Abstract: To determine the reproducibility of isokinetic and isometric hip
flexion, extension, abduction and adduction strength scores in patients with
hip osteoarthritis (N=16) and healthy subjects, testing
was conducted twice 7 days apart. The patient group (PG) consisted of 16
subjects with unilateral or bilateral osteoarthritis of the hip (11 women, 5
men; age 56–75y). The control group (CG) included 13 age-matched healthy
subjects (9 women, 4 men; age 54–73y). The standard error of measurement (SEM)
served as the reproducibility outcome parameter. The highest SEM values were
obtained for hip extension measurements (15.4–16.7 Nm), followed by hip
adduction (7.9–11.8 Nm) and hip flexion measurements (5.2–7.5 Nm). The
smallest values were quantified for hip abduction measurements (4.7–7.7 Nm).
PG showed larger values in all isometric measures except for hip extension and
isokinetic hip abduction. When the 95% confidence interval is incorporated,
these SEMs become significant. Thus clinicians should be aware of the large measurement error in patients with hip OA. Adequate preparations and firm
fixation of the pelvis are key elements to achieve reproducible results.
Keywords: Dynamometer, muscle strength, hip osteoarthritis, reproducibility
