FIELD: medicine.SUBSTANCE: invention refers to medicine, namely to surgical orthopaedics, and can be applied to total hip joint replacement. Hip joint endoprosthesis consists of acetabular component, insert, spherical head, neck, and endoprosthesis stem. Neck base has shape of cylinder with ledge at bottom and inner thread along base, and is located in cylindrical channel located in upper part of endoprosthesis stem, and located along axis of stem. In channel, parallel to it, along its whole length, there are slots at outer side connected to each other into one slot in lower part of channel. Neck base ledge is in one of slots. Middle part of stem has first cavity located along axis of stem. Lower part of stem has second cavity of rectangular parallelepiped form, located along axis of stem. Second cavity is connected to first chamber and cylindrical channel in top part of stem by top and bottom cylindrical through holes arranged along axis of stem. In lower through hole and in second cavity there is rod of rectangular cross-section. Magnet in parallelepiped form with rectangular opening at center is located on rod in second cavity and has clamping spring at its bottom located on rod. When no effect upon magnet is exerted by external magnetic field, it stays in locking slot of rectangular parallelepiped form, located perpendicular to axis of stem in upper part of second cavity, and in upper through hole there is pin, screwed into thread of neck base. In first cavity there is reducer connected to upper end of rod and to lower end of pin.EFFECT: increased range of joint motion, possibility to change extremity length and recover length with maximum accuracy after operation, possibility to change antetorsion of endoprosthesis neck and, accordingly, prevention of joint dislocations after operation, creating conditions for optimum tension of pelvic and trochanter muscles, optimisation of biomechanical parameters, and improved treatment results.1 cl, 7 dwgИзобретение относит
