Differential muscle strength decline in osteoarthritis of the knee. A developing hypothesis.
The ratio of quadriceps to hamstrings muscle strength (Q/H ratio) is important for the stability of the knee and for protection from excessive stress. The purpose of this study was to explore whether the Q/H ratio is altered in patients with osteoarthritis (OA). Subjects were 43 patients with physician-diagnosed OA of the knee (mean age, 65.61 years; SD, 12.74). Isometric knee flexor and extensor strength was measured with a hand-held dynamometer. Both muscle groups were weak, with relatively greater weakness in the quadriceps muscles. The mean Q/H ratio of 1.43 (SD, 0.39) was below ratios reported for young healthy adults (2.0). The low Q/H ratio might be caused by the inability to correct the measurement for gravity, but a liberal estimate of gravity correction raised the ratio only to 1.71 (SD, 0.47). The low Q/H ratio was probably not caused by physiologic changes due to aging, because the correlation between the ratio and age was low (-0.04). Since the correlation of the Q/H ratio with the usual level of pain (measured by a visual analogue scale) was negative (-0.26), the low ratio might be explained by reflex inhibition due to pain associated with disease.
Hayes
K W
KW
Falconer
J
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D007719:Knee Joint; D008875:Middle Aged; D009129:Muscle Tonus; D010003:Osteoarthritis / Q000150:complications* / Q000503:physiopathology; D016059:Range of Motion, Articular; D013848:Thigh