Patent ID: 8366785

Claim:
A one-piece, basal thumb joint implant comprising a head including a single, smooth, generally hemispherical, media-proximally directed articulating surface, and a generally abrupt, distally directed, planar end thereto, said generally hemispherical articulating surface being continuous as to its sphericity and uninterrupted up to the generally planar end; and a distally directed stem protruding from and monolithic with the head, which stem arises from and makes a junction with the generally planar end of the head, wherein the implant includes the following features: (A) a general angle of junction of the stem with the head, which is about from sixty-five to seventy-five degrees in relation to the generally planar end of the head; (B) a tri-flanged cross-sectional stem profile; (C) an inwardly curved stem; and (D) an eccentric head junction site for the stem; wherein the inward curve of the stem and the eccentric placement of the head on the stem avoid a propensity for dislocation of a replaced joint; such an anatomically oriented arrangement also permits an unobstructed range of normal pain free motion; and the curved stem in conjunction with the flanged cross-sectional stem profile provides for a precise fit with metacarpal medullary canal anatomy, hence preserving bone stock and assuring optimal long term stability, including near if not complete immovability with respect to rotation, of the implant.