Search

Previous studies have shown the potential for intervertebral disc tissue regeneration is very limited. While in vivo and in vitro studies have shown that traction can restore disc height and internal pressure, in many clinical studies it was shown that axial mechanical traction for the treatment of low back pain is ineffective.The aim of this study was to identify how the disc could be distracted, how to define the state of traction, and to further examine the feasibility of regenerating or restoring the degenerative disc by means of traction.A macro- and microlevel structural analysis of degenerative discs of rat tail before and after controlled immobilization-traction.In this study, 49 6-month-old male Sprague-Dawley rats were randomly assigned to one of seven groups. Group A was the sham control group in which caudal vertebrae were instrumented with K-wires only. In Group B (model group), caudal vertebrae were immobilized using a custom-made external device to fix four caudal vertebrae (Co7-Co10) and Co8-Co9 underwent 4 weeks of compression to induce moderate disc degeneration. In Group C, vertebrae Co8-Co9 underwent 4 weeks of compression to induce moderate disc degeneration, followed by removal of the external apparatus. Rats in the other four groups (Groups D-G), Co8-Co9 underwent 4 weeks of compression to induce moderate disc degeneration followed by 2 weeks, 4 weeks, 6 weeks, and 8 weeks of distraction, respectively. Caudal vertebrae were harvested and disc height, T2 signal intensity of the discs, disc morphology, total glycosaminoglycan content of the nucleus pulposus and the structure of the Co8-Co9 end plate were evaluated.After 4 weeks of compression, the intervertebral height and T2 signal intensity of Co8-Co9 vertebrae of rats in Groups B to G were significantly reduced compared with Group A (sham group, all p.0001). Histological scores of rats in Group B averaged 10.14 and the total glycosaminoglycan (GAG) of nucleus pulposus averaged 238.21μg GAG/ng DNA. The bony end plate structure showed significant changes in comparison with the control Group. After 2 weeks to 8 weeks of traction, the disc space and T2 signal intensity of Co8-Co9 vertebrae in Group E were significantly recovered compared to that of rats in Group B (p.0001), and the intervertebral height of the Co8-Co9 in Group D, Group F, and Group G when compared with Group B (p.0001). Meanwhile, the T2 signal intensity of Co8-Co9 in Group D, F, and G when compared with Group B (p.001). Histological scores dropped from an average of 10.14 in Group B to 5.57 in Group E, and 5.86 in Group F (all p.0001). Furthermore, the total GAG content of the nucleus pulposus increased from an average of 238.21μg GAG/ng DNA in Group B to 601.02μg GAG/ng DNA in Group E (p.0001). The number of pores of end plates in rats in Groups D and E both were significantly increased when compared to that of rats in Group B (Groups D vs Groups B, p.05; Groups E vs Groups B, p.0001).A mechanical degenerative model was successfully established by using a custom-made device. We demonstrated that disc degeneration is a cascade of biochemical, mechanical, and structural changes mediated by cells in an abnormal mechanical environment. Not all levels of disc degeneration can be regenerated or repaired. Regeneration or recovery of disc degeneration requires specific conditions. Based on the immobilization-traction mode, the cascade cycle of disc degeneration is interrupted. Traction of 2 to 6 weeks is a sensitive period for regeneration of the degenerative disc. Moreover, the duration and extent of the traction loading must be moderately controllable, and beyond the limits that can lead to significant degeneration. These data may help improve our understanding of the pathogenesis of clinical disc degeneration and how to optimize the use of traction devices for possible regeneration.

