LAUSR

Abstract Objectives Intra-articular injection of hyaluronic acid (IAHA) has been used for the treatment of knee osteoarthritis (OA), but its effectiveness remains controversial. This study analyzed knee OA over time by magnetic resonance imaging (MRI) T1ρ mapping to objectively evaluate whether long-term repeated administration of IAHA influences cartilage degeneration. Methods Sixty knees of 60 patients [58.3 ± 12.5 years (mean ± standard deviation)] who had multiple T1ρ mapping images were retrospectively analyzed. We calculated the T1ρ values of the medial femorotibial cartilage and classified changes in degenerative areas over time into 3 groups: Improvement, No Change, and Deterioration. Results Average time between 2 MRI scans was 7.6 ± 1.2 months. The number of IAHA administrations was 15.5 ± 21.3, 8.39 ± 7.19, and 5.80 ± 7.49 in the Improvement, No Change, and Deterioration groups, respectively. Body mass index and number of IAHA administrations were significant factors causing change in the area of degeneration (p < .05) independent of age, sex, Kellgren–Lawrence grade, and posterior horn meniscus tears. Conclusion Cartilage degeneration may be improved with a higher number of administrations of IAHA, based on T1ρ mapping results. This highlights the possibility of increased treatment effectiveness of IAHA for knee OA with repeated administrations.