The correlation between activity level, serum-ion concentrations and pseudotumours in patients with metal-on-metal hip articulations and metal-on-polyethylene total hip articulations.

PURPOSE

Young and physically active patients have mainly received metal-on-metal (MoM) total hip arthroplasty (THA) and resurfacing hip arthroplasty (RHA). However, the correlation between daily physical activity (PA) levels, serum-ion concentrations of chromium and cobalt and pseudotumours formation of patients who underwent MoM THA/RHA is insufficiently explored.

METHODS

Ninety-nine patients with 134 hip articulations, 71 MoM THA/RHA and 63 MoP THA participated in a cross-sectional study at XXX University Hospital, Denmark, at mean 7.3 (range: 0.4-21.7) years after surgery. Patients' daily PA was monitored during a two-week period using a triaxial accelerometer. Metal artefact reduction sequence magnetic resonance imaging scans, estimation of serum-ion concentrations of chromium and cobalt and the Copenhagen Hip and Groin Outcome Score (HAGOS) questionnaire were completed on Day 14.

RESULTS

Patients with a pseudotumour who underwent MoM THA/RHA had a higher average cadence of median 101.4 [interquartile range (IQR: 95.5-105)] steps/min than patients without a pseudotumor, median 96.7 (IQR: 92.2-103) steps/min (p = 0.02). Serum-ion concentrations of chromium and cobalt were higher in patients with a pseudotumour who underwent MoM THA/RHA, median 2.57 (IQR: 1.4-3.4) μg/L and 1.80 (IQR: 1.2-2.6) μg/L, respectively, than in patients without a pseudotumour, median 1.85 (IQR: 1.1-3.2) μg/L and 1.34 (IQR: 0.9-2.2) μg/L in MoM THA/RHA (p = 0.04 and p = 0.03). There was no statistical difference in these parameters between patients with and without a pseudotumour who underwent MoP THA. Daily PA levels of patients who underwent MoM THA/RHA were significantly correlated with serum-ion concentrations of chromium (p = 0.0002, r = 0.44) and cobalt (p = 0.005, r = 0.34), whereas no correlations were seen among patients who underwent MoP THA (p > 0.12).

CONCLUSION

The daily PA level of patients who underwent MoM THA/RHA influences the serum-ion concentrations of chromium and cobalt and the risk of pseudotumour formation.

TRANSLATIONAL POTENTIAL OF THIS ARTICLE

Results of this article add important knowledge on potential recommendations of prosthesis selection for patients with a high level of physical activity.