- Discussion:
- theory based on reproduction of frx patterns in cadavera;
- rationale was to guide closed treatment of fractures about the ankle;
- initial position of the foot is either supination or pronation;
- supination of foot places tension on lateral structures of ankle;
- pronation places tension on medial structures;
- deforming force is either rotational (internal or external) or translational (abduction or adduction);
- Supination External Rotation:
- injury begins anteriorly and progresses by external rotation around ankle;
- structures that are damaged are, in order:
- anterior tibiofibular ligament; (type I)
- lateral malleolus (type II)
- posterior aspect of capsule or posterior malleolus (type III)
- medial malleolus or Deltoid Ligament (type IV)
- Pronation External Rotation:
- frx begins on medial side of ankle, which is tightened by pronation;
- injury progresses by external rotation around ankle w/ damage occuring from medial to lateral in mirror image of SER frx