[Role and movement of the toes during walking]

In order to understand the function of toes during free walking, movements of the toes of 30 normal adults were measured with the electrogoniometers. The angular changes of the interphalangeal (IP) joint of the 1st toe and the distal interphalangeal (DIP) joints of the 2nd to 4th toes, the ground reaction force, foot switch signal and the pressure changes in the forefoot were recorded simultaneously. The relationships between these measurements were then investigated. During the foot-flat phase, the IP joint of the 1st toe stayed at a flexed position, while the DIP joints of the 2nd to 4th toes remained at a slightly extended or neutral position but there was scarcely any pressure on the toe tips (0-0.3 kg/cm3). After the heel-off, the pressure on the 1st toe tip gained with increasing flexion of the IP joint of the 1st toe. The mean of the maximum angles was 13 +/- 5 (mean +/- SD) degrees. After the heel-off, the DIP joints of the 2nd and 3rd toes remained in the extended position in 16 cases (6.6 +/- 3.1 and 6.3 +/- 3.4 degrees) and appeared to stay at a flexed position in 14 cases (10.0 +/- 7.8 and 8.0 +/- 5.3 degrees). The DIP joint of the 4th toe remained in the extended position in all cases (9.2 +/- 8.5 degrees). The pressure of the toe tips increased. The magnitude of the pressure of the extended toe tips was higher than that in the flexed toe tips. The pressure of the toe tips of the 1st to 4th toes reached the maximum much earlier than that of the toe-off. From these observations, we conclude that the function of the toes during free walking seems to stabilize the foot by extending a contact area with floor mainly after the heel-off.