Revision Surgery For Adjacent Segment Disease Research Articles

Musculoskeletal biomechanics of patients with or without adjacent segment degeneration after spinal fusion

Study designA retrospective, single center, case-control study was performed.ObjectiveThe present study employed patient-specific biomechanical modeling to find potential biomechanical differences after spinal fusion at L4/5 in patients with and without subsequent development of adjacent segment disease (ASD).MethodsThe study population comprised patients who underwent primary spinal fusion at L4/5 and were either asymptomatic during > 4 years of follow-up (CTRL; n = 18) or underwent revision surgery for ASD at L3/4 (n = 20). Landmarks were annotated on preoperative and follow-up lateral radiographs, and specific musculoskeletal models were created using a custom-built modeling pipeline. Simulated spinal muscle activation and lumbar intervertebral shear loads in unfused segments were analyzed in upright standing and forward flexion. Differences between the pre- and postoperative conditions were computed for each patient.ResultsThe average postoperative muscle activity in the upright standing posture was 88.4% of the preoperative activity in the CTRL group (p < 0.0001), but did not significantly change from pre- to postoperatively in the ASD group (98.0%). The average shear load magnitude at the epifusional joint L3/4 during upright standing increased from pre- to postoperatively in the ASD group (+ 3.9 N, +/− 17.4 (n = 18)), but decreased in the CTRL group (− 4.6 N, +/− 23.3 (n = 20); p < 0.001).ConclusionPatient-specific biomechanical simulation revealed that spinal fusion surgery resulted in greater shear load magnitude and muscle activation and therefore greater forces at the epifusional segment in those with ASD compared with those without ASD. This is a first report of patient-specific disc load and muscle force calculation with predictive merits for ASD.

Long-segment posterior cervical decompression and fusion: does caudal level affect revision rate?

Posterior cervical decompression and fusion (PCDF) is a commonly performed procedure to address cervical myelopathy. A significant number of these patients require revision surgery for adjacent-segment disease (ASD) or pseudarthrosis. Currently, there is no consensus among spine surgeons on the inclusion of proximal thoracic spine instrumentation. This study investigates the benefits of thoracic extension in long-segment cervical fusions and the potential drawbacks. The authors compare outcomes in long-segment subaxial cervical fusion for degenerative cervical myelopathy with caudal vertebral levels of C6, C7, and T1. A retrospective analysis identified 369 patients who underwent PCDF. Patients were grouped by caudal fusion level. Reoperation rates for ASD and pseudarthrosis, infection, and blood loss were examined. Data were analyzed with chi-square, 1-way ANOVA, and logistic regression. The total reoperation rate for symptomatic pseudarthrosis or ASD was 4.8%. Reoperation rates, although not significant, were lower in the C3-6 group (2.6%, vs 8.3% for C3-7 and 3.8% for C3-T1; p = 0.129). Similarly, rates of infection were lower in the shorter-segment fusion without achieving statistical significance (2.6% for C3-6, vs 5.6% for C3-7 and 5.5% for C3-T1; p = 0.573). The mean blood loss was documented as 104, 125, and 224 mL for groups 1, 2, and 3, respectively (p < 0.001). Given the lack of statistical difference in reoperation rates for long-segment cervical fusions ending at C6, C7, or T1, shorter fusions in high-risk surgical candidates or elderly patients may be performed without higher rates of reoperation.

Implant Preservation versus Implant Replacement in Revision Surgery for Adjacent Segment Disease After Thoracolumbar Instrumentation: A Retrospective Study of 43 Patients

To evaluate the mechanical properties of a new connector rod aiming to preserve implants in revision surgery (RS) for adjacent segment disease, a problematic complication of instrumented spinal fusion, and to assess its clinical applicability. The mechanical properties of the connector-rod construct (implant preservation) and traditional rod construct (implant replacement) were evaluated and compared. Forty-three patients underwent RS for adjacent segment disease in the thoracolumbar spine with implant preservation or replacement, and radiological and clinical outcomes were assessed. Mechanical properties in group A were comparable to those in group B. Total mean time from prior surgery to RS was 6.86 ± 1.08 years. Surgical time and blood loss values of group A were 40.14% and 29.29% statistically significantly smaller than values of group B. In group B, 12% (3/25) of patients developed surgical site infections. In both groups, the visual analog scale leg score decreased significantly after RS. Early postoperative (at 1-month and 3-month follow-up) Oswestry Disability Index and visual analog scale back scores of group A were significantly lower than those of group B; the difference in the visual analog scale back score between groups was significant until the 6-month follow-up. No implant failures occurred, and spinal fusion was achieved in all cases. The connector rod is considered safe and can reduce the surgical time, blood loss, risk of complications, and medical costs. Better early postoperative clinical outcomes can be achieved with the rod owing to less surgical trauma.

