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Background and Objectives: We sought to compare long-term clinical and radiographic outcomes in patients who underwent staged vs same-day circumferential minimally invasive surgery (cMIS) for adult spinal deformity (ASD)., Methods: We reviewed staged and same-day cMIS ASD cases in a prospective multi-institution database to compare preoperative and 2-year clinical and radiographic parameters between cohorts., Results: A total of 85 patients with a 2-year follow-up were identified (27 staged, 58 same-day). Staged patients had more extensive surgeries and greater hospital length of stay (all P < .001). There were no significant differences in preoperative or 2-year postoperative clinical metrics between cohorts. Patients in the staged cohort also had greater preoperative coronal deformity and thus experienced greater reduction in coronal deformity at 2 years (all P < .01)., Conclusion: Patients undergoing staged or same-day cMIS correction had similar outcomes at 2 years postoperatively. Staged cMIS ASD correction may be more appropriate in patients with greater deformity, higher frailty, and who require longer, more extensive surgeries., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Objective: This study evaluates the impact of L4-L5 minimally invasive surgery (MIS)- transforaminal lumbar interbody fusion (TLIF) on adjacent-level parameters., Methods: This is a retrospective study performed on consecutive patients between January 2015 and December 2019. The index- and adjacent-level segmental lordosis (SL) and disc angle (DA) were measured. Patient-reported outcomes (PROs) were collected preoperatively and at 3-24 months postoperatively. Factors influencing changes in adjacent-level parameters and the occurrence of adjacent segment degeneration (ASDeg) were assessed., Results: A total of 117 adult patients, averaging 65.5 years of age and slight preponderance of female (56.4%), were analyzed. L4-L5 SL decreased at 2 years (P < 0.05), but L4-L5 DA significantly increased at all timepoints (P < 0.05). While L3-L4 SL and DA significantly decreased at all timepoints (P < 0.05), L5-S1 SL decreased at 3 and 12 months (P < 0.05) and L5-S1 DA only significantly decreased at 2 years (P < 0.05). All PROs improved significantly (P < 0.0001). The ASDeg rate was 19.7% at 2.2 years. Cephalad and caudal ASDeg rates were 12.0% and 10.3%, respectively. Eight patients (6.8%) required adjacent-level reoperations, mainly at L3-L4 (6 cases). The use of expandable cage significantly reduced the odds of caudal ASDeg (OR 0.15, P = 0.037), but had no significant effect on cephalad ASDeg., Conclusions: L4-L5 MIS-TLIF had a more consistent effect on L3-L4 than L5-S1. Although adjacent-level SL and DA decreased over time, their association with ASDeg appears limited, suggesting a multifactorial etiology. L4-L5 MIS-TLIF provides demonstrable clinical benefits with lasting PRO improvements and low adjacent-level reoperations., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background and Objectives: Studies have demonstrated increased risk of adjacent segment disease (ASD) after open fusion with adjacent-level laminectomy, with rates ranging from 16%-47%, potentially related to disruption of the posterior ligamentous complex. Minimally invasive surgical (MIS) approaches may offer a more durable result. We report institutional outcomes of simultaneous MIS transforaminal lumbar interbody fusion (MISTLIF) and adjacent-level laminectomy for patients with low grade spondylolisthesis and ASD., Methods: Retrospective analysis was performed on patients who underwent MISTLIF with adjacent level laminectomy to treat grade I-II spondylolisthesis with adjacent stenosis at a single institution from 2007-2022., Results: A total of 34 patients met criteria, with mean follow-up of 23.1 months. In total, 37 levels were fused and 45 laminectomies performed. In this group, 21 patients received a single level laminectomy and single-level MISTLIF, 10 patients received a 2-level laminectomy and single-level MISTLIF, 2 patients received a single-level laminectomy and 2-level MISTLIF, and 1 patient received a 2-level laminectomy and 2-level MISTLIF. Three (8.8%) patients experienced clinically significant postoperative ASD requiring reoperation. Three other patients required reoperation for other reasons. Multiple logistic regression did not reveal any association between development of ASD and surgical covariates., Conclusion: MISTLIF with adjacent-level laminectomy demonstrated a favorable safety profile with rates of postoperative ASD lower than published rates after open fusion and on par with the published rates of ASD from MISTLIF alone. Future prospective studies may better elucidate the durability of adjacent-level laminectomies when performed alongside MISTLIF, but retrospective data suggests it is safe and durable., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: Depression has been implicated with worse immediate postoperative outcomes in adult spinal deformity (ASD) correction, yet the specific impact of depression on those patients undergoing minimally invasive surgery (MIS) requires further clarity. This study aimed to evaluate the role of depression in the recovery of patients with ASD after undergoing MIS., Methods: Patients who underwent MIS for ASD with a minimum postoperative follow-up of 1 year were included from a prospectively collected, multicenter registry. Two cohorts of patients were identified that consisted of either those affirming or denying depression on preoperative assessment. The patient-reported outcome measures (PROMs) compared included scores on the Oswestry Disability Index (ODI), numeric rating scale (NRS) for back and leg pain, Scoliosis Research Society Outcomes Questionnaire (SRS-22), SF-36 physical component summary, SF-36 mental component summary (MCS), EQ-5D, and EQ-5D visual analog scale., Results: Twenty-seven of 147 (18.4%) patients screened positive for preoperative depression. The nondepressed cohort had an average of 4.83 levels fused, and the depressed cohort had 5.56 levels fused per patient (p = 0.267). At 1-year follow-up, 10 patients still reported depression, representing a 63% decrease. Postoperatively, both cohorts demonstrated improvement in their PROMs; however, at 1-year follow-up, those without depression had statistically better outcomes based on the EQ-5D, MCS, and SRS-22 scores (p < 0.05). Patients with depression continued to experience higher NRS leg scores at 1-year follow-up (3.63 vs 2.22, p = 0.018). After controlling for covariates, the authors found that depression significantly impacted only 1-year follow-up MCS scores (β = 8.490, p < 0.05)., Conclusions: Depressed and nondepressed patients reported similar improvements after MIS surgery, except MCS scores were more likely to improve in nondepressed patients.

Background: Patient satisfaction has become an important variable in assessing outcomes after spine surgery. Although minimally invasive surgery (MIS) techniques have become popular owing to reduced perioperative complications compared with open deformity surgery, whether patient-reported postoperative satisfaction differ between the 2 surgical approaches is unclear. The aim of this study was to characterize postoperative patient-reported outcomes (PRO) in patients who underwent open surgery or MIS for adult spinal deformity (ASD)., Methods: PRO scores were prospectively collected for patients undergoing deformity correction surgery between 2016 and 2018. Inclusion criteria were age >18 years, ASD, and completed PRO surveys. Patient demographic, clinical, and radiographic data and PRO survey responses were analyzed. A post hoc analysis comparing patients who were satisfied with their outcome and those who were unsatisfied was performed., Results: Forty patients who underwent operative management of ASD (19 in the open surgery group and 21 in the MIS group) met the criteria for inclusion in this study. Patients in the MIS group reported higher mental health and self-image scores at 6 months; however, at the 12-month follow-up, both the open surgery and MIS groups reported minimal clinically important differences in back pain, leg pain, and functional status. Patient satisfaction scores did not differ based on surgical approach or intraoperative complications., Conclusions: PRO after open surgery and after MIS for ASD reflected successful outcomes with significant improvements in PRO survey scores but with subtle differences in the postoperative recovery process. The MIS group reported faster recovery with earlier improvement in self-image and mental health scores, which may stem from correction of smaller deformities. At the 12-month follow-up, postoperative satisfaction was high for the majority of patients in both groups., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: 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., Methods: 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., Results: 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)., Conclusions: 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., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Opioid requirements in the perioperative period in patients undergoing lumbar spine fusion surgery remain problematic. Although minimally invasive surgery (MIS) techniques have been developed, there still remain substantial challenges to reducing length of hospital stay (LOS) because of postoperative opioid requirements., Objective: To study the effect of implementing an enhanced recovery after surgery (ERAS) pathway in patients undergoing a 1-level MIS transforaminal lumbar interbody fusion (MIS TLIF) at our institution., Methods: We implemented an ERAS pathway in patients undergoing an elective single-level MIS TLIF for degenerative changes at a single institution. Consecutive patients were enrolled over a 20-mo period and compared with a pre-ERAS group prior to the implementation of the ERAS protocol. The primary outcome was LOS. Secondary outcomes included reduction in morphine milligram equivalent units (MME), pain scores, postoperative urinary retention (POUR), and incidence of postoperative delirium. Patients were compared using the chi-square and Welch's 2-sample t-tests., Results: A total of 299 patients were evaluated in this study: 87 in the ERAS group and 212 in the pre-ERAS group. In the ERAS group, there was a significant reduction in LOS (3.13 ± 1.53 vs 3.71 ± 2.07 d, P = .019), total admission MME (252.74 ± 317.38 vs 455.91 ± 498.78 MME, P = .001), and the number of patients with POUR (48.3% vs 65.6%, P = .008). There were no differences in pain scores., Conclusion: This is the largest ERAS MIS fusion cohort published to date evaluating a single cohort of patients in a generalizable manner. This ERAS pathway has shown a substantial decrease in LOS and opioid requirements in the immediate perioperative and postoperative period. There is further work to be done to evaluate patients undergoing other complex spine surgical interventions., (© Congress of Neurological Surgeons 2021.)

