title: Cruciate-retaining TKA is an option in patients with prior patellectomy.
abstract: BACKGROUND
  The recommendation for using posterior-stabilized (PS) implants in patellectomy patients undergoing total knee arthroplasty (TKA) is based on older case series with heterogeneous patient populations. The use of cruciate-retaining implants in these patients has not been evaluated with more contemporary implant designs.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the survivorship and functional outcomes (Knee Society score, presence of an extensor lag, and range of motion) of cruciate-retaining (CR) TKA in patients with prior patellectomy.
  
  
  METHODS
  Between 1986 and 2012, we performed 27 CR TKAs in 25 patients after patellectomy. Of those, 23 CR TKAs in 21 patients were available for followup at a minimum of 2 years (mean, 11.2 years; range, 2.3-25.1 years). In this retrospective study, we queried a prospectively maintained database to assess functional outcomes and survivorship.
  
  
  RESULTS
  Aseptic loosening-free survival was 100% at 5 and 10 years, and survival with revision for any reason as the outcome was 96% at 5 years (95% confidence interval [CI], 87.7%-100%) and 84% at 10 years (95% CI, 69.5%-100%). One patient was revised for aseptic loosening at 10.2 years postoperatively. Mean Knee Society scores improved from 36±13 preoperatively to 92±9.6 at followup. Extensor lag was present in seven patients preoperatively and only three at followup. Average knee flexion at followup was 112°±12.5°.
  
  
  CONCLUSIONS
  In this study we found good long-term survivorship and functional outcomes with a CR implant design in patients following patellectomy. Earlier studies have favored PS over CR implants for patients with patellectomies. We believe this series suggests that CR TKA is indeed an option in patients with patellectomy.
  
  
  METHODS
  Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, North Shore LIJ Orthopaedic Institute at Southside Hospital, 301 East Main Street, Bayshore, NY, 11706, USA, krr9009@gmail.com.
authors.forename: Keith R
authors.initials: KR
authors.lastname: Reinhardt
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Huffaker
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Thornhill
authors.forename: Richard D
authors.initials: RD
authors.lastname: Scott
mesh_terms: D000368:Aged; D016118:Anterior Cruciate Ligament / Q000503:physiopathology / Q000601:surgery*; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods*; D001696:Biomechanical Phenomena; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D010027:Osteotomy; D010329:Patella / Q000601:surgery*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012086:Reoperation; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome