Hyluaronic Acid Injections
When the joint becomes osteoarthritis the natural joint fluid decreases and becomes less viscous. Joint fluid is comprised of hyaluronic acid. Synovial or joint fluid depends on Hyaluronic acid for its viscoelasticity. This keeps the joint lubricated and protects the joint. We can augment this diminished joint fluid with hyaluronic acid injections. This diminishes the pain and disability of the osteoarthritic joint. There is now even a theory that these injections may slow the progress of the degradation of the joint by the arthritis.
CHEMICAL MAKE UP
While most of the formulations on the market are derived from Rooster Coombs some like Orthovisc/Monovisc are now made synthetically in the lab
SINGLE VS. MULTIPLE INJECTIONS
Traditionally most injections were given once a week for three weeks (Orthovisc). This has worked very well. There are now preparations where the amount of hyaluronic acid is concentrated into one larger injection (Monovisc) and given in a single dose. Your doctor will help you decide which is better for you.
DO THE INJECTIONS HURT
Your physician may or may not use freezing before they inject the hyaluronic acid into the knee. Even without freezing there is minimal pain from the injection. Your knee may ache for a few days after the injection but even then this is rarely the case.
HOW DOES IT WORK AND FOR HOW LONG
We know that the main component of the synovial (joint) fluid is Hyaluronic Acid. The joint fluid which is crucial in maintaining the lubrication and protection of the joint is diminished in the osteoarthritic joint. The injections work to restore the some of the Hyaluronic Acid in the joint and help to restore the lubrication and protection of the joint surfaces. It is unclear why the effect lasts for so long after the injections but suffice to say we know form clinical studies and from our clinical impression that the injections give relief from 6-12 months. The process is then repeated.
Hyaluronic acid is an inert substance which naturally occurs in the joint. Therefore as far as we know there are no systemic side effects from the injections. There is always a potential risk of an infection from the injection itself as you break the skin to put a needle into the knee but under sterile technique this is extremely rare. Occasionally your knee may ache or swell slightly for several days after the injection
WHEN DO THE INJECTIONS START TO WORK
With the three injection Orthovisc preparation many but certainly not all will start to feel a difference after the second injection. Generally it will be a few weeks after the third injection or after a single Monovisc injection that you will gradually start to feel a difference.
CARE AFTER THE INJECTION
You will walk out of the office following the injection and immediately resume normal daily activities. If there is any pain Tylenol (acetaminophen) may be used. If there is any swelling or aching an ice pack can be applied for 20 minutes every couple of hours.
RETURN TO SPORTS
It is recommended that you refrain from any sports activity for 24-48 hours after the injection.