Humeral head avascular necrosis: etiology, diagnosis, and management.

Humeral head avascular necrosis (AVN) can cause significant shoulder morbidity and represents the second most common site of nontraumatic osteonecrosis after the femoral head. The pathophysiology centers on disrupted blood supply, ultimately leading to bone death and structural compromise. It is associated with various etiologies, including trauma, iatrogenic factors, hematologic conditions, lifestyle factors, certain environmental exposures, and systemic diseases. Diagnosis relies on a combination of clinical assessment and radiographic evaluation, with magnetic resonance imaging serving as the most sensitive modality for early detection. The Cruess classification system guides treatment decisions. Although conservative measures are used in early stages, they carry a risk of progression, as they do not alter the disease course-unlike surgical techniques such as core decompression. Arthroplasty is reserved for later stages with evidence of collapse, with research suggesting that the use of pyrocarbon in hemiarthroplasty may help reduce glenoid erosion. This review provides a comprehensive overview of humeral head osteonecrosis, emphasizing its etiology, clinical evaluation, imaging findings, and treatment strategies. It highlights the growing support for early operative intervention over conservative management, emerging treatment modalities such as biologic augmentation and allografting, and promising new materials like pyrocarbon in hemiarthroplasty to mitigate glenoid erosion.