BACKGROUND CONTEXT One of the most common exams in a radiologist practice is the lumbar spine. Manual measurements, examination and interpretation are laborious and can vary within and across practices. Artificial intelligence (AI) provides an opportunity to decrease time and has the potential for reducing variability between readers and improving measurement accuracy. PURPOSE This study was initiated to look at imaging data measuring disc height from a clinical population of patients treated for disc degeneration and assess variance between two board-certified radiologists and an investigational AI or auto-segmentation technology (SmartSoft, CoLumbo). STUDY DESIGN/SETTING Patient MRI studies evaluated disc height measurements and calculated disc height change over 12 months. Comparisons between auto-segmentation technology and radiologists looked for differences of not only height but variance in measurement between the auto-segmentation technology and radiologists. PATIENT SAMPLE An initial MRI was specified up to 6 months prior to treatment and a follow-up MRI within 6 months after a 12-month endpoint. Treatments were agnostic to the intradiscal intervention. MRI disc heights were assessed pretreatment and post-treatment at the treated levels for 107 patients. OUTCOME MEASURES A change in disc height was calculated as the difference of the pretreatment height minus the post-treatment height. The average height and the standard deviation were determined for a comparison between the radiologists and auto-segmentation technology. Methods Two board-certified radiologists, blinded to treatment and levels treated, measured all lumbar disc levels at a mid-sagittal central location. A comparison was made between the two radiologists and an auto segmentation software (SmartSoft, Columbo) that read, segmented, and measured the MRI images. The software measured disc height as an average value of three parasagittal measurements for the anterior margin, midcentral sagittal, and the posterior margin. The midcentral sagittal slice was most comparable to the defined criteria used by the radiologists and used for analysis. Statistical analysis was performed using Minitab software (version 19.2020.1). Results Interobserver measurement between the radiologists reflected the complexity and irregularity of the vertebral plate. Radiologist 2 measurements were consistently lower for both pretreatment and post-treatment (mean differences of 0.51 to 0.85 mm). However, the variances of the height measurements for both radiologists across all treatment groups were not statistically different (p = .630; Bartlett's test). The SmartSoft mid-central sagittal measurements, paired to criteria used for the radiologist readings, were statistically different compared to either of the radiologists for treatment groups at pretreatment and at post-treatment (p Conclusions Disc height measurements and the calculated disc height change over 12 months compared auto-segmentation technology with two board-certified radiologists. Interobserver variability was noted between the two radiologist's measurements. The pooled variance disc height change for the SmartSoft Technology was less than the pooled variance of the radiologists. While radiologist 1 was not significantly different in variance vs the SmartSoft Technology, the other radiologist was significantly different. SmartSoft Technology could provide a more consistent measurement as the variance in a clinical study assessment where MRI and disc height are measured might be critical. Separately, the acquisition and measurement automation yields a less variable assessment with fractional time commitment. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Posterolateral fusion (PLF) and lumbar interbody fusion (LIF) are the commonly used techniques for the treatment of lumbar degenerative diseases. Although the superiority of PLF or LIF remains controversial, LIF technique provides the potential advantages of anterior column supports and 360° arthrodesis. The most commonly used LIF technique is transforaminal LIF (TLIF). Lateral approaches including extreme LIF (XLIF) and the subsequent oblique LIF (OLIF), have been accepted by an increasing number of spine surgeons due to their unique advantages. Previous studies revealed that radiological outcomes significantly varied among PLF, TLIF, XLIF and OLIF, suggesting their different biomechanical properties. PURPOSE To compare the biomechanical differences among PLF, TLIF, XLIF and OLIF construct and determine which surgical construct was most beneficialto the segmental stability and cage subsidence resistance. STUDY DESIGN/SETTING a finite element (FE) analysis. OUTCOME MEASURES The ranges of motion (ROMs) and stress peaks in the