RhBMP-2 use in lumbar fusion surgery is associated with transient immediate post-operative leg pain.

Purpose: Supra-physiological rhBMP loads during spinal fusion may trigger local inflammation and post-operative radiculitis. MRI is an effective tool to detect nerve root compression in severe post-operative leg pain. The aim of this study was to determine if recombinant bone morphogenic protein 2 (rhBMP-2) is associated with immediate post-operative leg pain without evidence of root compression using MRI.

Method: All patients undergoing posterolateral and posterior interbody lumbar spinal fusions with rhBMP-2 between July 2007 and January 2009 at a single surgeon practice were retrospectively reviewed for incidence of severe immediate post-operative leg pain. Patients that presented with immediate post-operative leg pain were interviewed and Oswestry Disability Indices calculated.

Results: Sixty-four rhBMP-2 treated patients and 40 controls were included. Pre-operative demographics and diagnoses were similar and inter-body cages were used equally. Immediate post-operative leg pain incidence was 25 and 12.5% in the rhBMP-2 and non-rhBMP-2 groups, respectively. 17.2% of the patients treated with rhBMP-2 had immediate post-operative leg pain without evidence of nerve root compression on MRI versus 7.5% of the patients treated without rhBMP-2. At follow-up, leg pain incidence was 11.6 and 7.6% in rhBMP-2 and non-rhBMP-2 groups, respectively. There was no difference in Oswestry Disability Indices between groups (36.5 ± 31.2 vs. 23.0 ± 25.5).

Conclusion: RhBMP-2 associated radiculitis presenting as immediate post-operative leg pain without MRI evidence of neuronal compression occurs in 17% of the patients with rhBMP-2 assisted fusion. Patients should be pre-operatively counselled regarding immediate post-operative leg pain with rhBMP-2.

Level Of Evidence: III.