title: The angle of inclination of the native ACL in the coronal and sagittal planes.
abstract: OBJECTIVE
  The purpose of this cross-sectional study was to evaluate the angle of inclination of the native anterior cruciate ligament (ACL) in both the sagittal and coronal planes and to evaluate these findings based on sex, height, BMI, and skeletal maturity.
  
  
  METHODS
  Inclusion criteria for the study included patients undergoing routine magnetic resonance imaging (MRI) of the knee at a single outpatient orthopedic center who had an intact ACL on MRI. Measurements of the angle of inclination were made on MRIs in both the sagittal and coronal planes. Patients were compared based on sex, height, BMI, and skeletal maturity.
  
  
  RESULTS
  One-hundred and eighty-eight patients were included (36 skeletally immature/152 skeletally mature; 98 male/90 female). The overall angle of inclination was 74.3° ± 4.8° in the coronal plane and 46.9° ± 4.9° in the sagittal plane. Skeletally immature patients (coronal: 71.8° ± 6.1°; sagittal: 44.7° ± 5.5°) were significantly different in both coronal and sagittal planes (P = 0.04 and 0.01, respectively) from skeletally mature patients (coronal: 75.3° ± 4.7°; sagittal: 47.4° ± 4.7°). There were no differences based on sex, height, or BMI.
  
  
  CONCLUSIONS
  There are differences between the angle of inclination findings in this study and other studies, which could be due to MRI and measurement techniques. Clinically, skeletal maturity may be important to account for when using the ACL angle of inclination to evaluate anatomic ACL reconstruction.
  
  
  METHODS
  Prognostic retrospective study, Level of evidence III.
authors.affiliation: University of Minnesota Medical School, 420 Delaware Street SE, Minneapolis, MN, 55455, USA. reidx160@umn.edu.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Reid
authors.affiliation: TRIA Orthopaedic Center, 8100 Northland Drive, Bloomington, MN, 55431, USA.
authors.forename: Bret
authors.initials: B
authors.lastname: Yonke
authors.affiliation: University of Minnesota Medical School, 420 Delaware Street SE, Minneapolis, MN, 55455, USA.|TRIA Orthopaedic Center, 8100 Northland Drive, Bloomington, MN, 55431, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Tompkins
mesh_terms: D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies
keywords: ACL rupture; Coronal; Inclination angle; MRI; Native; Sagittal; Skeletally immature