Knee Replacement - Causes

Authored by Dr Jacqueline Payne, 04 Jul 2017

Patient is a certified member of
The Information Standard

Reviewed by:
Dr Helen Huins, 04 Jul 2017

What is the knee joint?

There are four bones around the area of the knee joint: the thigh bone (femur), the main shin bone (tibia), the outer shin bone (fibula) and the kneecap (patella). The main movements of the knee joint are between the femur, the tibia and the patella.

Each knee joint also contains an inner and outer meniscus (a medial and lateral meniscus). The menisci (plural of meniscus) are thick rubbery pads of cartilage tissue. The menisci act like shock absorbers to absorb the impact of the upper leg on the lower leg. They also help to make the knee movements smooth and help to make the knee stable.

Cross-section of a normal knee joint

Your knee doesn't just bend and straighten like a hinge: just before you fully straighten your knee, there is a little twist of your thigh bone (femur) onto your shin bone (tibia).

What are the main causes of needing a knee replacement?

The main reason for needing to have a knee replacement is arthritis in your knee:

Osteoarthritis

Osteoarthritis (OA) of the knee is the most common reason for a knee replacement. It can be primary or secondary:

  • Primary osteoarthritis:
    • Is not caused by previous damage or injury to the joint.
    • It is more common in people who have a close relative, particularly a brother or sister, with osteoarthritis.
    • It is more common as you get older and in people who are obese.
  • Secondary osteoarthritis:

Rheumatoid arthritis

Rheumatoid arthritis (RA) is a less common cause and knee replacements for this reason are reducing. This is because the treatments for rheumatoid arthritis have improved.

Other

Any condition that can cause damage to the cartilage of the knee might result in needing a knee replacement, such as:

  • Haemophilia.
  • Sero-negative arthritis.
  • Avascular necrosis.
  • Gout.

Further reading and references

HelloI am 5 weeks post bilateral knee replacement and feeling so frustrated with how slow my recovery seems to be going. I am 50 and totally underestimated just how big a deal this was going to be. I...

richellekramer
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