title: Is posterior tibial slope associated with noncontact anterior cruciate ligament injury?
abstract: OBJECTIVE
  This study aimed to: (1) examine whether the association between posterior tibial slope and noncontact ACL injury exists in Chinese population; (2) compare the reliability and consistency of the three methods (longitudinal axis, posterior and anterior tibial cortex axis) in lateral radiograph.
  
  
  METHODS
  Case-control study contained 146 patients in total (73 noncontact ACL injuries and 73 meniscus injuries, matched for age and gender), which were verified by arthroscopy, MRI and physical examination.
  
  
  RESULTS
  For the total population and the male subgroup, the mean posterior tibial slope of the ACL-injured group was significantly higher than that of the control group (P < 0.001). In addition, the longitudinal axis method exhibited the highest inter-rater (0.898) and intrarater reliability (0.928), whereas the anterior tibial cortex was the most variable (inter-rater reliability, 0.805; intrarater reliability, 0.824). The anterior tibial cortex method produced largest posterior tibial slope measurements (13.8 ± 3.3 for injury group; 11.6 ± 2.7 for control group), while the posterior tibial cortex method was the smallest (9.1 ± 3.1 for injury group; 7.2 ± 2.6 for control group). All three methods were not affected by age, sex, height, weight and BMI (n.s.).
  
  
  CONCLUSIONS
  The results of this study suggested that an increased posterior tibial slope was associated with the risk of noncontact ACL injury in Chinese population. Meanwhile, the longitudinal axis method is recommended for measuring posterior tibial slope in lateral radiograph in future studies. Posterior tibial slope measured by longitudinal axis method may be used as predictor of ACL injury.
  
  
  METHODS
  Case-control study, Level III.
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan Province, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zeng
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan Province, China.
authors.forename: Tuo
authors.initials: T
authors.lastname: Yang
authors.affiliation: Department of Orthopaedics, Third-Xiangya Hospital, Central South University, Changsha, Hunan Province, China.
authors.forename: Song
authors.initials: S
authors.lastname: Wu
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan Province, China.
authors.forename: Shu-guang
authors.initials: SG
authors.lastname: Gao
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan Province, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan Province, China.
authors.forename: Zhen-han
authors.initials: ZH
authors.lastname: Deng
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan Province, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan Province, China. lgh9640@sina.cn.
authors.forename: Guang-hua
authors.initials: GH
authors.lastname: Lei
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D044466:Asian People; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D013977:Tibia / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D000070600:Tibial Meniscus Injuries; D055815:Young Adult
keywords: Anterior cruciate ligament; Meta-analysis; Risk factor; Tibial slope