Risk Of Adjacent Segment Disease Research Articles

Development and validation of a nomogram to predict the risk of adjacent segment disease after transforaminal lumbar interbody fusion in patients with lumbar degenerative diseases

BackgroundAdjacent segment disease (ASD) is a common and serious complication that can develop in the mid- to long-term after lumbar fusion surgery. However, the underlying mechanisms of ASD are not yet fully understood. This study aimed to develop and validate a risk prediction model for ASD in patients who underwent transforaminal lumbar interbody fusion (TLIF) for lumbar degenerative diseases.MethodsPatients with lumbar degenerative disease who underwent TLIF between January 2015 and December 2016 were included in the retrospective study. The participants were divided into two groups: ASD and non-ASD. Univariate and multivariate logistic regression analyses were performed to identify factors influencing ASD after TLIF surgery. The receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) were used to evaluate the model’s discrimination, calibration and clinical value, respectively.ResultsA total of 11.5% (59/513) of patients developed ASD. Higher BMI, lower BMD, higher disc grade, and reduced disc height were identified as independent risk factors for ASD after TLIF. The model demonstrated good discrimination in both the training and validation sets, with calibration and Hosmer-Lemeshow tests confirming accuracy, and DCA demonstrating clinical applicability.ConclusionsThe nomogram model demonstrated promise in predicting ASD in patients who underwent TLIF, aiding clinicians in selecting the most suitable surgical approach and optimizing surgical decisions.

Comparative Biomechanical Analysis of Anterior Lumbar Interbody Fusion and Bilateral Expandable Transforaminal Lumbar Interbody Fusion Cages: A Finite Element Analysis Study.

Expandable transforaminal lumbar interbody fusion (TLIF) cages could offer an alternative to anterior lumbar interbody fusion (ALIF). Bilateral cage insertion enhances endplate coverage, potentially improving stability and fusion rates and maximizing segmental lordosis. This study aims to compare the biomechanical properties of bilateral expandable TLIF cages to ALIF cages using finite element modeling. We used a validated 3-dimensional finite element model of the lumbar spine. ALIF and TLIF cages were created based on available product data. Our focus was on analyzing spinal motion in the sagittal plane, evaluating forces transmitted through the vertebrae, and comparing an ALIF model with various TLIF cage models. The largest TLIF cage model exhibited a 407.9% increase in flexion motion and a 42.1% decrease in extension motion compared with the ALIF cage. The second largest TLIF cages resulted in more flexion motion and less extension motion compared with ALIF, while smaller cages were inferior to ALIF. ALIF cages were associated with increased adjacent segment motion compared with TLIF cages, primarily in extension. Endplate stress analysis revealed higher stress in the ALIF cage model with a more uniform stress distribution. ALIF cages excel in stabilizing L5 to S1 during flexion, while largest TLIF cages offer superior stability in extension. Large bilateral TLIF cages may provide biomechanical stability comparable to ALIF, especially in extension and could potentially reduce the risk of adjacent segment disease with lower adjacent segment motion.

Prediction of primary admission total charges following cervical disc arthroplasty utilizing machine learning

BACKGROUND CONTEXTCervical disc arthroplasty (CDA) has become an increasingly popular alternative to anterior cervical discectomy and fusion, offering benefits such as motion preservation and reduced risk of adjacent segment disease. Despite its advantages, understanding the economic implications associated with varying patient and hospital factors remains critical. PURPOSETo evaluate how hospital size, geographic region, and patient-specific variables influence charges associated with the primary admission period following CDA. STUDY DESIGNA retrospective analysis using machine learning models to predict and analyze charge factors associated with CDA. PATIENT SAMPLEData from the National Inpatient Sample (NIS) database from 2016 to 2020 was used, focusing on patients undergoing CDA. OUTCOME MEASURESThe primary outcome was total charge associated with the primary admission for CDA, analyzed against patient demographics, hospital characteristics, and regional economic conditions. METHODSMultivariate linear regression and machine learning algorithms including logistic regression, random forest, and gradient boosting trees were employed to assess their predictive power on charge outcomes. Statistical significance was set at the 0.003 level after applying a Bonferroni correction. RESULTSThe analysis included 3,772 eligible CDA cases. Major predictors of charge identified were hospital size and ownership type, with large and privately owned hospitals associated with higher charges (p<.001). The Western region of the U.S. also showed significantly higher charges compared to the Northeast (p<.001). The gradient boosting trees model showed the highest accuracy (AUC=85.6%). Length of stay and wage index were significant charge drivers, with each additional inpatient day increasing charges significantly (p<.001) and higher wage index regions correlating with increased charges (p<.001). CONCLUSIONSHospital size, geographic region, and specific patient demographics significantly influence the charges of CDA. Machine learning models proved effective in predicting these charges, suggesting that they could be instrumental in guiding economic decision-making in spine surgery. Future efforts should aim to incorporate these models into broader clinical practice to optimize healthcare spending and enhance patient care outcomes.

