Study of Medial-Lateral Center of Pressure Displacement in Unilateral Transfemoral Amputees

Study Summary

The purpose of this study is to examine the path and velocity of the center of mass (CoM) and center of pressure (CoP) during double support of persons walking with a unilateral above-the-knee prosthesis and determine the effects of prosthetic foot stiffness and effective length on CoM and CoP.Persons with a lower limb amputation walk with compensatory movements that affect the smooth trajectory of the center of mass (CoM) during weight transfer. The lack of control in the foot/ankle complex reduces fine motor movements, influencing the progression of the CoM and transfer of ground reaction forces represented by the center of pressure (CoP). Without control of the ankle joint, prosthetic users "fall" off of their trailing prosthetic limb during weight transfer, resulting in much more abrupt CoM and CoP transfers from trailing to leading limb. These abrupt movements during transfer not only increase stress on the sound limb, but also decrease the subject's energy efficiency during ambulation. The current study will further examine the CoP path and velocity in relation to the CoM path and velocity during double support of men with a transfemoral prosthesis, as well as explore how prosthetic foot ankle stiffness and effective length affects the CoP path and velocity.

Primary Outcome

The Center of Pressure velocity in the X and Y direction \[cm/sec\] will be collected using a motion capture system and forceplates during a single session. This data will be collected during a single 2.5 hour data collection session. The time frame is specifically the Double Support phase of the gait cycle.

Interventions

• OTHER Level overground ambulation