Injections for Knee Pain

By Barbara Hales, M.D.
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Injections for Knee Pain

Overview of injections for knee pain

Osteoarthritis is a type of arthritis distressing the knees with a breakdown of cartilage (the covering that protects joint bones). The bone surface starts eroding and becomes damaged causing swelling, stiffness and pain.

When knee pain becomes a chronic problem typically due to osteoarthritis, and unresolved with oral medications, injections may bring relief of pain and inflammation.

What can I expect with Injections for knee pain?

After local anesthesia is inserted to numb the knee, a needle aspirates excess fluid in the joint. An injection with medication for pain-relief is then injected into the joint, just below the kneecap.

There are 4 types of injections for knee pain:

  1. Corticosteroid injections – Injections of corticosteroids are injected directly into the knee joint to provide pain relief and a decrease of inflammation. Benefits may be observed up to 6 month and can be seen as quickly as 24-48 hours. Unfortunately, repeated injections can lead to cartilage breakdown over time.
  2. Arthrocentesis – Also known as joint fluid aspiration, this procedure is withdrawal of excess fluid through a needle inserted into the joint space, immediately reducing swelling and giving pain relief. Using the same puncture site, corticosteroid solutions or anesthetics may be injected into the knee joint to further enhance pain relief.
  3. Hyaluronic acid supplements – These supplements are injected into the knee joint weekly for 3-5 times after some joint fluid withdrawal to augment hyaluronic acid which is naturally present. The hyaluronic acid works as a lubricant and shock absorber but is deteriorated when suffering from osteoarthritis.
  4. Platelet-Rich Plasma (PRP) – A sample of blood is drawn and a fluid is created with a higher concentration of platelets to help clot blood. This is then injected into the joint space. Platelets hasten healing and tendon damage repair has been seen with PRP usage. Studies are ongoing for effectiveness in osteoarthritis repair.

Do injections for knee pain work?

Injections for knee pain have been successful in relief of pain and inflammation. The benefit of lubrication and cushioning the bones is only temporary though.

What should I know about injections for knee pain

You may need as many as five injections during a five-week span. If still unsuccessful, it may be repeated after 6 months. Risk of cartilage breakdown may ensure however.


Bruce Arroll, associate professor, “Corticosteroid injections for osteoarthritis of the knee: meta-analysis” BMJ 2004; 328:869, published 08 April 2004
John Richmond, MD, chairman of orthopedic surgery, New England Baptist Hospital, professor of orthopedic surgery, Tufts University School of Medicine, Boston.
CDC: “Osteoarthritis.”
American College of Rheumatology: “Osteoarthritis.”
Rutjes, A. Annals of Internal Medicine, August 7, 2012.
Bellamy, N. Cochrane Database of Systemic Reviews, April 19, 2006.
Axe, J. Sports Medicine and Arthroscopy Review, March 2013.
Smelter, E. Current Opinion in Rheumatology, February 16, 2013.
American Academy of Orthopaedic Surgeons: “Platelet-rich plasma (PRP).”