Risk factor analysis of adjacent segment disease requiring surgery after short lumbar fusion: the influence of rheumatoid arthritis

Background ContextThe influence of rheumatoid arthritis (RA) on the lumbar spine has received relatively little attention compared with cervical spine, and few studies have been conducted for adjacent segment disease (ASD) after lumbar fusion in patients with RA. PurposeThe present study aims to determine the incidence of ASD requiring surgery (ASDrS) after short lumbar fusion and to evaluate risk factors for ASDrS, including RA. Study DesignThis is a retrospective cohort study. Patient SampleThe present study included 479 patients who underwent lumbar spinal fusion of three or fewer levels, with the mean follow-up period of 51.2 (12–132) months. Outcome MeasuresThe development of ASD and consequent revision surgery were reviewed using follow-up data. MethodsThe ASDrS-free survival rate of adjacent segments was calculated through Kaplan-Meier method. The log-rank test and Cox regression analysis were used to evaluate risk factors comprising RA, age, gender, obesity, osteoporosis, diabetes, smoking, surgical method, and the number of fusion segments. ResultsAfter short lumbar fusion, revision surgery for ASD was performed in 37 patients (7.7%). Kaplan-Meier analysis predicted that the ASDrS-free survival rate of adjacent segments was 97.8% at 3 years, 92.7% at 5 years, and 86.8% at 7 years. In risk factor analysis, patients with RA showed a 4.5 times higher risk of ASDrS than patients without RA (p<.001), and patients with three-segment fusion showed a 2.7 times higher risk than patients with one- or two-segment fusion (p=.005). ConclusionsAdjacent segment disease requiring surgery was predicted in 13.2% of patients at 7 years after short lumbar fusion. Rheumatoid arthritis and the number of fusion segments were confirmed as risk factors.

A study on the clinical outcomes of patients with revision surgery for adjacent segment disease after 10-year’s anterior cervical spine surgery

BackgroundThe purpose of this study was to investigate the clinical outcomes of anterior cervical discectomy and fusion (ACDF) or anterior cervical corpectomy and fusion (ACCF) as a revision surgery for adjacent segment disease (ASD) after primary surgery.MethodsThere were 35 patients who underwent anterior cervical spine surgery for symptomatic recurrent radicular or myelopathic symptoms from ASD. According to the ASD involved levels superior or inferior to the previous operated level, patients were divided into two groups: superior and inferior groups. The patients were also grouped into ACDF and ACCF groups by who received ACDF or ACCF as revision surgery for ASD. Clinical evaluations were performed preoperatively and repeated at 2 years after operation.ResultsIn this study, a total of 35 patients with a minimum of 2 years of follow-up data were available for analysis. There were 20 patients in the superior group and 15 patients in the inferior group according to the ASD developed at levels. Of these 35 patients, according to the treatment method, 12 patients were in the ACCF group and 23 patients were in the ACDF group. The Japanese Orthopaedic Association (JOA), Neck Disability Index (NDI), and visual analogue scale (VAS) on arm pain and neck pain scores demonstrated significant improvement compared to the preoperative scores in both groups (superior and inferior groups or ACDF and ACCF groups) (P < 0.05). However, there was no difference between the two groups (superior and inferior groups or ACDF and ACCF groups) (P > 0.05).ConclusionsAccording to our study, both superior and inferior adjacent-level groups together with ACDF and ACCF groups maintained favorable clinical results on patients who underwent one-level ACDF for symptomatic new radicular or myelopathic symptoms.

Post-traumatic lower cervical spine instability: Arthrodesis clinical and radiological outcomes at 5 years

BackgroundAnterior cervical fusion is widely used to treat spinal injuries. Radiological evidence of disc abnormalities may develop on either side of the fused segment, raising concern about the potential for inducing adjacent-segment disease. Here, we report the long-term clinical, functional, and radiological outcomes after anterior cervical fusion. HypothesisAnterior cervical fusion influences the development of adjacent-segment disease. Materials and methodsIn a retrospective study, 15 patients aged 17 to 50years were re-evaluated more than 5years after anterior spinal fusion to treat post-traumatic cervical-spine instability. We used the Neck Disability Index (NDI) to assess function. Static and dynamic radiographs of the cervical spine were obtained. ResultsNDI values indicated good clinical and functional outcomes, and fusion was achieved consistently. Adjacent-segment disease was a consistent finding at last follow-up but induced no neurological manifestations. Complete fusion of a level adjacent to the treated level was noted in 2 patients. Revision surgery for adjacent-segment disease was not required in any patient. ConclusionThe causative factors of adjacent-segment disease are controversial. Disc degeneration is a normal manifestation of the ageing process. Nevertheless, disc disease is more prevalent at levels adjacent to interbody fusion than in the normal population, suggesting accelerated disc degeneration due to increased loading of the adjacent levels. Furthermore, lesions that are missed during the pre-operative work-up may play a role, as the available investigations do not always have high negative predictive values. Level of evidenceLevel IV, retrospective study.

