Dual Mobility Hip — Principle, Indications, Advantages and Complications
DNB Orthopaedics • May 2024 • Paper IV • 10 Marks
Introduction
Dual mobility (DM) total hip arthroplasty is an acetabular bearing concept designed primarily to improve prosthetic hip stability and reduce the risk of dislocation.
It combines the concepts of a small femoral head articulation with a large effective head diameter. The system contains two articulations, hence the term dual mobility.
Core concept: Dual mobility increases jump distance and effective head size while retaining a low-friction inner articulation.
Historical Concept
The dual-mobility concept was developed in Europe to combine two desirable properties:
- Low-friction arthroplasty using a relatively small femoral head
- Improved stability using a large effective head diameter
Modern designs have improved polyethylene quality, cup fixation and neck geometry, reducing some of the complications seen with early generations.
Components of a Dual Mobility System
- Metal acetabular shell
- Large mobile polyethylene liner that articulates with the inner surface of the metal shell
- Small femoral head captured within the polyethylene liner
- Femoral neck/stem similar to conventional THA
DUAL MOBILITY CONSTRUCT
Metal acetabular shell
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Large mobile polyethylene liner
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Small femoral head
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Femoral neck
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Femoral stem