11 year old girl with left knee pain and instability. Evaluate for patellar instability. Please calculate TT-TG distance. MENISCI: The medial and lateral menisci are intact.ARTICULAR CARTILAGE AND BONE: There is edema within the medial aspect of the patella, and to a lesser degree, within the lateral aspect of the lateral femoral condyle reflecting prior transient dislocation of the patella. There also appears to be a tiny avulsion fracture fragment which measures approximately 5 mm in greatest dimension along the medial aspect of the patella. The femoral trochlea is shallow, particularly superiorly where it is flattened indicating trochlear dysplasia. The TT-TG distance is 12, within normal limits. We see no fluid-filled articular cartilage defect.LIGAMENTS: The ACL and PCL are intact. EXTENSOR MECHANISM: The Insall-Salvati ratio is between 1.4 and 1.5 indicating patella alta. There is slight lateral patellar tilt. There is also edema within the soft tissues medial to the patella at the site of the small avulsion fracture. We cannot exclude injury to the patellar attachment of the medial patellofemoral ligament. ADDITIONAL
Patellar instability with femoral trochlear dysplasia and patella alta and bone contusions indicating prior transient dislocation of the patella. The TT-TG distance is normal.