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The function of the human arm is to allow placement of the hand in useful positions so the hands can perform activities where the eyes can see them. Because of the huge range of positions required the shoulder is very flexible with a large motion range, but this is at the expense of some reduced strength and greatly reduced stability. A “soft tissue joint” is often a description of the shoulder, indicating it is the tendons, muscles and ligaments which are important to the joint’s function. Shoulder treatment and rehabilitation is a core physiotherapy skill.

The shoulder joint is constructed from the socket of the scapula and the humeral head, the ball at the top of the upper arm bone. The head of the upper arm is a large ball and important tendons insert onto it to move and stabilise the shoulder, but the shoulder socket, the glenoid, is small in comparison and very shallow. A cartilage rim, the labrum of the glenoid, deepens the socket and adds to stability. The acromio-clavicular joint lies above the shoulder joint proper and provides dynamic stability during arm movements, being made up from part of the scapula and the outer end of the clavicle.

The major stability and flexibility joints of the upper limb shoulder girdle are the scapulothoracic and glenohumeral joints and these joints are held steady and moved by large and powerful muscles. The pectoralis major and latissimus dorsi muscles stabilise and perform strong movements, the serratus anterior stabilises the scapula on the thorax, the rotator cuff stabilises the humeral head on the socket and the deltoid and other muscles perform movements. The shoulder blade and thorax need to be kept in a stable relationship for the glenohumeral joint to perform precise and controlled movements.

The shoulder muscle tendons become flatter and thinner as they approach and then insert themselves onto the head of the humerus. By this way the rotator cuff, a group of four muscles including the supraspinatus, infraspinatus, teres minor and subscapularis, is able to exert its forces on the humeral head. The tendons coalesce as they surround and insert onto the ball of the humerus, forming a cuff around the ball, centering the ball on the socket to counter the tendency to slide upwards under muscle activity. Keeping the ball centred on the socket means the larger and more powerful muscles can perform functional shoulder and arm movements.

With age, small degenerative tears occur in the tendons of the cuff, in some cases painful and in others not, causing loss of movement and strength. As tears progress they can become massive, cutting off the cuff muscle power from the humeral head and severely reducing function. Rotator cuff strengthening work is performed by physiotherapists and if the tears are severe they concentrate on anterior deltoid strength to improve functional ability in the absence of cuff power. Shoulder surgeons can repair many rotator cuff tears and physiotherapists rehabilitate patients following the shoulder protocols.

Osteoarthritis (OA) does not commonly affect the shoulder but there is a group of patients who develop severe arthritic problems in the shoulders, whom physiotherapy can help by maintaining joint ranges and muscle power. Once conservative treatments are exhausted then total shoulder replacement (TSR) is possible, either replacing the ball and socket with new components or reversing the combination. Physiotherapy post-operative management is very important as the shoulder is a “soft tissue joint” in the sense that the strength and balance of the shoulder muscles and other tissues is vital for good outcome.

Physiotherapists treat many other types of shoulder problems such as impingement, tendinitis, hypermobility, abnormal muscle patterning, fractures and dislocations. Impingement is treated by strengthening the rotator cuff or by subacromial injection or acromioplasty operation, where the end of the acromion can be excised. Tendinitis is treated by direct treatment of the tendon and graded strengthening and hypermobility by stability work and accepting the limitations dictated by the condition. Abnormal muscle patterning is managed by teaching normal patterns functionally and fractures and dislocations by the protocols laid down by the surgeons and trauma physiotherapists.

Tags: Health & Fitness //