Interrater Reliability of Knee Muscle Forces Obtained by Hand-held Dynamometer from Elderly Subjects with Degenerative Back Pain

Abstract

Background and Purpose: We determined the interrater reliability of measurements of knee extensor and flexor muscle strength obtained with a Nicholas Manual Muscle Tester (NMMT) from older adults with chronic low back pain. Methods: Subjects were 25 (17 female and 8 male) patients (68.2±7.7 years) with degenerative back pain for > 6 months. Two female physical therapists measured subjects' isometric knee extensor and flexor muscle force. Knee position was standardized between measures and raters. The order of testers was performed at random. Intraclass correlation coefficients (ICCs) were used to describe the inter-rater reliability for the total sample and for subjects classified into high and low symptom groups according to the Lumbar Spinal Stenosis-symptom severity scale. We compared the interrater reliability of measurements obtained from patients with high and low symptoms. Results: Inter-rater reliability was high for the total sample (0.87–0.93) and both symptoms groups (high symptom [ICC=0.89–0.94]; low symptom [ICC=0.80–0.92]. There was no significant difference in the inter-rater reliability of measures obtained from the high and low symptom groups. Conclusions: Inter-rater reliability is good to high for measurements of knee extensor and flexor muscle force obtained by hand held dynamometry.The reliability is not influenced by symptom severity.