title: Influence of mediolateral tibial baseplate position in TKA on knee kinematics and retropatellar pressure.
abstract: OBJECTIVE
  Anterior knee pain is a major reason for unsatisfied patients after total knee arthroplasty (TKA). Since malposition and increased retropatellar peak pressure are supposed to contribute to pain, we conducted this in vitro study to analyse the influence of mediolateral tibial component position on tibiofemoral and patella kinematics as well as retropatellar pressure.
  
  
  METHODS
  Eight fresh frozen cadaver specimens were tested after a fixed-bearing TKA. To evaluate the influence of mediolateral tibial component position, special inlays with 3 mm of medialization and lateralization were constructed. For the analysis, a weight-bearing knee rig under a loaded squat from 20° to 120° of flexion was used. Tibiofemoral and patella kinematics were measured with an ultrasonic-based three-dimensional motion analysis system. Additionally, retropatellar pressure distribution was registered with a pressure-sensitive film.
  
  
  RESULTS
  Alteration of mediolateral tibial component position by 3 mm did not reveal a significant influence on retropatellar peak pressure (7.5 ± 2.5 vs. 7.2 ± 2.6 MPa). Regarding tibiofemoral kinematics, 3-mm medialization of the tibial baseplate significantly increased lateral femoral rollback and femorotibial external rotation. Medialization of 3 mm also significantly increased the relative medial patella shift and decreased lateral patella tilt.
  
  
  CONCLUSIONS
  Medialization of the tibial baseplate came along with more lateral rollback and external femorotibial rotation. For the positioning of the tibial baseplate, rotational alignment seems to be more important than mediolateral orientation. Since retropatellar peak pressure remained rather unchanged, the tibial baseplate should be placed by the surgeon looking for a maximal tibial coverage without overhang.
authors.affiliation: Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany. arnd.steinbrueck@med.uni-muenchen.de.
authors.forename: Arnd
authors.initials: A
authors.lastname: Steinbrück
authors.affiliation: Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fottner
authors.affiliation: Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schröder
authors.affiliation: Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Woiczinski
authors.affiliation: Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Schmitt-Sody
authors.affiliation: Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Müller
authors.affiliation: Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Müller
authors.affiliation: Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany.
authors.forename: Volkmar
authors.initials: V
authors.lastname: Jansson
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 / Q000502:physiology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000502:physiology* / Q000601:surgery; D011312:Pressure; D016059:Range of Motion, Articular; D012399:Rotation; D013977:Tibia / Q000601:surgery; D016474:Weight-Bearing
keywords: Knee kinematics; Mediolateral malalignment; Retropatellar pressure; Tibial component; Total knee arthroplasty