136. OP-1 AS AN ALTERNATIVE TO POSTEROLATERAL GRAFT FOR INSTRUMENTED SINGLE-LEVEL SPINAL FUSION

Purpose of the study: Although the iliac autograft is the gold standard for single-level intervertebral fusion, complications and morbidity related to autologous graft harvesting from the iliac crest remain a point of concern. Bone morphogenic protein (BMP) has proven advantages for fusion of the intersomatic and posterolateral graft. This study compared the efficacy and tolerance of OP-1 compared with an autologous graft in patients with symptomatic spondylolisthesis. This study reports the preliminary results of a prospective randomised controlled trial comparing OP-1 with an iliac autologous graft for instrumented single-level posterolateral fusion for arthrodesis of grade 1 spondylolisthesis. Material and methods: Lamino-arthrectomy associated with a posteriolateral instrumented arthrodesis with an iliac autologous graft or a mixture of OP-1 and local autologous graft material was performed in 27 patients with spondylolisthesis leading to lumboradiculalgia or neurogenic claudication. The final outcome was time to fusion at one year on the scanner and plain x-rays. The Oswestry score and pain at the harvesting site as well as side effects were also noted. Results: The cohort included 27 patients. Three were excluded from the analysis, leaving 24 patients assessed at one year. The demographic data were comparable for the two groups regarding mean age (64 years versus 69 years for the OP-1 group). At one year, ten radiographically certain fusions were noted in the control group and eight in the OP-1 group. Two nonunions and one doubtful fusion were noted in the control group compared with three doubtful fusions in the OP-1 group. The mean Oswestry score was comparable in the two groups. The mean score in the control group improved from 49.5 to 28.5 compared with 45.9 to 29.7 in the OP-1 group. There was no secondary effect attributable to use of OP-1. There were no cases of systemic toxicity, nor heterotopic calcification or restenosis for the 11 patients in the OP-1 group. Conclusion: A fusion rate of 73% without secondary effects attributable to OP-1 was observed in this preliminary study. This study allows the conclusion that this technique is reliable, safe and, in terms of fusion, a valid alternative to autologous iliac crest graft. The main advantage resulting from the use of OP-1 is to avoid the morbidity linked with harvesting the iliac graft.