Professor VHS medical center Gangdong-gu, Seoul-t'ukpyolsi, Republic of Korea
Objectives : Lower-limb amputees lack somatosensory input and ankle strategies on the amputated side, making balance control difficult and increasing fall risk. A newly developed Korean ankle prosthesis provides horizontal tilt adjustment to compensate for this limitation. This study aimed to evaluate its effect on static balance by comparing postural stability with a conventional prosthetic ankle.
Design: Ten unilateral transtibial amputees (K-level ≥2) who had used a prosthesis for more than 6 months participated. Static balance was evaluated under eyes-open and eyes-closed conditions using a 3D motion analysis system with eight infrared cameras and one force plate. Center of pressure (CoP) movement, center of mass (CoM) displacement, mean displacement (MDIST), and RMS displacement (RDIST) were assessed during quiet standing. Each participant completed trials using their conventional prosthesis and the newly developed prosthesis, with adequate adaptation time.
Results: With eyes open, the new prosthesis increased CoP ellipse area, MDIST, RDIST, and medio-lateral (Y-axis) movement, but reduced CoM displacement compared with the conventional prosthesis. With eyes closed, the new prosthesis increased Y-axis CoP movement but decreased CoP movement in other directions. CoM displacement increased overall when visual input was removed.
Conclusion: The new prosthesis enhances CoP mobility on the amputated side and reduces CoM sway with visual input. However, under eyes-closed conditions, overall CoM movement increases, indicating partial but limited stabilization.
