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Research: E. T. Davis, P. Gallie, K. Macgroarty, J. P. Waddell, and E. Schemitsch The accuracy of image-free computer navigation in the placement of the femoral component of the Birmingham Hip Resurfacing: A CADAVER STUDY J Bone Joint Surg Br 2007; 89-B: 557-560 [Abstract] [Full text] [PDF]

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Comparison of manual and image-less computer navigated jig in hip resurfacing arthroplasty

Rajeev Bansal, Hall Lane, Appley Bridge, Wigan, WN6 9EP   (3 August 2007)

Comparison of manual and image-less computer navigated jig in hip resurfacing arthroplasty 3 August 2007
Rajeev Bansal, Clinical Fellow Orthopaedics Wrightington Hospital,, Hall Lane, Appley Bridge, Wigan, WN6 9EP Send letter to journal: Re: Comparison of manual and image-less computer navigated jig in hip resurfacing arthroplasty smiraj{at}rediffmail.com Rajeev Bansal, et al.	Sir, I read this paper with great interest and I seek the authors' reply on a couple of observations on the methodology of the study. The authors state that "the use of image-free computer navigation can improve the accuracy of placement of the Birmingham Hip Resurfacing femoral component". The study compared the coronal plane angulation of the guide wire. However, for any pre-determined angle, it is equally important that the guide wire is centralised in the neck. A wire placed too inferiorly will notch the superior cortex of the femoral neck, whereas a wire placed too superiorly will leave the femoral component proud off the superior aspect of the head. This is a function of the resurfacing jig and a comparison should have been included in the assessment of the two instrumentations. The technical difficulty of placing a wire at an angle of 135°, without notching the femoral neck, will increase with increasing varus of the femoral neck. The study has used the contralateral femur as a control, however, it is not known if the neck-shaft angles were matched. It is known that the femoral neck-shaft angle can differ between the two sides even in normal individuals.1 R. Bansal, Clinical Fellow, Orthopaedics, Wrightington Hospital, Wigan, UK. 1. Reikeras O, Hoiseth A, Reigstad A, Fonstelien E. Femoral neck angles: a specimen study with special regard to bilateral differences. Acta Orthop Scand 1982;53:775-9.