A
Primary bone healing via Haversian remodeling
B
Secondary bone healing via callus formation
C
Direct intramembranous ossification
D
Creeping substitution
Explanation:The correct option is 'b'. In highly comminuted fractures, anatomic reduction of every fragment is impossible and devascularizes the bone. Bridge plating uses locking screws to create a fixed-angle construct spanning the comminuted zone. This provides 'relative' flexibility (micro-motion) at the fracture site, which stimulates chondrogenesis and subsequent endochondral ossification, leading to secondary bone healing characterized by visible callus formation.
Reference: Perren SM. Evolution of the internal fixation of long bone fractures. The scientific basis of biological internal fixation: choosing a new balance between stability and biology. J Bone Joint Surg Br. 2002;84(8):1093-1110.