cortical endplate, cancellous bone and posterior instrumentations were compared among the five constructs. METHODS An intact FE model of the L3-L5 lumbar spine was constructed. After validation, the PLF, TLIF with a banana-shaped cage, TLIF with a straight cage, XLIF and OLIF procedures were simulated at the L4/5 level. A bilateral pedicle screw fixation was added in each construct. The TLIF banana-shaped cage was placed on the anterior one-third portion of the endplate. The TLIF straight cage was placed around the midpoint of the endplate and was diagonally positioned at an angle of 45° . The XLIF cage was placed at the mid-endplate and the OLIF cage was placed more anteriorly. An axial preload of 400 N was imposed on the superior surface of L3 to simulate the corresponding physiologic compression. Another 8 Nm was applied on L3 to simulate flexion, extension, bending and axial rotation. RESULTS The PLF construct has much higher ROMs than the LIF constructs (0.44° to -1.05° vs 0.29° to -0.72°). TLIF with a straight cage induces the highest stress peak in the endplate and cancellous bone (23.2-63.7 MPa and 0.69-2.03 MPa, respectively), followedby TLIF with a banana-shaped cage (23.7-44.8 MPa and 0.6-1.36 MPa, respectively). OLIF (16.76-32.41 MPa and 0.54-1.07 MPa, respectively) and XLIF (17.01-35.34 MPa and 0.56-1.12 MPa, respectively) constructs induces much lower stress peaks in the endplate and cancellous bone. In the PLF construct, the stress peaks in the posterior instrument range from 244.6 MPa to 377.4 MPa, which are significantly higher than those in the LIF constructs (123.9-237.4 MPa). CONCLUSIONS The PLF construct had\s less stability than the LIF construct due to the higher ROMs and stress peaks in the posterior instrument. TLIF with a banana-shaped cage outperforms TLIF with a straight cage in decreasing the stress peaks in the endplate and cancellous bone, as the banana-shaped cage is ideally located more anteriorly and placed on the strong cortical rim of the endplate. Compared with TLIF constructs, the much larger cages used in the OLIF and XLIF constructs induce significantly fewer stress peaks and increase homogeneous stress distributions in the endplate cancellous bone, which was beneficial to the subsidence resistance and maintenance of disc height and segmental angle. FDA DEVICE/DRUG STATUS XLIF (Approved for this indication), OLIF (Approved for this indication)

BACKGROUND CONTEXT Postoperative subsidence of the transforaminal lumbar interbody fusion (TLIF) cages can result in loss of lordosis and foraminal height, and in some cases recurrence of nerve root impingement and radicular symptoms. PURPOSE The purpose of this study is to determine factors associated with TLIF cage subsidence. Specifically, we sought to determine if preoperative disc height compared to cage height could be used to predict TLIF interbody cage subsidence. STUDY DESIGN/SETTING Retrospective case-control study. PATIENT SAMPLE We identified 127 patients with complete imaging who met our inclusion criteria, with a mean clinical follow up of 27 months. OUTCOME MEASURES The primary outcome of this study was presence of cage subsidence identified with radiograph or CT. METHODS We retrospectively reviewed all patients undergoing instrumented TLIF from two institutions between July 2004 and June 2014. Postoperative imaging studies (radiographs and CT) were evaluated for evidence of implant subsidence. Preoperative disc height was measured for the operative and adjacent level disc heights. The delta between cage height and disc heights were measured and compared between groups. RESULTS Fifty four patients (44.3%) had evidence of interbody cage subsidence. Average cage subsidence was 5.5mm, with a range of 2.2–10.8mm. We found implant height was significantly higher in the subsidence group (12.6mm) when compared to the nonsubsidence group (11.2mm). Additionally, the delta between cage height and preoperative disc height was significantly larger in the subsidence group delta (5.5mm vs. 3.9mm). Similarly, the delta between cage height and preoperative adjacent level disc height was also significantly larger (1.2mm vs. 3.8mm). CONCLUSIONS This study demonstrates that preoperative disc height and preoperative adjacent level disc height can be used to template TLIF cage height to potentially decrease rates of subsidence. Larger cages subsided more frequently than smaller cages. Patients with evidence of subsidence had larger deltas between cage height and preoperative disc height. Similarly, a significant difference existed if preoperative adjacent level disc height was compared to cage height. This demonstrates that preoperative imaging should be used for TLIF cage height templating to avoid subsidence.

