Expert diagnosis and management of common upper limb conditions
How it Works
The shoulder has the largest range of movement of any joint in the body. The shoulder blade moves on the chest wall. The humerus (arm bone) forms a ball and socket joint with the shoulder blade. The ball, or head of the humerus, is quite large and the socket relatively small and shallow. The head is stabilised in the socket by the rotator cuff. The rotator cuff is made up of the tendons of four muscles which are attached deep on the shoulder blade. The muscle that rests on top of the humeral head and shoulder blade is known as the supraspinatus. It is most at risk of wear against the point of bone on the shoulder blade known as the acromion. This wear will occur when the muscles of the rotator cuff do not control the head of the humerus in the socket well enough with use of the arm away from the body.
There are many types of arthritis. The three most common are osteoarthritis, post traumatic arthritis, and cuff tear arthropathy:
Primary osteoarthritis of the shoulder results from slow degenerative change in the shoulder joint, and is related to the ageing process. Over time cartilage on the joint surface becomes roughened and loses its lubrication properties.
The shoulder blade floats freely in a sling of muscle from the chest wall, apart from the strut of the collarbone which comes off the sternum anteriorly. Minor or major injury can upset the brain’s automatic control of the shoulder blade on the chest wall. A longstanding focus of irritability in the shoulder in particular can prevent the brain from providing the normal support for the postural muscles.
Frozen shoulder is a common condition which can occur in middle age. Its cause is unknown but interestingly it is more common in diabetics. It causes the normally loose bag that holds the ball in the socket to become inflamed and thickened. This results in severe pain as the bag is stretched with movement towards the end of range. The process leads to progressive stiffening of the shoulder
Shoulder Trauma is a common occurrence in young people who participate in an active sporting lifestyle, as well as during everyday life as the result of accidental injury. A broad spectrum of injury patterns can occur. These may be minor, in which case simple pain relief and physiotherapy can be of great benefit, or they can be major and require surgery to get the best result.
Injury or fatigue of the rotator cuff muscles can lead to poor control of the humeral head and wear of the supraspinatus against the acromion. This is appreciated as pain over the outside of the shoulder through an arc when the arm is loaded away from the body. Repetitive use of the arm at and above chest height is a common cause.
The cornerstone of treatment of this condition is to understand the mechanics and avoid loading the arm with the elbow away from the body.