The Sinding-Larsen Johansson syndrome ^1,2 and Osgood Schlatter disorder are osteochondroses of the inferior pole of the patella and the tibial tuberosity respectively. They are associated with activities like running, hiking. They can occur simultaneously as in this case.

The main differential diagnosis of Sinding-Larsen Johansson syndrome is patellar sleeve fracture ³. To rule it out, 3 elements:

1. There was no trauma, or acute presentation of pain. The evolution was progressive
2. On X rays ⁴:

• the osteochondrosis ossicle has a rounded and corticated edge (whereas the edges of a sleeve fracture are angulated with no cortication)
• a sleeve fracture generally has a crescentic appearance of a cat's claw, not seen in this case

3. An MRI was performed (not shown) revealed edema and joint effusion. There was no articular cartilage separation of sleeve fractures