When are therapeutic injections recommended to treat knee arthritis pain? It depends on several factors, such as treatment goals and what is causing the knee pain.

Cortisone, hyaluronic acid, platelet rich plasma (PRP), and stem cell injections, as well as prolotherapy can all be used to treat knee osteoarthritis. Read Therapeutic Injections for Knee Arthritis

This page discusses when a patient might be advised to consider a therapeutic injection, such as a cortisone, hyaluronic acid, or platelet rich plasma (PRP) injection.


Seeking Fast, Temporary Relief from Knee Osteoarthritis

People may want temporary relief from knee osteoarthritis pain so they can postpone knee replacement surgery or pursue other treatments. Examples of treatments include participating in physical therapy to strengthen muscles around the joint or dieting to assist with weight loss, which relieves pressure on the joint. Other people may seek temporary relief so they can participate in a particular activity, such as a vacation that involves lots of walking or hiking.

See Knee Osteoarthritis Treatment

Cortisone and hyaluronic injections are commonly used for fast, temporary relief from knee osteoarthritis pain.

Cortisone injections may begin working within 24 hours of the injection, and the effects of a cortisone injection typically last between 6 weeks to 6 months. The goal of a cortisone injection is to reduce inflammation, which is often the underlying cause of pain.

See Cortisone Injections (Steroid Injections)

Hyaluronic acid (viscosupplementation) injections tend to work more slowly than cortisone—the full effects may not be felt for about 2 weeks—but the effects may last longer. The primary goal of a hyaluronic acid injection is to lubricate the knee joint. This treatment is not always covered by insurance.

See Hyaluronic Acid Injections for Knee Osteoarthritis

Some people who get cortisone injections experience a painful “cortisone flare.” A flare may last a couple of hours or a couple of days after the injection. Experiencing a cortisone flare does not mean that the cortisone injection will not work.

See Cortisone Injection Risks and Side Effects

In addition, some experts have raised concerns that cortisone may cause long term joint tissue damage 1 Nuelle CW, Cook CR, Stoker AM, Cook JL, Sherman SL. In Vivo Toxicity of Local Anesthetics and Corticosteroids on Supraspinatus Tenocyte Cell Viability and Metabolism. Iowa Orthop J. 2018;38:107-112. PubMed PMID: 30104932; PubMed Central PMCID: PMC6047373. , 2 Sherman SL, James C, Stoker AM, Cook CR, Khazai RS, Flood DL, Cook JL. In Vivo Toxicity of Local Anesthetics and Corticosteroids on Chondrocyte and Synoviocyte Viability and Metabolism. Cartilage. 2015 Apr;6(2):106-12. doi: 10.1177/1947603515571001. PubMed PMID: 26069713; PubMed Central PMCID: PMC4462250. , 3 Piper SL, Kramer JD, Kim HT, Feeley BT. Effects of local anesthetics on articular cartilage. Am J Sports Med. 2011 Oct;39(10):2245-53. doi: 10.1177/0363546511402780. Epub 2011 Apr 22. Review. PubMed PMID: 21515808. —particularly if multiple injections are done at the same joint.

See What to Know Before Getting a Cortisone Injection

Not all people who get cortisone or hyaluronic injections experience a decrease in knee pain.

Stopping an Arthritis Flare

Significant knee pain, swelling, redness, and tenderness can be caused by an arthritis flare. Arthritis flares are associated with autoimmune forms of arthritis, such as rheumatoid arthritis and gout.

See Inflammatory Arthritis

A cortisone injection may be recommended to stop the inflammation of an arthritis flare. Cortisone is a powerful anti-inflammatory.

See What Is Cortisone?

An inflammatory flare in the knee joint results in excess fluid in the knee’s joint capsule. A physician can use a hand-held ultrasound probe to verify there is excess fluid in the knee. This fluid can be drained before the cortisone injection. Using ultrasound also allows the doctor to see the exact location of the needle within the joint and precisely place the cortisone injection. Ultrasound imaging is painless.

See Cortisone Injection Procedure


Trying to Prevent the Progression of Knee Osteoarthritis

Knee osteoarthritis is defined by the loss of articular cartilage in the knee joint. Articular cartilage does not heal easily, so the damage and loss of cartilage are often progressive and permanent. However, some researchers believe injections that use regenerative medicine can stop the progression of osteoarthritis and even spur healing.

These regenerative medicine injections include:

Platelet rich plasma injections (PRP). PRP therapy attempts to take advantage of the blood's natural healing properties to repair damaged joint tissue, including cartilage tissue. It is derived from a sample of the patient's own blood. PRP is extremely safe as the platelets are naturally occurring within your body and the activated concentrated platelets bring growth factors and anti-inflammatory agents into the injected region of concern especially when injected under ultrasound guidance.

See Platelet-Rich Plasma (PRP) Therapy for Arthritis

Stem cell injections. Researchers theorize that, when injected into an osteoarthritic knee, stem cells can signal the body’s own reparative process; suppress inflammation; slow down cartilage degeneration; and/or decrease knee pain.

See Stem Cell Therapy for Arthritis

Prolotherapy. Prolotherapy involves several injections—15 or 20—during one treatment session. During treatment, a physician will inject an irritant, such as a dextrose solution, into the arthritic knee joint and surrounding tissues. Limited research suggests this process may stimulate natural tissue repair in the body.

Many clinical research studies suggest that PRP, stem cell injections, and prolotherapy are effective in treating knee osteoarthritis. However, those clinical studies currently vary in quality. Well-designed randomized controlled studies are in progress to standardize the regenerative medicine treatment process.

See Therapeutic Injections for Knee Arthritis

Regenerative medicine treatments are not considered standard for treating osteoarthritis. Currently, they are widely available and offered by physicians with varying credentials. Read more about choosing regenerative medicine treatments, including a list of questions to ask a physician.

Read more about Whether to Choose Regenerative Medicine Treatment on Sports-health.com

Dr. Michael Antonis is a physician specializing in non-operative general orthopedics and sports medicine. For more than a decade, Dr. Antonis served as an emergency physician, holding positions as Associate Chief of Service at MedStar Georgetown University Hospital and Chair of Emergency Services at MedStar Southern Maryland Hospital Center.