Osgood-Schlatter disease (OSD) is a well-described clinical condition, although its origin remains controversial. Mechanical, growth or traumatic factors are suggested as causes of this lesion. Thirty-five patients were included in this study. Twenty of them had OSD (study group) and the remaining 15 adolescents constituted the control group. Magnetic resonance imaging of the knees was performed in all patients. The distance between the distal pole of the patella and the proximal margin of patellar tendon attachment to the tibial apophysis (A), the distance between the distal pole of the patella and the tibial tubercle epiphysis (B), the distance between the proximal margin of the patellar tendon attachment to the tibia and the tibial tubercle epiphysis (C) and the distance between the knee joint level and the tibial tubercle epiphysis (D) were measured. The ratio of the distance between the distal pole of the patella and the proximal margin of the patellar tendon attachment to the tibia to the distance between the distal pole of the patella and the tibial tubercle epiphysis (A : B) was lower in the study group. The ratio of the distance between the proximal margin of the patellar tendon attachment point to the tibia and the tibial tubercle epiphysis to the distance between the knee joint level and the tibial tubercle epiphysis (C : D) was higher in the control group. We conclude that if the patellar tendon attaches more proximally and in a broader area to the tibia, this might probably cause OSD.