Hyaluronic acid is a chemical found in many tissues of the body; you are probably familiar with its inclusion in many creams and pills touted for their beautifying qualities.  It was first isolated from cow’s eyes in 1934 and given the name “hyalos” based upon the Greek word for glass. Not knowing its purpose but recognizing its texture, entrepreneurs used it as an egg substitute in baking.  Further study revealed its importance in joint health and function.  

Hyaluronic acid serves as a lubricant to decrease friction between cartilage surfaces, transport nutrients to the cartilage, and keep free radicals and immune complexes from damaging joint linings.  In the early 1990s, physicians injected it into joints and saw improvements in both pain and function.  Because some formulations were isolated from rooster combs, it was jokingly called a “chicken shot.”  However, the gains in joint health were no laughing matter.

Benefits and Bummers

A large benefit of hyaluronic acid is that it is not damaging to cartilage like steroid; quite the contrary, in fact.  Although there is currently no treatment that can restore cartilage, hyaluronic acid is, at the very least, benign to cartilage while providing pain relief. It also does not have wide-ranging side effects like raising blood sugar levels or blood pressure, making it safer for many people with diabetes and hypertension.  Studies have shown the possibility of longer pain relief duration.  However, it appears a smaller percentage of people see improvements with hyaluronic acid than with steroid injection.

Potential side effects are the same as any joint injection: infection, bleeding, or damage to surrounding tissues.  There is also the rare possibility of what is called a “hyaluronic acid flare” in which a person experiences redness, heat, and swelling of the joint.  This is different from a joint infection in that a person is still able to bend his/her knee, whereas with infection, joint movement is very limited and painful.  There are also no body-wide signs of infection such as fever, chills, or elevations in white blood cell counts.  The flare represents a local reaction to the medicine and subsides after a couple days with Tylenol or ibuprofen, rest, and decreased weightbearing.  

Time to effect is slightly longer than steroid injections, taking about three weeks.  However, it also lasts longer, up to six months or more, and can be repeated indefinitely.  It is an excellent option for osteoarthritis pain, especially for those with lots of good cartilage left, who have failed steroids, or who have medical reasons for not using steroids or NSAIDs.  Currently, hyaluronic acid is only FDA-approved for use in the knee, so injections in other joints must be paid for out-of-pocket. 

Current Controversies

Hyaluronic acid has an interesting recent history.  Overall, treatments for knee arthritis pain have been somewhat disappointing, especially if a person does not respond to or can’t use steroid injections.  Hyaluronic acid provides an alternative that is safe, longer lasting, and benign to cartilage.  In 2021, the American Academy of Orthopedic Surgeons reviewed the available evidence on hyaluronic acid and released a Clinical Practice Guideline, a document presenting doctors’ opinions on a particular issue.  The Guideline did not recommend hyaluronic acid’s use, referencing a meta-analysis (a study that combines the results of many smaller, similar studies) that found hyaluronic acid to be no better than placebo.  Subsequently, many insurance companies stopped paying for it.

To put it simply, this made many musculoskeletal specialists very mad.  An important component of the therapeutic toolbox had been removed, and when you lack many big hammers, losing a trusty wrench felt like a big blow.  Many physicians identified with Mel Brooks’ newly-homeless millionaire Goddard Bolt in the movie Life Stinks, who opines after learning his slum is about to be demolished by a wealthy developer, “They force us to live in the crap, and now they want to take the crap away!”

Well, doctors wanted their crap back, so they pushed against the insurance companies.  To a certain extent, insurance companies relented, although many still require prior authorization before hyaluronic acid will be covered.  Thankfully, new guidelines allow hyaluronic acid as a second-line option.  If a conversation with a medical provider shows a person qualifies, hyaluronic acid is an outstanding choice for an injectable arthritis treatment.

References:

1. American Academy of Orthopaedic Surgeons Management of Osteoarthritis of the Knee (Non-Arthroplasty) Evidence-Based Clinical Practice Guideline. https://www.aaos.org/oak3cpg. Published 08/31/2021.
2. Trojian TH, Concoff AL, Joy SM, Hatzenbuehler JR, et al. AMSSM scientific statement concerning viscosupplementation injections for knee osteoarthritis: importance for individual patient outcomes. Clin J Sport Med. January 2016; 26(1): 1-11.
3. Moreira TD, Martins VB, da Silva AH Jr, Sayer C, et al. New insights into biomaterials for wound dressings and care: Challenges and trends. Progress in Organic Coatings. 2024; 187.