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What’s the Diagnosis?

Case of the Month

The New Physician March-April 2014

A Young Boy with Left Knee Pain

The case below is followed by a choice of diagnoses. Select the answer choice that best describes this patient’s condition.

A 7-year-old boy presents to the ED with a two-day history of left hip and knee pain and refusal to bear weight on the left leg after falling down. His mother reports no laceration, abrasion, or bruising; the boy denies any numbness or tingling but describes the pain as mild to moderate. On further questioning, his mother describes a two-month history of worsening limp, decreasing mobility, and increasing left hip and knee pain, without any known trauma. The boy also visited the ED 10 months ago for similar complaints; radiography showed mild unilateral left-sided juvenile Blount disease. He was discharged on NSAIDs and was asymptomatic after three days and for the next eight months.

The boy uses an albuterol inhaler for intermittent asthma episodes; his past medical and family histories are otherwise noncontributory.

On physical examination, the patient has a temperature of 98.2°F (36.8°C), pulse of 82 beats/min, blood pressure of 138/74 mm Hg, respiratory rate of 19 breaths/min, and an oxygen saturation of 99% on room air. The patient is markedly obese at 181 lbs. (82 kg). His neurovascular examination is normal. There is decreased range of motion (ROM) of both the left hip, with pain on passive internal rotation while lying supine, and the left knee; the left groin and left knee are tender to palpation. No swelling, laxity, or effusion is noted. The left ankle, foot, and other extremities are unremarkable. The boy refuses to bear weight on his left leg and demonstrates an antalgic gait.

Frontal knee radiographs (not shown) reveal abnormal medial metaphyseal beaking of the left proximal tibia and mild medial epiphyseal flattening; there is no significant change in the left-sided juvenile Blount disease from the previous radiographs. However, comparison of the current left hip radiographs and those obtained 10 months ago (not shown) reveal an interval change (Figures 1 and 2).

What is the diagnosis?


The peak age for this diagnosis is 4–8 years.

A. Septic arthritis

B. Transient synovitis

C. Legg-Calvé-Perthes disease

D. Slipped capital femoral epiphysis

Go to the answer page


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