LONG-TERM SUSTAINED BENEFITS OF VISCOSUPPLEMENTATION WITH DIFFERENT MOLECULAR WEIGHT INTRA-ARTICULAR HYALURONIC ACIDS IN THE TREATMENT OF OSTEOARTHRITIS OF THE KNEE - HAV-OAK - A RETROSPECTIVE INDIAN COHORT STUDY OF MORE THAN 15 YEARS

Knee osteoarthritis (OA) is a progressive degenerative condition resulting in functional loss, pain, and discomfort.[1] Viscosupplementation (VS) with Intra-articular hyaluronic acid (IAHA) injections has been shown to have protective physiochemical functions and may confer disease-modifying, long-term effects in OA. [2][3] However, conflicting guidelines, pooling of results for different molecular weight (MW) products, and a paucity of long-term clinical studies have resulted in a lack of confidence in the results of IAHA. The primary objective of the study was to determine the long-term sustained effects of VS with different MW of IAHA in Knee OA in maintaining functional improvement. The secondary objective was to determine the required interval between follow-up injections with different MW of IAHA. We performed a retrospective analysis of a 15-year cohort from a single centre (India). The inclusion criteria were adults with bilateral knee OA with functional reduction and radiological KL Grade III & IV, treated with Non-Animal Derived IAHA. Subjects were stratified into two groups based on the MW of the hyaluronic acid used: High MW - 6-8 mg/ml – 6ml (HMW-HA), or Very high MW – 20 mg/ml – 3 ml (VHMW-HA). The primary outcome measure was responder rates with improvement in WOMAC scores of > 30% from baseline versus non-responders. Those with a response lasting > 6 months after each injection were considered as sustained responders. A total of 2037 (female (F) 1467, and male (M) 570 patients were treated. The total primary responders were 1496 (73.44%) with 1099 F, and 397 M. Compared to HMW-HA, VHMW-HA had significantly higher primary responders (75.21% vs. 70.22%, p=0.015) and significantly lower non-responders (24.79% vs. 29.78%, p=0.015). The sustained responders were 1186 (79.28%) of the primary responders. The sustained response was significantly greater with VHMW-HA vs. HMW-HA (85.54% vs.67.06% p-value < 0 .0001) The average interval between the first and the third injections was significantly larger for VHMW-HA vs. HMW-HA - 5.67 (Median 25th-75th percentile – 5.392 - 6.036) vs. 1.95 (Median 25th-75th percentile – 1.753 - 2.24) years. P-value < 0 .0001. Primary responders rate of 73.44% justify treatment with IAHA. The sustained response with VHMW-HA was > HMW-HA. VHMW-HA has a longer duration than HMW-HA.