A new study published by R Altman et al. shows that Hyaluronic Acid (HA) injections delayed Total Knee Replacements (TKR) by a significant amount of time. "Those receiving HA injections had a median 1.6-year longer Time-to-TKR surgery versus those who did not receive HA injections. These results have both clinical and economic implications."

http://www.ncbi.nlm.nih.gov/pubmed/26641076