Abstract:

BACKGROUND: Studies have been conducted regarding biomechanics of non-individualized prosthesis. But biomechanical data of individualized metacarpophalangeal (MP) joint prosthesis are few.
OBJECTIVE: To explore the superiority of biomechanical characters to detect biomechanics of individualized prosthesis.
METHODS: The experimental specimens were divided into three groups. Individualized prosthesis group (MP joints were replaced by individualized titanium alloy prosthesis), control group (MP joints were replaced by Swanson prosthesis) and normal group (normal human hand). Every group was subjected to vertical loading of 50, 100, 150, 200, 250, 300, and 350 N by CSS-44020 machine. The strain changes of metacarpal and phalanx bone were observed and the loading-strain curves were drawn. The biomechanics of individualized Titanium alloy prosthesis, Swanson prosthesis and normal MP joints were analyzed and compared.
RESULTS AND CONCLUSION: The strain of metacarpal and proximal phalanx bones was increased with increasing loadings. The strain of each test displayed normal distribution. The strain changes of metacarpal bones were greater than proximal phalanx bones at different loading. They all had “platform” period at 300-350 N. No significant strain changes were observed in each group under 50 N loading. The straining changes of control group were significantly different from the other groups when the loading was larger than 100 N. But no differences were observed between individualized prosthesis and normal groups. Results show that individualized titanium alloy prosthesis well matched anatomy of MP joint, and displayed better biomechanics compared with Swanson prosthesis. It provides a novel ideal MP joint for clinical application.