Changes in Alignment at Untreated Vertebral Levels Following Short-Segment Fusion Using Personalized Interbody Cages: Leveraging Personalized Medicine to Reduce the Risk of Reoperation.

An abnormal postoperative lordosis distribution index (LDI), which quantifies the ratio between the lordosis at L4 to S1 and the lordosis at L1 to S1, contributes to the development of adjacent segment disease and increased revision rates in patients undergoing short-segment lumbar intervertebral fusions. Incorporating preoperative spinopelvic parameters and LDI into the surgical plan for short-segment fusion is important for guiding alignment restoration and preserving normal preoperative alignment in unfused segments. This study examined changes in LDI, segmental lordosis, and lordosis of the unfused levels in patients treated with personalized interbody cage (PIC) implants. This retrospective study evaluated radiographic measurements from 111 consecutively treated patients diagnosed with degenerative spinal conditions and treated with a short-segment fusion of L4 to L5, L5 to S1, or L4 to S1 using PIC implant(s) within 6 months of the fusion procedure. Comparisons of intervertebral lordosis for treated and untreated levels as well as LDI pre- and postoperatively were performed. In patients with a preoperative hypolordotic distribution (LDI < 50%), statistically significant increases were found in LDI postoperatively, approaching the normal LDI range (LDI 50%-80%). Likewise, patients with hyperlordotic distribution preoperatively (LDI > 80%) experienced a decrease in LDI postoperatively, trending toward the normal range, although the changes were not statistically significant. Intervertebral lordosis for the L5 to S1 level increased significantly following the placement of a PIC in the normal and hypolordotic LDI groups. Changes in intervertebral lordosis for L5 to S1 were not significant for patients with preoperative hyperlordotic LDI. Reciprocal changes in intervertebral lordosis at L1 to L4 were not observed in any groups. PIC implants may provide a benefit for patients, particularly those with hypolordotic distributions preoperatively. They have the potential to further improve patient outcomes by helping surgeons to achieve patient-specific lordosis goals, which may help to reduce the risk of adjacent segment disease and revisions in patients undergoing short-segment lumbar intervertebral fusions. Personalized implants can help surgeons achieve patient-specific alignment goals, potentially prevent adjacent segment disease, and reduce long-term reinterventions.

Mismatch Between Pelvic Incidence and Lumbar Lordosis After Personalized Interbody Fusion: The Importance of Preoperative Planning and Alignment in Degenerative Spine Diseases.

