Influence of soft tissues on the proximal bony tibial slope measured with two-dimensional MRI.

PURPOSE

Despite increasing interest in the functional anatomy of the menisci, little information is available regarding the relationship between the tibial slope and the menisci. It was hypothesized that the meniscus would reduce the differences in slope between the medial and lateral compartments and would mitigate the effects of age and gender on the tibial slope.

METHODS

MRI sagittal images from 101 patients were used in this study. The angle between a line tangent to the medial and lateral tibial bony slope and the proximal tibial anatomical axis was measured on sagittal MRI images (bony slope). The angle between the tangent line to the highest point of the anterior and posterior horn of the meniscus and the proximal tibial anatomical axis was also determined (soft tissue slope). The measurements were carried out twice by two observers. The influence of gender and age on these parameters was analysed.

RESULTS

Repeated measures analysis of variance showed good inter- and intra-observer reliability for both bony and soft tissue slope (ICC (0.87-0.93) and (0.91-0.97) for inter- and intra-observer reliability, respectively). In both compartments, the soft tissue significantly reduced the tibial slope towards the horizontal plane. In addition, the soft tissue slope was significantly more horizontal in the lateral compartment compared to the medial compartment (p < 0.01). These differences were not influenced by age or gender.

CONCLUSION

The menisci of the knee generate a more horizontal tibial slope when measured on MRI. The soft tissue slope is more horizontal in the lateral compartment of the knee compared to the medial compartment.

LEVEL OF EVIDENCE

Diagnostic, Level III.