All about Osteoarthritis - What a patient with OA should know
Osteoarthritis is the most common form of arthritis. Being a non-inflammatory arthritis involving the synovial joints its is characterized by the focal loss of articular cartilage, proliferation of new bone in the surrounding area of the joints and remodeling of the joint contour resulting in failure of the function of the joints, which is to allow normal range of movements with flexibility and smoothening. Even though sufferers may be as young as 30 years, osteoarthritis (OA) is a disease of old age. By 65 years 80% of the population is seen to have radiological evidence of OA although the proportions who are symptomatic are 20-30%. Knee joint and hip joint are the ones commonly involved. Knee joint disease is seen more commonly in women, but the hip joint disease occurs in equal numbers in both sexes.
Osteoarthritis occurs following some kind of an insult to the joints. When the insult is not clear the disease is known as primary OA and when the disease occurs following a recognized insult (mechanical, genetic, metabolic or constitutional) the disease is said to be secondary OA. Risk factors for OA can be classified in to constitutional factors and mechanical factors. Constitutional factors include hereditary susceptibility, female sex for knee OA of the knee joint, obesity and increasing age. Mechanical factors which may lead to OA include trauma to the joint, mal-alignment after dislocation (if not managed and reduced properly), excessive stress on joints (e.g. – hip joint in farmers, knee joint in miners and football players) and other forms of damage to the joint (e.g. – rheumatoid arthritis, infection).
In the initial stages of the disease the joint is remodeled to achieve a joint which is anatomically (structurally) altered but pain free, functioning (compensated OA). However, due to on going damage or failure to repair, progressive tissue damage occurs and the end result is a failure of the function of the joint and pain.
Osteoarthritis can be distressing as it can cause pain and restriction of movements. The pain in OA has some characteristic features.
1. The patient is usually over 45 years and most of the time above 60 years of age
2. The onset of pain is gradual over months to years
3. The severity of pain may be variable with time (there are good and bad days)
4. The pain is related to weight bearing or movement and is relieved by rest
5. There may be a brief period of morning stiffness after a long period of inactivity but does not last more than 15 minutes (unlike rheumatoid arthritis, in which stiffness lasts for at least 30 minutes)
6. The pain is in one or a very few joints
7. The degree of pain perceived and the functional disability may vary depending on the psychological factors and the muscle bulk surrounding the joint (e.g. – patients with wasted quadriceps muscles [thigh muscles] tend to have more functional disability than those with a normal muscle bulk)
If the joint is examined the movements may be found to be restricted and coarse creptius like vibration may be palpable or even audible. There may be bony swellings in the margins of the joint and usually the joint will be found to be deformed without any instability. Pressure over the joint or the surrounding may be painful but there will not be any warmth or redness and if present swelling may also be minimal. The muscles surrounding the joint may be weak in power and may be wasted.
The only investigation required in OA is plain radiography (X-ray) of the involved joint. However, when there is a suspicion about the diagnosis, certain blood tests like full blood count, ESR and CRP may be necessary. Synovial fluid may need to be aspirated if the knee joint is swollen to look for the presence of calcium pyrophosphate dehydrate crystals (CPPD crystals).
Management of OA should start with the recognition of any risk factors present at the time and correction of such factors. Especially postures and activities causing excessive stress on the joint should be avoided. Some examples for knee joint OA are to:
1. Reduce weight
2. Use a walking stick or some walk aid which would take at least part of the body weight
3. Use shock absorbing footwear
4. Alter the footwear to make the length of both legs equal
5. Avoid wearing high heels
6. Avoid postures that would bend the affected joint excessively (e.g. – scotting for knee joint OA)
7. Avoid standing for long periods
8. Avoid climbing steps as much as possible (use an escalator instead)
To strengthen the muscles surrounding the affected joint an exercise schedule can be followed and physiotherapy may also be necessary in advanced cases. Drug therapy is towards relieving pain and the drugs that can be used are paracetamol (acetaminophen), NSAIDs (e.g. – Diclofenac sodium, Ibuprofen) in the form of tablets or local applicants and Capsaicin. When all the above measures fail (evidenced by uncontrolled pain, progressive immobility or functional impairment) the ultimate and the best mode of treatment is surgery. Surgical treatment could be osteotomy (opening in to the joint cavity to relieve pressure inside the joint) for temporary relief or joint replacement. Joint replacement has a very low failure rate being 10% and 15% at 15 years for knee and hip joint replacement respectively.
The criteria for joint replacement are listed below:
1. Severe pain evidenced by
a. Walking limited to 10 minutes
b. Severe pain at rest or severe pain at night
2. Age – older the patient better the outcome as the patients life span is then shorter than the life of the prosthesis (artificial joint)
3. Fitness for surgery and anaesthesia (lung and heart diseases excluded)
4. Exclusion of patients with unacceptable risk of complications (active sepsis, leg ulcers, severe peripheral vascular disease)
Osteoarthritis is a very common disease which is increasing in numbers because of the growth of the ageing population. Prevention of OA is the best but once acquired proper management is necessary to make the quality of life of the affected individuals.