Osteochondral disruption of the second metatarsal: a variant of Freiberg's infraction?

A case of Freiberg's Infraction of the second metatarsal is presented. The metatarsal head was resected and its pathology proved very informative. Necrotic bone was not found, but a shearing type of separation was identified at the level of "tidewater mark" in the articular cartilage and was the major observation. This suggested the possibility that in adults Freiberg's Infraction rather than true avascular necrosis may be in fact the result of a shearing-compression type of injury occurring at the interface between mineralized and nonmineralized articular cartilage (tidewater mark). An anatomical examination of metatarsophalangeal joints in cadavers showed that during walking at the "toe off" position, the toes dorsiflex to force the metatarsal head into plantar flexion. The proximal phalanges ride dorsally over the metatarsal heads producing a shearing force that would support our interpretation of the observations made in the case presented.