The effect of recombinant human bone morphogenetic protein-2 in single-level posterior lumbar interbody arthrodesis

In this prospective, randomized controlled trial, our objective was to assess both the clinical and radiographic effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) in patients treated with an instrumented single-level posterior lumbar interbody arthrodesis with polyetheretherketone cages.

Forty patients were randomized with a 1:1 ratio. Two patients who had a two-level arthrodesis (L4-L5 and L5-S1) were excluded. Patients completed the Oswestry Disability Index, the Short Form-36, and the visual analog scale preoperatively and postoperatively at three, six, twelve, and twenty-four months. Computed tomography scans with coronal and sagittal reconstructions were made at three, six, and twelve months postoperatively. Interbody arthrodesis was performed using polyetheretherketone cages, which were filled with 8 mg of rhBMP-2 in the study group and 2.5 mL of autologous bone in the control group.

Baseline demographic data showed no significant difference between groups, except for the body mass index, which was higher in the study group (p = 0.032). There were no significant differences in the clinical results (visual analog scale, Oswestry Disability Index, and Short Form-36) between the groups at each postoperative visit. At three months, end-plate resorption was noted around the cages filled with rhBMP-2 in all patients in the study group. No cage migration or subsidence was observed. Bridging trabecular bone scale scores and bone density measures were significantly lower in the study group. Osteolysis and ectopic bone formation occurred in seven of nineteen patients in the study group and did not occur in the control group. This did not result in radicular symptoms within the time span of this study. At one year, computed tomography scans showed osseous healing in all patients. There were no revision procedures.

This trial showed no clinical difference when rhBMP-2 was used in posterior lumbar interbody arthrodesis compared with autologous bone. On computed tomography scans, fusion was equally achieved, but trabecular bone formation occurred at a slower rate and interbody bone density was lower within the first year after surgery when rhBMP-2 was used. End-plate resorption, osteolysis, and ectopic bone formation were frequently noted in the rhBMP-2 group.