Volcanic knee

Abstract

In December, 2009, a 24-year-old man presented to us with a painful, hot, right knee. He had had similar episodes for the past 10 years. He could not recall any precipitating factor. On previous occasions by the time he had sought medical attention, his symptoms had resolved. A self-limiting inflammatory arthropathy had been suspected, and he had never been aggressively investigated. He learnt to tolerate what he called his “volcano knee” because of its tendency to erupt, and then lie dormant for months or years. Our patient's temperature was 38·1°C and C-reactive protein was 189 mg/L. A plain radiograph showed a sclerotic-rimmed lesion in the distal femur (figure A). Frank pus was aspirated from the joint. He had an arthroscopic lavage of the knee, and intravenous antibiotics were started. Meticillin-sensitive Staphylococcus aureus was isolated from the knee aspirate and blood culture. (A) CT (coronal) of right knee, showing sclerotic lesion in distal femur (arrows). (B) Gadolinium enhanced MRI (sagittal) of the right distal femur.