Hyaluronic Acid Injections for Knee Osteoarthritis
Hyaluronic acid is a natural component of joint fluid that contributes to lubrication. In knee osteoarthritis, hyaluronic acid can be injected into the joint (viscosupplementation).
What does the research show?
Results are mixed. An earlier Cochrane review found benefits for pain and function [2]. A later large meta-analysis concluded that the benefit is small and of uncertain clinical relevance, with a possible increase in adverse events [1].
Further reading: the guide “Knee Osteoarthritis” and the articles PRP (Platelet-Rich Plasma) Therapy: What the Evidence Shows and Cell-Based Treatments for Knee Osteoarthritis: What the Evidence Shows.
What do guidelines say?
- The OARSI guideline gives a conditional recommendation, noting possible benefit beyond 12 weeks [3]
- The American College of Rheumatology guideline conditionally recommends against it [4]
Who may consider it?
It may be considered for selected patients with knee osteoarthritis who have not responded adequately to exercise and other first-line treatments, after discussion of the uncertain benefit. It does not replace exercise and weight management.
What knee osteoarthritis does to the joint
Osteoarthritis is a condition of the whole joint: the cartilage covering the bone ends gradually thins, the bone beneath it changes, small bony outgrowths (osteophytes) form and the joint lining can become inflamed. In osteoarthritis the hyaluronic acid in joint fluid becomes less concentrated and less viscous (less thick), which was the rationale for injecting it.
How the injection is given
The injection is given into the knee joint under sterile conditions, sometimes with ultrasound guidance to confirm the needle position. Depending on the preparation, a course may be a single injection or several injections given at weekly intervals. Any effect usually develops over weeks rather than immediately, and if it occurs it is temporary, so the question of repeat treatment arises.
Placing it in the bigger picture
Hyaluronic acid is not a first-line treatment. The foundation of care for knee osteoarthritis is:
- An exercise programme with strengthening of the thigh and hip muscles
- Weight management for people with excess weight
- Education and self-management, including pacing activities
- Topical or oral pain medicines as appropriate
Injections, if considered, are additions to this programme, not replacements. Because guideline recommendations differ and the size of benefit is uncertain, the decision should be shared between you and your doctor, considering your expectations, other conditions and costs.
Who is not suitable
Injection is generally avoided if there is skin infection around the knee, joint infection, or an allergy to components of the preparation. Bleeding disorders and blood-thinning medicines need to be discussed beforehand. Very advanced osteoarthritis may respond less well.
Home measures after an injection
- Avoid strenuous activity for a day or two, as advised
- Use ice for local discomfort
- Resume your exercise programme gradually
Red flags
Seek prompt assessment if, after an injection, the knee becomes increasingly hot, red, swollen and painful, or you develop fever. These can be signs of infection, which is rare but needs urgent treatment.
When to see your physical medicine and rehabilitation specialist
Seek assessment if pain is severe, keeps getting worse, wakes you at night or does not start to improve within a few weeks; if numbness, weakness or any warning sign appears; or if you are unsure what your test results mean. Your physical medicine and rehabilitation (PM&R) specialist, a doctor trained to diagnose and treat musculoskeletal and nerve problems without surgery, examines you, explains the findings and plans treatment together with the physiotherapist. Whether injections or other advanced treatments are suitable for you is decided by a PM&R specialist after examination. Prof. Dr. Engin Çakar works in this field and can be consulted online or in person; otherwise, please consult a PM&R specialist near you.
To make the most of the consultation, it helps to bring:
- A short timeline of your symptoms and what makes them better or worse
- A list of your medicines and other health conditions
- Previous imaging (the images themselves, not only the reports), test results and treatment summaries
- Your questions and goals, such as returning to work, sport or a particular activity
Frequently asked questions
Does hyaluronic acid rebuild cartilage? No. It is used for symptom relief.
What are the side effects? Temporary pain or swelling at the injection site; infection is rare. See Knee osteoarthritis treatment without surgery.
Is hyaluronic acid better than a corticosteroid injection? The evidence does not allow a clear general answer. Corticosteroid injections tend to act sooner and for shorter periods; hyaluronic acid effects, if any, tend to appear later. Neither is suitable for everyone.
How do I know if it is suitable for me? Suitability is decided by a physical medicine and rehabilitation specialist after examination, considering your symptoms, imaging, response to earlier treatments and the uncertain size of benefit.
Assessment and contact
You can request an appointment or a second-opinion review of existing reports and imaging: Contact & second opinion (WhatsApp). This page is general health information. Diagnosis and treatment decisions are made individually after examination.
Sources
- Rutjes AW, et al. Viscosupplementation for osteoarthritis of the knee: a systematic review and meta-analysis. Ann Intern Med. 2012. PMID: 22868835
- Bellamy N, et al. Viscosupplementation for the treatment of osteoarthritis of the knee. Cochrane Database Syst Rev. 2006. PMID: 16625635
- Bannuru RR, et al. OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis Cartilage. 2019. PMID: 31278997
- Kolasinski SL, et al. 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis Rheumatol. 2020. PMID: 31908163