A, Type I, pure cleavage fracture. B, Type II, cleavage combined with depression. Reduction requires elevation of fragments with bone grafting of resultant hole in metaphysis. Lateral wedge is lagged on lateral cortex, protected with buttress plate. C, Type III, pure central depression. There is no lateral wedge. Depression also can be anterior or posterior or involve whole plateau. After elevation of depression and bone grafting, lateral cortex is best protected with buttress plate. D, Type IV. Medial condyle is split off as wedge (type A) as illustrated, or it can be crumbled and depressed (type B), which is characteristic of older patients with osteoporosis (not illustrated). E, Type V. Note continuity of metaphysis and diaphysis. In internal fixation, both sides must be protected with buttress plates. F, Type VI. Essence of this fracture is fracture line that dissociates metaphysis from diaphysis. Fracture pattern of condyles varies, and all types can occur. If both condyles are involved, proximal tibia should be buttressed on both sides.