title: Case-related factors affecting cutting errors of the proximal tibia in total knee arthroplasty assessed by computer navigation.
abstract: OBJECTIVE
  The aim of this study was to determine factors that contribute to bone cutting errors of conventional instrumentation for tibial resection in total knee arthroplasty (TKA) as assessed by an image-free navigation system. The hypothesis is that preoperative varus alignment is a significant contributory factor to tibial bone cutting errors.
  
  
  METHODS
  This was a prospective study of a consecutive series of 72 TKAs. The amount of the tibial first-cut errors with reference to the planned cutting plane in both coronal and sagittal planes was measured by an image-free computer navigation system. Multiple regression models were developed with the amount of tibial cutting error in the coronal and sagittal planes as dependent variables and sex, age, disease, height, body mass index, preoperative alignment, patellar height (Insall-Salvati ratio) and preoperative flexion angle as independent variables.
  
  
  RESULTS
  Multiple regression analysis showed that sex (male gender) (R = 0.25 p = 0.047) and preoperative varus alignment (R = 0.42, p = 0.001) were positively associated with varus tibial cutting errors in the coronal plane. In the sagittal plane, none of the independent variables was significant.
  
  
  CONCLUSIONS
  When performing TKA in varus deformity, careful confirmation of the bone cutting surface should be performed to avoid varus alignment. The results of this study suggest technical considerations that can help a surgeon achieve more accurate component placement.
  
  
  METHODS
  IV.
authors.affiliation: Department of Orthopaedic Surgery, Chiba Rehabilitation Center, 1-45-2 Hondacho, Midori-Ku, Chiba, Japan. mdddd940@ybb.ne.jp.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Tsukeoka
authors.affiliation: Department of Orthopaedic Surgery, Chiba Rehabilitation Center, 1-45-2 Hondacho, Midori-Ku, Chiba, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tsuneizumi
authors.affiliation: Department of Orthopaedic Surgery, Chiba Rehabilitation Center, 1-45-2 Hondacho, Midori-Ku, Chiba, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Yoshino
authors.affiliation: Research Center for Frontier Medical Engineering, Chiba University, Chiba, Japan.
authors.forename: Mashiko
authors.initials: M
authors.lastname: Suzuki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D019300:Medical Errors; D008875:Middle Aged; D010329:Patella / Q000601:surgery; D011446:Prospective Studies; D016059:Range of Motion, Articular; D025321:Surgery, Computer-Assisted; D013977:Tibia / Q000601:surgery*
keywords: Computer navigation; Cutting error; Proximal tibia; Total knee arthroplasty