Osteoarthritis occurs when the protective surface (cartilage) that allows the joint to move smoothly is damaged. Over time this cartilage dries up and starts to fragment so the surface becomes very worn and rough. This leads to pain and stiffness in the joint and often will cause “creaking” in the joint.
There are 2 joints at the shoulder that may become arthritic. The acromioclavicular joint (AC Joint) is a small joint at the top of the shoulder between the collar bone (clavicle) and the shoulder blade (scapula). The main joint is the ball and socket joint (glenohumeral joint) which is formed between the ball on the upper end of the arm bone (humerus) and the socket (glenoid) on the shoulder blade (scapula).
Arthritis of the acromioclavicular joint (ACJ) is fairly common and is frequently seen on shoulder x-rays although doesn’t necessarily cause symptoms. It should not be confused with arthritis of the main ball and socket joint (glenohumeral joint). When symptomatic, ACJ arthritis can be treated by a steroid injection or removing the end of the collarbone so the arthritic surfaces of the joint don't rub together and cause pain. The end of the collarbone can be removed as part of a keyhole (arthroscopic) procedure performed as a daycase.
Glenohumeral Arthritis (ball and socket)
Osteoarthritis of the shoulder is less common compared to many other joints, including the hips, knees, feet and hands. It can still cause significant pain and since the main purpose of the shoulder joint is to position the hand for activity it leads to major loss of function of the arm.
Osteoarthritis is the commonest cause of shoulder arthritis and is often explained as 'wear and tear' arthritis. The precise cause is not fully understood but several factors have been identified in predisposing its onset. These include a family history, previous trauma especially fractures or dislocations, and overuse of the shoulder, eg. long term heavy manual work, weight lifting and racquet sports as well as genetic links.
There are two other causes of arthritis of the shoulder: inflammatory arthritis (eg. rheumatoid arthritis) and rotator cuff arthropathy.
Rheumatoid arthritis is a widespread disease found throughout the body in which the patient’s own immune system mistakenly attacks the joints causing widespread inflammation and damage.
Rotator cuff arthropathy is the term that is given to arthritis that occurs after long standing large tears of the deep tendons (rotator cuff) of the shoulder. Although it is far less common than the other forms of arthritis it is often far more disabling as the mechanics of the joint are significantly altered.
The symptoms that patients experience with arthritis of the shoulder (ball and socket) include:
Pain - which is worse on use of the arm and often associated with painful “catching” and ‘creaking’.
Stiffness - especially lifting the arm above shoulder height or rotating the arm, especially going behind the back.
Night pain - sleep is frequently disturbed and patients have difficulty lying on the affected side
Loss of function - limited ability to perform normal activities, especially activities at head height, eg. reaching items out of high cupboards, doing hair etc Clicking or grinding in the shoulder on movement
These symptoms generally deteriorate with time.
Treatment of shoulder arthritis
Osteoarthritis of the shoulder is initially treated by physiotherapy including exercises to maintain movement and strength. This is often combined with painkillers including paracetamol, codeine and anti-inflammatories such as ibuprofen/naproxen. Your GP can advise you regarding these medications. Supplements such as Glucosamine tablets may potentially help in early stage arthritis.
Patients who suffer from Rheumatoid arthritis need advice from a specialist Rheumatologist who can provide expert management regarding medications that can suppress the effects and progression of the Rheumatoid disease.
A steroid injection into the shoulder joint (glenohumeral joint) may give temporary benefit and relief of pain. Newer artificial lubricating fluid injections (hyaluronic acid) may also be used in the early stages. They have been shown to give longer benefit than steroids with fewer side effects but are more costly (not always covered by insurance companies) and will most likely be temporary.
If the measures described so far fail to control the symptoms then surgery may be considered.
A keyhole (arthroscopic) debridement of the joint may be performed which aims to smooth off the rough surfaces and remove debris. The stiff capsule which also occurs in arthritis can be released to potentially improve some the range of movement. This usually only gives limited temporary benefit so is only really indicated in patients in whom we are trying to avoid a shoulder replacement operation.
When symptoms become severe with constant pain, night pain and loss of function then a shoulder joint replacement is indicated. The main surgical options are to perform either a total joint replacement (both the surface of the ball and socket are replaced) or a hemiarthroplasty joint replacement (only the surface of the ball, humeral head, is replaced but the socket surface is not replaced).