Development Of Adjacent Segment Disease Research Articles

Index and Adjacent Level Kinematics After Cervical Disc Replacement and Anterior Fusion

Prospective, randomized trial. To assess the in vivo kinematics of the cervical spine after cervical fusion and arthroplasty. Compared with spinal fusion, disc replacement may impede the development of adjacent segment disease. To achieve this goal, any arthroplasty device should achieve desired spinal alignment while maintaining physiologic spinal motion at both the operated and surrounding motion segments. As part of a multicenter, prospective, randomized Food and Drug Administration IDE clinical evaluation of the porous coated motion artificial cervical disc, patients underwent either a single-level total disc replacement (TDR; 272 patients) or anterior cervical discectomy and fusion (ACDF; 182 patients) for treatment of cervical radiculopathy or myelopathy. Neutral, flexion, and extension radiographs of the cervical spine obtained before surgery, and at 3, 6, and 12 months after surgery were assessed. Quantitative assessments and comparisons of motion patterns were produced using validated computer-assisted methods. Kinematic parameters, including segmental rotation, translation, center of rotation (COR), disc height, and disc angle were calculated. Cervical TDR preserved angular motion at the operated level, although the range was reduced from 8.0° before surgery to 6.2° at 12 months after surgery (P < 0.001). Significantly after TDR, adjacent-level angular motion was unchanged. In patients treated with fusion, angular motion at the superior adjacent level increased from 9.6° before surgery to 11.0° (P = 0.003) at 12 months, with a trend toward increased postoperative translation (P = 0.07). For the TDR group, the horizontal COR averaged 0.8 mm posterior to the disc center before surgery and 0.2 mm anterior to the center at 12 months after TDR (P < 0.001), and the vertical COR averaged 2.5 mm below the endplate before surgery and 4.0 mm below at 12 months (P = 0.001). COR at the adjacent levels was unaltered by fusion or TDR. Lordotic alignment and disc height at the index level increased after intervention in both groups. TDR with the porous coated motion implant is able to restore and maintain lordotic alignment and disc height and maintain angular motion while allowing for similar translation to that seen before surgery. In contrast, after ACDF, the superior adjacent level developed increased angular motion compared with preoperative range of motion. This study provides in vivo data regarding the functioning of TDR and ACDF and their impact on adjacent-level kinematics.

Arthrodesis to L5 versus S1 in long instrumentation and fusion for degenerative lumbar scoliosis

There is a debate regarding the distal fusion level for degenerative lumbar scoliosis. Whether a healthy L5-S1 motion segment should be included or not in the fusion remains controversial. The purpose of this study was to determine the optimal indication for the fusion to the sacrum, and to compare the results of distal fusion to L5 versus the sacrum in the long instrumented fusion for degenerative lumbar scoliosis. A total of 45 patients who had undergone long instrumentation and fusion for degenerative lumbar scoliosis were evaluated with a minimum 2 year follow-up. Twenty-four patients (mean age 63.6) underwent fusion to L5 and 21 patients (mean age 65.6) underwent fusion to the sacrum. Supplemental interbody fusion was performed in 12 patients in the L5 group and eleven patients in the sacrum group. The number of levels fused was 6.08 segments (range 4-8) in the L5 group and 6.09 (range 4-9) in the sacrum group. Intraoperative blood loss (2,754 ml versus 2,938 ml) and operative time (220 min versus 229 min) were similar in both groups. The Cobb angle changed from 24.7 degrees before surgery to 6.8 degrees after surgery in the L5 group, and from 22.8 degrees to 7.7 degrees in the sacrum group without statistical difference. Correction of lumbar lordosis was statistically better in the sacrum group (P = 0.03). Less correction of lumbar lordosis in the L5 group seemed to be associated with subsequent advanced L5-S1 disc degeneration. The change of coronal and sagittal imbalance was not different in both groups. Subsequent advanced L5-S1 disc degeneration occurred in 58% of the patients in the L5 group. Symptomatic adjacent segment disease at L5-S1 developed in five patients. Interestingly, the development of adjacent segment disease was not related to the preoperative grade of disc degeneration, which proved minimal degeneration in the five patients. In the L5 group, there were nine patients of complications at L5-S1 segment, including adjacent segment disease at L5-S1 and loosening of L5 screws. Seven of the nine patients showed preoperative sagittal imbalance and/or lumbar hypolordosis, which might be risk factors of complications at L5-S1. For the patients with sagittal imbalance and lumbar hypolordosis, L5-S1 should be included in the fusion even if L5-S1 disc was minimal degeneration.

Does lumbar fusion increase the risk of disc degeneration of the adjacent segment?

AbstractSeveral reviews have attempted to establish whether there is an association between adjacent segment disorder and spinal fusion. None of these studies used an evidence‐based approach or solely focused on studies utilizing controls. The goal of this article is to identify any significant link between lumbar or lumbosacral spinal fusion and development of adjacent segment disease using literature with more than a 10‐year follow‐up, at least 15 subjects, and a control with no exposure to fusion. The published articles were obtained from a search of electronic databases and bibliographies of identified articles. The critical appraisal was performed using an epidemiological appraisal instrument. Five articles satisfied the inclusion criteria. From the literature, no definitive conclusion could be drawn regarding adjacent segment disorder as an outcome of spinal fusion. The failure of the literature to link adjacent segment disease to spinal fusion at least suggests the problem may not be widespread, but also fails to disprove the myriad of biomechanical concerns. Device manufacturers should address these concerns by furthering the development of motion preservation instrumentation and other innovations. Helping to drive this technology will be a larger data set of research with sound methodological quality and inclusion of accepted radiographic and functional outcomes. The reported findings underscore a need for information on spinal fusion and require a strategy for moving forward. © 2008 Wiley Periodicals, Inc.

