Hypomagnesemia in postoperative spine fusion patients.

STUDY DESIGN: This was a retrospective review of 49 consecutive patient charts and a prospective study of 44 consecutive patients who underwent spinal fusion. OBJECTIVE: To determine the incidence and clinical significance of hypomagnesemia after spinal fusion. SUMMARY OF BACKGROUND DATA: Hypomagnesemia may be seen in 61% of patients in postoperative intensive care and may be associated with increased mortality. However, symptomatic hypomagnesemia is rare. METHODS: A retrospective review of the charts of 49 consecutive patients who underwent spine fusion was completed to determine postoperative magnesium levels. Twenty-seven patients with postoperative hypomagnesemia received routine magnesium replacement regardless of symptoms. Forty-four patients who underwent spine fusion were studied prospectively for postoperative hypomagnesemia. Prospectively studied observational patients who developed hypomagnesemia were treated only when clinical signs or symptoms of magnesium deficiency occurred. RESULTS: Postoperative hypomagnesemia occurred in 28 of 49 retrospectively studied patients who underwent spine fusion (57%) and 38 of 44 prospectively studied patients who underwent spine fusion (86%). Symptoms associated with hypomagnesemia developed in three of 44 prospectively studied and two of 49 retrospectively studied patients who underwent spine fusion (7% and 4%, respectively). The combined incidence for symptomatic hypomagnesemia was five of 93 patients. (5.4%). The majority of patients from the prospective study with postoperative hypomagnesemia were asymptomatic, and their magnesium levels returned to normal within 4 days, with or without treatment. CONCLUSIONS: This study confirmed a high incidence of hypomagnesemia in patients who underwent spine fusion, although only 5.4% developed clinical signs or symptoms of magnesium deficiency. The cause of hypomagnesemia remains speculative.

Cervical spine injury in a boxer: should mandatory screening be instituted?

Cervical spine fracture is a rare, yet potentially catastrophic complication associated with boxing. Neurologic deficits, ocular injuries, or other traumatic musculoskeletal injuries have been commonly reported. Symptoms of cervical spine injury may be minimal or absent. Cervical spine fracture may be undiagnosed and unreported in boxers with presumed soft-tissue injury to the head and neck. We describe a young athlete who sustained a transient spinal cord injury while boxing, which required a cervical spine fusion and postoperative immobilization in a halo vest. This athlete also had an os odontoideum, which placed him at significant risk for such an injury. Pre- and postparticipation screening of the cervical spine should be considered in all boxers.

Quantification of lumbar nerve root decompression using somatosensory-evoked potentials.

Intraoperative somatosensory-evoked potential (SSEP) data were collected prospectively in a consecutive series of patients with an acute lumbar herniated nucleus pulposus (HNP). Each patient underwent an open limited diskectomy, hemilaminotomy, and partial foraminotomy. The sequence of diskectomy and bony decompression was randomized, and the extent of foraminotomy was standardized. SSEP data were recorded after each operative procedure and were coded for blind interpretation. SSEP tracings were compared with each patient's baseline for changes in latency and amplitude. In the overall study, changes in amplitude and latency produced by diskectomy versus bony decompression were not statistically significant. In the six patients with lateral recess stenosis (LRS), a statistically significant reduction in latency was observed after bony decompression (averaging -2.05 ms) compared with diskectomy (-0.62 ms). In patients with underlying LRS and a HNP, minimally invasive techniques addressing the disc only may be inadequate to decompress a lumbar nerve root.

Accuracy of pedicle screw placement in lumbar fusions by plain radiographs and computed tomography.

STUDY DESIGN: Postoperative radiographs and computed tomography scans were used to evaluate 74 pedicle screws in 16 consecutive patients who underwent lumbar spine fusion with pedicle screw fixation. OBJECTIVE: To evaluate pedicle screw placement using plain radiographs versus computed tomographic scans. SUMMARY OF BACKGROUND DATA: Plain radiographs are the primary means of assessing pedicle screw placement. Comparison of plain radiographs and computed tomography has not been done. METHODS: Screws were graded as IN, OUT, or QUESTIONABLE; the direction of misplacement was noted. All evaluations were performed independently by three observers. RESULTS: Fewer screws were clearly within the pedicle on computed tomography when compared with plain radiographs. Computed tomography showed 10 times as many screws violating the medial cortex as did radiographs. Interobserver differences were not statistically significant. Intraobserver differences approached statistical significance when the two tests were compared. No recognized neurologic complications resulted from pedicle screw placement. CONCLUSIONS: Plain radiographs alone may not accurately reveal pedicle screw placement. Plain radiographs and thin section computed tomographic scans should be used to evaluate postoperative neurologic deficits in patients undergoing instrumented lumbar spine fusion with pedicle screws.

Sacral insufficiency fractures in rheumatoid arthritis.

METHODS: All patients with rheumatoid arthritis (RA) attending an outpatient rheumatology clinic at a major military medical center over 6 years were included in follow-up for the development and subsequent course of sacral insufficiency fractures. RESULTS: Sacral insufficiency fractures developed in 4 of 386 patients. Consistent with the literature, patients were female, elderly, and/or postmenopausal, had severe or long-standing disease, and were taking corticosteroids. The correct diagnosis was initially delayed because radiographs were normal but was later established with bone scan and sacral computerized tomography. Each patient improved with calcitonin and/or physical therapy over time. CONCLUSIONS: Patients with RA represent a unique subgroup predisposed to insufficiency fractures because of multiple osteoporotic risk factors. Patients who have RA and acute low back or buttock pain should be evaluated aggressively for sacral insufficiency fractures with bone and/or computed tomography scans regardless of normal plain radiographs.

Stabilization of thoracic spine fractures resulting in complete paraplegia. A long-term retrospective analysis.

STUDY DESIGN: The impact of surgical stabilization on initial rehabilitation and complications in patients with traumatic thoracic level paraplegia was investigated. One hundred thirteen patient records were retrospectively reviewed. SUMMARY OF BACKGROUND DATA: Forty-six patients had been treated with surgical stabilization and fusion. Nineteen patients had been treated by laminectomy alone. Forty-eight patients had been treated nonoperatively. The most common mechanism of injury was a motor vehicle accident (52.6%). The mean follow-up was 8.4 years. METHODS: All inpatient and outpatient records at Craig Hospital were reviewed for patients who had sustained a thoracic spine fracture (T2-T9) that resulted in complete paraplegia (Frankel A). All patients were followed for a minimum of 5 years. Data were collected regarding initial length of inpatient rehabilitation, as well as early and late complications that affected rehabilitation and function during follow-up. This information was analyzed by treatment group. RESULTS: There was a statistically significant difference in the length of initial rehabilitation days between the surgically stabilized group and the laminectomy-only group. There was a trend toward fewer in-patient rehabilitation days between the surgically stabilized group and the nonoperatively treated group. The surgically treated group had twice as many complications as the nonoperative group. CONCLUSIONS: The surgical stabilization of thoracic (T2-T9) spine fractures with complete paraplegia tends to decrease initial rehabilitation days but is associated with increased overall complications. The treatment of this patient group clearly must be individualized.