The Calcaneo Cuboid Locking Mechanism

Do you know what this is? You should if you walk or run!

It is the mechanism by which the tendon of the peroneus longus travels behind the lateral malleolus of the ankle, travels underfoot, around the cuboid to insert into the lateral aspect of the base of the 1st metatarsal and adjacent 1st cunieform.

When the peroneus longus contracts, in addition to plantar flexing the 1st ray, it everts the cuboid and locks the lateral column of the foot, minimizing muscular strain required to maintain the foot in supination (the locked position for propulsion). Normally, muscle strength alone is insufficient to perform this job and it requires some help from the adjacent articulations.

In addition, the soleus maintains spuination during propulsion by plantar flexing and inverting rear foot via the subtalar joint. This is assisted by the peroneus brevis and tertius which also dorsflex and evert the lateral column, helping keep it locked. Can you see why the peroneii are so important?

Signs of a faulty calcaneo cuboid locking mechanism:

-weak peroneus longus, brevis and or tertius

-excessive rear or midfoot pronation

-low arch during ambulation-poor or low gear “push off”

-subluxated cuboid

The calcaneo cuboid locking mechanism. Essential for appropriate supination and ambulation. Insufficiency, coming to a foot you will soon examine.

Would you like to know more? Join us for our “third Wednesdays“ online webinar: Biomechanics 313. Wednesday, June 18 at 6 MST. Onlinece.com

So you want to do a Gait Analysis: Part 4

This is the 4th in a multi part series. If you missed part 1, click here. For part 2, click here, part 3, click here. 

These are the basics, folks. We hope this is a review for many.

A quick review of the walking gait cycle components:

There are two phases of gait: stance and swing. 

Stance consists of:

• Initial contact
• Loading response
• Midstance
• Terminal stance
• Pre-swing

Swing consists of:

• initial (early) swing
• mid swing
• terminal (late) swing

today, lets explore Terminal stance

Terminal stance is one of the last stages of stance phase. Following midstance, where maximal pronation should be occurring, the stance phase foot should now begin supinating, initiated by the the opposite foot in swing phase moving forward of the center of gravity. 

Lets look at what is happening here at the major anatomical areas:

Foot

• Supination begins from the opposite, swing phase leg (see above)
  

•  the calcaneus inverts to neutral

•  the center of gravity of the foot raises from its lowest point at midstance

• The lower leg should begin externally rotating (as it follows the talus)

• The thigh should follow the lower leg and should also be externally rotating; sometimes to a greater extent due to the shape and size of the medial condyle of the femur (which is larger than the lateral)

• these actions are perpetuated by the gluteus maximus and posterior fibers of the gluteus medius, as well as posterior compartment of the lower leg including the flexor digitorum longus, flexor hallucis longus, peroneus longus and tibialis posterior

Ankle

• The ankle should be 5 degrees dorsiflexed and in ankle rocker
• the calcaneocuboid locking mechanism should be engaging to assist the peroneus longus in getting the head of the 1st metatarsal to the ground

Knee

• near or at full extension. This is perpetuated by the quadriceps and biceps femoris, contracting concentrically and attenuated by the semi membranosis and tendonosis. The popliteus contracts eccentrically as soon as the knee passes midstance to keep the rates of external rotation of the tibia and femur in congruence.

Hip

• The hip should be extending to 10 degrees.

Can you picture what is happening? Try and visualize these motions in your mind. Can you understand why you need to know what is going on at each phase to be able to identify problems? If you don’t know what normal looks like, you will have a tougher time figuring out what is abnormal.

Ivo and Shawn. Gait and foot geeks extraordinaire. Helping you to build a better foundation to put all this stuff you are learning on.

pictured used with permission from Foot Orthoses and Other Conservative Forms of Foot Care