All shoulder dislocations cause some amount of bone damage. In the most common type of dislocation, the head of the humerus (upper arm bone) is forced forward and out of the shoulder socket. This is known as an anterior shoulder dislocation.
Even if the shoulder is reduced (head of the humerus is put back in the socket), the soft tissues around the shoulder have been overstretched. If the humeral head hits the rim of the socket with enough force, there can be damage to both areas (the humeral head and the glenoid rim). This type of injury is referred to as a Hill-Sachs lesion.
Studies show that there is always some amount of bone damage with a first-time anterior dislocation. If the defect is moderate-to-severe, the loss of bone results in abnormal shoulder motion (biomechanics). Many patients develop recurrent shoulder instability meaning the shoulder dislocates over and over.
Orthopedic surgeons treating patients with Hill-Sachs lesions and chronic shoulder instability must understand the relationship between these two events. Formulating a successful treatment plan depends on the surgeon’s recognition (and treatment of) any humeral bone loss. That’s why these two surgeons from the University of Michigan are revisiting this problem and reviewing the diagnosis and management of humeral head bone loss in shoulder instability.
They suggest it may not be enough to repair the torn or damaged soft tissues (tendons and ligaments) if there is also a bony defect. The soft tissue repair or reconstructive surgery is more likely to fail if the bony lesion(s) are not addressed as well. They point out that an engaging Hill-Sachs defect (the bone defect catches on the glenoid rim during shoulder motion) must be identified and treated as well.
Using drawings to depict the problems and CT scans and photos of the lesions, these surgeons review all of the reconstructive procedures currently available to treat Hill-Sachs lesions. They provide tables to summarize anatomic and nonanatomic techniques. Pros and cons of each procedure are listed. Postoperative problems and complications are reviewed as well. Special considerations for overhead throwing athletes with this type of injury are also mentioned.
Anatomic repair (putting everything back the way it was meant to be) is always preferred. But a nonanatomic approach (e.g., using bone grafts, removing the humeral head, shoulder replacement) may be necessary in cases where there is more severe damage. The authors describe situations where each type of procedure might be considered. Patient age, activity level, severity of injury, and bone quality are some of the factors that must be evaluated when determining the best plan of care for each individual.