title: Anatomic tibial component design can increase tibial coverage and rotational alignment accuracy: a comparison of six contemporary designs.
abstract: OBJECTIVE
  The aim of this study was to comprehensively evaluate contemporary tibial component designs against global tibial anatomy. We hypothesized that anatomically designed tibial components offer increased morphological fit to the resected proximal tibia with increased alignment accuracy compared to symmetric and asymmetric designs.
  
  
  METHODS
  Using a multi-ethnic bone dataset, six contemporary tibial component designs were investigated, including anatomic, asymmetric, and symmetric design types. Investigations included (1) measurement of component conformity to the resected tibia using a comprehensive set of size and shape metrics; (2) assessment of component coverage on the resected tibia while ensuring clinically acceptable levels of rotation and overhang; and (3) evaluation of the incidence and severity of component downsizing due to adherence to rotational alignment and overhang requirements, and the associated compromise in tibial coverage. Differences in coverage were statistically compared across designs and ethnicities, as well as between placements with or without enforcement of proper rotational alignment.
  
  
  RESULTS
  Compared to non-anatomic designs investigated, the anatomic design exhibited better conformity to resected tibial morphology in size and shape, higher tibial coverage (92% compared to 85-87%), more cortical support (posteromedial region), lower incidence of downsizing (3% compared to 39-60%), and less compromise of tibial coverage (0.5% compared to 4-6%) when enforcing proper rotational alignment.
  
  
  CONCLUSIONS
  The anatomic design demonstrated meaningful increase in tibial coverage with accurate rotational alignment compared to symmetric and asymmetric designs, suggesting its potential for less intra-operative compromises and improved performance.
  
  
  METHODS
  III.
authors.affiliation: Zimmer, Inc., P.O. Box 708, Warsaw, IN, 46581-0708, USA, yifei.dai@zimmer.com.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Dai
authors.forename: Giles R
authors.initials: GR
authors.lastname: Scuderi
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Bischoff
authors.forename: Kim
authors.initials: K
authors.lastname: Bertin
authors.forename: Samih
authors.initials: S
authors.lastname: Tarabichi
authors.forename: Ashok
authors.initials: A
authors.lastname: Rajgopal
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D017760:Bone Malalignment / Q000517:prevention & control* / Q000601:surgery; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D012399:Rotation; D013977:Tibia / Q000033:anatomy & histology / Q000601:surgery*