Fig. 1

Methodology of classifying the trochlear groove tracking in terms of morphology. Three planes were established in three-dimensional models of the knee, constructed based on computed tomography data. A cylinder with its axis parallel to both the coronal and transverse planes was defined, and its radius was adjusted to allow the cylindrical surface to closely fit the trochlear groove. Coaxial cutting planes rotating in 15° increments (from 45° to 90°) about the trochlear groove axis (from the proximal to distal point) were defined. Subsequently, the deepest point of the trochlear groove was marked in each cross section. The distance from the turning point of the trochlear groove to the mechanical axis was measured (represented by d)