Risk Factors For Adjacent Segment Disease Research Articles

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.

Risk factors of adjacent-segment disease after short-segment fusion in patients with de novo degenerative lumbar scoliosis.

Short-segment fusion (SSF) is an effective surgical option for appropriately selected patients with de novo degenerative lumbar scoliosis (DNDLS). Considering that DNDLS is frequently accompanied by multisegment degeneration and potential instability across the entire lumbar segments, it is inevitable that unhealthy segments remain after SSF, thereby increasing the potential risk of adjacent-segment disease (ASD) occurrence. Therefore, the authors aimed to identify the risk factors for ASD in patients with DNDLS who underwent SSF. This retrospective study included 80 patients with DNDLS (Cobb angle > 10°) who underwent SSF (1 or 2 levels) between December 2010 and July 2018 with a minimum follow-up duration of 5 years. The participants were divided into two groups: ASD and non-ASD. ASD was defined as clinical ASD rather than radiographic ASD. Various patient and operative variables were compared between the groups. Global and regional radiographic parameters (preoperatively and postoperatively) were also compared between the two groups using plain radiography and MRI. Consequently, univariate and multivariate analyses were conducted to identify the risk factors for ASD occurrence. The receiver operating characteristic (ROC) curve was used to calculate the cutoff values. The mean ± SD age was 67.7 ± 7.2 years at the time of SSF, and there were 62 women (77.5%) enrolled in the study. Thirty patients (37.5%) were in the ASD group and 50 patients (62.5%) were in the non-ASD group. The mean time from the surgery to ASD diagnosis was 34.9 ± 28.2 months in ASD group. Thirteen patients required revision surgery at a mean time of 8.8 ± 7.0 months after ASD occurrence. Multivariate logistic regression analysis demonstrated that preoperative disc wedging angle (OR 1.806, 95% CI 1.255-2.598, p = 0.001), presence of facet tropism (defined as ≥ 10° difference between the facet joint angles of the right and left sides) (OR 5.534, 95% CI 1.528-20.040, p = 0.009), and foraminal stenosis ≥ grade 2 (OR 5.935, 95% CI 1.253-28.117, p = 0.025) were significant risk factors for ASD development. The cutoff value of the preoperative disc wedging angle was calculated to be 2.5° using the ROC curve. Preoperative disc wedging angle ≥ 2.5°, presence of facet tropism, and foraminal stenosis ≥ grade 2 were identified as significant risk factors for ASD development after SSF in patients with DNDLS.

Validation of Roussouly classification in predicting the occurrence of adjacent segment disease after short-level lumbar fusion surgery

BackgroundRecent studies demonstrated that restoring sagittal alignment to the original Roussouly type can remarkably reduce complication rates after adult spinal deformity surgery. However, there is still no data proving the benefit of maintaining ideal Roussouly shape in the lumbar degenerative diseases and its association with the development of adjacent segment disease (ASD). Thus, this study was performed to validate the usefulness of Roussouly classification to predict the occurrence of ASD after lumbar fusion surgery.Materials and MethodsThis study retrospectively reviewed 234 consecutive patients with lumbar degenerative diseases who underwent 1- or 2-level fusion surgery. Demographic and radiographic data were compared between ASD and non-ASD groups. The patients were classified by both “theoretical” [based on pelvic incidence (PI)] and “current” (based on sacral slope) Roussouly types. The patients were defined as “matched” if their “current” shapes matched the “theoretical” types and otherwise as “mismatched”. The logistic regression analysis was performed to identify the factors associated with ASD. Finally, clinical data and spinopelvic parameters of “theoretical” and “current” types were compared.ResultsWith a mean follow-up duration of 70.6 months, evidence of ASD was found in the 68 cases. Postoperatively, ASD group had more “current” shapes classified as type 1 or 2 and fewer as type 3 than the non-ASD group (p < 0.001), but the distribution of “theoretical” types was similar between groups. Moreover, 80.9% (55/68) of patients with ASD were mismatched, while 48.2% (80/166) of patients without ASD were mismatched (p < 0.001). A multivariate analysis identified age [odds ratio (OR) = 1.058)], 2-level fusion (OR = 2.9830), postoperative distal lordosis (DL, OR = 0.949) and mismatched Roussouly type (OR = 4.629) as independent risk factors of ASD. Among the four "theoretical" types, type 2 had the lowest lumbar lordosis, DL, and segmental lordosis. When considering the "current" types, current type 2 was associated with higher rates of 2-level fusion, worse DL, and greater pelvic tilt compared with other current types.ConclusionsDL loss and mismatched Roussouly type were significant risk factors of ASD. To decrease the incidence of ASD, an appropriate value of DL should be achieved to restore sagittal alignment back to the ideal Roussouly type.Level of Evidence: Level 4.

