Histological and biomechanical study of impacted cancellous allografts with cement in the femur: a canine model

Introduction  An experimental canine model was used for quantitative histological study using bone morphometry and biomechanical study on impacted cancellous allografting with cement in revision total hip arthroplasty. Materials and methods  The prosthesis had a collarless polished titanium alloy tapered stem with a head diameter of 15 mm. Twelve Beagle dogs were used. Cancellous bone grafts were obtained aseptically from the femoral condyles of other beagles. Histological examinations were performed up to 1 year after surgery. Biomechanical examinations were performed at 8 weeks after surgery. Results  The new bone formation proceeded from the proximal part to the distal site of the femur in the long axis as well as from the host cortical bone to the cement layer. Bone morphometry showed that the mineral apposition rate was higher in the proximal site of the femur than in the distal site at 8 weeks after surgery, but no significant differences were observed at other times. The bone formation rate was higher in the proximal site of the femur at 8 weeks after surgery, while it increased in the distal site at 16 weeks postoperatively but had decreased at 1 year after surgery significantly. The load test at 8 weeks after surgery showed that there was no significant difference at all sites attached strain gauge between impacted cancellous allograft group and control group. Conclusion  We concluded that biological replacement of the grafted bone by new bone settled at 1 year after surgery in this experimental model. However, the process was not completed.