Internal Fixation Part 2 - Fracture Biomechanics

A fracture heals biologically. But biology is governed by mechanics. Bone cells are mechanosensitive. They respond to motion, strain, compression, shear, and tension. And that means one central truth: The surgeon is not simply fixing bone. The surgeon is engineering the conditions under which biology can succeed. Strain in terms of bone healing describes the amount of motion relative to the fracture gap. Too much strain, and the local biology will favor granulation tissue formation. Small amounts of strain will lead to cartilage or callous formation, and very little strain sets up the environment for bone formation. The surgeon is tasked with determining the fracture needs - sometimes absolute stability (low strain) is required and sometimes relative stability. For example, in deformity correction and reconstructive surgery, the desire is to create absolute stability. In certain fracture scenarios, such as comminution, relative stability is preferred to allow the multiple fragments to unite without excessive compression and without further devitalizing bone. The choice of fixation- the construct, the materials, and the placement - are all variables a surgeon puts together in the operating room depending on the specific circumstances.  The content of this podcast is for educational and informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.