In primary metal-on-metal total hip arthroplasties undertaken from 2007 onward, investigators found a significant increase in 5-year revision rates compared with those undertaken prior to 2007.
“The increased number of metal-on-metal hip implant patients undergoing further surgery in recent years is likely explained by changes made in how this group of patients are managed,” Gulraj S. Matharu, BSc (Hons), MBChB, MRCS, said in a press release from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR). “Our study findings are most likely attributable to the increase in regular patient follow-up combined with many surgeons now acting earlier to perform revision surgery.”
Gulraj S. Matharu
Matharu and colleagues used data from the NJR for 10,776 primary 36-mm metal-on-metal (MoM) THAs performed with Pinnacle acetabular components (De Puy Synthes) done between 2003 and 2012 and a control group of 13,817 other MoM THAs. Cox regression and interrupted time-series analysis were used to assess the impact of the year of the primary surgery on all-cause rates of revision.
Results showed higher revision rates in MoM THAs with Pinnacle components undertaken between 2007 and 2012 vs. those undertaken between 2004 and 2006. Investigators noted the number of revisions per 1,000 implant-years at risk increased significantly by 5.2 for THAs undertaken during and after 2004 vs. those undertaken prior to that period.
According to researchers, THAs in the control group that were undertaken between 2007 and 2012 had higher rates of revision. There was a 6.13 increase in revisions per 1,000 implant-years for THAs undertaken during and after 2007.
“Contrary to recent reports, this finding was not specific to those involving Pinnacle acetabular components and may be explained by increased surveillance and recent lowering of the threshold for revision,” the researchers wrote.
Matharu GS, et al. Bone Joint J. 2018;doi:10.1302/0301-620X.100B1.BJJ-2017-0625.R2.
Disclosure: Matharu reports that he receives financial or material support from Arthritis Research UK Clinical Research Fellowship, The Orthopaedics Trust, The Royal College of Surgeons of England, The Arthritis Research Trust and The Royal Orthopaedic Hospital Hip Research and Education Charitable Fund.