- Type I:
- comminution is minimal or there is no comminution at frx site
- Type II:
- comminution involves a fragment larger than that in type I but has at least 50% of the circumference of the cortices of two major frx fragments intact;
- broad cortical contact following frx reduction & nailing prevents shortening & malrotation, simple IM nailing suffices for most type II frx;
- Type III:
- injuries, between 50 and 100% of the circumference of two major frx fragments is comminuted;
- such large butterfly fragments compromises frx fixation since broad cortical abutment of major frx fragments is impossible;
- simple intramedullary nails are insufficient for type III frx and must be supplemented with interlocking screws, cerclage wires, or post operative traction or bracing;
- Type IV:
- all cortical contact is lost in type IV injuries;
- cortex is circumferentially comminuted over a segment of bone;
- even w/ intramedullary nailing, there is no contact between proximal and distal fragments; all inherent stability of fractue is lost