Objective: Minimally invasive surgery (MIS) can be used as an alternative or adjunct to traditional open techniques for the treatment of patients with adult spinal deformity. Recent advances in MIS techniques, including advanced anterior approaches, have increased the range of candidates for MIS deformity surgery. The minimally invasive spinal deformity surgery (MISDEF2) algorithm was created to provide an updated framework for decision-making when considering MIS techniques in correction of adult spinal deformity., Methods: A modified algorithm was developed that incorporates a patient's preoperative radiographic parameters and leads to one of 4 general plans ranging from basic to advanced MIS techniques to open deformity surgery with osteotomies. The authors surveyed 14 fellowship-trained spine surgeons experienced with spinal deformity surgery to validate the algorithm using a set of 24 cases to establish interobserver reliability. They then re-surveyed the same surgeons 2 months later with the same cases presented in a different sequence to establish intraobserver reliability. Responses were collected and analyzed. Correlation values were determined using SPSS software., Results: Over a 3-month period, 14 fellowship-trained deformity surgeons completed the surveys. Responses for MISDEF2 algorithm case review demonstrated an interobserver kappa of 0.85 for the first round of surveys and an interobserver kappa of 0.82 for the second round of surveys, consistent with substantial agreement. In at least 7 cases, there was perfect agreement between the reviewing surgeons. The mean intraobserver kappa for the 2 surveys was 0.8., Conclusions: The MISDEF2 algorithm was found to have substantial inter- and intraobserver agreement. The MISDEF2 algorithm incorporates recent advances in MIS surgery. The use of the MISDEF2 algorithm provides reliable guidance for surgeons who are considering either an MIS or an open approach for the treatment of patients with adult spinal deformity.

Background: Spinal deformity surgery is often invasive and lengthy. Staging surgery over separate operative days may reduce complications. Staging is often used in minimally invasive treatment of adult spinal deformity (ASD)., Objective: To investigate the impact of staging on complication rates between hybrid (HYB; minimally invasive interbody with open posterior screw and rod fixation) and circumferential minimally invasive surgery (cMIS; minimally invasive interbody and screw/rod placement) procedures in patients with ASD., Methods: A multicenter database of patients with ASD was reviewed. Patients who underwent staging (at least 3 levels) and 2 years of follow-up were analyzed. A total of 99 patients underwent staging: 53 cMIS and 46 HYB surgeries. Propensity matching for levels fused resulted in 19 patients in each group. Intra- and perioperative complications were assessed., Results: Three HYB but no cMIS intraoperative complications occurred. More HYB patients had perioperative complications than cMIS patients. Neurologic complications were more frequent in HYB versus cMIS. Other complications did not differ significantly. Thirty-day reoperations were higher with cMIS than HYB, but there was no difference in reoperation rate at long-term follow-up. cMIS patients had greater improvement in the Oswestry Disability Index. There was no difference in complications between staged versus unstaged cMIS surgeries., Conclusions: cMIS staged surgeries appear safer than HYB staged surgeries, and equally safe to cMIS unstaged surgeries. Perioperative complications were significantly higher for HYB staged surgeries. HYB surgeries may have better results when performed in a single setting, whereas cMIS surgeries can be performed in 1 or 2 stages depending on surgeon preference., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Minimally invasive surgery (MIS) correction for adult spinal deformity (ASD) may reduce the need the need for postoperative skilled nursing facility (SNF) or inpatient rehabilitation (IR) placement following surgery. The likelihood of requiring placement in a facility rather than home disposition may be influenced by various factors. In addition, the associations between discharge location and outcomes and complication rates have not been elucidated in these patients. In this study, we aimed to define factors predicting disposition to an SNF/IR and to elucidate the rates of complications occurring in patients sent to home versus to a facility., Methods: A retrospective review of a multicenter ASD database, which included patients who underwent surgery between 2009 and 2014. Inclusion criteria were age >18 years, MIS as part of index surgery, location of discharge, and at least 1 of the following: pelvic tilt >20°, sagittal vertical axis >5 cm, pelvic incidence-lumbar lordosis mismatch >10, or lumbar scoliosis >20°. Patients with a 2-year follow-up were included. Preoperative demographic and radiographic data, postoperative (<30 day) complications, and health-related quality of life were analyzed., Results: A total of 182 patients met our inclusion criteria, including 113 who were discharged to home and 69 who were discharged to an SNF/IR. Older patients (>50 years) were more likely to be discharged to an SNF/IR (P = 0.043). Those aged >70 years were 6-fold more likely to go to an SNF/IR. No association was identified between discharge to an SNF/IR and any radiographic parameters except preoperative pelvic tilt (odds ratio [OR], 1.11; P = 0.009). Staged cases were more likely to be discharged to an SNF/IR (OR, 3.24; 95% confidence interval, 1.11-9.46; P = 0.032); otherwise, there was no difference in levels treated, operating time, estimated blood loss, osteotomy, or length of hospital stay. Patients requiring discharge to an SNF/IR had a higher rate of complications (58% vs. 39.8%; P = 0.017), including major complications (19.5% vs. 42%; P = 0.001), perioperative complications (14.2% vs. 31.9%; P = 0.004) and infections (3.5% vs. 13%; P = 0.016). Patients discharged to an SNF/IR had a higher rate of revision (19.5% vs. 33%; P = 0.035). Health-related quality of life measures were similar regardless of disposition., Conclusions: Older patients and those undergoing staged MIS deformity correction have a higher likelihood of postoperative disposition to an SNF/IR. Complications occurred more commonly in those patients requiring transfer to an SNF/IR after hospitalization., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: The incidence of adjacent segment disease (ASD) after lumbar spine surgery is a condition that has become increasingly common as the rate of lumbar spine surgery continues to rise. Minimally invasive techniques continue to be refined and offer an opportunity to treat ASD with minimal tissue disruption, lower blood loss, a shorter hospital stay, and decreased morbidity. The aim of this report is to describe the various minimally invasive options for ASD with a comprehensive review of the existing literature., Materials and Methods: A retrospective chart review of patients undergoing minimally invasive spine surgery (MIS) for ASD of the lumbar spine was conducted. Four basic techniques and their modifications were identified to address ASD. Illustrative cases, surgical techniques, and post-surgical outcomes are described., Results: Four MIS techniques were identified as common surgical methods to correct ASD. (1) Non-instrumented discectomy, foraminotomy, or decompression, (2) anterior lumbar interbody fusion (ALIF), (3) transforaminal lumbar interbody fusion (TLIF), and (4) lateral lumbar interbody fusion (LLIF) were found to be MIS techniques that address ASD. ALIF and LLIF provide indirect decompression of the neural foramina, while TLIF provides direct decompression. The addition and removal of screws and rods can be combined with any of these techniques., Conclusions: MIS techniques provide decompression of the neural elements, stabilization, and, potentially, fusion for patients with ASD. These illustrated cases and the review of MIS surgical techniques can provide a comprehensive framework for addressing ASD., Competing Interests: There are no conflicts of interest

