A novel constrained acetabular liner design with increased range of motion.

One treatment strategy for recurrent dislocation after total hip arthroplasty is the use of a constrained acetabular component. A major drawback of currently available constrained components is the limited range of motion (ROM). We present a novel constrained component that employs a monopolar, highly cross-linked polyethylene liner with cutouts oriented to allow increased ROM, while maintaining constraint against dislocation. ROM and lever-out tests comparing this novel design with a conventional constrained component showed that the cutaway monopolar component allowed ROM substantially greater than a currently available design. The lever-out torque for the cutaway monopolar constrained component was 243% higher than the conventional constrained component. This novel constrained acetabular component offers promise for providing excellent constraint against dislocation, while maintaining a wide ROM.