UNCONVENTIONAL PEDICLE SPINAL INSTRUMENTATION - THE BOMBAY EXPERIENCE

Study Design. A retrospective study of all patients who underwent spin al fusion between 1986 to 1989 with inexpensive, locally made unconven tional 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, che ap pedicle instrumentation systems are as effective as the conventiona lly available expensive systems, provided proper anterior column suppo rt is maintained. Methods. Ninety out of 102 patients were available f or review. Average follow-up was 41 months (range, 22 to 60 months). I mplant failures, screw placement, fusion rates, infection, neurologic deficit due to the implant, patient satisfaction, and the benefit of a nterior column grafting with the unconventional pedicle spinal instrum entation systems in the long term were evaluated. Results. Forty-four out of 467 screws failed (9%) in 16 patients, seven of whom were sympt omatic. There were no plate failures. On comparing burst fractures wit h (n = 12) and without (n = 10) anterior column grafting, the latter g roup had a significant increase in implant failures, loss of sagittal alignment, and the time required to fusion. Overall, fusion occurred w ithin 6.5 months. Conclusions. Anterior column reconstruction in anter ior column-deficient spines will re-create the normal biomechanics and significantly reduce the incidence of implant failures and loss of sa gittal alignment with these systems. Pedicle screw failure in itself i s not necessarily associated with a bad result. These inexpensive, loc ally made unconventional systems, with the proper understanding of bio mechanics and creation of appropriate load-sharing constructs, are as good as the conventional systems available today.