In clinical evaluation, what distinguishes a patellar sleeve fracture from Syndig-Larsen-Johansson syndrome?

A patellar sleeve fracture is commonly seen in adolescent athletes and is characterized by a fracture of the inferior pole of the patella with a true fracture involving the patellar tendon attached to it. In clinical evaluation, the presence of effusion (swelling due to fluid accumulation in the joint) and the inability to perform straight leg raises are key indicators that help differentiate this injury from Syndig-Larsen-Johansson syndrome.

Syndig-Larsen-Johansson syndrome, on the other hand, is a condition associated with chronic traction apophysitis at the inferior pole of the patella and typically does not lead to significant effusion in the joint. Patients with this syndrome may experience pain and tenderness but usually retain the ability to perform straight leg raises, as the damage is mainly related to irritation in the area rather than a fracture.

The distinction between these two conditions is critical; while both can cause knee pain in younger athletes, the presence of effusion and an inability to perform certain movements, such as straight leg raises, strongly suggests a more acute injury like a patellar sleeve fracture rather than the chronic overuse condition seen in Syndig-Larsen-Johansson syndrome. This clinical context underscores the importance of specific physical examination findings in