Proximal Adjacent Segment Disease Research Articles

C2 versus C3 or C4 as the upper instrumented vertebra for long-segment cervical fusions: a systematic review and meta-analysis.

Selecting C2 versus C3 or C4 (i.e., C3/C4) as the rostral anchoring level in long-segment cervical fusions is a common clinical conundrum. The data regarding proximal failure in long constructs of the cervical spine is scarce. The objective of this study was to systematically review the published literature and perform a meta-analysis of the incidence for proximal adjacent-segment disease (ASD) in the context of long cervical fusions and cervicothoracic fusions ending in C2 versus those ending in the subaxial spine (C3 or C4). Using the PRISMA guidelines, the authors performed a search of the PubMed/MEDLINE, Embase/Ovid, and Cochrane Central databases to identify all full-text articles in the English-language literature with the following inclusion criteria: 1) studies including patients with the upper instrumented vertebra (UIV) at C2 versus C3/C4; 2) patients undergoing ≥ 3-level posterior cervical fusion; and 3) indication for surgery of degenerative disc disease, cervical spondylotic myelopathy, or cervical deformity. Studies that were not published in the English language, case reports, review articles, letters to the editor, and meeting abstracts were excluded. A meta-analysis was conducted using a fixed-effects model when I2 values were below 70%. Conversely, when I2 values were equal to or greater than 70%, a random-effects model was used. A funnel plot was used to assess the presence of publication bias. Seven studies consisting of 1215 patients were included in the meta-analysis. There were 403 (32.8%) patients in the C2 UIV group and 812 (67.2%) patients in the C3/C4 UIV group. When the 7 studies were analyzed, the overall rate of reoperation was comparable between the C2 (9.2%) and C3/C4 (9.4%) UIV groups (p = 0.93) but the rate of surgical ASD due to proximal pathology was 1.2% and 3%, respectively (OR 0.36, 95% CI 0.15-0.86; p = 0.02). When comparing between groups, no statistical difference was found regarding the rate of reoperation due to distal pathology or surgical infection. Long-segment cervical or cervicothoracic constructs that anchor into C2 may have similar complication rates but lower revision rates for proximal ASD than constructs that anchor into the subaxial spine.

Retro-odontoid pseudotumor concomitant with proximal adjacent cervical spondylotic myelopathy after multilevel anterior cervical discectomy and fusion.

Introduction and importanceAdjacent cervical spondylotic myelopathy (CSM) following anterior cervical discectomy and fusion (ACDF) presenting as a retro-odontoid pseudotumor (ROP) is uncommon. This consequence adversely affects hand function, causes gait imbalance and results in other disabilities for the patient. This report describes the successful surgical treatment of a patient with ROP associated with adjacent CSM following multilevel ACDF of the subaxial cervical vertebrae by performing posterior cervical decompression and fusion.Case presentationA 60-year-old-male presented with progressive, disabling cervical myelopathy. He had undergone ACDF C3-C7 for treatment of CSM 16 years ago and his symptoms had fully resolved. Magnetic resonance imaging (MRI) revealed severe cervical spinal cord compression caused by a retro-odontoid mass at the C1-C2 level with upper adjacent segment disease (ASD) of C1-C3. The patient received C1-C3 posterior cervical spinal fusion by C1 lateral mass C2 and C3 pedicle screw fixation and C1-C3 laminectomy. After the surgery, he was able to ambulate independently and the myelopathic symptoms were significantly improved at the 6 months follow-up.Clinical discussionRetro-odontoid pseudotumor concomitant with proximal ASD following ACDF is a rare occurrence. Both diagnosis and surgical management are challenging.ConclusionsPosterior cervical decompression and fusion of C1-C3 is an effective option for treatment of severe cervical spinal cord compression by a retro-odontoid mass at the C1-C2 level combined with ASD after ACDF.

Is Adjacent Segment Disease More Frequent in Proximal Levels in Comparison with Distal Levels? Based on Radiological Data of at Least 2 Years Follow Up with More than 2 Level Thoracolumbar Fusions.