Emerging data have highlighted the significance of planning and aligning total and segmental lumbar lordosis with pelvic morphology when performing short-segment fusion with the goal of reducing the risk of adjacent segment disease while also decreasing spine-related disability. This study evaluates the impact of personalized interbody implants in restoring pelvic incidence-lumbar lordosis (PI-LL) mismatch compared with a similar study using stock interbody implants. This multicenter retrospective analysis assessed radiographic pre- and postoperative spinopelvic alignment (PI-LL) in patients who underwent 1- or 2-level lumbar fusions with personalized interbody implants for degenerative (nondeformity) indications. The aim was to assess the incidence of malalignment (PI-LL ≥ 10°) both before and after fusion surgery and to determine the rate of alignment preservation and/or correction in this population. There were 135 patients included in this study. Of 83 patients who were aligned preoperatively, alignment was preserved in 76 (91.6%) and worsened in 7 (8.4%). Among the 52 preoperatively malaligned patients, alignment was restored in 23 (44.2%), and 29 (55.8%) were not fully corrected. Among patients who were preoperatively aligned, there was no statistically significant difference in either the "preserved" or "worsened" groups between stock devices and personalized interbody devices. In contrast, among patients who were preoperatively malaligned, there was a statistically significant increase in the "restored" group (P = 0.046) and a statistically significant decrease in the "worsened" groups in patients with personalized interbodies compared with historical stock device data (P < 0.05). Compared with a historical cohort with stock implants, personalized interbody implants in short-segment fusions have shown a statistically significant improvement in restoring patients to normative PI-LL. Using 3-dimensional preoperative planning combined with personalized implants provides an important tool for planning and achieving improvement in spinopelvic parameters.

Monocentric Retrospective Analysis of Clinical Outcomes, Complications, and Adjacent Segment Disease in 507 Patients Undergoing Anterior Cervical Discectomy and Fusion for Degenerative Cervical Myelopathy

BackgroundDegenerative Cervical Myelopathy (DCM) is a leading cause of non-traumatic spinal cord injury. Surgery aims to arrest neurological decline and improve conditions, but controversies surround risks and benefits in elderly patients, outcomes in mild myelopathy, and the risk of adjacent segment disease (ASD). MethodsRetrospective data of patients who underwent ACDF for DCM in our hospital were collected. Patients were stratified by preoperative mJOA (mild, moderate, severe) and age (Under 70, Over 70). Clinical outcomes, complications, and ASD rate were analyzed. We evaluated the relationship between mJOA recovery rate and the risk of complications and various preoperative parameters. Results507 consecutive patients were included in the study, with a mean follow-up of 43.52 months (12-71). Improvement in all outcome variables was observed in mild, moderate and severe myelopathy categories, with elderly patients showing a lower improvement. Except for age, no other variable correlated with mJOA recovery rate. We observed 45 complications (11.1% of patients), with 14 in the U70 group and 31 in the O70 group (p-value<0.001). Age, Charlson Comorbidity index and ASA score were found to be predictors of complications. Fourteen patients (2.8% of total), mean age 54.2, developed radiological and clinical ASD. Most had cranial-level ASD with Pfirmann grade >= 2 before index surgery. ConclusionsMost myelopathic patients improve after ACDF. Elderly patients show a lower improvement and higher complication rates than younger counterparts. ASD rates are low, and younger patients with preexisting cranial level alterations are more susceptible.

Index-level fusion and adjacent segment disease following dynamic stabilization for lumbar degenerative disc disease: illustrative case.

Dynesys dynamic stabilization (DDS) is an alternative to surgical fusion for the operative management of degenerative lumbar spondylosis. Compared to rigid instrumentation and fusion, DDS is purported to preserve a higher degree of spinal range of motion and reduce the risk of developing adjacent segment disease (ASD). A 60-year-old female presented with severe back pain and bilateral leg pain, which had progressed over the prior 4 years. Nine years earlier, she had undergone DDS system implantation at L5-S1 for lumbar stenosis and spondylosis. Repeat imaging revealed an unintended fusion at the index level (L5-S1) and ASD causing severe lateral recess stenosis at L4-5. She underwent DDS system removal, decompression at L4-5, and extension of the fusion to L4. Although DDS has been marketed as a motion-preserving system that avoids fusion and reduces the risk of ASD, unintended index-level fusion and ASD can still occur after DDS system surgery. These potential complications should be assessed when determining the optimal primary surgical treatment for patients with lumbar degenerative disc disease. https://thejns.org/doi/10.3171/CASE24179.

Lumbar Apex Position as an Independent Risk Factor for Adjacent Segment Diseases in Patients Undergoing Short-Level Transforaminal Lumbar Interbody Fusion.

