Study and analysis of the mechanical properties and pressure socket for through-knee amputation

Individuals using through-knee (TK) prostheses often face an increased risk of socket failure in various scenarios. This vulnerability is influenced by several factors, including the material of the prosthetic socket and the prevailing stress conditions. The primary objective of this study was to determine the optimal composite materials for TK prostheses, specifically in the context of withstanding fatigue loading in Iraqi rehabilitation centers catering to special-needs patients. A practical investigation was undertaken to evaluate the composite materials utilized in the construction of TK prosthetic sockets. These materials were categorized into three distinct groups: group A comprised three layers of perlon, followed by three layers of carbon, and concluded with three more layers of perlon; group B consisted of three layers of perlon, succeeded by three layers of fiberglass, and concluded with an additional three layers of perlon; and group C featured a total of six layers of perlon. The performance of these groups was assessed through a battery of mechanical tests, encompassing tensile, bending, and fatigue tests conducted in accordance with American Society for Testing and Materials (ASTM) standards. Significantly, group A demonstrated the most favorable mechanical characteristics, primarily attributable to the inclusion of three carbon layers and their intricate matrix configuration. In comparison to groups B and C, the modulus of elasticity for group A increased by 42% and 93%, respectively, and its ultimate stress rose by 21% and an impressive 319%. Consequently, the decision was made to fabricate the TK prosthetic socket using the composite materials from group A. Furthermore, an assessment of socket pressure revealed elevated pressure concentrations within the anterior and lateral regions of the TK prosthetic socket. In order to mitigate discomfort, adjustments were made to the prosthetic legs, resulting in shorter stance phases, extended swing phases, reduced propulsive power, and overall shorter, slower strides. This comprehensive analysis of the TK prosthesis contributes to the refinement of socket fitting techniques and the development of patient-specific customizable sockets, guided by insights derived from gait analysis and interface pressure assessment.