ObjectiveThe purpose of this retrospective study was to determine which of the proximal adjacent segment disease (ASD) and distal ASD was more prevalent and what parameters is more related to ASD in proximal levels and distal levels after more than 2 levels fusions. MethodsThe medical records were reviewed retrospectively for 856 cases. A total of 66 cases of ASD were enrolled. On preop magnetic resonance imaging, disc degeneration was measured at the upper and lower parts of surgically treated levels and confirmed by the commonly used Pfirrmann grade. Segmental flexibility in sagittal plane was embodied in segment range of motion (ROM) obtained through flexion and extension X-ray before surgery. Coronal angle was recorded as methods Cobb’s angle including fusion levels preoperatively. For the comparison of categorical variables between two independent groups, the chi-square test and Fisher exact test were performed. ResultsProximal ASD and distal ASD were 37/856 (4.32%) and 29/856 (3.39%), respectively. The incidence of proximal ASD was relatively high but insignificant differences. In comparison between ASD group and non ASD group, proximal Pfirmman was higher in proximal ASD and distal Pfirmman was higher in distal ASD group (p=0.005, p<0.008, respectively). However, in the ROM, proximal ROM was higher in proximal ASD, but distal ROM was not different between the two groups (p<0.0001, p=0.995, respectively). Coronal angle was not quite different in both groups (p=0.846). ConclusionIn spite of higher frequency in ASD in proximal level in spinal fusion, it is not clear that incidence of ASD in proximal level is not higher than that of distal ASD group in more than 2 level thoracolumbar fusions. Not only Pfirrmann grade but also proximal segmental ROM is risk factor for predicting the occurrence of ASD in patients more than 2 level of thoracolumbar spine fusion operation excluding L5S1.

262. Do large increases in disc space height have consequences after ACDF?

BACKGROUND CONTEXT During anterior cervical discectomy and fusion (ACDF), distraction of the disc space is used to assist with decompression and graft insertion. In patients with significant preoperative disc space collapse, there may be a large increase in disc space height postoperatively after graft insertion. There are concerns that this acute increase may increase the stresses across the graft-endplate interface and may lead to subsidence or affect other radiographic or clinical outcomes. PURPOSE The aim of the present study was therefore to characterize the difference in preoperative and postoperative disc space height, and to determine the association of an increased change in disc space height with clinical and radiographic outcomes following ACDF. STUDY DESIGN/SETTING Retrospective cohort analysis. PATIENT SAMPLE Analysis was performed on patients who underwent a single-level ACDF by one of two senior spine surgeons between 2008 and 2015 for cervical radiculopathy and/or myelopathy, with a minimum of 6 months of clinical and radiographic follow-up. OUTCOME MEASURES Radiographs were reviewed preoperatively and immediately postoperatively, and at final follow up. Disc height was measured as the anterior vertebral distance (AVD), mid-vertebral distance (MVD), and posterior vertebral distance (PVD) on preoperative and immediate postoperative radiographs. Sagittal parameters were also measured, and included C2-C7 lordosis, T1 angle, fusion segment lordosis, sagittal vertical axis (SVA), proximal and distal adjacent segment lordosis. Visual Analogue Scale (VAS) neck, VAS arm, and Neck Disability Index (NDI) scores were collected at each postoperative clinical visit. The rates of adjacent segment disease, reoperation, successful fusion and subsidence (postoperative disc space collapse >2mm) were determined. METHODS Radiographs were reviewed preoperatively and immediately postoperatively, and at final follow-up, along with patient reported outcomes. Multivariate regressions were used to control for baseline patient characteristics. RESULTS A total of 120 patients met inclusion criteria. Mean follow-up length was 29 months, and mean age was 46.9 years, mean BMI was 28.4, and 45.4% of patients were female. Increased preoperative to postoperative disc height change in all regions was associated with development of distal adjacent segment disease (AVD OR 1.89, p=0.013; MVD OR 1.75, p=0.043; PVD OR 2.07, p=0.014), but not proximal adjacent segment disease. increased change in AVD was associated with a greater change in preoperative to postoperative C2-C7 lordosis, fusion segment lordosis and proximal segment lordosis. Increased change in AVD was also associated with increased preoperative to final change in lordosis. No other associations were found between preoperative to postoperative difference in AVD, MVD or PVD and preoperative, immediate postoperative or final sagittal parameters. Additionally, no associations were found between preoperative to postoperative disc height change and any clinical outcomes. Rates of reoperation, fusion, and subsidence did not vary based on preoperative to postoperative disc height change. CONCLUSIONS This study found that a greater difference in preoperative to postoperative disc space height following ACDF was associated with the development of distal adjacent segment degeneration; however, it was not associated with most radiographic outcomes, or any patient-reported outcomes. Large changes in disc space height may not be benign, and further study is needed to characterize the etiology of ASD associated with these changes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Posterior elements disruption with hybrid constructs in AIS patients: is there an impact on proximal junctional kyphosis?

