Biomechanical Analysis of Nigerian Wooden Crutches: Ergonomic Redesign and Material Substitution Using Bamboo Polymer Composites

Abstract

Background: Prolonged use of traditional wooden crutches in Nigeria has been associated with significant secondary complications, including pressure ulcer formation at the axillary region and axillary nerve injury. The predominance of wooden crutches fabricated fromGmelina arboreain Nigerian healthcare facilities presents ergonomic and biomechanical limitations that compromise patient safety and comfort. This study presents a comprehensive biomechanical analysis and ergonomic redesign of crutches using bamboo-polymer composite materials, with specific adaptation to the Nigerian context. A total of 12 adult subjects (6 male, 6 female) from Bayelsa State, Nigeria, underwent 3D anthropometric measurements to establish ergonomic design parameters. Finite element analysis (FEA) was conducted using ANSYS Workbench to evaluate load distribution patterns under simulated walking conditions. Bamboo (Bambusa vulgaris)-epoxy composite crutches were fabricated using the hand lay-up technique with fiber volume fractions of 55%, 60%, and 65%. Three-point bending tests (ASTM D790), compressive strength tests, and fatigue testing were performed to characterize mechanical properties. Process optimization was conducted using ASPEN Plus software to determine optimal fabrication parameters. Ergonomic comfort was evaluated through a validated questionnaire-based assessment protocol. The FEA analysis revealed that traditional wooden crutches produced stress concentrations of 18.4 MPa at the axillary contact region, exceeding the threshold for soft tissue damage. The optimized bamboo-epoxy composite (55:45 fiber-to-resin ratio) demonstrated a flexural strength of 75.3 MPa, representing a 114% improvement over traditional wood (35.2 MPa). Compressive strength increased by 142% (68.7 MPa vs. 28.4 MPa), and fatigue endurance limit improved by 73% (38 MPa vs. 22 MPa). ASPEN Plus optimization identified 25 degrees Celsius curing temperature and 48-hour cure duration as optimal parameters. The redesigned crutch with padded axillary support and ergonomic hand grip achieved a mean comfort score of 8.4 out of 10 compared to 4.3 for traditional designs, with pressure ulcer risk scores reducing by 56% over 120-minute usage duration. The bamboo-polymer composite crutch represents a sustainable, biomechanically superior alternative to traditional wooden crutches in Nigeria. The ergonomic redesign, informed by local anthropometric data and validated through FEA and mechanical testing, significantly reduces the risk of pressure ulcer formation and nerve compression injury while providing superior mechanical performance. The utilization of locally abundant Bambusa vulgaris offers economic and environmental advantages for scalable production in the Niger Delta region.