title: Joint line changes in cruciate-retaining versus posterior-stabilized computer-navigated total knee arthroplasty.
abstract: BACKGROUND
  This study compared joint line changes and functional outcomes between cruciate-retaining (CR) and posterior-stabilized (PS) computer-navigated total knee arthroplasties (TKAs). With the increased precision offered by computer navigation, we hypothesized that there should be minimal differences in the joint line changes between the groups and thus no significant differences in the clinical outcomes.
  
  
  METHODS
  A retrospective study of 195 patients with a minimum of 2-year follow-up following primary surgery was conducted. The patients were stratified into two groups: the CR group and the PS group. The joint line changes of both groups were then compared using the Student t test. Multivariate analysis and regression modelling were then utilized to analyze the functional outcomes of both groups.
  
  
  RESULTS
  CR knees had a significantly lesser mean joint line change of 1.70 mm as compared to 2.34 mm in PS knees (p = .04) but the absolute difference was only 0.64 mm. The PS group had significantly better final range of motion of 122° (±9.9°) as compared to 114° (±15.0°) in the CR group (p < .0001). There were no significant differences in the final outcome scores.
  
  
  CONCLUSIONS
  Although there is a significant difference statistically in the joint line changes between the groups, this difference is less than 1 mm and probably has no significant clinical impact. This is further affirmed by the fact that there was no significant difference in the clinical outcomes. The increased range seen in PS knees is probably not related to joint line changes.
  
  
  METHODS
  III.
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore, 169608, Singapore. hamidrazak@gmail.com
authors.forename: Hamid Rahmatullah
authors.initials: HR
authors.lastname: Bin Abd Razak
authors.forename: Hee Nee
authors.initials: HN
authors.lastname: Pang
authors.forename: Seng Jin
authors.initials: SJ
authors.lastname: Yeo
authors.forename: Mann Hong
authors.initials: MH
authors.lastname: Tan
authors.forename: Ngai Nung
authors.initials: NN
authors.lastname: Lo
authors.forename: Hwei Chi
authors.initials: HC
authors.lastname: Chong
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology* / Q000503:physiopathology; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D016119:Posterior Cruciate Ligament / Q000601:surgery*; D016059:Range of Motion, Articular; D025321:Surgery, Computer-Assisted