Total hip replacement page CORL website

Total Hip Replacement

The focus of our current effort is the skeletal response to long-term total hip replacement. we are most interested in identifying factors that may contribute to premature failure of the hip replacement. Some of these factors include the mechanical environment of the implant-bone junction and wear particles generated by the implants. All femurs are collected from an ongoing hip retrieval program. The implanted femurs are sectioned and histologically compared to the opposite non-implanted femurs (when only a unilateral hip replacement has been performed). This has provided important information regarding the long-term response of the bone to the presence of an implant.

Figure 1: this represents a contact radiograph of an implanted femur collected through our hip retrieval program and represents a case of instability. This implant had failed, but there were no discernible clinical signs of lameness at the time of the animal's death from unrelated causes. Note the black shadow around the implant; this represents a space between the implant and bone cement commonly seen in cases of implant loosening.

Figure 2: this represents two microscopic sections from different animals that had long-term hip replacement. The section on the left is bone from an animal that had a loose or unstable femoral implant; the section on the right is bone from an animal that had a stable implant. Note the size of the holes within the unstable bone compared to the stable bone. These holes represent resorption (removal) of bone. The removal of bone is much greater in unstable compared to stable hip replacement and may represent one of the factors that contributes to early failure of the hip replacement.