Tibial tuberosity-trochlear groove (TT-TG) distance is a measure of lateralization of the tibial tuberosity in relation

measure of lateralization of the tibial tuberosity in relation to femoral trochlea. Many studies have confirmed that lateralization of the tuberosity is linked to patellar instability, thus TT-TG is an important parameter for evaluation of patellofemoral disorders. However, the degree of lateralization that may contribute to actual dislocation varies among studies. Alemparte et al. studied healthy volunteers and found that normal values for TT-TG were 13.6 ± 8.8 mm, indicative of large variation. Dejour et al. reported that the TT-TG in the control group was 12.7 ± 3.4 mm and > 20 mm in pathological cases. Thus, there is reportedly a high degree of variability in the normal TT-TG values and furthermore, some methods of measurement are complicated with significant intraand interobserver measurement errors. Anterior knee pain is a common finding in young adults with no definite etiology or diagnostic test. PatelRadiologic Measurement of Tibial Tuberosity-Trochlear Groove (TT-TG) Distance by Lower Extremity Rotational Profile Computed Tomography in Koreans