What happens during a knee injection, and does it hurt?

Before the injection

The doctor confirms the diagnosis, checks your medicines and allergies, and asks about diabetes, blood thinners and any recent infection. You should mention if you feel unwell that day. The type of injection, whether steroid, hyaluronic acid or PRP, is agreed in advance, along with what it can and cannot do. For PRP, a small blood sample is taken from your arm and prepared first.

Step by step

• You lie or sit with the knee supported, usually slightly bent or straight
• The skin is cleaned carefully with antiseptic to reduce infection risk
• Local anaesthetic spray or a small numbing injection may be used
• The needle is placed into the joint, sometimes with ultrasound guidance for accuracy
• If the knee is swollen, fluid may be drawn off first
• The medicine is injected and a small dressing applied

How much does it hurt?

Most people describe a sharp pinch and a feeling of pressure or fullness in the knee. It is usually over within a minute. Relaxing the thigh muscle helps the needle pass smoothly, so slow breathing genuinely makes a difference. Some people have an ache for a day or two afterwards, and PRP in particular can cause a short flare of soreness. Severe pain at the time is uncommon.

Afterwards

You are usually observed briefly and then walk out. Someone driving you home is sensible if the knee feels heavy or numb. You are given written advice on activity, ice and which symptoms should prompt a call. Increasing redness, heat, swelling or fever in the days after an injection needs urgent review, as infection, although rare, must be excluded.