Knee Osteoarthritis
Knee care in Ware, Hertfordshire
Your knee hurts on the stairs, physiotherapy has taken it only so far, and you want to know what is actually left to try.
Start with what your knee is stopping you from doing
Start with your knee
Does this sound familiar?You do not need to know what treatment you want before getting in touch.
Asking a question costs nothing and does not commit you to treatment.
Knee osteoarthritis
Knee osteoarthritis is damage to the surfaces inside the joint, causing pain, stiffness and swelling.
At Sonoscope in Ware, Hertfordshire, Rob Mast examines your knee, scans it and treats it in a single visit.
Ultrasound-guided injections start at £250. This covers the examination, the scan, the injection and a written report.
What osteoarthritis does to a knee
The cartilage covering the ends of the bones grows thinner and rougher. The bone underneath thickens in response, and small bony spurs called osteophytes form around the edges of the joint. The joint lining can produce extra fluid, so the knee swells. That swelling is the joint trying to repair itself, not simply the result of use.
Pain usually shows up on movement rather than at rest. Stiffness tends to be worst first thing and after sitting still, then clears within half an hour. Some knees click or grind as they bend.
Night pain is more common than most people realise. Somewhere between 60% and 80% of people with knee osteoarthritis report pain that disturbs their sleep, and the two feed each other, because a broken night leaves you more sensitive to pain the following day. If your knee has started waking you, that is usually the point at which people stop putting off doing something about it.
There is a second effect worth knowing about. When a knee hurts, the thigh muscles above it weaken, and a weaker thigh leaves the joint less supported, so the knee can feel unstable or give way under load. That is why strength work sits at the centre of everything below.
Here is the part that surprises people. Osteoarthritis does not march steadily downhill. NICE describes symptoms that fluctuate, with flare-ups that arrive and then settle again. A bad month is not evidence that next year will be worse, and plenty of knees stay much the same for years.
Age over 50, a previous knee injury, extra body weight and a family history all raise the odds of developing it. None of them settle how it turns out.
Imaging and diagnosis
Plenty of people arrive holding an X-ray report and a phrase somebody gave them: bone on bone.
That phrase carries more weight than it deserves. NICE guidance notes there is often a poor link between what shows on imaging and how a knee actually feels. Minimal changes on a scan can sit alongside severe pain. Substantial changes can produce almost none.
Which is why most knees are diagnosed without any imaging at all. The NICE osteoarthritis guideline advises diagnosing osteoarthritis clinically in anyone aged 45 or over with activity related joint pain, provided there is either no morning stiffness or stiffness that clears inside 30 minutes. Blood tests add nothing either, because osteoarthritis does not alter blood results.
So a poor X-ray on its own is not a reason to inject a knee, and it is not a reason to operate on one. What counts far more is how much the knee limits what you do, and what is happening inside it right now.
Where injections fit
There is no rigid five-step ladder that every knee has to work through. The useful question is whether pain is getting in the way of progress, and whether an injection is appropriate for your knee, now.
A treatment worth discussing
A knee injection is not there to replace everything else. Its value is often in reducing pain enough to make day-to-day movement, walking and strength work more manageable.
Some knees respond better than others. Drawing off fluid before the injection is linked to a better result, which is why a swollen knee is drained first. Ultrasound guidance places the medicine inside the joint capsule rather than the fat pad or the joint lining. And knees with troublesome symptoms, but without end stage damage, tend to show the clearest improvement (Maricar and others, 2012).
Building the muscles around the knee remains important. Where pain has been blocking that work, relief can make it easier to resume.
Where there is weight to lose, even a modest reduction changes the load passing through the knee during walking and stairs.
Anti-inflammatory treatments may still have a role where they are appropriate and safe for you.
Surgery is a separate decision further down the line. Keyhole washouts are not recommended as treatment for osteoarthritis. Where joint replacement eventually becomes appropriate, partial or full knee replacement may be discussed.
Treatment options
A corticosteroid calms inflammation inside the joint. Relief usually arrives within a few days and can last for several months. This is the option when you need a window to get moving again.
Read about steroid injectionsA hyaluronic acid gel injected into the knee acts as a lubricant rather than as a drug. Worth knowing before you choose it: NICE advises against hyaluronan injections for osteoarthritis, because the evidence across trials is inconsistent. Many patients still choose it, usually because steroid gave them little, or because they would rather avoid steroid. Rob will say whether it suits your knee.
Read about hyaluronic acid injectionsA single injection hyaluronic acid product, working on the same principle as Ostenil Plus with a different formulation. The NICE caveat above applies to it equally. If you are weighing the two families against each other, we have written separately on which of the two gives longer relief.
Compare steroid and hyaluronic acidA permanent hydrogel implant for the knee that cushions the joint rather than treating inflammation, given as one injection. NICE considered it for evaluation and did not select it, so it is not routinely available on the NHS.