Background: Minimally invasive surgery (MIS) techniques used for management of adult spinal deformity (ASD) aim to decrease the physiological demand on patients and minimize postoperative complications. A circumferential MIS (cMIS) protocol offers the potential to maximize this advantage over standard open approaches, through the concurrent use of multiple MIS techniques., Objective: To demonstrate through a case example the execution of a cMIS protocol for management of an ASD patient with severe deformity., Methods: Thorough preoperative assessment, surgical planning, and medical optimization were completed. Deformity correction was performed over 2 stages. During the first stage, interbody fusion was performed via an oblique lateral approach at all levels of the lumbar spine intended to be included in the final construct. The patient was kept as an inpatient and mobilized postoperatively. They were then re-imaged with standing films. The second stage occurred after 3 d and involved percutaneous instrumentation of all levels. Posterior fusion of the thoracic levels was achieved through decortication of pars and facets. These areas were accessed through the intermuscular plane established by the percutaneous screws. The patient was mobilizing on their first postoperative day., Results: In a 66-yr-old female with severe sagittal imbalance and debilitating back pain, effective use of this cMIS protocol allowed for correction of the Cobb angle from 52° to 4° correction of spinopelvic parameters and 13 cm of sagittal vertical axis improvement. No complications were identified by 2 yr postoperative., Conclusion: As a systematization of multiple MIS techniques combined, in a specific and staged manner, this cMIS protocol could provide a safe and effective approach to the management of ASD., (Copyright © 2017 by the Congress of Neurological Surgeons)

Background: Minimally invasive transforaminal lumbar interbody fusion (TLIF) has undergone significant evolution since its conception as a fusion technique to treat lumbar spondylosis. Minimally invasive TLIF is commonly performed using intraoperative two-dimensional fluoroscopic x-rays. However, intraoperative computed tomography (CT)-based navigation during minimally invasive TLIF is gaining popularity for improvements in visualizing anatomy and reducing intraoperative radiation to surgeons and operating room staff. This is the first study to compare clinical outcomes and cost between these 2 imaging techniques during minimally invasive TILF., Methods: For comparison, 28 patients who underwent single-level minimally invasive TLIF using fluoroscopy were matched to 28 patients undergoing single-level minimally invasive TLIF using CT navigation based on race, sex, age, smoking status, payer type, and medical comorbidities (Charlson Comorbidity Index). The minimum follow-up time was 6 months. The 2 groups were compared in regard to clinical outcomes and hospital reimbursement from the payer perspective., Results: Average surgery time, anesthesia time, and hospital length of stay were similar for both groups, but average estimated blood loss was lower in the fluoroscopy group compared with the CT navigation group (154 mL vs. 262 mL; P = 0.016). Oswestry Disability Index, back visual analog scale, and leg visual analog scale scores similarly improved in both groups (P > 0.05) at 6-month follow-up. Cost analysis showed that average hospital payments were similar in the fluoroscopy versus the CT navigation groups ($32,347 vs. $32,656; P = 0.925) as well as payments for the operating room (P = 0.868)., Conclusions: Single minimally invasive TLIF performed with fluoroscopy versus CT navigation showed similar clinical outcomes and cost at 6 months., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Of Background Data: Traditional open surgical techniques for correction of adult degenerative scoliosis (ADS) are often associated with increased blood loss, postoperative pain, and complications. Minimally invasive (MIS) techniques have been utilized to address these issues; however, concerns regarding improving certain alignment parameters have been raised., Objective: A new "push-through" technique for MIS correction of ADS has been developed wherein a rod is bent before its placement into the screw heads and then contoured further to yield improved correction of radiographic parameters., Methods and Study Design: Preoperative and postoperative radiographic measurements of 3 patients who underwent MIS correction of scoliosis using the "push-through" technique were compared with 22 prior patients who had received traditional MIS correction. All patients received staged correction of scoliosis. The first stage involved insertion of lateral lumbar interbodies. Standing x-rays were then evaluated for overall global balance. The second stage involved appropriate MIS facetectomies, facet fusions, posterior transforaminal interbodies at lower lumbar segments, and finally the placement of rods.TECHNIQUE OVERVIEW:: (1) A long rod composed of titanium is bent with a mild lordosis and passed through the extensions of the screw heads cephalad to caudad. (2) The rod is passed fully through the incision so it extrudes from the caudal end of the construct. At this point, further lordosis is bent into the rods. (3) The rod is then pulled back into the appropriate position. (4) The unnecessary cephalad rod is then cut to appropriate length with a circular saw. (5) Rod reducers are then sequentially lowered and tightened to achieve the desired correction., Results: Mean age for all patients was 66.02 years. Preoperative coronal Cobb, sagittal vertical axis (SVA), and pelvic incidence (PI) were similar in all patients, whereas lumbar lordosis (LL) was smaller (15.27 vs. 29.85 degrees, P=0.00389) and pelvic tilt (PT) was larger (37.00 vs. 27.00 degrees, P=0.00011) in "push-through" patients. Postoperatively, "pushthrough" patients experienced greater correction of LL (21.93 vs. 3.70 degrees, P=0.00001), PI-LL (-18.57 vs. -0.26 degrees, P=0.00471), PT (-7.67 vs. -0.40 degrees, P=0.00341), SVA (-40.67 mm vs. 0.95 mm, P=0.05846), and coronal Cobb (-20.23 vs. -18.76 degrees, P=0.75)., Conclusions: This new method of contouring a rod enables improved LL. This technique is easy to perform and can be a valuable tool in treating ADS using MIS techniques.

Introduction: Minimally invasive surgical (MIS) techniques are gaining popularity in the treatment of adult spinal deformity (ASD). The premise is that MIS techniques will lead to equivalent outcomes and a reduction in perioperative complications when compared with open techniques. Potential issues with MIS techniques are a limited capacity to correct lumbar lordosis, unknown long-term efficacy, and the potential need for revision surgery. This study compares reoperation rates and reasons for reoperation following MIS, hybrid, and open surgery for ASD through multicenter database analysis., Methods: We retrospectively analyzed a prospective multicenter ASD database comparing open and MIS correction techniques. Inclusion criteria were: age > 18 years with minimum 20° coronal lumbar Cobb angle, a minimum of three levels fused, and minimum 2-year follow-up. Patients were propensity matched for preoperative sagittal vertebral axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), and number of levels fused. We included 189 patients from three propensity-matched subgroups of 63 patients each: (1) MIS: lateral or transforaminal lumbar interbody fusion (LIF) and percutaneous pedicle instrumentation, (2) Hybrid: MIS LIF with open posterior segmental fixation (PSF), and (3) OPEN: open posterior fixation ± osteotomies., Results: With propensity matching, there were significant differences between groups in pre-op SVA or PI-LL (p > 0.05). The MIS group had significantly fewer levels fused (5.4) (0-14) than the OPEN group (7.4) (p = 0.002) (0-17). The rate of revision surgery was significantly different between the groups with a higher rate of revision (27 %) amongst the HYB group versus MIS = 11.1 %, and OPEN = 12.0 %. The most common reason for reoperation in the OPEN and HYB groups was a postoperative neurological deficit (7.9 and 11.1 %), respectively. The most common reason for reoperation in the MIS group was pseudoarthrosis (7.9 %)., Conclusions: Reoperation rates were not statistically different among the MIS, and OPEN surgical groups, but differed significantly on multivariate analysis with HYB group. The incidence of reoperations was twice as high in the Hybrid group compared to OPEN and MIS.

OBJECTIVE Minimally invasive surgery (MIS) techniques are increasingly used to treat adult spinal deformity. However, standard minimally invasive spinal deformity techniques have a more limited ability to restore sagittal balance and match the pelvic incidence-lumbar lordosis (PI-LL) than traditional open surgery. This study sought to compare "best" versus "worst" outcomes of MIS to identify variables that may predispose patients to postoperative success. METHODS A retrospective review of minimally invasive spinal deformity surgery cases was performed to identify parameters in the 20% of patients who had the greatest improvement in Oswestry Disability Index (ODI) scores versus those in the 20% of patients who had the least improvement in ODI scores at 2 years' follow-up. RESULTS One hundred four patients met the inclusion criteria, and the top 20% of patients in terms of ODI improvement at 2 years (best group, 22 patients) were compared with the bottom 20% (worst group, 21 patients). There were no statistically significant differences in age, body mass index, pre- and postoperative Cobb angles, pelvic tilt, pelvic incidence, levels fused, operating room time, and blood loss between the best and worst groups. However, the mean preoperative ODI score was significantly higher (worse disability) at baseline in the group that had the greatest improvement in ODI score (58.2 vs 39.7, p < 0.001). There was no difference in preoperative PI-LL mismatch (12.8° best vs 19.5° worst, p = 0.298). The best group had significantly less postoperative sagittal vertical axis (SVA; 3.4 vs 6.9 cm, p = 0.043) and postoperative PI-LL mismatch (10.4° vs 19.4°, p = 0.027) than the worst group. The best group also had better postoperative visual analog scale back and leg pain scores (p = 0.001 and p = 0.046, respectively). CONCLUSIONS The authors recommend that spinal deformity surgeons using MIS techniques focus on correcting a patient's PI-LL mismatch to within 10° and restoring SVA to < 5 cm. Restoration of these parameters seems to impact which patients will attain the greatest degree of improvement in ODI outcomes, while the spines of patients who do the worst are not appropriately corrected and may be fused into a fixed sagittal plane deformity.

Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has been scrutinized for having a complex learning curve. Careful assessment of MI-TLIF complications and critical analyses of prevention may aid a safe adoption of this technique. The current report focuses on the incidence of interbody cage extrusions following MI-TLIF in a series of 513 patients. The authors discuss their experience with graft extrusions and provide methods to minimize this complication. This study retrospectively reviewed 513 prospectively followed patients who underwent MI-TLIF over a 10 year period. The inclusion criteria consisted of all patients who underwent one to three level MI-TLIF, from whom the incidence of cage extrusion was analyzed. Cage extrusion was defined as an interbody graft migrating outside the cephalad and caudal vertebral body posterior margin. Cage extrusions were diagnosed by comparing the intraoperative radiographs to the postoperative radiographs. Patients with >10° coronal curves, significant sagittal malalignment, infection, and preoperative instrumentation failure were excluded. Of 513 patients undergoing MI-TLIF, five patients (0.97%) were diagnosed with cage migrations. The mean follow-up duration was 13.6 ± standard deviation of 8.8 months. Complications included asymptomatic cage migration alone (two patients) neurological decline (two patients) and epidural hematoma (one patient). On average, cage migrations cost a university hospital an additional $US17,217 for revision treatment. While the incidence of cage migrations is low (0.97%), it can lead to postoperative complications that require revision surgery and increased hospital costs. The risk for this significant complication can be minimized with proper technique and patient selection., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

OBJECT Patients with symptomatic intradural-extramedullary (ID-EM) tumors may be successfully treated with resection of the lesion and decompression of associated neural structures. Studies of patients undergoing open resection of these tumors have reported high rates of gross-total resection (GTR) with minimal long-term neurological deficit. Case reports and small case series have suggested that these patients may be successfully treated with minimally invasive surgery (MIS). These studies have been limited by small patient populations. Moreover, there are no studies directly comparing perioperative outcomes between patients treated with open resection and MIS. The objective of this study was to compare perioperative outcomes in patients with ID-EM tumors treated using open resection or MIS. METHODS A retrospective review was performed using data collected from 45 consecutive patients treated by open resection or MIS for ID-EM spine tumors. These patients were treated over a 9-year period between April 2003 and October 2012 at Northwestern University and the University of Chicago. Statistical analysis was performed to compare perioperative outcomes between the two groups. RESULTS Of the 45 patients in the study, 27 were treated with the MIS approach and 18 were treated with the open approach. Operative time was similar between the two groups: 256.3 minutes in the MIS group versus 241.1 minutes in the open group (p = 0.55). Estimated blood loss was significantly lower in the MIS group (133.7 ml) compared with the open group (558.8 ml) (p < 0.01). A GTR was achieved in 94.4% of the open cases and 92.6% of the MIS cases (p = 0.81). The mean hospital stay was significantly shorter in the MIS group (3.9 days) compared with the open group (6.1 days) (p < 0.01). There was no significant difference between the complication rates (p = 0.32) and reoperation rates (p = 0.33) between the two groups. Multivariate analysis demonstrated an increased rate of complications in cervical spine tumors (OR 15, p = 0.05). CONCLUSIONS Thoracolumbar ID-EM tumors may be safely and effectively treated with either the open approach or an MIS approach, with an equivalent rate of GTR, perioperative complication rate, and operative time. Patients treated with an MIS approach may benefit from a decrease in operative blood loss and shorter hospital stays.

OBJECT Transforaminal lumbar interbody fusion (TLIF) has become one of the preferred procedures for circumferential fusion in the lumbar spine. Over the last decade, advances in surgical techniques have enabled surgeons to perform the TLIF procedure through a minimally invasive approach (MI-TLIF). There are a few studies reported in the medical literature in which perioperative complication rates of MI-TLIF were evaluated; here, the authors present the largest cohort series to date. They analyzed intraoperative and perioperative complications in 513 consecutive MI-TLIF-treated patients with lumbar degenerative disc disease. METHODS The authors performed a retrospective review of prospectively collected data on 513 consecutive patients treated over a 10-year period for lumbar degenerative disc disease using MI-TLIF. All patients undergoing either a first-time or revision 1- or 2-level MI-TLIF procedure were included in the study. Demographic, intraoperative, and perioperative data were collected and analyzed using bivariate analyses (Student t-test, analysis of variance, odds ratio, chi-square test) and multivariate analyses (logistic regression). RESULTS A total of 513 patients underwent an MI-TLIF procedure, and the perioperative complication rate was 15.6%. The incidence of durotomy was 5.1%, and the medical and surgical infection rates were 1.4% and 0.2%, respectively. A statistically significant increase in the infection rate was seen in revision MI-TLIF cases, and the same was found for the perioperative complication rate in multilevel MI-TLIF cases. Instrumentation failure occurred in 2.3% of the cases. After analysis, no statistically significant difference was seen in the rates of durotomy during revision and multilevel surgeries. There was no significant difference between the complication rates when stratified according to presenting diagnosis. CONCLUSIONS To the authors' knowledge, this is the largest study of perioperative complications in MI-TLIF in the literature. A total of 513 patients underwent MI-TLIF (perioperative complication rate 15.6%). The most common complication was a durotomy (5.1%), and there was only 1 surgical wound infection (0.2%). There were significantly more perioperative infections in revision MI-TLIF cases and more perioperative complications in multilevel MI-TLIF cases. The results of this study suggest that MI-TLIF has a similar or better perioperative complication profile than those documented in the literature for open-TLIF treatment of degenerative lumbar spine disease.

Object: Minimally invasive surgery (MIS) techniques are becoming a more common means of treating adult spinal deformity (ASD). The aim of this study was to compare the hybrid (HYB) surgical approach, involving minimally invasive lateral interbody fusion with open posterior instrumented fusion, to the circumferential MIS (cMIS) approach to treat ASD., Methods: The authors performed a retrospective, multicenter study utilizing data collected in 105 patients with ASD who were treated via MIS techniques. Criteria for inclusion were age older than 45 years, coronal Cobb angle greater than 20°, and a minimum of 1 year of follow-up. Patients were stratified into 2 groups: HYB (n = 62) and cMIS (n = 43)., Results: The mean age was 60.7 years in the HYB group and 61.0 years in the cMIS group (p = 0.910). A mean of 3.6 interbody fusions were performed in the HYB group compared with a mean of 4.0 interbody fusions in the cMIS group (p = 0.086). Posterior fusion involved a mean of 6.9 levels in the HYB group and a mean of 5.1 levels in the cMIS group (p = 0.003). The mean follow-up was 31.3 months for the HYB group and 38.3 months for the cMIS group. The mean Oswestry Disability Index (ODI) score improved by 30.6 and 25.7, and the mean visual analog scale (VAS) scores for back/leg pain improved by 2.4/2.5 and 3.8/4.2 for the HYB and cMIS groups, respectively. There was no significant difference between groups with regard to ODI or VAS scores. For the HYB group, the lumbar coronal Cobb angle decreased by 13.5°, lumbar lordosis (LL) increased by 8.2°, sagittal vertical axis (SVA) decreased by 2.2 mm, and LL-pelvic incidence (LL-PI) mismatch decreased by 8.6°. For the cMIS group, the lumbar coronal Cobb angle decreased by 10.3°, LL improved by 3.0°, SVA increased by 2.1 mm, and LL-PI decreased by 2.2°. There were no significant differences in these radiographic parameters between groups. The complication rate, however, was higher in the HYB group (55%) than in the cMIS group (33%) (p = 0.024)., Conclusions: Both HYB and cMIS approaches resulted in clinical improvement, as evidenced by decreased ODI and VAS pain scores. While there was no significant difference in degree of radiographic correction between groups, the HYB group had greater absolute improvement in degree of lumbar coronal Cobb angle correction, increased LL, decreased SVA, and decreased LL-PI. The complication rate, however, was higher with the HYB approach than with the cMIS approach.

