The Use of Adaptive Proximal Scaphoid Implant (APSI): Long Term Follow-up

The adaptative proximal scaphoid implant (APSI) is a pyrocarbon partial scaphoid prosthesis, ovoid and unfixed, which replaces the proximal pole of the scaphoid and allows adaptative mobility in the movements of the first chain and restores the geometry of the carpus, thus preventing the evolution in SNAC (Scaphoid Non-union Advanced Collapse). Pyrocarbon has good compatibility with joint cartilage and bone, a modulus of elasticity similar to bone minimizing stress shielding effects and resorption. The implant is designed with two radii of curvature: in the frontal plane, the smaller radius of curvature corresponds to the scaphoid fossa, and the larger radius of curvature is directed anteroposteriorly to the transverse plane. When it's correctly positioned, the smallest radius of the curvature is visible in the anteroposterior view, whereas it's greater in the lateral view. These two axes of the implant make it adaptable to the kinematics of the wrist.