The effect of viscosupplementation on early-stage knee osteoarthritis: Clinical evaluation and assessment of cartilage in vivo with 7 T MRI

Introduction: Viscosupplementation is a well-known strategy for managing early stages knee Osteoarthritis. However, despite its effectiveness in reducing symptoms, it has not yet been found to have an effect on joint cartilage. The aim of this study is to evaluate the clinical efficacy of a new product with gel-like behaviour and its in vivo effects on joint cartilage. Methods: 20 patients were treated by 2 consecutive injections of hyaluronan derivative Hymovis® at one-week interval. Clinical evaluation was performed before the treatment and at each time point during the follow-up using WOMAC and VAS. A 7 T magnet was used for cartilage evaluation at each MRI time point: T2 Relaxation Time (RT), T2∗ RT and cartilage parameters were evaluated before the first injection, after 45 days and at 6 months follow-up. Statistical analysis was obtained for each reported data. Results: We report significantly reduction in symptoms with an increase in knee and global activity functions. The T2 RT for lateral tibial compartment and T2∗ RT for Patello-Femoral compartment significantly decreased. A T2 RT reduction was observed in all knee compartments except for the medial tibial one, while a T2∗ RT reduction was observed in all knee compartments. We report an increase in cartilage volume and thickness in most of patients with a reduction of cartilage defects in 9 patients, but we didn't find MRI signals clearly referable to cartilage regeneration. Conclusions: MRI results have confirmed the possibility to employ 7T magnets to evaluate early changes in cartilage structure in vivo. HA VS has provided good clinical outcomes and an improvement in the global assessment of the knee joint, but it doesn't seem to significantly modify the cartilage over the time.