A meta-analysis of treatments for osteoarthritis of the knee reached a surprising conclusion: intra-articular injections were more effective in relieving pain than any oral medication. (Annals of Internal Medicine, January 6, 2015, pages 46-54)
The knee is the joint most commonly affected by osteoarthritis. Forty percent of people older than 45 years have some degree of knee osteoarthritis. Four hundred thousand knee replacements occur every year in the US. Millions have pain and stiffness that limits their ability to exercise, leading to obesity and all the complications associated with it, including worsening arthritis.
Usual treatments include oral medications: acetaminophen, and NSAIDs, like ibuprofen, naproxen, celecoxib and diclofenac. These medications can be expensive, costing up to $3000 a year, and have dangerous side effects, especially in older people who are most likely to have knee problems. NSAIDs cause fluid retention, high blood pressure, congestive heart failure, stomach ulcers and gastrointestinal bleeding, liver and kidney damage.
Knee injections of various types, including hyaluronic acid and steroids, were better than oral medications. In fact, injections of placebo, such as water, worked as well as oral medications. Injected placebo worked better than oral placebo. There appears to be an intra-articular physiologic effect, simply through the injection of fluid into a joint, that modifies the perception of pain, and may modify inflammation as well.
This idea, that the injection process itself is effective, would fit into the finding that epidural injections of lidocaine for low back pain are as effective as injections of steroids.
Injections themselves have very low risk, much lower than the risk of oral medications.
We are using prolotherapy and ozone injections as first line treatments for knee pain, and also platelet-rich plasma (PRP) injections. Response rates have been in the range of 80-90%, and sometimes pain has gone away completely. Injections can be repeated after 2-3 weeks if needed.
Allan Sosin, MD