Abstract: Objective To analyze the difference of posterior condylar offset(PCO) and posterior condylar offset ratio(PCOR) in different sex or level groups and figure out the relationship between the PCO/PCOR and posterior tibial slope(PTS). Methods Totally 200 patients diagnosed with osteoarthritis of knee during February 2018 to June 2018 were rolled in, including 63 men(112 knees) and 137 women(249 knees). The osteoarthritis level was evaluated, PCO and anterior-posterior dimension(ACP) of distal femur was measured and the PCOR(PCO/ACP) was evaluated through anterior and lateral radiographs of the knee. Two-ways ANOVA was used to analyze the difference of PCO/PCOR in different groups, Pearson relation analysis was used to analyze the relationship between the PCO/PCOR and PTS. Results The PCO of male was larger than level-matched female; there was no difference in PCOR between male and female. There was no difference in PCO and PCOR of female among three levels. The male in level Ⅱ have smaller PCO than level Ⅲ and IV (P=0.004, P=0.008), no more difference found between level Ⅲ and IV; and there was no difference exists in PCOR of male among three levels. PCO was not related to PTS in neither sex nor level groups, the relationship between the PCOR and PTS only depends on the level rather than the sex, and this relationship only exists in level Ⅱ(r=0.226 9, P=0.02). Conclusion The osteoarthritis progression has much more influence on male than female. Hyperostosis and osteophyte have no effect on anatomical characteristics of distal femur, but on the anatomical relationship between femur and tibia. The relationship between PCOR and PTS is gradually disappearing with disease progression.

Key words: osteoarthritis of knee, posterior condylar offset, posterior condylar offset ratio, posterior tibial slope