The aim of this study was to determine the anatomic proximal tibial posterior slope angle by measuring the true posterior slope angle of the proximal tibia and the meniscal slope angle by MRI.

We measures 102 meniscal and tibial plateau slope angles, including 39 medial and 63 lateral sides. The average age of the patients was 33.3 years (8-66). We measured the meniscal slope angle form MRIs of the patients, with confirmed no pathologic abnormality of the meniscus by arthroscopy. We traced the line between the upper margins of the anterior and posterior horn of the medial and lateral menisci, and the proximal tibial plateau line. The angle between the two lines was considered as the meniscal slope angle.

The medial meniscal slope angle between the medial meniscal slope and the medial tibial bony slope averaged 6.2 ° (2.5-9) and 5.3 ° (1-15) in the lateral, side, an overall average angle of 5.8 °.

This results suggests that the proximal tibial meniscal slope is less oblique than the usually measured bony slope at about 5.8 °. The authors suggest the proximal tibial cutting slope with 5.8 ° less posterior tilt than bony slope angle.