Arthritis occurs when the cartilage of the joint wears away exposing bone. This bone exposure leads to pain, swelling and reduced function. Generally, simple treatments such as exercise, medications, and weight loss have the best effect on arthritis. However, in difficult cases, we use injections for arthritis in knees to help with these simple treatments. So, what are the options for knee joint injections and how do you decide?

Injections for arthritis in knees: What is available?

In general, we can use cortisone, hyaluronic acid, or platelet-rich plasma.


Cortisone is the most commonly used injection. We know that cortisone is a powerful anti-inflammatory drug that reduces inflammation, swelling, and pain.

Overall, studies show short-term improvement in knee pain after a cortisone injection.  Generally, the cortisone effect is better in milder knee arthritis cases and lasts up to 3 months. However, there is no difference between cortisone injections and placebo at 6 months for knee arthritis. Moreover, there are some concerns about cortisone injections for knee arthritis. For example, a recent study shows more cartilage wear after repeated cortisone injections. In addition, there is worrying evidence that having a cortisone injection could increase your risks of needing a joint replacement earlier. However, this evidence of needing a knee replacement earlier is not as strong. It is important we do more studies to assess whether repeated cortisone injections are harmful to joints.

Hyaluronic acid

hyaluronic acid injection

We also use hyaluronic acid (Ostenil, Durolane, Synvisc) in the treatment of osteoarthritis.

Hyaluronic acid is a natural substance found in bones, joints, and tendons. Injecting hyaluronic acid into a knee joint acts as a lubricator and reduces inflammation.

Overall, studies show a small effect on pain of osteoarthritis that can last for up to 6 months.  However, a particular type of hyaluronic acid that has a high molecular weight and high cross-link is more effective for knee arthritis. Particular brands that are high molecular weight include Duroalne and Synvisc-1. In addition, there are very few side effects apart from occasional allergic reactions.  All in all, hyaluronic acid is a reasonable option for mild to moderate knee arthritis.

Platelet-rich plasma


Platelet-rich plasma (PRP) is becoming more popular to treat arthritis and tendonitis.

We obtain PRP from whole blood. Then, we spin the blood to separate the plasma from red and white cells.  Plasma contains a high concentration of platelets that are rich in growth factors. Finally, the plasma is injected into joints.

Overall, there are 23 studies that show a good effect of PRP in knee osteoarthritis.  Furthermore, comparing PRP to other injections such as hyaluronic acid reveals a better effect from PRP. We discuss PRP injections further in this blog.

Stem cell

stem cell injections

Stem cell therapy is becoming more popular as a form of injection in arthritis. These stem cells have the ability to change to other cells and regenerate new tissue.

Usually, stem cells are derived from various sources including fat, bone marrow and fetal tissue. The process of taking and processing these cells can be difficult and expensive. So, is the hassle and cost worth it?

Generally, the answer is no. While some smaller low-level studies show promise, higher-level studies show no difference between stem cells and cheap sterile water. Overall, we don’t recommend you waste your money (up to £7000) on stem cells until further evidence becomes available of effectiveness.

Final word from Sportdoctorlondon

Overall, we use intra-articular injections for arthritis when other simple treatments such as exercise and weight loss are not good enough.  Generally, use cortisone for an angry swollen knee. Hyaluronic acid or Platelet-rich plasma is our second choice with a preference for Platelet-rich plasma.  Finally, you should always perform injections with ultrasound to make it more accurate. If you’re thinking about an injection, you should do your homework and find a doctor with experience in ultrasound and injections.

Other knee conditions:

Dr. Masci is a specialist sport doctor in London. 

He specialises in muscle, tendon and joint injuries.

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