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Journal of Bone and Joint Surgery - British Volume, Vol 91-B, Issue 10,
1281-1286.
doi: 10.1302/0301-620X.91B10.22020 Copyright © 2009 by British Editorial Society of Bone and Joint Surgery Imageless computer navigation without pre-operative templating may lead to malpreparation of the femoral head in hip resurfacingM. Olsen, BScE, PhD, Doctoral Researcher1; E. T. Davis, MSc, FRCSC(Trauma & Orth), Consultant Orthopaedic and Trauma Surgeon2; M. Chiu, MD, FRCSC, Orthopaedic Surgical Fellow1; P. Gamble, MD, FRCSC, Orthopaedic Surgical Felllow1; N. Tumia, MD, FRCSCEd(Trauma & Orth), Orthopaedic Surgical Fellow1; R. A. Boyle, MD, FRACS, Orthopaedic Surgical Fellow1; and E. H. Schemitsch, MD, FRCSC, Professor of Surgery1
1 Division of Orthopaedic Surgery St. Michaels Hospital, University of Toronto, 800-55 Queen Street East, Toronto, Ontario, Canada M5C 1R6. Correspondence should be sent to Dr M. Olsen; e-mail: olsenmi{at}smh.toronto.on.ca
The computed neck-shaft angle and the size of the femoral component were recorded in 100 consecutive hip resurfacings using imageless computer-navigation and compared with the angle measured before operation and with actual component implanted. The reliability of the registration was further analysed using ten cadaver femora. The mean absolute difference between the measured and navigated neck-shaft angle was 16.3° (0° to 52°). Navigation underestimated the measured neck-shaft angle in 38 patients and the correct implant size in 11. Registration of the cadaver femora tended to overestimate the correct implant size and provided a low level of repeatability in computing the neck-shaft angle. Prudent pre-operative planning is advisable for use in conjunction with imageless navigation since misleading information may be registered intraoperatively, which could lead to inappropriate sizing and positioning of the femoral component in hip resurfacing.
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