Abstract
The infrapatellar fat pad is functionally deformed with joint movement and is involved in adjusting the internal pressure of the knee joint. On the other hand, it can also become a source of anterior knee pain due to inflammation and degeneration. A young female handball player experienced anterior knee pain. No obvious abnormality was observed on basic X-ray and magnetic resonance images. Dynamic observation using ultrasonic diagnostic imaging showed poor kinetics with infiltration of the infrapatellar fat pad into the patellar ligament and the tibial condyle, with the knee joint in extension on the affected side compared with the normal side. Knee joint range of movement (affected side vs. normal side) was restricted to 140° p / 150° flexion and extension - 10° p / 5°, and there was infrapatellar tenderness in the affected region. Patella baja was confirmed compared with the normal side. In addition, the flexibility of the infrapatellar fat pad was reduced. From these findings, it was inferred that the cause of pain was restriction of knee joint extension due to reduced flexibility of the infrapatellar fat pad. Treatment of the infrapatellar fat pad, joint range training exercises, and muscle strengthening training exercises were carried out. Pain and restricted range of joint movements improved and the patient could returned to competitive sports.
