Transpedicular injection of rhBMP-2 with β-tricalcium phosphate to reduce the proximal junctional kyphosis after adult spinal deformity correction: preliminary study

Abstract

Abstract The aim of this preliminary study was to assess the impact of injecting recombinant human bone morphogenetic protein-2 (rhBMP-2) with β-tricalcium phosphate (β-TCP) carrier into the uppermost instrumented vertebra (UIV) during surgery to prevent the development of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). The 25 patients from study group had received 0.5 mg rhBMP-2 mixed with 1.5 g β-TCP paste injection into the UIV during surgery. The control group consisted of 75 patients who underwent surgery immediately before the start of the study. The incidences of PJK and PJF were analyzed as primary outcomes. Spinopelvic parameters and patient-reported outcomes were analyzed as secondary outcomes. Hounsfield unit (HU) measurements were performed to confirm the effect of rhBMP-2 with β-TCP on bone formation at preoperative and postoperative at computed tomography. PJK and PJF was more occurred in control group than study group (p = 0.02, 0.29, respectively). The HU of the UIV significantly increased 6 months after surgery. And the increment at the UIV was also significantly greater than that at the UIV-1 6 months after surgery. Injection of rhBMP-2 with β-TCP into the UIV reduced PJK and PJF rates 6 months after surgery with new bone formation.