**3.2**

Patellofemoral synovial hyperplasia is a less well-described syndrome, characterized by a more diffuse proliferation of tissue proximal to the patella. Symptoms include pain and crepitus, most prominent during active knee extension from a 90° flexed position during stair climbing or rising from a chair. Knee range of motion (ROM) tends not to be affected and the lack of a discrete "clunk" is also criterion for this diagnosis.
