Osteonecrosis of the Femoral HeadMatthew OrtonRadiology Presentation7/20/2007

HPIA 20 yo male with SLE reports to ER complaining of chronic L hip pain and new L knee pain that has not resolved since fall 1 week ago.PCP diagnosed SLE in 2004.Meds: Lisinoprol, Prednisone, Zantac, HCTZ, Imuran, Volteran,

Sclerosis and density changesCrecent Sign = subcondral radiolucancy

Loss of smooth spherical or collapse of femoral head. Joint space narrowing , degenerative changes.

MRI of Femoral Head OsteonecrosisCoronal T1 MRI of both hips shows diffuse low signal throughout the left femoral head, neck, and proximal shaft.

Axial T2 MRI of both hips shows diffuse high signal in the left femoral head consistent with the avascular necrosis.

Images from: brighamrad.harvard.edu

Osteonecrosis of Femoral HeadOsteonecrosis = aseptic necrosis, avascular necrosis, ischemic necrosis and osteochondritis dessicans. Mechanism compromise of bone vasculature leading to death of bone and marrow cells and ultimately mechanical failure. Process is often progressive and results in joint destruction in 3-5 years if untreated.

Exact pathogenesis still under debated. Some theories include intravascular necrosis, increased intraosseous pressure, mechanical stresses, or metabolic factors. Prevalence is 10,000-20,000 cases diagnosed in US/year. M:F = 8:1. 5% of patients with SLE will develop osteonecrosis. Staging

Stage 0 All diagnostic studies normal, diagnosis by histologyStage 1 Plain radiographs and computed tomography normal, magnetic resonance imaging positive and biopsy positive. Stage 2 Radiographs positive but no collapse. Stage 3 Early flattening of dome, crescent sign, computed tomography or tomograms may be needed.Stage 4 Flattening of femoral head with joint space narrowing, possible other signs of early osteoarthritis

NontraumaticCorticosteroidSickle cell Systemic lupus erythematosusGauchers DiseaseChronic renal failure or hemodialysisRadiationExcessive ETOH

TraumaticFemoral Neck FractureFemoral Dislocation

Treatment of Osteonecrosis of Femoral Head Conservative management ( rest and pain control) if

ReferencesDonohue, JP.UptoDate: Osteonecrosis (avascular necorsis of bone). 2007.Jones LC, Hungerford DS. Osteonecrosis: etiology, diagnosis, and treatment. Curr Opin Rheum 2004; 16: 443-449.Galindo M, Mateo I, Pablos JI. Multiple avasular necrossis of bone and polyarticular septic arthritis in patients with systemic lupus erythematosus. Rheumatol Int 2005; 25: 72-76.