Inter-fragmentary Strain Theory of Perren

• It is defined as “the ratio of relative displacement of fracture ends versus initial fracture gap width”.
• It relates the tissue response to the local mechanical environment.
• ε=d/G where ε-the inter-fragmentary strain, d-fracture ends displacement, & G– gap between ends.
• ε=d/G≤2%        >Bone formation
  ε=d/G≤10%      >Fibrocartilage
  ε=d/G≤100%    >Granulation tissue
  ε=d/G>100%    >No tissue formation
• Disadvantages of the Theory:
  1. Oversimplified theory
  2. Only Longitudinal Strain is considered
  3. Multidirectional principal strains are not even considered.

Advertisement