Exploring the incidence and risk factors of reoperation for symptomatic adjacent segment disease following cervical decompression and fusion

Patients with long-term follow-up after cervical decompression and fusion have often been noted to have development of adjacent segment degeneration with a smaller subset of these patients progressing to adjacent segment disease (ASD), which results in the development of new symptomatic radiculopathy or myelopathy referable to a site either directly above or below a prior fused segment. The cause of ASD is multifactorial often involving natural age-related progression of spondylosis, accelerated progression following cervical decompression and fusion, operative technique, and patient-related factors. The effect of age at the time of index cervical decompression and fusion on the need for reoperation for ASD is not fully understood. This study aims to establish underlying risk factors for the development of symptomatic cervical ASD following cervical decompression and fusion requiring reoperation in patients of various age groups. A retrospective database review of patients aged 20 or greater with insurance claims of primary cervical decompression and fusion over the course of 11 years and 10 months (January 01, 2010-October 31, 2022) was conducted using an insurance claims database. The primary outcome was to evaluate the incidence of cervical ASD requiring reoperation amongst patients stratified by age at the time of their primary procedure. Secondary outcomes included an evaluation of various risk factors for ASD following cervical decompression and fusion including surgeon-controlled factors such as the number of levels fused and approach taken, patient cervical pathology including cervical disc disorder and cervical spondylosis, and underlying patient medical comorbidities including osteoporosis and vitamin D deficiency, and substance use. A total of 60,292 patient records were analyzed, where the overall reoperation incidence for symptomatic ASD was 6.57%, peaking at 8.12% among those aged 30 to 39 and decreasing with age. Regression analysis revealed ages lower than 50 years as more predictive for the development of symptomatic ASD requiring reoperation. Multivariate regression analysis identified predictive factors for reoperation, including age, Elixhauser Comorbidity Index (ECI), multiple-level surgery, cervical spondylosis, cervical disc disorder, osteoporosis, and vitamin D deficiency. Notably, these factors had a variable impact across various age groups, as revealed by subgroup analysis. The incidence of reoperation secondary to symptomatic ASD is 6.57%, highest in those aged 30 to 39. The surgical approach had no significant impact on the need for reoperation, but multiple-level fusions posed a consistent risk in the development of symptomatic ASD requiring reoperation. Patient factors like degenerative disc disease, spondylosis, osteoporosis, and vitamin D deficiency were associated, urging further age-specific risk assessment and nonoperative intervention exploration.

The Fate of Pre-Existing L5-S1 Degeneration following Oblique Lumbar Interbody Fusion of L4-L5 and Above

Background: Previous studies have identified various risk factors for adjacent segment disease (ASD) at the L5-S1 level after fusion surgery, including preoperative sagittal imbalance, longer fusion, and preoperative disc degeneration. However, only a few studies have explored the risk factors for ASD at the L5-S1 level after oblique lumbar interbody fusion (OLIF) at the L4-L5 level and above. This study aimed to identify the risk factors for symptomatic ASD at the L5-S1 level in patients with pre-existing degeneration after OLIF at L4-L5 and above. Methods: We retrospectively reviewed the data of patients who underwent OLIF at L4-L5 and above, with a minimum follow-up period of 2 years. Patients with central stenosis or Lee grade 2 or 3 foraminal stenosis at L5-S1 preoperatively were excluded. Patients were divided into ASD and non-ASD groups based on the occurrence of new-onset L5 or S1 radicular pain requiring epidural steroid injection (ESI). The clinical and radiological factors were analyzed. Logistic regression was used to identify the risk factors for ASD of L5-S1. Results: A total of 191 patients with a mean age ± standard deviation of 68.6 ± 8.3 years were included. Thirty-four (21.7%) patients underwent ESI at the L5 root after OLIF. In the logistic regression analyses, severe disc degeneration (OR (95% confidence interval (CI)): 2.65 (1.16–6.09)), the presence of facet effusion (OR (95% CI): 2.55 (1.05–6.23)), and severe paraspinal muscle fatty degeneration (OR (95% CI): 4.47 (1.53–13.05)) were significant risk factors for ASD in L5-S1. Conclusions: In this study, the presence of facet effusion, severe disc degeneration, and severe paraspinal muscle fatty degeneration at the L5-S1 level were associated with the development of ASD at L5-S1 following OLIF at L4-L5 and above. For patients with these conditions, surgeons could consider including L5-S1 in the fusion when considering OLIF at the L4-L5 level and above.

