Anatomy TUESDAY – The Foot/Ankle Complex (Part 5) – Metatarsophalangeal Joints

Moving distally in our exploration of the foot, we encounter the metatarsophalangeal(MTP) joints. If the previous joints were dominant in pronation/supination, the MTP joints are dominant in the sagittal plane, providing the flexion/extension needed to absorb shock and push off. And the most important is the first MTP joint of the great toe.

Notice the small sesamoid bones that are only located under the first metatarsal. These bones increase the mechanical advantage of flexor hallucis longus (FHL). The anatomy books tell us that the FHL flexes the great toe, but when the foot hits the ground, its primary job is deceleration of great toe extension.

Upwards of 70-90 degrees of extension is necessary for normal push-off of the great toe, with the other toes contributing 40-60 degrees of extension. Test this on yourself. Grab your big toe and bend it backwards. Do you have close to 90 degrees of motion?

A lack of great toe extension results in one of the following compensations:

Increased toe-out resulting in hallux valgus (bunion) over time
Over supination of the foot/ankle to avoid extending the great toe (if painful)
Shortening of the opposite stride length
Increased strain on the gastrocnemius (calf) muscle

All of these compensations have ramifications up the biomechanical chain:

Pelvic rotation towards the side of decreased toe extension
Chronic tightness in psoas major
Increased knee flexion forces

The MTP joints also contribute 45 degrees of flexion

Why does this matter?

Wiggling your toes begins at the MTP joints, the first set of foot joints dominant in the sagittal plane. A lack of wiggle here may create chaos up the biomechanical chain. It is the reason I am a fan of toe socks and this yoga toes series of exercises.

It’s easy to forget to wiggle your toes when they are jammed in shoes all day long. As clinicians, it is imperative we evaluate MTP function in any patient with lower extremity injuries. Lack of motion here echoes loudly in the knee, hip and low back. Another small joint that packs a big punch. Get wiggling.

Because nobody has time to be in pain.

Until next time…