Retrospective study. To investigate whether lumbar apex position had an impact on the development of adjacent segment disease (ASD) following transforaminal lumbar interbody fusion (TLIF). Previous studies have demonstrated that solely concentrating on lumbar lordosis value is not suitable, and neglecting the significance of lumbar apex can lead to mechanical complications. However, the relationship between lumbar apex and ASD is still not well understood. In this retrospective study, 234 consecutive patients who underwent L3-5 or L4-5 TLIF for degenerative diseases were reviewed. The study evaluated the associations between sagittal parameters and pelvic incidence (PI). Patients were labeled "matched" when lumbar apex position aligned with the theoretical target, and "mismatched" when it did not. Multivariate analysis was applied to find the independent risk factors of ASD. In addition, a focused subanalysis was performed based on the lumbar apex position (ideal match, cranial from ideal, and caudal from ideal). After an average follow-up period of 70.6 months, 68 cases were identified as having ASD. Postoperatively, 64.7% (44 of 68) of the patients with ASD exhibited a mismatched lumbar apex, compared with 41% (68 of 166) of those without ASD ( P < 0.001). PI correlated significantly with proximal lordosis (PL) and lordosis distribution index (LDI) but not with distal lordosis (DL). Multivariate analysis identified age, L3-5 fusion, postoperative DL, and postoperative mismatched lumbar apex as independent risk factors of ASD. Upon the subanalysis, it was discovered that there were unique compensatory strategies in the cranial and caudal groups, with notable variations in postoperative DL, PL, and LDI among three groups (all P value of <0.05). Lumbar apex position significantly influenced the risk of ASD. To restore the lumbar apex to its ideal position, a proper value and distribution of DL should be attained. 4.

Biomechanical Effect of Different Posterior Fixation Techniques on Stability and Adjacent Segment Degeneration in Treating Thoracolumbar Burst Fracture With Osteoporosis: A Finite Element Analysis.

Finite element analysis. To investigate the biomechanical effect of four posterior fixation techniques on stability and adjacent segment degeneration in treating thoracolumbar burst fractures with osteoporosis. In terms of stability and adjacent segment degeneration, there remains no consensus or guidelines on the optimal technique for the treatment of thoracolumbar burst fractures in patients with osteoporosis. Images of CT scans were imported into MIMICS and further processed by Geomagic to build three-dimensional models of the T10-L5 region. A v-shaped osteotomy was performed on the L1 vertebral body to simulate a burst fracture in the setting of osteoporosis. Subsequently, four fixation techniques were designed using SolidWorks software. Range of motion (ROM) of the global spine, ROM distribution, ROM of adjacent segment, Von Mises stress on adjacent intervertebral disks, and facet joints were analyzed. Among the four groups, the cortical bone screw fixation (CBT) showed the highest global ROM at 1.86°, while long-segmented pedicle screw fixation (LSPS) had the lowest global ROM at 1.25°. The LSPS had the smallest percentage of ROM of fractured vertebral body to fixed segment at 75.04%, suggesting the highest stability after fixation. The maximum ROM of the adjacent segment was observed in the CBT at 1.32°, while the LSPS exhibited the smallest at 0.89°. However, the LSPS group experienced larger maximum stress on the adjacent intervertebral disks (9.60MPa) and facet joints (3.36MPa), indicating an increasing risk of adjacent segment disease. LSPS provided the greatest stability, while CBT provided the smallest amount of stability. However, the elevated stress on adjacent intervertebral disks and facet joints after LSPS fixation increased the possibility of adjacent segment degeneration. Cement-augmented pedicle screw fixation (CAPS) and combined cortical bone screw and pedicle screw fixation (CBT-PS) demonstrated significant biomechanical advantages in providing moderate fixation strength while reducing stress on the intervertebral disks and facet joints.

Laminectomy Adjacent to Instrumented Fusion Increases Adjacent Segment Disease.

