title: Does computer-assisted surgery improve accuracy and decrease the learning curve in hip resurfacing? A radiographic analysis.
abstract: BACKGROUND
  Hip resurfacing is a technically demanding procedure in which accurate positioning of the femoral component is critical to the avoidance of early implant failures. The purpose of this study was to assess the accuracy of computer-assisted placement of the femoral component and to evaluate the impact of computer-assisted surgery on the learning curve associated with this procedure.
  
  
  METHODS
  The accuracy of positioning the femoral component was analyzed radiographically in hips undergoing resurfacing procedures performed by surgeons assigned to four different study groups: Group 1, in which the operations were performed with use of computer-assisted surgery by a fellowship-trained surgeon who was experienced in performing resurfacing arthroplasty (surgical experience, more than 250 hip resurfacings); Group 2, in which the operations were performed with use of computer-assisted surgery by senior residents who were inexperienced in performing resurfacing arthroplasty and who were closely supervised by faculty; Group 3, in which the operations were performed with use of conventional instruments by fellowship-trained faculty members; and Group 4, in which the operations were performed with use of computer-assisted surgery by a lesser experienced fellowship-trained faculty member (surgical experience, more than forty but less than seventy-five hip resurfacings) from Group 3.
  
  
  RESULTS
  The range of error in varus or valgus angulation that was observed for navigated procedures was 6 degrees in Group 1, 7 degrees in Group 2, and 5 degrees in Group 4. Compared with the preoperative neck-shaft angle value, the mean postoperative stem-shaft angle value increased by a mean of 4.7 degrees in Group 1, 7.2 degrees in Group 2, 6.5 degrees in Group 3, and 11.6 degrees in Group 4. When compared with the use of standard instrumentation, the use of computer-assisted surgery reduced the number of outliers and facilitated valgus insertion.
  
  
  CONCLUSIONS
  In the present study, computer-assisted surgery resulted in improved accuracy and precision in positioning the femoral component. In addition, computer-assisted surgery led to a reduction in the length of the learning curve for beginners in hip resurfacing and improved the surgeon's ability to perform this procedure safely.
authors.affiliation: Department of Orthopaedic Surgery, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1070, USA.
authors.forename: Thorsten M
authors.initials: TM
authors.lastname: Seyler
authors.forename: Lawrence P
authors.initials: LP
authors.lastname: Lai
authors.forename: Denise I
authors.initials: DI
authors.lastname: Sprinkle
authors.forename: William G
authors.initials: WG
authors.lastname: Ward
authors.forename: Riyaz H
authors.initials: RH
authors.lastname: Jinnah
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000193:education* / Q000379:methods; D002983:Clinical Competence; D005257:Fellowships and Scholarships; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D009985:Orthopedics / Q000193:education; D011474:Prosthesis Design; D011859:Radiography; D025321:Surgery, Computer-Assisted