Avascular Necrosis of the Humeral Head: Evaluation and Management
Start with plain radiographs (AP, lateral, oblique views) to exclude other pathology, then proceed immediately to MRI for definitive diagnosis and staging, as radiographs miss early disease but are essential for ruling out fracture, tumor, and arthritis 1.
Initial Diagnostic Approach
Imaging Algorithm
- First-line: Radiography of the shoulder - While less sensitive for early AVN, radiographs are critical to exclude alternative diagnoses (fracture, primary arthritis, tumor) and identify late-stage disease with collapse or secondary osteoarthritis 1
- Second-line: MRI - This is the definitive diagnostic modality. Bone scintigraphy has been replaced by MRI due to poor spatial resolution, low specificity, and inability to quantify necrotic lesion size 1
Critical Prognostic Assessment
Measure the necrotic angle on mid-coronal MRI plane - This is the single most important prognostic factor:
- Necrotic angle <90°: Did not collapse over 24 months of follow-up 1
- Necrotic angle ≥90°: High risk for progression to collapse 1
Additional poor prognostic indicators include:
- Age >40 years
- Increased joint effusion
- Increased bone marrow edema surrounding the necrotic focus
- BMI >24 kg/m² 1
Risk Factor Identification
Common causes to evaluate: corticosteroid therapy, alcohol use, trauma, HIV, lymphoma/leukemia, blood dyscrasias, chemotherapy, radiation therapy, Gaucher disease, Caisson disease 1. Screen for bilateral hip involvement (70-80% in nontraumatic cases) and multifocal disease - shoulder AVN occurs in 15% of steroid-treated patients with osteonecrosis 1.
Management Algorithm
Early-Stage Disease (Pre-Collapse)
Initial management should be nonoperative with risk factor modification, physical therapy, NSAIDs, and activity modification 2, 3. This is particularly effective in younger patients, with recent data showing normative functional scores at 7-year follow-up in pediatric/young adult populations 3.
Noninvasive Options (Limited Supporting Data)
The evidence for these remains weak 1:
- Statins
- Bisphosphonates
- Anticoagulants
- Extracorporeal shock wave therapy
- Hyperbaric oxygen
Joint-Preserving Surgery (Controversial Efficacy)
Core decompression with or without augmentation (bone marrow cells, vascularized fibular grafting, electrical stimulation) can be considered for early-stage disease, but efficacy at preventing eventual collapse remains controversial 1. The decision should weigh:
- Necrotic angle measurement
- Patient age and activity demands
- Willingness to accept uncertain benefit
Common pitfall: Proceeding with core decompression in large lesions (necrotic angle ≥90°) where collapse is nearly inevitable.
Late-Stage Disease (Post-Collapse)
When articular collapse has occurred, arthroplasty becomes necessary 1.
Arthroplasty Selection
For isolated humeral head collapse with preserved glenoid and intact rotator cuff, hemiarthroplasty is superior to total shoulder arthroplasty - A 2026 meta-analysis demonstrated HA yields significantly higher ASES scores (MD 17.12, P<0.00001) and lower complication rates (RR 0.33, P<0.0001) compared to TSA 4. TSA provides only marginally better external rotation (10.23°) 4.
Choose hemiarthroplasty when:
- Glenoid cartilage is preserved or minimally involved
- Rotator cuff is intact (confirm with preoperative ultrasound or MRI) 5
- Patient is younger with future revision considerations 5
Choose total shoulder arthroplasty when:
- Secondary glenohumeral arthritis is established
- Glenoid bone stock is adequate
- External rotation is a critical functional goal 4
Choose reverse shoulder arthroplasty when:
- Rotator cuff is deficient or torn
- Acromiohumeral interval <7mm (indirect sign of cuff dysfunction) 6
- Greater tuberosity shows complete resorption 6
Critical caveat: The traditional recommendation for TSA in AVN should be reconsidered given recent comparative data favoring HA in appropriate candidates 6, 4.
Staging Systems
Multiple systems exist (Ficat-Arlet, Steinberg, ARCO, Japanese Orthopedic Association), with Ficat-Arlet remaining most commonly used despite not accounting for lesion size or location 1. Use staging primarily for communication and surgical planning, but base treatment decisions on necrotic angle measurement and presence of collapse.
Key Clinical Pearls
- Early diagnosis matters - It excludes other pain causes and potentially allows joint-preserving intervention before collapse 1
- Pain is the presenting symptom in 95% of cases 3
- Most shoulders are Stage II at diagnosis 3
- 55.6% ultimately require surgery despite initial nonoperative management 3
- Implant survival is 88% with 19% complication/revision rate for arthroplasty 6