Vertebral osteolysis after posterior interbody lumbar fusion with recombinant human bone morphogenetic protein 2: a report of five cases.

BACKGROUND: Recombinant human bone morphogenetic protein 2 (rh-BMP-2) is frequently used in an off-label fashion. Its application for posterior interbody fusion appears intuitive because its use obviates the need for iliac crest bone graft and shows higher fusion rates than with the use of local autologous bone graft. To date, there is no report of adverse outcomes with such use of rh-BMP-2.
PURPOSE: To draw attention to this unusual complication of posterior interbody lumbar fusion and to review the relevant literature. STUDY
DESIGN: Clinical report of five cases of vertebral osteolysis that developed postoperatively from lumbar transforaminal interbody fusion of the L5/S1 motion segment using cages and rh-BMP-2.
METHODS: Sixty-eight patients underwent transforaminal lumbar interbody fusion for spondylolisthesis or degenerative disc disease with discogenic back pain. Five of these 68 patients developed vertebral osteolysis within 4 months from their surgery. Their clinical presentation and radiographic findings are presented in this case series.
RESULTS: Each one of these five patients had uneventful surgery and postoperative recovery. Their back and leg pain improved in the immediate postoperative period. However, each patient reported worsening back pain with variable radicular pain as early as 4 weeks and as late as 3 months after the index procedure. Diagnostic workup revealed evidence of vertebral osteolysis typically involving the L5 vertebral body. In all five patients, osteolytic defects filled in spontaneously, and symptoms typically resolved within an additional 3 months of nonoperative care.
CONCLUSIONS: Vertebral osteolysis can occur with the use of rh-BMP-2 in posterior lumbar interbody fusions. Violation of the end plate during decortication may be a contributing factor. Symptoms often resolve spontaneously.