Foot Shape Variations

Natural Variation

As with all things in nature, there are variations in this untwisting process. Very rarely is the exact degree of torsional untwisting for the calcaneus (heelbone) and talus achieved.

The degree of torsional untwisting is variable, and is normally different in the rearfoot and forefoot of each foot. The result is a natural foot shape combination, unique to each foot, where the foot retains some degree of torsional twisting about the vertical (rearfoot)and/or horizontal axes (forefoot).

Because the structural alignment of the calcaneus and talus is set by the end of the 1st Trimester of pregnancy, such foot shape variations are termed congenital, meaning present at birth. The physical bony alignment present at birth remains unchanged through life.

Types

There are two types of foot shape:

• a natural Varus, or inverted shape created as a result of insufficient torsional untwisting;
• a natural Valgus, or everted foot shape created as a result of excessive torsional untwisting.

Varus and Valgus deformities can affect both the calcaneus and the talus, as shown below:

NATURAL FOOT SHAPE VARIATIONS	Varus (Insufficient Untwisting)	Valgus (Excessive Untwisting)
Calcaneus (controls position of rearfoot)	Rearfoot Varus	Rearfoot Valgus
Talus (controls position of forefoot)	Forefoot Varus	Forefoot Valgus

Click here for a summary of the different foot shapes and altered foot function

Cause

The cause for variations in the degree of torsional untwisting of the calcaneus and/or talus is as yet unknown.