Retrospective cohort. To determine if performing a simultaneous laminectomy at an unfused level adjacent to an instrumented fusion increases the risk of adjacent segment disease(ASD). Laminectomy adjacent to instrumented fusion has uncertain outcomes. The increased mechanical forces at the unfused laminectomy may lead to more ASD. Few studies have examined the development of ASD with regards to laminectomy performed adjacent to instrumented fusions. 789 patients underwent instrumented lumbar fusion and laminectomy at the same level(s) (n=676) or with an additional adjacent level laminectomy (n=113) with a minimum of 2-year follow-up. Diagnoses were degenerative spondylosis (n=241), degenerative spondylolisthesis (n=485) and isthmic spondylolisthesis (n=63) in addition to central stenosis. Primary outcome measures included development of ASD, time to development of ASD, revision surgery, and time to revision surgery. The adjacent laminectomy group developed ASD at a significantly greater rate of 57.5% (n=65), compared with 35.2% (n=238) of the non-adjacent laminectomy group (P<0.001). Revision surgery rate was also greater in the adjacent laminectomy group (22.1% v 13.5%, P<0.001). There was no difference in time to revision surgery (31.1 v 32.6mo, P=0.71) or time to ASD development (31.2 v 32.3mo, P=0.72). ODI and VAS scores did not differ, nor did patient baseline demographics including sex, BMI, Charleston Comorbidity Index, and tobacco use. The exception was the adjacent laminectomy group average age was 67.6 while the non-adjacent laminectomy group average age was 62.3 (P<0.001). However, age was not found to be an independent predictor of ASD development (P=0.44). Surgeons should be cautious when performing a laminectomy adjacent to an instrumented fusion, as this increases the rate of ASD as well as revision surgery.

Postoperative Adjacent Segment Disease in Minimally Invasive Transforaminal Lumbar Interbody Fusion with Adjacent Laminectomy for Grade I-II Spondylolisthesis and Adjacent Spinal Stenosis

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. 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. 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. 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.

Radiographic Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion (ACDF): A Systematic Review and Meta-Analysis.

Systematic review and meta-analysis. To assess the radiographic risk factors for adjacent segment disease (ASD) following anterior cervical discectomy and fusion (ACDF) for degenerative cervical spine pathologies. PubMed, Embase and the Cochrane Library databases were searched up to December 2023. The primary inclusion criteria were degenerative spinal conditions treated with ACDF, comparing radiological parameters in patients with and without postoperative ASD. The radiographic parameters included intervertebral disc height, cervical sagittal alignment, sagittal segmental alignment, range of motion, segmental height, T1 slope, sagittal vertical axis (SVA), thoracic inlet angle (TIA), and plate to disc distance (PPD). Risk of bias was assessed for all studies. The Cochrane Review Manager was utilized to perform the meta-analysis. From 7044 articles, 13 retrospective studies were included in the final analysis. Three studies had "not serious" bias and the other 10 studies had serious or very serious bias. The total number of patients in the included studies was 1799 patients. Five studies included single-level ACDF, 2 studies included multi-level ACDF, and 6 studies included single or multi-level ACDF. On meta-analysis, the significant risk factors associated with ASD development were reduced postoperative cervical lordosis (mean difference [MD] = 3.35°, P = .002), reduced last-follow-up cervical lordosis (MD = -3.02°, P = .0003), increased preoperative to postoperative cervical sagittal alignment change (MD = -3.68°, P = .03), and the presence of developmental cervical canal stenosis (Odds ratio [OR] = 4.17, P < .001). Decreased postoperative cervical lordosis, greater change in cervical sagittal alignment and developmental cervical canal stenosis were associated with an increased risk of ASD following ACDF.

