Bone not healing? Is it receiving the correct stimulus?

I recently had the privilege to work with an individual who had suffered an ankle injury.  As a result of this injury the Fibula had suffered a fracture and was not healing.  Upon inquiry as to why, they were perplexed and stated they had not received any good answers as to why.  Here is another thought…

Bone growth is stimulated by weight bearing.  Each bone is designed to resist forces specific to the area in which the bone lives.

 

For example the tibia has great compressive strength but less strength when challenged with a lateral force.

 

So if I wanted to ‘break’ a tibia I would not load it from the top down or bottom up.  To ‘break’ a tibia I would load it from side to side.

Likewise a Fibula is designed to absorb and transfer stresses from top down and bottom up.  My question then becomes what is creating rotatory or side-bending forces in the Fibula.

As a result of the ankle injury the ankle had

Image result for calf stretch

become stiff and unable to bend (dorsiflex).

 

When this person would walk and the involved foot traveled behind them the foot would turn out.  This turning out of the foot was introducing excessive side-to-side and rotatory forces to the Fibula essentially ‘gaping’ the wound.

In theory, upon restoring the ankle mobility (talocrural, subtalar), and normalizing gait, the correct compressive forces at the fibula will help to provide the correct ‘weight bearing’ stimulus for the bone to heal while limiting the shear forces introduced by compensations from a stiff ankle.  Just something to ponder.

 

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