Standardized Follow-up of Patients with Symptomatic Knee Osteoarthritis Treated with a Single Intra-articular Injection of a Combination of Cross-Linked Hyaluronic Acid and Mannitol

OBJECTIVES: The objective of this study is to obtain pilot data from daily practice conditions of a viscosupplement made of a cross-linked high-molecular-weight hyaluronic acid (HA) combined with mannitol in patients with knee osteoarthritis (KOA). METHODS: The data of 40 consecutive patients, 29 women and 11 men, who were prospectively followed up for 6 months, using a standardized procedure, were retrospectively analyzed. All patients have received a single intra-articular injection of HAnox-M-XL (4.4 mL), viscosupplement made of a cross-linked HA (16 mg/mL) + mannitol (35 mg/mL), in the target knee. The primary outcome was safety. The secondary end points included 3- and 6-month change in the WOMAC pain (0–50) and WOMAC total (0–240) and patient’s global assessment (PGA). Patient’s self-assessment of treatment efficacy (0–3) and analgesic consumption were obtained at months 3 and 6. An intent-to-treat analysis was performed. RESULTS: Mean (SD) age was 60.7 (13.9) years, and mean BMI was 28.6 (5.0). Kellgren–Lawrence radiological grade was I/II and III/IV in 13 and 27 of the subjects, respectively. The average WOMAC pain and WOMAC total scores at baseline were 21.5 (9.8) and 89.9 (42.8), respectively. Thirty-nine patients completed the follow-up. HAnox-M-XL was well tolerated; two patients experienced knee pain after injection, which resolved within three days. No treatment-related severe adverse event was reported. Mean (SD) variations in WOMAC pain and WOMAC total scores were −8.2 (8.9) and −38.4 (35.6), respectively, at month 6 (P = 0.001). PGA decreased from 5.5 (2.0) to 3.0 (2.2) (P = 0.006). Efficacy was rated as good or very good in 76.9% of the cases. Most of the regular analgesics users decreased their consumption. CONCLUSION: Treatment with one injection of 4.4 mL HAnox-M-XL is effective to alleviate KOA symptoms over six months, without safety concern. Controlled trials are needed to confirm these pilot data.