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NJR Developments

Benefit articles

In this NJR 20th anniversary year our patient representatives, the clinical leadership and NJR management team, together with the Lot 1 and Lot 2 contractors, have been reflecting on the value that the NJR dataset has brought to joint replacement healthcare, both in the UK and beyond.

We have summarised these benefits in a series of articles being published in the Journal of Trauma and Orthopaedics (JTO) over the anniversary year (with the first of these having been published in June 2023). These articles cover the benefits the NJR provides for our stakeholder groups: patients, hospitals, surgeons, industry, service commissioners, regulators, policy-makers, and broader society, and are also addressed and summarised on the NJR website.

Component classification database

In 2018, the NJR started working in collaboration with the German Arthroplasty Registry (known as EPRD) to develop a common classification system for defining the attributes of hip and knee joint replacement components. This classification has now been adopted by both registries with each managing their own local databases, which are currently being populated by all of our international and domestic industry implant suppliers.

Our own component database is now fully implemented across NJR Supplier Feedback services and the populating of attributes is in progress by industry. Use of this classification data for NJR reporting has commenced in some areas and will be further rolled out once classification data from industry is sufficiently complete.

Both the NJR and EPRD have now agreed to license the component classification system to the International Society of Arthroplasty Registers (ISAR) for their International Prosthesis Library (IPL) platform, meaning the hip and knee components can be classified in the same way in registries across much of the world. This work will provide numerous valuable benefits: improving the comparability of data, increasing the opportunity to pool results for identifying poor performance outcomes and decreasing the burden on industry colleagues in data upload across multiple systems.

During FY2022/23, we also began working closely with our international colleagues to start developing a common classification system for shoulder replacement surgery, which will feed into our development of a shoulder component database.

Patient Reported Outcome Measures (PROMs)

The NJR PROMs working group, which is led by Professor Mark Wilkinson, the Chair of the NJR’s Research Committee, oversees the NJR workstreams that involve the collection, analysis and reporting of patient reported outcome metrics.

Assessment of PROMs data quality: 

PROMs data for hip and knee replacement surgery is not routinely collected by the NJR, but is a separate programme managed by NHS Digital (now part of NHS England). The NJR has accessed national PROMs data annually through an application to NHS Digital’s Data Access Request Service.

As the NJR increasingly used metrics from the national PROMs programme (undertaken by NHS England), alongside revision and mortality endpoints, an examination of the quality and representativeness of national PROMs for the population of patients in England who have hip and knee replacement surgery was undertaken last year. This important work, carried out by the University of Bristol and University of Oxford on behalf of the NJR, recommended the reporting of PROMs using tables. (Please see last year’s annual report for our full analysis (

Unfortunately, due to circumstances beyond our control, we have not been able to secure access to these datasets this year. NHS England report that, “In 2021 significant changes were made to the processing of Hospital Episode Statistics (HES) data and its associated data fields which are used to link the PROMs-HES data. Redevelopment of an updated linkage process between these data are still outstanding with no definitive date for completion at this present time. This has unfortunately resulted in a pause in the current publication reporting series for PROMs at this time.”

NHS England is currently working to identify solutions and once this is resolved we hope to be able to readdress the reporting of PROMs in the next NJR Annual Report. We are disappointed that we are unable to proceed with this important work to consider these outcomes in respect of implant performance.

Shoulder PROMs collection is overseen directly by the NJR within our geographical areas of operation and so is unaffected by these issues. Please see the shoulder section of the PDF version of the NJR Annual Report for more information about shoulder PROMs.

Use of PROMs in implant reports: The NJR has routinely included reporting of PROMs metrics in implant reports that are made available to manufacturers via the ‘NJR Supplier Feedback’ reporting service. This has meant that patient reported metrics could be considered alongside revision rates when examining the performance of an implant or construct. Increasingly, regulatory bodies internationally are requiring PROMs to be included as part of industry submissions to support device assurance, however, this is also affected by the above-mentioned pause in the availability of PROMs data within NHS England.

Shoulder PROMs: For shoulder replacement joint surgery, we commenced six-month follow-up questionnaires in April 2017 for patients who had undergone surgery after 1 October 2016. We continue to find outcome comparison of before and after surgery challenging to understand, due to a disappointingly low rate (<25%) of pre-operative PROMs submissions and we encourage units to capture this important data from all of their patients. Response rates to questionnaires sent directly to patients at their home addresses post-surgery averages at just over 80%.

