Measurement and comparison of tibial posterior slope angle in different methods based on three-dimensional reconstruction

BackgroundThe tibial posterior slope (PTS) is an important parameter for sagittal alignment which is associated with postoperative range of motion. However, the variations of different population subsets and different referential axes are still uncertain.MethodsIn this study, 80 healthy people from South China were recruited and measured on three-dimensional reconstruction of CT, with application of three referential axes, the proximal tibial long axis, the anterior and posterior cortices.ResultsThe averages and standard deviations of medial PTS (MPTS) in the three methods were 8.43 ± 3.06, 11.45 ± 2.82 and 6.31 ± 3.24, separately. The results of lateral PTS (LPTS) were 7.56 ± 2.51, 10.17 ± 2.42 and 5.22 ± 2.59. There was no significant difference between the male and the female, and the two sides of one body. The results of the three axes varied but correlated with each other significantly. Through comparison it was found that, MPTS/LPTS of people from South China were different from the published data of other countries.ConclusionsAlthough PTS change markedly according to the reference axis, they show significant correlations with each other, and may be used safely. There are differences associated with races, but not gender nor the two sides of the body.Clinical relevanceThe results of the study provided references for the reconstruction of the knee PTS, if the differences of reference axes, races and genders were considered.