The shoulder is a highly mobile and relatively unstable joint with the largest range of motion of all the body's joints. The shoulder is designed to allow us to put our hands in front of our vision so we can watch as we perform complex manual manoeuvres, a defining feature of primates and humans. The shoulder has a group of muscles which stabilise and move the joint, a group known as the rotator cuff, which forms a tendinous cuff around the head of the humerus so that it can exert the necessary forces.
The rotator cuff muscles stabilise and move the shoulder joint, originating from the shoulder blade and narrowing down towards the greater tuberosity where the tendons become flattened into a fibrous sheet, unlike many other bodily tendons which are cylindrical. The ability to heal and the vasculature of the cuff may be limited at times, with physical stresses and time causing tears which may or may not be painful. The diagnosis of rotator cuff tears is a large part of the work of a shoulder surgeon and rotator cuff repairs are a significant operative load. The post-operative protocols are followed by physiotherapists to ensure a good outcome.
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.
A third impingement type can occur in throwing as the arm is cocked back for the throw and the edge of the glenoid socket can be forced repeatedly against the lower surface of the supraspinatus tendon. Minor trauma is produced each time this occurs, gradually developing into small tears particularly in athletes who throw a lot. The biceps and supraspinatus tendons and the lesser tuberosity impinge against the coracoid process. Most rotator cuff tears are probably contributed to by these three impingement process.
The intrinsic view holds that the external factors may be contributory but that the fundamental underlying process is age-related degeneration inside the tendons themselves. This helps explain why young people rarely suffer cuff tears and that tears increase strongly with age, for example after fifty years old. Under the supraspinatus tendon near to its insertion onto the greater tuberosity is an area which has been called the critical zone and postulated to have a poor vascular supply. This could increase the risk of injury and poor healing in this area but further studies have not confirmed this idea so degenerative changes in the tendons may still be important.
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. - 14130
The rotator cuff muscles stabilise and move the shoulder joint, originating from the shoulder blade and narrowing down towards the greater tuberosity where the tendons become flattened into a fibrous sheet, unlike many other bodily tendons which are cylindrical. The ability to heal and the vasculature of the cuff may be limited at times, with physical stresses and time causing tears which may or may not be painful. The diagnosis of rotator cuff tears is a large part of the work of a shoulder surgeon and rotator cuff repairs are a significant operative load. The post-operative protocols are followed by physiotherapists to ensure a good outcome.
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.
A third impingement type can occur in throwing as the arm is cocked back for the throw and the edge of the glenoid socket can be forced repeatedly against the lower surface of the supraspinatus tendon. Minor trauma is produced each time this occurs, gradually developing into small tears particularly in athletes who throw a lot. The biceps and supraspinatus tendons and the lesser tuberosity impinge against the coracoid process. Most rotator cuff tears are probably contributed to by these three impingement process.
The intrinsic view holds that the external factors may be contributory but that the fundamental underlying process is age-related degeneration inside the tendons themselves. This helps explain why young people rarely suffer cuff tears and that tears increase strongly with age, for example after fifty years old. Under the supraspinatus tendon near to its insertion onto the greater tuberosity is an area which has been called the critical zone and postulated to have a poor vascular supply. This could increase the risk of injury and poor healing in this area but further studies have not confirmed this idea so degenerative changes in the tendons may still be important.
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. - 14130
About the Author:
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 Leeds.
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