Module 71, General Orthopaedist Level

This 9 year old female presented to the emergency room with a four day history of mild right knee pain. She limps on the affected extremity when ambulating but has minimal to no pain at rest. There is no history to suggest trauma. She apparently has had mildly elevated temperatures over the last several days according to the mother. There is no history of joint stiffness or chronic fatigue. No other joints are involved. There is no history of tick exposure. She has been otherwise healthy in the past. On physical examination of the right knee there is no limitation in flexion or extension. There is mild diffuse tenderness that is poorly localized over the medial femoral condyle. There is no soft tissue swelling or joint effusion noted. No pain is elicited with ROM of the knee. The remaining extremities are without tenderness or swelling. Temperature was 38.3 C. An xray of the knee was found to be normal. The laboratory test included, WBC 13400, Differential: 73% polys, 8% lymphs, 1% bands, and Sedimentation rate 41mm/hr.

Question 71A

The child can be started on oral cephlathin and discharged home with a follow-up in 24 hours.

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Question 71B

The child is seen the next day when the temperature is 39.5 and the child feels more ill. The knee examination is unchanged. The next test to obtain is an MRI scan of the knee.

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Question 71C

The following day the Lyme titer returns in the normal range which rules out Lyme's disease as the cause of the current problem.

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Question 71D

The area of tenderness suggests that is not likely to be osteomyelitis which occurs in the metaphyseal region of the bone.

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Question 71E

The above laboratory tests, history and physical examination suggest that this may be rheumatoid arthritis.

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