CORRInsights®: Exchangeable Femoral Neck (Dual-Modular) THA Prostheses Have Poorer Survivorship than Other Designs: A Nationwide Cohort of 324,108 Patients
As with most addictions, some negative consequences arose from our fascination with modularity. There was the recognition that even the time-tested modular head-neck junction was a source of clinically important metal corrosion debris, occasionally causing severe adverse local tissue reactions . Shortly thereafter, the modular junction between the neck and body of the femoral stem caused similar problems with specific stem designs [4, 7], albeit at a much earlier time point and at a much higher prevalence than that seen at the modular head-neck junction . These dual-modular designs were subject to other unique failure mechanisms such as implant fracture  and disassociation .
Owing to these case reports, case series, and recalls of specific implant designs, dual-modular stems have mostly fallen out of favor. However, many designs still remain on the market and are available for use today. Several studies have demonstrated high complication rates with specific dual modular stem designs [9, 11, 14], yet it remains unclear whether this high failure rate is isolated to a handful of specific designs, or if it extends to the entire class of dual-modular stems.
In the current study, Colas and colleagues report the survivorship results of dual modular stems compared to monolithic designs in a registry analysis of 324,108 patients who underwent THA in France between 2009 and 2012. They found that dual-modular THAs had lower survivorship than their monolithic counterparts. This should lead us to question the routine use of dual-modular stems.