The shoulder region is a complex musculo-skeletal compound of 4 interconnected bones (scapula, humerus, clavicle and sternum) and a series of ligamentary and musculo-tendon structures which provide functionality as well as both active and passive stability during movement. The shoulder (articulatio glenohumeralis), joint between the scapula and the humerus is one of the most complex joints on the human body and as a socket joint it has an expansive range of motion. The spherical head of the humerus goes into the concave joint surface or the glenoid on the scapula. The whole joint is surrounded by the joint capsule and the wide cartilage tissue, labrum glenoidale, increases and stabilizes the joint. Together with the joint capsule and the labrum the ligaments of the glenohumeral joint passively stabilize the shoulder and the rotator cuff and upper arm muscles (m. subscapularis, m. teres minor, m. supraspinatus, m. infraspinatus, m. deltoideus, etc).provide active joint stability.
Shoulder instability is defined as looseness of the glenohumeral joint characterized by dislocation of the joint. The head of the humerus has too much space inside the joint capsule, it is loose and therfore it can partially or completelly go out of its joint socket. The main cause for shoulder instability are loose and overstreched ligaments which do not stabilize the bone leading to subluxations (partial shoulder dislocation) or complete luxations in the joint. The most common injury cause is trauma, ie. falling directly on the shoulder, falls on an outstreched arm or elbow, and blows to the shoulder during which the joint capsule, labrum and ligaments get stretched or damaged andlead joint socket instability. This injury can also be caused by accumulation of microdamages done to the passive and active stabilizers and other shoulder structures during an extended period of time which in the end result in shoulder instability.
Shoulder instability types:
· Degree of instability – subluxation and luxation
· Cause of instability – traumatic and nontraumatic (voluntary, involuntary)
· Dislocation frequency – acute, chronic
· Direction of instability – anterior (TUBS), posterior, multidirectional (AMBRII)
Symptoms include an intense and very sharp pain, inability to move the shoulder or perform any arm movements, disformity of the injured shoulder (convexity or concavity) depending on the direction and degree of dislocation, joint swelling, etc. Habitual, ie. repetitive dislocations are a common occurence if the injury is not treated properly. The shoulder gets so unstable that it dislocates frequently regardless of activity.
Shoulder instability treatment can have a conservative, nonsurgical or surgical course. The nature of treatment depends on the degree and severity of the dislocation and other possible damges in the shoulder. With acute therapy it is important to reduce pain and joint swelling implementing the RICE method (rest, ice, compression, elevation) and later in the functional phase of therapy strengthening of both passive and active shoulder stabilizers should be done to regain joint functionality. In the course of operative treatment the glenohumeral joint gets stabilized with an arthroscopic approach where 1 or more anchors (metal or resorptive) are put inside the joint capsule to hold the humerus tight against the labrum and the joint capsule. It is very important to properly stabilize the shoulder and regain its full functionality in order to prevent possible reccurence of this injury which is very common. Rehabilitation and return to normal activity after this injury last from 4 to 6 months, depending on the degree and gravity of the injury.