Search

Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are common complications observed after adult spinal deformity (ASD) surgery and major cause for unplanned reoperations. In addition to spinal alignment, osteoporosis and paraspinal muscle (PSM) degeneration are reportedly indispensable factors that account for PJK/PJF. To investigate the utility of the preoperative risk assessment model using MRI-based skeletomuscular metrics in predicting PJK and/or PJF(PJK/PJF) after ASD correction. Retrospective case-control study. Consecutive series of 149 patients at a single academic institution. MRI-based measurements of vertebral bone quality at upper instrumented vertebra (VBQ-U) score and fat infiltration rate (FI%) of paraspinal muscle (PSM). We performed a retrospective analysis of patients with ASD who underwent ≥5-segment fusion. The vertebral bone quality (VBQ) scoring system was used to assess the bone quality. The PSM quality including FI% and cross-sectional area (CSA) was evaluated. Multivariate logistic regression was performed to determine potential risk factors of PJK/PJF. Of 149 patients who underwent ASD surgery, PJK/PJF was found in 45(30.2%). Mean VBQ-U scores were 3.45±0.64 and 3.00±0.56 for patients with and without PJK/PJF (p<.001). Mean FI% of PSM (L3/L4) was 27.9±12.8 and 20.7±13.3 for patients with and without PJK/PJF (p<.001). On multivariate analysis, the VBQ-U score and FI% of PSM were significant independent predictors of PJK/PJF. The AUC for the novel risk assessment model is 0.806, with a predictive accuracy of 86.7%. In patients undergoing ASD correction, paraspinal muscle and vertebral bone quality significantly outweigh radiographic alignment parameters in predicting PJK/PJF. The MRI-based risk assessment model offers a valuable tool for early assessing individualized risk for PJK/PJF. [ABSTRACT FROM AUTHOR]

Pedicle subtraction osteotomy (PSO) is effective for correcting spinal malalignment but is associated with high complication rates. The biomechanical effect of different PSO levels remains unclear, and no finite element (FE) analysis has compared L2-, L3-, L4-, and L5-PSOs. To assess the effects of PSO level on the spine's global range of motion, stresses on posterior instrumentation, load sharing with the anterior column, and proximal junctional stresses. A computational biomechanical analysis. A validated 3D spinopelvic FE model (T10-Pelvis) was used to perform PSOs at L2, L3, L4 and L5. Each model was instrumented with a 4-rod configuration (primary rods + in-line satellite rods) from T11-Pelvis. Simulation included a 2-step analysis; (1) applying 300 N to thoracic, 400 N to lumbar, and 400 N to sacrum, and (2) applying a 7.5 Nm moment to the top endplate of the T10 vertebral body. Acetabulum surfaces were fixed in all degrees of freedom. The range of motion, spinopelvic parameters (lumbar lordosis [LL], sacral slope [SS], pelvic incidence [PI], and pelvic tilt [PT]), PSO force, and von Mises stresses were measured. All models were compared with the L3-PSO model and percentage differences were captured. Compared to the intact alignment: LL increased by 48%, 45%, 59%, and 56% in the L2-, L3-, L4-, and L5-PSO models; SS increased by 25%, 15%, and 11% while PT decreased by 76%, 53%, and 45% in L2-, L3-, and L4-PSOs (SS and PT approximated intact model in L5-PSO); Lumbar osteotomy did not affect the PI. Compared to L3-PSO: L2-, L4-, and L5-PSOs showed up to 32%, 34%, and 34% lower global ROM. The least T10-T11 ROM was observed in L5-PSO. The left and right SIJ ROM were approximately similar in each model. Amongst all, the L5-PSO model showed the least ROM at the SIJ. Compared to L3-PSO, the L2-, L4-, and L5-PSO models showed up to 67%, 61%, and 78% reduced stresses at the UIV, respectively. Minimum stress at UIV+ was observed in the L3-PSO model. The L2-and L3-PSOs showed the maximum PSO force. The L5-PSO model showed the lowest stresses on the primary rods in all motions. Our FE investigation indicates that L5-PSO results in the greatest lumbar lordosis and lowest global, SIJ, and T10-T11 ROMs and stresses on the primary rods, suggesting potential mechanical benefits in reducing the risk of rod breakage. However, L4- and L5-PSOs led to the least force across the osteotomy site, which may increase the risk of pseudarthrosis. These findings provide biomechanical insights that may inform surgical planning, though further clinical investigation is essential to determine the optimal PSO level and validate these results. Understanding the biomechanical impact of PSO level is crucial for optimizing surgical outcomes and minimizing the risks of postoperative complications. [ABSTRACT FROM AUTHOR]

To compare the prognostic power of Hounsfield units (HU) and Vertebral Bone Quality (VBQ) score for predicting proximal junctional kyphosis (PJK) following long-segment thoracolumbar fusion to the upper thoracic spine (T1-T6). Vertebral bone quality around the upper instrumented vertebrae (UIV) was measured using HU on preoperative CT and VBQ on preoperative MRI. Spinopelvic parameters were also categorized according to the Scoliosis Research Society–Schwab classification. Univariable analysis to identify predictors of the occurrence of PJK and survival analyses with Kaplan-Meier method and Cox regression were performed to identify predictors of time to PJK (defined as ≥10° change in Cobb angle of UIV+2 and UIV). Sensitivity analyses showed thresholds of HU < 164 and VBQ > 2.7 to be most predictive for PJK. Seventy-six patients (mean age 66.0 ± 7.0 years; 27.6% male) were identified, of whom 15 suffered PJK. Significant predictors of PJK were high postoperative pelvic tilt (P = 0.038), high postoperative T1-pelvic angle (P = 0.041), and high postoperative PI-LL mismatch (P = 0.028). On survival analyses, bone quality, as assessed by the average HU of the UIV and UIV+1 was the only significant predictor of time to PJK (odds ratio [OR] 3.053; 95% CI 1.032–9.032; P = 0.044). VBQ measured using the UIV, UIV+1, UIV+2, and UIV–1 vertebrae approached, but did not reach significance (OR 2.913; 95% CI 0.797–10.646; P = 0.106). In larger cohorts, VBQ may prove to be a significant predictor of PJK following long-segment thoracolumbar fusion. However, Hounsfield units on CT have greater predictive power, suggesting preoperative workup for long-segment thoracolumbar fusion benefits from computed tomography versus magnetic resonance imaging alone to identify those at increased risk of PJK. [ABSTRACT FROM AUTHOR]

We sought to evaluate the clinical impact of lordosis orientation (LO) on proximal junctional kyphosis (PJK) development in adult spinal deformity surgery. This study included 152 patients who underwent low thoracic (T9–T12) to pelvis fusion and were followed up for ≥2 years. In the literature, 6 radiographic parameters representing LO were introduced, such as uppermost instrumented vertebra (UIV) slope, UIV inclination, UIV−femoral angle (UIVFA), thoracolumbar tilt, thoracolumbar slope, and lordosis tilt. Various clinical and radiographic factors including 6 LO parameters were investigated using logistic regression analysis to identify risk factors for PJK. The mean age was 69.4 years, and 136 patients were females (89.5%). PJK developed in 65 patients (42.8%). Multivariate logistic regression analysis revealed that only small postoperative pelvic incidence (PI)–lumbar lordosis (LL) (odds ratio [OR] = 0.962, 95% confidence interval: 0.929–0.996, P = 0.030) and large UIVFA (OR = 1.089, 95% confidence interval: 1.028–1.154, P = 0.004) were significant for PJK development. UIVFA showed significantly positive correlation with pelvic tilt (CC = 0.509), thoracic kyphosis (CC = 0.384), and lordosis distribution index (CC = 0.223). UIVFA was also negatively correlated with sagittal vertical axis (CC = −0.371). However, UIVFA did not correlate with LL, PI-LL, or T1 pelvic angle. LO significantly increases the risk of PJK development in ASD surgery. Multivariate analysis revealed that smaller postoperative PI-LL and greater UIVFA were significant risk factors for PJK. Surgeons should avoid undercorrection and overcorrection to prevent PJK development. [ABSTRACT FROM AUTHOR]

Proximal junctional failure following surgical correction for adult spinal deformity significantly impacts quality of life and increases the economic burden of treating underlying spinal deformity. The objective of this cadaver study was to determine optimal tension parameters in junctional tethers for proximal junctional kyphosis prevention. Cadaveric specimens were used to establish the optimal tension range in polyethylene tethering devices, such as the VersaTie (NuVasive) used in this study. Three specimens were instrumented to test tether tensions of 0, 75, and 150 Newtons (N) at L1-L2, T9-T10, and T3-T4. An optical tracking system was used to measure when specimens reached proximal junctional kyphosis, experienced instrumentation or tissue failure, or reached a cap of 2500 cycles. Radiographs were obtained before and after testing. At all levels, use of a tether at tension forces of 75 N and 150 N elicited a protective effect. The only level in which a higher tension on the tether resulted in more protection was at T3-T4. When averaged, the use of a tether at tension forces of 75 N and 150 N showed 1000 cycles of protection at L1-L2, 2000 cycles at T9-T10, and 1426 cycles at T3-T4. Radiographic analysis corroborated these findings. The use of a tether in a cadaveric model prevents the development of proximal junctional kyphosis across all tested levels and an increased tension force of 150 N is protective at the proximal thoracic spine. These data can be used to develop further models for a tether system that reproducibly applies a fixed tension force above the thoracolumbar rod construct. [ABSTRACT FROM AUTHOR]

In patients undergoing adult spinal deformity (ASD) surgery, we sought to: (1) determine the relationship between dual-energy x-ray absorptiometry (DEXA)-measured bone mineral density (BMD), T-scores, and Hounsfield units (HU), and (2) compare the ability of DEXA-measured BMD, T-scores, and HU to predict mechanical complications and reoperations. A single-institution retrospective cohort study was undertaken for cases from 2013 to 2017. Inclusion criteria: ≥5-level-fusion, sagittal/coronal deformity, and 2-year follow-up. Multivariable regression controlled for age, body mass index, receiving anabolic medications, and postoperative sagittal vertical axis and pelvic-incidence lumbar-lordosis mismatch. A subanalysis was performed for osteopenic patients (–1 < T-score < –2). Of 145 patients undergoing ASD surgery, 72 (49.6%) had both preoperative DEXA and computed tomography scans. Mean DEXA-measured BMD was 0.91 ± 0.52 g/cm2, mean T-score was –1.61 ± 1.03, and mean HU was 153.5 ± 52.8. While no correlation was found between DEXA-measured BMD and HU (r = 0.17, P = 0.144), T-score and HU had a weakly positive correlation (r = 0.31, P = 0.007). Mechanical complications occurred in 48 (66.7%) patients, including 27 (37.5%) proximal junctional kyphosis (PJK), 1 (1.4%) distal junctional kyphosis, 5 (6.9%) implant failure, 30 (41.7%) rod fracture/pseudarthrosis, 42 (58.3%) reoperations, and 16 (22.2%) reoperations due to PJK. No association was found between DEXA-measured BMD or T-scores with mechanical complications or reoperations. While univariate regression showed a significant association between lower HU and PJK (OR 0.98, 95%CI 0.97–0.99, P = 0.011), the significance was lost after multivariable analysis. When considering osteopenic patients (n = 37), only DEXA-measured BMD was an independent risk factor for PJK (OR 0.01, 95%CI 0.00–0.09, P = 0.017), with a threshold of 0.82 g/cm2 (AUC 0.70, 95%CI 0.53–0.84, P = 0.019). Poor correlation was found between the 3 BMD modalities. DEXA-measured BMD may be superior to T-scores and HU in predicting PJK among patients with osteopenia with a threshold of BMD <0.82 g/cm2. [ABSTRACT FROM AUTHOR]

