[Forefoot plantar pressure changes of the first tarsometatarsal joint fracture-dislocation fixation by different internal fixations].

OBJECTIVE

To measure the changes of plantar pressure of the first tarsometatarsal joint fracture and 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 and dislocation, which were fixed with 3.5 mm cortical screw, 1/4 tubular plate and compressive staple in turn. After the loading of 600 N, 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 and dislocation, the peak pressure under the first metatarsal head would decrease, while the pressure under the second metatarsal head would increased,whose differences were statistically significant (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 showed the statistical significant difference compared with normal state, although the peak pressure under the first and second metatarsal heads were recovered in some extent(P<0.05).

CONCLUSION

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