The Association between Radiographic Features and the Duration of Effectiveness of a Single Injection of Extended-Release Hyaluronic Acid (HANOX-M-XL) in Patients with Knee Osteoarthritis: Preliminary Results of a Prospective Trial

BACKGROUND: Advanced radiological stage of knee osteoarthritis (OA) is predictive of poor response to viscosupplementation (VS). To date, the impact of x-ray features on the duration of effectiveness (DE) of VS has not been investigated. OBJECTIVES: To investigate the radiological features associated with DE of VS in patients with knee OA. METHODS: Cross-sectional study in patients with knee OA treated with 1 injection of cross-linked hyaluronic acid (HA). The primary outcome was DE, self-assessed by the patients in weeks of effectiveness. Radiological features (joint space narrowing—JSN topography and Kellgren-Lawrence [K-L] grade) associated with DE were studied. RESULTS: Fifty-one patients—33 females (76 knees)—were analyzed. The average DE was 52.0 (24.7) weeks (range, 13-155 weeks). In the bivariate analysis, DE was 14 weeks longer in those with K-L grades 1 and 2 (62.6 ± 36.4 weeks) than in those with K-L 3 and 4 (48.9 ± 18.6) (P = 0.03). DE was not significantly different according to the involved compartment(s). It was significantly longer in men than in women (60 ± 31.4 vs. 47 ± 16 weeks; P = 0.035). In multivariate analysis, K-L grade (1-2 vs. 3-4) (P = 0.007), male gender (0.02), and older age (0.04) were independently associated with a longer DE. CONCLUSION: DE of a single injection of extended-release HA is longer in K-L 1-2 than in K-L 3-4 OA knees, regardless of the JSN topography. However, even the patients with more advanced OA benefited from HANOX-M-XL injection for an average duration barely less than 1 year.