Lipping fractures of the tibia merit consideration as a separate entity because of the difficulty of maintaining reduction and the high degree of disability accompanying union in malposition.
There are two types of these fractures, the anterior and the posterior. There may be an accompanying fracture of the internal malleolus or lower end of the fibula or both, with displacement of the astragalus and foot forward or backward. In the young, there may be a separation of the epiphysis, with lipping fracture of the diaphysis.
The anterior fracture is caused by a sudden violent overflexion of the foot. This might occur when the weight of the body is unexpectedly thrown on the ball of the foot, as, when in stepping up onto a curb or stair, the foot slips off and is forced upward. The astragalus is forced forward and upward. Its convex anterior articulation meets resistance against the