Abstract
Background:In recent decades, the popularity of modular necks in total hip arthroplasty (THA) has increased since modular necks offer the potential to restore the patient’s native anatomy, and thus improve stability. Unfortunately, modular necks are associated with higher complication rates, including implant fracture and modular junction corrosion with adverse local tissue reaction to metal debris.Objective:The objective of this study was to determine the impact of modular neck material on titanium (Ti), chrome (Cr), and cobalt (Co) metal ion levels in patients who underwent a THA with Ti femoral stem, Ti or CrCo modular neck, and ceramic-on-ceramic (CoC) bearing.Methods:Whole blood Ti, Cr, and Co levels were compared at a minimum 1-year follow-up in 36 patients who underwent unilateral, primary CoC large-diameter head THA with Profemur® Preserve modular femoral stems (MicroPort, Arlington, TX, USA).Results:Higher Co concentrations were observed in the CrCo modular neck group (0.46 versus 0.26 µg/l in the Ti neck group, P=0.004) and higher Ti concentrations were observed in the Ti modular neck group (1.98 vs 1.59 µg/l in the CrCo neck group, P=0.007). However, these differences were not clinically meaningful since the absolute values remained within what is considered the safe range of Ti, Cr, and Co ions in whole blood. No patients were re-operated or revised.Conclusion:Modular neck materials had an impact on whole blood metal ion levels but the concentrations measured remained within the safe range at 1-year follow-up. There were no indirect signs of modular junction corrosion with either CrCo or Ti femoral necks.
Highlights
Total hip arthroplasty (THA) is one of the most successful surgical procedures
No significant correlations were apparent between metal ion levels and follow-up time, body mass index (BMI), cup size, age, gender, and neck length
Modular necks may offer advantages, including reproducing the patient’s native anatomy during THA, some concerns remain about mechanically-assisted crevice corrosion and galvanic corrosion of the additional modular junction, and/or neck fracture
Summary
Total hip arthroplasty (THA) is one of the most successful surgical procedures. Over the last few decades, much research has been carried out with the goal of increasing implant durability, reducing complications, and improving the capacity of the implant to reproduce native hip anatomy and function. Some types of hip implants are associated with high complication rates, including modular junction corrosion, adverse local tissue reaction to metal debris (ARMD), and implant fracture [2 7]. On the other hand, is induced by highly-loaded metal surfaces that exist in a micromotion environment [8] This kind of corrosion leads to crevice formation, which, in turn, allows aqueous material to accumulate and become stagnant. The popularity of modular necks in total hip arthroplasty (THA) has increased since modular necks offer the potential to restore the patient’s native anatomy, and improve stability. Modular necks are associated with higher complication rates, including implant fracture and modular junction corrosion with adverse local tissue reaction to metal debris
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