Irreducible Monteggia Fracture-Dislocation Secondary to an Entrapped Brachialis Tendon: A Case Report.

CASE: A 7-year-old boy sustained a Monteggia fracture-dislocation. Corrective osteotomy of the ulna was performed to restore proper forearm anatomy and achieve radial head reduction. Recurrent radial head instability was noted postoperatively, and magnetic resonance imaging indicated recurrent dislocation of the radial head with, notably, an entrapped brachialis tendon and annular ligament. Open reduction of the elbow was performed. Anatomic reduction of the radiocapitellar joint and full range of motion without instability was achieved. CONCLUSION: To the best of our knowledge, this is the first report of persistent radial head instability because of an entrapped brachialis tendon.