Knee replacement

Click on each of the following to find out more.

+ Types of knee replacements

There are more than 150 knee replacement designs on the market, but generally there are only three types of knee replacement:

• single compartment knee replacement – involves replacement of either the medial or lateral tibiofemoral joint
• 'unconstrained' two compartment knee replacement – this is the most common form of total knee replacement and involves creating a new joint that mimics the anatomy of a normal joint
• 'constrained' two compartment knee replacement – this doesn't mimic normal anatomy, it makes the joint act like a fixed hinge.

+ Why do people have knee replacements?

People have knee replacements to relieve pain, restore function and improve quality of life.

The most common reason people have a knee replacement is osteoarthritis. Other reasons include rheumatoid arthritis, osteonecrosis, gout, bone dysplasia/cancer and obesity.

+ What does it involve?

The surgery involves replacing the damaged parts of the knee joint with synthetic parts (called prostheses or implants). These may be cemented into place. The surgery may be done under general anaesthetic or epidural.

The knee joint is usually approached from the inner side of the knee. Sometimes the ligaments will be tight/contracted and will need to be released.

+ What could I expect after a knee replacement?

You can expect to be moving your new knee soon after surgery. To get you up and around comfortably, you will be given good pain control and physiotherapy.

Most people are able to go home 1–4 days after surgery.

You will probably be able to resume normal activity 3–6 weeks after surgery. Most people can go back to work after 6-8 weeks, depending on the type of work done.

+ What would stop me having a knee replacement?

There are a few contraindications to knee replacement, including:

• active infection (either in the knee or elsewhere)
• poor knee extensor function
• significant arterial disease
• past history of osteomyelitis.