title: MRI Anatomy of the Tibial ACL Attachment and Proximal Epiphysis in a Large Population of Skeletally Immature Knees: Reference Parameters for Planning Anatomic Physeal-Sparing ACL Reconstruction.
abstract: BACKGROUND
  To aid in performing anatomic physeal-sparing anterior cruciate ligament (ACL) reconstruction, it is important for surgeons to have reference data for the native ACL attachment positions and epiphyseal anatomy in skeletally immature knees.
  
  
  OBJECTIVE
  To characterize anatomic parameters of the ACL tibial insertion and proximal tibial epiphysis at magnetic resonance imaging (MRI) in a large population of skeletally immature knees.
  
  
  METHODS
  Cross-sectional study; Level of evidence, 3.
  
  
  METHODS
  The ACL tibial attachment site and proximal epiphysis were examined in 570 skeletally immature knees with an intact ACL (age, 6-15 years) using 1.5-T proton density-weighted sagittal MRI; also measured were the tibial anteroposterior diameter; anterior, central, and posterior ACL attachment positions; vertical height of the epiphysis; and maximum oblique epiphyseal depth extending from the ACL tibial attachment center to the tibial tuberosity.
  
  
  RESULTS
  In adolescents (11-15 years of age), the center of the ACL's tibial attachment was 51.5% ± 5.7% of the anteroposterior diameter of the tibia, with no significant differences between sexes or age groups (P > .05 in all cases). Mean vertical epiphyseal height was 15.9 ± 1.7 mm in the adolescent group, with significant differences between 11-year-olds (15.2 ± 1.5 mm) and 15-year-olds (16.6 ± 1.6 mm), P < .001, and between males (16.6 ± 1.5 mm) and females (14.8 ± 1.4), P < .001. Mean maximum oblique depth was 30.0 ± 5.3 mm, with a significant difference between 11-year-olds (26.7 ± 4.9 mm) and 15-year-olds (32.7 ± 5.1 mm), P < .001, and between males (29.7 ± 6.4 mm) and females (27.8 ± 5.2 mm), P < .001. The maximum oblique depth occurred at a mean angle of ~50°, and this angle did not change with age or sex. There was a significant moderate correlation (r = 0.39, P < .001) between epiphyseal vertical height and maximum oblique depth.
  
  
  CONCLUSIONS
  The center of the ACL tibial attachment was consistently near 51% of the anteroposterior diameter, regardless of age or sex. The vertical depth of the tibial epiphysis was ~16 mm in adolescents. Maximum oblique depth from ACL attachment was ~30 mm, occurring at a mean angle ~50° regardless of age or sex. The normative values for tibial ACL attachment and epiphyseal anatomy presented here may be helpful in selecting candidates for surgery and in planning surgical approaches for pediatric ACL reconstruction.
authors.affiliation: Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Canada.
authors.forename: Vimarsha Gopal
authors.initials: VG
authors.lastname: Swami
authors.affiliation: Departmental of Biomedical Engineering, University of Alberta, Edmonton, Canada.
authors.forename: Myles
authors.initials: M
authors.lastname: Mabee
authors.affiliation: Department of Surgery, Division of Orthopedic Surgery, University of Alberta, Edmonton, Canada.
authors.forename: Catherine
authors.initials: C
authors.lastname: Hui
authors.affiliation: Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Canada jjaremko@ualberta.ca.
authors.forename: Jacob Lester
authors.initials: JL
authors.lastname: Jaremko
mesh_terms: D000293:Adolescent; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology* / Q000254:growth & development; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D002648:Child; D003430:Cross-Sectional Studies; D004838:Epiphyses / Q000033:anatomy & histology; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000254:growth & development; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology* / Q000254:growth & development; D008279:Magnetic Resonance Imaging; D008297:Male; D012016:Reference Values; D013977:Tibia / Q000033:anatomy & histology / Q000254:growth & development
keywords: anatomy; anterior cruciate ligament reconstruction; magnetic resonance imaging; pediatric; physeal-sparing reconstruction