Reduction of Micro‐Motion at the Tapered Connection of Hip Endoprostheses with an Adapted Deep Rolling Process of CoCrMo Inner Tapers

Abstract Modular hip joint replacements typically comprise a metal stem, a metal or ceramic ball, a polyethylene or ceramic acetabular cup inlay and a metal shell. Nevertheless, it is evident that this modularity represents a multitude of advantages and disadvantages. Implants retrieved from revision surgery showed evidence of abrasion and corrosion. Increased wear processes may occur. It is possible that these wear mechanisms could be reduced by functionalization of the surface. One potential method for inducing the transformation is through the utilization of a deep rolling process. As the metallic femoral heads are primarily composed of CoCrMo wrought alloy, this study employs a novel deep rolling tool to machine the inner conical bore (inner taper) of the femoral head. The resulting changes in mechanical and physical properties are investigated, as well as their influence on the clamping situation. A considerable enhancement is observed in the mechanical properties and a distinct reduction in surface irregularities, resulting in smoother morphologies after the deep rolling process. Along with the augmented mechanical properties, an improved clamping behavior is also achieved through the augmentation of torsional resistance, which subsequently reduces wear processes in the tapered connection and thus improves the implant.