Trochlear Groove of the Femur

sulcus trochlearis femoris

The trochlear groove (femoral sulcus) is the central groove of the trochlea on the anterior distal femur that guides the patella during knee flexion and extension. In the normal trochlea, the groove is well-defined with a prominent lateral facet that prevents lateral patellar tilt; the medial facet is smaller and shallower. Trochlear dysplasia describes abnormal morphology ranging from a shallow groove to a convex boss (crossing sign on lateral radiograph).

Region: Thigh

Clinical Relevance

Clinical Notes

Trochlear dysplasia is the most significant predisposing factor for recurrent patellar instability, more important than MPFL laxity or tibial tubercle lateralisation alone. The Dejour classification (A-D) grades dysplasia from a shallow groove to a complete convex boss with prominence. CT and MRI measure trochlear depth, sulcus angle, and facet symmetry. Trochleoplasty (surgical deepening of the trochlear groove) is indicated for severe Dejour C-D dysplasia with recurrent instability, combined with MPFL reconstruction and tibial tubercle osteotomy in most cases.

Pathology

Common Injuries & Conditions

Recurrent Patellar Instability from Trochlear Dysplasia

Shallow or convex trochlear groove (Dejour B-D dysplasia) fails to contain the patella in the sulcus during knee extension, producing lateral patellar subluxation and dislocation; trochleoplasty by sulcus deepening restores the lateral wall height and groove depth that allows the patella to engage the trochlea in early flexion.