Knee injection treatments

An injection places medication directly into the knee joint, or into a specific structure around it. Because the medication goes where it is needed, a smaller dose can be used than with tablets, and side effects elsewhere in the body are reduced.

Injections are generally used for one of three reasons.

To control pain and inflammation, where symptoms are limiting daily life and other measures have not been enough.

To allow rehabilitation to begin. Pain can prevent someone doing the exercise that would improve their knee. Settling that pain creates a window in which physiotherapy becomes possible. This is often the most valuable use of an injection.

To help with diagnosis. Where it is unclear whether pain is coming from inside the joint or from a structure around it, the response to a targeted injection can help clarify the source.

The most commonly used knee injection. A steroid, usually combined with local anaesthetic, is injected into the joint to reduce inflammation.

The local anaesthetic often gives immediate relief lasting a few hours. The steroid takes a few days to take effect.

NICE advises that corticosteroid injections may be considered for osteoarthritis when other treatments are ineffective or unsuitable, or to support therapeutic exercise, and that patients should be told the relief is short-term, in the range of two to ten weeks.

Some people get considerably longer benefit than that, and some get very little. Repeated injections into the same joint are generally limited, as frequent steroid use may have adverse effects on cartilage.

Also known as viscosupplementation. Hyaluronic acid is a component of normal joint fluid, and these injections aim to improve lubrication within the joint.

The evidence is contested and UK guidance is clear. NICE recommends that intra-articular hyaluronan injections should not be offered to manage osteoarthritis, having found insufficient evidence of meaningful benefit in pain, function or quality of life, alongside cost-effectiveness considerations.

Some clinicians and international bodies take a different view, and these injections continue to be used in private practice. If hyaluronic acid is discussed with you, you should be told what the UK guidance says so that you can make an informed choice.

A sample of your blood is taken and spun in a centrifuge to concentrate the platelets, which are then injected into the knee.

Interest in this treatment is considerable, but the evidence remains limited. A large network meta-analysis of intra-articular treatments for knee and hip osteoarthritis found that no injection treatment produced a clinically meaningful improvement in pain or function compared with placebo at three to six months, with corticosteroid providing short-term relief that typically waned after four to six weeks, and hyaluronic acid and platelet-rich plasma showing inconsistent and modest effects that were not sustained.

Platelet-rich plasma is not currently recommended by NICE for routine treatment of knee osteoarthritis. It should be presented as a treatment where the evidence is still developing rather than as an established one.

Arthrosamid is an injectable gel used to treat pain from knee osteoarthritis. It is made of polyacrylamide hydrogel, which is water and a stable, non-biodegradable polymer. It is injected into the knee joint, usually as a single treatment.

The gel is thought to integrate into the lining of the joint, which helps cushion the joint and reduce pain and stiffness. Unlike steroid or hyaluronic acid injections, which tend to wear off within weeks or months, Arthrosamid is designed to give longer-lasting relief, and studies have reported benefits lasting a year or more for many people.

It is generally suited to people with mild to moderate knee osteoarthritis who haven't found enough relief from other treatments. Common side effects include temporary pain, swelling or stiffness at the injection site. Less commonly, joint infection or inflammation can occur.

Arthrosamid is not currently available on the NHS, so it must be arranged privately.

Rest the knee for the first day or two, avoiding strenuous activity and heavy loading.

With a steroid injection, some people notice increased pain for a day or two before it settles. This is common and not a sign that something has gone wrong. It usually responds to ice and simple pain relief.

Once symptoms have settled, use the window the injection provides. Begin or resume physiotherapy, build strength, and increase activity gradually. An injection that is used to enable rehabilitation achieves considerably more than one that is not.

Mr John Lynch will advise on timescales for returning to specific activities.

Steroid injections into the same joint are usually spaced several months apart, and there is generally a limit on how many are given, because repeated use may affect the cartilage and because the benefit often reduces with each one.

If an injection gives good but short-lived relief, and the pattern repeats, that is usually a sign that the underlying problem needs addressing rather than that more injections are the answer.

Mr John Lynch will discuss how injections fit into your overall treatment rather than treating them as an isolated intervention.