Relationship of patella to trochlear groove
The groove contains the patella within its walls as the knee bends and straightens.
Factors Affecting Tibial Tuberosity-Trochlear Groove Distance in Recurrent Patellar Dislocation. Prakash J, Seon J-K, Ahn H-W, Cho K-J, Im C-J and Song EK. Clin Orthop Surg. 2018 Dec; 10(4): 420–426.