Pain, of any type, which does not let up, can be upsetting for any patient.

A painful knee can be very upsetting, as the joint is used in many activities that we do! It being a slightly more complex joint, it is more often affected, by degenerative conditions, than for example the hip joint.

It is often the inflammatory component, of the knee condition, that can be the most uncomfortable. A disturbed night’s sleep, very soon becomes an issue, with all the problems that ensue from chronic sleep deprivation.

Sometimes in addition to taking medications, an injection into the knee joint may be of help.

Injections into the knee joint

The 3 most common substances used for intra-articular (injection into the joint) are steroids, hyaluronic acid and PRP (platelet rich plasma). The evidence for each of these type of injections is variable, with steroids, probably having the most evidence for being helpful in suppressing inflammation.

Ultimately however, these injections are unlikely to reduce the chances of the patient wishing to go forward for the joint replacement operation in the future. However, because symptoms do tend to oscillate, an injection given at the right time, may halt a “ peak “off symptoms and therefore may give the patient a longer period of time, with symptoms that may be deemed to be “acceptable”.

Fortunately, the knee joint is just under the skin. An injection into the knee joint is therefore fairly straightforward, and often performed with the patient sitting on the side of the couch, and very rarely does it need any form of anaesthetic. If performed carefully it is not dissimilar in discomfort, from having a blood test.

A steroid injection into the knee joint contains both a short and long acting anaesthetic as well as the active ingredient which is a long acting steroid. Typically an early indication of possible success, is suggested, if the knee pain disappears shortly after the injection. This initial pain relief will only last for as long as the long acting anaesthetic lasts, and this is usually between 6 to 8 hours.

It takes between 10 days to a couple of weeks for the steroids to start kicking in, and the results should improve up to between 6 to 8 weeks, with hopefully the maximum effect shortly after. If an injection is considered successful and the pain relief has been long lasting, then clearly it is worth repeating that, on a subsequent occasion. If however the pain returns pretty promptly within a period of 3 months, then unfortunately the chances are, that any further injection, are unlikely to be successful.

For injections with hyaluronic acid it may well be that several injections are required to get the desired result. Injections with platelet rich plasma (PRP) behave a bit more like a steroid injection.