For our purposes here forefoot valgus is defined as a deviation in the frontal plane when the subtalar joint is held in the defined neutral position and the lateral forefoot is loaded or dorsiflexed, resulting in a forefoot that is everted relative to a bisection of the posterior aspect of the calcaneus. It is essentially the opposite of the defined forefoot varus.
There are other definitions of a forefoot valgus, but that is the one that I use here and mean when I say “forefoot valgus”. When you see the term forefoot valgus mentioned, double check exactly what they think they mean when they say forefoot valgus.
A forefoot valgus could be due to a number of things. For example:
- an over-rotation of the head and neck of the talus during its ontogeny development can lead to the forefoot valgus (an under rotation leads to a forefoot varus)
- a first ray or metatarsal that is plantar flexed can lead to a forefoot varus (this could be due to eg an osseous plantarflexion or a contracture of the peroneus tendon).
When a forefoot valgus is weightbearing, the forefoot will want to invert to get itself flat on the ground. This can happen in one of two ways:
- if there is a good range of motion in the midfoot joints the forefoot will simply invert on the rearfoot and give the appearance of a flattening of the arch
- if there is a restriction of motion in the midfoot joints, then the inversion motion of the forefoot will invert to supinate the rearfoot at the subtalar joint, giving the appearance of a high arch foot.
What ever you want a forefoot valgus to be, please make sure you are using a clear definition. I acknowledge that there are other definitions used by others. The one above is the one that I use. You can use what ever one you want to.