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

Abstract

Creating a secure and comfortable linkage between the residual limb and prosthetic socket in persons with lower limb amputation is a critical factor for successful rehabilitation, including ambulation and other activities of daily living. Unwanted rotation within the socket can be a clinical problem for prosthesis users. One way of addressing issues experienced with transverse plane control of the socket may be through increased friction interface forces. It has been proposed that friction at the residual limb/socket interface may be increased by adding texture to interface components. Three-dimensional (3D) printing may be used to fabricate sockets with texture patterns added to the inner socket surface. Hence, the aim of this study was to investigate the effects of socket texturing on transverse plane rotation of the socket on a mock residual limb under two suspension conditions: passive suction and active vacuum. To conduct this study, we developed a mechanical testing protocol as no standardized tests currently exist to assess prosthetic sockets. Sockets with 14 different texture patterns were fabricated using the Squirt-Shape™ 3D printer. Textured sockets were compared to an Original Squirt-Shape (OSS) socket and a smooth thermoformed socket. Sockets were fitted with a mock residual limb and bi-axially loaded to 350 N compression with simultaneous rotation (2.5˚, 5˚and 7.5˚) using a custom rotation assembly attached to a uniaxial hydraulic material testing system. There was a statistically significant three-way interaction between suspension, angle and texture (p < 0.0005). Torques between textured and reference sockets, for all rotation angles and both suspension conditions, were significantly different (p < 0.0005). Using newly developed testing protocols, it was demonstrated that some texture patterns significantly increased torque (i.e., resistance against unwanted rotation) in the transverse plane compared to both OSS and smooth sockets, especially for passive suction. Rotation testing of sockets may provide insight into socket design to improve suspension in the transverse plane.

Functionality and Comfort Design of Lower-Limb Prosthetics: A Review

“…Various suspension methods, including suction, vacuum-assisted, and strap-based systems, are utilized to achieve secure and comfortable suspension. The socket design should accommodate the necessary suspension mechanism while ensuring stability and minimizing unwanted movements (Quinlan et al, 2020a(Quinlan et al, , 2020b.…”

“…This adaptability extends the lifespan of the socket and ensures an optimal fit and function over time. The interface between the residual limb and the socket, along with the suspension system, significantly influences socket performance (Quinlan et al, 2020a). Soft interfaces, such as silicone liners, help improve comfort, cushioning, and moisture management.…”

Surface profile of laminated transfemoral socket fabricated with different types of reinforcement materials

“…Surface roughness helps the patient by controlling the unnecessary rotation of a socket. 11 In 2020, Quinlan et al 12 using recently created testing procedures, revealed that various textured patterns greatly enhanced torque in the transverse plane more than smooth sockets, particularly for passive suction.…”