DOS 2018

150 · DOS Abstracts Increased TTTG measured on axial MRI is not due to lateralization of the tibial tubercle but medialization of the trochlear groove. A cross sectional study of dysplastic and non-dysplastic knees. Mathias Paiva, Lars Blønd, Kristoffer Weisskirchner Barfod Sports Orthopedic Research Center Copenhagen (SORC-C), Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre.; Department of Orthopedic Surgery, Zealand University Hospital, Køge and Aleris-Hamlet Parken Purpose / Aim of Study: To investigate if increased Tibial tubercle – Trochlear Groove distance (TT-TG) measured on axial MRI is due to lateralization of the tibial tubercle or medialization of the trochlear groove. Materials and Methods: The study was performed as a cross sectional study of 67 knees (29 normal, 26 with trochlear dysplasia (TD) and 12 with pa- tellar dislocation without TD). MRI data was gathered from October 2010 to December 2017 at Køge Hospital and Parken Private hospital. The medial bor- der of the posterior cruciate ligament (PCL) was chosen as the central anatomi- cal landmark. The distance from the tibial tubercle (TT) to PCL (TT-PCL) was measured to examine the lateralization of the tibial tubercle. The distance from the trochlear groove to PCL (TG-PCL) was measured to examine the medializa- tion of the trochlear groove. Between group differences was investigated by use of one-way ANOVA. Findings / Results: The mean (SD) values for TT-TG were 8.5 mm (3.6) in the normal group, 11.4 mm (6.2) in the group with patellar dislocation without TD and 17.1 mm (4.8) in the TD group (p<0.01). The mean (SD) values for TT- PCL were 19.5 mm (4.2) in the normal group, 17.0 mm (5.0) in the group with patellar dislocation without TD and 20.2 mm (5.0) in the TD group (p= 0.10). The mean (SD) values for TG-PCL were 10.5 mm (3.7) in the normal group, 5.8 mm (4.9) in the patellar dislocation group without TD and 3.9 mm (3.9) in the dysplastic group (p<0.01). Conclusions: TD knees had increased TT-TG compared to normal knees and knees with patellar dislocation without TD. The TT-PCL distance did not dif- fer significantly between groups, whereas the TG-PCL distance declined with increased TT-TG. The present results indicate that increased TT-TG is due to medialization of the trochlear groove and not lateralization of the tibial tubercle. 91.