title: Kinematics of a bicruciate-retaining total knee arthroplasty.
abstract: OBJECTIVE
  The recently reintroduced bicruciate-retaining Total Knee Arthroplasty (BCR TKA) is an interesting approach in the quest for close replication of knee joint biomechanics and kinematics closer to the native knee. Therefore, this study aimed at providing a detailed biomechanical view on the functional resemblance of BCR TKA to the native knee joint.
  
  
  METHODS
  Seven fresh-frozen full leg cadaver specimens (76 ± 10 year) were mounted in a 6 degrees-of-freedom kinematic rig that applied a dynamic squatting motion knee flexion. Two motion patterns were performed pre- and post-implantation of a fixed bearing BCR TKA: passive flexion-extension and squatting while an infrared camera system tracked the location of reflective markers attached to the tibia and femur. Additionally, specimen laxity was assessed using Lachman tests and varus/valgus stress tests in triplicate.
  
  
  RESULTS
  Overall, differences in tibiofemoral kinematics between native knee and BCR TKA were small. Some minor differences appeared under the load of a squat: less internal tibial rotation and some minor paradoxical anterior translation of the medial femoral condyle during mid-flexion. BCR TKA may slightly elevate the joint line. Knee laxity as measured by the Lachman and varus/valgus tests was not significantly influenced by BCR TKA implantation.
  
  
  CONCLUSIONS
  As both cruciate ligaments are preserved with BCR TKA the unloaded knee closely resembles native knee kinematics including preserving the rollback mechanism. The loss of the conforming anatomy of menisci and tibial cartilage and replacement via a relatively flat polyethylene inlay may account for the loss of tibial internal rotation and the slight paradoxical AP motion of the medial femoral condyle with BCR TKA. This phenomenon reproduces findings made earlier with fixed bearing unicondylar knee arthroplasty.
authors.affiliation: Center of Orthopedics and Trauma Surgery, University Hospital Marburg, Baldingerstrasse, 35043, Marburg, Germany. heyse@med.uni-marburg.de.
authors.forename: Thomas J
authors.identifier: http://orcid.org/0000-0003-3142-9574
authors.initials: TJ
authors.lastname: Heyse
authors.affiliation: Department of Orthopaedics, Katholieke Universiteit Leuven, Campus Pellenberg, Louvain, Belgium.
authors.forename: Joshua
authors.initials: J
authors.lastname: Slane
authors.affiliation: ZNA Stuivenberg, Antwerp, Belgium.
authors.forename: Geert
authors.initials: G
authors.lastname: Peersman
authors.affiliation: ZNA Stuivenberg, Antwerp, Belgium.
authors.forename: Margo
authors.initials: M
authors.lastname: Dirckx
authors.affiliation: ZNA Stuivenberg, Antwerp, Belgium.
authors.forename: Arne
authors.initials: A
authors.lastname: van de Vyver
authors.affiliation: Center of Orthopedics and Trauma Surgery, University Hospital Marburg, Baldingerstrasse, 35043, Marburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Dworschak
authors.affiliation: Center of Orthopedics and Trauma Surgery, University Hospital Marburg, Baldingerstrasse, 35043, Marburg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Fuchs-Winkelmann
authors.affiliation: Department of Orthopaedics, Katholieke Universiteit Leuven, Campus Pellenberg, Louvain, Belgium.
authors.forename: Lennart
authors.initials: L
authors.lastname: Scheys
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005269:Femur / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D008297:Male; D020370:Osteoarthritis, Knee / Q000503:physiopathology / Q000601:surgery; D010808:Physical Examination; D020959:Polyethylene; D016059:Range of Motion, Articular; D012399:Rotation; D013977:Tibia / Q000601:surgery
chemical_list: D020959:Polyethylene
keywords: BCR TKA; Kinematics; Knee; XP