Evaluation of spinopelvic alignment according to Roussouly classification can predict the occurrence of adjacent segment disease after lumbar fusion

Objective: To investigate the correlation of spinopelvic alignment according to Roussouly classification on the occurrence of adjacent segment disease (ASD) in the patients undergoing fusion surgery for lumbar degenerative diseases. Methods: A cross-sectional study. Clinical data of 166 consecutive patients who had undergone lumbar fusion between January 2009 and January 2019 in the Affiliated Changzhou Second People's Hospital of Nanjing Medical University and Affiliated Drum Tower Hospital of Medical School of Nanjing University were retrospectively reviewed. There were 59 males and 107 females, with an average age of (58.6±9.5) years (ranged 41-78 years). Fusion length averagely spanned (1.7±0.7) levels (ranged 1-3 levels). The patients were classified by both "theoretical" (based on pelvic incidence (PI)) and "current"(based on sacral slope (SS)) Roussouly types. The patients were classified as "matched" if their "current" shape matched the "theoretical" type and otherwise as "unmatched". Multivariate logistic regression analysis of the variables recruited from univariate analyses was performed to identify the factors independently associated with the development of ASD after lumbar fusion. Results: The average follow-up duration after initial surgery was (49.2±20.7) months (ranged 25 to 134 months). Thirty (18.1%, 30/166) patients were diagnosed as ASD. Postoperatively, two thirds of the patients who suffered ASD after surgery were unmatched, while 36.8% (50/136) of the patients without ASD had unmatched type. Univariate analyses showed that older age, more fusion levels, float fusion, pre-and postoperative worse spinopelvic alignment, and postoperative unmatched Roussouly type were identified as risk factors of ASD. Multivariate logistic regression analysis identified postoperative Roussouly type mismatch (OR=3.310, 95%CI: 1.282-8.545, P=0.013), old age (OR=1.074, 95%CI: 1.019-1.131, P=0.008) and postoperative SS (OR=0.928, 95%CI: 0.865-0.995, P=0.036) as the independent risk factors of development of ASD after lumbar fusion. Conclusion: A significant association between postoperative sagittal malalignment and occurrence of ASD is detected, the evaluation of sagittal alignment by Roussouly classification could help predict the occurrence of ASD.

Single Surgeon Experience of Adjacent Segment Disease and Related Risk Factors Following Posterior Decompression and Fusion in Lumbar Degenerative Disorders

Background and Aim: This study aims to evaluate the frequency of adjacent segment disease (ASD) and its risk factors following posterior decompression and fusion in lumbar degenerative disorders. Methods and Materials/Patients: This retrospective cohort study was performed by reviewing the records of patients with spinal degeneration disorders who underwent lumbar fusion surgery and needed reoperation from 2013 to 2019. The participants were divided into two groups, including patients with ASD and non-ASD patients, and were compared in terms of age, sex, BMI, smoking, fusion level, surgical indications, follow-up times, laminectomy, cross-link device usage, imaging findings, fusion terminating in L1, L5 and S1, and reoperation. Results: Out of a total of 277 candidates, 181 met the inclusion criteria. In terms of gender distribution, 43.3% of the participants were male and 56.7% were female. The median age was 54 years in the ASD group and 48 years in the non-ASD group. The median follow-up of the patients was six years in the ASD group and five years in the non-ASD group. Forty patients (22.1%) developed ASD during this period. The final analysis showed a significant relationship between age, sex, indication for reoperation, repeated surgery, laminectomy, cross-link device use, imaging findings, and fusion terminating in L1. Conclusion: High body mass index, aging, lumbar spinal canal stenosis, reoperation, laminectomy at the upper fusion unit, cross-link device use, lumbar canal stenosis in imaging, and fusion to L1 vertebrae are considered risk factors for ASD.

Effect of sagittal screw angle and distance of screw apex to superior endplate on adjacent segment disease after posterolateral lumbar fusion: a retrospective study

BackgroundNumerous complications of lumbar fusion surgery have been reported, with adjacent segment disease (ASD) being one of the most important. Few studies describe the effect of sagittal, horizontal screw angles and distance of pedicle screw apex to superior endplate on the incidence of ASD in lumbar spine. The purpose of this retrospective study is to evaluate the hypothesis that unsatisfactory pedicle screw insertion positions would increase the likelihood of ASD.MethodsOutpatients with lumbar spinal stenosis underwent posterolateral lumbar fusion at L4-S1 with a least 2-year follow-up were studied. ASD at L3–L4 was defined as a condition in which intervertebral disk narrowing, posterior vertebral opening, and vertebral slippage progress at the last follow-up in comparison with the postoperative. Independent t test was performed to compare data between two groups; Spearman analysis was performed to analyze the relationship between two continuous variables. Multivariate binary logistic models were performed to identify the independent risk factors of ASD. The receiver operating characteristic (ROC) curve was performed to measure model discrimination and Hosmer–Lemeshow (H–L) test was used to measure calibration. ROC curve evaluated the discrimination ability of sagittal screw angle and distance in predicting incidence of ASD.ResultsPatients in ASD group exhibit higher incidence of osteoporosis, higher Visual analogue scale (VAS), Oswestry disability index (ODI), bigger sagittal screw angle, shorter distance of pedicle screw apex to superior endplate than those in non-ASD group (p < 0.05). VAS, ODI at the last follow-up were positively correlated with Pfirrmann grade of L3–4 disk and sagittal screw angle, while negatively correlated with distance of screw apex to superior endplate (p < 0.05). Multivariate binary logistic model indicated that follow-up time (odds ratio [OR] 1.637, 95% confidence interval [CI] 1.186–2.260), distance of screw apex to superior endplate (OR 0.150, 95% CI 0.067–0.336), sagittal screw angle (OR 2.404, 95% CI 1.608–3.594) were statistically significant. The models showed great discrimination and calibration. The area under the curve of ASD identified by sagittal angle and distance was 0.895 and the cut-off values were 5.500° and 6.250 mm, respectively.ConclusionSagittal screw angle and distance of screw apex to superior endplate were significantly associated with the risk of ASD.