BACKGROUND CONTEXT Lumbar fusion surgery can be performed through either anterior, lateral or posterior approaches. Although the relative advantage of anterior lumbar surgeries for the restoration of sagittal balance in spinal deformity is well-acknowledged, the comparative utility of these approaches in maintaining sagittal alignment following single level lumbar fusion remains unclear. PURPOSE A systematic review of the current literature was performed to assess the relative change in sagittal lumbar parameters including whole lumbar lordosis (WLL), segmental lumbar lordosis (SLL) and disc height (DH) following lumbar fusion using various approaches. STUDY DESIGN/SETTING Systematic review and meta-analysis. PATIENT SAMPLE All subjects in studies reporting imaging outcomes following single-level lumbar fusion, according to inclusion and exclusion criteria. OUTCOME MEASURES Lumbar sagittal parameters (SLL and WLL) and DH. METHODS A computerized literature search of all articles published up to April 17, 2017 was performed using PubMed and Cochrane databases. The following keywords were used: “anterior lumbar interbody fusion”, “ALIF”, “posterior lumbar interbody fusion”, “PLIF”, “trans-foraminal lumbar interbody fusion”, “TLIF”, “lumbar 360° fusion”, “circumferential lumbar fusion”, “combined anterior and posterior lumbar fusion”, “extreme lateral interbody fusion”, “LLIF”, “lateral lumbar interbody fusion”, “LLIF”, “direct lateral interbody fusion”, “DLIF”, “extraforaminal lumbar interbody fusion”, “ELIF”, with different combinations of operators including “AND”, “NOT” and “OR”. All studies were scored based on Methodological Index for NonRandomized Studies (MINORS) criteria. Pairwise comparisons of the fusion approach effect sizes were performed for the three imaging parameters. RESULTS A total of 1,563 articles under “ALIF”, 2,075 articles under “PLIF”, 1,032 articles under “TLIF”, 1,082 articles under “LLIF” and 894 under “circumferential lumbar fusion” were identified. The articles were further stratified on the basis of number of fusion levels. Only studies reporting relevant imaging outcomes following single-level fusion for degenerative pathologies were included in the final analysis. Using this strategy, a total of 14, 27, 25, 11 and 3 studies were included under ALIF, PLIF, TLIF, minimally invasive-TLIF and LLIF, respectively. Based on pairwise comparisons, ALIF significantly improved WLL and DH restoration as compared to all the other fusion modalities [ALIF vs. PLIF:2.5 (0.5–4.6) vs. 1.5 (0.2–2.4), p CONCLUSIONS Based on a systematic review of the literature, ALIF offers a significantly improved restoration of lumbar sagittal parameters following single-level lumbar fusion.

The optimal animal model for in vivo testing of spinal implants, particularly total or partial disc replacement devices, has not yet been determined. Mechanical and morphological similarities of calf and human spines have been reported; however, limitations of the calf model include open growth plates and oversized vertebrae with growth. Mature runt cows (Corrientes breed) may avoid these limitations.This study compared vertebral morphology and biomechanical properties of human and runt cow lumbar motion segments.In vivo disc pressure measurements were obtained in six mature runt cows at L4-L5. In vitro evaluation was performed on these same segments and repeated on 12 human motion segments.Disc pressures were measured in vivo in runt cow (Corrientes breed) L45 discs using a percutaneous transducer with the animal performing various activities. These motion segments were then harvested and morphologic and biomechanical evaluations (disc pressure in compression, flexibility tests to 7.5Nm) were performed on both cow and male human L23 and L45 segments.The transverse lumbar disc dimensions were slightly smaller for (mixed gender) cow versus (male) humans, but were within the range of reported (mixed gender) human values. The mean+/-SD disc height was smaller for runt cow (7+/-1mm) versus human discs (13+/-2mm, p.001). The vertebral bodies of the cow were approximately twice as tall as the human. In vitro testing revealed significantly greater disc pressure response to applied axial loading in the runt cow versus humans (1.27+/-0.18 vs. 0.84+/-0.15kPa/N, respectively) but similar overall stiffness (2.15+/-0.71 vs. 1.91+/-0.94kN/mm, respectively). Runt cow and human segment flexibility curves were similar with the following exceptions: runt cow stiffness was approximately 40% greater in torsion (p.05), runt cow segment lateral bending motion was greater versus humans (range of motion by 30%, neutral zone by 100%; both p.05), and flexion range of motion tended to be smaller in runt cow versus human specimens (by approximately 40%, p=NS). In vivo, the standing disc pressure in the runt cow was 0.80+/-0.24MPa.Although no animal replicates the human motion segment, the runt cow lumbar spine had a number of biomechanical and morphological measurements within the range of human values. The closed physes and temporally stable morphology of the mature runt cow may make this model more suitable versus standard calf models for human intradiscal implant studies.

