Knee extensor strength does not protect against incident knee symptoms at 30 months in the multicenter knee osteoarthritis (MOST) cohort.
OBJECTIVE
Knee extensor weakness has not been associated consistently with the risk for incident knee pain. Additionally, the balance of hamstring-to-quadriceps strength (H:Q ratio) may affect risk and has not been studied. The authors determined whether knee extensor weakness or muscle imbalance is a risk factor for development of frequent knee pain or stiffness and whether the effect is modified by lower limb alignment.


METHODS
Observational study.


METHODS
Community.


METHODS
Community-dwelling adults ages 50-79 years with or at risk of knee osteoarthritis based on obesity, knee injury, or surgery. A total of 1269 knees from women and 1006 knees from men without frequent knee symptoms at baseline and with 15- or 30- month follow-up outcome data were included.


METHODS
Isokinetic knee extensor and flexor strength as well as radiographic hip-knee-ankle alignment were measured at baseline. H:Q ratio was dichotomized, with normal being considered to be >/=0.6.


METHODS
Frequent knee symptoms at 15- or 30-month follow-up (frequent knee pain, aching, or stiffness on most days of the past month reported at both telephone contact just before and at visit).


RESULTS
Mean +/- SD age was 62.2 +/- 8.0 years and mean body mass index (BMI) was 30.1 +/- 5.4 kg/m(2). Mean peak knee extensor strength (KES) was 132.6 +/- 42.4 and 76.9 +/- 25.3 N.m in men and women, respectively. Approximately 50% of knees in men and 59% of knees in women had an H:Q ratio <0.6. A total of 307 of 2275 eligible knees developed frequent knee symptoms at follow-up. Logistic regression controlling for age, BMI, femoral neck bone mineral density, activity score, and baseline Kellgren Lawrence grade revealed that neither KES nor H:Q ratio predicted the development of knee symptoms in gender-stratified or combined analyses. These results were unaffected by adjusting for lower limb alignment.


CONCLUSIONS
Neither concentric quadriceps strength nor H:Q ratios predicted the development of frequent knee symptoms at 15- or 30-month follow-up in this cohort.
Segal
Neil A
NA
Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive, 0728 JPP, Iowa City, IA 52242-1088, USA. segal-research@uiowa.edu
Torner
James C
JC
Felson
David T
DT
Niu
Jingbo
J
Sharma
Leena
L
Lewis
Cora E
CE
Nevitt
Michael
M
D000368:Aged; D018771:Arthralgia / Q000453:epidemiology*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000150:complications* / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology; D052097:Quadriceps Muscle / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology