Posterior ossification of the shoulder: the Bennett lesion. Etiology, diagnosis, and treatment.

We report a series of ossific lesions of the posterior inferior glenoid in a group of elite baseball players. We hope to clarify the etiology, diagnosis, and treatment of the Bennett lesion. From August 1985 to August 1991, we identified six professional baseball pitchers and one college pitcher with evidence of ossification of the shoulder on plain radiographs, computed tomography, or magnetic resonance imaging. Arthroscopic examination was performed in all cases. All seven players had identifiable posterior labral injury on arthroscopic examination; six of these seven also had varying degrees of undersurface posterior rotator cuff damage. No anterior tissue damage, anterior instability, or subacromial impingement was noted. No ossification was identified arthroscopically. Intraarticular labral and rotator cuff tears were debrided arthroscopically and patients underwent rehabilitation for 4 to 6 months after surgery. Six of the seven athletes returned to preinjury performance levels; however, one pitcher is no longer playing competitive baseball. The Bennett lesion is an extraarticular posterior ossification associated with posterior labral injury and posterior undersurface rotator cuff damage. It is not, however, a result of traction stresses in the region of the triceps insertion. Recognition is important for identification and treatment of the lesion and associated pathologic damage.