Brigham Young University, Provo, UT, 84602, USA.
University of Delaware, Newark, DE, 19716, USA.
J Foot Ankle Res. 2023 Jul 25;16(1):44. doi: 10.1186/s13047-023-00643-x.
Kinematic coupling between the first metatarsophalangeal (MTP) and midtarsal joints is evident during gait and other movement tasks, however kinetic foot coupling during walking has not been examined. Furthermore, contributing factors to foot coupling are still unclear. Therefore, the purpose of this study was to investigate kinematic and kinetic coupling within the foot by restricting MTP motion during overground walking. We hypothesized that when the MTP joint was prevented from fully extending, the midtarsal joint would achieve less peak motion and generate less positive work compared to walking with normal MTP motion.
Twenty-six individuals participated in this randomized cross-over study. Using motion capture to track motion, participants walked at 1.3 m/s while wearing a brace that restricted MTP motion in a neutral (BR_NT) or extended (BR_EX) position. Additionally, participants walked while wearing the brace in a freely moveable setting (BR_UN) and with no brace (CON). A pressure/shear sensing device was used to capture forces under each foot segment. During stance, peak joint motion and work were calculated for the MTP and midtarsal joints using inverse dynamics. A series of ANOVAs and Holm post hoc tests were performed for all metrics (alpha = 0.05).
The brace successfully decreased peak MTP motion by 19% compared to BR_UN and CON. This was coupled with 9.8% less midtarsal motion. Kinetically, the work absorbed by the MTP joint (26-51%) and generated by the midtarsal joint (30-38%) were both less in BR_EX and BR_NT compared to BR_UN.
Implications and sources of coupling between the MTP and midtarsal joints are discussed within the context of center of pressure shifts and changes to segmental foot forces. Our results suggest that interventions aimed at modulating MTP negative work (such as footwear or assistive device design) should not ignore the midtarsal joint.
在步态和其他运动任务中，第一跖趾（MTP）和中跗关节之间存在运动学耦合，但在行走过程中尚未检查到足的运动学耦合。此外，足耦合的影响因素仍不清楚。因此，本研究的目的是通过限制地面行走中的 MTP 运动来研究足的运动学和运动学耦合。我们假设当 MTP 关节不能完全伸展时，与 MTP 运动正常的行走相比，中跗关节的运动幅度较小，产生的正功较少。
26 名参与者参加了这项随机交叉研究。参与者在穿着限制 MTP 在中立（BR_NT）或伸展（BR_EX）位置运动的支具的情况下，以 1.3m/s 的速度行走，同时使用运动捕捉来跟踪运动。此外，参与者在支具可自由移动（BR_UN）和不戴支具（CON）的情况下行走。使用压力/剪切感测装置捕获每个足段下的力。在站立阶段，使用逆动力学计算 MTP 和中跗关节的最大关节运动和功。使用一系列 ANOVA 和 Holm 事后检验对所有指标进行检验（α=0.05）。
与 BR_UN 和 CON 相比，支具使 MTP 的最大运动减少了 19%。这与中跗关节运动减少了 9.8%有关。在动力学方面，与 BR_UN 相比，BR_EX 和 BR_NT 中 MTP 关节吸收的功（26%-51%）和中跗关节产生的功（30%-38%）都较少。
在讨论中心性压力转移和节段性足部力变化的背景下，讨论了 MTP 和中跗关节之间的耦合的意义和来源。我们的研究结果表明，旨在调节 MTP 负功的干预措施（如鞋类或辅助设备设计）不应忽视中跗关节。
