title: Relationship of ACL Injury and Posterior Tibial Slope With Patient Age, Sex, and Race.
abstract: BACKGROUND
  Posterior tibial slope (PTS) has been proposed as a potential risk factor for anterior cruciate ligament (ACL) injury; however, studies that have examined this relationship have provided inconclusive and sometimes contradictory results. Further characterization of this relationship may enable the medical community to identify individuals at greater risk for ACL injury and possibly characterize an anatomic target during surgical reconstruction.
  
  
  OBJECTIVE
  The primary goal was to investigate the relationship between PTS and ACL injury. The secondary goal was to determine whether there are any patient factors, such as age, race, or sex, that correlate with ACL injury and PTS.
  
  
  METHODS
  Cross-sectional study; Level of evidence, 3.
  
  
  METHODS
  Medical records of 221 patients who underwent magnetic resonance imaging (MRI) of the knee between January 2003 and December 2009 were reviewed. Patients were separated into 2 groups: a study group of those subjects who had undergone surgery for ACL injury (n = 107) and a control group of patients diagnosed with patellofemoral syndrome (n = 114). Demographic data were collected, and MRI images from both groups were analyzed using imaging software to obtain medial and lateral tibial slope measurements. Data were then analyzed using analysis of variance (ANOVA) comparison and a multivariable regression model to determine which, if any, patient factors were related to probability of having an ACL injury.
  
  
  RESULTS
  ANOVA comparison demonstrated that the study group had significantly greater values for lateral PTS (6° ± 4°;P< .001) and medial PTS (7° ± 4°;P= .002) compared with controls (5° ± 3° and 5° ± 4°, respectively). After stepwise elimination of nonsignificant variables, the final multivariable logistic regression model determined that age (odds ratio [OR], 0.94;P< .001) and lateral PTS (OR, 1.12;P= .002) had statistically significant relationships with ACL injury. Medial PTS, race, and sex were not demonstrated to be significant predictors of ACL injury in this final model.
  
  
  CONCLUSIONS
  This study demonstrates a relationship between increased lateral PTS and ACL injury, which corroborates the findings of previously published studies. The findings presented in this article may help identify patients who are at greater risk of ACL injury and could potentially benefit from treatments aimed at modification of PTS.
authors.affiliation: David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Alana
authors.initials: A
authors.lastname: Waiwaiole
authors.affiliation: David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Ajay
authors.initials: A
authors.lastname: Gurbani
authors.affiliation: David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Kambiz
authors.initials: K
authors.lastname: Motamedi
authors.affiliation: David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Leanne
authors.initials: L
authors.lastname: Seeger
authors.affiliation: UCLA Department of Medicine Statistics, Los Angeles, California, USA.
authors.forename: Myung Shin
authors.initials: MS
authors.lastname: Sim
authors.affiliation: David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Nwajuaku
authors.affiliation: David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Hame
keywords: ACL injury; age; posterior tibial slope; race; sex