Lytton A. Williams

Stability provided by the sternum and rib cage in the thoracic spine

Study Design. Multidirectional flexibility tests were conducted on 10 human thoracic spines with intact rib cage. Objectives. To determine the amount of stability the rib cage imparts to the thoracic spine and to show the amount of stability lost by a sternal fracture. Summary of Background Data. There is no published study of biomechanical testing of human cadaveric specimens with the rib cage intact. Methods. In this study, 10 human cadaveric thoracic spines with the rib cage intact were tested using a biaxial material testing machine and an opto-electronic three-dimensional motion measuring device (Opto-trak 3020). The specimens were tested in axial compression, axial rotation, lateral bending, and flexion/extension. First, the specimens were tested through all four loading types with the sternum and rib cage intact. Next, the sternum was fractured at the sternomanubrial junction displacing the proximal fragment posteriorly. Lastly, the entire rib cage was removed. Results. The rib cage increased the stability of the thoracic spine by 40% in flexion/extension (P = 0.012), 35% in lateral bending (P = 0.008), and 31% in axial rotation (P = 0.008). An indirect flexion-compression type of sternal fracture decreased the stability of the thoracic spine by 42% in flexion/extension (P = 0.036), 22% in lateral bending (P = 0.038), and 15% in axial rotation (P = 0.011). Conclusion. The rib cage significantly increases the stability of the thoracic spine in flexion/extension, lateral bending, and axial rotation. A sternal fracture significantly decreases the stability of the thorax.

Measurements of lumbopelvic lordosis using the pelvic radius technique as it correlates with sagittal spinal balance and sacral translation

BACKGROUND CONTEXT Maintenance of normal lumbar lordosis is important in the treatment of spinal disorders. Many attempts have been made to quantify normal sagittal spinal alignment and lordosis using a C7 plumb line and segmental angulations of the spinal vertebrae. Little attention has been given to pelvic compensation as it correlates to lumbar lordosis and overall sagittal spinal alignment. Better methods of measuring lordosis, which correlate with sagittal spinal balance and pelvic compensation, are needed in treating patients with spinal disorders. PURPOSE To determine the correlation between lumbopelvic lordosis, pelvic rotation and sagittal spinal balance and standardize a method for measuring lumbopelvic lordosis, sacral translation, and sagittal spinal alignment. STUDY DESIGN Sagittal alignments using the C7 plumb line, Cobb angles, sacral plumb line and the pelvic radius (PR) technique were used to measure standing 36-inch lateral radiographs of patients with various spinal disorders. PATIENT SAMPLE A review of the records identified 62 patients with various spinal pathologies presenting to the (RGW) spine clinic that had standing lateral spine radiographs. Only radiographs that allowed positive identification of the C7 vertebral body, the entire thoracolumbar spine, the sacrum and both femoral heads were studied. These criteria allowed inclusion of 28 subjects in this study. The final population had 12 women and 16 men with an average age of 52 years (SD, 16.6 years; range, 20 to 84 years). OUTCOME MEASURES No outcomes measures were used in this study. METHODS Measurements for sagittal spinal balance and lumbopelvic lordosis were made on 36-inch standing lateral radiographs of adult patients. Measurements included the C7 plumb line, segmental angulations of spinal vertebrae (Cobb angles), sacral translation and the PR technique for lumbopelvic lordosis. Data were analyzed for significant correlation between lumbopelvic lordosis, sagittal spinal balance, sacral translation and total segmental lumbar lordosis using the Cobb method. RESULTS Our population averaged 50 degrees of total segmental lumbar lordosis from L1 to S1 (SD, 14.3; maximum, 89.5; minimum, 17.9). Nearly 75% of total segmental lumbar lordosis measured from L1 to S1 can be accounted for through the L4 to S1 superior end plates and 47% through L5 to S1 superior end plates in our population. Total segmental lumbar lordosis correlated with total thoracic kyphosis (r=0.45, p=.008). Total segmental lumbar lordosis measured by the Cobb method significantly correlated with sagittal spinal balance (r=-0.35, p=.022) and sacral translation (r=0.41, p=.016). Measurements for lumbopelvic lordosis significantly correlated with sagittal spinal balance (r=-0.33, p=.042), sacral translation (r=-0.70, p=.00002) and total segmental lumbar lordosis (r=0.82, p<.000001). Measurements for sacral translation and sagittal spinal balance also correlated significantly (r=0.35, p=.034). CONCLUSIONS Sacral translation, the C7 plumb line and lumbopelvic lordosis are useful measures for sagittal spinal balance. Lumbopelvic lordosis and sacral translation can be correlated to the sagittal spinal balance. Understanding these measurements and the range of lumbopelvic compensation can be extremely helpful in treating patients with spinal pathology and in avoidance of flatback deformity. Application of these measures would be especially helpful in the treatment of patients with spinal fusion, degenerative spondylosis, disc disease, fractures, and in the prevention of sagittal malalignment.

