A Case of Psoas Ossification From the Use of BMP-2 for Posterolateral Fusion at L4–L5

In Brief Study Design. Case report. Objective. Describe a complication from the use of bone morphogenetic protein-2 (BMP-2) for posterolateral lumbar fusion. Summary of Background Data. N/A, case report. Methods. The patient is a 69-year-old white male with a 1 year history of back and right leg pain with a foot drop due to spinal stenosis and a degenerative spondylolisthesis at L4–L5. Surgery for decompression and instrumented fusion was performed using BMP. Results. Within 3 months after surgery the patient developed pain along his iliac wing, groin, and greater trochanter on the right side. Work up over the next several months included a bone scan, radiographs, Dexa scan, computed tomography scan, and magnetic resonance imaging with gadolinium and fat suppression. These tests showed extensive bone formation in the psoas and iliacus on the right side. The bone has persisted at least 2 years after surgery and shows no sign of resorption. Conclusion. BMP-2 can cause heterotopic bone formation when used for posterolateral lumbar fusion. This is a patient with back and leg pain due to spinal stenosis and degenerative spondylolisthesis. A decompression and instrumented fusion was performed using BMP-2. The patient developed pain along his iliac wing, groin, and greater trochanter on the right side. Work-up showed bone formation consistent with his pain.