Background Context: Posterior cervical foraminotomy (PCF) with or without microdiscectomy (posterior cervical discectomy [PCD]) is a frequently used surgical technique for cervical radiculopathy secondary to foraminal stenosis or a laterally located herniated disc. Currently, these procedures are being performed with increasing frequency using advanced minimally invasive techniques. Although the safety and efficacy of minimally invasive PCF/PCD (MI-PCF/PCD) have been established, reports on long-term outcome and need for secondary surgical intervention at the index or adjacent level are lacking., Purpose: To determine the rates of complications, long-term outcomes, and need for secondary surgical intervention at the index or adjacent level after MI-PCF and microdiscectomy., Study Design: Retrospective analysis of a prospective cohort., Patient Sample: Seventy patients treated with MI-PCF and/or MI-PCD for cervical radiculopathy., Outcome Measures: Visual Analog Scale for neck/arm (VASN/A) pain and Neck Disability Index (NDI)., Methods: Ninety-seven patients underwent MI-PCF with or without MI-PCD between 2002 and 2011. Adequate prospective follow-up was available for 70 patients (95 cervical levels). The primary outcome assessed was need for secondary surgical intervention at the index or adjacent level. The secondary outcomes assessed included complications and improvements in NDI and VASN/A scores. All complications were reviewed. Mixed-model analyses of variance with random subject effects and autoregressive first-order correlation structures were used to test for differences among NDI, VASA, and VASN measurements made over time while accounting for the correlation among repeated observations within a patient. All statistical hypothesis tests were conducted at the 5% level of significance., Results: Patients were followed for a mean of 32.1 months. Of 70 patients operated, there were 3 (4.3%) complications (1 cerebrospinal fluid leak, 1 postoperative wound hematoma, and 1 radiculitis), none of which required a secondary operative intervention. Five patients required an anterior cervical discectomy and fusion (eight total levels fused) on average 44.4 months after the index surgery. Of those, five (5.3%) were at the index level and three (2.1%) were at adjacent levels. Neck Disability Index scores improved significantly (p<.0001) immediately postoperatively and continued to decrease gradually with time. Visual Analog Scale for neck/arm scores improved significantly (p<.0001) from baseline immediately postoperatively but tended to plateau with time., Conclusions: Minimally invasive PCF with or without MI-PCD is an excellent alternative for cervical radiculopathy secondary to foraminal stenosis or a laterally located herniated disc. There is a low rate (1.1% per index level per year) of future index site fusion and a very low rate (0.9% per adjacent level per year) of adjacent-level disease requiring surgery., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Object: Various surgical approaches, including open, minimally invasive, and hybrid techniques, have gained momentum in the management of adult spinal deformity. However, few data exist on the radiographic outcomes of different surgical techniques. The objective of this study was to compare the radiographic and clinical outcomes of the surgical techniques used in the treatment of adult spinal deformity., Methods: The authors conducted a retrospective review of two adult spinal deformity patient databases, a prospective open surgery database and a retrospective minimally invasive surgery (MIS) and hybrid surgery database. The time frame of enrollment in this study was from 2007 to 2012. Spinal deformity patients were stratified into 3 surgery groups: MIS, hybrid surgery, and open surgery. The following pre- and postoperative radiographic parameters were assessed: lumbar major Cobb angle, lumbar lordosis, pelvic incidence minus lumbar lordosis (PI-LL), sagittal vertical axis, and pelvic tilt. Scores on the Oswestry Disability Index (ODI) and a visual analog scale (VAS) for both back and leg pain were also obtained from each patient., Results: Of the 234 patients with adult spinal deformity, 184 patients had pre- and postoperative radiographs and were thus included in the study (MIS, n = 42; hybrid, n = 33; open, n = 109). Patients were a mean of 61.7 years old and had a mean body mass index of 26.9 kg/m(2). Regarding radiographic outcomes, the MIS group maintained a significantly smaller mean lumbar Cobb angle (13.1°) after surgery compared with the open group (20.4°, p = 0.002), while the hybrid group had a significantly larger lumbar curve correction (26.6°) compared with the MIS group (18.8°, p = 0.045). The mean change in the PI-LL was larger for the hybrid group (20.6°) compared with the open (10.2°, p = 0.023) and MIS groups (5.5°, p = 0.003). The mean sagittal vertical axis correction was greater for the open group (25 mm) compared with the MIS group (≤ 1 mm, p = 0.008). Patients in the open group had a significantly larger postoperative thoracic kyphosis (41.45°) compared with the MIS patients (33.5°, p = 0.005). There were no significant differences between groups in terms of pre- and postoperative mean ODI and VAS scores at the 1-year follow-up. However, patients in the MIS group had much lower estimated blood loss and transfusion rates compared with patients in the hybrid or open groups (p < 0.001). Operating room time was significantly longer with the hybrid group compared with the MIS and open groups (p < 0.001). Major complications occurred in 14% of patients in the MIS group, 14% in the hybrid group, and 45% in the open group (p = 0.032)., Conclusions: This study provides valuable baseline characteristics of radiographic parameters among 3 different surgical techniques used in the treatment of adult spinal deformity. Each technique has advantages, but much like any surgical technique, the positive and negative elements must be considered when tailoring a treatment to a patient. Minimally invasive surgical techniques can result in clinical outcomes at 1 year comparable to those obtained from hybrid and open surgical techniques.

Object: It is hypothesized that minimally invasive surgical techniques lead to fewer complications than open surgery for adult spinal deformity (ASD). The goal of this study was to analyze matched patient cohorts in an attempt to isolate the impact of approach on adverse events., Methods: Two multicenter databases queried for patients with ASD treated via surgery and at least 1 year of follow-up revealed 280 patients who had undergone minimally invasive surgery (MIS) or a hybrid procedure (HYB; n = 85) or open surgery (OPEN; n = 195). These patients were divided into 3 separate groups based on the approach performed and were propensity matched for age, preoperative sagittal vertebral axis (SVA), number of levels fused posteriorly, and lumbar coronal Cobb angle (CCA) in an attempt to neutralize these patient variables and to make conclusions based on approach only. Inclusion criteria for both databases were similar, and inclusion criteria specific to this study consisted of an age > 45 years, CCA > 20°, 3 or more levels of fusion, and minimum of 1 year of follow-up. Patients in the OPEN group with a thoracic CCA > 75° were excluded to further ensure a more homogeneous patient population., Results: In all, 60 matched patients were available for analysis (MIS = 20, HYB = 20, OPEN = 20). Blood loss was less in the MIS group than in the HYB and OPEN groups, but a significant difference was only found between the MIS and the OPEN group (669 vs 2322 ml, p = 0.001). The MIS and HYB groups had more fused interbody levels (4.5 and 4.1, respectively) than the OPEN group (1.6, p < 0.001). The OPEN group had less operative time than either the MIS or HYB group, but it was only statistically different from the HYB group (367 vs 665 minutes, p < 0.001). There was no significant difference in the duration of hospital stay among the groups. In patients with complete data, the overall complication rate was 45.5% (25 of 55). There was no significant difference in the total complication rate among the MIS, HYB, and OPEN groups (30%, 47%, and 63%, respectively; p = 0.147). No intraoperative complications were reported for the MIS group, 5.3% for the HYB group, and 25% for the OPEN group (p < 0.03). At least one postoperative complication occurred in 30%, 47%, and 50% (p = 0.40) of the MIS, HYB, and OPEN groups, respectively. One major complication occurred in 30%, 47%, and 63% (p = 0.147) of the MIS, HYB, and OPEN groups, respectively. All patients had significant improvement in both the Oswestry Disability Index (ODI) and visual analog scale scores after surgery (p < 0.001), although the MIS group did not have significant improvement in leg pain. The occurrence of complications had no impact on the ODI., Conclusions: Results in this study suggest that the surgical approach may impact complications. The MIS group had significantly fewer intraoperative complications than did either the HYB or OPEN groups. If the goals of ASD surgery can be achieved, consideration should be given to less invasive techniques.

Object: Minimally invasive surgery (MIS) is an alternative to open deformity surgery for the treatment of patients with adult spinal deformity. However, at this time MIS techniques are not as versatile as open deformity techniques, and MIS techniques have been reported to result in suboptimal sagittal plane correction or pseudarthrosis when used for severe deformities. The minimally invasive spinal deformity surgery (MISDEF) algorithm was created to provide a framework for rational decision making for surgeons who are considering MIS versus open spine surgery., Methods: A team of experienced spinal deformity surgeons developed the MISDEF algorithm that incorporates a patient's preoperative radiographic parameters and leads to one of 3 general plans ranging from MIS direct or indirect decompression to open deformity surgery with osteotomies. The authors surveyed fellowship-trained spine surgeons experienced with spinal deformity surgery to validate the algorithm using a set of 20 cases to establish interobserver reliability. They then resurveyed the same surgeons 2 months later with the same cases presented in a different sequence to establish intraobserver reliability. Responses were collected and tabulated. Fleiss' analysis was performed using MATLAB software., Results: Over a 3-month period, 11 surgeons completed the surveys. Responses for MISDEF algorithm case review demonstrated an interobserver kappa of 0.58 for the first round of surveys and an interobserver kappa of 0.69 for the second round of surveys, consistent with substantial agreement. In at least 10 cases there was perfect agreement between the reviewing surgeons. The mean intraobserver kappa for the 2 surveys was 0.86 ± 0.15 (± SD) and ranged from 0.62 to 1., Conclusions: The use of the MISDEF algorithm provides consistent and straightforward guidance for surgeons who are considering either an MIS or an open approach for the treatment of patients with adult spinal deformity. The MISDEF algorithm was found to have substantial inter- and intraobserver agreement. Although further studies are needed, the application of this algorithm could provide a platform for surgeons to achieve the desired goals of surgery.

The lateral transpsoas approach for interbody fusion is a minimally invasive technique that has been gaining increasing popularity in the management of a variety of spinal degenerative disorders. Recently, there has been increasing utilization of this technique in the management of adult deformity. The authors present a review of the current evidence of using the lateral lumbar transpsoas approach in the correction of adult degenerative scoliosis., (Copyright © 2014 Elsevier Inc. All rights reserved.)

In the past, treatment of thoracic disc herniations has not been seen as a minimally invasive procedure. This article evaluates the progression of minimally invasive techniques for the treatment of thoracic disc herniations. Discussion of the advantages and disadvantages of the approaches is noted so that surgeons may consider them while incorporating these techniques in their practice., (Copyright © 2014 Elsevier Inc. All rights reserved.)

We describe our experience using a minimal access approach for multi-level dorsal decompression of the thoracic spine that may limit approach-related soft-tissue injury and spinal destabilization. Additionally, three patients, each with unique compressive thoracic pathology, are discussed. A single minimal access technique, using multi-level hemilaminotomies, was used to address these unique pathologies via a similar approach. The three patients in this study had a mean age of 49.3 years (range: 45-55 years), mean estimated blood loss of 750 cc (range: 350-1000 cc), mean operative time of 3.8 hours (range: 3-5 hours), and a mean post-operative hospital stay of 2.3 days (range: 2-3 days). Complete decompression was achieved with resolution of symptoms in all patients. Long-term follow-up averaged 26.7 months (range: 15-36 months). Radiographic decompression was demonstrated in all patients. Minimal access techniques using muscle-splitting tubular retractor systems can effectively treat multi-level dorsal compression of the thoracic cord, while potentially limiting morbidity and long-term spinal instability., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Objective: Minimally invasive spine surgery (MISS) techniques have similar long-term outcomes compared to open surgery for patients undergoing 1- or 2-level discectomy, foraminotomy, or laminectomy. However, the rate of cerebrospinal fluid (CSF) leaks with both techniques has not been well established in the literature. This study sought to compare the rate and clinical impact of CSF leak in open lumbar foraminotomy, discectomy, or laminectomy with comparable MISS approaches., Methods: A total of 863 patients undergoing 1- or 2-level discectomy, foraminotomy, or laminectomy by either MISS an open technique were evaluated for CSF leaks. Variables assessed included operative time, blood loss, CSF leaks, hospital stay, days with lumbar drain, days of postoperative flat bed rest, and postoperative intervention. Statistical analyses include univariate analysis (Student t test, analysis of variance, odds ratio, χ(2)) and bivariate analysis (logistic regression)., Results: In the MISS group there were 15 CSF leaks (4.7%), and 49 CSF leaks (9.0%) in the open group. Eight patients in the open group required lumbar drainage, compared to zero patients in the MISS group. Twelve patients required reoperation for persistent CSF leak in the open group, compared to zero patients in the MISS group. Patients undergoing open spine surgery were 2 times more likely to have a CSF leak (odds ratio = 2.3, 95% confidence interval = 1.2 to 3.7, P = .01). Patients undergoing MISS had significantly lower reoperation rates for CSF leak repairs (open = 25% of open CSF leak cases, MISS = 0%, P < .01)., Conclusions: In this study, there was a statistically significant decreased rate of CSF leak between an MISS approach and an open surgical approach. Furthermore, CSF leaks in open surgery have a higher probability of requiring lumbar drainage or reoperation to repair the durotomy., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: The anatomic and biomechanical aspects of the L5-S1 level present unique operative challenges compared with the L4-L5 level. However, it has not been determined if self-reported outcomes and complications are different between patients treated with a minimally invasive transforaminal lumbar interbody fusion at these specific levels., Methods: There were 36 consecutive patients identified who were treated with a minimally invasive transforaminal lumbar interbody fusion procedure. Surgical indications included spondylolisthesis (grade 1 or 2) and degenerative disk disease with associated clinical symptoms. Patients completed a visual analog scale (VAS) for their back and leg and Oswestry Disability Index preoperatively and postoperatively. Outcomes were compared between patients with L4-L5 involvement and patients with L5-S1 involvement. In all patients, fusion was evaluated by dynamic view flexion and extension views at 1 year. In all patients with indeterminate results or incomplete imaging, computed tomography was performed to evaluate for bridging bone and stable hardware positioning., Results: The surgical indications between the 2 groups were similar (χ(2) = 0.089, df = 2, P = 0.956). There was no significant difference in mean operating time, intraoperative blood loss, and hospital stay (P = 0.937, 0.627, and 0.587). There was no significant difference in the long-term postoperative questionnaire results (P = 0.819 for VAS [back], 0.626 for VAS [leg], and 0.962 for Oswestry Disability Index) or the mean preoperative to postoperative change in Cobb angle (P = 0.626) between the 2 groups. Two complications, one in each group, were a rash from an antibiotic and postoperative nausea., Conclusions: Despite differences in biomechanics and unique anatomic challenges at the L5-S1 interspace, there is no difference in self-reported outcomes for patients treated with minimally invasive transforaminal lumbar interbody fusion at the L4-L5 level compared with the L5-S1 level., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: To present operative details and clinical follow-up of a series of patients with thoracic disk herniation treated with the minimally invasive technique of thoracic microendoscopic diskectomy (TMED)., Methods: TMED was performed in 16 consecutive patients (age range, 18-79 years old) with 18 thoracic disk herniations. One patient with a calcified herniation in a direct ventral location was not included in this series. Patients were positioned prone, and a tubular retractor system was placed through a muscle dilating approach. The procedure was performed with endoscopic visualization. Outcomes were assessed using modified McNab criteria., Results: There were no complications, and no case required conversion to an open procedure. The mean operative time was 153 minutes per level, and mean blood loss was 69 mL per level. Mean hospital stay was 21 hours. At a mean follow-up of 24 months (median, 22 months), 13 patients (81%) had excellent or good outcomes, 1 patient (6%) had a fair outcome, and 2 patients (13%) had poor outcomes. The two patients with poor outcomes had neurologic diagnoses (multiple sclerosis and multiple systems atrophy) that were ultimately found to be responsible for their symptoms and deficits., Conclusions: TMED is a safe and effective minimally invasive posterolateral approach for the treatment of thoracic disk herniations that lacks the morbidity associated with traditional approaches., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Minimally invasive spine surgery (MISS) techniques were developed to address morbidities associated with open spinal surgery approaches. MISS was initially applied for indications such as the microendoscopic decompression of stenosis (MEDS)-an operation that has become widely implemented in modern spine surgery practice. Minimally invasive surgery for MEDS is an excellent example of how an MISS technique has improved outcomes compared with the use of traditional open surgical procedures. In parallel with reports of surgeon experience, accumulating clinical evidence suggests that MISS is favoured over open surgery, and one could argue that the role of MISS techniques will continue to expand. As the field of minimally invasive surgery has developed, MISS has been implemented for the treatment of increasingly difficult and complex pathologies, including trauma, spinal malignancies and spinal deformity in adults. In this Review, we present the accumulating evidence in support of minimally invasive techniques for established MISS indications, such as lumbar stenosis, and discuss the need for additional level I and level II data to demonstrate the benefit of MISS over traditional open surgery. The expanding utility of MISS techniques to address an increasingly broad range of spinal pathologies is also highlighted.

