Measurement of the motion range in the loaded ankle.

In an easily practicable method of measuring the motion range in the ankle under load, the patient is asked to put his foot on a 30-cm-high stool and then lean forward as much as possible without lifting his heel from the supporting stool. In this position the knee is flexed and the greater part of the body weight is on the examined foot. Dorsal extension is then measured with a protractor as the angle between the support line of the foot and the long axis of the leg. The loaded plantar flexion is measured in the same position but with the heel raised as much as possible. In a study of 317 healthy ankles, this method was found to give greater and more reproducible values than measuring on unloaded ankles in sitting or supine positions. Measurements of the loaded dorsal extension were also made on radiographs of 66 healthy ankles. The mean value was 32.5 degrees; the mean talar forward tilt was 5.0 degrees. In normal daily life, at least 10 degrees are required; for performing athletics and sports activities, a loaded dorsal extension range of 20 degrees-30 degrees is necessary.