Microscopic lumbar discectomy results for 60 cases in professional and Olympic athletes

BACKGROUND CONTEXT There is no documented information indicating time for return to play after lumbar discectomy in professional and Olympic athletes. PURPOSE To determine the rate of return to sport and the average time of recovery in elite athletes undergoing microscopic lumbar discectomy (MLD). STUDY DESIGN Between 1984 and 1998, the senior author performed 60 MLDs on 59 professional and Olympic athletes with lumbar herniated nucleus pulposus. PATIENT SAMPLE Sixty consecutive MLDs performed on professional and Olympic athletes were reviewed. OUTCOME MEASURES The rate of return and the average time to return to sport were determined. Also, the distribution of pain and presence of neurologic deficits were recorded. METHODS A retrospective review was performed. RESULTS Follow-up indicated that all but 7 of the 60 cases had returned to their sport, including one who underwent a second MLD for a herniation at an adjacent level. The average time from surgery to return was 5.2 months for the entire group, with a range of 1 to 15 months. CONCLUSION MLD was effective in correcting the problems that forced the athletes to seek help, and the time to return often depends on factors other than their medical condition. Postoperatively, a complete trunk stabilization rehabilitation program was effective in returning these athletes to a high level of competition.

Nerve monitoring changes related to iliac artery compression during anterior lumbar spine surgery

BACKGROUND CONTEXT There are no studies in the literature that correlate compression of the iliac vessels resulting in obstruction of blood flow with changes in nerve monitoring parameters during anterior lumbar surgery. PURPOSE To determine whether there is significant compression of the iliac vessels that can cause temporary nerve root ischemia or limb ischemia that could be responsible for loss of somatosensory evoked potentials (SSEP) while retractors are in place for exposure during anterior lumbar interbody fusion (ALIF). SETTING Patients coming to the operating room for ALIF from levels L2-L3 to L5-S1 would be studied for nerve monitoring changes during the procedure with particular attention to the intervals just before placement of a retractor, while the retractor was in place and immediately after removal of the retractor. PATIENT SAMPLE Forty-five consecutive patients were studied for changes in SSEP and oxygen saturation (SaO(2)) while undergoing ALIF. OUTCOME MEASURES Patients were considered to have lost saturation if the SaO(2) decreased to below 90%. Patients were considered to have abnormal SSEP with any increase in latency and decrease in amplitude. METHODS SSEP and SaO(2) were monitored continuously and simultaneously before exposure of the disc spaces, during exposure with retractors in place and after removal of the retractors. RESULTS Thirteen of 23 patients with exposure at L4-L5 had both loss of SSEP signals and loss of SaO(2) with exposure. All 13 patients had return to normal saturation and recovery of the SSEP signals within 15 minutes of removal of the retractors. Both of these are significant correlations (p<.001). CONCLUSION This study showed that the majority (57%) of patients undergoing ALIF at the L4-L5 level are subject to compression of the left iliac vessels enough to cause desaturation distally as measured by pulse oxymetry. This vascular compromise, as well as the return to normal saturation, correlates with changes noted in SSEP soon after both deployment and removal of the retractors used for exposure. The mechanism appears to be a transient ischemic response. Failure of the SSEP signals to recover may be diagnostic of left iliac artery thrombosis.

Access Strategies for Revision in Anterior Lumbar Surgery

Study Design. Sixty-two consecutive patients undergoing anterior lumbar revision surgery from February 2000 to September 2007 were evaluated for approach strategies and complications. Objective. To determine the incidence of complications in these patients and to make recommendations on future revisions based on the results obtained. Summary of Background Data. Only 2 articles exist in the literature that address this situation and they have widely varying results in a small number of patients. This larger series may help give more certainty to the expectations for complications in patients undergoing revision anterior lumbar surgery. Methods. A concurrent database was maintained on these 62 consecutive patients. Preoperative strategies were evaluated and complications were tabulated as they occurred and later analyzed to arrive at recommendations for future similar cases. Results. Twenty-three patients had the same level revised and 39 patients had adjacent levels operated on. There were 3 venous injuries (4.8%), 3 arterial injuries (4.8%), and 1 ureteral injury (1.6%). All 3 arterial injuries occurred while approaching L3–L4 after L4 to S1 prior fusion or disc replacement. All 3 venous injuries and the ureteral injury occurred while approaching a previously operated level or levels. Six of these patients had the injuries repaired and the procedures completed with full recovery. One L5–S1 revision had the procedure aborted after a venous injury. There were no deaths. Conclusion. Although the incidence of complications in revisions is much greater than for index cases, the actual percentage of venous, arterial, and ureteral complications is certainly acceptable for patients who must have this type of surgery. Only very experienced access surgeons should attempt revision surgery.

Acute traumatic myelopathy secondary to a thoracic cyst in a professional football player.

Study Design. Case report of acute traumatic myelopathy secondary to thoracic synovial cyst in a professional football player. Objective. To emphasize examination for myelopathy and describe the radiographic and magnetic resonance findings of a rare source of traumatic myelopathy. Background. Magnetic resonance imaging is the best initial evaluation for myelopathy in a traumatic setting. Heightened awareness during evaluation of a player involved in a traumatic incident allowed the diagnosis of potential cord damage and paralysis. Methods. A subject with symptoms resulting from a direct blow to the back was evaluated for myelopathy, with diagnosis assisted by magnetic resonance imaging used to pinpoint the source of the disorder. Results. The diagnosis allowed a surgical excision of the traumatic synovial cyst and full recovery of the injured football player. Conclusions. Awareness during examination for myelopathy in an acutely injured athlete is imperative to prompt the clinician to order the proper diagnostic studies and thereby embark on a surgical correction of the problem.