The shoulder is a ball in a socket-joint. The socket-part is the glenoid and the ball-part is the upper part of the humerus, the humeral head. Both the socket and the ball are covered with cartlidge that creates the very smooth slippery surface, where the two bones glide onto each other. This cartlidge is specialized tissue and has a friction level better than ice on ice. If this cartlidge wears out the underlying bone gets exposed and the bone on the socket starts scratching on the bone on the humeral head. The bone has very sensitive nerve fibers and that is where the pain originates from. As this bone grinds against each other, it eventually destroys the joint and the whole joint becomes deformed. This is very common in hip and knees where the patient’s carry weight. Hip and knee replacements are well known, as the shoulder does not carry the patient’s weight, arthritic changes in the shoulder does not occur that common. However, if it does happen, the patients are in severe pain and discomfort.
X Ray of a serverely Osteoarthritic shoulder
These patients usually start with pain in the shoulder, that’s spontaneous. They might have had a previous injury to the shoulder that caused the damage to the particular surface. There is usually a grating feeling in the shoulder joint and severe pain. Sometimes the patient complains about the catching of the shoulder due to lose bodies that have formed in the joint that may come in between the two sliding surfaces.
The condition can usually be diagnosed from a normal x-ray of the shoulder joint where one can see that the joint-surface has completely disappeared. The tell-tale sign of an arthritic shoulder is the osteophyte (bone protrusion) that forms on the bottom part of the humeral head. This osteophyte is usually the very first sign of the start of an arthritic issue. On clinical examination one can also feel the grating in the joint and the patient may also be aware of the grating. The movement of the shoulder joint is severely decreased and the diagnosis is really not difficult to make.
One can usually make the diagnosis on the clinical examination and x-ray. CT-scan and MR-scan are usually not indicated for the diagnosis. An ultrasound examination might really be of value to confirm that the rotator-cuff is in-tact, as that might influence the decision-making on the type of replacement the patient needs. Refer to our section on cuff Arthroscopy (the management).
In the early stages the patient can be managed on painkillers and anti-inflammatory tablets. The idea is to delay the replacement surgery as long as possible. To do this at a later stage in life. The life span of prosthesis is about 15 to 18 years and one would tend to do the operation as late as possible during the patient’s life to prevent revision surgery in future.
In other words one would like the prostesis to outlive the patient!!!! On the other hand one can reason that the patient want to live a painfree life now while still relatively young and to face later problems as it comes.
One can also try other motilities of treatment like cortisone injections into the gleno-humeral joint. This suppresses the anti-inflammatory process and might relieve some pain. It is however not a cure to the condition. Usually physiotherapeutic measures do not help, except for pain-relieving motilities.
At some stage one might decide to do a wash-out of the shoulder-joint, using the Arthroscopic technique. This clears the joint of the loose cartlidge that has worn off from the humeral-head and the glenoid and might give some pain relieve.
One might also do some “ice-picking" of the areas where the bone has been exposed. The idea of the “ice-picking” is to create small holes into the bone where blood and stem cells can penetrate the hard bone and hopefully cause some re-growth of the cartlidge. This is also known as “micro-fracture”. The results of this are actually poor and the patient might still have pain post-operatively.
On the long term the patient needs a shoulder replacement, where the socket is replaced with a plastic insert and the humeral-head is replaced with a metal ball. At the operation the sub-scapularus muscle is insized and the humeral-head is dislocated. The humeral-head is then cut to length, the socket is prepared and the small plastic artificial socket is inserted, this is usually attached to the bone with bone-cement. The humeral-head can either be replaced with a stemmed-prosthesis into the shaft of the humerus or simply by resurfacing the humeral head with various techniques.(Refer to our section on shoulder replacement prosthesis.).
These patients do very well, do usually have complete relieve of pain. The range of motion might not always recover as the shoulders might have been very stiff before the operation, but certainly the patient’s pain at night disappears and they are generally much better off.
X ray of a stemmed total shoulder prostesis