Review Question - QID 9012

The patient presents with an extra-articular distal tibia fracture and undergoes bridge plating. This method of fixation relies on endochondral bone formation through chondrocyte activity (secondary bone healing).

Fracture healing relies on complex interplay of biochemical and mechanical factors and can occur through intramembranous (primary bone healing)and endochondral bone formation (secondary bone healing). Primary bone healing relies on anatomic reduction, compression, and very little strain at the fracture site to allow for Haversian remodeling (development of cutting cones). Absolute stability constructs lead to primary bone healing. Alternatively, secondary bone healing occurs in the periosteum and soft tissues in slightly higher strain environments. Relative stability constructs, such as intramedullary nails, external fixators, and bridge plates are examples of fixation that rely on secondary bone healing.

Perren reviews the biological and mechanical properties of bone remodeling and the complex interplay of patient, injury and surgical factors that influence healing. The use of relative stability fixation techniques allows bone to overcome the initial excess strain at a fracture site and build a scaffold that brings the strain to more reasonable levels. The author stresses the importance of understanding bone biology to select optimal implant and methods of surgical fixation.

Figures A and B are AP and lateral radiographs, respectively, showing a comminuted distal tibia fracture. Figures C and D are post-operative radiographs after use of a bridge plating technique.

Incorrect Answers:
Answer 1: This is usually required for primary bone healing
Answer 3: Cutting cones are seen in Haversian remodeling during primary bone healing
Answer 4, 5: Intramembranous bone formation occurs during primary bone healing and would not be present in this case.