The tibial slope plays an important role in knee surgery. However,
standard radiographic measurement techniques have a low
reproducibility and do not allow differentiation between medial and
lateral articular surfaces. Despite availability of
three-dimensional imaging, so far, no real 3D measurement technique
was introduced and compared to radiographic measurement, which were
the purposes of this study.
Computed tomography scans of 54 knees in 51 patients (41 males and
10 females) with a mean age of 46 years (range
22-67 years) were included. A novel 3D measurement technique
was applied by two readers to measure the tibial slope of medial and
lateral tibial plateau and rim. A statistical analysis was conducted
to determine the intraclass correlation coefficient (ICC) for the
new technique and compare it to a standard radiographic
The mean 3D tibial slope for the medial plateau and rim was 7.4°
and 7.6°, for the lateral plateau and rim 7.5° and 8.1°,
respectively. The mean radiographic slope was 6.0°. Statistical
analysis showed an ICC between both readers of 0.909, 0.987, 0.918,
0.893, for the 3D measurement of medial plateau, medial rim, lateral
plateau and lateral rim, respectively, whereas the radiographic
technique showed an ICC of 0.733.
LEVEL OF EVIDENCE
The proposed novel measurement technique shows a high intraclass
agreement and offers an applicable opportunity to assess the tibial
slope three-dimensionally. Furthermore, the medial and lateral
articular surfaces can be measured separately and one can
differentiate the slope from the plateau and from the rim. As
three-dimensional planning becomes successively more important, our
measurement technique might deliver a useful supplement to the
standard radiographic assessment in slope related knee surgery.
Level III, diagnostic study.