Read about ArthrosamidThe swollen knee
The most commonly wasted appointment is the swollen knee.
Not every swollen knee is a full one, though. Soft swelling is fluid and can be drawn off.
Can be drainedHard swelling is bone, where the osteophytes at the joint margins have made the knee look and feel bigger, and no needle will change that. Telling the two apart by hand is difficult. On a scan it takes seconds.
Not drainableBehind the knee
Some of the fluid tracks backwards and gathers behind the knee. That is a Baker's cyst, which is the joint capsule bulging rather than a separate problem in its own right. A large, painful one can be drained in the same appointment.
Process steps
From examination to written report, the assessment, diagnostic scan and treatment decision happen in one visit.
Rob takes your history and examines the knee. Bring any imaging you already have, although you do not need any to attend.
The knee is scanned there and then. At the knee, the scan changes the decision more often than it changes the needle, because it shows whether the pain is arthritis, fluid, a cyst or something else entirely.
Where it is the right step, the injection goes in under live imaging. Fluid is drawn off first if the scan shows it.
You leave with a report naming what was found, what was used and what to do next.
No GP referral needs arranging. Rob is an independent prescriber, which means he prescribes the injectable medicine himself and takes one appointment out of the process.
Pricing
Prices last updated 27 July 2026.
Diagnostic ultrasound scan, no injection
£150Steroid injection
£250Ostenil Plus hyaluronic acid
£300Durolane hyaluronic acid
£350Arthrosamid
£2,300Every injection fee covers the clinical examination, the diagnostic scan, the injection itself and the written report. Nothing is added afterwards. The fee stays the same whichever joint is treated, so a knee costs what a thumb costs.
Should the scan show an injection is not suitable, you pay for the examination, scan and report only. You can see every published fee for the full list.
About and credentials
Every injection at the clinic is performed by Rob Mast personally.
He is an Advanced Practice Physiotherapist and musculoskeletal sonographer, registered with the HCPC under PH47036, holding a CASE accredited postgraduate certificate in musculoskeletal diagnostic ultrasound. Alongside the clinic he works as an interventional MSK sonographer in an NHS radiology department, and teaches on the ultrasound guided injection programme at Brunel University.
Guidance matters more at some joints than at others. Across 184 patients injected at the shoulder, elbow, wrist, knee or ankle, accuracy reached 83% with ultrasound and 66% without it. A knee is one of the easier targets to reach by feel, which is exactly why the scan earns its place here through what it tells you rather than through where it puts the needle.
Scope and appropriateness
Every appointment starts with an examination and diagnostic scan, so treatment is based on what is actually found in your knee.
Where the scan shows that a different treatment or service would suit the findings better, Rob will explain what has been found and recommend the appropriate next step. You still leave with a completed examination, a diagnostic scan, a written report and a clear answer about what is actually causing the problem, which is often the thing people wanted most.
When another service is more appropriate
Before you book
Clear answers about repeat injections, ultrasound, referrals, knee replacement and what happens if treatment does not help.
A single steroid injection into an arthritic knee is a well established treatment and is not considered to damage cartilage. The concern applies to frequent repetition into the same joint over years, which is why spacing matters and why repeat injections are limited. Rob will tell you how long to leave between them.
There is no single figure that fits everybody. Steroid injections generally become less effective the more often they are repeated, and side effects accumulate. In practice the gap is measured in months rather than weeks, and it is set case by case.
Longer than most people are told. Registry data covering 299,000 knee replacements shows roughly 93% still in place at 15 years, 90% at 20 years and 82% at 25 years. Partial replacements sit lower, at around 70% at 25 years. The commonly quoted 15 year figure reflects implants from an earlier era.
No. You can contact the clinic directly and book. Bring any scans or X-rays you have had elsewhere, although they are not required.
It shows a great deal of it. Ultrasound picks up joint fluid, osteophytes around the joint edges and thickening of the joint lining. It cannot see through bone, so it does not replace an X-ray in every situation, though it answers the questions that change what happens on the day.
That outcome is worth planning for. Where a steroid injection gives little relief, that is useful information in itself, and it often points towards hyaluronic acid, Arthrosamid, or a conversation about surgery. The report you leave with sets out what follows.
What happens next
Most people picture this as a cliff edge. Carry on until nothing works at all, then have the knee replaced.
It rarely runs that way. NICE advises deciding on a replacement from clinical assessment, meaning how much the knee is affecting your life, rather than from a score or an X-ray grade. Age, weight, sex and smoking are not grounds for exclusion. And because modern replacements last considerably longer than that old 15 year figure implied, holding off no longer protects you the way it once appeared to.
Which makes the real question an injection answers a question about timing. It can buy back a summer, or a season of something you had given up, while you decide.
