Functional effects of a prosthetic torsion adapter in trans-tibial amputees during unplanned spin and step turns

Abstract

Strong coupling between stump and socket will help the user controlling his prosthesis. Shear stress at the stump may increase in stump-socket interface stiffness and may be the reason for residual limb problems. Torsion adapters therefore may be beneficial for comfort and stump condition in individual cases.

Using mechanical testing to assess texturing of prosthetic sockets to improve suspension in the transverse plane and reduce rotation

“…Our normalized torque results for 2.5˚rotation angle under passive suction are comparable to transverse plane moments during walking reported in persons with transtibial amputation [7,14,15,39]. In three persons with unilateral transtibial amputation who wore different suspension mechanisms (gel liner and sleeve; gel liner and pin lock; and pelite liner, socks and cuff), Neumann et al [15] used a load cell mounted into the prosthesis and reported that normalized transverse plane distal socket peak moments ranged from 0.046 ±0.006 Nm/kg to 0.140 ± 0.022 Nm/kg for walking with the prosthetic foot to the inside of a circular path.…”

“…In three persons with unilateral transtibial amputation who wore different suspension mechanisms (gel liner and sleeve; gel liner and pin lock; and pelite liner, socks and cuff), Neumann et al [15] used a load cell mounted into the prosthesis and reported that normalized transverse plane distal socket peak moments ranged from 0.046 ±0.006 Nm/kg to 0.140 ± 0.022 Nm/kg for walking with the prosthetic foot to the inside of a circular path. Segal et al [14,39] and Heitzmann et al [7] compared the effect of a torsion adapter and rigid pylon on transverse plane rotation moments. Segal et al [14,39] studied ten unilateral transtibial prosthesis users who wore liners and sleeves (passive suction) or pin-locking liners.…”

“…The generation of sufficient interface forces to control relative motion without causing other problems continues to be a clinical challenge both in the longitudinal/axial direction as well as the transverse plane. Reducing pistoning [6][7][8][9] and improving suspension in the longitudinal plane using a variety of suspension mechanisms including elevated vacuum, passive suction, and pin-locking liners [10][11][12][13][14] has been investigated, with elevated vacuum suspension generally reducing pistoning more so than other forms of suspension. However, fewer attempts to address transverse plane rotation of the residual limb inside the socket have been described [6][7][8][9].…”

“…Reducing pistoning [6][7][8][9] and improving suspension in the longitudinal plane using a variety of suspension mechanisms including elevated vacuum, passive suction, and pin-locking liners [10][11][12][13][14] has been investigated, with elevated vacuum suspension generally reducing pistoning more so than other forms of suspension. However, fewer attempts to address transverse plane rotation of the residual limb inside the socket have been described [6][7][8][9]. Nevertheless, it remains a clinical problem with prosthesis users reporting unwanted transverse plane rotation within the socket [10][11][12].…”

“…In stance phase, the anatomical ankle and foot act to absorb the forces that occur when the body moves over the foot as it maintains contact with the ground. Prosthetic feet do not provide the same functionality as anatomical feet, resulting in shear stress at the residual limb when walking and especially when turning [7,14,15]. Torsion adapters have been developed to try to minimize the shear stress experienced at the residual limb in persons with transtibial amputation [16,17].…”