title: Tibial component designs in primary total knee arthroplasty: should we reconsider all-polyethylene component?
abstract: OBJECTIVE
  Despite the frequency with which total knee arthroplasties (TKAs) are performed, whether they are best performed using all-polyethylene or metal-backed tibial components remains a controversy. The aim of the present study was to determine the advantages and disadvantages of metal-backed compared with all-polyethylene tibial components during TKAs through an evaluation of current literature.
  
  
  METHODS
  A meta-analysis and systematic review of randomized and non-randomized comparative studies comparing metal-backed with all-polyethylene tibial components during TKAs were performed. The focus of the analysis was on the outcomes of knee score, range of motion (ROM), quality of life, implant alignment, tibial migration, radiolucent line, complication, reoperation, and implant survivorship.
  
  
  RESULTS
  A total of 10 randomized/quasi-randomized controlled trials and 13 non-randomized comparative studies assessing 19,767 TKAs were eligible. On the basis of these studies, no significant differences were found between the 2 groups with regard to knee score, ROM, quality of life, complication, and reoperation. The findings indicated that using all-polyethylene tibial components is associated with lower continuous migration rate compared with metal-backed tibial components. Only 13 studies provided adequate data on implant survivorship during intermediate or long-term follow-up. Of these, 9 found that no statistical significance existed between the 2 groups. The other 3 studies found that using all-polyethylene components yielded a higher survival rate than using metal-backed components.
  
  
  CONCLUSIONS
  Metal-backed tibial components had no obvious advantages over all-polyethylene tibial components in TKAs. However, this finding should be interpreted with caution due to publication bias, low methodological quality of the included studies, and different surgical interventions.
  
  
  METHODS
  Therapeutic study (systematic review and meta-analysis), Level III.
authors.affiliation: Department of Orthopaedic Surgery, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University School of Medicine, 600 Yisan Road, Shanghai, 200233, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Cheng
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Pan
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Xianlong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008670:Metals; D020959:Polyethylene; D011474:Prosthesis Design / Q000295:instrumentation*; D017594:Publication Bias; D013977:Tibia
chemical_list: D008670:Metals; D020959:Polyethylene