As the population ages, more elderly patients will develop painful degenerative lumbar pathology requiring lumbar fusion for treatment. Unfortunately, traditional techniques for lumbar fusion have been associated with increased morbidity and mortality in elderly patients. Minimally invasive transforaminal lumbar interbody fusion (TLIF) has been associated with fewer complications; however, little specific to the elderly population has been published. Thus, we performed a retrospective analysis on 84 consecutive patients (<65 years, young--45 patients; ≥ 65 years, elderly--39 patients) who underwent single-level, minimally invasive TLIF between October 2007 and December 2010. Hospital records, including operative notes, progress notes, and discharge summaries, were reviewed for patient demographics, procedures, disposition, and perioperative and postoperative complications. There was no significant difference between the young and elderly patients with respect to the total number of major, minor, or major and minor complications. Likewise, there was no significant difference between the two groups with respect to the number of patients experiencing one or more major, minor, or major and minor complications. The overall rate of experiencing at least one perioperative or postoperative complication was 16.33% for young patients and 20.00% in the elderly cohort (p = 0.7748). Thus, elderly patients with single-level degenerative lumbar pathology requiring fusion are not at increased risk of perioperative and postoperative complications compared to younger patients when undergoing single-level, minimally invasive TLIF., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Minimally invasive modalities have demonstrated efficacy in the treatment of neurogenic claudication. Direct comparisons, however, between complication rates of these newer techniques with open surgical techniques for lumbar decompression are lacking. This single-institution study examined neurogenic claudicants between August 2007 and June 2009. A total of 26 patients received open surgical decompression, and 23 patients microendoscopic decompression. Baseline demographic characteristics, peri-operative morbidity and mortality, length of hospital stay, and final disposition following hospitalization were recorded. Morbidity was divided into major and minor categories as defined by degree of requisite intervention and adverse impact on hospital stay. Average age, number of surgical levels, and pre-operative American Society of Anesthesiologists Physical Status Index scores were similar in each group (p>0.05). While minimally invasive surgery may be associated with slightly longer operative times, there is decreased blood loss, shorter hospital stays, and likely decreased requirements for ancillary support services upon discharge., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Object: Recently, the minimally invasive, lateral retroperitoneal, transpsoas approach to the thoracolumbar spinal column has been described by various authors. This is known as the minimally invasive lateral lumbar interbody fusion. The purpose of this study is to elucidate the approach-related morbidity associated with the minimally invasive transpsoas approach to the lumbar spine. To date, there have been only a couple of reports regarding the morbidity of the transpsoas muscle approach., Methods: A nonrandomized, prospective study utilizing a self-reported patient questionnaire was conducted between January 2006 and June 2008 at Northwestern University. Data were collected in 53 patients with a follow-up period ranging from 6 months to 3.5 years. Only 2 patients were lost to follow-up., Results: Thirty-six percent (19 of 53) of patients reported subjective hip flexor weakness, 25% (13 of 53) anterior thigh numbness, and 23% (12 of 53) anterior thigh pain. However, 84% of the 19 patients reported complete resolution of their subjective hip flexor weakness by 6 months, and most experienced improved strength by 8 weeks. Of those reporting anterior thigh numbness and pain, 69% and 75% improved to their baseline function by the 6-month follow-up evaluations, respectively. All patients with self-reported subjective hip flexor weakness underwent examinations during subsequent clinic visits after surgery; however, these examinations did not confirm a motor deficit less than Grade 5. Subset analysis showed that the L3-4 and L4-5 levels were most often affected., Conclusions: The minimally invasive, transpsoas muscle approach to the lumbar spine has a number of advantages. The data show that a percentage of the patients undergoing the transpsoas approach will have temporary sensory and motor symptoms related to this approach. The majority of the symptoms are thought to be related to psoas muscle inflammation and/or stretch injury to the genitofemoral nerve due to the surgical corridor traversed during the operation. No major injuries to the lumbar plexus were encountered. It is important to educate patients prior to surgery of the possibility of these largely transient symptoms.

Cauda equina syndrome (CES) is a condition associated with significant morbidity that requires definitive surgical decompression of the nerve roots to prevent permanent disability. Traditionally, wide open decompression has been advocated to obtain optimal decompression with minimal complications. Some have been reluctant to employ minimally invasive strategies to treat urgent conditions. The authors present a small series of four patients who presented with CES and were treated with minimally invasive discectomy (MID). Operative length times (mean±standard deviation, 102.8±30.9 minutes) were comparable to reported operative length for open laminectomies. All patients had either stabilization or resolution of symptoms at the 6-week follow-up examination. No patients suffered a cerebrospinal fluid (CSF) leak post-operatively. This series of patients presenting with CED at a single institution treated with MID demonstrates that MID can be used to successfully treat CES. Even large fragments can be safely removed without increased risk of a CSF leak., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

We aim to describe the minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) technique. The MI-TLIF procedure was developed to achieve the same goal of neural decompression and interbody arthrodesis as the traditional, open TLIF techniques. MI-TLIF has been utilized in the treatment of an array of lumbar pathologies, while offering the advantages of reducing soft tissue trauma, decreasing postoperative pain, and reducing the rate of complication when compared to the open techniques. The surgical technique of MI-TLIF is described in a step-by-step fassion. A technical review of this novel minimally invasive procedure was performed. Additionally, data collected through our experience with this procedure is reported. Data was collected retrospectively from patients between January 2008 and December 2009 who underwent MI-TLIF. The mean preoperative VAS score was 6.12±2.02 compared to 2.11±2.69 postoperatively. The mean ODI score dropped from 38.29±13.19 preoperatively to 16.00 ±16.598 postoperatively. Eighty-four patients who underwent MI-TLIF between October 2007 and December 2010 were divided based on age (over or under 65 years) and intraoperative estimated blood loss (EBL) was compared. The mean EBL for the young age group was 93.37±102.16 mL compared to 100 ±61.24 mL for the older group. Operation times for the MI-TLIF procedure has decreased from 3-4 hours to approximately 2 hours throughout our experience with this technique. The MI-TLIF technique is a safe and effective procedure offering the advantages of less tissue damage, less blood loss, and reduced postoperative hospitalization over the open techniques.

Background: Far lateral lumbar disc herniations, while infrequent, are a substantial cause of morbidity causing painful radicular syndromes often accompanied by a motor or sensory deficit. Surgical treatment can be challenging technically because of unfamiliar lateral anatomy and the importance of adjacent osseous structures, notably the pars interarticularis and facet joint., Method: The traditional approach for a far lateral lumbar disc herniation involves a midline incision, wide lateral subperiosteal exposure and partial removal of these structures with the potential for iatrogenic instability. A paramedian approach to the lateral compartment of the disc space is advantageous because it directly targets the pathology. The use of recently developed minimally invasive retractor systems decreases tissue dissection and blood loss and improves postoperative recovery., Results and Discussion: We present a series of 20 patients who underwent far lateral discectomy using a minimally invasive muscle splitting approach., (© Georg Thieme Verlag KG Stuttgart · New York.)

Study Design: A cadaver study comparing 3 different minimally invasive approaches to the anterior thoracic spine., Objective: To assess the feasibility of minimally invasive thoracic corpectomy from a posterolateral approach and to compare surgical results from 3 approaches., Summary of Background Data: Traditional posterolateral approaches to the thoracic spine are effective but are associated with a high rate of operative morbidity., Methods: Thoracic corpectomies were performed using a modified tubular retractor starting at 3, 6, and 9 cm off of midline. Postoperative computed tomography scans were performed and analyzed to assess the extent of corpectomy and ventral decompression., Results: From 3 to 6 to 9 cm, a significant difference in extent of corpectomy (65.8%, 81.5%, and 82.6%, P=0.02) and ventral decompression (83.6%, 90.4%, 94.6%, P=0.05) was noted between 3 cm and the more lateral approaches. The 9 cm approach required more rib resection and average working distances of 8.4 to 11.3 cm, which made the procedure more difficult technically and less suited to the length of standard instruments., Conclusions: Minimally invasive thoracic corpectomy is feasible and a 6 cm approach off of midline appears optimal.

