A medical device for implantation in a hip joint of a patient, the hip joint having a femur head (5) integrated with a femur neck (6) having a central neck and head axis (CX), which is extends longitudinally along the neck and head of the femur, in the center thereof, wherein said medical device comprises: a) an elongated part (2201) adapted to at least partially replace the neck of the femur, wherein said elongated part is adapted to be at least one of integrated in and connected with a spherical prosthetic part (45) adapted to replace the head of the femur, and in which said spherical prosthetic part in turn is adapted to be placed in a mobile way in a prosthetic replacement for the acetabulum (65) that is fixed to the pelvic bone (9； 1801； 1802； 1803； 1804) and that has at least one extension part (1823) to hold said spherical prosthetic part, in which: i) said elonga part da comprises a restriction part adapted to restrict the range of motion of the spherical part in relation to said prosthetic replacement for the acetabulum, ii) said restriction part of said elongated part is adapted to allow an advantageous range of motion in relation to said prosthetic replacement for the acetabulum, characterized in that b) an important part of said restriction part of said elongated part is adapted to be placed in the dorsal quadrant (1814), when implanted and is in a defined base position, so that the extension is more restricted than flexion.Un dispositivo médico para implantación en una articulación de cadera de un paciente, teniendo la articulación de cadera una cabeza de fémur (5) integrada con un cuello de fémur (6) que tiene un eje central de cuello y cabeza (CX), que se extiende longitudinalmente a lo largo del cuello y la cabeza del fémur, en el centro del mismo, en el que dicho dispositivo médico comprende: a) una parte elongada (2201) adaptada para reemplazar al menos parcialmente el cuello del fémur, en el que dicha parte elongada se adapta para ser al menos una
