Humeral Head Bone Defects: Remplissage, Allograft, and Arthroplasty

The Hill-Sachs lesion is a well-known entity that threatens recurrent instability, but the treatment options are multiple and the surgical indications remain undefined. The evidence for each operative technique is limited to retrospective reviews and small case series without controls. The decision of which technique to use resides with the surgeon. Older, osteopenic patients, especially those with underlying arthritis and large defects, should be managed with complete humeral resurfacing. Humeralplasty is best used in younger patients with good quality bone in an acute setting with small- to moderate-sized bone defects. Partial resurfacing and remplissage are best used with small to moderate lesions, and both require further study. Allograft humeral reconstruction is an established technique for patients with moderate to large defects, and is best applied to nonosteopenic bone. Surgeons must be able to recognize the presence of humeral bone loss via specialized radiographs or cross-sectional imaging and understand its implications. The techniques to manage humeral bone loss are evolving and further biomechanical and clinical studies are required to define the indications and treatment algorithms.

Traumatic unidirectional glenohumeral joint instability is common and typically occurs in conjunction with labral or capsular injury; however, it can also be associated with bony lesions. Successful treatment requires recognition of all aspects of simple and complex instability to determine the most appropriate treatment algorithm. Management of glenohumeral instability includes nonoperative rehabilitation, soft-tissue repair or reconstruction, osseous reconstruction, or prosthetic replacement. This review outlines treatment options to restore or reconstruct osseous anatomy and shoulder stability in patients with humeral head bone defects.

In the nineteenth century, Flower and Broca and Hartmann described a posterior superior humeral head defect sustained after glenohumeral joint dislocation. In 1941, Hill and Sachs further described the eponymous lesion of humeral articular impaction that resulted from contact with the dense cortical bone of the anterior inferior glenoid rim during anterior subcoracoid dislocation. Palmer and Widén and Burkhart and DeBeer described an engaging Hill-Sachs lesion that occurs when the glenoid falls into the humeral head defect. To truly engage, the long axis of the humeral head defect must be parallel to the anterior glenoid rim with the arm in a position of abduction and external rotation. Engagement outside of this functional arc, with the arm at the side for example, is termed nonfunctional engagement or functionally nonengaging. If the humeral defect is not parallel to the glenoid rim, it may provide a sensation of subluxation when the lesion rolls over the anterior glenoid, but the rim will not fall into the defect and lever the humeral head from the glenoid socket.

Anterior inferior glenoid bone loss and engaging Hill-Sachs lesions have been implicated as factors leading to higher failure rates following soft-tissue stabilization procedures. Although osseous lesions are recognized factors associated with shoulder instability, there is little information describing surgical indications and optimal techniques to restore osseous anatomy and joint stability.

Epidemiology

Humeral head impression fractures are found in 65% to 71% of initial glenohumeral dislocations, and in up to 100% of patients with recurrent instability. A correlation between the presence of humeral head lesions and bony Bankart lesions exists and increases with recurrent instability. In a study of 61 patients, Widjaja and colleagues found that after a first dislocation, 64% of patients with a bony Bankart lesion also had a Hill-Sachs, and 70% of those with a Hill-Sachs lesion also had a Bankart lesion. Seventy-nine percent of patients with recurrent instability and a bony Bankart lesion also had a Hill-Sachs, and 81% of those with a Hill-Sachs had a bony Bankart lesion.

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