Comprehensive gait analysis is a fundamental step in identifying gait disorders associated with amputation. However, to date, there is limited evidence regarding biomechanical alterations in patients who have undergone toe amputation. One study showed that patients who had undergone first ray amputation displayed poor walking capacity with kinematic alterations in hip extension⁴. The current study expands on this previous knowledge by showing that patients with a history of multiple non-first ray amputations displayed biomechanical alterations characterized by a lack of push-off accompanied by kinematic changes in lower hip extension. These biomechanical alterations would be attributed, at least in part, to the loss of function in the second to fourth toes. Toe amputation reduces leverage, which is required to produce plantar flexor torque during the terminal stance. It should be noted that the patient included in this study had undergone amputation of the third toe in the contralateral limb, suggesting that the poor walking capacity and biomechanical alterations might be a consequence of bilateral toe amputation.

Notably, the biomechanical alterations in the ipsilateral limb were accompanied by an increased vertical first peak GRF in the contralateral limb. The identification of biomechanical alterations in the contralateral limb is valuable, as this may provide insight into musculoskeletal comorbidities after amputation. Increased axial lower limb loading at heel contact may lead to faster progression of existing osteoarthritis¹³. Knee osteoarthritis is a major comorbidity associated with amputation¹⁴. Although no data are available on the prevalence of these comorbidities after partial toe amputation, our findings serve as a foundation for future cohort studies on musculoskeletal comorbidities after partial toe amputation.

Considering that, nearly one-third of the individuals require re-amputation within 1 year following an initial toe amputation¹⁵, an enhanced understanding of the disease trajectory after initial amputation is needed. Elevated plantar pressure is a major risk factor of diabetic ulcers especially at metatarsal¹⁶, a precursor for amputation¹⁷. Our patient displayed reduced step length in the ipsilateral limb, which reduces peak plantar pressure during level walking¹⁸. On the other hand, the COP during the terminal stance in the ipsilateral foot was localized at the first metatarsal, which may cause excessive plantar pressure in this region, the common location for foot ulcers¹⁹. These altered biomechanics in the ipsilateral foot highlight the importance of careful observation following the initial amputation to prevent secondary amputation.