Low lumbar multifidus muscle status and bone mineral density are important risk factors for adjacent segment disease after lumbar fusion: a case–control study

BackgroundThe quantity and quality of the paraspinal muscles are important factors that lead to spinal diseases. However, the role of paraspinal muscles in the pathogenesis of adjacent segment disease (ASD) after lumbar fusion surgery is rarely studied. The purpose of the research is to investigate the relationship between paraspinal muscles and ASD.MethodsThirty-three patients with ASD were included, and 33 controls without ASD were matched according to the basic demographic information. Cross-sectional images of the paraspinal muscles at each intervertebral disk level (L1–S1) before the first operation were analyzed, and the cross-sectional area (CSA) and degree of fat infiltration (FI) of the multifidus (MF) muscle and the erector spinae muscle were compared.ResultsThere was no significant difference in demographic characteristics (P > 0.05) except for the bone mineral density (BMD) (P = 0.037) between the two groups. There were significant differences in the CSA and FI of the lower lumbar multifidus (P < 0.05). The CSA of the MF muscle at L3–L4, FI of the MF muscle at L4–L5 and L5–S1 and BMD were important risk factors for ASD. Among patients who received two-segment fusion for the first time, significant difference was observed in the degree of FI of the MF muscle in the lower lumbar segment (P < 0.05).ConclusionsThe CSA, FI and BMD of the lower lumbar MF muscle were closely related to the occurrence of ASD. The CSA of the MF muscle at L3–L4, the degree of FI of the MF muscle at L4–L5 and L5–S1 and BMD were important risk factors for ASD. The number of fusion segments in the first operation has a certain impact on the above-mentioned conclusions.

Adjacent segment disease after minimally invasive transforaminal lumbar interbody fusion for degenerative lumbar diseases: incidence and risk factors

Study designRetrospective study.ObjectivesTo explore the incidence and risk factors for symptomatic adjacent segment disease (ASD) in patients enveloped in degenerative lumbar diseases after minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).MethodsData were retrospectively analyzed on 744 patients who underwent MIS-TLIF for degenerative lumbar diseases in our hospital from October 2012 to December 2018. The patients were divided into the ASD group and non-ASD (N-ASD) group on the basis of developing ASD at follow-up, and then the incidence of ASD was calculated. Clinical and radiological risk factors were assessed over time to determine their association with ASD by excluding less important factors.ResultsData were missing for 26 patients, while a total of 718 patients were successfully monitored after MIS-TLIF. Of the 718 individuals participated in the study, 34 (4.7%) patients plagued by ASD required surgical intervention. The average onset time of ASD was 62.7 ± 15.1 months. Univariate analysis results shows that age, bone mineral density (BMD), body mass index (BMI), preoperative adjacent intervertebral disc height and preoperative adjacent segment disc degeneration were significantly different between the ASD and N-ASD groups (p < 0.05). The logistic regression analysis results demonstrated that BMD (p = 0.039, OR = 0.986, 95% CI 0.899–1.115), BMI (p = 0.041, OR = 1.119, 95% CI 1.103–2.397), and preoperative adjacent intervertebral disc degeneration (p = 0.023, OR = 1.215, 95% CI 1.015–1.986) may be seen as risk factors for ASD after MIS-TLIF.ConclusionsThe incidence of ASD was about 4.7% in patients suffer from degenerative lumbar diseases after MIS-TLIF. BMD, BMI and preoperative adjacent intervertebral disc degeneration might be the risk factors for the occurrence of ASD after MIS-TLIF. Our research also suggested that patients with lower BMD, higher BMI and disc preoperative adjacent segment disc degeneration were more likely to develop ASD after MIS-TLIF.

Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion with Plate Fixation: A Systematic Review and Meta-Analysis.

