***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: This study was aim ed at identifying changes in equilibrium and movement control strategies in transtibial amputees ( TTA ) related to both the biomechanical changes and the loss of afferent inflow . The coordinations between equilibrium and movement were studied in traumatical TTA and in controls during transition from bipedal to monopodal stance . TTA failed to perform the task in a high percentage of trials both when the sound and the prosthetic limb were supporting . Significant differences were also found between TTA and controls in the duration of the weight transfer phase , in the length of the initial centre of pressure ( CP ) displacement and in the electromyographic ( EMG ) patterns . Despite adaptive posturomotor control strategies , transition from bipedal to monopodal stance remains a difficult task to perform for TTA , both when the supporting limb is the affected one and when the sound one is . The results of this study are discussed with respect to the rehabilitation programme and the prosthesis design for transtibial amputees BACKGROUND Regaining effective postural control after lower limb amputation requires complex adaptation strategies in both the prosthesis side and the non-amputated side . The objective in this study is to determine the individual contribution of the ankle torques generated by both legs in balance control during dynamic conditions . METHODS Subjects ( 6 transfemoral and 8 transtibial amputees ) stood on a force platform mounted on a motion platform and were instructed to st and quietly . The experiment consisted of 1 static and 3 perturbation trials of 90 s duration each . The perturbation trials consisted of continuous r and omized sinusoidal platform movements of different amplitude in the sagittal plane . Weight distribution during the static and dynamic perturbation trials was calculated by dividing the average vertical force below the prosthesis foot by the sum of forces below both feet . The Dynamic Balance Control represents the ratio between the stabilizing mechanism of the prosthetic leg and the stabilizing mechanism of the non-amputated leg . The stabilizing mechanism is calculated from the corrective ankle torque in response to sway . The relationship between the prosthetic ankle stiffness and the performance during the platform perturbations was calculated . FINDINGS All patients showed a ( non-significant ) weight bearing asymmetry in favor of the non-amputated leg . The Dynamic Balance Control ratio showed that the contribution of both legs to balance control was even more asymmetrical . Moreover , the actual balance contribution of each leg was not tightly coupled to weight bearing in each leg , as was the case in healthy controls . There was a significant positive correlation between the prosthetic ankle stiffness and the Dynamic Balance Control . INTERPRETATION The Dynamic Balance Control provides , in addition to weight distribution , information to what extent the stabilizing mechanism of the corrective ankle torque of both legs contributes to balance control . Knowledge of the stiffness properties may optimize the prescription process of prosthetic foot in lower leg amputee subjects in relation to st and ing stability 
    Output:
    
A majority of the studies revealed that lower extremity amputees have increased postural sway in the st and ing posture .
Asymmetry in body weight , which is mainly distributed in the non-amputated leg , was described .