Speed-related increases in plantar tissue stress without affected-side laterality in individuals with unilateral shoulder dislocation.

Introduction: Unilateral shoulder dislocation may be accompanied by altered upper-limb use and trunk-control strategies; however, whether individuals with unilateral shoulder dislocation exhibit affected-side laterality in foot mechanics during walking remains unclear. This study compared the affected-side laterality in plantar external loading and internal foot tissue stresses in individuals with unilateral shoulder dislocation during 5 km/h and 7 km/h treadmill walking conditions, and further examined whether faster walking was associated with changes in this laterality. Methods: Twelve participants completed walking trials at two speeds. Peak forces in the rearfoot and forefoot regions were extracted, and the effects of walking speed, affected-side status, and dominant-foot status were analyzed using foot-level linear mixed-effects models. A simplified peak-force-based finite element analysis was used to estimate relative stress responses in key foot soft tissues during loading-response- and push-off-related loading conditions. Results: The results showed that increased walking speed significantly elevated forefoot peak force ( Conclusion: These findings indicate that, within this cohort, faster walking was associated with higher push-off-related plantar tissue stresses, whereas affected-side laterality relative to the dislocated shoulder was not evident. Because no healthy control group or longitudinal pre-injury comparison was included, the results should be interpreted as within-cohort mechanical responses rather than evidence that shoulder dislocation itself increases plantar tissue stress.