Total hip arthroplasty with dual-mobility components is associated with excellent clinical outcomes and low metal ion blood levels at 2 years.

BACKGROUND: Dual-mobility (DM) prostheses have been developed to reduce dislocation risk of total hip arthroplasty (THA), but concerns exist regarding potential local and systemic metal ion release. The study aimed to assess the 2-year clinical outcomes, and whole blood metal ions levels following THA with the Trinity DM system.

METHODS: Eligible patients (n = 104) underwent consecutive primary THA with a Trinity DM prosthesis. Patient-reported outcome measures (PROMs) were completed by 101 (99%) at baseline and 2 years. Whole blood cobalt (Co), chromium (Cr) and titanium (Ti) levels were measured at baseline in 19 and 2 years in 53. PROMs included Oxford Hip Score (OHS), HOOS-JR, and satisfaction.

RESULTS: At 2 years, 96% were satisfied or very satisfied. PASS thresholds were achieved by 85% for HOOS-JR and 87% for OHS. Mean blood levels increased from baseline to 2 years for Co 6 to 8 nmol/L (p = 0.348), Cr 10 to 11 nmol/L (p = 0.824) and Ti 44 to 86 nmol/L (p = 0.001). Elevated levels (>1.0 µg/L) were observed for Co 7.5%, Cr 1.8%; and Ti >5 µg/L in 9 (17%), but were well below thresholds associated with significant prosthetic wear.

CONCLUSIONS: The Trinity modular DM system demonstrated excellent 2-year clinical outcomes and acceptable low blood metal ion levels. Baseline and periodic 5-year metal ion surveillance is recommended after modular DM THA.ANZCTR Clinical Trial No:ACTRN12622000003774.