SHould You TransFer the Tubercle?

This study — called SHAFT — is testing whether a surgical procedure called tibial tubercle transfer (TTT) leads to better outcomes compared to MPFL (medial patellofemoral ligament) reconstruction alone for young people with recurrent kneecap dislocations. When the kneecap repeatedly slips out of place (lateral patellofemoral instability), it causes significant pain, fear of movement, and sometimes cartilage damage. The choice of surgery depends partly on anatomical factors, and this trial will help clarify when the more involved bone-moving procedure is actually worth the additional complexity. To be eligible, you must be between 13 and 30 years old with a confirmed history of recurrent lateral kneecap instability, a specific anatomical measurement called TT-TG of 15 mm or more on MRI (or 18 mm on CT), and growth plates that are already closed (confirmed on x-ray). You are excluded if you have a very high kneecap position, excessive femoral or tibial rotation, severe trochlear dysplasia, significant arthritis, or an active cartilage repair procedure planned. Participants will be assigned to one of two surgical approaches and followed over time to measure pain, function, and recurrence of dislocation. Recurrent kneecap dislocation is most common in teenagers and young adults — a demographic for whom missed sports seasons, fear of injury, and prolonged rehabilitation carry real costs. Finding the right surgery for the right patient at this pivotal age could dramatically improve long-term joint health and activity levels.