title: Posterior tibial slope influences static anterior tibial translation in anterior cruciate ligament reconstruction: a minimum 2-year follow-up study.
abstract: BACKGROUND
  Posterior tibial slope (PTS) has recently been identified as a risk factor for anterior cruciate ligament (ACL) injuries because of an associated increase in anterior tibial translation (ATT) and ACL loading. However, few studies concerning the correlation between PTS and postoperative ATT have been published.
  
  
  OBJECTIVE
  To analyze the relationship between PTS and postoperative ATT in ACL reconstruction (ACLR).
  
  
  METHODS
  Case control study; Level of evidence, 3.
  
  
  METHODS
  Included in this retrospective study were 40 consecutive patients who underwent ACLR (28 male, 12 female; median age, 22 years; range, 14-44 years) from October 2010 to June 2011. The patients were divided into 3 groups based on medial and lateral PTS values as measured on MRI. Demographic data and results of the manual maximum side-to-side difference with a KT-1000 arthrometer at 30° of knee flexion before ACLR and at final follow-up were collected; results were divided into ATT ≤2 mm, 2 mm < ATT < 5 mm, and ATT ≥5 mm. First, the distribution of ATT in the 3 groups was compared, and then correlation analysis and logistic regression were conducted to determine the correlation between PTS and ATT. Finally, the thresholds of medial and lateral PTS were calculated.
  
  
  RESULTS
  Results of the ATT measurements were collected at a mean of 27.5 months (range, 24.0-37.0 months) after ACLR. The group with a PTS ≥5° had significantly more cases of ATT ≥5 mm than the group with a PTS <3° (medial PTS: P = .005; lateral PTS: P = .016). There were statistically significant correlations with ATT for both medial (r = 0.43, P = .005) and lateral (r = 0.36, P = .02) PTS. Medial or lateral PTS resulted in the increased probability of ATT ≥5 mm, with an odds ratio of 1.76 (P = .011) and 1.68 (P = .008), respectively. The threshold of an increased risk of ATT ≥5 mm was a medial PTS >5.6° (P = .003) or a lateral PTS >3.8° (P = .002).
  
  
  CONCLUSIONS
  There was a significant correlation between PTS and postoperative anterior knee static stability in this study. Patients with a steeper medial or lateral PTS showed a higher risk of ATT ≥5 mm at thresholds of 5.6° and 3.8°, respectively.
authors.affiliation: Hua Feng, Sports Medicine Service, Beijing Jishuitan Hospital, No. 31, Xin Jie Kou Dong Street, Xicheng District, Beijing, 100035, China. fenghua20080617@126.com.
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Hong
authors.forename: Hua
authors.initials: H
authors.lastname: Feng
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Guanyang
authors.initials: G
authors.lastname: Song
authors.forename: Xingzuo
authors.initials: X
authors.lastname: Chen
authors.forename: Hongwu
authors.initials: H
authors.lastname: Zhuo
mesh_terms: D000293:Adolescent; D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D007718:Knee Injuries / Q000601:surgery; D007719:Knee Joint / Q000033:anatomy & histology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D013709:Tendon Transfer / Q000379:methods; D013977:Tibia / Q000033:anatomy & histology* / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult
keywords: anterior cruciate ligament reconstruction; anterior tibial translation; correlation; lateral posterior slope; medial posterior tibial slope; risk factor