[Static anterior glenohumeral subluxation following coracoid bone block in combination with pectoralis major transfer: a case report and biomechanical considerations].

We report the case of a patient who experienced post-traumatic static anterosuperior subluxation of the shoulder. The displacement worsened after surgical treatment associating a preglenoid bone block and pectoralis major transfer. We studied the lines of action of the conjoint tendon on an anatomic model. The biomechanical study demonstrated that alone, the coracoid bone block did not provoke the anterior glenohumeral subluxation. On the contrary, the compression components of the humeral head into the glenoid cavity increased and could not explain the worsening dislocation. Inversely, the tendon of the pectoralis major passed in front of the conjoint tendon because of the absence of the subscapularis and could have been the cause of the aggravated anterior subluxation.