title: Mobile- versus fixed-bearing modern total knee replacements- which is the more patella-friendly design?: The 11-year New Zealand Joint Registry study.
abstract: OBJECTIVE
  Our study aimed to examine if a mobile-bearing total knee replacement (TKR) offered an advantage over fixed-bearing designs with respect to rates of secondary resurfacing of the patella in knees in which it was initially left unresurfaced.
  
  
  METHODS
  We examined the 11-year report of the New Zealand Joint Registry and identified all primary TKR designs that had been implanted in > 500 knees without primary resurfacing of the patella. We examined how many of these were mobile-bearing, fixed-bearing cruciate-retaining and fixed-bearing posterior-stabilised designs. We assessed the rates of secondary resurfacing of the patella for each group and constructed Kaplan-Meier survival curves.
  
  
  RESULTS
  Our study showed a significantly higher rate of revision for secondary resurfacing of the patella in the fixed-bearing posterior-stabilised TKR designs compared with either fixed-bearing cruciate-retaining or mobile-bearing designs (p = 0.001 and p = 0.036, respectively).
  
  
  CONCLUSIONS
  This New Zealand Registry study shows that during the last 11 years, revision procedures to resurface an unresurfaced patella in primary TKR occurred at a higher rate in fixed-bearing posterior-stabilised designs.
authors.affiliation: Wellington Regional Hospital, OrthopaedicDepartment, Riddiford Street, Newtown, Wellington6021, New Zealand.
authors.forename: M C
authors.initials: MC
authors.lastname: Wyatt
authors.forename: C
authors.initials: C
authors.lastname: Frampton
authors.forename: J G
authors.initials: JG
authors.lastname: Horne
authors.forename: P
authors.initials: P
authors.lastname: Devane
keywords: Anterior knee pain; Knee revision; Patella pain; Patellar resurfacing; Total knee replacement