Exercise as stimulus for cartilage health in knee osteoarthritis

Abstract

Knee osteoarthritis (OA) is a leading cause of musculoskeletal pain and disability and has significant socio-economical costs globally. There is no known cure for OA. Therapeutic exercise has been shown to evoke acute positive posttreatment effects on pain and function. Even though cartilage degeneration is crucial in OA progression, there is sparse knowledge about exercise effects on osteoarthritic cartilage. The purpose of this study was to investigate the efficacy of aquatic resistance training on the estimated biochemical composition of tibiofemoral cartilage and the association between leisure time physical activity (LTPA) and tibiofemoral cartilage in postmenopausal women with mild knee OA. This study utilizes data from a large randomized controlled trial (RCT) intervention project, AquaRehab (ISRCTN65346593). In 4-month progressive aquatic resistance training (RCT) and in 12-month LTPA follow-up studies, the biochemical composition of the knee cartilage was evaluated using T2 relaxation time and dGEMRIC index quantitative MRI methods in 87 postmenopausal women with mild knee OA. Cardiovascular fitness, muscle force, symptoms, quality of life and self-assessed function were also measured. Additional data from our previous RCT intervention project, LuRu (ISRCTN58314639), was utilized in a cross-sectional study assessing the association between neuromuscular performance and lower limb bone strength in 139 postmenopausal women with mild knee OA. The 4-month progressive aquatic resistance training resulted in positive regional changes in mildly osteoarthritic knee cartilage and improved cardi- orespiratory fitness. Also, there was a significant decrease in self-assessed stiffness in the training group compared to controls. In addition, higher LTPA level was related to regional improvements in knee cartilage quality during a 12-month follow-up period. Further, neuromuscular performance predicted lower limb bone strength in every measured skeletal site in women with knee OA. In conclusion, continuously implemented physical activities may result in regional adaptation in mildly osteoarthritic knee cartilage and a positive effect on cardiorespiratory fitness and self-assessed knee stiffness.