Cost per quality-adjusted life year gained of laminectomy and extension of instrumented fusion for adjacent-segment disease: defining the value of surgical intervention

Over the past decade, there has been a dramatic increase in the number of spinal fusions performed in the US and a corresponding increase in the incidence of adjacent-segment disease (ASD). Surgical management of symptomatic ASD consists of decompression of neural elements and extension of fusion. It has been shown to have favorable long-term outcomes, but the cost-effectiveness remains unclear. In this study, the authors set out to assess the cost-effectiveness of revision surgery in the treatment of ASD over a 2-year period. Fifty patients undergoing neural decompression and extension of fusion construct for ASD-associated back and leg pain were included in the study. Two-year total back-related medical resource utilization, missed work, and health state values (quality-adjusted life years [QALYs], calculated from the EQ-5D with US valuation) were assessed. Two-year resource use was multiplied by unit costs based on Medicare national allowable payment amounts (direct cost), and patient and caregiver workday losses were multiplied by the self-reported gross-of-tax wage rate (indirect cost). Mean total 2-year cost per QALY gained after revision surgery was assessed. The mean (± SD) interval between prior fusion and revision surgery for ASD was 3.07 ± 2.02 years. A mean cumulative 2-year gain of 0.76 QALYs was observed after revision surgery. The mean total 2-year cost of extension of fusion constructs was $47,846 ± $32,712 (surgery cost: $24,063 ± $300; outpatient resource utilization cost: $4175 ± $3368; indirect cost: $19,607 ± $32,187). Revision decompression and extension of fusion was associated with a mean 2-year cost per QALY gained of $62,955. In the authors' practice, revision decompression and extension of fusion provided a significant gain in health state utility for patients with symptomatic ASD, with a 2-year cost per QALY gained of $62,995. When indicated, revision surgery for ASD is a valuable treatment option for patients experiencing back and leg pain secondary to ASD. The findings provide a value measure of surgery that can be compared with future cost-per-QALY-gained studies of medical management or alternative surgical approaches.

Preoperative Zung Depression Scale predicts outcome after revision lumbar surgery for adjacent segment disease, recurrent stenosis, and pseudarthrosis

Persistent back pain and leg pain after index surgery is distressing to patients and spinal surgeons. Revision surgical treatment is technically challenging and has been reported to yield unpredictable outcomes. Recently, affective disorders, such as depression and anxiety, have been considered potential predictors of surgical outcomes across many disease states of chronic pain. There remains a paucity of studies assessing the predictive value of baseline depression on outcomes in the setting of revision spine surgery. To assess the predictive value of preoperative depression on 2-year postoperative outcome after revision lumbar surgery for symptomatic pseudarthrosis, adjacent segment disease (ASD), and same-level recurrent stenosis. Retrospective cohort study. One hundred fifty patients undergoing revision surgery for symptomatic ASD, pseudarthrosis, and same-level recurrent stenosis. Patient-reported outcome measures were assessed using an outcomes questionnaire that included questions on health-state values (EQ-5D), disability (Oswestry Disability Index [ODI]), pain (visual analog scale), depression (Zung Self-Rating Depression Scale), and 12-Item Short Form Health Survey physical and mental component scores. One hundred fifty patients undergoing revision neural decompression and instrumented fusion for ASD (n=50), pseudarthrosis (n=47), or same-level recurrent stenosis (n=53) were included in this study. Preoperative Zung Self-Reported Depression Scale score was assessed for all patients. Preoperative and 2-year postoperative visual analog scale for back pain and leg pain scores and ODI were assessed. The association between preoperative Zung Depression Scale score and 2-year improvement in disability was assessed via multivariate regression analysis. Compared to preoperative status, VAS-BP was significantly improved 2 years after surgery for ASD (8.72±1.85 vs. 3.92±2.84, p=.001), pseudoarthrosis (7.31±0.81 vs. 5.06±2.64, p=.001), and same-level recurrent stenosis (9.28±1.00 vs. 5.00±2.94, p=.001). Two-year ODI was also significantly improved after surgery for ASD (28.72±9.64 vs. 18.48±11.31, p=.001), pseudoarthrosis (29.74±5.35 vs. 25.42±6.00, p=.001), and same-level recurrent stenosis (36.01±6.00 vs. 21.75±12.07, p=.001). Independent of age, BMI, symptom duration, smoking, comorbidities, and level of preoperative pain and disability, increasing preoperative Zung depression score was significantly associated with less 2-year improvement in disability (ODI) after revision surgery for ASD, pseudoarthrosis, and recurrent stenosis. Our study suggests that the extent of preoperative depression is an independent predictor of functional outcome after revision lumbar surgery for ASD, pseudoarthrosis, and recurrent stenosis. Future comparative effectiveness studies assessing outcomes after revision lumbar surgery should account for depression as a potential confounder. The Zung depression questionnaire may help risk stratify patients presenting for revision lumbar surgery.