This study utilized data from the NJR dataset on all Corail/Pinnacle total hip replacements (THR) to determine (a) the level of unit variation of the Corail/Pinnacle 36mm Metal On Metal THR within England and Wales; (b) patient, implant and surgeon factors that may be associated with higher revision rates; (c) Account for the influence of the MHRA announcement in 2010. The national Revision Rate (RR) for the Corail / Pinnacle MOM THR was 10.77% (OR:1.46; CI:1.17–1.81). This was significantly greater than other articulation combinations (MOP 1.72%, COP 1.36%, COC 2.19%). The 2010 MHRA announcement did not increase rate of revision (X2=1649.63, df=13, p<.001). Patient factors associated with significantly increased revision rates included, female gender (OR 1.38 (CI 1.17–1.63, p<.001) and younger age OR 0.99 (CI 0.98–0.99), p<.001). Implant factor analysis demonstrated an inverse relationship between cup size and revision. As head length increased RR increased – highest risk of revision +12.5 (OR 1.69 (CI 1.12–2.55), p=0.13). Coxa vara, high offset stems had a higher risk of revision compared to standard offset stems (OR:1.41 (CI 1.15–1.74; p<.001). As stem size increased risk of revision decreased (OR 0.89 (CI 0.85–0.93); p<.001). Surgeon grade did not influence RR. There was significant variation in RR between hospitals with 7 units (7/61 excluding low volume centres, <50 implants) identified as having significant higher rates of revision. However, for each of these units there was a greater proportion of higher risk patients (female, cup size 50–54, stem type). This study has provided insight into unit variation, risk factors and the long term outcome of the Corail/Pinnacle 36mm MOMTHR. Future aims are to use these results to develop a risk stratified algorithm for the long term follow of these patients to minimize patient inconvenience and excess use of limited NHS resources.
The National Joint Registry (NJR) for England, Wales and Northern Ireland contributes important information on the performance of implants and surgeons. However, the quality of this data is not known. This study aimed to perform an independent validation of primary metal-on-metal hip procedures recorded on the NJR through linkage to the London Implant Retrieval Centre (LIRC). Primary, metal-on-metal hip arthroplasties performed between 1st April 2003 and 5th November 2013 were recruited from the NJR (n=67045). Retrieved, metal-on-metal components were recruited from the LIRC (n=782). Data linkage and validation checks were performed.Introduction
Patients/Materials & Methods
Arthroplasty registries are important for the
surveillance of joint replacements and the evaluation of outcome. Independent
validation of registry data ensures high quality. The ability for
orthopaedic implant retrieval centres to validate registry data
is not known. We analysed data from the National Joint Registry
for England, Wales and Northern Ireland (NJR) for primary metal-on-metal
hip arthroplasties performed between 2003 and 2013. Records were
linked to the London Implant Retrieval Centre (RC) for validation.
A total of 67 045 procedures on the NJR and 782 revised pairs of
components from the RC were included. We were able to link 476 procedures
(60.9%) recorded with the RC to the NJR successfully. However, 306
procedures (39.1%) could not be linked. The outcome recorded by the
NJR (as either revised, unrevised or death) for a primary procedure
was incorrect in 79 linked cases (16.6%). The rate of registry-retrieval
linkage and correct assignment of outcome code improved over time.
The rates of error for component reference numbers on the NJR were
as follows: femoral head category number 14/229 (5.0%); femoral head
batch number 13/232 (5.3%); acetabular component category number
2/293 (0.7%) and acetabular component batch number 24/347 (6.5%). Registry-retrieval linkage provided a novel means for the validation
of data, particularly for component fields. This study suggests
that NJR reports may underestimate rates of revision for many types
of metal-on-metal hip replacement. This is topical given the increasing
scope for NJR data. We recommend a system for continuous independent
evaluation of the quality and validity of NJR data. Cite this article: