Sy. Osgood Schlatter is juvenile osteochondrosis characterized by traction of the patellar tendon apophysis. The disease affects adolescents and children who are actively involved in sports. The incidence is more common in males than in females. Activities that increase the risk of developing symptoms and eventually the syndrome and disease are football, basketball, volleyball and other sports that require increased activity of the quadriceps femoris. In addition to physical examination and medical history, there are various techniques and tools for diagnosing this condition. Today, ultrasound is most often used thanks to reliable results, fine display of structures, ease of use and non-invasive nature. Ultrasound is followed by magnetic resonance imaging, then X-ray and then CT. The prognosis is good. Rehabilitation and treatment is almost always conservative. From 5 to 10% of patients are forced to undergo surgery. The modalities used in rehabilitation are few. Due to the nature of the syndrome, electrotherapy and magnetotherapy are contraindicated. In the acute phase, the principle of "PEACE and LOVE" is increasingly used today. The emphasis in the acute phase is "PEACE" where knee protection is introduced by reducing and changing activities. Reduction of physical activity is recommended for all patients. After the acute phase, the "LOVE" part of the principle is introduced, in which the muscle is strengthened and the knee function is restored, and the patient progressively returns to sports. The return to sport is strictly individual and depends on the subjective feeling of the patient, the condition of the knee, the level of pain and the emotional state of the patient.