Objective: To determine the correlation between strength and functional measures, and the intercorrelation between the functional measures themselves, in a group of subjects with diabetes mellitus (DM) and transmetatarsal amputation (TMA).
Design: Correlational study.
Setting: The subjects were tested in the Applied Kinesiology Laboratory of the Program in Physical Therapy at Washington University School of Medicine, St Louis, MO, USA.
Subjects: Thirty subjects with DM and TMA (mean age 61.7 +/- 11.3 years) were studied.
Main outcome measures: Function was measured using the Functional Reach Test (FR), the Physical Performance Test (PPT), the Sickness Impact Profile (SIP), and walking speed (WS) for 15.24 m. Strength measurements were taken using a hand-held dynamometer.
Results: Highest correlations were found between hip extension strength and PPT: r = 0.69, FR: r = 0.45, and WS: r = 0.76, between knee extension strength and PPT: r = 0.48, and WS: r = 0.51, between hip flexion strength and PPT: r = 0.51, FR: r = 0.47, and WS: r = 0.59, between knee flexion strength and PPT: r = 0.57, and WS: r = 0.63, and between dorsiflexion strength and PPT: r = 0.49, and WS: r = 0.63. The following intercorrelations between functional measures were significant; PPT and FR: r = 0.66, PPT and SIP: r = -0.54, PPT and WS: r = 0.77, FR and WS: r = 0.54, SIP and WS: r = -0.47.
Conclusions: The relationship between measures of hip and knee muscle strength and function provides some evidence that rehabilitation should focus on strengthening hip and knee extensors and flexors to improve function. The relationships between walking speed and strength, PPT, FR and SIP suggest that the simple measure of walking speed is a useful functional test in the clinic.