• Proximal junctional kyphosis after adult spinal deformity is multifactorial. • Osteopenia and sarcopenia are patient risk factors. • Possible risk factors other than osteopenia and sarcopenia were eliminated. • Sarcopenia was found to be a more important factor than osteopenia. Proximal junctional kyphosis (PJK) is a major mechanical complication after adult spinal deformity (ASD) surgery, and is multifactorial. Osteopenia and sarcopenia are patient risk factors, but it has not yet been well-documented which of them is the more significant risk factor. We retrospectively studied patients older than 50 years who underwent ASD surgery from the lower thoracic spine to the pelvis. In addition to patient demographic data and pre- and post-operative radiographic sagittal parameters (PI: pelvic incidence; LL: lumbar lordosis; SVA: sagittal vertical axis; PT: pelvic tilt), Hounsfield unit (HU) values on preoperative computed tomography and cross sectional area (CSA) and fatty infiltration ratio (FI%) of the paraspinal musculature (PSM) on preoperative magnetic resonance image were measured from the upper-instrumented vertebra (UIV) to UIV + 2 and averaged. PJK was observed in 11 of 29 patients. There was no statistical difference between the patients with and without PJK in age at surgery, sex, body mass index, bone mineral density, preoperative PI-LL, SVA, PT, postoperative PI-LL, SVA, PT, HU, and CSA. FI% in patients with PJK (25.0) was significantly higher than that (15.3) in patients without PJK (P = 0.001). Logistic regression analysis identified FI% of PSM as a significant independent factor of PJK (odds ratio, 1.973; 95% confidence interval, 1.290–5.554; P < 0.0001). After successful elimination of possible factors related to PJK other than sarcopenia and osteopenia, sarcopenia assessed by fatty degeneration of the PSM at the UIV was shown to be a more important factor than osteopenia for PJK after long fusion for ASD. [ABSTRACT FROM AUTHOR]

• Multiple-rod constructs associated with reduction in rod fracture, pseudoarthrosis, and re-operation when compared with 2-rod constructs. • Country of primary study was found to be significant modulator of heterogeneity for rod fracture. • Similar rates observed of proximal junctional kyphosis between multiple- and 2-rod constructs. Surgical approaches in adult spinal deformity are associated with high rates of adverse events including hardware failure and rod fracture. Recently, some reports have emerged comparing multiple-rod constructs with 2-rod constructs suggesting potential benefits with the former. However, these have been limited by variability in observed outcomes, which have limited the change of paradigm in adult spinal deformity surgery. To compare the rate of rod fracture, pseudoarthrosis, proximal junctional kyphosis and re-operation between 2-RC and M-RC. MEDLINE/Pubmed, Web of Science and Embase were searched without language restrictions for relevant articles from inception until October 2021. All observational cohort studies assessing patients with ADS undergoing 3-column osteotomy and comparing 2-RC with M-RC procedures on pseudarthrosis, rod fracture, kyphosis or reoperation were included. Data were independently extracted by 2 authors. Random-effects and Bayesian meta -analysis were used. Six primary studies met inclusion criteria, yielding a total of 448 participants, with 223 receiving 2-RC and 225 M-RC. The random-effects meta -analysis pointed to a significantly lower risk of rod fracture associated with M-RC (RR = 0.43, 95 %CI = 0.28–0.66), with moderate heterogeneity being observed (I2 = 20 %, p = 0.28). The random-effects meta -analysis pointed to a lower risk of pseudoarthrosis with M-RC than with 2-RC (RR = 0.49, CI = 0.28–0.84, to a lower rate of re-operation with M-RC than with 2-RC (RR = 0.52, CI = 0.28–0.97) and to a similar rate of proximal junctional kyphosis between 2-RC and M-RC patients (RR = 0.91, CI = 0.60–1.39). Low heterogeneity was observed for studies comparing pseudoarthrosis (I2 = 9 %, p = 0.35), re-operation (I2 = 0 %, p = 0.41) and proximal junctional kyphosis (I2 = 0 %, p = 0.85). These findings suggest that multiple rod-fracture constructs are associated with lower rates of rod fracture, re-operation rates, pseudoarthrosis but not proximal junctional kyphosis. Future studies should address the impact of other modulators of heterogeneity such as body mass index, metal alloys and length of the constructs. [ABSTRACT FROM AUTHOR]

Background Context: Prophylactic vertebroplasty (VP) is performed at the upper level of instrumentation during spinal fusion to reduce the risk of proximal junctional kyphosis (PJK), proximal junctional fracture (PJFx), and proximal junctional failure (PJF). This study investigated the effect of VP on patient outcomes after spinal fusion.Purpose: The aim of this systematic review was to evaluate the effect of prophylactic VP on the incidence of PJK in patients with spinal fusion.Study Design/setting: Level III, systematic review without meta-analysis.Patient Sample: Adult patients undergoing spinal fusion with VP.Methods: A PRISMA-compliant systematic literature review was conducted using PubMed/MEDLINE, Cochrane, and Embase. Included studies were published in English between January 1, 2001, and May 27, 2021, and reported primary data on adult patients undergoing spinal fusion with VP. Studies were excluded for insufficient surgical details; treatment for vertebral compression fracture; and case series and/or reports with <5 patients. The Newcastle-Ottawa Scale was used to assess risk of bias. The primary outcome of interest was PJK. Other outcomes included PJFx, PJF, and adverse events (eg, cement extravasation). Data were expressed as descriptive statistics.Results: Eight studies with 685 total patients (VP: 293 [42.8%]; No VP: 392 (57.2%)) were included. Five studies were comparative and three were single-arm. PJK incidence was reported in five studies (three comparatives, two single-arm) and ranged from 7.9% to 46.4%; incidence was lower in patients with VP in two of three (66.7%) comparative studies, and equal in one of three (33.3%). PJFx was reported in five studies (four comparatives, one single-arm) and ranged from 0.0% to 39.3%; incidence was lower in the VP group in two of four (50.0%) comparative studies, equal in one of four (25.0%), and higher in one of four (25.0%). PJF was reported in five studies (three comparatives, two single-arm) and ranged from 0.0% to 39.3%; incidence was lower in the VP group in two of three (66.7%) comparative studies and equal in one of three (33.3%). Cement extravasation was reported by four studies and ranged from 0% (0/36) to 48.3% (57/118) in patients with prophylactic VP.Conclusions: Evidence on whether prophylactic VP decreases the incidence of PJK, PJFx, and PJF after spinal fusion is inconclusive and conflicting. Additionally, the risk of cement extravasation following prophylactic VP could not be evaluated due to insufficient evidence. Further research is needed to determine whether VP has a significant impact on patient outcomes and risks. [ABSTRACT FROM AUTHOR]

Adjacent level degeneration is a precursor to construct failure in adult spinal deformity surgery, but whether construct design affects adjacent level degeneration risk remains unclear. Here we present a biomechanical profile of common deformity correction constructs and assess adjacent level biomechanics. Standard nondestructive flexibility tests (7.5 Nm) were performed on 21 cadaveric specimens: 14 pedicle subtraction osteotomies (PSOs) and 7 anterior column realignment (ACR) constructs. The ranges of motion (ROM) at the adjacent free level in flexion, extension, axial rotation, and lateral bending were measured and analyzed. ACR constructs had a lower ROM change on flexion at the proximal adjacent free level than constructs with PSO (1.02 vs. 1.32, normalized to the intact specimen, P < 0.01). Lateral lumbar interbody fusion adjacent to PSO and 4 rods limits ROM at the free level more effectively than transforaminal interbody fusion and 2 rods in correction constructs with PSO. Use of 2 screws to anchor the ACR interbody further decreased ROM at the proximal adjacent free level on flexion, but adding 4 rods in this setting added no further limitation to adjacent segment motion. ACR constructs have less ROM change at the adjacent level compared to PSO constructs. Among constructs with ACR, anchoring the ACR interbody with 2 screws reduces motion at the proximal adjacent free level. When PSOs are used, lateral lumbar interbody fusion adjacent to the PSO level has a greater reduction in adjacent-segment motion than transforaminal interbody fusion, suggesting that deformity construct configuration influences proximal adjacent-segment biomechanics. [ABSTRACT FROM AUTHOR]

We sought to investigate the risk factors of suboptimal postoperative outcomes after short-segment surgery for degenerative lumbar spinal stenosis and severe sagittal imbalance and to recommend the appropriate candidates for the short fusion. A total of 101 elderly subjects who underwent short-segment surgery were included. Preoperative sagittal vertical axis decreased to ≤50 mm was determined as sagittal compensation; otherwise, it was determined as sagittal decompensation. At the latest follow-up, 64 patients with sagittal decompensation and 14 patients with proximal junctional kyphosis (PJK) were detected. Sagittal imbalance with the related symptoms was named as symptomatic sagittal imbalance. Preoperative clinical data and spinopelvic parameters were collected and compared between different groups. Symptomatic sagittal imbalance and severe degeneration of paravertebral muscle were revealed to be the risk factors for sagittal decompensation and PJK. More sagittal decompensations (100%) and PJKs (60%) were observed in patients with both of these risk factors. On the contrary, postoperative outcomes were superior with less sagittal decompensation (46.9%) and PJK (0%) in those with neither of the 2 factors. Symptomatic sagittal imbalance and severe degeneration of paraspinal muscle are the risk factors predisposing suboptimal surgical outcomes after lumbar short-segment decompression and fusion for degenerative lumbar spinal stenosis. We believe essential spinal function and substantial quality of paraspinal muscle are the keys to long-lasting good outcomes. [ABSTRACT FROM AUTHOR]

To review outcomes of patients undergoing spinal fusion with prophylactic cement augmentation (CA) of pedicle screws and adjacent levels. In a retrospective case-control study, 59 patients underwent CA of pedicle screws for spinal fusion between 2003 and 2018. Most patients (83%) underwent postoperative CA, while 17% underwent intraoperative CA. Outcomes of CA techniques were compared, and patients undergoing CA for a thoracolumbar fusion (n = 51) were compared with a cohort not undergoing CA (n = 39). Mean follow-up was 3 years. In patients receiving CA, survivorship free of proximal junctional kyphosis (PJK) was 94%, 60%, and 20% at 2, 5, and 10 years postoperatively. Survivorship free of revision was 95%, 83%, and 83% at 2, 5, and 10 years postoperatively. Development of PJK (P = 0.02, odds ratio [OR] 24.44) was associated with revision surgery. There were 4 (7%) cardiopulmonary complications. Patients who received CA for thoracolumbar fusion were older (70 years vs. 65 years) and were more likely to have osteoporosis (53% vs. 5%) than patients who did not receive CA. CA was associated with a decreased risk of PJK (P = 0.009, OR 0.16), while osteoporosis (P = 0.05, OR 4.10) and fusion length ≥8 levels (P = 0.06, OR 2.65) were associated with PJK. PJK was associated with revision surgery (P = 0.006, OR 12.65). CA allows for substantial rates of radiographic PJK; however, this typically does not result in a need for revision surgery and leads to revision and PJK rates that are comparable to patients undergoing long segment fusions without osteoporosis. [ABSTRACT FROM AUTHOR]

Background Context: The effect of the degree of lumbar lordosis (LL) correction on proximal junctional kyphosis (PJK) has not been analyzed in context of the age-adjusted sagittal alignment goal.Purpose: To determine the effect of sagittal correction on the incidence of PJK after an age-adjusted analysis in patients with adult spinal deformity (ASD).Study Design/setting: Retrospective comparative study.Patient Sample: Seventy-eight ASD patients who underwent deformity correction.Outcome Measures: Visual analog scale (VAS), Oswestry Disability Index (ODI), and imaging.Methods: This study included 78 ASD patients who underwent deformity correction and were followed-up more than 2 years. Patients were grouped according to the degree of LL correction relative to pelvic incidence (PI) by adjusting for age using the following formula: (age-adjusted ideal PI - LL) - (postoperative PI - LL). These were group U (undercorrection; <-10˚, N=15), group I (ideal correction; -10˚-10˚, N=34), and group O (over correction, >10˚, N=29). Various clinical and radiological parameters were compared among groups. The risk factors for PJK were also evaluated.Results: The overall incidence of PJK was 32.1% (25/78), with significantly higher PJK rate in group O (48.3%) compared with groups U (13.3%) and I (26.5%) (p=.041). The degree of postoperative LL correction relative to the PI by adjusting for age was a risk factor for the development of PJK (11.4° for PJK vs. 0.2° for non-PJK, p=.033). In addition, 2-year postoperative VAS (7.0 vs. 3.4, p<.001) and ODI (28.9 vs. 24.8, p=.040) scores were significantly higher in the PJK group than in the non-PJK group. A small PI (PI < 45°) was associated with a tendency of overcorrection (73.3%, P < 0.001) and thereby with the high incidence of PJK (53.3%, p=.005).Conclusions: Overcorrection of LL relative to PI considering age-adjusted ideal sagittal alignment tends to increase the incidence of PJK. The incidence of PJK is expected to be high in patients with low PI (<45°) because of the tendency of overcorrection. To reduce the risk of PJK, surgeons should take age-adjusted parameters into account and exercise caution not to overcorrect patients with low PI, since this can result in suboptimal clinical outcomes. [ABSTRACT FROM AUTHOR]