Adjacent segment disease (ASD) following anterior cervical discectomy and fusion with plating (ACDF-P) may yield a poor prognosis or reoperation. This review aimed to summarize risk factors for radiographic ASD (RASD) and clinical ASD (CASD) after ACDF-P. Six electronic databases were searched from inception to October 30, 2021. Four reviewers independently screened titles, abstracts, and full-text articles to identify relevant studies. Methodological quality of the included studies was evaluated. Meta-analyses for risk factors were conducted, if possible. Sixteen cohort and 3 case-control studies (3,563 participants) were included. These studies showed low (n = 2), moderate (n = 9), and high (n = 8) risk of bias. One risk factor for RASD was pooled for 2 meta-analyses based on the follow-up period. Four different risk factors for CASD at ≥4 years were pooled for meta-analyses. Limited evidence showed that multi-level fusion, greater asymmetry in total or functional cross-sectional area of the cervical paraspinal muscle, and preoperative degeneration in a greater number of segments were associated with a higher RASD incidence <4 years after ACDF-P. In contrast, no significant risk factors were identified for CASD <4 years after ACDF-P. At ≥4 years after ACDF-P, limited evidence supported that both cephalad and caudal plate-to-disc distances of <5 mm were associated with a higher RASD incidence, and very limited evidence supported that developmental canal stenosis, preoperative RASD, unfused C5-C6 or C6-C7 adjacent segments, use of autogenous bone graft, and spondylosis-related ACDF-P were associated with a higher CASD incidence. Although several risk factors for RASD and CASD development after ACDF-P were identified, the supporting evidence was very limited to limited. Future prospective studies should extend the existing knowledge by more robustly identifying risk factors for RASD and CASD after ACDF-P to inform clinical practice. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

P124. Does simultaneous decompression above a fusion lead to progressive adjacent segment disease requiring revision surgery?

<h3>BACKGROUND CONTEXT</h3> Degenerative spondylolisthesis (DS) is a condition that often requires surgical treatment. This treatment varies based on surgeon preference and the extent of lumbar pathology seen on imaging. There is controversy regarding the surgical management of segments adjacent to the level of DS that require decompression. While it is understood that decompression and fusion of affected levels is necessary, it is unclear how best to treat levels adjacent to the level of DS. Some surgeons will always fuse any additional levels that require decompression while others will decompress adjacent segments without extending the fusion. Each technique has its own theoretical risks, but analysis of adjacent segment disease (ASD) and need for repeat surgery has not been extensively studied. <h3>PURPOSE</h3> The primary aim is to identify the rate of and risk factors related to progression of ASD and the need for revision surgery in patients with surgically treated DS. The secondary aim is to analyze the efficacy of decompressing adjacent levels without fusion. <h3>STUDY DESIGN/SETTING</h3> All patients treated surgically for DS at a tertiary care medical center over a 5-year period were retrospectively reviewed. Patients were divided into two cohorts consisting of those patients who were fused at all decompressed levels versus those who were not fused at all decompressed levels. <h3>PATIENT SAMPLE</h3> Adult patients who had decompression and fusion of affected levels with decompression of adjacent levels and at least 1 year of followup were included. There were 137 such patients identified. <h3>OUTCOME MEASURES</h3> Patient demographics, level(s) of DS at presentation, ASD rates and reoperation rates were measured and analyzed. Rates of ASD were measured based on clinical presentation, radiographic results and/or need for reoperation. <h3>METHODS</h3> Descriptive statistics were used to summarize demographic and comorbidity data. Relative risks were calculated and two proportion z-test was used to compare rates of adverse events in the two surgical cohorts. Odds ratios were calculated for risk factors associated with adverse events. <h3>RESULTS</h3> Of the 137 patients, 86 (63%) were female and 51 (37%) were male. The average followup was 19.9 months. There were 119 (87%) patients with single level DS and 18 (13%) with DS at two adjacent levels. The most common level for DS was L4-5 (100, 73%). Thirty-four patients underwent a multilevel decompression and fusion only at the level of the DS, while 103 had a fusion at all the decompressed levels. Twelve patients (9%) had progression of ASD requiring extension of their construct; 11 of these patients were female (92%), however female sex was not a statistically significant risk factor for ASD (p = 0.06). Of the 12 patients, 3 had DS at L3-4, 9 at L4-5 and 2 at L5-S1. Two patients were decompressed more levels than fused, and 10 were fused at all levels decompressed. Neither level of DS nor surgical technique correlated with increased risk of ASD. <h3>CONCLUSIONS</h3> Progression of ASD requiring revision surgery is a risk after surgery for DS. The data demonstrates that there is no additional risk of ASD if adjacent levels are decompressed without fusion. This is the first study to our knowledge that shows equal efficacy of decompression without fusion of adjacent levels for the treatment of lumbar DS. The researchers will next compare radiographic and patient-reported outcome data between patients treated with decompression of adjacent segments only versus those treated with decompression and fusion of adjacent segments. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Risk factors for early-onset radiographical adjacent segment disease in patients with spondylolytic spondylolisthesis after single-level posterior lumbar interbody fusion

