Prosthesis for metacarpal-phalangeal and interphalangeal joints in hands or feet

摘要

A metacarpal-phalangeal and/or interphalangeal (1) prosthesis, particularly for joints in the hand or foot, comprising a pair of pins (2, 3) which can be implanted in bone adjacent to a joint to be restored and connected by a flexible joint (4) encapsulated in a protective enclosure formed from the same biocompatible material as the pins. The biocompatible material may be a mixture of plastic resins having high compatibility. The enclosure comprises a pair of half shells (5, 6) integral with the corresponding pins which extend axially on opposite side of a longitudinal plane of symmetry (S) which perpendicularly intersects the axis of rotation (a) of the joint. In a first embodiment, axis (a) is defined by a cylindrical pin (13) inserted in the axial cavity in the half shells and free to rotate with respect to at least one axis with limited flexibility in a plane perpendicular to the axis of rotation (a). In a second embodiment the pin (13) is replaced by a cylindrical (13') or hemispherical (13") extension of one of the pins. Axis (a) may be defined by a helicoidal spring (14, 17) or by axial elastic wires (23, 24) anchored in the pins with transverse end plates (25, 26).