Originally described by Norwegian physician Christian Magnus Falsen Sind-ing-Larsen and Swedish surgeon Sven Christian Johansson, Sinding-Larsen-Johansson syndrome (SLJS) is defined as ''apophysitis of the distal pole of the patella'' and is considered one of the osteochondroses . This condition of the distal patella and proximal patellar tendon is quite similar to Osgood-Schlatter disease and primarily affects athletically active adolescents between 10 and 14 years of age with prevalence in boys. This entity typically presents as pain and tenderness with occasional swelling over the inferior pole of the patella brought on by overuse or trauma .
Contusion or tendinopathy of the proximal patellar tendon creates a traction phenomenon followed by calcification and ossification, and patellar fracture or
Box 1: Differential Considerations for AKP
Patellar tendon causes
• Patello femoral OA
• Stress fracture
• Bipartite patella
Intraarticular pathology/Hoffa's fat pad
• Meniscal tear/cysts
• Plica syndromes
• Hoffa's syndrome
• Pes ancerine avulsion can produce one or multiple ossification sites. SLJS is most likely to occur in an active adolescent during ''growth spurts'' when the tendon cannot keep pace with the growing tibia, resulting in a relative shortening and traction on the immature lower pole of the patella. The natural duration of the disease is 3 to 12 months and usually requires only rest and conservative management .
Radiographs of the knee are frequently normal with varying calcification and ossification of the lower pole of the patella. Findings of osseous fragmentation of the inferior patella on knee radiography support the diagnosis in a patient with history and physical examination suggestive of SLJS (Fig. 2) .
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