Published: Oct 31, 2013
By Nancy Walsh, Staff Writer, MedPage Today

Full Story:  http://www.medpagetoday.com/MeetingCoverage/ACR/42626

SAN DIEGO — Patients with knee osteoarthritis who were given injections of hyaluronic acid were able to delay undergoing total knee replacement, a researcher said here.

Overall, among patients who had total knee replacement because of severe osteoarthritis, those who had received hyaluronic acid injections had the surgery up to 2.6 years later than those who didn’t have the injections, Roy D. Altman, MD, of the University of California Los Angeles, reported in a poster session at the annual meeting of the American College of Rheumatology.

“It’s important to delay total knee replacement as much as possible, particularly in younger patients, because it isn’t a cure-all and the joint survival is only about 9 to 10 years before they have to have revision surgery,” he told MedPage Today.

More than 27 million U.S. adults currently have knee osteoarthritis, and they use various medical and physical strategies to alleviate pain and improve function.

Among patients with persistent pain and impairments, hyaluronic acid injections can help restore intra-articular synovial fluid function and improve clinical outcomes, but the impact on the need for joint replacement hasn’t previously been quantified.

“The decision to have total knee replacement is complicated, and can be influenced by disease severity, patient expectations, and insurance coverage,” Altman said.

So he and his colleagues analyzed data from a commercial database that included more than 7 million individuals enrolled between January 2007 and December 2011.

Of the 26,627 patients in this database who had been diagnosed with osteoarthritis and had total knee replacement, 7,000 had received at least one injection of hyaluronic acid.

From the group of 19,627 patients without injections, 6,891 were chosen as propensity-score matched controls.

Two-thirds were women, and most were in the 55-to-59-year age group.

A total of 79% had undergone a single injection, 16% had two, 4% had three, and 1% had four or more; there was a clear dose-response. The median number of days until total knee replacement after an initial visit to a specialist according to number of injections were:

• One, 162 (95% CI 151-172)
• Two, 343 (95% CI 328-355)
• Three, 584 (95% CI 564-613)
• Four, 740 (95% CI 656-838)
• More than four, 975 (95% CI 781-1,072)

An additional reason to put off this surgery as long as possible is that almost one-third of patients continue to have difficulties, including pain, after the joint replacement, Altman pointed out.

Limitations of the study included its reliance on administrative data, which didn’t include factors that could influence joint replacement such as practice patterns, and varying lengths of follow-up among patients.

In addition, although the researchers attempted to control for osteoarthritis severity by using propensity scores, other differences might exist between patients who did and didn’t receive hyaluronic acid injections.