title: Tibial component considerations in bicruciate-retaining total knee arthroplasty: A 3D MRI evaluation of proximal tibial anatomy.
abstract: BACKGROUND
  Restoration of normal anatomy and proper ligament balance are theoretical prerequisites for reproducing physiological kinematics with bicruciate-retaining total knee arthroplasty (TKA). The purpose of this study was to use a 3D MRI technique to evaluate the topography of the proximal tibia and outline considerations in tibial component design for bicruciate-retaining TKA.
  
  
  METHODS
  We identified 100 consecutive patients (50 males and 50 females) between ages 20 and 40 years with knee MRIs without arthritis, dysplasia, ACL tears, or prior knee surgery. A novel 3D MRI protocol coordinating axial, coronal, and sagittal images was used to measure: 1) medial and lateral posterior tibial slopes; 2) medial and lateral coronal slopes; and 3) distance from the anterior tibia to the ACL footprint.
  
  
  RESULTS
  There was no overall difference in medial and lateral posterior tibial slopes (5.5° (95% CI 5.0 to 6.0°) vs. 5.4° (95% CI 4.8 to 6.0°), respectively (p=0.80)), but 41 patients had side-to-side differences greater than 3°. The medial coronal slope was greater than the lateral coronal slope (4.6° (95% CI 4.0 to 5.1°) vs. 3.3° (95% CI 2.9 to 3.7°), respectively (p<0.0001)). Females had less clearance between the anterior tibia and ACL footprint than males (10.8mm (95% CI 10.4 to 11.2mm) vs. 13.0mm (95% CI 12.5 to 13.5mm), respectively (p<0.0001)).
  
  
  CONCLUSIONS
  Due to highly variable proximal tibial topography, a monoblock bicruciate-retaining tibial baseplate may not reproduce normal anatomy in all patients.
  
  
  METHODS
  Level IV - Anatomic research study.
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, United States.
authors.forename: Vishal
authors.initials: V
authors.lastname: Saxena
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, United States.
authors.forename: Jason B
authors.initials: JB
authors.lastname: Anari
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Ruutiainen
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, United States.
authors.forename: Pramod B
authors.initials: PB
authors.lastname: Voleti
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, WI, United States.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Stephenson
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, United States. Electronic address: gwo-chin.lee@uphs.upenn.edu.
authors.forename: Gwo-Chin
authors.initials: GC
authors.lastname: Lee
mesh_terms: D000328:Adult; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D007720:Knee Prosthesis; D008279:Magnetic Resonance Imaging; D008297:Male; D011474:Prosthesis Design; D013977:Tibia / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000601:surgery; D055815:Young Adult
keywords: Bicruciate-retaining; MRI; TKA; Tibial slope