Proximal junctional kyphosis (PJK) is a frequent proximal adjacent segment disease following spinal fusion in adolescent idiopathic scoliosis (AIS) and its rate has been estimated to 28% in the literature. The etiology is multifactorial, and risk factors associated with PJK are controversial. The aim of this study was to demonstrate that the disruption of muscular and bony tissue above the upper instrumented vertebra (UIV) during surgery does not increase the rate of PJK in patients undergoing posterior fusion for adolescent idiopathic scoliosis. 50 patients with AIS operated between June 2014 and January 2016 were included. Every patient underwent a long posterior spine arthrodesis with a hybrid construct (proximal lamino-laminar claw, thoracic sublaminar bands and lumbar screws). The dissection of posterior elements above the UIV was necessary for the placement of proximal anchors. Radiographic analysis including proximal junctional angle, spino-pelvic parameters (cervical lordosis, thoracic kyphosis TK, lumbar lordosis, pelvic incidence, pelvic tilt, sacral slope) and sagittal vertical axis were collected preoperatively and postoperatively at the last control. The numbers of fused levels, locations of upper instrumented vertebra, locations of lower instrumented vertebra, length of fusion segments were also recorded. Multiple odd ratios and other statistical analysis were performed to evaluate the relation between PJK and the potential risk factors. There were 43 females and 7 males with a mean age of 14.8years at surgery. PJK occurred in 5 out of 50 cases with an incidence of 10%. The mean follow-up was 18months. There was no significant difference in gender (OR 1.36, p = 0.8), decrease of TK (OR 1.63, p = 0 0.69), location of UIV (OR 2.25, p = 0.4), LIV (OR 2, p = 0.55), and SVA change (OR 1.63, p = 0.46). The disruption of ligamentous and bony tissue proximal to the UIV during the surgery does not increase the rate of PJK. Level of evidence IV.

Correlation of Adjacent Segmental Disease with Tilt Angles of the Upper and Lower Instrumented Vertebra in the Degenerative Lumbar Scoliosis

Study Design: Retrospective study. Objectives: To evaluate the correlation of adjacent segmental disease with tilt angles of the upper and lower instrumented vertebra after instrumented posterolateral fusion for degenerative lumbar scoliosis. Summary of Literature Review: There has been no study of radiologic measurement and decision of fusion level using the angle of pedicle screws inserted for treatment of degenerative lumbar scoliosis. Materials and Methods: From 2004 to 2008, 74 patients that underwent decompression and posterolateral fusion for degenerative lumbar scoliosis were included in this study. In all cases, instrumentation and posterolateral fusion were both performed. The sex ratio was 31:43, the mean age was 68.7 years and the mean follow up duration was 37.4 months. The angle between each upper end plate of the upper vertebral body and lower end plate of the lower vertebral body of the fusion, and the line parallel to the axis of the sagittal line of vertebrae was each defined as UIV-a and LIV-b. The correlation of development of adjacent segment disease and UIV-a, and LIV-b angle was investigated. Results: Sum of the absolute value of UIV-a and LIV-b had a statistically significant positive correlation with that of adjacent segment disease. Also, UIV-a alone, had a statistically positive correlation with the development of proximal adjacent segment disease. Conclusions: Since it is proven that adjacent segment disease has positive correlation with the sum of the absolute value of UIV-a and LIV-b, the extent of fusion should be adjusted to make the line parallel to the line perpendicular to the sagittal surface.

