Risk factors for failure of the 36 mm metal-on-metal Pinnacle total hip arthroplasty system

Abstract

AimsTo determine ten-year failure rates following 36 mm metal-on-metal (MoM) Pinnacle total hip arthroplasty (THA), and identify predictors of failure.Patients and MethodsWe 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.ResultsFailure 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).ConclusionWe 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.

The risk of cardiac failure following metal-on-metal hip arthroplasty

“…[2][3][4] This has triggered regulatory alerts, device recalls and mandatory surveillance programs. The failure of these devices has led to many patients subsequently undergoing early revision.…”

Is the rate of revision of 36 mm metal-on-metal total hip arthroplasties with Pinnacle acetabular components related to the year of the initial operation?

“…3,[11][12][13] High revision rates have been reported for MoM THRs with Pinnacle cups (subsequently referred to as Pinnacles) in registries 3,11 and large single-centre studies. 12,[14][15][16][17] Two recent studies together involving over 1,000 primary 36 mm Pinnacles (8.4% of all such implants within the National Joint Registry (NJR)) both reported that hips implanted from 2006 onwards had a significantly increased risk of failure compared with those implanted before 2006. 12,17 Explant analysis also demonstrated that Pinnacles manufactured from 2006 onwards were increasingly likely to have lower clearance values than intended by the manufacturer.…”

“…12,[14][15][16][17] Two recent studies together involving over 1,000 primary 36 mm Pinnacles (8.4% of all such implants within the National Joint Registry (NJR)) both reported that hips implanted from 2006 onwards had a significantly increased risk of failure compared with those implanted before 2006. 12,17 Explant analysis also demonstrated that Pinnacles manufactured from 2006 onwards were increasingly likely to have lower clearance values than intended by the manufacturer. 12 It has been postulated that these previously unrecognised changes in the device manufacturing process may be responsible for the increased failure rates reported from 2006 onwards.…”

“…12 It has been postulated that these previously unrecognised changes in the device manufacturing process may be responsible for the increased failure rates reported from 2006 onwards. 12,17 These observations are concerning and, if specific to Pinnacle cups, may require important changes to surveillance for Pinnacle patients. [8][9][10] Assessment of the effect of year of Pinnacle implantation on revision rates in a large unselected population would therefore be advisable.…”

“…18 This study aimed to validate the findings from the two recent Pinnacle cohorts using the NJR dataset and novel statistical methodology. 12,17 We investigated whether five-year revision rates for 36 mm MoM THRs with Pinnacle cups, and for a control group of all other MoM THRs, were higher in primary hips implanted from 2007 onwards compared with those…”