We report the case of a patient who sustained a missed locked posterior shoulder dislocation with a sizable anterior impression fracture and a concomitant acute rupture of the subscapularis tendon. Despite compromise of the tendon, a transfer of the lesser tuberosity into the humeral head defect along with suture anchor repair of the subscapularis was performed. Within 6 months, the patient regained near complete function of his shoulder with no episodes of instability. To our knowledge, this is the first reported case of an acute subscapularis rupture associated with a posterior shoulder dislocation and anterior humeral impression fracture, treated with the modified McLaughlin procedure and tendon repair with an excellent clinical result.