Osteoarthritis

Definition

Mechanical degenerative disease of the joints

Epidemiology

Very common. 8 million people in the UK are affected and it is thought that up to 80% of the US population will develop radiographic evidence of the disease (although not all will develop symptoms).

Pathophysiology

Osteoarthritis, though common, does not occur in everybody. It is not caused by aging, simply that older people are more likely to have it because of the degenerative nature. Essentially, water content of cartilage is reduced making the cartilage less resilient. This means all the damage (described under investigations) is due to cartilage being less effective.

Risk Factors

Trauma can cause it and there is thought to be a genetic component. Obesity can also be a factor. Otherwise, there aren't any specific risk factors.

Clinical Features

Heberden's nodes. Cool as a cucumber in a fridge in the Arctic in another fridge.

Basically, pain (described as a sharp ache made worse by movement) and loss of mobility. Stiffness, crepitus and effusion (particularly in the knee) can also result. It affects large weight-bearing joints such as the hips and knees but can affect any joint in the body. It also presents with Heberden's nodes in the hands (see right).

Investigations

Joint X-ray

The following features are characteristic of an osteoarthritic joint:

• loss of cartilage
• subchondral sclerosis - increased bone turnover directly below the cartilage
• subchondral cyst - microfractures occur and are then filled with fluid forming cysts.
• narrowing of joint space
• osteophytes - bony spurs

Management

Non-medical

• Lifestyle - lose weight, low-impact exercise (walking or swimming),
• Physical therapy - occupational therapist and physios can help the patient deal with day-to-day functioning
• Education

Medical

There are lots of drugs that can be used

• Paracetamol and topical NSAIDs- These are used first-line.
• Oral NSAIDs - if the above fail to provide sufficient pain relief. Should be prescribed with a PPI in order to avoid gastric ulcers. Be careful if they're already on aspirin.
• Opiates - if paracetamol and NSAIDs do not provide sufficient pain control.
• Injections - corticosteroid injections should be used in conjunction with other pain control. Relief can last weeks to months.

Surgical

Joint replacement is the last-line treatment where all other OA treatments have failed. How long a joint lasts depends on which joint is replaced. The most common are hip replacements.