BACKGROUND CONTEXTThe risk factors for radiographical adjacent segment disease (ASD) in patients with degenerative spondylolisthesis have been previously reported. However, there are only few reports on patients with spondylolytic spondylolisthesis who underwent single-level posterior lumbar interbody fusion (PLIF). PURPOSEThe study aimed to investigate the risk factors for radiographical ASD in patients with L5–S1 spondylolytic spondylolisthesis who underwent single-level PLIF. STUDY DESIGN/SETTINGA retrospective study PATIENT SAMPLEThis study retrospectively reviewed 135 consecutive patients (91 men and 44 women) with symptomatic L5–S1 spondylolytic spondylolisthesis who underwent single-level PLIF. OUTCOME MEASURESThe pre- and postoperative (at the final follow-up) spinopelvic parameters, % slip, sacral slope, lumbar lordosis (LL), pelvic tilt, pelvic incidence (PI), PI minus LL (PI − LL), lumbosacral angle, C7 sagittal vertical axis, and thoracic kyphosis were measured using standing radiographs. METHODSRadiographical ASD was defined as disc height loss (>3 mm), increase of posterior angulation (>5°), or progression of spondylolisthesis (>3 mm) between the pre- and postoperative radiographs. Pfirrmann's classification was used to evaluate disc degeneration. The radiographical parameters and changes between the pre- and postoperative values were evaluated and compared for the non-ASD and ASD groups. Binary logistic regression analysis was performed to evaluate the adjusted associations between each potential explanatory variable and ASD development. RESULTSThe radiographical ASD incidence was 11%. Additionally, 60% of the patients with ASD had radiographical ASD at 1 year and all cases of radiographical ASD in this follow-up period occurred within 3 years after the initial surgery. The mean period of ASD occurrence after initial surgery was 21.7 ± 12.6 months. No patients required reoperation for radiographical ASD. Multivariate analysis revealed that a preoperative (odds ratio [OR], 5.9; 95% confidence interval [CI], 1.2–28.9; p=.03) and a postoperative (OR, 6.5; 95% CI, 1.2–34.5; p=.03) PI − LL of ≥15° were risk factors for radiographical ASD. CONCLUSIONSPre- and postoperative PI − LL value mismatch was identified as significant independent risk factors for radiographical ASD in patients with L5–S1 spondylolytic spondylolisthesis. Obtaining larger lordosis at L5–S1 may be the key to preventing radiographical ASD.

Adjacent segment disease following Dynesys stabilization for lumbar disorders: A case series of mid- and long-term follow-ups.

BACKGROUNDRadiologic adjacent segment degeneration (ASDeg) can occur after spinal surgery. Adjacent segment disease (ASDis) is defined as the development of new clinical symptoms corresponding to radiographic changes adjacent to the level of previous spinal surgery. Greater pre-existing ASDeg is generally considered to result in more severe ASDis; nonetheless, whether the ASDeg status before index surgery influences the postoperative risk of revision surgery due to ASDis warrants investigation.AIMTo identify possible risk factors for ASDis and verify the concept that greater preexisting ASDeg leads to more severe ASDis.METHODSData from 212 patients who underwent posterior decompression with Dynesys stabilization from January 2006 to June 2016 were retrospectively analyzed. Patients who underwent surgery for ASDis were categorized as group A (n = 13), whereas those who did not were classified as group B (n = 199). Survival analysis and Cox proportional hazards models were used to compare the modified Pfirrmann grade, University of California-Los Angeles grade, body mass index, number of Dynesys-instrumented levels, and age.RESULTSThe mean time of reoperation was 7.22 (1.65–11.84) years in group A, and the mean follow-up period was 6.09 (0.10–12.76) years in group B. No significant difference in reoperation risk was observed: Modified Pfirrmann grade 3 vs 4 (P = 0.53) or 4 vs 5 (P = 0.46) for the upper adjacent disc, University of California-Los Angeles grade 2 vs 3 for the upper adjacent segment (P = 0.66), age of < 60 vs > 60 years (P = 0.9), body mass index < 25 vs > 25 kg/m2 (P = 0.3), and sex (P = 0.8).CONCLUSIONGreater preexisting upper ASDeg was not associated with a higher rate of reoperation for ASDis after Dynesys surgery. Being overweight tended to increase reoperation risk after Dynesys surgery for ASDis.

Risk factors for adjacent segment disease requiring reoperation after posterior lumbar interbody fusion with screw fixation: focus on paraspinal muscle, facet joint, and disc degeneration.

