The kneecap (patella) lies in a large tendon from the thigh muscles (quadriceps) which help to straighten the knee.

The back of the kneecap is covered with smooth cartilage which helps it move smoothly over the lower part of the thigh bone (femur) when you straighten your leg.

Wear and tear (arthritis) can cause this smooth cartilage to gradually roughen and become thinner causing pain at the front of your knee.

In addition to arthritis, the knee cap can also be susceptible to instability or can frankly dislocate following an injury.


  • Pain – particularly at the front of the knee, around or behind the kneecap
  • Swelling – around kneecap
  • Grating or grinding sensation (crepitus)
  • Instability – the knee cap feels like it comes out of joint or dislocates

Both knees may be affected to some degree.


Several factors can be responsible for wear and tear at the back of the kneecap or instability including increased physical activity, pre-existing abnormal anatomy and previous knee injuries. Often, patients present with both pain and instability.


  • Rest – avoid strenuous use of knee
  • Physiotherapy – to strengthen the muscles around the hip and knee
  • Knee support or braces
  • Painkillers: paracetamol and non-steroidal anti-inflammatory medicines should be used with guidance from your general practitioner or pharmacist
  • Steroid injection

Non-surgical treatment is effective in many cases but some patients will require surgery to manage anterior knee pain or instability.