An Investigation into Reliability of Knee Extension Muscle Strength Measurements, and into the Relationship between Muscle Strength and Means of Independent Mobility in the Ward: Examinations of Patients Who Underwent Femoral Neck Fracture Surgery

[Purpose] The purpose of the present study was to investigate the reliability of isometric knee extension muscle strength measurement of patients who underwent femoral neck fracture surgery, as well as the relationship between independent mobility in the ward and knee muscle strength. [Subjects] The subjects were 75 patients who underwent femoral neck fracture surgery. [Methods] We used a hand-held dynamometer and a belt to measure isometric knee extension muscle strength three times, and used intraclass correlation coefficients (ICCs) to investigate the reliability of the measurements. We used a receiver operating characteristic curve to investigate the cutoff values for independent walking with walking sticks and non-independent mobility. [Results] ICCs (1, 1) were 0.9 or higher. The cutoff value for independent walking with walking sticks was 0.289 kgf/kg on the non-fractured side, 0.193 kgf/kg on the fractured side, and the average of both limbs was 0.238 kgf/kg. [Conclusion] We consider that the test-retest reliability of isometric knee extension muscle strength measurement of patients who have undergone femoral neck fracture surgery is high. We also consider that isometric knee extension muscle strength is useful for investigating means of independent mobility in the ward.