Reliability and reference values of two clinical measurements of dynamic and static knee position in healthy children
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- Örtqvist, M., Moström, E.B., Roos, E.M. et al. Knee Surg Sports Traumatol Arthrosc (2011) 19: 2060. doi:10.1007/s00167-011-1542-9
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The purposes of this study were to evaluate reliability of the Single-limb mini squat test (a dynamic measure of medio-lateral knee position) and the Quadriceps-angle (Q-angle) (a static measure of medio-lateral knee position), present paediatric reference values of the Q-angle, and evaluate the association between the tests.
Two hundred and forty-six healthy children (9–16 years) were included (intra/inter-rater reliability for Q-angle (n = 37/85) and for Single-limb mini squat test (n = 33/28)). Dynamic medio-lateral knee position was assessed by the Single-limb mini squat test. Static medio-lateral knee position was evaluated by the Q-angle.
The reliability of the Single-limb mini squat test was found to be moderate (kappa 0.48–0.57, 95% CI 0.16–0.85, 76–79% agreement). Fair to moderate reliability (ICC 0.35-0.42, 95% CI 0.11–0.66, SEM 1.4°–1.9°, n.s.) of the Q-angle measurements was found. Reference values for the Q-angle (mean 13.5° (1.9)–15.3° (2.8)) varies with age and gender. No associations were found between dynamic and static measures.
The Single-limb mini squat test showed a moderate reliability and the Q-angle showed a fair to moderate reliability. A difference found for age and gender was lower than 5° and may not be clinical significant. No association were found between the two tests, indicating dynamic and static knee position being two different concepts. In a clinical perspective, we suggest that the Single-limb mini squat test is a contribution to the available tool box for evaluation of dynamic medio-lateral knee position in children, although the Q-angle may not be used before more research has been done justifying its use.
Level of evidence
Diagnostic study, Level III.