Adjacent segment disease (ASD) requiring revision surgery is the most serious complication that can occur in patients undergoing posterior lumbar interbody fusion (PLIF) surgery. This study aimed to determine the risk factors for surgical ASD requiring revision surgery after PLIF with screw fixation surgery. We especially focused on paraspinal muscle, facet joint, and disc degeneration. Among the patients who underwent PLIF with screw fixation due to degenerative spinal disease from January 2010 to December 2019, patients who underwent revision surgery for the development of ASD were enrolled. To evaluate the risk factors for surgical ASD, we selected a control group. Each patient in the control group was matched by age, sex, fusion level, number of fused segments, secondary MRI follow-up interval, and follow-up duration with a patient in the surgical ASD group. The radiographic and demographic data were compared between the surgical ASD and control groups. There were statistically significant differences between the two groups in radiological parameters of preoperative facet degeneration, facet effusion, facet angle, and fatty degeneration of the multifidus muscle. Multivariable logistic regression analysis revealed that preoperative facet effusion (odds ratio [OR] 6.48), preoperative facet angle (OR 1.24), and progression of fatty degeneration in the multifidus muscle (OR 1.07) were significant risk factors for surgical ASD. Preexisting high-grade adjacent facet effusion, sagittally oriented facet joint angle, and progressive fatty degeneration of the multifidus muscle are associated with the development of surgical ASD after PLIF surgery.

Incidence and Risk Factors for Adjacent Segment Disease After Transforaminal Lumbar Interbody Fusion in Patients with Lumbar Degenerative Diseases.

PurposeTo explore the incidence and risk factors for adjacent segment disease (ASD) in patients with lumbar degenerative diseases after transforaminal lumbar interbody fusion (TLIF).Patients and MethodsThe clinical data of 1258 patients who underwent transforaminal lumbar interbody fusion (TLIF) for lumbar degenerative diseases in our hospital from January 2011 to December 2017 were retrospectively analyzed. Patients were divided into the ASD group and non-ASD (N-ASD) group, and the incidence of ASD was calculated. We compared age, BMI, comorbidities, surgery-related parameters, and imaging parameters before surgery between the two groups and used univariate analysis and logistic regression analysis to explore the risk factors for ASD.ResultsAmong the 1258 patients who underwent TLIF due to lumbar degenerative diseases, 65 patients developed ASD and received surgical treatment for it, for an incidence of 5.2%. The average onset time of ASD was 68.3±25.1 (20–123) months. Univariate analysis showed that BMI, hypertension, preoperative adjacent segment disc degeneration and preoperative adjacent intervertebral disc height were significantly different between the ASD and N-ASD groups (P< 0.05). Incorporating the above indicators into the logistic regression model, the results showed that BMI and preoperative adjacent intervertebral disc degeneration were risk factors for ASD after TLIF.ConclusionThe incidence of ASD after TLIF in patients with lumbar degenerative disease is approximately 5.2%. High BMI and preoperative adjacent segment disc degeneration are risk factors for ASD after TLIF.

Effect of segmental lordosis on early-onset adjacent-segment disease after posterior lumbar interbody fusion.

Although several reports have described adjacent-segment disease (ASD) after posterior lumbar interbody fusion (PLIF), there have been only a few reports focusing on early-onset ASD occurring within 3 years after primary PLIF. The purpose of this study was to investigate the prevalence and postoperative pathologies of early-onset ASD and its relation with radiological parameters such as segmental lordosis (SL). The authors reviewed a total of 256 patients who underwent single-segment PLIF at L4-5 for degenerative lumbar spondylolisthesis (DLS) and were followed up for at least 5 years. The definition of ASD was a symptomatic condition requiring an additional operation at the adjacent fusion segment in patients who had undergone PLIF. ASD occurring within 3 years after primary PLIF was categorized as early-onset ASD. As a control group, 54 age- and sex-matched patients who had not suffered from ASD for more than 10 years were selected from this series. There were 42 patients with ASD at the final follow-up. ASD prevalence rates at 3, 5, and 10 years postoperatively and at the final follow-up were 5.0%, 8.2%, 14.1%, and 16.4%, respectively. With respect to ASD pathologies, lumbar disc herniation (LDH) was significantly more common in early-onset ASD, while lumbar spinal stenosis and DLS occurred more frequently in late-onset ASD. Significant differences were detected in the overall postoperative range of motion (ROM) and in the changes in ROM (ΔROM) at L3-4 (the cranial adjacent fusion segment) and changes in SL (ΔSL) at L4-5 (the fused segment), while there were no significant differences in other pre- and postoperative parameters. In stepwise logistic regression analysis, ΔSL was identified as an independent variable (p = 0.008) that demonstrated significant differences, especially in early-onset ASD (control 1.1° vs overall ASD -2.4°, p = 0.002; control 1.1° vs early-onset ASD -6.6°, p = 0.00004). The study results indicated that LDH was significantly more common as a pathology in early-onset ASD and that ΔSL was a major risk factor for ASD, especially early-onset ASD.

P53. Clinical risk factors for adjacent segment disease following lumbar spine fusion surgeries: A systematic review and meta-analysis

BACKGROUND CONTEXT Adjacent segment disease (ASD) is a possible complication following lumbar surgeries, particularly lumbar fusion. PURPOSE To investigate the clinical risk factors associated with developing radiological and/or clinical ASD following lumbar fusion. STUDY DESIGN/SETTING Systematic review and meta-analysis. PATIENT SAMPLE Adult patients undergoing lumbar fusion. OUTCOME MEASURES Clinical risk factors associated with the development of ASD. METHODS We performed a comprehensive literature search to find the relevant studies using PubMed, Embase, Medline, Scopus, and the Cochrane library databases from the beginning to December 2019. The titles and abstracts were used for initial screening, followed by a full-text review. The methodological index for non‐randomized studies (MINORS) criteria were used to evaluate the methodological quality of the included studies. A meta-analysis was conducted to calculate the odds ratio (OR) with the 95% confidence interval (CI) for dichotomous variables and mean difference (MD) with 95% CI for continuous variables. Both fixed and random-effects models were used to pool the data according to the observed heterogeneity. RESULTS Thirty-five studies were included in the final qualitative analysis. Twenty-two of these studies were included in the risk factors meta-analyses. The mean quality score of the included studies was 12.4±1.9 (range, 8-16) points, based on the MINORS criteria. The level of evidence was low for many risk factors. Overall, 1,266 (17.2%) patients acquired ASD following lumbar fusion, and 6108 (82.8%) patients did not develop ASD, within a follow-up ranging between 20.5 - 165.6 months. Four clinical variables were found to have statistically significant risk factors for ASD, including higher preoperative body mass index (BMI) (mean difference [MD] = 1.97 kg/m2; 95% confidence interval [CI] = 1.49, 2.45; P CONCLUSIONS High preoperative BMI, floating fusion, superior facet joint violation, and decompression outside fusion construct are associated with a significant risk of developing ASD in patients undergoing lumbar fusion. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Demographic, Surgical, and Radiographic Risk Factors for Symptomatic Adjacent Segment Disease After Lumbar Fusion: A Systematic Review and Meta-Analysis.

Although multiple studies have investigated risk factors for symptomatic adjacent segment disease (ASD) after lumbar fusion, their findings were diverse and inconsistent. This review aimed to summarize risk factors for ASD in order to guide the management of ASD and future research. Six electronic databases were systematically searched from inception to December 2019. Two reviewers independently screened titles, abstracts, and full-text articles to identify studies investigating risk factors for ASD after lumbar fusion in humans. The methodological quality of the included studies and the strength of evidence regarding risk factors were evaluated. Sixteen studies involving 3,553 patients were included. Meta-analyses revealed that high body mass index, facet joint violation, anterior shift of the preoperative and postoperative lumbosacral sagittal plumb line, decreased preoperative and postoperative lumbar lordosis, preoperative adjacent disc degeneration, decreased preoperative adjacent disc height, increased postoperative lumbopelvic mismatch, postoperative pelvic incidence, and postoperative pelvic tilt were significantly related to ASD. This meta-analysis addressed the limitations of prior reviews and summarized evidence with regard to risk factors for ASD following lumbar fusion. Future prospective studies should investigate whether modification of these risk factors can reduce the ASD development. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A comprehensive approach for the validation of lumbar spine finite element models investigating post-fusion adjacent segment effects

Spinal fusion surgery is usually followed by accelerated degenerative changes in the unfused segments above and below the treated segment(s), i.e., adjacent segment disease (ASD). While a number of risk factors for ASD have been suggested, its exact pathogenesis remains to be identified. Finite element (FE) models are indispensable tools to investigate mechanical effects of fusion surgeries on post-fusion changes in the adjacent segment kinematics and kinetics. Existing modeling studies validate only their intact FE model against in vitro data and subsequently simulate post-fusion in vivo conditions. The present study provides a novel approach for the comprehensive validation of a lumbar (T12-S1) FE model in post-fusion conditions. Sixteen simulated fusion surgeries, performed on cadaveric specimens using various testing and loading conditions, were modeled by this FE model. Predictions for adjacent segment range of motion (RoM) and intradiscal pressure (IDP) were compared with those obtained from the corresponding in vitro tests. Overall, 70% of the predicted adjacent segment RoMs were within the range of in vitro data for both intact and post-fusion conditions. Correlation (r) values between model and in vitro findings for the adjacent segment RoMs were positive and greater than 0.84. Most of the predicted IDPs were, however, out of the narrow range of in vitro IDPs at the adjacent segments but with great positive correlations (r ≥ 0.89). FE modeling studies investigating the effect of fusion surgery on in vivo adjacent segment biomechanics are encouraged to use post-surgery in vitro data to validate their FE model.