They seem to help with knee pain, but only to a limited extent, for a limited time and in certain patients.
Injections can delay knee replacement surgery for as long as a year or two, said Dr. Donald T. Reilly [cq], an attending orthopedic surgeon at New England Baptist Hospital. That’s a decided advantage since artificial knees, like real ones, eventually wear out, he said.
And the injections, “seem to help” if osteoarthritis caused by wear and tear on a joint isn’t too severe. (They’re not designed for rheumatoid arthritis.)
But “the science behind this is not great,” Reilly said. “The actual mechanism of the supplements is not clear.” The injections seem to boost one of the constituents of synovial fluid, hyaluronic acid, but not other components.
The medications, with names like Synvisc, Orthovisc and Hylan G-F20, are supposed to supplement the thick or viscous synovial fluid found in normal knees for lubrication and cartilage nourishment. They can cost several hundred dollars for a series of three or more injections and may not be covered by insurance.
Overall, the benefits appear to be modest, said Dr. Paul Romain [cq], chief of rheumatology at the Cambridge Health Alliance. But the injections are worth asking about, he said, if you are unable to have surgery.