The association of tibial slope and anterior cruciate ligament rupture in skeletally immature patients.

Abstract

The purpose of our study was to investigate the relation between posterior tibial slope and anterior cruciate ligament (ACL) rupture in patients with open physes. A retrospective case-control study was performed comparing skeletally immature patients with an ACL rupture with an age-matched control group. Posterior tibial slope was measured on plain lateral radiographs in both groups by blinded readers, at 2 separate time intervals, using a previously examined and accepted technique. Thirty-two patients were included in the study group (mean age, 13 years; age range, 9 to 17 years) and compared with 32 patients in the control group (mean age, 13 years; age range, 9 to 16 years). The mean posterior tibial slope in the ACL-injured population was 10.0° ± 3° versus 8.5° ± 3° in the control group (P = .0128). Statistical significance was seen in comparisons of slope measurements between the ACL-injured and control groups for 2 of the 3 readers (readers 1 and 3) at both time points (P = .0348 and P = .0051 for reader 1 and P = .0009 and P = .0059 for reader 3). Intrarater reliability proved superior with values correlating with moderate to good reliability, whereas inter-rater reliability values corresponded with fair to moderate reliability. The average posterior tibial slope was 9.5° (range, 3° to 14°) for female patients and 9.8° (range, 2° to 16°) for male patients. On the basis of the results of this study, the data support the notion that a moderate association may exist between an increased posterior tibial slope and ACL injury in pediatric patients with open physes. Level III, case-control study.