A medical device for implantation in a hip joint of a patient, in which said medical device is adapted to be fixed in the patient's pelvic bone (9), and in which said medical device comprises an inner surface (1827 ) and an exterior (1828), the inner surface comprising an equator line (1821), which is the maximum circular circumference of said inner surface, in which a contact portion of said inner surface is spherical and is adapted to face to the center of the hip joint when said medical device is implanted, and in which said medical device is adapted to receive a head of the femur or a head of the prosthetic femur having a spherical part, in which a) said medical device it comprises at least one extension part (1823) that extends beyond said circular equator line and is adapted to grip the head of the femur (5), or a head of the prosthetic femur, in order to retain said head of the femur, or head of the prosthetic femur, in said medical device, b) said medical device is adapted to release the head of the femur or the head of the prosthetic femur with respect to said medical device when a predetermined effort is applied on said medical device, c) characterized in that the extension part is in dorsal position with respect to the proximal-distal axis Y, when implanted, and in which the device The physician comprises a second part that does not extend beyond said circular equator and extends along at least 1/2 of said circular equator line, and extends frontally to said proximal-distal axis Y , such that the range of motion of the hip joint is limited in a non-restrictive manner.Un dispositivo médico para su implantación en una articulación de la cadera de un paciente, en el que dicho dispositivo médico está adaptado para ser fijado en el hueso pélvico (9) del paciente, y en el que dicho dispositivo médico comprende una superficie interior (1827) y una exterior (1828), comprendiendo la superficie interior una línea del ecuador (1821), que es la circunferencia circula
