EVALUATION OF A NEW RHBMP-2 FORMULATION IN TWO LEVEL POSTEROLATERAL LUMBAR SPINE FUSIONS

Abstract

Preliminary results suggest that a new rhBMP-2 formulation may provide an alternative for autologous bone graft in two-level posterolateral fusions

The purpose of this study was to compare the success of instrumented two level fusions using a new rhBMP-2 formulation versus iliac crest bone graft (ICBG). In this formulation, rhBMP-2 was at a concentration of 2mg/cc in a Biphasic Calcium Phosphate (60% hydroxyapatite/40% tricalcium phosphate) ceramic granule carrier. Twenty-nine patients were enrolled in this multicentered, prospective, randomized study. Either 30cc of rhBMP-2/BCP or fresh ICBG were used. Clinical evaluations were done preoperatively, at discharge and 1.5, three, six, twelve and twenty-four months including Oswestry Disability Index SF36, back pain and leg pain questionnaires. CT scan and xrays were independently assessed at six, twelve, and twenty-four months. Fusion criteria included bilateral bridging trabecular bone on each level, less than 3mm translation, less than five degrees angulation . Seventeen patients received ICBG and twelve received rhBMP-2/BCP. With the use of rhBMP-2 average OR time was reduced from 3.8 to 2.9 hours. Twenty-nine patients (100%) have reached twenty-four month followup. Clinical improvements were similar in both groups, however, fusion success was much improved with the use of rhBMP-2. At twenty-four months all patients receiving rhBMP-2/BCP were fused versus 58% of ICBG patients. These results suggest that rhBMP-2/BCP may have improved fusion success in challenging two level posterolateral fusions as compared to ICBG.