UNCONVENTIONAL PEDICLE SPINAL INSTRUMENTATION - THE BOMBAY EXPERIENCE

Study Design. A retrospective study of all patients who underwent spinal fusion between 1986 to 1989 with inexpensive, locally made unconventional pedicle spinal instrumentation systems was undertaken. Implants were made with passivated 316L stainless steel, and a single level of instrumentation cost $30. Objectives. To demonstrate that simple, cheap pedicle instrumentation systems are as effective as the conventionally available expensive systems, provided proper anterior column support is maintained. Methods. Ninety out of 102 patients were available for review. Average follow-up was 41 months (range, 22 to 60 months). Implant failures, screw placement, fusion rates, infection, neurologic deficit due to the implant, patient satisfaction, and the benefit of anterior column grafting with the unconventional pedicle spinal instrumentation systems in the long term were evaluated. Results. Forty-four out of 467 screws failed (9%) in 16 patients, seven of whom were symptomatic. There were no plate failures. On comparing burst fractures with (n = 12) and without (n = 10) anterior column grafting, the latter group had a significant increase in implant failures, loss of sagittal alignment, and the time required to fusion. Overall, fusion occurred within 6.5 months. Conclusions. Anterior column reconstruction in anterior column-deficient spines will re-create the normal biomechanics and significantly reduce the incidence of implant failures and loss of sagittal alignment with these systems. Pedicle screw failure in itself is not necessarily associated with a bad result. These inexpensive, locally made unconventional systems, with the proper understanding of biomechanics and creation of appropriate load-sharing constructs, are as good as the conventional systems available today.