Comparative outcomes of delta-on-delta and delta-on-highly cross-linked polyethylene bearings in total hip arthroplasty: a nationwide cohort study

INTRODUCTION: The purpose of this study was (1) to evaluate the national trends of Delta ceramic and highly crosslinked polyethylene (HXLPE) liner in total hip arthroplasty (THA), and (2) to compare survivorship of Delta ceramic versus HXLPE liner when used with a Delta ceramic head. MATERIALS AND METHODS: Using the K-NHIS database, we identified all patients who underwent primary THA using Delta ceramic head in South Korea between 2003 and 2013 (n = 16,250). Cumulative incidences of dislocation, periprosthetic joint infection (PJI), and periprosthetic fracture were evaluated according to bearing type: Delta-on-Delta ceramic (DoD) and Delta-on-HXLPE (DoHXLPE). Survivorship for revisions was calculated to determine differences. Multivariable Cox proportional hazard regression models were used for comparisons, and propensity score matching was additionally performed as a sensitivity analysis. RESULTS: A total of 15,299 patients underwent THA with Delta ceramic head between 2003 and 2013. Delta liner was used in 14,255 patients (93.2%) and HXLPE in 1,044 patients (6.8%). Utilization of Delta liner has noticeably increased since 2007. The DoHXLPE group had a higher risk of PJI (aHR = 2.10, 95% CI = 1.29-3.41) compared to the DoD group within 1 year. There were no significant differences in risk of dislocation (aHR = 1.41, 95% CI = 0.97-2.05) and periprosthetic fracture (aHR = 0.90; 95% CI = 0.39, 2.07) within 1 year. After 10 years, the DoHXLPE group had a higher risk of any revision (aHR = 1.32; 95% CI = 1.03, 1.38) compared to the DoD group, despite the similar risk of cup revision and stem revision. In the propensity score-matched cohort, the increased risk of PJI remained significant, whereas the point estimate for any revision remained higher in the DoHXLPE group but was no longer statistically significant. CONCLUSION: DoHXLPE bearings were associated with a higher risk of PJI than DoD bearings. However, the difference in the risk of any revision was not statistically significant in the propensity score-matched analysis.