Selection of proximal fusion level for adult degenerative lumbar scoliosis

There is controversy regarding the appropriate proximal fusion level for adult degenerative scoliosis. Ideally, the horizontal vertebra is chosen for the upper instrumented vertebra to create a balanced spine. Fusion to T10 is recommended to prevent junctional problems at the proximal adjacent segment. The purpose of this retrospective study was to determine the optimal proximal fusion level for adult degenerative lumbar scoliosis. Fifty-one patients with adult degenerative lumbar scoliosis (mean age 64.6 years) who underwent posterior instrumentation were analyzed after a minimum 2-year follow-up. The average number of levels fused was 5.9 segments (range 3-9) with distal fusion at L5 in 30 patients and S1 in 21 patients. The upper instrumented vertebra (UIV) ranged from T9 to L2. According to the relationship between UIV, horizontal vertebra (HV) and upper end vertebra (UEV), the patients were divided into three groups in the coronal plane: Group HV (UIV = HV or above); Group HV-UEV (UIV = between HV and UEV); and Group UEV (UIV = UEV or below). In the sagittal plane; the patients were divided into Group T9-10 (UIV = T9-10), Group T11-12 and Group L1-2. Proximal adjacent segment disease (ASD) was identified in 13 (25 %) out of 51 patients, including junctional kyphosis (n = 5), compression fractures (n = 4), progression of disc wedging (n = 2) and spinal stenosis (n = 2). Group UEV had more ASD (9 of 16 patients) compared to Group HV (2 of 21 patients) and Group HV-UEV (2 of 14 patients). It appeared that neutral vertebra could be a criterion for the selection of UIV in the coronal plane. Among the groups divided in the sagittal plane, proximal ASD was found in 47 % of 19 patients in Group L1-2, which was notably higher than 9 % in Group T9-10 and 20 % in Group T11-12. Proximal adjacent segment disease developed more commonly when the proximal fusion stopped at the UEV or below in adult degenerative lumbar scoliosis. UIV must be above UEV in the coronal plane. Fusion to T11 or T12 was acceptable when UIV was above UEV, since there was no significant difference in the rate of proximal adjacent segment between fusion to T10 and fusion to T11 or T12.

Risk factors for adjacent segment disease after lumbar fusion

The incidence of adjacent segment problems after lumbar fusion has been found to vary, and risk factors for these problems have not been precisely verified, especially based on structural changes determined by magnetic resonance imaging. The purpose of this retrospective clinical study was to describe the incidence and clinical features of adjacent segment disease (ASD) after lumbar fusion and to determine its risk factors. We assessed the incidence of ASD in patients who underwent lumbar or lumbosacral fusions for degenerative conditions between August 1995 and March 2006 with at least a 1-year follow-up. Patients less than 35 years of age at the index spinal fusion, patients with uninstrumented fusion, and patients who had not achieved successful union were excluded. Of the 1069 patients who underwent fusions, 28 (2.62%) needed secondary operations because of ASD and were included in this study. In order to identify the risk factors, we matched a disease group and a control group. The disease group consisted of 26 of the 28 patients with ASD, excluding the 2 patients for whom we did not have initial MRI data. Each patient in the disease group was matched by age, sex, fusion level and follow-up period with a control patient. The assumed risk factors included disc and facet degeneration, instability, listhesis, rotational deformity, and disc wedging. The mean age of the 28 patients with ASD requiring surgical treatment was 58.4 years, which did not differ significantly from that of the population in which ASD did not develop (58.2 years, p = 0.894). Of the 21 patients who underwent floating fusion, only 1 developed distal ASD. Facet degeneration was a significant risk factor (p < 0.01) on logistic regression analysis. The incidence of distal ASD was much lower than that of proximal ASD. Pre-existing facet degeneration may be associated with a high risk of adjacent segment problems following lumbar fusion procedures.

