Survivorship analysis of VSP spine instrumentation in the treatment of thoracolumbar and lumbar burst fractures.

We used survivorship analysis to study 21 burst fractures that were treated with posterior VSP spine implant and fusion, each of which was over two motion segments. There were two treatment classes: 1) eight patients whose surgery included anterior bone grafting (augmentation), seven of which were done by the transpedicular approach; and 2) 13 patients whose surgery did not include anterior bone. Eight patients, seven of whom were in the second group, met at least one of the failure criteria. Life table calculations showed 100% implant survival through 22 months in the group treated with anterior bone augmentation, while the nonaugmented group showed 92% survival at 6 months, 68% survival at 9 months, 60% survival at 13 months, and 50% survival at 19 months. Statistical comparisons of the two groups resulted in P-values of 0.05 (Breslow) and 0.04 (Mantel-Cox). Based on this method of analysis, VSP instrumentation and two-level fusion is suitable surgical treatment for many burst fractures, but high failure rates may result if anterior bone augmentation is not performed.