Impact of osteoporosis and Cement-Augmented fusion on adjacent spinal levels Post-Fusion Surgery: Patient-Specific finite element analysis

Cement-augmentation is a technique commonly used during posterior lumbar instrumented fusion (PLIF) to reinforce compromised osteoporotic vertebral bone, minimize the risk of loosening screws, enhance stability, and improve overall surgical outcomes. In this study, we introduce a novel segmented vertebral body regional modeling approach to investigate the effects of osteoporosis and cement-augmented lumbar fusion on disc biomechanics at spinal levels adjacent to the fused vertebrae. Using our previously validated personalized-poroelastic-osteoligamentous FE model of the spine, fusion was simulated at L4-L5, and the biomechanics of adjacent levels were studied for 30 patients (non-osteoporotic patients (N = 15), osteoporotic patients (N = 15)). PLIF models, with and without cement-augmentation, were developed and compared after an 8 h-rest period (200 N), following a 16 h-cyclic compressive loading of 500–1000 N (40 and 20 min, respectively). Movement in different directions (flexion/ extension/ lateral bending/ axial rotation) was simulated using 10Nm moment before and after cyclic loading. The material mapping algorithm was validated by comparing the results of voxel-based and parametric models. The FE cement-augmented models, subject to daily activity loading, demonstrated significant differences in disc height loss and fluid loss as compared to non-cemented models. The calculated axial stress and fiber strain values were also significantly higher for these models. This work demonstrates that although osteoporosis does not significantly alter the time-dependent characteristics of adjacent IVDs post-surgery, cement-augmentation increases the risk of adjacent segment disease (ASD) incidence. A holistic understanding of the trade-offs and long-term complex interplay between structural reinforcement modalities, including cement augmentation, and altered biomechanics warrants further investigation.

Prediction Model and Risk Factor Analysis of Adjacent Segment Disease After L4-5 Transforaminal Lumbar Interbody Fusion Through Preoperative Radiographic Features.

A retrospective study. To investigate the risk of adjacent segment disease (ASD) after L4-5 transforaminal lumbar interbody fusion (TLIF) in patients diagnosed with lumbar spinal stenosis (LSS), a prediction model for ASD is established and validated. A retrospective study was carried out on a sample of 290 patients who underwent L4-5 TLIF at Zhongda Hospital, Southeast University, from January 2015 to January 2021. The study collected baseline data and preoperative radiographic features of L3-4 and L5-S1. The determination of the outcome variable was based on X-ray results spanning over 24months and JOA scores. Multivariate logistic regression was used to identify the risk factors in constructing a nomogram. Independent risk factors for L3-4 degeneration after TLIF included osteoarthritis of L3-4 facet joints, L3-4 foraminal stenosis, L4 upper endplate osteochondritis, L3-4 local lordosis angle, and L3-4 spinal stenosis. Independent risk factors for L5-S1 degeneration after TLIF included osteoarthritis of L5-S1 facet joints, L5-S1 intervertebral disc degeneration, L5-S1 spinal stenosis, L5-S1 coronal imbalance, and S1 upper endplate osteochondritis. A predictive model was developed. The AUC for the prediction models at L3-4 and L5-S1 were .945 and .956. The calibration curve demonstrated good consistency between the predicted and actual probabilities. The DCA curve indicated the clinical benefit and practical value of this predictive model. This study established nomograms for postoperative degeneration at L3-4 and L5-S1 based on selected preoperative radiographic features. These models provide a valuable auxiliary decision-making system for clinicians and aid in early surgical decisions.

Non-linear Effect of Preexisting Cranial Adjacent Disc Degeneration on Cumulative 12-year Revision Risk Following Lumbar Fusions.

