Regional Plantar Pressure in the Transmetatarsal Amputation Limb Under Different Contralateral Limb Conditions: An Exploratory Case-Comparison

Background: Transmetatarsal amputation (TMA) alters foot biomechanics and is associated with abnormal plantar loading that may contribute to plantar tissue breakdown. Although plantar pressure abnormalities following TMA have been reported, the potential role of contralateral limb status in regional plantar loading patterns remains incompletely understood. This exploratory case-comparison study examined plantar loading under two different contralateral limb conditions. Methods: This exploratory case-comparison evaluated in-shoe plantar pressure in two individuals with unilateral TMA: one with an intact contralateral limb and one with a contralateral transtibial prosthesis. Plantar pressure data were collected using a Pedar-X system during overground walking at a self-selected speed. Regionally resolved outcome measures, including peak plantar pressure (PPP), pressure–time integral (PTI), and maximum force (MF), were calculated for the TMA limb. Interlimb asymmetry was assessed in the unilateral TMA participant using normalized asymmetry indices (AIs). Results: The participant with a contralateral transtibial prosthesis exhibited substantially higher PPP and MF across all TMA regions (increases of approximately 40–99%) compared with the participant with an intact contralateral limb. In contrast, PTI values were lower under the prosthetic condition. Within-subject analysis revealed pronounced interlimb asymmetry, with increased midfoot loading in the TMA limb (PPP AI: +38–44%; MF AI: >100%) and greater rearfoot loading in the intact limb (PPP AI: −25% to −35%). Conclusions: In this exploratory case-comparison, the participant with a contralateral transtibial prosthesis exhibited higher regional peak plantar pressures and maximum forces, together with lower pressure–time integrals, than the participant with an intact contralateral limb. Regional asymmetry was also observed in the unilateral TMA participant. These descriptive findings suggest that contralateral limb condition may be associated with differences in plantar loading patterns; however, the observations should be interpreted cautiously because of the exploratory nature of this two-participant case-comparison. Future studies involving larger cohorts are needed to determine whether these observations are generalizable.