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Knee Injections in Bath & Bristol (Steroid, Hyaluronic Acid, PRP, Arthrosamid)

Knee injections can reduce pain and inflammation, improve movement, and help you progress with physiotherapy. They can be particularly useful for knee osteoarthritis, flare-ups of synovitis (joint lining inflammation), and some tendon or bursa-related pain around the knee. However, injections are not a “cure” for arthritis and they do not repair torn cartilage or ligaments.

Mr Simon Abram, Consultant Specialist Knee Surgeon, offers specialist assessment and treatment planning in Bath and Bristol. If an injection is suitable, the choice of injection is tailored to your diagnosis, severity, activity goals, and medical history, with a clear discussion of expected benefit, limitations, and alternatives.

What can knee injections help with?

  • Knee osteoarthritis pain (especially flare-ups that limit exercise and walking)
  • Inflammation and swelling (synovitis or reactive effusions, especially where pain is stopping rehabilitation)
  • Bridging treatment while waiting for rehabilitation to work, imaging, or surgery
  • Salvage treatment where a patient may be medically unfit or unsuitable for surgery

What injections cannot do

  • They do not “regrow” knee cartilage in advanced arthritis
  • They cannot fix knee instability from a ligament tear (e.g. ACL rupture)
  • They may reduce symptoms but will not underlying mechanical damage or alignment problems

How we decide which injection (if any) is right for you

The best injection depends on the underlying problem. A careful assessment usually includes your symptom pattern, examination findings, and imaging where appropriate (X-ray or MRI). The most important question is: what are we trying to achieve?

  • Fast short-term relief to settle a flare and enable physiotherapy (often steroid +/- hyaluronic acid)
  • Medium-term symptom improvement for mild-to-moderate osteoarthritis where rehabilitation needs support (such as PRP or hyaluronic acid, but varies by injection type)
  • Longer-acting symptom control in selected osteoarthritis cases (some patients consider Arthrosamid)

If your knee is very swollen, sometimes fluid aspiration (removing fluid) can be combined with injection to reduce pressure and improve comfort.

Steroid (Corticosteroid) Knee Injection (e.g. Depo-Medrone)

What it is: A corticosteroid injection reduces inflammation within the joint. Depo-Medrone (methylprednisolone) is one commonly used option; other steroids are also used in knee practice.

Best for: inflammatory flare-ups, painful swelling, osteoarthritis exacerbations that are preventing exercise and function.

What results to expect

  • Often works quickly (within a few days), although it can take up to 1–2 weeks
  • Typically provides short-term relief (often weeks rather than many months)
  • Most effective when paired with rehabilitation and strength rebuilding

Important considerations

  • Repeated steroid injections are usually limited, particularly in the same joint, and should be part of a wider plan rather than the only strategy
  • People with diabetes may see a temporary rise in blood sugars for a few days
  • Injections are avoided if there is a concern about infection or significant skin breakdown near the injection site
  • Steroid flare: it is common to get a short term (1-2 days) or worsening symptoms. This should settle and if it does not or your feel unwell at the same time, urgent medical attention should be sought.

Hyaluronic Acid (Viscosupplementation) Knee Injection

What it is: Hyaluronic acid is a gel-like substance intended to improve lubrication within the knee joint. It is sometimes described as “viscosupplementation”.

Best for: selected cases of mild-to-moderate knee osteoarthritis where other measures have not given adequate relief, and where an individual trial is considered appropriate.

What results to expect

  • Benefits (if it helps) are usually gradual, often taking several weeks
  • Some protocols use a single injection; others use a course of injections (depending on product)
  • Response is variable–some patients report meaningful improvement, others little change

UK relevance (what you should know)

  • In the UK, hyaluronic acid injections are not routinely recommended for osteoarthritis in national guidance
  • They may still be discussed in private practice for carefully selected patients, with realistic expectations and a clear plan for what happens if it does not help

PRP (Platelet-Rich Plasma) Knee Injection

What it is: PRP is made from your own blood. A small blood sample is taken and processed to concentrate platelets and associated growth factors, then injected into the knee. It is most often used for mild-to-moderate knee osteoarthritis and selected tendon problems.

Best for: patients looking to support symptoms and function without surgery, particularly in earlier osteoarthritis, where the main goal is to improve pain and knee tolerance for activity and rehabilitation.