Retrospective analysis of prospectively collected data. To evaluate how preexisting adjacent segment degeneration status impacts revision risk for adjacent segment disease (ASD) after lumbar fusions. ASD incurs late reoperations after lumbar fusion surgeries. ASD pathogenesis is multifactorial. Preexisting adjacent segment degeneration measured by Pfirrmann is suggested as one of the predisposing factors. We sought to find deeper insights into this association by using a more granular degeneration measure, the Combined imaging score (CIS). A total of 197 consecutive lumbar fusions for degenerative pathologies were enrolled in a prospective follow-up (median 12 years). Preoperative cranial adjacent segment degeneration status was determined using Pfirrmann and CIS, which utilizes both radiographs and magnetic resonance imaging. Based on CIS, patients were trichotomized into tertiles (CIS <7, CIS 7-10, and CIS >10). The cumulative ASD revision risk was determined for each tertile. After adjusting for age, sex, body mass index, sacral fixation, and fusion length, hazard ratios (95% confidence intervals, CI) for ASD revisions were determined for each Pfirrmann and CIS score. Patients in the intermediate CIS tertile had a cumulative ASD revision risk of 25.4% (17.0% to 37.0%), while both milder degeneration (CIS <7) [13.2% (6.5% to 25.8%)] and end-stage degeneration (CIS >10) [13.6% (7.0% to 25.5%)] appeared to be protective against surgical ASD. Pfirrmann failed to show a significant association with ASD revision risk. Adjusted analysis of CIS suggested increased ASD revisions after CIS 7, which turned contrariwise after CIS 10. The effect of preexisting adjacent segment degeneration on ASD reoperation risk is not linear. The risk seems to increase with advancing degeneration but diminish with end-stage degeneration. Therefore, end-stage degenerative segments may be considered to be excluded from fusion constructs. Therapeutic Level III.

The Decline of Lumbar Artificial Disc Replacement.

Lower back pain associated with degenerative disc disease is a common occurrence, with many surgical treatments targeting the degenerated disc to relieve symptoms. Current surgical options for degenerative disc disease primarily consist of a discectomy followed by either spinal fusion or artificial disc replacement, with the former being increasingly more common in the lumbar region despite the risk of adjacent segment disease. Though artificial disc replacement aims to provide an increase in range of motion and decreases risk of adjacent segment disease, surgeons are increasingly opting for spinal fusion in the lumbar region. This review investigates underlying factors that may be contributing to this trend by assessing lumbar artificial disc replacement selection criteria, clinical outcomes, surgical technique, complications, revision burden, and overall cost. While these factors had some role in the physician's decision, ultimately the narrow selection criteria and lack of cost reimbursement by insurance has primarily led to the decline in lumbar artificial disc replacement.

Long-term comparison of anterior (ALIF) versus transforaminal (TLIF) lumbar interbody fusion: a propensity score-matched register-based study.

Anterior (ALIF) and transforaminal (TLIF) lumbar interbody fusion have shown similar clinical outcomes at short- and medium-term follow-ups. Possible advantages of ALIF in the long run could be better disc height and lumbar lordosis and reduced risk of adjacent segment disease. We aimed to study if ALIF could be associated with superior clinical outcomes than TLIF at long-term follow-up. We analysed 535 patients treated with ALIF or TLIF of the L5-S1 spinal segment between 2007 and 2017 who completed long-term follow-up in a national spine registry database (NORspine). We defined treatment success after surgery as at least 30% improvement in Oswestry Disability Index (ODI) at long-term follow-up. Patients treated with ALIF and TLIF and who responded at long term were balanced by propensity score matching. The proportions of successfully treated patients within each group were compared by numbers and percentages with corresponding relative risk. The mean (95%CI) age of the total study population was 50 (49-51) years, and 264 (49%) were females. The mean (95%CI) preoperative ODI score was 40 (39-42), and 174 (33%) had previous spine surgery. Propensity score matching left 120 patients in each treatment group. At a median (95%CI) of 92 (88-97) months after surgery, we found no difference in proportions successfully treated patients with ALIF versus TLIF (68 (58%) versus 77 (65%), RR (95%CI) = 0.88 (0.72 to1.08); p = 0.237). This propensity score-matched national spine register study of patients treated with ALIF versus TLIF of the lumbosacral junction found no differences in proportions of successfully treated patients at long-term follow-up. Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Ehlers-Danlos Syndrome is Associated with Increased Rates of Adjacent Segment Disease Following TLIF: A Propensity Matched Study