Proximal junctional kyphosis (PJK) and proximal junction failure are common and costly complications after long-segment adult spinal deformity (ASD) correction. Although much research has focused on the concept of "softening the landing" to prevent proximal junction pathologies, long-segment constructs largely deviate from the force-deformation curve of the physiologic spine. Our novel distributed loading technique for ASD correction is described using multimaterial, long-segment constructs to create a biomechanically sound, yet physiologic, decremental stiffness toward the rostral end. Operative steps detail the custom-designed constructs of dual-headed pedicle screws and varied rod diameters and materials (cobalt chromium or titanium) for an initial 20 patients (mean 66.6 ± 4.8 years). Standing scoliosis films were obtained preoperatively and at regular intervals postoperatively to assess for PJK. No patient had evidence of PJK or proximal junction failure at latest radiographic follow-up (mean 17.9 months, range 13−25 months). Radiographic findings for sagittal vertical axis averaged 11.2 ± 5.6 cm preoperatively and 3.6 ± 2.3 cm postoperatively. Compared with preoperative parameters, postoperative reductions in pelvic incidence-lumbar lordosis mismatch averaged 28.7 ± 12.9 degrees, and sagittal vertical axis averaged 7.6 ± 5.2 cm while PJA was essentially unchanged. Preliminary results suggest that the distributed loading technique is promising for prevention of PJK with stiffness gradients that mimic the force-deformation curve of the physiologic posterior tension band. Our technique may optimize the degree of stress at the proximal junction without overwhelming the anterior column bony while remodeling and mature arthrodesis takes place. [ABSTRACT FROM AUTHOR]

Background Context: It is unknown whether upper instrumented vertebra (UIV) pedicle screw trajectory and UIV screw-rod angle are associated with development of proximal junctional kyphosis (PJK) and/or proximal junctional failure (PJF).Purpose: To determine whether (1) the cranial-caudal trajectory of UIV pedicle screws and (2) UIV screw-vertebra angle are associated with PJK and/or PJF after long posterior spinal fusion in patients with adult spinal deformity (ASD).Study Design/setting: Retrospective review.Patient Sample: We included 96 patients with ASD who underwent fusion from T9-T12 to the pelvis (>5 vertebrae fused) between 2008 and 2015.Outcome Measures: Pedicle screw trajectory was measured as the UIV pedicle screw-vertebra angle (UIV-PVA), which is the mean of the two angles between the UIV superior endplate and both UIV pedicle screws. (Positive values indicate screws angled cranially; negative values indicate screws angled caudally.) We measured UIV rod-vertebra angle (UIV-RVA) between the rod at the point of screw attachment and the UIV superior endplate.Methods: During ≥2-year follow-up, 38 patients developed PJK, and 28 developed PJF. Mean (± standard deviation) UIV-PVA was -0.9° ± 6.0°. Mean UIV-RVA was 87° ± 5.2°. We examined the development of PJK and PJF using a UIV-PVA/UIV-RVA cutoff of 3° identified by a receiver operating characteristic curve, while controlling for osteoporosis, age, sex, and preoperative thoracic kyphosis.Results: Patients with UIV-PVA ≥3° had significantly greater odds of developing PJK (odds ratio 2.7; 95% confidence interval: 1.0-7.1) and PJF (odds ratio 3.6; 95% confidence interval: 1.3-10) compared with patients with UIV-PVA <3°. UIV-RVA was not significantly associated with development of PJK or PJF.Conclusions: In long thoracic fusion to the pelvis for ASD, UIV-PVA ≥3° was associated with 2.7-fold greater odds of PJK and 3.6-fold greater odds of PJF compared with UIV-PVA <3°. UIV-RVA was not associated with PJK or PJF.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

• Proximal junctional kyphosis has two widely known classification systems. • Current classifications measure the mechanism of failure and severity with treatment indication. • Future classification systems should incorporate etiology, mechanism of failure, and severity. Proximal junctional kyphosis is a kyphotic deformity following spine instrumentation, predominantly seen in scoliosis patients. There have been previous attempts to develop classification schema of PJK. We analyzed the factors contributing to PJK based upon our own clinical experience with the goal of developing a clinical guidance tool which took into account both etiology and mechanism of failure. Methods : We performed a retrospective analysis of all re-operation thoracolumbar surgeries at a single institution over a 14-year period. Patients with PJK were identified and categorized based upon the etiology, mechanism of failure, and an indication of revision. Next, we conducted a systematic review on articles emphasizing a classification system for PJK. Results : Fourteen PJK patients were identified out of 121 patients who required revision spine surgery. The average age was 64.9 ± 10.2 years, with 10 males (71%) and 4 females (29%). Three primary etiologies were identified: 6/14 (47%) overcorrection, 6/14 (47%) osteopenia, and 2/14 (14%) ligamentous disruption. The mechanism of failure was likewise divided into three categories: 9/14 (64%) compression fracture, 1/14 (7%) hardware failure, and 4/14 (29%) disc degeneration. The relationship between osteopenia and the development of a compression fracture leading to PJK was statistically significant (p = 0.031). Conclusion : There are multiple current classification systems for PJK. Our study findings were in line with previously published literature and suggest the need for a future classification system combining both etiology, mechanism of failure, and severity of disease. [ABSTRACT FROM AUTHOR]

Background Context: Correction of adult spinal deformity (ASD) by long segment instrumented spinal fusion is an increasingly common surgical intervention. However, it is associated with high rates of complications and revision surgery, especially in the elderly patient population. The high construct stiffness of instrumented thoracolumbar spinal fusion has been postulated to lead to a higher incidence of proximal junctional kyphosis (PJK) and failure (PJF). Several cadaveric biomechanical studies have reported on surgical techniques to reduce the incidence of PJF/PJK. As yet, no overview has been made of these biomechanical studies.Purpose: To summarize the evidence of all biomechanical studies that have assessed techniques to reduce PJK/PJF following long segment instrumented spinal fusion in the ASD patient population.Study Design: A systematic review.Methods: EMBASE and MEDLINE databases were searched for human and animal cadaveric biomechanical studies investigating the effect of various surgical techniques to reduce PJK/PJF following long segment instrumented thoracolumbar spinal fusion in the adult patient population. Studied techniques, biomechanical test methods, range of motion (ROM), intervertebral disc pressure (IDP) and other relevant outcome parameters were documented.Results: Twelve studies met the inclusion criteria. Four of these studies included non-human cadaveric material. One study investigated the prophylactic application of cement augmentation (vertebroplasty), whereas the remaining studies investigated semi-rigid junctional fixation techniques to achieve a gradual transition zone of forces at the proximal end of a fusion construct, so-called topping-off. An increased gradual transition zone in terms of ROM compared to pedicle screw constructs was demonstrated for sublaminar tethers, sublaminar tape, pretensioned suture loops, transverse hooks and laminar hooks. Furthermore, reduced IDP was found after the application of sublaminar tethers, suture loops, sublaminar tapes and laminar hooks. Finally, two-level prophylactic vertebroplasty resulted in a lower incidence of vertebral compression fractures in a flexion-compression experiment.Conclusions: A variety of techniques, involving either posterior semi-rigid junctional fixation or the reinforcement of vertebral bodies, has been biomechanically assessed. However, the low number of studies and variation in study protocols hampers direct comparison of different techniques. Furthermore, determination of what constitutes an optimal gradual transition zone and its translation to clinical practice, would aid comparison and further development of different semi-rigid junctional fixation techniques. Even though biomechanics are extremely important in the development of PJK/PJF, patient-specific factors should always be taken into account on a case-by-case basis when considering to apply a semi-rigid junctional fixation technique. [ABSTRACT FROM AUTHOR]

Spinopelvic parameters have hitherto dictated much of adult spinal deformity (ASD) correction. The Roussouly classification is used for the normal adult spine. We evaluated whether a correlation would be found between the Roussouly type and the rate of revision surgery in patients with ASD undergoing circumferential minimally invasive spinal (cMIS) correction. A multicenter retrospective review of patients who had undergone cMIS surgery for ASD was performed. The inclusion criteria were age ≥18 years and 1 of the following: coronal Cobb angle >20°, sagittal vertical axis >5 cm, pelvic tilt >20°, pelvic incidence (PI) to lumbar lordosis (LL) mismatch >10°, cMIS surgery, and a minimum of 2 years of follow-up data available. The patients were classified by Roussouly type, and the clinical and radiographic outcomes were evaluated. A total of 104 patients were included in the present analysis. Of the 104 patients, 41 had Roussouly type 1, 32 had type 2, 23 had type 3, and 8 had type 4. Preoperatively, the patients with type 4 had the highest PI (P = 0.002) and LL (P < 0.001). Postoperatively, the PI-LL mismatch, Cobb angle, and sagittal vertical axis were not different among the 4 groups. However, the patients with type 2 had had the highest rate of complications (type 1, 29.3%; type 2, 61.3%; type 3, 34.8%; type 4, 25.0%; P = 0.031). The reoperation rates were comparable (type 1, 19.5%; type 2, 38.7%; type 3, 13.0%; type 4, 12.5%; P = 0.097). The reoperation rates for adjacent segment degeneration or proximal junctional kyphosis were also comparable (P = 0.204 and P = 0.060, respectively). We did not find a clear correlation between Roussouly type and the rate of revision surgery for adjacent segment disease or proximal junctional kyphosis in patients who had undergone cMIS surgery for ASD. [ABSTRACT FROM AUTHOR]

Proximal junctional kyphosis (PJK) is a common sagittal complication of adolescent idiopathic scoliosis (AIS) after corrective surgery, leading to new deformities, pain, and, even, revision surgery. In the present study, we investigated the risk and predictive factors for PJK in patients who had undergone Lenke type 5 AIS correction to identify the parameters relevant to intraoperative guidance. A total of 35 patients with Lenke type 5 AIS who had undergone corrective surgery at our hospital from January 2008 to February 2016 were divided into the PJK (n = 15) and non-PJK (n = 20) groups. Correlation and receiver operating characteristic curve analyses were performed to screen the parameters for significance and calculate the thresholds. A survival analysis was performed to examine the differences between the 2 groups. Independent t tests revealed significant differences between the 2 groups in the preoperative pelvic incidence, preoperative pelvic tilt, postoperative proximal junctional angle (PJA), and postoperative thoracic kyphosis (TK). The postoperative PJA, postoperative TK, and other parameters correlated significantly with changes in the PJA at the final follow-up. The receiver operating characteristic curves revealed that the postoperative PJA and postoperative TK effectively predicted for the occurrence of PJK, with a threshold of 9.45° and 25.25°, respectively. The estimated survival times were 14.7 months for a PJA >9.45° and TK >25.25°, 19.2 months for a PJA >9.45°, and 33.9 months for TK >25.25°. The results of the present study have shown that the postoperative PJA and postoperative TK can be used to effectively predict for the occurrence of PJK in patients with Lenke type 5 AIS after corrective surgery, with a threshold of 9.45° and 25.25°, respectively. [ABSTRACT FROM AUTHOR]

