Osteonecrosis

Populations and Risk Factors

Adults aged 20-50 (peak incidence in the 30s and 40s)
Men affected more frequently than women (approximately 3:1 ratio)
Long-term corticosteroid use (most common non-traumatic cause — fat cell hypertrophy compresses sinusoidal vessels)
Excessive alcohol consumption (second most common non-traumatic cause)
History of hip fracture or dislocation (traumatic disruption of blood supply)
Sickle cell disease (vaso-occlusive crises block blood flow to bone)
SLE and other autoimmune conditions requiring steroid therapy
Radiation therapy, organ transplant recipients, decompression sickness (divers)
Idiopathic in approximately 20% of cases
Bilateral involvement in 50-80% of non-traumatic cases

Traumatic: Femoral neck fracture or hip dislocation physically disrupts the retinacular arteries supplying the femoral head
Corticosteroid-induced: Corticosteroids cause fat cell hypertrophy in marrow, compressing sinusoidal vessels and reducing blood flow. Also associated with fat embolism to subchondral vessels
Alcohol-induced: Promotes fatty infiltration of marrow and fat embolism, impairing microcirculation
Ischemic cascade: Bone tissue deprived of blood undergoes ischemic necrosis within hours to days. Dead bone initially maintains structural integrity but cannot undergo normal remodeling
Structural failure: Over weeks to months, osteoclast resorption at the necrotic-viable bone interface weakens the subchondral plate. Subchondral fracture (crescent sign on X-ray) marks the point of structural failure
Secondary OA: Progressive collapse of the articular surface leads to secondary osteoarthritis of the joint

May be asymptomatic in early stages (often discovered incidentally on MRI)
Insidious onset of deep, aching groin or hip pain, aggravated by weight-bearing
Pain may radiate to the buttock, thigh, or knee
Progressively restricted range of motion, especially internal rotation and abduction (capsular pattern of the hip)
Antalgic gait (limping to avoid loading the affected hip)
In later stages: constant pain, even at rest, with significant functional limitation
Red flags: Unexplained groin or hip pain in a client taking corticosteroids warrants medical referral before proceeding with treatment; bilateral hip pain in a young adult should raise suspicion for AVN

CMTO Appendix category A1 (MSK conditions)
Key concept: insidious hip/groin pain in a client on long-term corticosteroids should raise suspicion for AVN
Bilateral involvement is common — always assess both hips
Recognize the crescent sign on X-ray as indicating subchondral fracture and structural failure
MRI is the gold standard for early detection (before X-ray changes appear)
Differentiate from osteoarthritis (gradual onset, older population) and hip labral tear (mechanical clicking)

Relative contraindication: Massage to the affected limb requires medical clearance and careful pressure modification
Avoid: Deep pressure, joint mobilization, or vigorous stretching of the affected hip — the femoral head may be structurally compromised
Goal: Pain management, reduction of compensatory muscle tension (hip flexors, adductors, lumbar paraspinals, contralateral hip)
Safe approach: Gentle effleurage and petrissage to surrounding muscles. Address compensatory patterns in the lumbar spine and contralateral lower extremity
Post-surgical (core decompression or arthroplasty): Follow surgeon's rehabilitation protocol. Massage supports recovery of surrounding soft tissue
Positioning: Avoid positions that load the affected hip (excessive flexion, internal rotation)

Osteonecrosis is death of bone tissue from disrupted blood supply, most commonly affecting the femoral head
Corticosteroid use and alcohol consumption are the leading non-traumatic causes. Femoral neck fracture is the leading traumatic cause
The condition is often bilateral (50-80% of non-traumatic cases) and may be asymptomatic early, progressing to joint destruction without intervention
MRI is the gold standard for early detection. The crescent sign on X-ray indicates subchondral collapse
Massage therapy is a relative contraindication — avoid deep pressure or mobilization of the affected joint. Focus on compensatory muscle tension and pain management