Are Metal Ion Levels Elevated After Dual Mobility Acetabular Systems: Minimum Five-Year Analyses.

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Toxicology

Background:

• Dual mobility systems in total hip replacement (THR) are associated with lower dislocation and revision rates.
• Concerns exist regarding elevated blood metal ion levels (cobalt, chromium) and potential adverse tissue reactions.
• Limited long-term (over five years) data exists on metal ion concentrations following dual mobility THR.

Purpose of the Study:

• To assess long-term (≥5 years) cobalt and chromium ion concentrations in blood and urine after dual mobility THR.
• To investigate variations in metal ion levels based on follow-up duration and specific implant characteristics.

Main Methods:

• A cohort of 57 patients who underwent THR with modular dual mobility systems was followed for an average of six years (range: 5-10 years).
• Serum, plasma, blood, and urine samples were analyzed for cobalt and chromium levels.
• Implant parameters including head composition/dimension, stem offset, cup dimension, and neck inclination were evaluated.

Main Results:

• Average cobalt concentrations in blood (0.8±0.6 mcg/L) and urine (1.2±1.0 mcg/L) were minimal and below standard limits.
• Average chromium concentrations in blood (0.9±0.2 mcg/L) and urine (1.3±0.5 mcg/L) were also minimal and below standard limits.
• No significant variations in metal ion concentrations were observed based on head material, follow-up duration, or implant metrics.

Conclusions:

• Dual mobility THR demonstrates clinically insignificant cobalt and chromium ion levels at a minimum of five years post-surgery.
• Metal ion concentrations remain within normal limits regardless of follow-up duration, head material, or implant specifications.
• These findings support the safety profile of dual mobility systems concerning metal ion release.