title: Oversizing the tibial component in TKAs: incidence, consequences and risk factors.
abstract: OBJECTIVE
  The incidence of anteroposterior overhang of the tibial component after TKA and its effect on clinical outcome were investigated, and the morphometric characteristics of the knees in which tibial baseplates were oversized were identified.
  
  
  METHODS
  One hundred and fourteen consecutive TKAs were retrospectively assessed. The dimensions of the tibia were measured on a pre-operative CT scan and were compared with those of the implanted tibial component. We analysed the effect of anteroposterior and mediolateral size variations on clinical outcomes 1 year after surgery.
  
  
  RESULTS
  An anteroposterior overhang was observed in 87 % of cases on the lateral plateau, in 88 % on the central plateau and in 25 % on the medial tibial plateau. The mean post-pre-operative size differences were 3.2 ± 2.7, 2.8 ± 2.7 and -1.6 ± 2.3 mm, respectively. (Positive value means oversizing). A mediolateral overhang of the tibial component was found in 61 % of the patients. Oversizing was significantly greater and more frequent in females. Patients oversized in the anteroposterior dimension had lower post-operative pain scores. Patients with mediolateral oversizing had decreased flexion 1 year after surgery. Anteroposterior oversizing was observed more frequently in patients with asymmetric tibial plateaus, while mediolateral oversizing was observed more frequently in patients with small tibias.
  
  
  CONCLUSIONS
  This study demonstrates that the incidence of oversized tibial plateau components is surprisingly high and that functional outcomes are lower in the case of mediolateral or anteroposterior oversizing. The risk of oversizing could be predicted as it occurs predominantly in patients with asymmetric proximal tibia and/or small tibia.
  
  
  METHODS
  IV.
authors.affiliation: Centre Orthopédique Santy, 24 Avenue Paul Santy, 69008, Lyon, France. bonnin.michel@gmail.com.
authors.forename: Michel P
authors.initials: MP
authors.lastname: Bonnin
authors.affiliation: Accelerate Innovation Management, 1 rue de la navigation, 1201, Geneva, Switzerland.
authors.forename: Mo
authors.initials: M
authors.lastname: Saffarini
authors.affiliation: Centre Orthopédique Santy, 24 Avenue Paul Santy, 69008, Lyon, France.
authors.forename: David
authors.initials: D
authors.lastname: Shepherd
authors.affiliation: Service de Biostatistique, Hospices Civils de Lyon, 69424, Lyon, France.|Université Lyon I, 69622, Villeurbanne, France.|CNRS, UMR 5558, Laboratoire Biostatistique Santé, 69495, Pierre-Bénite, France.
authors.forename: Nadine
authors.initials: N
authors.lastname: Bossard
authors.affiliation: Service de Biostatistique, Hospices Civils de Lyon, 69424, Lyon, France.|Université Lyon I, 69622, Villeurbanne, France.|CNRS, UMR 5558, Laboratoire Biostatistique Santé, 69495, Pierre-Bénite, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Dantony
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D015994:Incidence; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D009929:Organ Size; D020370:Osteoarthritis, Knee / Q000601:surgery*; D010149:Postoperative Pain / Q000453:epidemiology* / Q000503:physiopathology; D011184:Postoperative Period; D017755:Prosthesis Fitting; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D013977:Tibia / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed
keywords: Knee flexion; Oversizing; Pain; Tibial component; Total knee arthroplasty