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Osteoarthritis is the most common type of arthritis and the knee is the most common joint affected. Unlike rheumatoid arthritis, which is an inflammatory disease, osteoarthritis is due to the wear and tear of time. The bones of your knee joint are covered with a tough and smooth protective layer of cartilage and the joint is filled with a lubricating fluid. That allows your knee to move while you walk and run without damaging the ends of the bones.
By age 70, for about 40 percent of people, the knee joint cartilage has started to thin or wear away. Bones are grinding on bones, the joint space gets narrower, and symptoms of pain and stiffness start to be a problem. There is no cure for osteoarthritis and it tends to gets worse over time, but there are some effective treatments. For about 10 percent of people with knee osteoarthritis, knee injections are part of the treatment.
American Academy of Orthopedic Surgeons (AAOS) Treatment Guidelines
According to the AAOS, the first treatments for osteoarthritis should include physical therapy and home exercise, nonsteroidal anti-inflammatory drugs (NSAIDs), weight loss if needed, and low-impact aerobic exercise. These treatments are called non-invasive treatments because they do not involve any injections or surgery. They can be managed with your primary care doctor. Non-invasive treatments can’t reverse damage done by osteoarthritis or prevent damage from getting worse, but they can slow down the disease and relieve symptoms. For many people, this is enough to make the disease manageable.
NSAIDs can include both over-the-counter medications like Advil or Motrin, and prescription strength NSAIDs from your doctor. Physical therapy may include exercise, heat or cold applications, as well as massage or low-voltage transcutaneous electrical nerve stimulation (TENS) to reduce pain. Low-impact exercises reduce joint stress and can include swimming or walking.
There is not much evidence to support alternative treatments. Some studies suggest a role for acupuncture to reduce pain. There is less support for joint supplements like glucosamine and chondroitin. Although many people seem to get relief, studies suggest this is probably a placebo effect. Omega-3 fatty acids in fatty fish or fish oil supplements have better evidence than other supplements for relief of pain and improving function.
The Role of Knee Injections
Knee injections are invasive therapies, usually given by an orthopedic specialist. According to two 2022 studies presented at the annual meeting of Radiological Society of North America; people who had steroid knee injections had more progression of osteoarthritis on knee imaging studies than people who had no injections. Steroid knee injections were also associated with more progression than knee injections using a substance called hyaluronic acid. Steroids work by decreasing swelling in the knee, so they do relieve pain and improve movement. Hyaluronic acid is a lubricant that may help protect the remaining cartilage in the joint.
These new studies do not prove that steroid injections make knee osteoarthritis worse, and they are not the first studies to suggest that steroids may be linked to worse long-term outcomes. It may be that the patients who get steroid injections just have worse arthritis. According to AAOS guidelines, steroid injections are reserved for people who have significant changes on their knee x-rays, severe pain, and have not responded to non-invasive treatments.
AAOS guidelines say steroids should be used for severe pain and inflammation because most studies show that these injections reliably relieve pain and swelling. AAOS does not recommend hyaluronic acid as a first treatment for severe osteoarthritis because the research does not support it. AAOS also says steroid injections should be limited to three or four times per year to reduce the risk of worsening joint damage over time.
The Role of Knee Surgery
Knee replacement surgery is recommended when all other treatments are not helping. Advances in knee replacement surgery have made it one of the fastest growing surgical options, even in people under age 60. The main reason is that replacing the knee with a meatal and plastic joint takes the pain away and returns basic function. In the hands of an experienced orthopedic surgeon, these results benefits are very reliable, and can last from 15 to 25 years.