Effect of Ankle Dorsiflexion Range of Motion on Rearfoot Motion During Walking.

Effect of Ankle Dorsiflexion Range of Motion on Rearfoot Motion During Walking Cornwall MW, McPoil TG (Gait Research Laboratory, Department of Physical Therapy, Northern Arizona University, Flagstaff, Ariz), J Am Podiatr Med Assoc. 1999;89:272-277.

This study was designed to evaluate the proposed relationship between decreased ankle dorsiflexion range of motion (ROM) and increased subtalar pronation. The authors measured passive non-weight-bearing dorsiflexion ROM with the knee in the extended position in 87 subjects. They placed those subjects with 10 degrees of motion or less into a limited range group (n=43) and those with 15 degrees of motion or more into the normal range group (n=44).

Each subject walked along a walkway at a self-selected speed for 5 consecutive trials while measurements were recorded for angular position data using electromagnetic motion analysis. The temporal events of heel strike, foot flat, heel-off, and toe-off were recorded on 4 sensing switches secured to the plantar surface of the subject's feet. The reference point for all angular measurements was recorded from sensors on the anterior tibial tubercle and the posterior calcaneus bone while the subject stood relaxed with knees extended and feet positioned parallel to the plane of motion. Data analysis included intraclass correlation coefficients for between-trial reliability of the duration of each stance phase, between-trial consistency of the motion patterns, stance phase duration, timed heel-off, angle at heel strike, maximum angle, time to maximum angle, and time to reinversion.

The authors found that there was adequate between-trial consistency for the angular displacements. The only values that were found to be significantly different between the 2 experimental groups were the time to reinversion and the time to heel-off. Subjects in the limited range group reinverted 6.2% sooner and had heel-off 2.8% sooner than those in the normal range group. The subjects dorsiflexed 6.9 [+ or -] 3.9 degrees from a relaxed standing position during the stance phase of walking regardless of their group assignment.

The authors believed that approximately 7 degrees of dorsiflexion from the resting standing position are needed for walking gait. They concluded that a mild to moderate loss of passive dorsiflexion had little or no effect on the frontal plane function of the rearfoot during the stance phase of walking. They suggested that the compensation for mild equinus conditions might take the form of changes in timing (eg, earlier reinversion of the rearfoot, earlier heel-off time) rather than the amount of heel movement. They suggested that future research should examine subjects with greater limitations of dorsiflexion ROM as well as the effects of limited dorsiflexion on the midfoot and forefoot.

Robert Tank, PT, ATC
Orthopaedic Associates
Evansville, Ind