Dual mobility: a review of the current state
Background: The dual mobility (DM) concept in total hip arthroplasty (THA), developed over 45 years ago, has evolved from a French innovation into a globally recognized solution for preventing prosthetic instability. A comprehensive understanding of its biomechanical principles, design variations, and the distinction between monobloc and modular systems is essential for optimal clinical application.
Objective of the Article: This article provides a detailed review of the dual mobility concept, tracing its historical development from the original Tripod cup to contemporary designs. It aims to elucidate the biomechanical principles underpinning its superior stability and range of motion, compare the performance of monobloc (DMC) versus modular (MDM) systems, and discuss the clinical relevance of different prosthetic designs.
Key Points / Core Message: The core principle of DM involves two articulations, providing an unmatched combination of increased range of motion and enhanced stability. This is characterized by a significantly greater "jump distance" compared to conventional implants, resulting in exceptionally low dislocation rates (0.4% at 10 years in a large series). The evolution to symmetrical, cylindro-spherical designs has further optimized intrinsic stability. The article highlights the biomechanical superiority of the original monobloc DMC concept over MDM systems, which are associated with reduced stability due to smaller liner diameters and risks of fretting corrosion and metal ion release at the modular junction.
Conclusion / Implications for Practice: The dual mobility concept is a proven and durable solution in THA that effectively addresses prosthetic dislocation, with excellent long-term survival. A critical takeaway for surgeons is the biomechanical advantage of monobloc, cylindro-spherical DMC designs over modular MDM systems, which carry inherent risks of instability and adverse local tissue reactions. DM stands as a benchmark in modern hip replacement surgery.