Background Context: Proximal junctional failure (PFJ) is a common and dreaded complication of adult spinal deformity. Previous research has identified parameters associated with the development of PJF and the search for radiographic and clinical variables continues in an effort to decrease the incidence of PFJ. The lordosis distribution index (LDI) is a parameter not based on pelvic incidence. Ideal values for LDI have been established in prior literature with demonstrated association with PJF.Purpose: The purpose of this study is compare PJF and mechanical failure rates between patients with ideal and nonideal LDI cohort.Study Design: This is a retrospective, single-center case-controlled study.Patient Sample: Adult patients who underwent surgical treatment for spinal deformity as defined by the SRS-Schwab criteria between 2001 and 2016 were included. Furthermore, fusion constructs spanned at least four vertebral segments with the upper instrumented vertebra (UIV) T9 or caudal. Patients who were under the age of 18, those with radiographic data less than 1 year, and those with neoplastic or trauma etiologies were excluded. Prior thoracolumbar spine surgery was not an exclusion criterion.Outcome Measures: The outcome measures were physiologic in nature: The primary outcome was defined as PFJ. The International Spine Study Group (ISSG) definition for PJF was used, which includes postoperative fracture of the UIV or UIV+1, instrumentation failure at UIV, PJA increase greater than 15° from preoperative baseline or extension of the construct needed within 6 months. Secondary outcomes included extension of the construct after 6 months or revision due to instrumentation failure, pseudarthrosis or distal junctional failure.Methods: A portion of this project was funded through National Institute of Health Grant 5UL1TR001067-05. The authors have no conflict of interest related to this study. The records of patients meeting the inclusion criteria were reviewed. Clinical and radiographic data were extracted and analyzed. Univariate cox proportional hazard models were used to identify factors associated with mechanical failure and included in a multivariate Cox proportional hazards model.Results: There were 187 patients that met the inclusion criteria. Univariate analysis demonstrated the number of levels fused, instrumentation to the sacrum or pelvis, PI-LL difference between pre- and postoperative states, T1-SPI, T9-SPI, and postoperative LDI (treated as a continuous variable). When LDI was treated as a categorical variable using an LDI cutoff of less than 0.5 for hypolordotic, 0.5 to 0.8 for aligned and greater than 0.8 for hyperlordotic, there was no difference in failure rates between the two groups.Conclusions: Lumbar lordosis is an important parameter in adult deformity. However, the LDI is an imperfect variable and previously developed categories did not show differences in failure rates in this cohort. [ABSTRACT FROM AUTHOR]

This case series examined patients undergoing caudal extension of prior fusion without alteration of the prior upper instrumented vertebra (UIV) to assess patient outcomes and rates of proximal junctional kyphosis (PJK)/proximal junctional failure (PJF). Patients eligible for 2-year minimum follow-up undergoing caudal extension of prior fusion with unchanged UIVs were identified. These patients were evaluated for PJK/PJF, and patient reported outcomes were recorded. In total, 40 patients were included. Mean follow-up duration was 2.2 ± 0.3 years. Patients in this cohort had poor preoperative sagittal alignment (pelvic incidence minus lumbar lordosis [PI-LL] 26.7°, T1 pelvic angle [TPA] 29.0°, sagittal vertical axis [SVA] 93.4 mm) and achieved substantial sagittal correction (ΔSVA −62.2 mm, ΔPI-LL −19.8°, ΔTPA −11.1°) after caudal extension surgery. At final follow-up, there was a 0% rate of PJF among patients undergoing caudal extension of previous fusion without creation of a new UIV, but 27.5% of patients experienced PJK. Patients experienced significant improvement in both the Oswestry Disability Index and Scoliosis Research Society-22r total score at 2 years postoperatively (P < 0.05). In total, 7.5% (n = 3) of patients underwent further revision, at an average of 1.1 ± 0.54 years after the surgery with unaltered UIV. All 3 of these patients underwent revision for rod fracture with no revisions for PJK/PJF. Patients undergoing caudal extension of previous fusions for sagittal alignment correction have high rates of clinical success, low revision surgery rates, and very low rates of PJF. Minimizing repetitive tissue trauma at the UIV may result in decreased PJF risk because the PJF rate in this cohort of patients with unaltered UIV is below historical PJF rates of patients undergoing sagittal balance correction. [ABSTRACT FROM AUTHOR]

• Menopausal metabolic changes may predispose to fusion related complications. • Postmenopausal patients have higher rates of pseudarthrosis and PJK. • The need for revision surgery is not higher in postmenopausal patients. Menopause leads to fluctuations in androgenic hormones which directly affect bone metabolism. Bone resorption, mineralization, and remodeling at fusion sites are essential in order to obtain a solid and biomechanically stable fusion mass. Bone metabolic imbalance seen in the postmenopausal state may predispose to fusion related complications. The aim of this study was to investigate fusion outcomes in lumbar spinal fusion surgery in women based on menopausal status. A retrospective analysis of all female patients who underwent posterior lumbar decompression and fusion at a single institution from 2013 to 2017 was performed. A total of 112 patients were identified and stratified into premenopausal (n = 25) and postmenopausal (n = 87) groups. Clinical and radiographic data was assessed at 1 year follow up. Postmenopausal patients had a higher rates of pseudarthrosis (11.63% vs 0%, p = 0.08), PJK (15.1% vs 4%, p = 0.14), and revision surgery (3.5% vs 0%, p = 0.35). The number of levels fused was associated with increased risk of pseudarthrosis (OR 1.4, p = 0.02); however, there was no association between age, hormonal use, prior tobacco use, or T-score. Age was associated with increased risk of developing PJK (OR = 1.11, p = 0.01); however, PJK was not associated with menopause, hormonal use, prior tobacco use, or T-score. Revision surgery was not associated with age, hormonal use, prior tobacco use, or T-score. This study suggests that postmenopausal women may be prone to have higher rates of pseudarthrosis, PJK and revision surgery, although our results were not statistically significant. Larger studies with longer follow up will help elucidate the true effects of menopause in spine surgery. [ABSTRACT FROM AUTHOR]

To assess the role of the difference between the proximal junctional angle (PJA) and rod contouring angle (RCA) (PJA-RCA) in the development of postoperative proximal junctional angle (PJK) in Lenke I and II adolescent idiopathic scoliosis (AIS) patients. We performed a retrospective analysis of 84 Lenke I and II AIS patients who underwent posterior segmental spinal instrumentation and fusion between 2012 and 2018 (minimum follow-up of 1.5 years and an average follow-up of 2 years) at a single institution. The full-spine x-ray films taken at the preoperative, postoperative, and final follow-ups were measured for each patient. The radiographic parameters were compared between the PJK and non-PJK groups, and binary logistic regression with forward elimination (conditional) was also performed to identify the risk factors for the occurrence of PJK. Among the 84 patients (mean age: 14.63 ± 1.33 years), the overall incidence of PJK was 23.81%. The PJK group showed a larger preoperative pelvic incidence (55.66° ± 8.66° vs. 50.29°±8.27°, P = 0.045), thoracic kyphosis (TK) (32.44° ± 5.60° vs. 27.19° ± 5.14°, P = 0.007) and sagittal vertical axis (SVA) (40.99 ± 21.82 mm vs. 18.13 ± 28.64 mm, P = 0.013) than the non-PJK group. Postoperatively, the PJK group showed a larger decrease in the TK (–10.62° ± 3.19° vs. –5.56° ± 1.17°, P < 0.001) and SVA (–24.28 ± 18.22 mm vs. –10.83 ± 15.02 mm, P = 0.007). In addition, the PJK group had significantly larger postoperative PJA (9.83° ± 2.64° vs. 5.77° ± 3.06°, P < 0.001) and postoperative PJA-RCA (6.56° ± 3.69° vs. 1.55° ±3.32°, P < 0.001). The proportion of patients with a PJA-RCA value greater than 5° was significantly larger in the PJK group (65.00% vs. 18.75%, P < 0.001). At the last follow-up, the PJK patients had significantly larger TK (35.11° ± 5.51° vs. 26.53° ± 4.71°, P < 0.001) and SVA (22.83 ±23.12 mm vs. 3.46 ±26.24 mm, P = 0.038). Binary logistic regression analysis showed that decreases in TK and postoperative PJA-RCA were the primary contributors to PJK in patients with AIS. Large postoperative PJA-RCA and decreased TK are risk factors for PJK in Lenke I and II AIS patients, especially those with PJA-RCA greater than 5°, and the occurrence of PJK should be highly considered. [ABSTRACT FROM AUTHOR]

Vertebral osteomyelitis manifesting as a compression fracture misdiagnosed in the setting of steroid-induced or senile osteoporosis is very rare, although such patients are prone to infection or reactivation, as their immune system is exhausted. Spondylodiscitis occurring at adjacent levels following instrumented spinal fusion leading to pathologic fracture and proximal junctional failure, especially caused by tuberculosis, to our knowledge, has not been discussed in the literature. In case 1, a 61-year-old woman with osteoporotic T12 collapse was treated with corpectomy, anterior reconstruction, and posterior fixation from T9-L2. Initial biopsy and culture were normal. She presented 4 months later with compression fracture of T8; T8 corpectomy with anterior reconstruction and proximal extension of the construct was performed. In case 2, a 65-year-old woman with multiple comorbidities and osteoporotic L1 compression fracture was treated with L1 corpectomy, anterior reconstruction, and posterior instrumentation from T11-L3. She presented 4 months later with T10 vertebral body acute collapse; 2-stage anterior corpectomy and reconstruction was performed. In both cases, probing the affected vertebral body yielded pus. Pus and bone tissue samples sent for culture and histopathologic examination were positive for tuberculosis suggesting tuberculous spondylitis in both cases. In both patients, tuberculous spondylodiscitis at the proximal adjacent level was diagnosed <1 year after the initial spinal surgery. Neither patient had a previous history of pulmonary or extrapulmonary tuberculosis. They were successfully treated with antituberculous therapy and proximal extension of the construct with anterior reconstruction. Adjacent segment spondylodiscitis should be suspected and intraoperative biopsy must be considered for histopathologic and microbiologic examination to rule out subclinical infection in immunosuppressed patients with multiple comorbidities. Management should be individualized, considering the context of infection, causative organism, extent of bone destruction, and neurologic involvement. [ABSTRACT FROM AUTHOR]

Proximal junctional failure (PJF) is a major and sometimes devastating problem following adult spinal deformity (ASD) correction surgery. Common consensus still lags on guidelines for preventing and managing these complications. Surgical treatment of scoliosis in the presence of osteogenesis imperfecta (OI) in the pediatric population is well described. The complication rates are unusually higher in this special subset of patients owing to poor quality of bone. There is a paucity of literature focusing on surgical techniques, strategies, and problems involved in the management of ASD associated with OI. We report a 59-year-old female with type 1 OI and adult scoliosis who underwent T10-to-pelvis fusion for ASD according to the principles of adult deformity correction. At a 1-year follow-up, she presented with asymptomatic proximal junctional kyphosis of 45° and 2 weeks later had PJF along with spinal cord injury after a fall. On computed tomography scan, kyphosis was increased to 60° at T9-T10. She underwent decompression and revision deformity correction using quadruple rods, with extension of instrumentation to T2 with soft landing using rib bands. At a 4-year follow-up, she had a good functional outcome after revision surgery. This is the first report of successful management of PJF following ASD correction in the presence of OI using this technique. Suboptimal hold of implants due to poor bone quality must be at the focus of any surgical planning for these patients. All possible strategies to prevent PJF must be considered when planning the deformity correction in adults with OI. [ABSTRACT FROM AUTHOR]

