| abstract |
A joint prosthesis for replacement of the metacarpal-phalangeal (MP) joint (19) of a human finger which includes a metacarpal element (13) with a stem (15) for reception into the medullary cavity of the metacarpal bone (11) and a generally ball-shaped articular head (17) and a phalangeal element (14) with a stem (16) for reception into the medullary cavity of the proximal phalangeal bone (12) and a generally socket-shaped head (18) which conforms to the ball-shaped head (17). The metacarpal element (13)'s articular head (17) has reliefs (51,52) located on each of its two lateral sides so as to provide a generally free path for the collateral ligaments (43,44). The phalangeal element (14)'s articular head (18) has a dorsal protrusion (71) that resists subluxation-dislocation of the phalangeal bone (12) and grooves (31,32) in its concave surface (22) which allow biological fluids access to the inner regions of the articulation contact surfaces (21,22). The proximal face of the head (18) may be tangent to a plane (P), or the face of the head (118) may be tangent to a cylinder of circular cross section to provide greater capture and joint stability. |