Avascular Necrosis of the Humeral Head: Hemi-Cap, Cap, or Stemmed Solution?

Avascular necrosis of the humeral head, as in other joints, can have a spectrum of severity. The degree of humeral head involvement should dictate the degree of prosthetic replacement required to restore congruity and function. In some very early phases of disease, observation or core decompression and supportive bone grafting may be considered. This article will focus on management of later problems where articular subsidence, degeneration, and arthrosis have dictated the need for varying degrees of prosthetic replacement. With a focal area of necrosis and collapse, but maintenance of peripheral articular congruity and subchondral support, a central core articular humeral replacement can be performed using a focal surface replacement or “hemi-cap” implant. For more global surface degeneration with maintenance of a relatively healthy surrounding subchondral bone support, total resurfacing of the articular surface can provide a seamless means of restoring congruity without burning the bridges of complete humeral head excision. When advanced, collapse occurs, and there is not enough supportive bone to provide foundation for a resurfacing implant, a stemmed implant should be considered. When biarticular disease ensues, following humeral head collapse and erosion of the glenoid, more formal total shoulder arthroplasty resurfacing is needed. The approach that will be presented here uses a “straightforward minimalist” conservative approach to the replacement of only the diseased articular surface with preservation of as much bony architecture as possible. This approach provides the surgeon with a process to restore articular congruity while at the same time preserving all viable bony architecture. In young patients, this is important when considering the long-term prospect of the need for future revision surgery.