Lower leg muscle mass relates to knee pain in patients with knee osteoarthritis.
OBJECTIVE
This study aimed to investigate the relationship between leg muscle mass measured by dual-energy X-ray absorptiometry (DEXA) and knee pain/stiffness in patients with radiographic knee osteoarthritis (OA).


METHODS
We performed a cross-sectional study using data from the Fifth Korean National Health and Nutrition Examination Survey. We included participants with radiographic knee OA (Kellgren-Lawrence grade ≥ 2) and obtained the degree of knee pain/stiffness and body composition of both legs and the whole body using DEXA. We calculated the ratios of legs to whole body in terms of muscle and fat mass. Analysis of covariance and multivariable logistic regression models were used to examine the associations of leg to whole body mass in patients with knee symptoms, adjusting for possible confounders.


RESULTS
We analyzed data for 1664 individuals. The ratio of leg to whole body muscle mass (LTWMM) was significantly lower in the group with knee pain or stiffness (30.27 ± 0.10 vs. 30.92 ± 0.08%, P < 0.0001). We found a significant inverse trend between the degree of knee pain and LTWMM (P for trend < 0.01). LTWMM was 14% lower in persons with severe pain (P = 0.012) when adjusted for age and sex. Leg to whole body fat mass was higher in the group with knee pain or stiffness (28.65 ± 0.22 vs. 27.95 ± 0.17%, P = 0.009).


CONCLUSIONS
DEXA-measured leg muscle mass was significantly associated with knee pain in people with radiographic knee OA. Low leg muscle mass is a useful clinical indicator for symptomatic knee OA, and DEXA is potentially an excellent tool to quickly assess leg mass in patients with knee OA.
Division of Rheumatology, Department of Medicine, Catholic University of Korea, Seoul, South Korea.
Ji Yeon
JY
Lee
Department of Biostatistics, Catholic University of Korea, Seoul, South Korea.
Kyungdo
K
Han
Division of Rheumatology, Department of Medicine, Tufts Medical Center, Boston, Massachusetts, USA.
Timothy E
TE
McAlindon
Department of Biostatistics, Catholic University of Korea, Seoul, South Korea.
Yong Gyu
YG
Park
Division of Rheumatology, Department of Medicine, Catholic University of Korea, Seoul, South Korea.
Sung-Hwan
SH
Park
D015502:Absorptiometry, Photon; D050154:Adiposity; D000368:Aged; D018771:Arthralgia / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007866:Leg; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000503:physiopathology; D009749:Nutrition Surveys; D016017:Odds Ratio; D020370:Osteoarthritis, Knee / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D010147:Pain Measurement; D011237:Predictive Value of Tests; D056910:Republic of Korea; D012307:Risk Factors; D012720:Severity of Illness Index
knee osteoarthritis; knee pain; knee stiffness; knee symptom; muscle mass; symptomatic knee osteoarthritis