The shoulder joint consists of the head of the humerus and the joint socket. It is surrounded by a capsule, strengthening ligaments and muscles that contribute to the mobility of the joint. A shoulder instability can be caused by a natural disposition (e.g. with a capsule ligament deficiency) or it is the consequence of an injury. With the instability caused by an injury (shoulder luxation) the so-called joint lip (labrum), joint ligaments and capsule can be ruptured or a fracture of the joint socket or of the head of the humerus could have occured additionally. A shoulder instability causes repetitive painful dislocations of the head of the humerus out of its socket, e.g. after heavy falls, sports that involve upside-down postures or even after simple twisting movements. Sometimes the shoulder can only be reposed with help. Sometimes incomplete, painful "subluxations" can occur. The orthopaedic examination can indicate the existence, direction and scale of the shoulder instabililty. On the x-ray picture osseous injuries on the head of the humerus and socket can be diagnosed or ruled out. To recognise any damage on the joint capsule and ligaments a nuclear magnetic resonance tomography of the shoulder has to be done in many cases.
In the case of repeated dislocations with young people who do sports even after the first injury, an operative stabilising is recommended. Only that can avoid a repetitive dislocation of the joint and further secondary consequences.
With the instability due to dispositon without being caused by an injury a specific muscle re-education training is recommended; an operation is usually not necessary. Nowadays the operative methods of treatment are far gentler. Apart from the narcosis the techniques have become far more refined. During an operation the scale of the damage is determined via arthroscopy, by using arthroscopic techniques or via an additional incision into the skin the ligaments are sewn and the joint capsule is stretched, depending on the scale of the injury. The fixing of the ruptured structures around the socket is obtained by the use of 2-3 small "dowel pins" (thread anchors) that are dissimilated by the body within the course of a few months. The generating of missing bone tissue and the use of special thread anchors as well as a refined knotting technique can nowadays determine the expected results more exactly.
