Exercise for bone and cartilage in postmenopausal women with mild knee osteoarthritis

Abstract

The purpose of this study was to investigate the effects of high-impact exercise on bone mineral mass and strength, and on knee cartilage composition in postmenopausal women with mild knee osteoarthritis (OA). In addition, the association between knee OA and femoral neck bone structural characteristics in women with mild knee radiographic OA and those without radiographic knee OA was studied. Also, the reproducibility of measuring human knee joint cartilage by the delayed gadolinium-enhanced MRI (dGEMRIC) technique was determined in healthy asymptomatic subjects. Data from a 12-month randomized controlled trial (RCT) was used to assess the effects of exercise on bones and cartilages. The training intervention comprised 80 postmenopausal women with mild knee OA. The primary outcomes were bone mineral mass and strength, and the biochemical composition of knee cartilage as assessed by quantitative MRI measures: dGEMRIC and T2 relaxation time. Physical performance-related risk factors of falling were also evaluated. Data assembled from an additional sample of postmenopausal women with no knee symptoms (n = 12) and from the baseline measures of the postmenopausal women with mild knee OA were used in the cross-sectional association study. Prior to RCT, a test-retest study was conducted in healthy subjects (n = 10) to assess the reproducibility of dGEMRIC. The dGEMRIC technique showed good day-to-day reproducibility for the different knee cartilage regions. In the association study, femoral neck bone characteristics were significantly higher with higher grades in radiographic knee OA, indicating an inverse relationship between OA and osteoporosis (OP). The exercise program increased femoral neck bone mineral mass and strength. Exercise also had positive effects on physical performance-related risk factors for falls and exercise participation was well endured. However, the exercise had no effect on knee cartilage composition. To conclude, progressively implemented high-impact training is a safe and feasible exercise modality in the prevention of OP and physical performance–related risk factors for falls in postmenopausal women with mild knee OA.