Sulcus angle (knee)

The sulcus angle is formed by the trochlear opening of the knee, measuring the angle between the medial and lateral facets. Classically described in axial x-rays of the knee performed at 30-45º of flexion (skyline view), it is valuable in both CT and MR studies.

Interpretation

Its normal value is 135 ± 10º. When the angle of the groove is >145-150º, trochlear dysplasia can be diagnosed. This condition reflects an incongruence in the patella's sliding over the femoral trochlea, which can result in patellofemoral instability.