Abstract
<title>Abstract</title> <p>The hand is an important part of the human skeleton, and daily activities are impossible when it malfunctions. One effective surgical solution is arthroplasty, which replaces the damaged joint with a one-piece flexible hinge implant, typically made of silicone, to restore the finger motion. This research focuses on the design of a novel, flexible finger implant for the human Metacarpophalangeal joint. The rectangular box-type hinge in the Nueflex implant is replaced with a spherical hinge in the novel design. The stem portion of the implant is also pre-flexed by 30°, similar to the Neuflex implant, to better reproduce the natural resting position of the finger. In the spherical hinge implant, an elliptical cutout is made at the top of the hinge to allow hyperextension motion, and an additional inverted ‘V’ shape cutout is made at the bottom to facilitate flexion motion. A finite element-based stress analysis is performed on the Nueflex and the novel spherical hinge implants to assess the effectiveness of the new design. The results demonstrate that the novel spherical hinge implant exhibited 23.54% lower von Mises stress during hyperextension and 32.52% lower stress during flexion compared to the Neuflex implant. The spherical hinge implant has 43.49% and 36.49% lower reaction moments in extension and flexion motions than the Nueflex implant. Further, the fatigue life of both implants is assessed, showing that the spherical hinge implants withstand more loading cycles than the Nueflex implant. Hence, the fatigue life is more in the newly designed spherical hinge implant.</p>