Abnormal patella morphology Patella alta 2022-02-26T13:06:28Z Patella alta is a patella that rides abnormally high in relation to the femur, the femoral trochlea, or the tibia, with decreased bony stability requiring increased knee flexion angles to engage the trochlea. An abnormally high patella may therefore insufficiently engage the proximal trochlea groove both in extension and in the early phase of knee flexion - making it one of the potential risk factors for patellar instability. Accordingly, patella alta is present in 30% of patients with recurrent patellar dislocation.