Knee joint injection is a procedure to inject medication into the knee — most commonly corticosteroid for anti-inflammatory effect or hyaluronic acid (viscosupplementation) for lubrication and symptom relief in osteoarthritis.
The skin over the knee is cleaned. Local anaesthetic may be applied. A needle is inserted into the joint — commonly through a superolateral (above and to the outside) or infrapatellar approach. For corticosteroid: a mixture of steroid and local anaesthetic is injected. For hyaluronic acid: a viscous gel is injected. The procedure takes five to ten minutes and is performed in clinic.
Corticosteroid: for inflammatory flares of osteoarthritis, rheumatoid arthritis, gout, and other causes of knee swelling and pain. Hyaluronic acid: for mild to moderate knee osteoarthritis when oral medications and physiotherapy have provided insufficient relief. Both are also used as diagnostic tools.
Oral anti-inflammatory and pain medication, topical treatments, physiotherapy, weight management, knee bracing, activity modification.
No special preparation. Inform the clinician about blood-thinning medications and any allergies.
Corticosteroid: rapid pain relief within 24–72 hours, lasting weeks to months. Hyaluronic acid: more gradual improvement over two to four weeks, potentially lasting six to twelve months. Response varies significantly between patients.
Brief pain during the injection.
Temporary increased pain for 24–48 hours (corticosteroid).
Not all patients respond.
Joint infection. Risk approximately 1 in 10,000 to 1 in 50,000.
Lightening of skin at injection site (corticosteroid).
Loss of subcutaneous fat.
Evidence suggests frequent corticosteroid injections may accelerate cartilage loss. Limit to two to three per year.
To the injected substance. Very rare.
No anaesthesia needed beyond local anaesthetic at the injection site.
Rest for 24–48 hours. Avoid strenuous activity for a few days. If the injection helps, intensify physiotherapy to maximise the benefit of the pain-free window.
Assess response at two to four weeks. Plan further management based on response.
Most clinicians limit corticosteroid injections to two to three per year per joint. Hyaluronic acid courses can be repeated every six to twelve months.
Injections can provide meaningful symptom relief for months to years, potentially delaying surgery. However, they do not halt the underlying arthritis.