title: The influence of patellar resurfacing on patellar kinetics and retropatellar contact characteristics.
abstract: BACKGROUND
  Femoropatellar complications are one of the most common problems after total knee arthroplasty (TKA). However, the question of whether to resurface the patella remains controversial. Therefore, we evaluated the kinetics and the retropatellar contact characteristics of patella resurfacing with fixed and gliding surfaces.
  
  
  METHODS
  Eight Thiel-embalmed cadaver knees were tested--first intact, then after TKA without patellar resurfacing, and finally with additional patellar resurfacing--while flexing the knee from 0° to 100°. We tested a fixed as well as a gliding patella surface. During the examination, quadriceps and hamstring forces were applied. The retropatellar pressure was determined with a special patella sensor, and the patellar kinetics were measured using an optical three-dimensional motion analysis system.
  
  
  RESULTS
  Resurfacing the patella caused a significant increase in retropatellar pressure and a significant decrease in retropatellar contact area. Using a fixed patella, the retropatellar pressure nearly quadrupled in higher flexion compared to the native patella. Furthermore, the lateral movement of the patella increased after TKA, especially after additional patellar resurfacing.
  
  
  CONCLUSIONS
  Resurfacing the patella routinely is not advised. When osteoarthritis of the patella is found, the gliding patella should be preferred.
authors.affiliation: Institute of Biomechanics, Trauma Center Murnau, Prof.-Küntscher-Str. 8, 82418 Murnau, Germany. Simone.Wurm@bgu-murnau.de
authors.forename: Simone
authors.initials: S
authors.lastname: Wurm
authors.forename: Hans
authors.initials: H
authors.lastname: Kainz
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Reng
authors.forename: Peter
authors.initials: P
authors.lastname: Augat
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D006801:Humans; D007700:Kinetics; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis; D010329:Patella / Q000503:physiopathology / Q000601:surgery*; D011183:Postoperative Complications / Q000503:physiopathology / Q000601:surgery*; D016059:Range of Motion, Articular / Q000502:physiology*; D012086:Reoperation; D013499:Surface Properties