Safety and Efficacy of Recombinant Human Bone Morphogenetic Protein-2 in Multilevel Posterolateral Lumbar Fusion in a Prospective, Randomized, Controlled Trial

Abstract

Objective: This study is an investigator-initiated, prospective, randomized, controlled study to evaluate the efficacy and safety of the combined use of recombinant human BMP-2 (rhBMP-2) and a hydroxyapatite (HA) carrier in multilevel fusion in patients with adult spinal deformity (ASD).

Methods: Thirty patients underwent posterolateral fusion for lumbar spinal deformities at 3 to 5 segments between L1 and S1. The patients received rhBMP-2+HA or HA on the left or right side of the transverse processes. They were followed up regularly at 1, 3, 6, and 12 months postoperatively. Fusion was defined according to the bone bridging on computed tomography scans. The fusion rate per segment was subanalyzed. Function and quality of life as well as pain in the lower back and lower extremities were evaluated.

Results: The union rate for the rhBMP-2+HA group was 100% at 6 and 12 months. The union rate for the HA group was 77.8% (21 of 27) at 6 months and 88.0% (22 of 25) at 12 months (p = 0.014 at 6 months; not significant at 12 months). All segments were fused at 6 and 12 months in the rhBMP-2+HA group (p < 0.001). In the HA group, 108 of 115 segments (93.5%) were fused at 6 months and 105 of 109 segments (96.3%) at 12 months. Other clinical parameters (visual analogue scale, 36-item Short Form Health Survey, and Scoliosis Research Society-22 scores) improved compared to baseline.

Conclusion: Combining rhBMP-2 and an HA carrier is a safe and effective method to achieve multilevel fusion in patients with ASD.

Keywords: Adult spinal deformity; Bone graft; Bone morphogenetic protein-2; Hydroxyapatite; Lumbar fusion; Posterolateral fusion.

Fig. 1.

Flow diagram showing study enrollment, allocation, follow-up, and analysis. rhBMP-2, recombinant human bone morphogenetic protein-2; HA, hydroxyapatite.

Fig. 2.

Characteristics of fusion mass in the postoperative period. (A) Fusion mass on a 1-month postoperative plain radiograph. (B) A 12-month postoperative plain radiograph showed a more prominent fusion mass on the rhBMP-2 site. (C) Fusion mass on a 6-month postoperative CT scan. Although fusion mass was detected at both sites, patients with the HA carrier showed suspicious nonunion lesion of fusion mass (arrow). (D) Fusion mass on a 12-month postoperative CT scan. Continuity of fused mass is more prominent and uniformly observed at the rhBMP-2 than at the control site. Defect of fusion mass at the control site is still noted (arrow). CT, computed tomography; rhBMP-2, recombinant human bone morphogenetic protein-2; HA, hydroxyapatite.