Patricia G. Anderson

Posterior reduction and anterior lumbar interbody fusion in symptomatic low-grade adult isthmic spondylolisthesis: short-term radiological and functional outcome

Abstract. The aim of this study was to evaluate the short-term radiological and functional outcome of surgical treatment for symptomatic, low-grade, adult isthmic spondylolisthesis. Twelve patients underwent a monosegmental fusion for symptomatic spondylolisthesis. Posterior reduction with pedicle screw instrumentation was followed by second-stage anterior interbody fusion with a cage. All patients underwent a decompressive laminectomy. At an average of 2.1 (range 1.4–3.0) years following surgery, all patients completed the Oswestry questionnaire, VAS back pain score and a questionnaire detailing their work status. Radiographs were evaluated for maintenance of reduction and fusion. The patients (nine male, three female; mean age 42, range 22–54 years) had experienced preoperative symptoms for an average of 38 (range 6–96) months. An average preoperative slip of 21% (range 11–36%) was reduced to 7% (range 0–17%). Reduction of slip was maintained at latest follow-up, at which time the average VAS score was 2.8 (range 0–8) and the average Oswestry score was 13 (range 0–32). All patients achieved a successful fusion. There were no postoperative nerve root deficits. All patients stated that they would be prepared to undergo the same procedure again if required. Seventy-five percent returned to their pre-symptom work status. Our findings suggest that posterior reduction and anterior fusion for low-grade adult isthmic spondylolisthesis may yield good functional short-term results. A high fusion rate and maintenance of reduction with a low complication rate may be expected. Further follow-up is necessary to evaluate long-term outcome.

Spinal osteotomy in patients with ankylosing spondylitis: Complications during first postoperative year

Study Design. A historic cohort to determine short-term complications after 115 corrective osteotomies of the cervical and lumbar spine in patients with ankylosing spondylitis. Objectives. To describe the nature of complications of spinal osteotomies and sequelae. Summary of Background Data. Little is known about the rate and nature of complications after spinal osteotomy in these patients. Methods. A chart review of 106 patients (age, 21–82 years) was conducted. The following surgical techniques were performed: cervical-thoracic extending osteotomy at C6-Th1 (n = 22), lumbar closing-wedge osteotomy (n = 62), polysegmental lumbar osteotomy (n = 20), or a combined anterior-posterior lumbar correction (n = 11). Results. Many complications (7.8% permanent neurologic deficit, 9.6% deep wound infections, and 10.4% major general complications) occurred after performing a spinal correction. Since 1998, there is a tendency for a lower rate of infections but a higher rate of neurologic and major general complications. Because of 27% deep wound infections and 18% major general complications, the technique of combined anterior and posterior surgery has been abandoned. Conclusion. High complication rates in this group of patients are partly due to the difficult surgery but also to the underlying disease. The surgery should be concentrated in specialized centers.

Provocative discography and lumbar fusion: is preoperative assessment of adjacent discs useful?

Study Design. A cohort study of clinical outcomes of lumbar fusion patients with preoperative assessment of adjacent levels by provocative discography. Objective. To evaluate whether the preoperative status of the adjacent discs, as determined by provocative discography, has an impact on the clinical outcome of lumbar fusion in chronic low back pain (LBP) patients. Summary of Background Data. The results of lumbar fusion in chronic LBP patients vary considerably and are hard to predict. It is believed that degenerative levels adjacent to a fused spinal segment may be a cause of continuing pain. In this respect, it is important to know whether preoperative degenerative or symptomatic adjacent levels have an adverse effect on patient outcomes after lumbar fusion. Methods. In 197 patients with an equivocal indication for lumbar fusion (two thirds were patients with prior spine surgery), the decision for either lumbar fusion or conservative management was determined by a temporary external transpedicular fixation trial. During the diagnostic workup, all patients had undergone provocative discography that included the assessment of the discs adjacent to the intended fusion levels. The individual changes in pain on a visual analog scale, assessed before treatment and at follow-up, and patient satisfaction were the measures of outcome. Results. In the 82 patients who underwent a lumbar fusion, no difference in outcome was found between those patients with degenerative or symptomatic discs adjacent to the fusion and those with normal adjacent discs. Conclusion. In this cohort study of chronic LBP patients with an uncertain indication for lumbar fusion, the preoperative status of adjacent levels as assessed by provocative discography did not appear to be related to the clinical outcome after fusion.

Computer-assisted pelvic surgery: An in vitro study of two registration protocols

An in vitro study was done to test the accuracy and functionality of computer-assisted surgery in pelvic orthopaedic surgery. The study was done on two fresh hips from one cadaver. In each hip, 10 titanium marker screws were inserted through standard pelvic osteotomy incisions. After a computed tomography scan was obtained the data were introduced into the navigation system. For the accuracy measurements the location of the center of the spherical heads of the marker screws was determined relative to a reference base attached to the pelvis using a special pointer that corresponded to the spherical head of the screws. A randomized trial was done with two surgeons to test the accuracy of two different anatomy-based registration protocols. The deviation between the virtual position of the marker screws in the pelvis, calculated by the computer after each anatomy based registration, and the real position were compared for each registration. Accuracy is not only related to the distance of the computed tomography slices and the necessary computed tomography field of view but also depends on the location of the point on the pelvis.