Background Context: The postoperative recovery patterns of cervical deformity patients, thoracolumbar deformity patients, and patients with combined cervical and thoracolumbar deformities, all relative to one another, is not well understood. Clear objective benchmarks are needed to quantitatively define a "good" versus a "bad" postoperative recovery across multiple follow-up visits, varying deformity types, and guide expectations.Purpose: To objectively define and compare the complete 2-year postoperative recovery process among operative cervical only, thoracolumbar only, and combined deformity patients using area-under-the-curve (AUC) methodology.Study Design/setting: Retrospective review of 2 prospective, multicenter adult cervical and spinal deformity databases.Patient Sample: One hundred seventy spinal deformity patients.Outcome Measures: Common health-related quality of life (HRQOL) assessments across both databases included the EuroQol 5-Dimension Questionnaire and Numeric Rating Scale (NRS) back pain assessment. In order to compare disability improvements, the Neck Disability Index (NDI) and the Oswestry Disability Index (ODI) were merged into one outcome variable, the ODI-NDI. Both assessments are gauged on the same scale, with minimal question deviation. Sagittal Radiographic Alignment was also assessed at pre- and all postoperative time points.Methods: Operative deformity patients >18 years old with baseline (BL) to 2-year HRQOLs were included. Patients were stratified by cervical only (C), thoracolumbar only (T), and combined deformities (CT). HRQOL and radiographic outcomes were compared within and between deformity groups. AUC normalization generated normalized HRQOL scores at BL and all follow-up intervals (6 weeks, 3 months, 1 year, and 2 year). Normalized scores were plotted against follow-up time interval. AUC was calculated for each follow-up interval, and total area was divided by cumulative follow-up length, determining overall, time-adjusted HRQOL recovery (Integrated Health State, IHS). Multiple linear regression models determined significant predictors of HRQOL discrepancies among deformity groups.Results: One hundred seventy patients were included (27 C, 27 T, and 116 CT). Age, BMI, sex, smoking status, osteoporosis, depression, and BL HRQOL scores were similar among groups (p >. 05). T and CT patients had higher comorbidity severities (CCI: C 0.696, T 1.815, CT 1.699, p = .020). Posterior surgical approaches were most common (62.9%) followed by combined (28.8%) and anterior (6.5%). Standard HRQOL analysis found no significant differences among groups until 1-year follow-up, where C patients exhibited comparatively greater NRS back pain (4.88 vs. 3.65 vs. 3.28, p = .028). NRS Back pain differences between groups subsided by 2-years (p>.05). Despite C patients exhibiting significantly faster ODI-NDI minimal clinically important difference (MCID) achievement (33.3% vs. 0% vs. 23.0%, p < .001), all deformity groups exhibited similar ODI-NDI MCID achievement by 2-years (51.9% vs. 59.3% vs. 62.9%, p = 0.563). After HRQOL normalization, similar results were observed relative to the standard analysis (1-year NRS Back: C 1.17 vs. T 0.50 vs. CT 0.51, p < .001; 2-year NRS Back: 1.20 vs. 0.51 vs. 0.69, p = .060). C patients exhibited a worse NRS back normalized IHS (C 1.18 vs. T 0.58 vs. CT 0.63, p = .004), indicating C patients were in a greater state of postoperative back pain for a longer amount of time. Linear regression models determined postoperative distal junctional kyphosis (adjusted beta: 0.207, p = .039) and osteoporosis (adjusted beta: 0.269, p = .007) as the strongest predictors of a poor NRS back IHS (model summary: R2 = 0.177, p = .039).Conclusions: Despite C patients exhibiting a quicker rate of MCID disability (ODI-NDI) improvement, they exhibited a poorer overall recovery of back pain with worse NRS back scores compared with BL status and other deformity groups. Postoperative distal junctional kyphosis and osteoporosis were identified as primary drivers of a poor postoperative NRS back IHS. Utilization of the IHS, a single number adjusting for all postoperative HRQOL visits, in conjunction with predictive modelling may pose as an improved method of gauging the effect of surgical details and complications on a patient's entire recovery process. [ABSTRACT FROM AUTHOR]

To evaluate the incidence and risk factors associated with proximal junctional kyphosis (PJK) in patients with adolescent idiopathic scoliosis (AIS) after correction surgery. PubMed, Embase, and Cochrane Library were searched from inception until August 2018 to obtain relevant studies. After study selection and data extraction, statistical analysis was performed with RevMan 5.3. The odds ratios (ORs) and weight mean differences (WMDs) with 95% confidence intervals (CIs) for all available factors were analyzed using fixed or random effects models. A total of 7 studies were included in this meta-analysis. The overall incidence of PJK in AIS was 14% (95% CI, 8%–20%). Among the potential risk factors, proximal implants with screws (OR, 1.64; 95% CI, 1.13–2.39; P = 0.010), instrumentation types with all screws (OR, 1.78; 95% CI, 1.19–2.67; P = 0.005), larger preoperative thoracic kyphosis (TK) (WMD, 7.50; 95% CI, 5.75–9.26; P < 0.001), larger preoperative lumbar lordosis (LL) (WMD, 4.85; 95% CI, 2.79–6.92; P < 0.001), larger postoperative LL (WMD, 2.00; 95% CI, 0.09–3.91; P = 0.040), greater change in TK (WMD, −6.75; 95% CI, −9.72 to −3.78; P < 0.001), and greater change in LL (WMD, −3.26; 95% CI, −5.40 to −1.12; P = 0.003) were identified as risk factors for PJK. The incidence of PJK in patients with AIS was 14%. Proximal implants with screws and instrumentation types with all screws were significantly associated with increased occurrence of PJK. Larger preoperative TK, larger preoperative LL, larger postoperative LL, greater TK change, and greater LL change were also identified as risk factors for PJK in AIS after correction surgery. [ABSTRACT FROM AUTHOR]

Background This study aimed to compare radiographic outcomes of adult spinal deformity (ASD) surgery with or without 2-level prophylactic vertebroplasty (PVP) at the uppermost instrumented vertebra (UIV) and the vertebra 1 level proximal to the UIV. Methods This retrospective 1:2 matched-cohort comparative study enrolled 2 groups of patients undergoing ASD surgery, including 28 patients with PVP (PVP group) and 56 patients without PVP (non-PVP group), in 3 institutes between 2012 and 2015. The primary outcome measure was the incidence of proximal junctional kyphosis (PJK), proximal junctional failure (PJF), and proximal junctional fracture (PJFX). The secondary outcome measure were radiologic outcomes between PVP segments and non-PVP segments. Results Between the PVP group and non-PVP group, no significant differences were found in the incidence of PJK (13 [46.4%] vs. 26 [46.4%]; P = 1.000), PJF (11 [39.3%] vs. 18 [32.1%]; P = 0.516), and PJFX (11 [39.3%] vs. 18 [32.1%]; P = 0.516). The number of the PJFX segments was 16 and 33 in PVP segments and non-PVP segments, respectively. Until revision surgery or final follow-up, the PJFX had progressed in 24 non-PVP segments (82.7%), but not in PVP segments. The PJFX progression in all PVP segments stopped near the PVP mass at the final follow-up. Reoperation as a result of PJFX was performed in 1 patient (3.6%) and 8 patients (14.3%) in the PVP and non-PVP groups, respectively. Conclusions PVP at UIV and vertebra 1 level proximal to the UIV cannot prevent PJK, PJF, and PJFX; however, it plays a positive role by delaying their progression. Furthermore, PVP tends to lower the reoperation rate after PJFX in ASD surgery. [ABSTRACT FROM AUTHOR]

• A standardized neurosurgical approach was opted for best fusion outcomes accompanied by maximal infection eradication in treatment of spondylodiscitis. • The fusion rate was 92.3 %. Proximal junctional kyphosis incidence was 16.3 % and had a significant association with on-admission neurological symptoms, and thoracic and thoracolumbar junction involvements. • Patients with older age, neurological symptoms, and comorbidities are expected to experience less favorable clinical outcomes. To investigate the fusion construct properties, construct length, intervertebral prosthesis (IVP) selection, bone grafting methods, complications management, and follow-up outcomes of spondylodiscitis fusion. This case series was conducted in Al-Zahra University referral hospital from March 2016 to November 2021. All the surgery-eligible patients were enrolled. Those who did not participate or failed the neurosurgical intervention were excluded. A unified neurosurgical protocol was defined. After operation and follow-up, all variables were documented. IBM SPSS v.26 was used for data analysis. P-value ≤ 0.05 was considered significant. Ninety-two patients were reviewed in the final analysis with 65.2 % males. The mean age was 55.07 ± 14.22 years old. The most frequent level of pathology and surgery was the lumbar spine (48.9 %). Short and long constructs were almost equally used (57.6 and 42.4 %, respectively). Bone graft mixture was the dominant IVP (75 %). The most frequent persistent postoperative symptom was back pain (55.4 %), while the neurological deficits resolution rate was 76.7 %. The fusion rate was 92.3 %. Proximal junctional kyphosis incidence was 16.3 % and had a significant association with on-admission neurological symptoms, thoracic and thoracolumbar junction involvements (p < 0.05). Follow-up Oswestry disability index scores showed 44.6 % of the patients had mild or no functional disabilities. Advanced age, On-admission deficits, comorbidities, titanium cages, and poor fusion status were associated with poor functional outcomes and higher mortality rates (P < 0.05). The introduced neurosurgical protocol could effectively achieve acceptable SD treatment, spine stabilization, and fusion with low long-term surgical complications. Autologous bone graft mixture in comparison to titanium cages showed a higher fusion rate with a lower mortality rate. Patients with older age, neurological symptoms, and comorbidities are expected to experience less favorable clinical outcomes. [ABSTRACT FROM AUTHOR]

Objective The aims of this retrospective cohort study were to 1) identify new alignment risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) patients with lower thoracic upper instrumented vertebra (UIV) and 2) determine the effect of junctional tethers on PJK and UIV alignment. Methods We analyzed consecutive ASD patients who underwent posterior instrumented fusion with lower thoracic UIV (T9-T11). Posteriorly anchored junctional tethers were used more recently for ligamentous augmentation to prevent PJK. In addition to regional and global parameters, upper segmental lumbar lordosis (ULL) versus lower segmental lumbar lordosis and UIV angle (measured from UIV inferior endplate to horizontal) were assessed. Primary outcome of PJK was defined as proximal junctional angle >10° and >10° greater than the corresponding preoperative measurement. Univariable and multivariable analyses were performed. Results The study cohort comprised 120 ASD patients (mean age, 67 years) with minimum 1-year follow-up. Preoperative ULL (P = 0.034) and UIV angle (P = 0.026) were associated with PJK. No independent preoperative alignment risk factors of PJK were identified in multivariable analysis. Tether use was protective against PJK (odds ratio, 0.063 [0.016–0.247]; P < 0.001). PJK in tethered patients was more common with greater postoperative ULL (P = 0.047) and UIV angle (P = 0.026). Conclusions Junctional tethers significantly reduced PJK in ASD patients with lower thoracic UIV. In tethered patients, PJK was more common with greater postoperative lordosis of the upper lumbar spine and greater UIV angle. This finding suggests potential benefit of tethers to mitigate effects of segmental lumbar and focal UIV malalignment that may occur after deformity surgery. Highlights • No preoperative alignment risk factors of PJK were identified in multivariable analysis. • Lower thoracic junctional tethers have a protective effect against PJK. • PJK in tethered patients was more common with greater postoperative ULL and UIV angle. • Tethers may mitigate effects of segmental and focal malalignment or overcorrection. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of sublaminar polyester tension bands on the biomechanics of the motion segments proximal to a long fusion construct. Methods This was a human cadaveric biomechanical study. Pure moments of 4 Nm and 8 Nm were applied to the native spine and the instrumented spine, respectively (n = 8). The test conditions included native spine (T7–L2), fused (T10–L2), fused + bilateral tethers tensioned to 250 N at T9–T10 (tethers 250 N), fused + tethers tensioned to 350 N (tethers 350 N), fused (T11–L2) + tethers tensioned to 250 N at T9–T10 and 350 N at T10–T11 (2-level tethers), fused (T10-L2) + hand-tied suture loop through the spinous processes at T9–T10 (suture loop), and fused (T10–L2) with the T9–T10 interspinous and supraspinous ligaments cut (cut ISL/SSL). Results The flexion range of motion (ROM) at T9–T10 of the fused spine, loaded at 8 Nm, increased to 162% of the native spine loaded at 4 Nm. The average flexion ROM at T9–T10 for tethers 250 N, tethers 350 N, 2-level tethers, suture loop, and cut ISL/SSL were 85% (P < 0.0001), 70% (P < 0.0001), 93% (P < 0.0001), 141% (P = 0.13), and 177% (P = 0.66) of the native spine at 4 Nm, respectively (P values vs. fused). Conclusions Sublaminar polyester bands can modulate the biomechanical flexion ROM as a function of the band pretension and provide a more consistent and tunable technique than hand-tying a suture loop between the spinous processes. Highlights • Sublaminar polyester bands modulate the flexion ROM as a function of the band pretension. • Cutting the ISL and SSL tends to increase the flexion ROM. • Preserving and protecting the posterior ligaments from excessive flexion loading may reduce the risk of PJK. [ABSTRACT FROM AUTHOR]