Purpose of study: It is commonly held that accelerated degeneration occurs in the motion segment adjacent to a fusion. Most studies pay particular attention only to the motion segments immediately adjacent to the fusion. Objective: To examine the long-term effects of posterolateral instrumented lumbar fusion (LF) on all the unfused lumbar segments. Methods used: A total of 212 unfused lumbar segments were evaluated in 62 patients, 32 men and 30 women with a mean age of 45.92 years (range, 23 to 67) in whom LF had been performed. The mean number of fused segments per patient was 1.53 (range, 1 to 4). The fused levels were LA–L5 (19), L5–S1 (15), L4–S1 (11), L3–L5 (9), L3–S1 (4), L2–L3 (1), L2–L5 (1) and L2–S1 (1). Two independent observers, using the AutoCad 2000 and the distortion-compensated method [1], measured lordosis, disc height (DAXc) and dorso-ventral displacement (Dc) of all the noninstrumental lumbar segments in digitized standing lateral radiographs taken immediately before and after surgery, and at a mean follow-up of 7.5 years (range, 4 to 11.5). The collected data were analyzed along with spinopelvic balance and sagittal angular parameters. of findings: DAXc and Dc of the 31 segments below the LF did not show significant differences between before surgery and follow-up. At the first (62 patients), second (59) and third (45) segments above the LF, the same significant (p Relationship between findings and existing knowledge: Biochemical studies in human cadaver support the view that fusion in the lumbar spine is likely to be associated with an increased incidence of degeneration at adjacent levels, but there is little reliable information on the incidence of juxtafusion degeneration from the few long-term studies of lumbar spine fusion reported in the literature. Overall significance of findings: After an instrumented lumbar fusion, radiographic changes suggesting disc degeneration appear homogeneously at several levels cephalad to the fusion area and seem to be determined more by individual characteristics than by fusion itself. Disclosures: Device or drug: pedicle screws. Status: approved. Conflict of interest: No conflicts.

Purpose of study: It has been repeatedly demonstrated that disc denucleation ultimately results in segment destabilization and progressive collapse of disc space. Microdiscectomy alone for the treatment of primary herniated nucleus pulposus (HNP) has been only partially effective because of clinically relevant recurrence. To provide stabilization to the denucleated disc, while eliminating the potential for recurrent herniations, we propose the use of an in situ polymerizable protein hydrogel device (BioDisc). When introduced as a liquid into the denucleated disc space, the implant cross-links to form a durable hydrogel that maintains disc height and segmental stability while preserving motion. Methods used: Fresh calf lumbar segments (single bone-disc-bone [BDB] segment) were modeled as a worst-case stability scenario by full removal of the posterior spinal segments. Baseline compressive properties were obtained by cyclically loading 300 to 1,200 N for 1,000 cycles, and recording compressibility and overall segment height over each cycle. The disc of each BDB segment was then thoroughly denucleated with spinal rongeurs, following an anterior, posterior of posterolateral approach, and re-evaluated under identical test conditions to assess loss of height and segmental stability. The denucleation was then repaired with BioDisc, whereupon the segment was evaluated as above. Subsequently, each BDB segment was cyclically loaded to the equivalent of 1,200 N through 10 million cycles with interval evaluations. of findings: After the removal of the disc nuclear material, BDB segments exhibited an immediate loss in disc height. Repair of the disc denucleation with BioDisc preserved the initial (predenucleation) disc height. During monotonic loading through 10 million cycles, the repaired BDB segment demonstrated a minimal reduction in overall height and retained the axial compressibility of the motion segment. Upon completion of each test, all samples were grossly inspected (by sectioning through the repaired region) and the implanted BioDisc material was observed to be intact within the nuclear space. Relationship between findings and existing knowledge: The BioDisc implant has been shown to possess suitable biomechanical properties to stabilize a denucleated intervertebral disc. Mechanical durability of the implant in a severe model construct was demonstrated through 10 million compressive loading cycles. Overall significance of findings: These data demonstrate the potential utility of BioDisc for the repair of denucleated intervertebral discs in the treatment of HNP. Disclosures: No disclosures. Conflict of interest: Umit Yuksel, and; Steven Walsh: employees of Cryolife Inc.

