The knee joint is actually made up of three separate parts. At the front of the knee joint is the kneecap or patellofemoral joint. The main part of the knee is made up of the medial and lateral tibio-femoral joints. The patello-femoral joint can develop arthritis with the other parts of the knee still in good condition. We call this patellofemoral arthritis or kneecap arthritis. It appears to be more common in women, and can often be associated with kneecap problems from young adulthood.
The shape of some peoples knees can make them more prone to this. If the kneecap is too high, too low, lies more towards the outside of the knee, or in knock kneed (valgus knees) individuals this problem is more likely.
You will experience pain at the front of the knee. Going up and down stairs can often be very painful and difficult. Sitting for long periods of time can be painful (the so called theatre-goers sign). The knee may swell. You may experience clicking and crunching from under the kneecap. Kneeling will be particularly painful, and getting up from a squatting position may be painful and noisy.
If you think you have this condition it's well worth getting it checked out by Mr Willis-Owen. A careful physical examination and a series of x-rays will usually confirm the diagnosis. Sometimes physiotherapy to improve the muscles around the knee and particularly in the VMO muscle can help. Injections into the knee can be useful in the early stages. Keyhole surgery (arthroscopy) can be helpful to tidy up the worn cartilage if you have it seen to early enough. Sometimes keyhole procedure called a lateral release is useful.
For severe kneecap arthritis knee replacement (arthroplasty) may be required. There is a choice between replacing just the kneecap joint, or the whole knee joint. This is a complicated decision, and is best discussed with Mr Willis-Owen. Kneecap joint replacements tend to perform better, but last less time than total knee replacement so the decision should be weighed up against many factors.