Osteochondritis dissecans of the knee in a mummy from Northern Chile.

We report a case of osteochondritis dissecans (OCD) in a 4000 year old mummy from ancient Chile. This middle-age female specimen had characteristic bilateral medial femoral condyle erosions consistent with modern day presentations of OCD. The knee joints also demonstrated associated loose bodies of fairly similar dimensions and shape. OCD belongs to a group of disorders, the so-called osteochondroses, affecting the joints of the skeleton producing fragmentation, collapse, sclerosis as well as re-ossification and reconstitution of the articular surface. This case represents an interesting example of the natural history of untreated OCD and is also the earliest example of this thus far found in South America.