The biomechanical study of the influence to the forefoot plantar pressure of the first tarsometatarsal joint fracture-dislocation fixed by three different implants

Objectives: To study the influence of forefoot plantar pressure of the first tarsometatarsal joint fracture-dislocation by three different implants to provide experimental reference in selecting implants.

Methods: Eight fresh foot specimens were made into the models of the first tarsometatarsal joint fracture-dislocation, which were fixed with 3.5 mm cortical screw, 1/4 tubular plate and compressive staple in turn. After the loading of 600N, the changes of the plantar pressure in forefoot were measured by the method of the F-scan plantar pressure system.

Results: After first tarsometatarsal joint fracture-dislocation, the peak pressure under the first metatarsal head would decrease, while the pressure under the second metatarsal head would increase(P<0.05). When the first tarsometatarsal joint was fixed with screw or plate respectively; the peak pressure under the two metatarsal heads would tend to be normal. However, the staple fixation would show the statistical significant difference, although the peak pressure under the first and second metatarsal heads were recovered in some extent (P<0.05).

Conclusions: After the first tarsometatarsal joint fracture-dislocation, the plantar pressure might be compensated partly by the adjacent metatarsal heads. While the first tarsometatarsal joint fracture-dislocation was fixed by screw or plate, the plantar pressure of the forefoot would return to the normal state. However, if the joint was fixed by the staple, it would still be difficult to return the plantar pressure to be normal.