Increased medial tibial slope in teenage pediatric population with open physes and anterior cruciate ligament injuries

PURPOSE: Variations in bony morphology have been associated with anterior cruciate ligament (ACL) injury risk. The primary aim of this study was to compare the tibial slope in the teenage pediatric population with open physes, with and without ACL injury. The secondary aims were to compare the notch width index (NWI) and determine the influence of gender and age on tibial slope and NWI. METHODS: Thirty-nine teenage pediatric subjects were included in this study, 16 with and 23 without ACL injury. Medial tibial slope and lateral tibial slope and NWI as measured on plain radiographs were compared between the groups using an independent t-test. Comparison of tibial slope and NWI was also performed between male and female subjects. Pearson correlation coefficient between age and tibial slope and NWI was calculated. RESULTS: The medial tibial slope averaged 10.2 (±3.9) degrees, the lateral tibial slope 11.5 (±3.9) degrees, and the NWI 0.26. There was a significant difference in medial tibial slope between the ACL-injured (12.1 degrees) subjects and the controls (8.9 degrees) (P = 0.009). There was no significant difference in lateral tibial slope or NWI between the groups. There was no significant difference in the medial tibial slope and lateral tibial slope and NWI between the male and female subjects. Subject age was not correlated with medial tibial slope and lateral tibial slope or NWI. CONCLUSION: There was an increased medial tibial slope in ACL-injured teenagers with open physes, when compared to a control group of teenager with open physes without ACL injury.