What results to expect

  • Improvement (if it helps) is usually not immediate and may take 4–12 weeks
  • Some patients have a short-term pain flare for a few days after injection
  • Often delivered as a course (commonly 2–3 injections), depending on your plan

Important considerations

  • Evidence is mixed and outcomes vary between patients
  • PRP is usually not a first-line NHS treatment for knee osteoarthritis and is more commonly discussed in private care
  • After PRP, many clinicians advise avoiding anti-inflammatory medicines for a short period around the injection, because they may interfere with the intended biological response

Arthrosamid (Polyacrylamide Hydrogel) Injection

What it is: Arthrosamid is an injectable hydrogel used for knee osteoarthritis. It is designed to be longer-acting than standard injections by integrating with the joint lining and helping reduce symptoms over time. It is typically offered as a single injection.

Best for: selected patients with osteoarthritis pain and reduced function who want a longer-acting non-surgical option, particularly when physiotherapy and simpler measures have not been enough and surgery is not yet desired (or is being delayed).

What results to expect

  • Improvement (if it helps) is usually gradual over weeks
  • Studies suggest benefits can last longer than many other injections in some patients, but response varies
  • It is not a cartilage-regrowth treatment; it is a symptom and function treatment

Important considerations

  • Arthrosamid is intended as a longer-acting injectable option, so patient selection and counselling are particularly important
  • Because it is designed to remain in the joint it is a type of implant - it is not approached in the same way as short-acting injections and only offered in highly selected cases with careful counselling
  • It does not prevent patients from eventually needing knee surgery, but may help some people delay it or to better manage their symptoms

What happens on the day of a knee injection?

  • The skin is cleaned carefully using sterile technique
  • The injection is performed into the knee joint (sometimes after fluid aspiration if the knee is swollen)
  • In many cases, ultrasound guidance may be used to improve accuracy, especially in complex or previously operated knees
  • You can usually walk out afterwards and go home the same day

Aftercare: what to do after an injection

  • Keep activity light for 24–48 hours (normal walking is usually fine)
  • Avoid heavy gym work, running, or sport for a few days (your plan may vary by injection type)
  • Use simple pain relief if needed, and ice can help with temporary soreness
  • Restart or continue physiotherapy as advised–injections work best when they enable stronger rehab

Risks and side effects (all knee injections)

Complications are uncommon, but it is important to understand them:

  • Infection (rare, but serious): increasing redness, heat, fever, and worsening pain should be assessed urgently
  • Post-injection flare: temporary increase in pain and swelling for 24–72 hours
  • Bleeding/bruising: more likely if you bruise easily or take blood-thinning medication
  • Allergic reaction (uncommon)
  • Vasovagal episode: feeling faint during or after the injection

Specific considerations by injection type

  • Steroid: temporary blood sugar rise in diabetes; rare skin thinning or colour change at the injection site
  • Hyaluronic acid: occasional inflammatory reaction with swelling and pain (rare)
  • PRP: short-term soreness or flare is relatively common; results can take longer to appear
  • Arthrosamid: temporary swelling or discomfort can occur; careful patient selection and counselling are important because it is designed to be longer-acting. Antibiotics must be given with the injection.

Frequently asked questions

Which injection is “best” for knee osteoarthritis?

There isn’t one best injection for everyone. Steroid injections can help short-term flare-ups; PRP may help some people with earlier osteoarthritis; hyaluronic acid has mixed results and is not routinely recommended in UK guidance; Arthrosamid is designed as a longer-acting option for selected patients. The right choice depends on your diagnosis, severity, goals, and medical history.

How quickly will I feel better?

Steroid often acts within days. PRP and Arthrosamid are typically slower and can take weeks to show benefit. Hyaluronic acid (if it helps) is usually gradual rather than immediate.

How long do knee injection benefits last?

Duration varies between people and injection type. Steroid is usually short-term. Other injections may last longer in selected patients, but results vary and they work best as part of a wider plan including exercise and weight management where appropriate.

Can injections replace surgery?

Sometimes injections help you manage symptoms well enough to avoid or delay surgery. If the knee has advanced arthritis or major mechanical problems, injections may provide limited relief and surgery may still be the best long-term option.

Can I have a knee injection in Bath or Bristol?

Yes. Mr Simon Abram offers specialist assessment and treatment planning in Bath and Bristol, including discussion of the most appropriate injection type (or whether an injection is unlikely to help), with a clear plan for rehabilitation and next steps.

Related knee topics

This information is general and does not replace an individual consultation. If you develop increasing redness, heat, fever, or severe worsening pain after an injection, seek urgent medical assessment.