ENDOPROSTHESIS OF THE WRIST JOINT Russian patent published in 2023 - IPC A61F2/42 

FIELD: medicine; orthopedics; traumatology and oncology.

SUBSTANCE: invention can be used for prosthetics of post-resection defects of the radius to improve the functional result after the surgical stage. The endoprosthesis of the wrist joint contains a carpal element, which is implanted in the metacarpal bones, and a radial element, which is fixed on the bones of the forearm, connected by a ball joint, where the proximal part of the joint is combined with the radial element. The proximal part of the hinge is releasably connected to the distal part of the hinge. The carpal element contains a jumper, on the opposite sides of which a pin is made in one piece with it, which is implanted in the metacarpal bones, and the distal part of the hinge. The jumper has holes for fixing the carpal element to the bones of the hand. The distal part of the hinge is made in the form of a ball pin, which consists of a shank protruding from the bridge and a spherical head. A spherical insert made of ultra-high molecular weight polyethylene is installed on the spherical head. The insert is made in the form of a hollow spherical segment with grooves extending from the base of the spherical segment. The radial element contains a rod for fixing the prosthesis on the bone of the forearm and a hinge body made in one piece with the rod with a shape close to an elliptical cylinder. The body of the hinge is made with a hemispherical recess, forming a nest for installing a spherical head of the hinge in it, with an insert installed on it. A body cover with a shape close to a hollow elliptical cylinder is installed on the hinge body, one of the ends of which is open, and the other is a closed flat bottom with a cross-shaped through hole for the hinge ball pin. One of the four parts of the cross hole forms a groove on the side surface of the bottom of the lid. The cover is made with rectangular grooves on opposite parts of the side surface, which are intersected by the minor axis of the ellipse, which is the guide curve of the elliptical cylinder, in the form of which the cover is made. Rectangular grooves are aligned with sections of the side surface of the hinge body, on one of which a U-shaped groove is made, which, in turn, is aligned with the groove on the side surface of the cover bottom. The side walls of the four parts of the cross-shaped opening of the bottom of the lid are formed by curved surfaces and smoothly match with each other. The cover is made with holes on the side surface, the axes of which are located in a plane parallel to the ends of the cover, on a straight line passing through the foci of the ellipse formed by the intersection of this plane with the side surface of the cover. One of the holes is threaded. The cover is fixed on the hinge body with a fixing screw installed in the holes on the side surface of the cover, and in a through hole coaxial with them in the hinge body. On two opposite sections of the side surface of the hinge body, through which the hole for the fixing screw passes, guide grooves are made for precise installation of the cover, and on two opposite sections of the side surface of the cover, projections corresponding to them emerging from the bottom of the cover are made.

EFFECT: invention improves the functional qualities of the endoprosthesis, including an increase in the mobility of the endoprosthesis along the sagittal and frontal axes of the wrist joint and the provision of the possibility to perform circular rotation of the hand.

3 cl, 10 dwg, 3 ex