title: Effect of patellar thickness on early results of total knee replacement with patellar resurfacing.
abstract: OBJECTIVE
  Patellar thickness is a concern in total knee replacement with patellar resurfacing because of the risk of patellar fracture or implant loosening. The aim of this study was to evaluate if patellar thickness is related to clinical outcome in the absence of patellar fracture or implant loosening.
  
  
  METHODS
  Early results of 169 patients who underwent total knee replacement with patellar resurfacing were reviewed to assess the effect of patellar thickness on clinical outcome. The mean follow-up was 13 months. The range of motion, Knee Society Score, Function Score and WOMAC Score were assessed preoperatively, at day 0, 6 months and 1 year. Radiographs were assessed for patellar fracture or implant loosening.
  
  
  RESULTS
  Thirty-one percent of all patients had preoperative thickness <21 mm. Seven percent had <12 mm residual thickness after patellar cut, all were female. Twenty-three percent had ≥1 mm increase of thickness after surgery. Radiographs did not show any patellar fracture or implant loosening. However, preoperative patellar thickness <21 mm had poorer gain in range of motion at 1 year. Preoperative range of motion had greater influence on postoperative range of motion than preoperative patellar thickness. Residual thickness <12 mm had lower gain in WOMAC score at 1 year and an increase in thickness ≥1 mm postoperatively was associated with lower gain in WOMAC score at 6 months.
  
  
  CONCLUSIONS
  Early results of patellar resurfacing with preoperative thickness <21 mm or residual thickness <12 mm were found to be inferior even in the absence of patellar fracture or implant loosening. Conservative cutting resulting in 1 mm increase in thickness was also found to have inferior clinical results.
  
  
  METHODS
  II.
authors.affiliation: Joint Replacement Center, Yan Chai Hospital, Tsuen Wan, Hong Kong SAR, China, leejasper@gmail.com.
authors.forename: Qunn Jid
authors.initials: QJ
authors.lastname: Lee
authors.forename: Sze Tsun
authors.initials: ST
authors.lastname: Yeung
authors.forename: Yiu Chung
authors.initials: YC
authors.lastname: Wong
authors.forename: Yuk Leung
authors.initials: YL
authors.lastname: Wai
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D020370:Osteoarthritis, Knee / Q000473:pathology / Q000601:surgery*; D010329:Patella / Q000473:pathology* / Q000601:surgery*; D016059:Range of Motion, Articular; D020127:Recovery of Function