Summary Sinding-Larson-Johansson (SLJ) syndrome is an overuse injury seen in adolescents leading to anterior knee pain at the inferior pole of patella at the proximal patella tendon attachment. Diagnosis is made clinically with tenderness over the inferior pole of the patella and radiographs of the knee may show a spur at the inferior pole of the patella. Treatment is nonoperative with NSAIDs, activity modifications and physical therapy with most cases resolving over time. Epidemiology Demographics more common in adolescence Location patellar tendon insertion at the inferior pole of the patella Etiology Pathophysiology chronic injury similar pathogenesis to Osgood-Schlatter similar to Osgood-Schlatter disease which is at the distal attachment of the patella tendon overuse causes a traction apophysitis Classification Blazina Classification Stage 1 Pain occurs after activity Stage 2 Pain present while performing activity and persists after activity Stage 3 Pain affecting/limiting function during activity Presentation History insidious onset of pain on anterior aspect of knee after or during activity Physical exam tenderness over inferior patella swelling Imaging Radiographs recommended views AP and lateral of knee findings may be normal may show spur at inferior pole of patella MRI indications if diagnosis unclear views inflammation best seen on T2 sagitals bony spurs best seen on T1 sagitals Treatment Nonoperative activity modifications, NSAIDS, physical therapy indications mainstay of treatment usually a self limiting process Operative debridement of damaged tissue/stimulation of healing response in some cases refractory to nonoperative treatment