Reliability of hand-held dynamometry and its relationship with manual muscle testing in patients with osteoarthritis in the knee.

Support for this study was provided by the Arthritis Health Professions Association, Arthritis Foundation, National Office, and NIH (NIAMS) Multipurpose Arthritis Center Grant No. AM 30692. The reliability of data gathered with hand-held dynamometers (HHD) and the relationship between HHD measurements and manual muscle tests (MMT) have been assessed only with healthy subjects and patients with neuromuscular disorders, not with homogeneous groups of patients with orthopaedic problems. In this study, HHD and MMT were used to measure the strength of knee extensor muscles of 43 patients with osteoarthritis. Test-retest reliability of HHD was determined, and the two testing systems were compared. The HHD measurements indicated that the knee extensor muscles were weak; the MMT grades indicated good strength. The HHD intraclass correlation coefficient for knee extensor strength measurements was 0.92. The HHD measurements increased as the MMT grades increased. The Kendall tau correlation coefficient between HHD measurements and MMT grades for the knee extensor muscles was 0.24. Hand-held dynamometry is less subjective than MMT, especially at the stronger grades. For the purpose of documenting progress of patients, HHD provides a reliable, quantitative method. The use of HHD with weak examiners, weak patients, and inadequate trunk stabilization is questionable. Hand-held dynamometry is useful for clinical and research settings where isokinetic testing is either unfeasible (ie., home care) or cost-prohibitive. J Orthop Sports Phys Ther 1992;16(3):145-149.