title: Patellar Cut and Composite Thickness: The Influence on Postoperative Motion and Complications in Total Knee Arthroplasty.
abstract: Little data exist on the influence of patellar thickness on postoperative motion or complications after total knee arthroplasty (TKA). This study addresses the following questions: Is postoperative motion influenced by change in composite patellar thickness? Is change in patellar thickness associated with more complications? And do more complications occur in the knees with a patellar bone remnant (<12 mm) and a native patellar thickness <18 mm?
  
  
  
  In total, 3655 TKAs were performed by 3 surgeons over a 28-year interval. All knees had caliper measurement of patellar thickness before the patellar cut, after implantation of the component and postoperative motion recorded in the database 1 or 2 years after TKA.
  
  
  
  Patellar composite thickness was the same (1034 knees), thicker (1617 knees), and thinner (1004 knees). A significant but weak relationship was identified between the change in patellar thickness and motion (P < .01, ρ = -0.046); an increase in "composite patellar thickness" of 10 mm would result in a 3° loss of knee motion. Significant differences were identified between change in thickness and manipulations (P < .05), ruptures (P = .01), and patellar clunk/crepitus (P < .01). Examining knees with bone remnant thicknesses (<12 mm/≥12 mm), there was no difference in fractures (P = .26). No extensor ruptures occurred in knees with remnant thickness <12 mm. Comparing knees with native bone thickness (≤18 mm/>18 mm), significant differences were found in fractures (P < .01) and patellar radiolucencies (P = .01).
  
  
  
  As this data does not demonstrate a strong tendency toward losing motion when the patellar thickness is increased, the authors recommend avoiding compromise of the patellar bone stock and tendon insertion. When native patellar bone is thin (<18 mm), we recommend maintaining 12 mm of patellar bone stock and accept the increase in composite thickness.
authors.affiliation: Anderson Orthopaedic Research Institute, Alexandria, Virginia.
authors.forename: William G
authors.initials: WG
authors.lastname: Hamilton
authors.affiliation: Anderson Orthopaedic Research Institute, Alexandria, Virginia.
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Ammeen
authors.affiliation: Anderson Orthopaedic Research Institute, Alexandria, Virginia.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Parks
authors.affiliation: Anderson Orthopaedic Research Institute, Alexandria, Virginia.
authors.forename: Nitin
authors.initials: N
authors.lastname: Goyal
authors.affiliation: Anderson Orthopaedic Research Institute, Alexandria, Virginia.
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Engh
authors.affiliation: Anderson Orthopaedic Research Institute, Alexandria, Virginia.
authors.forename: C Anderson
authors.initials: CA
authors.lastname: Engh
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000706:statistics & numerical data*; D005260:Female; D050723:Fractures, Bone / Q000209:etiology; D006801:Humans; D007717:Knee / Q000601:surgery; D007719:Knee Joint / Q000502:physiology* / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D009038:Motion; D010329:Patella / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology*; D011184:Postoperative Period; D016059:Range of Motion, Articular
keywords: complications; knee arthroplasty; motion; patellar composite thickness; patellar thickness