Influence of Hip Prosthesis Size and Its Coating Area on Bone Remodeling

We developed a numerical model to describe the bone remodeling process in periprosthetic bone tissues and validated it by means of dual energy X-ray absorptiometry methods with different types of hip implants. In this paper, we applied the numerical model to investigate the influence of implant size and of the size of the porous coated area on bone remodeling in a periprosthetic human femur in an effort to define properties of implants, which would reduce bone remodeling after total hip arthroplasty. Two different sizes of a newly designed implant and three different coating area sizes were investigated in this paper. The results show that the smaller the implant, the less bone remodeling occurs. Reducing prosthesis size by 2mm from all sides has decreased bone remodeling by 14.4%. Extending the coating area on both, lateral and medial parts of the implant, has decreased bone remodeling in the lateral part of the femur and increased it in the medial part. In conclusion, depending on these results, the oversized hip replacement would cause more bone resorption in the femur. Concerning the coating area, the manufacturer must find a compromise between the small coating area with less bone remodeling in the medial part of the femur as well as less primary stability and the bigger coating area with less bone remodeling in the lateral part of the femur, but with higher bone remodeling in its medial part and more primary stability.