Computer evaluation of second tarsometatarsal joint dislocation

Using computer-assisted techniques, this study analyzes the mean contact area of the articular surface of the second tarsometatarsal joint. The articular contact area decreased proportionate to the displacement in both males and females, but it was consistently greater in males than in females for all simulated displacements. The reduction in the contact area was the highest with dorsolateral displacement compared with the lateral and dorsal displacements. Dorsolateral displacement of the second metatarsal of 3 mm led to 38.6% reduction in the contact area, compared with 33.1% and 20.2% reduction with lateral and dorsal displacements, respectively. This study shows that even minor degrees of displacement not apparent on plain radiographs lead to significant decrease in the contact area of the second tarsometatarsal joint. Careful evaluation of second tarsometatarsal injuries with computed tomography is recommended to detect minor degrees of displacement.