Intra-Articular Joint Injection

Each joint is enclosed in a capsule lined by a thin membrane that produces lubricating fluid. In arthritis, this lining can become inflamed and the cartilage worn, causing pain, stiffness and swelling. An intra-articular injection puts a medicine into the joint space itself, so it acts where it is needed and in higher concentration than a tablet could achieve, with less effect on the rest of the body. Corticosteroids, often mixed with a local anaesthetic, reduce inflammation and swelling. Hyaluronic acid, also called viscosupplementation, aims to improve the cushioning and lubricating quality of joint fluid, mainly in knee osteoarthritis. Platelet-rich plasma, or PRP, is made by spinning a sample of your own blood to concentrate the platelets, which carry growth factors, and injecting them into the joint. When a joint is swollen, fluid can first be drawn off through the same needle, called aspiration, which relieves pressure and lets the fluid be checked for crystals or infection.

Joint injections are considered when a joint stays painful or swollen despite simple measures such as exercise, weight management, painkillers and anti-inflammatory medicines, or when these medicines are unsuitable. Osteoarthritis of the knee, hip, shoulder, thumb base and other joints is the usual reason, particularly during a flare. In rheumatoid arthritis, psoriatic arthritis and other inflammatory conditions, a steroid injection can settle one or a few active joints quickly while longer-term medicines take effect. Gout and pseudogout attacks respond well to drainage and steroid injection once infection has been excluded. A steroid injection into the shoulder joint is also used for frozen shoulder, to ease pain and support physiotherapy. Injections can help people who wish to delay surgery or who are not fit for it, and a numbing injection can sometimes confirm which joint is the source of pain. They are not used when the joint or the skin over it may be infected, and they are rarely appropriate in a joint that has already been replaced.

You sit or lie in a position that opens the joint, and the skin is cleaned thoroughly with antiseptic. A small amount of local anaesthetic may be injected into the skin first. For joints that are easy to feel, such as the knee, the needle can be placed using landmarks, but many clinicians use ultrasound guidance, which shows the needle entering the joint on a screen. Guidance improves accuracy, especially for deep joints such as the hip, for the shoulder and for small joints of the hand and foot; X-ray guidance is used for some joints. If there is excess fluid, it is drawn off first and may be sent to the laboratory. The medicine is then injected slowly, the needle removed and a small dressing applied. For platelet-rich plasma, a blood sample is taken and processed for about 15 to 30 minutes beforehand. Hyaluronic acid may be given as a single injection or as a course of three to five weekly injections, depending on the product. The visit usually takes about 10 to 20 minutes.

A good candidate has a diagnosed joint condition, ideally confirmed by examination and imaging such as X-ray or ultrasound, and pain or swelling that limits daily life. The clinician checks for signs of infection in the joint or skin, which would rule out injection, and asks about recent injections, as steroid injections into the same joint are usually limited to a few per year. People with diabetes should know that a steroid injection can raise blood sugar for a few days and should monitor it more closely. Blood thinners usually do not need to be stopped, but tell the team if you take them. If you have a bleeding disorder, an allergy to local anaesthetic or a joint replacement, discuss this first. There is no need to fast, and you can usually drive home after a lower limb injection, although arranging a lift is sensible. For international patients, recent X-rays or scans can be reviewed remotely before travel.

Recovery is short. The joint may feel numb for a few hours if local anaesthetic was used, and it is sensible to rest it for about 24 to 48 hours, avoiding running, heavy lifting or long walks, before gradually returning to normal activity. Some people have a temporary increase in pain for a day or two, sometimes called a post-injection flare, which settles with ice and simple painkillers. Steroid injections often start to help within a few days, while hyaluronic acid and platelet-rich plasma usually take several weeks to show an effect. Because recovery is so brief, flying home the same or the next day is usually fine, with short walks during a long flight. Travel for an injection makes sense mainly as part of a wider specialist assessment that combines diagnosis, guided injection, a review of other treatment options and a written exercise plan. Repeat injections, if needed later, can usually be given near home following the treating team's advice.

Joint injections are common and generally safe, but they are not free of risk. The most important, though rare, complication is infection inside the joint, which causes increasing pain, heat, swelling and fever in the days afterwards and needs urgent medical attention. Other possible effects include a short flare of pain, bruising, facial flushing for a day or two after a steroid, a temporary rise in blood sugar and, occasionally, thinning or lightening of the skin at the injection site. Repeated steroid injections into the same joint may contribute to cartilage loss over time, which is one reason their number is limited. Hyaluronic acid can cause temporary swelling of the joint, and platelet-rich plasma often causes soreness for a few days. Results vary. Steroid relief usually lasts weeks to a few months. Studies of hyaluronic acid and platelet-rich plasma show mixed results, partly because products and preparation methods differ, so the benefit for any one person is hard to predict.