Magnetic resonance imaging assessment of tibial tuberosity-trochlear groove distance: normal values for males and females

The aim of this study was to report normal values of the tibial tuberosity-trochlear groove distance (TTTG) in males and females and assess the reliability of MRI in measuring TTTG. Patients presenting with a suspected meniscus injury without any patellofemoral or ligamentous instability, and arthroscopically normal cruciate ligaments and patellofemoral joints were included in the study. K-PACSA (c) was used for MRI analysis and was performed by three observers blinded to each others' measurements. One hundred patients (57 males, 43 females) were recruited from 2006-2010. The mean TTTG in males was 9.91 mm (95% CI 8.9-10.8 mm) and in females 10.04 mm (95% CI 8.9-11.1). The coefficient of variation was < 10% for both intra and inter-observer analysis. The normal TTTG distance is 10 +/- A 1 mm with MRI being a reliable method of measurement. Literature supports a high degree of variability in reporting TTTG. This study establishes normal TTTG values, which will help in the assessment and treatment of patellofemoral disorders.