What is a knee injection?
A knee injection places medication directly into or around the knee to reduce pain and help you move. The three most common types are:
- Steroid (cortisone): a strong anti-inflammatory for inflamed or arthritic knees
- Hyaluronic acid (Ostenil): a gel-like lubricant for osteoarthritis
- PRP: platelet-rich plasma made from your own blood
Here every injection is given under ultrasound guidance, after a diagnostic scan.
Which knee injection is best?
It depends on what is causing the pain. Steroid works fastest for an inflamed or swollen knee. Ostenil is a non-steroid option for osteoarthritis that often lasts longer. PRP aims to support healing and suits some people with mild to moderate osteoarthritis or tendon problems. Your consultant recommends one after the scan.
Do knee injections work for arthritis?
For many people, yes. A steroid injection often eases arthritis pain for weeks to months, and hyaluronic acid can help for six to twelve months. Injections manage symptoms rather than reverse arthritis, so they work best alongside exercise and weight management. In severe, bone-on-bone arthritis the benefit is often shorter.
Do knee injections hurt?
Most people find them far easier than expected. Local anaesthetic numbs the skin, so you feel a small sting, then pressure as the medication goes in. Because the needle is guided by ultrasound, it reaches the target in one accurate pass. The knee may ache for a day or two afterwards.
How long does a knee injection take to work?
The local anaesthetic can ease pain within minutes, but wears off after a few hours. A steroid usually starts working within a few days, with the full effect at one to two weeks. Ostenil builds over a few weeks, and PRP over several weeks to two or three months.
How long do knee injections last?
A steroid injection typically helps for several weeks to a few months, sometimes longer. Ostenil commonly lasts six to twelve months. PRP can last several months in mild to moderate osteoarthritis. How long relief lasts depends on the cause and how advanced it is.
How many steroid injections can I have in my knee?
Usually no more than three or four a year in the same knee, spaced at least three months apart. Repeated steroid injections over a long period may affect cartilage, so your consultant plans treatment carefully and discusses other options if the effect gets shorter.
What are the side effects of a steroid knee injection?
Most people have none. Common, short-lived effects include a flare of pain for a day or two, facial flushing, trouble sleeping for a night or two, and a temporary rise in blood sugar in people with diabetes. Infection is rare, especially with sterile, ultrasound-guided technique.
Can a knee injection make the pain worse?
Some people have a short flare of pain for 24 to 48 hours after a steroid injection, and PRP often causes soreness for two to three days. This settles with rest, ice and paracetamol. If the knee becomes hot, red and increasingly painful, or you develop a fever, call us the same day, as this can rarely be an infection.
What should I do after a knee injection?
Rest the knee and avoid running, heavy lifting or high-impact exercise for 24 to 48 hours (a few days after PRP), then build up gradually. You can walk normally straight away. A cold pack and paracetamol help with any soreness. After PRP, avoid anti-inflammatory painkillers for a week.
Should knee injections be ultrasound guided?
We think so. Injections given by feel can miss the joint or the target, so the medication ends up in surrounding tissue. Under ultrasound, your consultant watches the needle reach the joint, bursa or cyst before anything is injected, which tends to be more accurate and more comfortable.
How much does a knee injection cost?
At Harley Street Ultrasound a steroid knee injection is £525, a PRP knee injection £545, and an Ostenil injection £645, all fees inclusive: the consultant assessment, diagnostic ultrasound, the guided injection, local anaesthetic and your written report. If the scan shows an injection is not right, you pay the diagnostic scan rate instead.
Are knee injections available on the NHS?
Steroid knee injections are available on the NHS, usually after a GP or physiotherapy assessment and sometimes with a wait. Hyaluronic acid and PRP are not routinely offered on the NHS for knee osteoarthritis. Privately, you can be scanned and treated by a consultant in one visit, usually within days.
What happens if I don’t need an injection?
We will never give you an injection you do not need. Every appointment starts with a diagnostic ultrasound of your knee, and if your consultant decides an injection is not the right treatment, it simply does not go ahead. You are charged our standard diagnostic ultrasound rate, not the treatment price.
You still leave with a clear plan: physiotherapy, a different treatment, an MRI, or a referral to the right specialist, with your report and images on your secure portal.
Do I need a referral?
No. Harley Street Ultrasound is a private clinic, so you can book an ultrasound-guided knee injection in London directly, online or by phone: no GP letter and no waiting list. If you are searching for knee injections near me in central London, we are at 99 Harley Street, a short walk from Regent’s Park and Oxford Circus stations.
Prices are published before you book and are all fees inclusive: the consultant assessment, the diagnostic ultrasound, the guided injection, local anaesthetic and your written report. Insured patients should check with their insurer and bring an authorisation number if their policy requires one.
Will I get a report?
Yes. Your consultant explains the scan findings and the treatment in the room, and a written report with your images is published to your secure patient portal, usually the same day, ready to share with your GP, physiotherapist or surgeon.
Can I drive home afterwards?
Usually, yes: there is no sedation or general anaesthetic. The local anaesthetic can leave the area numb for a few hours, so if the injection is in your right leg or foot, or the joint feels weak, it is sensible to arrange a lift or take public transport.
Can I still use the NHS afterwards?
Yes: completely. Coming to us privately never affects your NHS care. Your report and images can be shared with your NHS GP or consultant, and if anything needs onward NHS care, your consultant writes to your GP so you re-enter the pathway with a diagnosis already in hand.
