title: Intraoperative factors affecting conversion from cruciate retaining to cruciate substituting in total knee arthroplasty.
abstract: OBJECTIVE
  The purpose of this study was to analyse the factors affecting the conversion from posterior cruciate ligament (PCL)-retaining (CR) to PCL-substituting (PS) prostheses during total knee arthroplasty (TKA).
  
  
  METHODS
  A total of 920 TKAs, which had been preoperatively planned to undergo implantation of CR-type prostheses, were reviewed retrospectively. Of these, 83 knees (9.0 %) were converted intraoperatively to PS prostheses. The clinical and radiological factors of the non-converted (CR) and converted (PS) groups were compared. Clinically, age, gender, body mass index, angle of flexion contracture, size of the femoral component, and thickness of the polyethylene insert were compared between the CR and PS groups. Radiologically, the severity of the varus deformity and the posterior tibial slope angle (PSA) were compared between the CR and PS groups.
  
  
  RESULTS
  No significant differences in age, gender, body mass index, range of motion, thickness of the polyethylene insert, or severity of varus deformity were identified. The average preoperative angle of flexion contracture was 5.9° ± 7.4° in the CR group and 8.1° ± 9.1° in the PS group (p = 0.002). The average preoperative PSA was 9.6° ± 4.0° in the CR group and 11.0° ± 5.0° in the PS group (p = 0.018). The conversion rates to a PS-type femoral component of size C, D, and E were 13.1, 7.0, and 6.3 %, respectively (p = 0.004).
  
  
  CONCLUSIONS
  The conversion rate from CR- to PS-type prostheses was high in patients with severe flexion contracture, steep posterior slope, and a small femoral component size. These factors should be carefully considered for appropriate selection of prosthesis type.
  
  
  METHODS
  IV.
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University Seoul, 23 Kyunghee-daero, Dongdaemun-gu, Seoul, 024447, Korea.
authors.forename: Dae Kyung
authors.initials: DK
authors.lastname: Bae
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University Seoul, 23 Kyunghee-daero, Dongdaemun-gu, Seoul, 024447, Korea. songsjun@khmc.or.kr.
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Song
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University Seoul, 23 Kyunghee-daero, Dongdaemun-gu, Seoul, 024447, Korea.
authors.forename: Kang Il
authors.initials: KI
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University Seoul, 23 Kyunghee-daero, Dongdaemun-gu, Seoul, 024447, Korea.
authors.forename: Dong
authors.initials: D
authors.lastname: Hur
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University Seoul, 23 Kyunghee-daero, Dongdaemun-gu, Seoul, 024447, Korea.
authors.forename: Hyun Ho
authors.initials: HH
authors.lastname: Lee
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D000066491:Clinical Decision-Making; D003286:Contracture / Q000150:complications; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D007720:Knee Prosthesis; D008297:Male; D016119:Posterior Cruciate Ligament / Q000601:surgery*; D011474:Prosthesis Design; D017755:Prosthesis Fitting; D012189:Retrospective Studies
keywords: Conversion factor; Knee; PCL retaining; PCL substituting; TKA; TKR; Total knee arthroplasty; Total knee replacement