By Drs Jacqueline Munch Brady and Nicholas Paschos We began our journey in beautiful Lyon, France with Dr David Dejour. We focused on instability, discussing the principles of clinical and radiographic evaluation of the patellofemoral joint, and indications for procedures such as distalizing tibial tubercle osteotomy and trochleoplasty. Dr. Dejour explained the thought process behind identifying patella alta and/or trochlear dysplasia as the major contributing factor to instability, and correcting each accordingly. Dr. Philippe Neyret was our next host, across the city in Lyon. With him, we shifted our focus to the extensor mechanism of the knee, discussing considerations for surgical intervention in chronic quadriceps or patellar tendon insufficiency. He demonstrated a technique for complex reconstruction of a deficient patellar tendon using mesh augmentation, for instances where the native tendon is insufficient for repair. Next, we stopped in London to visit Dr. Andrew Amis. His lab at the Imperial College is equipped to study everything from soft tissue anatomy to complex joint kinematics. We discussed the difficulties in studying the patellofemoral joint biomechanically: for instance, a dearth [...]