Are older adults more dependent on visual information in regulating self-motion than younger adults?

Older adults look at the ground more while they are walking than younger adults do. In the present study, the effect of blocking that exproprioceptive visual information on the walking pattern of older adults was investigated. The first 0.75 m of the floor in front of healthy young adults (n = 10, mean age = 26.0 years) and 2 groups of older adults (n = 10, mean age 65.7 years; and n = 9, mean age = 75.9 years) was occluded. The dependent variables were step velocity, step length, and step frequency. The effect of the manipulation on those kinematic variables increased with age. The older adults had a significant increase in velocity and step length. The possible use of optic flow information from the ground to regulate the velocity of self-motion is discussed.

Scheuermann kyphosis: the importance of tight hamstrings in the surgical correction.

Study Design. A historic cohort study of the sagittal alignment in 33 consecutive patients with surgically corrected thoracic Scheuermann kyphosis. Objectives. To determine if postsurgical imbalance, sagittal malalignment, and decreased lumbar-pelvic range of motion in patients with thoracic Scheuermann kyphosis is related to tight hamstrings. Summary of Background Data. Tight hamstrings are a frequent sign in Scheuermann kyphosis. The importance of tight hamstrings in the surgical management of Scheuermann kyphosis has not yet been studied. Methods. Thirty-three patients with Scheuermann kyphosis were managed by surgical correction and fusion. Tight hamstrings, lumbar-pelvic range of motion, and sagittal balance were evaluated. Sixteen patients had tight hamstrings, and 17 patients had nontight hamstrings. Hamstrings were considered tight if the popliteal angle was >30°. Results. Patients with tight hamstrings have a significantly greater risk of postoperative imbalance (P = 0.05), and these patients can only compensate for this risk by reducing their lumbar lordosis (P = 0.0227). Furthermore, the limitations in the lumbar and pelvic range of motion are predicted by tight hamstrings (P ≤ 0.005). Conclusion. Tight hamstrings can be considered as an important factor in the surgical management of thoracic Scheuermann kyphosis. Tight hamstring patients can be classified as “lumbar compensators” and as such are prone to overcorrection and imbalance. Preoperative assessment of the lumbar-pelvic range of motion and tight hamstrings should therefore be advised. Extensive fusion of the lumbar segments might compromise the lumbar compensation mechanism and induces further risk of imbalance.

Temporary External Transpedicular Fixation of the Lumbosacral Spine : A Prospective, Longitudinal Study in 330 Patients

Study Design. In this study, 330 patients with incapacitating low back pain underwent temporary external transpedicular fixation (TETF) of the lumbosacral spine in a prospective trial. Objective. To evaluate TETF as a test for selecting suitable candidates for segmental spinal fusion. Summary of Background Data. Few studies regarding TETF have been published, and contradictory results concerning predictive value and morbidity were reported. Methods. All patients were tested with the external fixator in two different positions: fixation and nonfixation. Before and during the test and at follow-up examination, pain was assessed on a Visual Analogue Scale (VAS). The TETF test was considered to be positive if the VAS score in the fixation state was 30 or more points lower than in the nonfixation state. Hence, a positive test would imply the decision to perform segmental lumbosacral fusion. When the reduction was less than 30 points, the test was negative. Individual pain reduction and working capacity were taken as measure of outcome. Results. Most of the patients in this study (62%) underwent spinal surgery previously. The positive and negative TETF groups were quite similar, but a large within-group variation was found. Within the fusion group of 123 patients, improvement in VAS scores and improvement in working capacity were not significantly better for the positive TETF group in comparison with the negative TETF group. Conclusion. In this heterogeneous group of chronic patients with low back pain, TETF of the spine (including a placebo trial) does not appear to be of value in selecting suitable candidates for spinal fusion.

Kinematic Magnetic Resonance Imaging Assessment of the Degenerative Cervical Spine: Changes after Anterior Decompression and Cage Fusion

Study Design A prospective cohort study. Objective Decompression and fusion of cervical vertebrae is a combined procedure that has a high success rate in relieving radicular symptoms and stabilizing or improving cervical myelopathy. However, fusion may lead to increased motion of the adjacent vertebrae and cervical deformity. Both have been postulated to lead to adjacent segment pathology (ASP). Kinematic magnetic resonance imaging (MRI) has been increasingly used to evaluate range of motion (ROM) of the cervical spine and ASP. Our objective was to measure ASP, cervical curvature, and ROM of individual segments of the cervical spine using kinematic MRI before and 24 months after monosegmental cage fusion. Methods Eighteen patients who had single-level interbody fusion were included. ROM (using kinematic MRI) and degeneration, spinal stenosis, and cervical curvature were measured preoperatively and 24 months postoperatively. Results Using kinematic MRI, segmental motion of the cervical segments was measured with a precision of less than 3 degrees. The cervical fusion did not affect the ROM of adjacent levels. However, pre- and postoperative ROM was higher at the levels immediately adjacent to the fusion level compared with those further away. In addition, at 24 months postoperatively, the number of cases with ASP was higher at the levels immediately adjacent to fusion level. Conclusions Using kinematic MRI, ROM after spinal fusion can be measured with high precision. Kinematic MRI can be used not only in clinical practice, but also to study intervention and its effect on postoperative biomechanics and ASP of cervical vertebrae.