Background Proximal junctional kyphosis (PJK) is a common phenomenon after long segmental fusion surgery of adolescent idiopathic scoliosis. However, the inability to reliably identify vertebral endplates on lateral upright radiographs has made an accurate measurement of proximal junctional angle (PJA) technically impossible in many patients. The aim of this study was to determine whether a grayscale inversion view is more reliable to measure PJA and to assess PJK accurately. Methods A total of 162 patients with adolescent idiopathic scoliosis who underwent posterior spinal fusion surgeries were included in this study. PJA was measured on preoperative lateral standing films using 3 methods (upper-instrumented vertebrae [UIV] + 1, UIV + 2, and UIV to T2) on both standard view and grayscale inversion view. Two physicians independently measured the PJA twice at a 1-month interval. Intra- and interobserver reliabilities were compared between the 2 radiographic views. Forty patients with preoperative magnetic resonance imaging (MRI) scans were randomly selected. PJA was measured for these patients on both views of lateral standing films and MRI images. The correlation coefficients between PJA obtained on MRI and PJA obtained on radiographs with different views were calculated respectively. Results The intraclass correlation coefficients were greater in a grayscale inversion view than in a standard view in all 3 methods for both observers, and the intraclass correlation coefficients of interobserver reliabilities also were greater in a grayscale inversion view. The correlation coefficient between PJA obtained on grayscale inversion view and preoperative MRI was greater in all methods compared with standard view. Conclusions Grayscale inversion view can be a more reliable tool for the evaluation of PJK as compared with the conventional measurement. We recommend the application of a grayscale inversion view to measure PJA and assess PJK in clinical practice, particularly for patients instrumented to the upper thoracic spine. Highlights • The inability to reliably identify vertebral endplates on lateral upright radiographs often makes a measurement of PJA. • Both the ICCs and ICCs of interobserver reliabilities were greater in a grayscale inversion view. • Grayscale inversion view can reduce the limitations of the 3 commonly used methods of measuring PJA. • We recommend applying a grayscale inversion view to assess PJK accurately, particularly for the upper thoracic spine. [ABSTRACT FROM AUTHOR]

Highlights • 21.1% of our cohort of operative CD patients had radiographic pre-operative PJK. • Patients with CD secondary to PJK had worse baseline CD. • Surgical correction of CD associated with PJK was more invasive and complicated. Abstract CD development secondary to PJK was recently documented in adult spinal deformity patients after surgical correction for thoracolumbar ASD. This study analyzes surgical management of patients with CD secondary to proximal junctional kyphosis (PJK) versus patients with primary CD. Retrospective review of multicenter cervical deformity (CD) database. CD defined as at least one of the following: C2–C7 coronal Cobb > 10°, cervical lordosis (CL) > 10°, cervical sagittal vertical axis (cSVA) > 4cm, CBVA > 25°. Patients were grouped into those with PJK (UIV +2 < −10°) prior to cervical surgery versus who don't (Non-PJK). Independent t-tests and chi-squared tests compared radiographic, clinical, and surgical metrics between PJK and non-PJK groups. Of 123 eligible CD patients, 26(21.1%) had radiographic PJK prior to cervical surgery. PJK patients had significantly greater T2–T12 thoracic kyphosis (−58.8° vs −45.0°, p = 0.002), cSVA (49.1 mm vs 38.9 mm, p = 0.020), T1 Slope (42.6° vs 28.4°, p < 0.001), TS-CL (44.1° vs 35.6°, p = 0.048), C2-T3 SVA (98.8 mm vs 75.8 mm, p = 0.015), C2 Slope (45.4° vs 36.0°, p = 0.043), and CTPA (6.4° vs 4.6°, p = 0.005). Comparing their surgeries, the PJK group had significantly more levels fused (10.7 vs 7.4, p = 0.01). There was significantly greater blood loss in PJK patients (1158 ± 1063vs 738 ± 793 cc, p = 0.028); operative time, surgical approach, and BMP-2 use were similar (all p > 0.05). PJK patients experienced higher rates of complications 30 and 90 days post-operatively (23.1% vs. 5.2%, p = 0.004; 30.8% vs. 19.6%, p = 0.026), and more instrumentation failure 30 days postoperatively (7.8% vs. 1.0%, p = 0.004). Patients with cervical deformity secondary to PJK had worse baseline CD, despite no differences in HRQL or demographics. Surgical correction of CD associated with PJK required more invasive surgery and had higher complication rates than non-PJK patients, despite achieving similar clinical outcomes. [ABSTRACT FROM AUTHOR]

Background Context: The incidence of proximal junctional kyphosis (PJK) ranges from 5% to 46% following adult spinal deformity surgery. Approximately 66% to 76% of PJK occurs within 3 months of surgery. A subset of these patients, reportedly 26% to 47%, develop proximal junctional failure (PJF) within 6 months postoperatively. To date, there are no studies evaluating the impact of prophylactic vertebroplasty on PJK and PJF incidence at long-term follow-up.Purpose: The purpose of this study is to evaluate the long-term radiographic and clinical outcomes, and incidence of PJK and PJF, after prophylactic vertebroplasty for long-segment thoracolumbar posterior spinal fusion (PSF).Study Design: This is a prospective cohort study.Patient Sample: Thirty-nine patients, of whom 87% were female, who underwent two-level prophylactic vertebroplasty at the upper instrumented and supra-adjacent vertebrae at the time of index PSF were included in this study.Outcome Measures: Clinical outcomes were assessed using the Scoliosis Research Society-22 (SRS-22), and Short-Form (SF) 36 questionnaires, and the Oswestry Disability Index (ODI). Radiographic parameters including PJK angle, and coronal and sagittal alignment, were calculated, along with relevant perioperative complications and revision rates.Methods: Of the 41 patients who received two-level prophylactic vertebroplasty at the upper instrumented and supra-adjacent vertebrae at the time of index PSF, and comprised a cohort with previously published 2-year follow-up data, 39 (95%) completed 5-year follow-up (average: 67.6 months). Proximal junctional kyphosis was defined as a change in the PJK angle ≥10° between the immediate postoperative and final follow-up radiograph. Proximal junctional failure was defined as acute proximal junctional fracture, fixation failure, or kyphosis requiring extension of fusion within the first 6 months postoperatively.Results: Thirty-nine patients with a mean age of 65.6 (41-87) years were included in this study. Of the 39 patients, 28.2% developed PJK (11: 7.7% at 2 years, 20.5% between 2 and 5 years), and 5.1% developed acute PJF. Two of the 11 PJK patients required revision for progressive worsening of the PJK. There were no proximal junctional fractures. There was no significant difference in preoperative, immediate postoperative, and final follow-up measurements of thoracic kyphosis, lumbar lordosis, and coronal or sagittal alignment between patients who developed PJK, PJF, or neither (p>.05). There was no significant difference in ODI, SRS-22, or SF-36 scores between those with and without PJK or PJF (p>.05).Conclusions: This long-term follow-up demonstrates that prophylactic vertebroplasty may minimize the risk for junctional failure in the early postoperative period. However, it does not appear to decrease the incidence of PJK at 5 years. [ABSTRACT FROM AUTHOR]

Background Context: Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are common problems after long-segment (>5 levels) thoracolumbar instrumented fusions in the treatment of adult spinal deformity (ASD). No specific surgical strategy has definitively been shown to lower the risk of PJK as the result of a multifactorial etiology.Purpose: The study aimed to assess the incidence of PJK and PJF in patients treated with prophylactic polymethylmethacrylate (PMMA) cement augmentation at the uppermost instrumented vertebrae (UIV) and rostral adjacent vertebrae (UIV+1).Study Design/setting: This is a retrospective cohort-matched surgical case series at an academic institutional setting.Patient Sample: Eighty-five adult patients over a 16-year enrollment period were identified with long-segment (>5 levels) posterior thoracolumbar instrumented fusions for ASD.Outcome Measures: Primary outcomes measures were PJK magnitude and PJF formation. Secondary outcomes measures were spinopelvic parameters, as well as global and regional sagittal alignment.Methods: The impact of adjunctive PMMA use in long-segment (≥5 levels) fusion for ASD was assessed in adult patients aged 18 and older. Patients were included with at least one of the following: lumbar scoliosis >20°, pelvic tilt >25°, sagittal vertical axis >5 cm, central sacral vertical line >2 cm, and thoracic kyphosis >60°. The frequency of PJF and the magnitude of PJK were measured radiographically preoperatively, postoperatively, and at maximum follow-up in controls (Group A) and PMMA at the UIV and UIV+1 (Group B).Results: Eighty-five patients (64±11.1 years) with ASD were identified: 47 control patients (58±10.6) and 38 patients (71±6.8) treated with PMMA at the UIV and UIV+1. The mean follow-up was 27.9 and 24.2 months in Groups A and B, respectively (p=.10). Preoperative radiographic parameters were not significantly different, except the pelvic tilt which was greater in Group A (26.6° vs. 31.4°, p=.03). Postoperatively, the lumbopelvic mismatch was greater in Group B (14.6° vs. 7.9°, p=.037), whereas the magnitude of PJK was greater in controls (9.36° vs. 5.65°, p=.023). The incidence of PJK was 36% (n=17) and 23.7% (n=9) in Groups A and B, respectively (p=.020). The odds ratio of PJK with vertebroplasty was 0.548 (95% confidence interval=0.211 to 1.424). Proximal junctional kyphosis was observed in 6 (12.8%) controls only (p=.031). The UIV+1 angle, a measure of PJK, was significantly greater in controls (10.0° vs. 6.8°, p=.02). No difference in blood loss was observed. No complications were attributed to PMMA use.Conclusions: The use of prophylactic vertebral cement augmentation at the UIV and rostral adjacent vertebral segment at the time of deformity correction appears to be preventative in the development of proximal junctional kyphosis and failure. [ABSTRACT FROM AUTHOR]

Objective To determine the optimal proximal fusion level after long instrumented fusion to the sacrum for lumbar degenerative flat back. Methods Data from 70 patients with lumbar degenerative flat back were reviewed retrospectively. Three groups were designated according to the upper instrumented vertebrae (UIV): group 1 (UIV = T10 or above), group 2 (UIV = T11-12), and group 3 (UIV = L1 or below). Pre- and postoperative pelvic parameters, degree of correction, and prevalence of proximal junctional kyphosis (PJK) and its risk factors were evaluated. Results The prevalence of PJK was 27.1% (average 35.5 months of follow-up). Preoperative pelvic incidence (PI) and sacral slope (SS) in group 1 were higher in the PJK group than in the non-PJK group ( P = 0.03 and P = 0.001, respectively). Preoperative thoracolumbar (TL) in group 3 was higher in the PJK group than in the non-PJK group ( P = 0.01). Postoperative pelvic tilt (PT) was lower (<20°) in the non-PJK group than in the PJK group ( P = 0.025 in group 3). Postoperative TL in group 3 was lower than in the non-PJK group ( P = 0.024). Conclusions If the PI is ≥50°, TL kyphosis is ≥5°, and SS is ≥20°, the UIV should be raised above T10 up to the midthoracic level. If the PI is ≥50°, SS is ≤20°, and thoracic kyphosis (TK) is normal despite TL kyphosis, the UIV should be at T10. Even if the PI is ≥50°, TK is normal, and there is no TL kyphosis, the UIV should be set at L1 or below. Regardless of the UIV, the postoperative PT should be ≤20°. [ABSTRACT FROM AUTHOR]

