When? Only patients with high-grade trochlear dysplasia types B and D, in which the prominence of the trochlea (supratrochlear spur) is over 5 mm, recurrent patellar dislocation, and maltracking. How? Sulcus deepening trochleoplasty: modifies the trochlear shape with a central groove and oblique medial and lateral facets; decreases the patellofemoral joint reaction force by reducing the trochlear prominence (spur); and reduces the tibial tubercle and the trochlear groove value by a proximal realignment. Pros: This procedure is highly effective in restoring patellofemoral stability and satisfying the patients. Cons: The patients must be aware of the risk of continuing residual pain and range-ofmotion limitation and that the development of patellofemoral osteoarthritis is not predictable.