Proximal Adjacent Segment Disease following Posterior Instrumentation and Fusion for Degenerative Lumbar Scoliosis

Purpose: Adjacent segment disease (ASD) is major complication following spinal instrumentation and fusion. The purpose of the current study was to determine the prevalence and risk factors of proximal ASD following posterior instrumentation and fusion for degenerative lumbar scoliosis. Materials and Methods: Seventy-two patients (mean age 64.8 years) who had undergone decompression and fusion with pedicle screw instrumentation were evaluated. The average follow-up was 4.7 years. Twenty-five patients had additional interbody fusion at the lower lumbar spine. The average number of levels fused was 5.1 segments (range 1-9). The upper instrumented vertebrae ranged from T9 to L4. The lower instrumented vertebrae were L5 and S1. Results: Proximal ASD developed in 17 (24%) of 72 patients, including compression fractures (n=6), junctional kyphosis (n=5), spinal stenosis (n=4), and symptomatic disc collapse (n=2). The preoperative scoliotic angle, lumbar lordosis, thoracic kyphosis, and coronal and sagittal C7 plumb were not associated with the development of proximal ASD. There was a close correlation between the level of the upper instrumented vertebrae and the development of ASD (p=0.001). When fusion did not extend beyond the lumbar vertebra, ASD occurred in 15 (38.5%) of 39 patients. In contrast, when fusion extended up to the thoracic vertebrae, ASD occurred in 2 (6.1%) of 33 patients. The improvement in the Oswestry score was superior to the group without ASD (p=0.001). Conclusion: The prevalence of symptomatic ASD at the proximal segment was 24% after posterior instrumentation and fusion for degenerative lumbar scoliosis. The cephalad extent of fusion was the most significant risk factor for the development of proximal ASD.

106. Adjacent Segment Disease Following Posterior Instrumentation and Fusion for Degenerative Lumbar Scoliosis

Purpose: Adjacent segment disease (ASD) is major complication following spinal instrumentation and fusion. The purpose of the current study was to determine the prevalence and risk factors of proximal ASD following posterior instrumentation and fusion for degenerative lumbar scoliosis. Materials and Methods: Seventy-two patients (mean age 64.8 years) who had undergone decompression and fusion with pedicle screw instrumentation were evaluated. The average follow-up was 4.7 years. Twenty-five patients had additional interbody fusion at the lower lumbar spine. The average number of levels fused was 5.1 segments (range 1-9). The upper instrumented vertebrae ranged from T9 to L4. The lower instrumented vertebrae were L5 and S1. Results: Proximal ASD developed in 17 (24%) of 72 patients, including compression fractures (n=6), junctional kyphosis (n=5), spinal stenosis (n=4), and symptomatic disc collapse (n=2). The preoperative scoliotic angle, lumbar lordosis, thoracic kyphosis, and coronal and sagittal C7 plumb were not associated with the development of proximal ASD. There was a close correlation between the level of the upper instrumented vertebrae and the development of ASD (p=0.001). When fusion did not extend beyond the lumbar vertebra, ASD occurred in 15 (38.5%) of 39 patients. In contrast, when fusion extended up to the thoracic vertebrae, ASD occurred in 2 (6.1%) of 33 patients. The improvement in the Oswestry score was superior to the group without ASD (p=0.001). Conclusion: The prevalence of symptomatic ASD at the proximal segment was 24% after posterior instrumentation and fusion for degenerative lumbar scoliosis. The cephalad extent of fusion was the most significant risk factor for the development of proximal ASD.