THE RELATIONSHIP OF THIGH MUSCLE COMPOSITION AND FAT WITH MUSCLE POWER AND PHYSICAL FUNCTION IN WOMEN WITH KNEE OSTEOARTHRITIS

Abstract

The aim of this study was to investigate the relationship between thigh intramuscular fat (intraMF) and intermuscular fat (IMF) with quadriceps and hamstrings power and physical performance in women (n=20) with clinical, radiographic knee osteoarthritis (OA). Secondarily, we investigated the correlation between thigh and calf fat volumes, and the agreement between 3.0T and 1.0T MRI for quantifying fat. The thigh and calf of the symptomatic leg were scanned using 3.0T MRI with the IDEAL sequence, and fat separated images were analyzed using semi-automated software to quantify intraMF, IMF and muscle. The calf was also scanned using 1.0T MRI with a Fast Spin Echo (FSE) sequence. Knee extensor and flexor isokinetic power was measured at 20% and 40% of individuals’ maximum voluntary isometric contraction (MVIC) torque, and surface electromyography (EMG) measured activation. We found no relationship between quadriceps or hamstrings intraMF and knee extensor or flexor power, respectively. In addition, there were no relationships between intraMF and performance-based tests. There was a correlation between thigh and calf intraMF (r=0.759; p=0.001) and a trend toward a correlation in IMF (r=0.436; p=0.055). There was agreement and a correlation between calf intraMF (r=0.779; p=0.001) and IMF (r=0.956; p=0.001) using 3.0T and 1.0T MRI. There is disagreement about the relationship of intraMF and quadriceps strength, although studies have found that intraMF is related to decreased physical performance. The importance of calf fat subsets in physical performance of individuals with OA should be further investigated. Power analysis demonstrated a sample size (n=91) is recommended for future investigations of intraMF and power in OA.