The Effect of Neuropathy and Diabetes Type on Multisegment Foot Kinematics: A Cohort Study on 70 Participants with Diabetes

While lower limb biomechanics of people with diabetes are well described, the effects of diabetes type and of peripheral neuropathy on foot joint kinematics have not been addressed in depth. A total of 70 patients with type 1 (n = 25) and type 2 (n = 45) diabetes mellitus, with and without peripheral neuropathy, underwent functional evaluation via gait analysis using an established multisegment foot kinematic model. ANCOVA was performed to assess differences in foot joints’ range of motion (ROM) between groups with diabetes and a control group by accounting for the effects of age, body mass index (BMI) and normalized walking speed. Statistical parametric mapping was used to assess differences in temporal patterns of foot joint motion across normalized gait cycle. Small but significant correlations were found between age, BMI, speed and foot joints' ROM. Regardless of diabetes type and presence of neuropathy, all subgroups with diabetes showed limited ROM at the midtarsal and tarsometatarsal joints. Increased midtarsal joint dorsiflexion and adduction was associated with increased tarsometatarsal joint plantarflexion. After accounting for the effect of covariates, diabetes is associated with reduced ROM and to alterations of the kinematic patterns, especially at the midtarsal and tarsometatarsal joints, irrespective of type and neuropathy.

The Influence of the Windlass Mechanism on Kinematic and Kinetic Foot Joint Coupling

Background: Previous research shows kinematic and kinetic coupling between the metatarsophalangeal (MTP) and midtarsal joints during gait. Studying the effects of MTP position as well as foot structure on this coupling may help determine to what extent foot coupling during dynamic and active movement is due to the windlass mechanism. This study’s purpose was to investigate the kinematic and kinetic foot coupling during controlled passive, active, and dynamic movements. Methods: After arch height and flexibility were measured, participants performed four conditions: Seated Passive MTP Extension, Seated Active MTP Extension, Standing Passive MTP Extension, and Standing Active MTP Extension. Next, participants performed three heel raise conditions that manipulated the starting position of the MTP joint: Neutral, Toe Extension, and Toe Flexion. A multisegment foot model was created in Visual 3D and used to calculate ankle, midtarsal, and MTP joint kinematics and kinetics. Results: Kinematic coupling (ratio of midtarsal to MTP angular displacement) was approximately six times greater in Neutral heel raises compared to Seated Passive MTP Extension, suggesting that the windlass only plays a small kinematic role in dynamic tasks. As the starting position of the MTP joint became increasingly extended during heel raises, the amount of negative work at the MTP joint and positive work at the midtarsal joint increased proportionally, while distal-to-hindfoot work remained unchanged. Correlations suggest that there is not a strong relationship between static arch height/flexibility and kinematic foot coupling. Conclusions: Our results show that there is kinematic and kinetic coupling within the distal foot, but this coupling is attributed only in small measure to the windlass mechanism. Additional sources of coupling include foot muscles and elastic energy storage and return within ligaments and tendons. Furthermore, our results suggest that the plantar aponeurosis does not function as a rigid cable but likely has extensibility that affects the effectiveness of the windlass mechanism. Arch structure did not affect foot coupling, suggesting that static arch height or arch flexibility alone may not be adequate predictors of dynamic foot function.

“Double-bundle” tibialis anterior tendon transfer for prevention of pes equinus after Chopart amputation

Objective: Assess patient performance and quality of the stump after amputation at the Chopart (midtarsal) joint, with double-bundle transfer of the tibialis anterior muscle tendon to the talar neck. Methods: This study evaluated the medical records of 5 patients who underwent Chopart amputation with double-bundle transfer of the tibialis anterior tendon to the talar neck, assessing pre and postoperative performance and gait. Results: The patients were operated on between January 2008 and December 2018, and the data obtained from the survey allow us to conclude that, after the proposed procedure, all patients reported an improvement in walking, besides noting a significant reduction in the degree of stump equinus. Conclusion: The surgical technique described in this article produced a significant improvement in patient performance as assessed by the AOFAS hindfoot score, and prevented the formation of ulcers in the anterior region of the stump. Level of Evidence IV; Therapeutic Study; Case Series.

Ankle and midtarsal joint quasi-stiffness during walking with added mass

Examination of how the ankle and midtarsal joints modulate stiffness in response to increased force demand will aid understanding of overall limb function and inform the development of bio-inspired assistive and robotic devices. The purpose of this study is to identify how ankle and midtarsal joint quasi-stiffness are affected by added body mass during over-ground walking. Healthy participants walked barefoot over-ground at 1.25 m/s wearing a weighted vest with 0%, 15% and 30% additional body mass. The effect of added mass was investigated on ankle and midtarsal joint range of motion (ROM), peak moment and quasi-stiffness. Joint quasi-stiffness was broken into two phases, dorsiflexion (DF) and plantarflexion (PF), representing approximately linear regions of their moment-angle curve. Added mass significantly increased ankle joint quasi-stiffness in DF (p < 0.001) and PF (p < 0.001), as well as midtarsal joint quasi-stiffness in DF (p < 0.006) and PF (p < 0.001). Notably, the midtarsal joint quasi-stiffness during DF was ~2.5 times higher than that of the ankle joint. The increase in midtarsal quasi-stiffness when walking with added mass could not be explained by the windlass mechanism, as the ROM of the metatarsophalangeal joints was not correlated with midtarsal joint quasi-stiffness (r = −0.142, p = 0.540). The likely source for the quasi-stiffness modulation may be from active foot muscles, however, future research is needed to confirm which anatomical structures (passive or active) contribute to the overall joint quasi-stiffness across locomotor tasks.