stiffness that, in addition to well characterized mechanisms of instability including disc height loss and dehydration, may also contribute to decreased segmental stability resulting in conditions including disc prolapse and predispose to spondylolisthesis. Continued testing and computational modeling may elucidate the relative contribution of annular yield to overall segmental instability. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.

Purpose of study: The spectrum of discogenic pain syndrome ranges from internal disc disruption (IDD), degenerative disc disease (DDD) and segmental instability. After failure of conservative treatment, surgical options would include fusion. This study was performed to determine whether the results of fusion differ between IDD and DDD. Methods used: Patient and radiographic data were entered prospectively on 118 patients who underwent anterior lumbar interbody fusion for treatment of low back pain. Chart and radiographic review completed data sets. Of the 118 patients, 53 had IDD and 65 had DDD. We evaluated each group for clinical outcome, Oswestery scores, and radiographically for fusion, subsidence, and lordosis. In patients with IDD, average age was 39 years. There were 15 smokers (28%) and 16 patients (30%) were involved in workman's compensation litigation. Twelve patients had previous lumbar spine surgery. Two level fusions were performed in 6 patients. Average follow-up period was 29 months. In patients with DDD, average age was 44 years. There were 16 smokers (25%) and 11 patients (17%) were involved in workman's compensation litigation. Twenty-four patients had previous lumbar spine surgery. Two level fusions were performed in 2 patients. Average follow-up period was 27 months. In both groups minimal follow-up was 12 months. of findings: In patients with IDD, excellent/good results were obtained in 44 patients (83%) and fair/poor results in 9 patients (17%). Oswestery Scores were an average of 38 points pre-op which improve to 24 points at 3 months and to 20 points at the last follow-up visit. Radiographic fusion occurred in 50 patients (94%). The intervertebral height was increased from 4.5 mm pre-op to 7 mm post op and then decreased due to subsidence to 5 mm. Lumbar lordosis at the fused level measured an average of 17 degrees pre-op, 20 degrees immediately post-op and 21 degrees at last follow-up. In patients with DDD, excellent/good results were obtained in 60 patients (92%) and fair/poor results in 5 patients (8%). Oswestery Scores were an average of 36 points pre-op, which improve to 20 points at 3 months and to 10 points at the last follow-up visit. Radiographic fusion occurred in all 65 patients (100%). The intervertebral height was increased from 3 mm pre-op to 7 mm post op and then decreased due to subsidence to 5.5 mm. Lumbar lordosis at the fused level measured an average of 14 degrees pre-op, 21.4 degrees immediately post-op and 21.7 degrees at last follow-up. Relationship between findings and existing knowledge: This study demonstrates that anterior lumbar interbody fusion provides excellent outcomes both clinically and radiographically when indicated for treatment of discogenic low back pain. Overall significance of findings: Radiographically, restoration of lordosis and disc height was better achieved in patients with DDD. In addition, we found that patients with DDD had better clinical outcomes than patients with IDD. Disclosures: No disclosures. Conflict of interest: Thomas A. Zdeblick, grant research, consultant, Medtronic.