How well do hyaluronic acid joint injections work? The answer isn't clear. Many studies have sought to answer the question and come up with different results.
For instance, one study published in Rheumatology found that in the short term, hyaluronan was no better at reducing joint pain than a placebo injection of salt water. An analysis of seven different studies published in the Journal of Family Practice did not recommend the treatment in its conclusion, since the benefits - if it had any at all - were so slight.
But a similar analysis of twenty studies - published in The Journal of Bone and Joint Surgery -- found that injections of hyaluronan did reduce pain and increase the function of the knee in people with osteoarthritis.
In studies that show effectiveness, pain relief lasts up to six months or a year. It works better in some people than in others. People who are older or have advanced osteoarthritis may be less likely to be helped.