Ehlers-Danlos syndrome (EDS) is a collection of connective tissue disorders which are often associated with tissue laxity and disc degeneration. However, the implications of EDS on the risk of adjacent segment disease (ASD) after transforaminal lumbar interbody fusion (TLIF) are not well described. The objective of this study is to compare the rates of ASD among patients with EDS and those without EDS. Patients who underwent 1-3 level TLIF for degenerative disc disease between 2010-2022 were identified using the PearlDiver Mariner all-claims insurance database. Patients with all types of EDS were included. Patients undergoing surgery for tumors, trauma, or infection were excluded. 1:1 propensity matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with ASD in a linear regression model. The primary outcome measure was the development of ASD. The secondary outcomes were the development of pseudoarthrosis, medical complications, and surgical complications. Propensity matching resulted in 2 equal groups of 85 patients who did or did not have EDS and underwent 1-3 level TLIF. Patients without EDS were less likely to experience ASD (RR 0.18, 95% CI 0.09-0.35, P < 0.001). There was no significant difference between the 2 patient groups with regards to a diagnosis of pseudoarthrosis, and there was no significant difference for all-cause medical and surgical complications between the 2 patient groups. After propensity matching to control for confounding variables, the findings of this study suggest that EDS may be associated with an increased risk of ASD following TLIF. Future studies are needed to corroborate these findings.

Primary anterior lumbar interbody fusion, with and without posterior instrumentation: a 1,377-patient cohort from a multicenter spine registry

BACKGROUND CONTEXTLumbar interbody instrumentation techniques are common and effective surgical options for a variety of lumbar degenerative pathologies. Anterior lumbar interbody fusion (ALIF) has become a versatile and powerful means of decompression, stabilization, and reconstruction. As an anterior only technique, the integrity of the posterior muscle and ligaments remain intact. Adding posterior instrumentation to ALIF is common and may confer benefits in terms of higher fusion rate but could contribute to adjacent segment degeneration due to additional rigidity. Large clinical studies comparing stand-alone ALIF with and without posterior supplementary fixation (ALIF+PSF) are lacking. PURPOSETo compare rates of operative nonunion and adjacent segment disease (ASD) in ALIF with or without posterior instrumentation. STUDY DESIGNRetrospective cohort study. PATIENT SAMPLEAdult patients (≥18 years old) who underwent primary ALIF for lumbar degenerative pathology between levels L4 to S1 over a 12-year period. Exclusion criteria included trauma, cancer, infection, supplemental decompression, noncontiguous fusions, prior lumbar fusions, and other interbody devices. OUTCOME MEASURESReoperation for nonunion and ASD compared between ALIF only and ALIF+PSF. METHODSReoperations were modeled as time-to-events where the follow-up time was defined as the difference between the primary ALIF procedure and the date of the outcome of interest. Crude cumulative reoperation probabilities were reported at 5-years follow-up. Multivariable Cox proportional hazard regression was used to evaluate risk of operative nonunion and for ASD adjusting for patient characteristics. RESULTSThe study consisted of 1,377 cases; 307 ALIF only and 1070 ALIF+PSF. Mean follow-up time was 5.6 years. The 5-year crude nonunion incidence was 2.4% for ALIF only and 0.5% for ALIF+PSF; after adjustment for covariates, a lower operative nonunion risk was observed for ALIF+PSF (HR=0.22, 95% CI=0.06–0.76). Of the patients who are deemed potentially suitable for ALIF alone, one would need to add posterior instrumentation in 53 patients to prevent one case of operative nonunion at a 5-year follow-up (number needed to treat). Five-year operative ASD incidence was 4.3% for ALIF only and 6.2% for ALIF+PSF; with adjustments, no difference was observed between the cohorts (HR=0.96, 95% CI=0.54–1.71). CONCLUSIONSWhile the addition of posterior instrumentation in ALIFs is associated with lower risk of operative nonunion compared with ALIF alone, operative nonunion is rare in both techniques (<5%). Accordingly, surgeons should evaluate the added risks associated with the addition of posterior instrumentation and reserve the supplemental posterior fixation for patients that might be at higher risk for operative nonunion. Rates of operative ASD were not statistically higher with the addition of posterior instrumentation suggesting concern regarding future risk of ASD perhaps should not play a role in considering supplemental posterior instrumentation in ALIF.

54. Does laminectomy adjacent to instrumented fusion increase the risk of adjacent segment disease?

54. Does laminectomy adjacent to instrumented fusion increase the risk of adjacent segment disease?