A right-handed 53-year-old man presented with a subcutaneous bruise on his right shoulder caused by a seatbelt during a traffic accident. He had no history of shoulder pain or hydrocortisone injections. The contour of the anterior deltoid was deformed and its belly was retracted distally. The active range of movement of the shoulder was limited to 120 degrees and the strength weakened to 3/5. Magnetic resonance imaging demonstrated detachment of the anterior fibres of the deltoid. Surgical repair of the deltoid and supraspinatus tendon was performed 2 months later using a pull-out suture technique. After 12 months of follow-up, the patient had returned to work without any problems. Both the range of movement and muscle strength had recovered completely.