Background Context: Proximal junctional kyphosis (PJK) is a challenging complication after rigid posterior instrumentation (RI) of the spine. Several risk factors have been described in literature so far, including the rigidity of the cranial aspect of the implant.Purpose: The aim of this biomechanical study was to compare different proximal implants designed to gradually reduce the stiffness between the instrumented and non-instrumented spine.Study Design/setting: This is a biomechanical study.Methods: Eight calf lumbar spines (L2-L6) underwent RI with a titanium pedicle screw rod construct at L4-L6. The proximal transition segment (L3-L4) was instrumented stepwise with different supplementary implants-spinal bands (SB), cerclage wires (CW), hybrid rods (HR), hinged pedicle screws (HPS), or lamina hooks (LH)-and compared with an all-pedicle screw construct (APS). The flexibility of each segment (L2-L6) was tested with pure moments of ±10.0 Nm in the native state and for each implant at L3-L4, and the segmental range of motion (ROM) was evaluated.Results: On flexion and extension, the native uninstrumented L3-L4 segment showed a mean ROM of 7.3°. The CW reduced the mean ROM to 42.5%, SB to 41.1%, HR to 13.7%, HPS to 12.3%, LH to 6.8%, and APS to 12.3%. On lateral bending, the native segment L3-L4 showed a mean ROM of 15°. The CW reduced the mean ROM to 58.0%, SB to 78.0%, HR to 6.7%, HPS to 6.7%, LH to 10.0%, and APS to 3.3%. On axial rotation, the uninstrumented L3-L4 segment showed a mean ROM of 2.7°. The CW reduced the mean ROM to 55.6%, SB to 77.8%, HR to 55.6%, HPS to 55.6%, LH to 29.6%, and APS to 37.0%.Conclusions: Using CW or SB at the proximal transition segment of a long RI reduced rigidity by about 60% in relation to flexion and extension in that segment, whereas the other implants tested had a high degree of rigidity comparable with APS. Clinical randomized controlled trials are needed to elucidate whether this strategy might be effective for preventing PJK. [ABSTRACT FROM AUTHOR]

Background Context: Little is known about the effect of rod stiffness as a risk factor of proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery.Purpose: The aim of this study was to compare radiographic outcomes after the use of cobalt chrome multiple-rod constructs (CoCr MRCs) and titanium alloy two-rod constructs (Ti TRCs) for ASD surgery with a minimum 1-year follow-up.Study Design: Retrospective case-control study in two institutes.Patient Sample: We included 54 patients who underwent ASD surgery with fusion to the sacrum in two academic institutes between 2002 and 2015.Outcome Measures: Radiographic outcomes were measured on the standing lateral radiographs before surgery, 1 month postoperatively, and at ultimate follow-up. The outcome measures were composed of pre- and postoperative sagittal vertical axis (SVA), pre- and postoperative lumbar lordosis (LL), pre- and postoperative thoracic kyphosis (TK)+LL+pelvic incidence (PI), pre- and postoperative PI minus LL, level of uppermost instrumented vertebra (UIV), evaluation of fusion after surgery, the presence of PJK, and the occurrence of rod fracture.Materials and Methods: We reviewed the medical records of 54 patients who underwent ASD surgery. Of these, 20 patients had CoCr MRC and 34 patients had Ti TRC. Baseline data and radiographic measurements were compared between the two groups. The Mann-Whitney U test, the chi-square test, and the Fisher exact test were used to compare outcomes between the groups.Results: The patients of the groups were similar in terms of age, gender, diagnosis, number of three-column osteotomy, levels fused, bone mineral density, preoperative TK, pre- and postoperative TK+LL+PI, SVA difference, LL change, pre- and postoperative PI minus LL, and location of UIV (upper or lower thoracic level). However, there were significant differences in the occurrence of PJK and rod breakage (PJK: CoCr MRC: 12 [60%] vs. Ti TRC: 9 [26.5%], p=.015; occurrence of rod breakage: CoCr MRC: 0 [0%] vs. Ti TRC: 11 [32.4%], p=.004). The time of PJK was less than 12 months after surgery in the CoCr MRC group. However, 55.5% (5/9) of PJK developed over 12 months after surgery in the Ti TRC group.Conclusions: Increasing the rod stiffness by the use of cobalt chrome rod and can prevent rod breakage but adversely affects the occurrence and the time of PJK. [ABSTRACT FROM AUTHOR]

Background Context: Multiple methods are used to measure proximal junctional angle (PJA) and diagnose proximal junctional kyphosis (PJK) after fusion for adolescent idiopathic scoliosis (AIS); however, there is no gold standard. Previous studies using the three most common measurement methods, upper-instrumented vertebra (UIV)+1, UIV+2, and UIV to T2, have minimized the difficulty in obtaining these measurements, and often exclude patients for which measurements cannot be recorded.Purpose: The purpose of this study is to assess the technical feasibility of measuring PJA and PJK in a series of AIS patients who have undergone posterior instrumented fusion and to assess the variability in results depending on the measurement technique used.Study Design/setting: A retrospective cohort study was carried out.Patient Sample: There were 460 radiographs from 98 patients with AIS who underwent posterior spinal fusion at a single institution from 2006 through 2012.Outcome Measures: The outcomes for this study were the ability to obtain a PJA measurement for each method, the ability to diagnose PJK, and the inter- and intra-rater reliability of these measurements.Methods: Proximal junctional angle was determined by measuring the sagittal Cobb angle on preoperative and postoperative lateral upright films using the three most common methods (UIV+1, UIV+2, and UIV to T2). The ability to obtain a PJA measurement, the ability to assess PJK, and the total number of patients with a PJK diagnosis were tabulated for each method based on established definitions. Intra- and inter-rater reliability of each measurement method was assessed using intra-class correlation coefficients (ICCs).Results: A total of 460 radiographs from 98 patients were evaluated. The average number of radiographs per patient was 5.3±1.7 (mean±standard deviation), with an average follow-up of 2.1 years (780±562 days). A PJA measurement was only readable on 13%-18% of preoperative filmsand 31%-49% of postoperative films (range based on measurement technique). Only 12%-31% of films were able to be assessed for PJK based on established definitions. The rate of PJK diagnosis ranged from 1% to 29%. Of these diagnoses, 21%-100% disappeared on at least one subsequent film for the given patient. ICC ranges for intra-rater and inter-rater reliability were 0.730-0.799 and 0.794-0.836, respectively.Conclusions: This study suggests significant limitations of the three most common methods of measuring and diagnosing PJK. The results of studies using these methods can be significantly affected based on the exclusion of patients for whom measurements cannot be made and choice of measurement technique. [ABSTRACT FROM AUTHOR]

Objective A meta-analysis was performed to compare incidence rates of radiographic and surgical proximal junctional kyphosis (PJK) between upper thoracic (UT) and lower thoracic (LT) vertebrae as site of upper instrumented vertebrae (UIV) endpoints for long fusion surgery in adult spinal deformity (ASD). Methods MEDLINE, Embase, and Cochrane Library databases were searched for English-language articles that addressed UT versus LT fixation strategies. The division of the UT and LT groups was based on UIV. Two reviewers independently assessed the quality of the studies using the Newcastle-Ottawa Scale. Data on incidence rates of radiographic and surgical PJK were extracted from the included studies. RevMan 5.3 was used for data pooling and analysis. Results Ten retrospective studies comprising 1230 patients were included. Pooled data on radiographic PJK were available in 9 studies comprising 1032 patients, and total radiographic PJK rate was 32.2%. Pooled data on surgical PJK were available in 6 studies comprising 732 patients, and total surgical PJK rate was 6.7%. Decreased radiographic PJK (95% confidence interval, 0.49–0.85; P = 0.002; I 2 = 48%) and surgical PJK (95% confidence interval, 0.18–0.76; P = 0.007; I 2 = 22%) were found in the UT group. Conclusions Radiographic PJK is a very common complication of long fusion surgery in adult spinal deformity with an incidence rate of 32.2%. Surgical PJK has an incidence rate of 6.7% and should be seriously considered. The pooled results indicate that choosing UT vertebrae as the site of UIV could decrease the incidence rates of radiographic and surgical PJK. [ABSTRACT FROM AUTHOR]

Introduction Evidence regarding whether the polyaxial pedicle screws at the upper instrumented vertebrae (UIV) are superior to monoaxial pedicle screws in prevention of proximal junctional kyphosis (PJK) is not clear. The aim of this study was therefore to explore the influence of different types of pedicle screws at UIV on the incidence of PJK. Methods We reviewed retrospectively 242 patients surgically treated with instrumented segmental posterior spinal fusion at a minimum of 4 motion segments. Polyaxial pedicle screws were used at UIV in 125 patients (polyaxial group), and monoaxial pedicle screws were used at UIV in 117 patients (monoaxial group). According to the occurrence of PJK at final follow-up, patients in both the polyaxial and monoaxial groups were then divided into 2 subgroups: PJK and no proximal junctional kyphosis (NPJK). To investigate the risk factors of PJK, 2 categorized variables were analyzed statistically: 1) patient characteristics: age, sex, body mass index (BMI), bone mineral density (BMD), sagittal vertical axis (SVA), thoracic kyphosis, thoracolumbar junctional angle, lumbar lordosis (LL), pelvic incidence, pelvic tilt, and sacral slope. 2) Surgical variables: Changes of radiographic parameters include the SVA, thoracic kyphosis, thoracolumbar junctional, LL, pelvic incidence, pelvic tilt, sacral slope, pedicle-upper end plate angle, the number of instrumented levels, and the most proximal and distal levels of the instrumentation. Results PJK was developed in 26 of 117 patients (22.2%) in the monoaxial group and 30 of 125 patients (24.0%) in the polyaxial group. Until the final follow-up, there was no significant difference in the incidence of PJK (χ2 = 0.107, P = 0.734) between the monoaxial and polyaxial groups. There was no significant difference in patient characteristics and surgical variables between the 2 groups, except the proximal junctional angle change ( P = 0.031). In the monoaxial group, there were no significant differences in patient characteristics between the PJK and NPJK subgroups, except BMI ( P = 0.042) and BMD ( P = 0.037). There were no significant differences in change of radiographic parameters, except SVA change ( P = 0.036), proximal junctional angle change ( P = 0.029), LL change ( P = 0.025), and lower instrumented vertebrae location ( P = 0.036). Multivariate logistic regression analysis revealed that obesity, osteoporosis, lower instrumented vertebra at sacrum, and LL change >10 degrees were independently associated with PJK. In the polyaxial group, there were no significant differences in patient characteristics between the PJK and NPJK subgroups, except BMI ( P = 0.032) and BMD ( P = 0.040). There were no significant differences in change of radiographic parameters between the PJK and NPJK subgroups, except P-UP angle ( P = 0.037) and lower instrumented vertebrae location ( P = 0.017). Multivariate logistic regression analysis revealed that obesity, osteoporosis, and lower instrumented vertebra at sacrum were independently associated with PJK. Conclusions Polyaxial pedicle screws at UIV is not superior to monoaxial pedicle screws in prevention of PJK. Obesity, osteoporosis, and lower instrumented vertebra at sacrum are risk factors for PJK in all the patients. Excessive LL reconstruction is the unique risk factor of PJK when monoaxial pedicle screws were used at UIV. [ABSTRACT FROM AUTHOR]

Proximal junctional failure is a common complication attributed to the rigidity of long pedicle screw fixation constructs used for surgical correction of adult spinal deformity. Semi-rigid junctional fixation achieves a gradual transition in range of motion at the ends of spinal instrumentation, which could lead to reduced junctional stresses, and ultimately reduce the incidence of proximal junctional failure. This study investigates the biomechanical effect of different semi-rigid junctional fixation techniques in a T8-L3 finite element spine segment model. First, degeneration of the intervertebral disc was successfully implemented by altering the height. Second, transverse process hooks, one- and two-level clamped tapes, and one- and two-level knotted tapes instrumented proximally to three-level pedicle screw fixation were validated against ex vivo range of motion data of a previous study. Finally, the posterior ligament complex forces and nucleus pulposus stresses were quantified. Simulated range of motions demonstrated the fidelity of the general model and modelling of semi-rigid junctional fixation techniques. All semi-rigid junctional fixation techniques reduced the posterior ligament complex forces at the junctional zone compared to pedicle screw fixation. Transverse process hooks and knotted tapes reduced nucleus pulposus stresses, whereas clamped tapes increased nucleus pulposus stresses at the junctional zone. The relationship between the range of motion transition and the reductions in posterior ligament complex and nucleus pulposus stresses was complex and dependent on the fixation techniques. Clinical trials are required to compare the effectiveness of semi-rigid junctional fixation techniques in terms of reducing proximal junctional failure incidence rates. • Degenerative changes of the intervertebral disc are implemented in a spinal finite element model. • Transition of spinal stresses and range of motion are not always proportional. • Ex vivo results of the instrumented spine are in agreement with the in silico model. [ABSTRACT FROM AUTHOR]

