Re-Modelling of North Indian Talus: A Pressure Effect of Squatting Position

The structural changes that a function may bring about like morphological differences observed between bones of different populations are of much interest. Squatting is a good example of such behaviour/function producing skeletal markers on the bones. The squatting position puts strong pressure and traction forces on the knee and ankle joints, producing specific bone markers that reflect the remodelling of bone occurring in response to physical stress. These morphological changes are most pronounced in those races in which it is the customary mode of resting. Squatting is the position in which the legs are flexed upon the thighs and the thighs on the trunk. In this posture the back of the thighs rests upon the calf and the knee-joint is in a state of extreme flexion, associated with a certain degree of rotation of the leg upon the thigh. The heels are apart about the distance that separates the ischial tuberosities. The fronts of the ischial tuberosities are in close apposition with the heel; in fact the trunk weight is supported mostly by the heels and backs of the tibiae. Habitual squatting alters the skeletal morphology of lower limb. It is associated with modifications of the neck of the talus (squatting facets) and its trochlear-malleolar surfaces (trochlear extensions). Thomson first described the presence of squatting facets on the anterior margin of the distal extremity of the tibia and the upper surface of the neck of the talus of Australian and Andamanese human specimen along with other primates [1]. Since then, these facets have been studied in different groups of populations in both ancient and present-day by various authors [2-10]. According to Barnett [2] and Oygucu [3] a number of types of true squatting facets can be found on the neck of the talus. In addition, anterior extensions of the trochlear and malleolar surfaces of the talus that are continuous with the normal surfaces may be present. Usually Indians assume squatting position conveniently during washing, cleaning, making pottery or handicrafts, working in fields, even resting. The Indian style toilets require to squat for defecating. This is not so in the western countries where squatting posture is not a part of their regular behaviour. The occurrence of talar modifications was therefore investigated in adult Indian talus.