Osteochondrosis juvenilis is caused by a dysfunction of endochondral ossification. Several epiphyses and apophyses can be affected, but osteochondrosis juvenilis of the medial malleolus has not been reported. We describe a 12-year-old boy with bilateral pes planovalgus who was affected by this condition. Conservative management was successful. The presentation, aetiology and treatment are described and the importance of including it in the differential diagnosis is discussed.

Introduction and Aims: The possible deleterious effects of long distance running remain controversial. The repetitive loading could potentially predispose to the subsequent development of osteoarthritis. The purpose of this study is to investigate whether external impact loading in marathon runners creates internal stresses on bone and cartilage that are demonstrable on MR images.

Method: Six recreational, two semi-professional runners and seven beginners underwent magnetic resonance (MR) imaging of the hip and knee before and after a marathon run using coronal body phased-arrayed coil and the following pulse sequences: a coronal T1 weighted spin echo sequence and STIR sequences. To be included in the study, the runners had to successfully finish a previous race in less than 4.5 hours. The following exclusion included surgery for overuse injuries in the prior 48 months, and symptoms of overuse in the six months preceding the race.

Results: The pre- and post-run scans failed to demonstrate marrow oedema, periosteal stress reactions or joint effusions in seven runners. One patient who underwent a reconstruction of his anterior cruciate ligament 18 months ago demonstrated a small effusion in the reconstructed knee before and after the race. Six of the beginners demonstrated minimal effusions in the hip and knee joints. However no bone oedema was seen in any of the beginners.

Conclusions: Our results suggest that the high impact forces in long distance running are well tolerated and subsequently not demonstrated on MR images in experienced runners. Beginners do compensate the impact stresses to a certain extend and it is postulated that long distance runners undergo a natural selection process.