Ground reaction forces during double limb stances while walking in individuals with unilateral transfemoral amputation

The asymmetrical gait of individuals with unilateral transfemoral amputation has been well documented. However, there is not a wealth of investigation into asymmetries during the double limb stance depending on whether the intact or prosthetic limb is leading. The first aim of this study was to compare ground reaction forces during the double limb stance of individuals with unilateral transfemoral amputation depending on whether their intact (initial double limb stance) or prosthetic (terminal double limb stance) limb was leading. The second aim of this study was to compare the asymmetry ratio of ground reaction forces during the double limb stance between individuals with and without unilateral transfemoral amputation. Thirty individuals, fifteen with unilateral transfemoral amputation and fifteen who were able-bodied, were recruited for this study. Each individual walked on an instrumented treadmill for 30 s at eight different speeds, ranging from 2.0 km/h to 5.5 km/h with .5 km/h increments. Ground reaction force parameters, temporal parameters, and asymmetry ratios of all parameters were computed from the data collected. The appropriate statistical analyses of all data based on normality were conducted to investigate the aims of this study. Significant main effects of speed, double limb stance, and their interactions were found for most parameters (p < .01 or p < .05). Individuals with unilateral transfemoral amputation spent a longer duration in terminal double limb stance than initial double limb stance at all tested speeds. They also experienced significantly higher peak vertical ground reaction force during initial double limb stance compared to terminal double limb stance with increasing walking speed. However, during terminal double limb stance, higher anteroposterior ground reaction force at initial contact was found when compared to initial double limb stance. Significant differences between individuals with unilateral transfemoral amputation and able-bodied individuals were found in asymmetry ratios for peak vertical ground reaction force, anteroposterior ground reaction force, anteroposterior shear, and mediolateral shear at all tested speeds. Asymmetrical loading persists in individuals with unilateral transfemoral amputation during double limb stance. Increasing walking speed increased ground reaction force loading asymmetries, which may make individuals with unilateral transfemoral amputation more susceptible to knee osteoarthritis or other musculoskeletal disorders. Further study is necessary to develop ideal gait strategies for the minimization of gait asymmetry in individuals with unilateral transfemoral amputation

THE REBOUND OF THE BODY USING RUNNING-SPECIFIC PROSTHESES IN UNILATERAL TRANSFEMORAL AMPUTEES

Although the elastic bounce of the body is considered a prerequisite for running, the rebound strategy in individuals with lower extremity amputation is not well known. This study aims to investigate the rebound strategy at different running speeds in unilateral transfemoral amputees (uTFAs) wearing running-specific prostheses (RSPs). On an instrumented treadmill, eight uTFAs ran at incremental speeds (30%, 40%, 50%, 60%, 70%, and 80% of the average speed of their 100-m personal records). The rebound strategy of the unaffected and affected limbs is evaluated using the ratio of the natural frequency of the spring-mass system (fsist) to the step frequency (fstep). At all speeds, fsist/fstep in the unaffected limb is considerably greater than that in the affected one. The interlimb differences in fsist/fstep tended to increase with the speed. These results suggest that the rebound strategy is not the same for the unaffected and affected limbs in uTFAs across a range of speeds, and that uTFAs wearing RSPs perform bouncing steps using the alternate asymmetric rebound strategy (fstep \u3c fsist) through different limbs