SEMICONSTRAINED TOTAL ELBOW PROSTHESIS MADE OF SHAPE-MEMORY ALLOYS, WITH COUPLING SYSTEM BASED ON SHAPE-MEMORY EFFECT

摘要

The invention relates to a semiconstrained total elbow prosthesis made of TiNi biocompatible shape-memory alloys meant to replace the human elbow joint affected as a consequence of accidents or bone or joint diseases. The prosthesis, as claimed by the invention, has two components: a. an ulnar component (1) which is fixed in the medullary canal of the ulna and consists of a fixation rod of truncated pyramid shape, with a length of 50...200 mm, with a square-shaped end cross-section having a side of 3...10 mm and an angle of flaring of 1...5° towards the cylindrical end in which the articulation recess is cut out, the fixation rod having rounded edges at one end and the other end being transverse cylindrical with a diameter of 7...20 mm and a length of 10...30 mm, b. a humeral component (2) which is first fixed on the humeral bone canal and which comprises a fixation rod with a length of 50...200 mm, with a square-shaped end cross-section having a side of 3...10 mm and an angle of flaring of 1...5° towards the attachment extension, with a flange for external support onto the bone with a length of 10...20 mm, a width of 5...10 mm and a thickness of 2...5 mm and an attachment extension with a length of 5...10 mm, a thickness of 3...10 mm, and the circular bending angle of 175...260°, all the edges being rounded, with a radius of curvature ranging between 0.1...2 mm, the winding of the attachment extension of the humeral component (2) on the recess in the transverse end of the ulnar component (1) being carried out by activating the shape-memory properties of the alloy, meaning that the open position is activated at a low temperature of 1...3°, and the closed position is activated at a temperature slightly lower than the temperature of the human body, namely between 30...33°C.