A real 3D measurement technique for the tibial slope: differentiation between different articular surfaces and comparison to radiographic slope measurement

Abstract

Background 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. Methods 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 measurement. Results 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. Conclusions 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 of evidence Level III, diagnostic study.

Morphological Analysis of the Tibial Slope in 720 Adult Knee Joints

“…The measurement of the TS in lateral radiography is limited. Especially, differences between the medial and lateral knee-joint compartment are not exactly assessable a priori [ 5 , 27 , 40 ]. Our study demonstrated a significantly higher TS on the lateral articular surface, independent of the measurement method that was used.…”

“…The current literature indicates a highly variable intra-individual TS [ 7 , 22 , 26 ]. However, the reference values are based on different imaging procedures and measurement methods [ 5 , 26 , 27 ]. The measurement of the TS in the lateral radiographs of the knee has been described to be limited, because the determination can only be performed on the basis of a single radiological projection [ 5 , 27 ].…”

“…However, the reference values are based on different imaging procedures and measurement methods [ 5 , 26 , 27 ]. The measurement of the TS in the lateral radiographs of the knee has been described to be limited, because the determination can only be performed on the basis of a single radiological projection [ 5 , 27 ]. On one hand, no assumption can be made about the differences between the medial (med) and lateral (lat) TS [ 22 , 27 , 28 ], and on the other hand, the anatomical tibial axis cannot be precisely defined [ 27 , 29 ].…”

“…The measurement of the TS in the lateral radiographs of the knee has been described to be limited, because the determination can only be performed on the basis of a single radiological projection [ 5 , 27 ]. On one hand, no assumption can be made about the differences between the medial (med) and lateral (lat) TS [ 22 , 27 , 28 ], and on the other hand, the anatomical tibial axis cannot be precisely defined [ 27 , 29 ]. In order to achieve the most accurate and compartmentalised assessment of the TS, cross-sectional images in the form of magnetic resonance imaging (MRI) or computed tomography (CT) are recommended [ 30 , 31 , 32 , 33 , 34 , 35 ].…”

Anterior Closing Wedge Osteotomy for Failed Anterior Cruciate Ligament Reconstruction: State of the Art

“…The greatest advantage of a 3D CT scan over radiography is elimination of errors due to the rotational profile of the tibia and accurate analysis by referencing the anatomic axis. 34 Moreover, it allows independent assessment of both medial and lateral plateaus and the peripheral rim with a high degree of reliability and accuracy 35 (Figure 4). The centers of circles touching the anterior and posterior tibial cortices at 5 cm.…”