Quantification of holographic fringe data: comparison of intact and implanted femurs

The strains developed on the surface of a femur with and without an implanted femoral hip replacement were investigated using holographic interferometry (HI). Interferometric fringe data from the four aspects of the loaded femur were quantified and the resulting curvature calculated. Curvature was related to the strain along the long axis of the femur and the results for the intact and implanted femur compared. Changes were found in femoral strain patterns resulting from the implantation of both a cemented and an uncemented Norwich femoral component. All four aspects of the proximal 120 mm of the femur showed reduced strain as a result of prosthesis implantation irrespective of the method of prosthesis fixation. The distal half of the femur showed no such changes. No statistical difference was found between the loading patterns in the proximal femur of the uncemented and the cemented prosthesis.