Abstract
The femoral antero-posterior axis (AP or Whiteside’s Line) is one of the frequently used landmarks during total knee arthroplasty for determining rotation of the femoral component. Femoral morphology is assumed to be relatively constant and bone cuts made to prepare the distal femur are referenced from this landmark. Few studies have confirmed the consistency or reproducibility of this axis in normal femora even though the effect of malrotation on patella tracking and valgusvarus knee stability has been well documented.
Fifty normal (non-degenerate) cadaveric femora (27 right, 23 left) were studied. The AP axis was identified and marked on each. An end-on photograph was taken to give a two dimensional image. The transepicondylar axis (TEA) was then drawn on each image. The angle between these two axes was recorded.
Measurement of the TEA referenced from the AP axis gave a mean angle of 90.82 degrees (range 80–102; standard deviation=4.72).
This study shows that the femoral AP axis is a reasonable method of determining femoral component rotation during total knee arthroplasty. However the variance in the results would suggest that other landmarks should also be used as a means of cross-checking femoral component rotation.
The abstracts were prepared by Mr Roger Smith. Correspondence should be addressed to him at the British Association for Surgery of the Knee, c/o BOA, Royal College of Surgeons of England, 35–43 Lincoln’s Inn Fields, London WC2A 3PN.
