title: Increased lateral tibial slope predicts high-grade rotatory knee laxity pre-operatively in ACL reconstruction.
abstract: OBJECTIVE
  To determine the influence of anatomical features of both the tibia and femur on quantitative pivot shift of anterior cruciate ligament (ACL)-injured patients.
  
  
  METHODS
  Fifty-three consecutive ACL-injured patients (mean age 26 ± 10.1 years, 36 males) who underwent ACL reconstruction were prospectively enrolled. Two blinded observers measured the parameters of medial and lateral tibial slope, femoral condyle width, notch width, bicondylar width and tibial plateau width on magnetic resonance imaging. The same examiner performed pivot shift under anaesthesia, while a previously validated image analysis technique was used to quantify knee kinematics during examination. The median lateral compartment translation detected during pivot shift testing (2.8 mm) was used to classify patients into "low-grade rotatory laxity" (≤2.8 mm) and "high-grade rotatory laxity" (>2.8 mm) groups.
  
  
  RESULTS
  Twenty-nine subjects were grouped as "low-grade rotatory laxity", and 24 subjects were grouped as "high-grade rotatory laxity". Of the tested bone morphologic parameters, lateral tibial plateau slope was significantly greater in "high-grade rotatory laxity" group (9.3° ± 3.4°) compared to "low-grade rotatory laxity" group (6.1° ± 3.7°) (p < 0.05). Lateral tibial plateau slope was a significant predictor of "high-grade rotatory laxity" (odds ratio 1.27, p < 0.05). A tibial slope of 9° and greater predicted "high-grade rotatory laxity" (sensitivity 63 %; specificity 72 %).
  
  
  CONCLUSIONS
  Increased slope of the lateral tibial plateau might be an important anatomical variable predicting high-grade rotatory laxity in patients with ACL injury. The finding can be useful in the clinical setting in predicting potential non-copers to conservative therapy and aid in the individualization of the reconstructive procedures of patients.
  
  
  METHODS
  Prospective diagnostic study, Level II.
authors.affiliation: Department of Orthopaedic Surgery, Center for Sports Medicine, University of Pittsburgh, 3200 S Water Street, Pittsburgh, PA, 15203, USA.|Orthopaedic Robotics Laboratory, Departments of Orthopaedic Surgery and Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Ata A
authors.initials: AA
authors.lastname: Rahnemai-Azar
authors.affiliation: Department of Orthopaedic Surgery, Center for Sports Medicine, University of Pittsburgh, 3200 S Water Street, Pittsburgh, PA, 15203, USA.
authors.forename: Ermias S
authors.initials: ES
authors.lastname: Abebe
authors.affiliation: Department of Orthopaedic Surgery, Center for Sports Medicine, University of Pittsburgh, 3200 S Water Street, Pittsburgh, PA, 15203, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Johnson
authors.affiliation: Department of Orthopaedic Surgery, Center for Sports Medicine, University of Pittsburgh, 3200 S Water Street, Pittsburgh, PA, 15203, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Labrum
authors.affiliation: Department of Orthopaedic Surgery, Center for Sports Medicine, University of Pittsburgh, 3200 S Water Street, Pittsburgh, PA, 15203, USA.
authors.forename: Freddie H
authors.initials: FH
authors.lastname: Fu
authors.affiliation: Department of Orthopaedic Surgery, Center for Sports Medicine, University of Pittsburgh, 3200 S Water Street, Pittsburgh, PA, 15203, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Irrgang
authors.affiliation: Department of Orthopedic Surgery, Sahlgrenska University Hospital, Göteborg, Sweden.
authors.forename: Kristian
authors.initials: K
authors.lastname: Samuelsson
authors.affiliation: Department of Orthopaedic Surgery, Center for Sports Medicine, University of Pittsburgh, 3200 S Water Street, Pittsburgh, PA, 15203, USA. musahlv@upmc.edu.|Orthopaedic Robotics Laboratory, Departments of Orthopaedic Surgery and Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA. musahlv@upmc.edu.
authors.forename: Volker
authors.initials: V
authors.lastname: Musahl
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries / Q000503:physiopathology*; D059549:Anterior Cruciate Ligament Reconstruction; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000503:physiopathology; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D057234:Preoperative Period; D011446:Prospective Studies; D012399:Rotation
keywords: ACL; Anterior cruciate ligament; Bone morphology; Pivot shift; Rotatory laxity; Tibial plateau slope