Aims. To determine ten-year failure rates following 36 mm metal-on-metal
(MoM) Pinnacle total hip arthroplasty (THA), and identify predictors
of failure. Patients and Methods. We retrospectively assessed a single-centre cohort of 569 primary
36 mm MoM Pinnacle THAs (all Corail stems) followed up since 2012
according to Medicines and Healthcare Products Regulation Agency
recommendations. All-cause failure rates (all-cause revision, and
non-revised cross-sectional imaging failures) were calculated, with predictors
for failure identified using multivariable Cox regression. Results. Failure occurred in 97 hips (17.0%). The ten-year cumulative
failure rate was 27.1% (95% confidence interval (CI) 21.6 to 33.7).
Primary implantation from 2006 onwards (hazard ratio (HR) 4.30;
95% CI 1.82 to 10.1; p = 0.001) and bilateral MoM hip arthroplasty
(HR 1.59; 95% CI 1.03 to 2.46; p = 0.037) predicted failure. The
effect of implantation year on failure varied over time. From four
years onwards following surgery, hips implanted since 2006 had significantly higher
failure rates (eight years 28.3%; 95% CI 23.1 to 34.5) compared
with hips implanted before 2006 (eight years 6.3%; 95% CI 2.4 to
15.8) (HR 15.2; 95% CI 2.11 to 110.4; p = 0.007). Conclusion. We observed that 36 mm MoM Pinnacle THAs have an unacceptably
high ten-year failure rate, especially if implanted from 2006 onwards
or in bilateral MoM hip patients. Our findings regarding implantation
year and failure support recent concerns about the device manufacturing
process. We recommend all patients undergoing implantation since
2006 and those with bilateral MoM hips undergo regular investigation,
regardless of symptoms. Cite this article: Bone Joint J 2017;99-B:592–600