Segmental Motion Adjacent to Anterior Cervical Arthrodesis

Prospective, observational study. The present study describes in a prospective setting the kinematics changes occurring at segments adjacent to a one-level cervical arthrodesis. The development of adjacent segment disease has been noticed by many clinicians. Whether symptoms develop due to fusion induced accelerated spondylosis or due to a natural development in a predisposed person is currently under debate. The motivation for introducing motion preservation procedures in the neck is primarily to protect the patients from developing symptomatic adjacent disc disease. To accept this rationale, it has to be demonstrated that a fusion creates an unfavorable biomechanical situation at adjacent levels. Forty-six patients underwent standard anterior cervical decompression and fusion using a cylindrical cage implant. Lateral radiographic views of the cervical spine in flexion and extension were obtained before surgery, and at 12 months of follow-up. Employing Distortion Compensated Roentgen Analysis, rotational and translational motion at adjacent levels was quantified prospectively. Rotational and translational motion at adjacent cranial and caudal levels did not exhibit a significant change between the preoperative state and the state 12 months after the operation. The assumption of an iatrogenically caused increased mobility by a one-level cervical fusion could not be confirmed 12 months after surgery.

4:03 125. Cervical Disc Arthroplasty: Preliminary Results of a Randomized Prospective Study of ACDF versus Prodisc-C for the Management of Cervical Spondylosis

BACKGROUND CONTEXT: Anterior cervical discectomy and fusion (ACDF) for spondylosis of the cervical spine with radiculopathy or myelopathy is one of the most successful operations performed in treatment of the degenerative spine. The rate of symptomatic adjacent segment disease that occurs in the future—close to 30%, with a reoperation rate of 2.9% per year—is concerning. The cervical disc replacement may provide a reconstructive alternative for the anterior cervical spine that may prove to provide an impact in the development of adjacent segment disease.

5:30 166. Radiographic changes following anterior cervical fusion in asymptomatic patients

BACKGROUND CONTEXT: Anterior Cervical Discectomy and Fusion (ACDF) is recommended for the treatment of cervical myelopathic and radiculopathic conditions. Diminished motion and altered biomechanics resulting from fusion however have raised significant concerns regarding the development of adjacent segment disease and recurrence of symptoms. The literature indicates that symptomatic disease occurs with an incidence of 2.9% per year. Such presumptions have supported the development of motion sparing alternatives, specifically cervical arthroplasty.

Adjacent Segment Disease after Lumbar or Lumbosacral Fusion: Review of the Literature

Review of the literature. Review the definition, etiology, incidence, and risk factors associated with as well as potential treatment options. The development of pathology at the mobile segment next to a lumbar or lumbosacral spinal fusion has been termed adjacent segment disease. Initially reported to occur rarely, it is now considered a potential late complication of spinal fusion that can necessitate further surgical intervention and adversely affect outcomes. MEDLINE literature search. The most common abnormal finding at the adjacent segment is disc degeneration. Biomechanical changes consisting of increased intradiscal pressure, increased facet loading, and increased mobility occur after fusion and have been implicated in causing adjacent segment disease. Progressive spinal degeneration with age is also thought to be a major contributor. From a radiographic standpoint, reported incidence during average postoperative follow-up observation ranging from 36 to 369 months varies substantially from 5.2 to 100%. Incidence of symptomatic adjacent segment disease is lower, however, ranging from 5.2 to 18.5% during 44.8 to 164 months of follow-up observation. The rate of symptomatic adjacent segment disease is higher in patients with transpedicular instrumentation (12.2-18.5%) compared with patients fused with other forms of instrumentation or with no instrumentation (5.2-5.6%). Potential risk factors include instrumentation, fusion length, sagittal malalignment, facet injury, age, and pre-existing degenerative changes. Biomechanical alterations likely play a primary role in causing adjacent segment disease. Radiographically apparent, asymptomatic adjacent segment disease is common but does not correlate with functional outcomes. Potentially modifiable risk factors for the development of adjacent segment disease include fusion without instrumentation, protecting the facet joint of the adjacent segment during placement of pedicle screws,fusion length, and sagittal balance. Surgical management, when indicated, consists of decompression of neural elements and extension of fusion. Outcomes after surgery, however, are modest.

Changes in Segmental Intervertebral Motion Adjacent to Cervical Arthrodesis: A Prospective Study

Prospective, observational. Quantify the changes in intervertebral motion adjacent to cervical arthrodesis over time. One of the frequently acknowledged sequelae following anterior cervical fusion is the development of adjacent segment disease. It has been argued that a spine fusion transfers stress to adjacent levels and results in increased compensatory motion. However, there are conflicting reports as to whether this actually occurs, and most of these are in vitro or retrospective clinical studies. Patients undergoing anterior cervical discectomy and fusion underwent a preoperative dynamic fluoroscopic study, followed by imaging at regular intervals after surgery. Imaging data were analyzed by a validated software system. Relative motion between adjacent vertebrae was then calculated, and changes in motion cephalad to the fusion followed over time. Twenty-one patients were analyzed. Mean follow-up was 13 months (10-22 months). Intervertebral motion adjacent to the fusion changed by more than 4 degrees in 4 of the 21 patients. However, on average, there was no difference between preoperative and postoperative motion for shear, flexion-extension, or vertical displacement at the anterior or posterior disc space. Although there was some individual variation, at a mean of 13 months following surgery, there was no significant change in the average junctional intervertebral motion. If fusion is going to affect adjacent motion, it appears that this does not consistently occur in the first 1 to 2 years following surgery. Additionally, there was no observable relationship between motion and development of degenerative changes during this time.