Object: Postoperative surgical site infections (SSIs) have been reported after 2-6% of spinal surgeries in most large series. The incidence of SSI can be < 1% after decompressive procedures and > 10% after instrumented fusions. Anecdotal evidence has suggested that there is a lower rate of SSI when minimally invasive techniques are used., Methods: A retrospective review of prospectively collected databases of consecutive patients who underwent minimally invasive spinal surgery was performed. Minimally invasive spinal surgery was defined as any spinal procedure performed through a tubular retractor system. All surgeries were performed under standard sterile conditions with preoperative antibiotic prophylaxis. The databases were reviewed for any infectious complications. Cases of SSI were identified and reviewed for clinically relevant details. The incidence of postoperative SSIs was then calculated for the entire cohort as well as for subgroups based on the type of procedure performed, and then compared with an analogous series selected from an extensive literature review., Results: The authors performed 1338 minimally invasive spinal surgeries in 1274 patients of average age 55.5 years. The primary diagnosis was degenerative in nature in 93% of cases. A single minimally invasive spinal surgery procedure was undertaken in 1213 patients, 2 procedures in 58, and 3 procedures in 3 patients. The region of surgery was lumbar in 85%, cervical in 12%, and thoracic in 3%. Simple decompressive procedures comprised 78%, instrumented arthrodeses 20%, and minimally invasive intradural procedures 2% of the collected cases. Three postoperative SSIs were detected, 2 were superficial and 1 deep. The procedural rate of SSI for simple decompression was 0.10%, and for minimally invasive fusion/fixation was 0.74%. The total SSI rate for the entire group was only 0.22%., Conclusions: Minimally invasive spinal surgery techniques may reduce postoperative wound infections as much as 10-fold compared with other large, modern series of open spinal surgery published in the literature.

Objective: To demonstrate the feasibility of and initial clinical experience with a novel minimally invasive posterolateral thoracic corpectomy technique., Methods: Seven procedures were performed on 6 cadavers to determine the feasibility of thoracic corpectomy using a minimally invasive approach. The posterolateral thoracic corpectomies were performed with expandable 22 mm diameter tubular retractor paramedian incisions. The posterolateral aspects of the vertebral bodies were accessed extrapleurally, and complete corpectomies were performed. Intraprocedural fluoroscopy and postoperative computed tomography were used to assess the degree of decompression. In addition, 2 clinical cases of T6 burst fracture, 1 T4-T5 plasmacytoma, and 1 T12 colon cancer metastasis were treated using this minimally invasive approach., Results: In the cadaveric study, an average of 93% of the ventral canal and 80% of the corresponding vertebral body were removed. The pleura and intrathoracic contents were not violated. Adequate exposure was obtained to allow interbody grafting between the adjacent vertebral bodies. The procedures were successfully performed in the 4 clinical cases using a minimally invasive technique, and the patients demonstrated good outcomes., Conclusion: Based on this study, minimally invasive posterolateral thoracic corpectomy safely and successfully allows complete spinal canal decompression without the tissue disruption associated with open thoracotomy. This approach may improve the complication rates that accompany open or even thoracoscopic approaches for thoracic corpectomy and may even allow surgical intervention in patients with significant comorbidities.

Background: Minimally invasive approaches to intradural pathology have evolved in part in an effort to reduce approach related destabilization of the spine. No biomechanical data exist however evaluating the effects of traditional and minimally invasive exposures., Methods: A finite element model of the lumbar spine was generated, and a simulated open laminectomy and a modified hemilaminectomy at L4 were performed. Forces were applied to assess changes in flexion, extension, axial rotation, and lateral bending., Findings: Open laminectomy produced much greater changes in extension, flexion, and axial rotation than the modified hemilaminectomy from the intact. Lateral bending was similarly unaffected for both exposures., Interpretation: The results suggest that a minimally invasive hemilaminar exposure preserves the structural integrity of the lumbar spine and minimizes alterations to segmental motion postoperatively.

Study Design: A validated finite element model of the intact lumbar spine (L1-S1) was modified to study the biomechanical changes as a result of surgical alteration for treatment of stenosis at L3-L4 and L4-L5 using 2 established techniques and 1 new minimally invasive technique., Objective: To investigate the impact of graded posterior element removal associated with new surgical techniques on postoperative segmental motion and loading in the annulus., Summary of Background Data: Several studies have shown that laminectomy increases and produces segmental instability unless fusion is performed. However, no data exist comparing the biomechanical impact of completely preserving the contralateral anatomy and what effect this has compared to traditional approaches., Methods: The effect of graded removal of posterior elements because of iatrogenic change associated with the 3 approaches was investigated using an 800 N compressive preload using the follower load technique and application of 8 Nm flexion, 6 Nm extension, 4 Nm torsion, and 6 Nm lateral bending moments., Results: This study shows that removal of posterior elements for treatment of stenosis at L3-L4 and L4-L5 results in increased flexion-extension and axial rotation at the surgical site. This study also shows that the segmental motion following a traditional laminectomy is greater than the minimally invasive approach in flexion, extension, left and right axial rotation. Moderate preservation of the posterior elements which occurs in the intralaminar approach generates greater segmental motion that the minimally invasive approach in extension, left and right axial rotation., Conclusion: Minimization of bone and ligament removal associated with minimally invasive procedures results in greater preservation of the normal motion of the lumbar spine after surgery. This study suggests that preservation of the posterior spinal elements associated with minimally invasive surgery could minimize the risk of developing de novo postoperative changes in spinal alignment and/or acceleration of facet and disc degeneration.

Objective: Many patients undergoing lumbar spine fusion are overweight or obese. The relationship between body habitus and outcome after lumbar spine fusion surgery is not well defined., Methods: We analyzed a prospectively maintained database of self-reported pain and quality of life measures, including Visual Analog Scale pain score, Short Form 36, and Oswestry Disability Index. We selected patients undergoing minimally invasive transforaminal lumbar interbody fusion between September 2002 and June 2006 at a single institution. We used linear regression models and mixed-effects linear models to examine the relationships between body habitus and self-reported outcomes., Results: The analysis identified 110 patients meeting the study criteria, with a median follow-up period of 14.8 months. The mean age was 56 years, mean height was 169 cm, and mean weight was 82.2 kg. The mean body mass index (BMI) was 28.7 kg/m2; 31% of patients were overweight (BMI, 25-29.9), and 32% of patients were obese (BMI, >30). Linear regression analysis did not identify a correlation between weight or BMI and pre- and postsurgery changes in any of the outcome measures. The significant findings observed in the mixed-effects linear models were that the changing patterns of Short Form 36 Body Pain subscale and Short Form 36 Vitality subscale varied significantly by category of BMI (P = 0.01 and P = 0.002, respectively), but not significantly if continuous BMI was used (P = 0.53 and P = 0.46, respectively). BMI correlated marginally with estimated blood loss (P = 0.08), but not operative time, length of hospital stay, or complications., Conclusion: Among this cohort of minimally invasive lumbar fusion patients, body habitus measured by BMI, weight, or height did not have a significant relationship with most self-reported outcome measures, operative time, length of hospital stay, or complications. Obesity should not be considered a contraindication to minimally invasive lumbar spinal fusion surgery.

Objective: Surgery for thoracolumbar deformity can lead to significant muscle injury, excessive blood loss, and severe postoperative pain. The aim of the following studies was to determine the feasibility of minimally invasive posterior thoracic corpectomy and thoracolumbar osteotomy techniques for deformity in human cadavers and select clinical cases., Methods: Human cadaveric specimens were procured for thoracic corpectomy and Smith-Petersen and pedicle subtraction osteotomy using a minimally invasive approach. Post-procedural computed tomography was used to assess the degree of decompression following corpectomy and the extent of bone resection after osteotomy. Pre and post-osteotomy closure Cobb angles were measured to evaluate the degree of correction achieved., Results: The minimally invasive lateral extracavitary approach for thoracic corpectomy provided adequate exposure and allowed excellent spinal canal decompression while minimizing tissue disruption. Nearly complete osteotomies of both types could be achieved through a tubular retractor with a modest change in Cobb angle., Conclusion: These techniques may play a role in deformity surgery for select cases with further technological advancements.