Mechanical evaluation of proximal femoral reconstructions following 25%, 50% and 75% resection

The structural stiffnesses of a six proximal femoral reconstruction techniques were compared during ex vivo axial compression, mediolateral bending, and axial torsion in a canine model. Each femur was osteotomized at 25%, 50%, or 75% of its length and the proximal portion subsequently replaced using one of the six techniques thus creating an allograft/prosthesis composite (APC). These reconstruction techniques included various combinations of proximal and distal fixation methods (graft fixation/distal fixation): 1) Press-fit/Cement; 2) Cement/Cement; 3) Cement/Plates; 4) Cement/Screws; 5) Screws/Screws; 6) No Graft/Cement. Axial compression demonstrated a similar structural response when comparing all the reconstruction techniques overall and for each resection length. The mediolateral bending and axial torsion load applications did reveal a difference between techniques. The Cement/ Plates and No Graft/Cement constructs had significantly larger stiffnesses than the other four groups during mediolateral bending (p = 0.0001). During axial torsion, the Cement/Plates group was more stiff than the five other constructs (p = 0.0001) while the No Graft/Cement technique had a larger resistance to torsion than the remaining four constructs (p = 0.0001).