Comparing 1-year and 10-year whole blood metal ion results following Birmingham hip resurfacing for osteoarthritis.

BACKGROUND: Patients with metal-on-metal hip arthroplasty may develop adverse reactions to metal debris that can lead to clinically concerning symptoms, often needing revision surgery. As such, many regulatory authorities advocate for routine blood metal ion measurement. This study compares whole blood metal ion levels obtained 1 year following Birmingham Hip Resurfacing (BHR) to levels obtained at a minimum 10-year follow-up. METHODS: A retrospective chart review was conducted to identify all patients who underwent a BHR for osteoarthritis with a minimum 10-year follow-up. Whole blood metal ion levels were obtained at final follow-up in June 2019. These results were compared with patients' metal ion levels at 1 year. RESULTS: Of the 211 patients who received a BHR, 71 patients (54 males and 17 females) had long-term metal ion levels assessed (mean follow-up 12.7 ± 1.4 yr). The mean cobalt and chromium levels for patients with unilateral BHRs (43 males and 13 females) were 3.12 ± 6.31 µg/L and 2.62 ± 2.69 µg/L, respectively; for patients with bilateral BHRs (11 males and 4 females) cobalt and chromium levels were 2.78 ± 1.02 µg/L and 1.83 ± 0.65 µg/L, respectively. Thirty-five patients (27 male and 8 female) had metal ion levels tested at 1 year postoperatively. The mean changes in cobalt and chromium levels were 2.29 µg/L (p = 0.0919) and 0.57 µg/L (p = 0.1612), respectively. CONCLUSION: Our results suggest that regular metal ion testing as per current regulatory agency guidelines may be impractical for asymptomatic patients. Metal ion levels may in fact have little utility in determining the risk of failure and should be paired with radiographic and clinical findings to determine the need for revision.

Birmingham Hip Resurfacing for osteoarthritis - a Canadian retrospective cohort study with a minimum 10-year follow-up.

BACKGROUND: Young men with osteoarthritis of the hip are a growing segment of the population requiring arthroplasty, and there is compelling evidence that the Birmingham Hip Resurfacing (BHR) system provides good functional outcomes and durability in young, active men. We reviewed the survivorship and clinical outcomes of patients who underwent BHR with a minimum follow-up of 10 years. METHODS: We analyzed survivorship using the Kaplan-Meier method. Functional scoring was performed using the Harris Hip Score (HHS), the University of California, Los Angeles (UCLA) Activity Score, and a visual analogue scale (VAS). RESULTS: In total, 211 patients (243 hips) were included in the study. Of these, 107 patients (127 hips) were available for long-term clinical follow-up, with a mean duration of 12.4 ± 1.4 years. The proportion of male participants with BHRs surviving past 13 years was 93.8% (95% confidence interval [CI] 87.9%-100%) compared with 87% (95% CI 77.8%-97.3%) of female patients. Eleven patients (11 hips) underwent BHR revision. Upon final follow-up, the median HHS was 93.9 in males and 93.6 in females (p = 0.27); median UCLA Activity Score was 8.2 in males and 7.2 in females (p < 0.001), and the median VAS score was 81.9 in males and 81.3 in females (p = 0.35). The median acetabular component inclination was 45.5° ± 6.0° (range 34.6°-57.2°) in males and 44.6° ± 5.9° (range 29°-58.9°) in females. The most common femoral head size was 50 mm with a 56 mm or 58 mm cup (36.3%). CONCLUSION: This study confirms that BHR provides good to excellent functional outcomes, lasting functional improvements, and acceptable durability beyond 10 years in men. Survivorship following BHR is inferior in women; however, HHS and VAS scores were similar in women and men.