The Great Toe Valgus
by Alison McGinnis, PT, DPT, FAFS
New research confirms what PTs have already known: as the big toe moves in towards the second toe (great toe valgus angle) the foot pronates more and the knee moves inwards more (knee valgus) leading to knee pain in runners.
The big toe plays an important role in foot stability and joint control up the chain when walking or running. The big toe should follow a straight line out from the heel along what’s called the Meyer’s Line. As the big toe moves towards the 2nd toe, the angle between the toe and this line increases causing the stability of the foot to decrease. Typically this angle is also associated with the formation of a bunion. Increased great toe valgus occurs over time due to the shape of our current footwear, where the toe box is narrowed and the ends of the toes are squeezed together.
As great toe valgus increases, the amount of pronation that occurs in the foot was found to increase. And this in turn led to an increase in frontal plane knee motion.
As the big toe moves in towards the second toe:
↳ the arch drops down and inward,
↳ the tibia internally rotates,
↳ the knee gets pulled inward in a chain reaction.
This motion is normal in all humans to some degree, but increases significantly as the great toe angle increases.
Altered frontal plane control during the stance phase of running increases the risk of patellofemoral knee pain and other overuse injuries along the inside structures of the foot, shin, knee, and hip.
Foot mechanics play a crucial role in the loading mechanics among runners, and addressing any biomechanical issues here can have a significant impact for injury prevention.