Physiotherapy Shoulder Rotator Cuff
Posted: Tuesday, February 17, 2009
by Jonathan Blood Smyth
The rotator cuff is a musculotendinous cuff which surrounds the humeral head and through which the shoulder stabilising and movement muscles exert their forces onto the shoulder. The cuff enables us to put our shoulder through a very large range of motion, the greatest range of any joint in the body, for the purpose of putting our hands in functional positions. The shoulder's function is to allow our hands to be put in useful positions within our visual field so we can perform the intricate activities that define being human to a degree.
Many causes of rotator cuff tears have been postulated by there is no agreed single cause, with competing ideas which favour external factors to the tendon and its rival which favours internal degeneration of the tendon itself. The leading shoulder surgeon Neer named impingement syndrome as a condition where the shoulder tendons are repeatedly stressed against the anatomical structures which overlie them. These structures include the acromio-clavicular joint and the front of the acromion, the outside end of the shoulder blade. The supraspinatus tendon can be compressed regularly as the shoulder goes into repetitive flexion and medial rotation,
The lateral part of the scapula, the acromion, has a characteristic anatomical shape and radiological studies have indicated that the hooked shape is connected with cuff degeneration but not necessarily causally linked. Osteophytes, bony outgrowths, develop underneath the acromioclavicular joint and these are compressed against the tendons of the cuff on repeated movement. If a younger worker does a lot of overhead work bleeding and swelling can develop in the tendons and with a series of injuries with time this can develop into tendon scarring and inflammation. In older patients, for example over forty years old, the process can progress to bone spurs and partial or complete cuff tears.
If the arm is taken back into a throwing action, into the cocking part of the process, the edge of the shoulder socket can impinge again and again against the underneath of the supraspinatus tendon. Each time this occurs a small amount of trauma happens in the tendon which can lead to minor tears, particularly occurring in throwing athletes. The lesser tuberosity, the supraspinatus and biceps tendons can impinge against the coracoid process. Overall most cuff tears may be partly explained by these three impingement types.
The idea behind the intrinsic process is that the tendons degenerate with age and this is the basic cause of cuff tears. Younger people rarely show cuff tears and the older people get the incidence of cuff tears rises greatly. Close to the greater tuberosity where the tendon inserts into the bone there is an area underneath the tendon which has a higher risk of getting a tear and has been called the critical zone. This zone was thought to have a poor blood supply and so be more likely to suffer mechanical stresses and less likely to heal well. Further studies have not confirmed this and internal tendon degeneration could be responsible.
Both intrinsic and extrinsic causes may contribute to the degeneration of rotator cuff tendons in real life. The most loaded area of the tendon will begin to fail first, some of the small tendinous fibres rupturing and causing the following consequences. The nearby, intact fibres would suffer increased loads, some fibres become detached from the bone and reduce the power of the cuff, the blood supply becomes compromised by the distorted anatomy and wound healing is compromised which reduces the ability of the area to recover.
Jonathan Blood Smyth is a Superintendent Physiotherapist at an NHS hospital in the South-West of the UK. He specialises in orthopaedic conditions and looking after joint replacements as well as managing chronic pain. Visit the website he edits if you are looking for physiotherapists in London.
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