Supination, anyone? The importance of the calcaneocuboid locking mechanism.

Pronation gets all the press; but what about its yin counterpart, supination? There could not be one without the other.

Pronation is dorsiflexion, eversion and abduction of the foot. It provides shock absorption. Supination is plantar flexion, inversion and adduction. It make the foot into a rigid lever so we can GO (Like in Theo Selig’s “Go Dig Go”. OK, I have been reading that to my kids alot lately…)

Locking of the lateral column of the foot (4th and 5th metatarsal, cuboid and calcaneus) is a necessary prerequisite for normal force transmission through the foot and ultimately placing weight on the head of the 1st metatarsal for proper toe off. Locking of the lateral column minimizes muscular strain as the musculature (soleus, peroneus longus and brevis, EHL, EDL, FDL and FHL) is usually not strong enough to perform the job on its own.

The peroneus longus tendon wraps around the cuboid (and the brevis attaches to the base of the 1st metatarsal) on its way to insert onto the base of the 1st metatarsal. When it contracts, it dorsiflexes and everts the cuboid, which, along with the soleus (which plantar flexes and inverts the subtalar joint) allows dorsiflexion of 4th and 5th metatarsals and “locks” the lateral column.  Without this mechanism, there is no locking. Without locking, there is no supination. Without supination, there is little rigidity and inefficient propulsion.

The calcaneo cuboid locking mechanism. Another cool thing you learned about gait today from The Gait Guys.

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