Osteonecrosis of the femoral head / Legg-Calvé-Perthes disease
“A 7-year-old female is brought to your office with a complaint of right hip pain and a limp with an insidious onset. There is no history of injury or repetitive use. Her vital signs are within normal limits and she has no history of fever or chills or other systemic symptoms. On examination you note that she cannot fully abduct her hip and she winces with pain on internal rotation. A FABER test is normal. Her right leg is 2 cm (¾ in) shorter than the left. Plain films reveal flattening and sclerosis of the proximal femur with joint space widening. What is the most likely diagnosis in this patient?
DDx
Legg-Calvé-Perthes disease results from interruption of the blood supply to the still-growing femoral head. It occurs in children 2–12 years of age and presents with hip pain and an atraumatic limp. Common physical findings include leg-length discrepancies, and limited abduction and internal rotation. Radiographs reveal sclerosis of the proximal femur with joint space widening. MRI confirms osteonecrosis. Septic arthritis also causes atraumatic anterior hip pain but occurs in the acutely ill, febrile patient. A CBC, erythrocyte sedimentation rate, C-reactive protein level, and guided hip aspiration are recommended if septic arthritis is suspected. A diagnosis of stress fracture should be considered in patients with a history of overuse and weight-bearing exercise. These patients have pain that is worse with activity, and pain on active leg raising. MRI can detect fractures not seen on plain films. Iliopsoas bursitis presents with snapping or popping of the hip on extension from a flexed position. Labral tears present with sharp anterior hip pain at times, with radiation to the thigh or buttock. Usually patients will have mechanical symptoms such as clicking with activity. The FABER (flexion, abduction, external rotation) and FADIR (flexion, adduction, internal rotation) impingement tests are sensitive for labral tears.
Atanda A Jr, Shah SA, O’Brien K: Osteochondrosis: Common causes of pain in growing bones. Am Fam Physician 2011;83(3):285-291. 2) Wilson JJ, Furukawa M: Evaluation of the patient with hip pain. Am Fam Physician 2014;89(1):27-34.
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