Imageless computer navigation without pre-operative templating may lead to malpreparation of the femoral head in hip resurfacing2009 M. 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
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.