Question 1

How does shoulder AVN differ from hip AVN? Are the treatments and outcomes the same?

Accepted Answer

Shoulder AVN is LESS COMMON and has DIFFERENT outcomes compared to hip AVN. INCIDENCE: Hip AVN 10-20x more common than shoulder (hip is weight-bearing joint, higher mechanical stress). Shoulder AVN represents 5-10% of all AVN cases. CAUSES: Hip AVN - glucocorticoids (40%), alcohol (30%), idiopathic (20%), trauma (10%). Shoulder AVN - trauma (40%, especially 3-4 part proximal humerus fractures), glucocorticoids (30%), idiopathic (20%), alcohol (10%). PROGRESSION RISK: Hip AVN - 80-90% progress to collapse without surgery (high risk due to weight-bearing). Shoulder AVN - 60-70% progress to collapse (lower than hip - non-weight-bearing joint). CORE DECOMPRESSION OUTCOMES: Hip - 60-80% success Ficat I-II preventing collapse. Shoulder - 40-60% success (LOWER than hip, less blood supply, smaller bone volume). ARTHROPLASTY OUTCOMES: Hip replacement - 90-95% excellent outcomes, 15-20 year survival >90% (very successful). Shoulder hemiarthroplasty - 70-80% good outcomes, glenoid erosion 20-30% requiring revision (LESS successful than hip, metal-on-cartilage wear issue). Reverse shoulder - 80-90% pain relief but limited external rotation (functional compromise). BOTTOM LINE: Shoulder AVN is less common, progresses slower, and has WORSE surgical outcomes than hip AVN. Core decompression less successful for shoulder (40-60% vs 60-80% hip). Shoulder replacement outcomes inferior to hip replacement (70-80% vs 90-95%, higher complication rates). Non-weight-bearing nature of shoulder is advantage (slower progression) but smaller humeral head size limits surgical options.

Question 2

If I'm on long-term prednisone for lupus/rheumatoid arthritis, what's my risk of developing AVN and can I prevent it?

Accepted Answer

GLUCOCORTICOID-ASSOCIATED AVN RISK: DOSE-DEPENDENT: Prednisone <10mg/day: <1% AVN risk (very low). Prednisone 10-20mg/day: 3-5% AVN risk (moderate). Prednisone >20mg/day: 10-15% AVN risk (high - especially if >3 months duration). Pulse dosing (high-dose IV methylprednisolone): 5-10% AVN risk even if short-term. CUMULATIVE DOSE MATTERS: Total prednisone >2 grams doubles AVN risk. Example: 20mg daily for 4 months = 2.4 grams (high risk). MECHANISM: Glucocorticoids cause fat cell hypertrophy → increased bone marrow pressure → venous stasis → ischemia. Lipid metabolism disruption → fat emboli occlude small vessels. TIME TO AVN ONSET: 80% develop AVN within first 12 months of steroid therapy. Median time to symptoms: 6-18 months after starting high-dose steroids. PREVENTION STRATEGIES: (1) MINIMIZE DOSE & DURATION - Use lowest effective prednisone dose (goal <10mg/day if possible). Taper as quickly as medically safe. Switch to steroid-sparing agents early (methotrexate, azathioprine, biologics for RA/lupus). (2) LIPID-LOWERING THERAPY - Statins may reduce AVN risk by 40-50% (limited evidence - Chinese studies suggest benefit). Mechanism: reduce lipid emboli formation. (3) BISPHOSPHONATES - Some evidence alendronate reduces progression Ficat I → III (conflicting data). Not standard prevention. (4) ANTICOAGULATION - No proven benefit (AVN is thrombotic/embolic but anticoagulation doesn't prevent). (5) EARLY MRI SCREENING - Consider baseline MRI hips/shoulders if starting high-dose steroids (>20mg >3 months). Repeat MRI if new joint pain develops (allows Ficat I-II diagnosis when joint-preserving surgery possible). BILATERAL SCREENING: If AVN diagnosed one joint, 60-80% have asymptomatic contralateral AVN - bilateral MRI mandatory. BOTTOM LINE: If you require long-term prednisone, work with rheumatologist to minimize dose (<10mg target), use steroid-sparing agents aggressively, consider statins, and report any new joint pain immediately for early MRI (early diagnosis = better treatment options). Absolute prevention not possible if high-dose steroids medically necessary, but risk reduction strategies exist.

Medical Disclaimer

Avascular Necrosis of the Humeral Head

📖What is Avascular Necrosis of the Humeral Head?

🔬What Causes It?

⚠️Risk Factors

You may be at higher risk if:

🛡️Prevention