Bone loss and forms of tibial condylar fracture.

Bone loss and fracture type were determined in 358 tibial condylar fractures. Degree of osteoporosis at the knee was defined by analogy to Singh's grades of osteoporosis at the hip and to Jhamaria's classification of osteoporosis at the calcaneum: grade V-normal; grade IV-slight reduction of trabecular bone; grade III-osteoporosis, predominantly of trabecular bone; grade II-osteoporosis of trabecular and cortical bone. Five fracture types were distinguished, with the component of trabecular bone compression increasing from a to e: a-pure split fractures; b-split fractures with displacement of a piece of the articular surface; c-split compression fractures; d-local compression fractures; e-compression of a whole condyle. There was a highly significant rank correlation between the two sets of ordered categories. Fractures in osteoporotics tended to involve the lateral condyle; this is explained by the fact that crush fractures occurred more frequently at the lateral condyle. The influence of bone loss on fracture type was demonstrated to be independent of age. A clear understanding of these associations concerning three variables at a time was reached by the use of log-linear-model analysis for cross-classified qualitative data.