Objective To evaluate spinal implant density and proximal junctional kyphosis (PJK) in adult spinal deformity (ASD). Methods Consecutive patients with ASD receiving ≥5 level fusions were retrospectively analyzed between 2007 and 2010. Inclusion criteria: ASD, elective fusions, minimum 2-year follow-up. Exclusion criteria: age <18 years, neuromuscular or congenital scoliosis, cervical or cervicothoracic fusions, nonelective conditions (infection, tumor, trauma). Instrumented fusions were classified by the Scoliosis Research Society–Schwab ASD classification. Statistical analysis consisted of descriptives (measures of central tendency, dispersion, frequencies), independent Student t tests, χ 2 , analysis of variance, and logistic regression to determine association of implant density [(number of screws + number of hooks)/surgical levels of fusion] and PJK. Mean and median follow-up was 2.8 and 2.7 years, respectively. Results Eighty-three patients (17 male, 66 female) with a mean age of 59.7 years (standard deviation, 10.3) were analyzed. Mean body mass index (BMI) was 29.5 kg/m 2 (range, 18–56 kg/m 2 ) with mean preoperative Oswestry Disability Index of 48.67 (range, 6–86) and mean preoperative sagittal vertical axis of 8.42. The mean levels fused were 9.95 where 54 surgeries had interbody fusion. PJK prevalence was 21.7%, and pseudoarthrosis was 19.3%. Mean postoperative Oswestry Disability Index was 27.4 (range, 0–74). Independent Student t tests showed that PJK was not significant for age, gender, BMI, rod type, mean postoperative sagittal vertical axis, or Scoliosis Research Society–Schwab ASD classification; but iliac fixation approached significance ( P = 0.077). Implant density and postoperative lumbar lordosis (LL) were predictors for PJK ( P = 0.018 and 0.045, respectively). Controlling for age, BMI, and gender, postoperative LL (not implant density) continued to show significance in multivariate logistic regression model. Conclusions PJK, although influenced by a multitude of factors, may be statistically related to implant density and LL. [ABSTRACT FROM AUTHOR]

Background Context: There are several reports regarding pathogeneses and risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity surgery. However, the relationship between thoracolumbar muscle condition and PJK has not been investigated yet.Purpose: We aimed to elucidate the thoracolumbar muscle conditions on the incidence of PJK in adult patients with spinal deformity treated by long instrumented spinal fusion surgery stopping at thoracolumbar junction with a minimum 2-year follow-up (F/U).Study Design: This is a retrospective review of prospective database.Patient Sample: A total of 44 cases of patients having multilevel spinal instrumented fusion stopping at thoracolumbar junction for adult spinal deformity in two academic institutions from 2004 to 2012 were enrolled in this study.Outcome Measures: For clinical outcomes, the Scoliosis Research Society questionnaire-22r (SRS-22r) was used preoperatively and at ultimate F/U.Methods: Inclusion criteria were age >20 and minimum five vertebrae fused from T9 upper instrumented vertebra (UIV) to any lower instrumented vertebra. Radiographic assessment included pelvic parameters, Cobb measurements in the coronal-sagittal plane, and measurements of the thoracolumbar muscularity (cross-sectional area of muscle-vertebral body ratio×100) and fatty degeneration (signal intensity of muscle-subcutaneous fat ratio×100).Results: The prevalence of PJK was 38.6%. Age at surgery, gender, fusions extending to the sacrum, levels fused, combined anterior-posterior surgery, and a UIV level were not significantly different between PJK and non-PJK groups. Lower bone mineral density (BMD; T-score: -2.5 vs. -1.3, p=.003) and lower muscularity and higher fatty degeneration at the level of T10 to L2 (131.8 vs. 159.0, p<.01; 59.0 vs. 44.0, p<.001, respectively) were identified risk factors for PJK. Radiographic parameters demonstrated a higher postoperative lumbar lordosis (LL) change (43.8 vs. 29.3, p<.001) and a larger sagittal vertical axis (SVA) change with surgery (8.4 cm vs. 4.8 cm, p=.01) in those with PJK. Although SRS postop pain scores were inferior in PJK group (3.3 vs. 4.1, p<.05), there were no significant differences in the average scores between the groups (3.5 vs. 3.3, p<.05).Conclusions: Patients with PJK had lower thoracolumbar muscularity and higher fatty degeneration than patients without PJK before surgery. Our data suggest that osteoporosis, large corrections in LL and SVA with surgery, and lower muscularity and higher fatty degeneration at the thoracolumbar area can lead to PJK. [ABSTRACT FROM AUTHOR]

Background Spinal fusion surgery is a widely used surgical procedure for sagittal realignment. Clinical studies have reported that spinal fusion may cause proximal junctional kyphosis and failure with disc failure, vertebral fracture, and/or failure at the implant-bone interface. However, the biomechanical injury mechanisms of proximal junctional kyphosis and failure remain unclear. Methods A finite element model of the thoracolumbar spine was used. Nine fusion models with pedicle screw systems implanted at the L2–L3, L3–L4, L4–L5, L5–S1, L2–L4, L3–L5, L4–S1, L2–L5, and L3–S1 levels were developed based on the respective surgical protocols. The developed models simulated flexion–extension using hybrid testing protocol. Findings When spinal fusion was performed at more distal levels, particularly at the L5–S1 level, the following biomechanical properties increased during flexion–extension: range of motion, stress on the annulus fibrosus fibers and vertebra at the adjacent motion segment, and the magnitude of axial forces on the pedicle screw at the uppermost instrumented vertebra. Interpretations The results of this study demonstrate that more distal fusion levels, particularly in spinal fusion including the L5–S1 level, lead to greater increases in the risk of proximal junctional kyphosis and failure, as evidenced by larger ranges of motion, higher stresses on fibers of the annulus fibrosus and vertebra at the adjacent segment, and higher axial forces on the screw at the uppermost instrumented vertebra in flexion–extension. Therefore, fusion levels should be carefully selected to avoid proximal junctional kyphosis and failure. [ABSTRACT FROM AUTHOR]

Background Context: Proximal junctional failure (PJF) is a recognized complication of spinal deformity surgery. Acute PJF (APJF) has recently been demonstrated to be 5.6% in the adult spinal deformity (ASD) population. The incidence and rate of return to the operating room for APJF have not been specifically investigated in individuals with sagittal imbalance.Purpose: The purpose of this study was to report the incidence of APJF in patients with preoperative sagittal imbalance and the rate of return to the operating room for APJF.Study Design/setting: This study is based on a retrospective review of prospectively collected database of ASD patients.Patient Sample: One hundred seventy-three consecutive patients were included with preoperative sagittal imbalance according to one of the following common parameters: sagittal vertical axis (SVA) greater than 50 mm, global sagittal alignment greater than 45°, or pelvic incidence minus lumbar lordosis greater than 10°.Outcome Measures: Outcome measure was presence and/or absence of APJF defined as fracture at the upper instrumented vertebra (UIV) or UIV+1, failure of UIV fixation, 15° or more proximal junctional kyphosis, or need for extension of instrumentation within 6 months of surgery.Methods: We performed radiographic measurements on X-rays at preoperative, immediate postoperative, and 6-month follow-up visits. The APJF rate was reported for the entire patient population with preoperative sagittal imbalance. Acute PJF incidence was calculated postoperatively for each of the accepted sagittal balance parameters and/or formulas. Patients with persistent postoperative sagittal imbalance were compared with the sagittally balanced group. We also assessed for threshold values.Results: Acute PJF was observed in 60 of 173 patients (35%) and was least common in fusions with the UIV in the upper thoracic (UT) spine (p=.035). Of those who developed APJF, 21.7% required surgery. Proximal junctional kyphosis 15° or more was the most common form of APJF in fusions to the UT spine but least likely to need revision (p=.014). The most common mode of failure in lower thoracic (LT) or lumbar (L) fusions was UIV fracture. Postoperative SVA less than 50 mm was a significant risk factor for APJF (p=.009).Conclusions: Acute PJF is more common in patients with preoperative sagittal imbalance (35%) than the general adult deformity patient population, and 37% of those with APJF require revision. It is least common when the UIV is in the UT spine, compared with the LT or L spine. Sagittal balance correction to an SVA 50 mm or less was a significant risk factor in patients with preoperative sagittal imbalance. [ABSTRACT FROM AUTHOR]

Abstract: Study design: A retrospective analysis of 150 adolescents who underwent spinal fusion for idiopathic scoliosis. Objective: To analyse the incidence of the postoperative proximal junctional kyphosis after posterior fusion to the upper thoracic vertebra in adolescents with idiopathic scoliosis and to explore its risk factors. Summary of background data: The reported incidence of the proximal junctional kyphosis after the posterior fusion in patients with idiopathic scoliosis varies depending on surgical methods and strategies adopted by the institution. Methods: The changes in the Cobb angle of the proximal junctional kyphosis on the lateral spine X-ray were measured and the presence of PJK was recorded. The risk factors were screened using statistical analysis. Results: PJK occurred in 35 out of 123 patients with an overall incidence of 28%. Among them, 28 patients (80%) experienced PJK within 1.5 years after surgery. The PJK-inducing factors included greater than 10° intraoperative decrease in thoracic kyphosis, thoracoplasty, the use of a pedicle screw at the top vertebra, autogenous bone graft and fusion to the lower lumbar vertebra (below L2). Conclusions: There is a high incidence of postoperative proximal junctional kyphosis after posterior fusion to the upper thoracic vertebra within 1.5 years after surgery in adolescents with idiopathic scoliosis. In order to reduce its incidence, the risk factors for PJK should be carefully evaluated before surgery. [Copyright &y& Elsevier]

Proximal junctional kyphosis (PJK) is a widely recognized complication of adult spinal deformity surgery, and various PJK prevention strategies have been reported in recent years. The goal of the present study was to perform a systematic review of the PJK prevention strategies, report on their effectiveness, and delineate future directions for investigation regarding PJK prevention. A systematic review was conducted using PubMed, Embase, and Scopus to identify studies examining PJK prevention techniques. The titles and abstracts were screened, and those studies progressing to the full text review were screened using prespecified inclusion and exclusion criteria. The studies were organized thematically for analysis. The search identified a total of 382 studies, 23 of which were included. The overall quality of evidence was level III. The reported PJK prevention strategies included optimization of postoperative sagittal alignment by avoiding over- or undercorrection, prophylactic vertebral cement augmentation, the use of a transverse process hook at upper instrumented vertebra, the use of more flexible rod constructs, novel pedicle screw insertion techniques, the use of junctional tethers, and teriparatide therapy, which seemed to reduce the PJK rates. The reports of PJK prevention strategies were heterogeneous, and high-level evidence regarding any particular technique remains limited. Further development of additional PJK prevention techniques and validation of their efficacy in clinical practice are needed to optimize the outcomes of adult spinal deformity surgery. [ABSTRACT FROM AUTHOR]

Objective The goal of this study is to analyze the safety and efficacy of a novel technique of computed tomography–guided, fluoroscopy-free vertebroplasty as an adjunct to help prevent proximal junction kyphosis (PJK) in long-segment posterior spinal fusions. Methods We performed a retrospective analysis of 118 consecutive patients with adult spinal deformity who underwent long-segment fusion with vertebroplasty augmentation from 2013–2016 at a single institution. For each patient, we collected demographics, surgical information, length of stay, discharge disposition, and complications, including reoperation, PJK, and PJK requiring reoperation. We reviewed all postoperative radiographs to assess for cement leakage from vertebroplasty. These patients were compared to a historical control of 253 patients who underwent adult spinal deformity surgery without vertebroplasty augmentation. Results The PJK rate of 14% and the PJK requiring reoperation rate of 3% in the cohort of 118 patients who underwent vertebroplasty-augmented fusion was significantly lower than that of the 253 historical controls at our institution who did not undergo vertebroplasty (40% PJK rate, 17% PJK-rate requiring reoperation; both P < 0.001). After controlling for patient and other surgical factors in multivariate analyses, vertebroplasty was significantly associated with lower rates of PJK and PJK requiring reoperation ( P < 0.001 and P = 0.003). Conclusions Our novel vertebroplasty technique is safe, and it eliminates the need for additional fluoroscopy in cases already using the O-arm to verify screw placement. In addition, it is an effective technique for reducing PJK in adult spinal deformity surgery compared with historical institutional controls. [ABSTRACT FROM AUTHOR]