title: Imageless computer navigation for placement of the femoral component in resurfacing arthroplasty of the hip.
abstract: We have investigated the accuracy of placement of the femoral component using imageless navigation in 100 consecutive Birmingham Hip Resurfacings. Pre-operative templating determined the native neck-shaft angle and planned stem-shaft angle of the implant. The latter were verified post-operatively using digital anteroposterior unilateral radiographs of the hip. The mean neck-shaft angle determined before operation was 132.7 degrees (118 degrees to 160 degrees ). The mean planned stem-shaft angle was a relative valgus alignment of 9.7 degrees (SD 2.6). The stem-shaft angle after operation differed from that planned by a mean of 2.8 degrees (SD 2.0) and in 86% of cases the final angle measured within +/- 5 degrees of that planned. We had no instances of notching of the neck or varus alignment of the implant in our series. A learning curve was observed in the time taken for navigation, but not for accurate placement of the implant. Navigation in hip resurfacing may afford the surgeon a reliable and accurate method of placement of the femoral component.
authors.affiliation: Division of Orthopaedic Surgery, Department of Surgery, St Michael's Hospital, University of Toronto, 30 Bond Street, Toronto, Ontario, Canada M5B 1W8.
authors.forename: M
authors.initials: M
authors.lastname: Olsen
authors.forename: E T
authors.initials: ET
authors.lastname: Davis
authors.forename: J P
authors.initials: JP
authors.lastname: Waddell
authors.forename: E H
authors.initials: EH
authors.lastname: Schemitsch
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery*; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D011859:Radiography; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome