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Object The load-sharing score (LSS) of vertebral body comminution is predictive of results after short-segment posterior instrumentation of thoracolumbar burst fractures. Some authors have posited that an LSS > 6 is predictive of neurological injury, ligamentous injury, and the need for surgical intervention. However, the authors of the present study hypothesized that the LSS does not predict ligamentous or neurological injury. Methods The prospectively collected spinal cord injury database from a single institution was queried for thoracolumbar burst fractures. Study inclusion criteria were acute (< 24 hours) burst fractures between T-10 and L-2 with preoperative CT and MRI. Flexion-distraction injuries and pathological fractures were excluded. Four experienced spine surgeons determined the LSS and posterior ligamentous complex (PLC) integrity. Neurological status was assessed from a review of the medical records. Results Forty-four patients were included in the study. There were 4 patients for whom all observers assigned an LSS > 6, recommending operative treatment. Eleven patients had LSSs ≤ 6 across all observers, suggesting that nonoperative treatment would be appropriate. There was moderate interobserver agreement (0.43) for the overall LSS and fair agreement (0.24) for an LSS > 6. Correlations between the LSS and the PLC score averaged 0.18 across all observers (range −0.02 to 0.34, p value range 0.02–0.89). Correlations between the LSS and the American Spinal Injury Association motor score averaged −0.12 across all observers (range −0.25 to −0.03, p value range 0.1–0.87). Correlations describing the relationship between an LSS > 6 and the treating physician's decision to operate averaged 0.17 across all observers (range 0.11–0.24, p value range 0.12–0.47). Conclusions The LSS does not uniformly correlate with the PLC injury, neurological status, or empirical clinical decision making. The LSSs of only one observer correlated significantly with PLC injury. There were no significant correlations between the LSS as determined by any observer and neurological status or clinical decision making.

Objective Adjacent segment disease (ASD) requiring treatment or re-operation is a common problem after surgery on the lumbar spine. The hypothesis of this retrospective study was that ASD occurs less often following lumbar spine fusion in patients who undergo percutaneous minimally invasive (MIS) instrumentation than in those in whom open instrumentation is used. Methods A case-control study was performed on consecutive patients who had undergone staged single or two level anterior lumbar interbody fusion for degenerative conditions followed by open or MIS instrumentation from 2002 to 2005 in our institution. ASD was defined as that necessitating additional procedures for new symptoms related to an adjacent lumbar dermatome. Results One hundred and seventeen patients met the inclusion criteria. Of these, 53 had been followed up by chart or medical record review for longer than one year. There were 23 patients in the MIS group and 30 in the open group. Of the 30 patients in the open group, 9 had developed ASD (30%). Of the 23 patients in the MIS group, 7 had developed ASD (30%). This difference is not statistically significant (P = 1.00). Conclusion Contrary to our hypothesis, there was no significant difference in incidence of ASD in patients who had underwent open versus percutaneous instrumentation following anterior lumbar interbody fusion.