Force Generation of the Hallux is More Sensitive to the Ankle and Metatarsophalangeal Joint Angle Than the Lesser Toes

Background: Because the structure of the hallux is independent of that of the lesser toes and it uses different muscles to move, the force generation characteristics of the hallux could be independent of those of the lesser toes. The purpose of this study is to clarify the torque–angle relationships in the first and second–fifth metatarsophalangeal joints (MTPJs).Methods: Ten healthy young men served as volunteers in this study. The maximal voluntary contraction (MVC) of the plantar-flexion torques of the first and second–fifth MTPJs were measured at 0°, 15°, 30°, and 45° dorsiflexed positions of the MTPJs and 20° plantar-flexed, neutral, and 20° dorsiflexed positions of the ankle. The Friedman test and the Wilcoxon signed-rank test with a Holm correction was used for the ankle and MTPJ angles.Results: When the first MTPJ was 0° to DF30°, the MVC torque of the first MTPJ at DF20° of the ankle was higher than at PF20°of the ankle. On the other hand, no significant difference existed between the MVC torques of the second–fifth MTPJs at any ankle position. When the ankle was in a neutral position, the MVC of the first MTPJ torque increased as the MTPJ was dorsiflexed. However, the MVC torques of the second through fifth MTPJs did not significantly differ for the 15°, 30°, and 45° dorsiflexed positions of the MTPJ.Conclusion: The MVC torque of the first MTPJ is more sensitive to the MTPJ and ankle positions than the second–fifth MTPJs.