Research Programme

With such a rich data pool of now around 3.7 million records, the NJR’s research activity has been continually developing over a long period of time and has led to a great number of important and impactful publications, all delivering valuable evidence about how effectively joint replacement surgery works, with the key aim of this research knowledge being used to ensure patient safety and support the improvement of surgery outcomes.

The NJR commissions an ongoing programme of research with the University of Bristol and University of Oxford and this focuses on four specific research topics for a detailed examination. These projects are jointly led by a clinician from the NJR team and a clinical academic from the University of Bristol, providing ongoing guidance for expert statisticians in the work, to ensure that the analysis is of the highest possible quality.

The current NJR research programme consists of these four topics:

  • Inequalities in provision and outcomes of joint replacement performed in England
  • Factors associated with revision and its outcomes
  • Examination of data quality in the national PROMs programme
  • Outcomes associated with operation-type in shoulder surgery

We also support external researchers to access and use NJR data for research, shared under strict data control measures. The NJR Research Committee reviews submissions from researchers across the country and advises and supports in ensuring that NJR data can be best used to inform and improve practice. A full portfolio of external research applications can be found here. Over 70% of all research projects are now led by groups external to the NJR and we continue to work closely with external researchers to improve accessibility further.

Last year we held our first ‘NJR Research Webinar’ focusing on our approach to supporting researchers in accessing NJR data for their studies. We were delighted to welcome prospective research applicants from across the UK to hear presentations on data access and analysis from our expert team. The presentations have been compiled into a video of the event and is freely available to all on our Youtube channel.

The NJR Data Access Portal (DAP) has been developed to streamline research applications by providing a secure working environment, including analysis tools, for researchers and other users of NJR data, whilst enabling the NJR to stringently manage and control access to our data more effectively. By providing access to the data without the need for datasets to be sent to third-parties, it is anticipated that the governance burden that research teams have previously faced will be significantly reduced. 

Implant scanning / never events

In 2018, the NHS Healthcare Safety Investigation Branch identified a requirement to reduce the number of ‘Never Events’ associated with joint replacement surgery. The NJR was identified as a means by which this could be achieved. 

For hip surgery, a Never Event is where there is a mismatch in size between the acetabular cup/liner and the head, or where different brands of head and stem are used in modular components. For a knee procedure, a Never Event relates to side, e.g. a left-sided component being put into a right knee. 

To address this potential problem, the NJR’s data entry system was updated to enable it to detect potential Never Events and to warn the data entry user. At the same time as warning the user, the system generates an email to NJR staff so that this alert can be investigated. If an alert is confirmed as a genuine Never Event, the Consultant in Charge of the patient is then contacted by a surgeon member of the NJR clinical team to confirm what action will need to be taken. 

A very small number of actual Never Events are identified in this way each year but the number of ‘false alarms’ is considerably higher. These alarms are most often likely to be due to mistakes in the data entry process, such as having selected the wrong side for the operation or having input the wrong label details when recording the implants.

As part of this focus on Never Events, we have worked to deliver the validation rules that are applied in data entry to an external environment, so that it can be used in support of intra-operative checks. We have developed an Application Programming Interface (API) so that hospital theatre systems can interface with NJR’s checking rules. We have also developed an application that can be used on desktop or mobile devices so that clinical teams can carry out validation checks even if their hospital does not have a compatible front-end system. To date over 19,000 checks carried out using the implant scanning tools.

For more information about how to access the NJR’s implant scanning tools, please visit our website.

Minimum Data Set (MDS) development

Since the National Joint Registry (NJR) was launched in 2003, we have periodically reviewed and updated the procedure data that we collect for each joint, to ensure that we are capturing data relevant to contemporary joint replacement practice and can achieve our objectives to monitor the quality and safety of orthopaedic services.

We call this data collection our ‘Minimum Data Set’ (MDS) and there have been many progressive advancements in surgical procedures since the last review for MDSv7. This year therefore, we have been through an exercise to review the developments we need to implement to enable us to update the MDS and we have consulted with relevant orthopaedic specialist societies on these changes and feel that these represent a major step forward in enabling the NJR to fully monitor the outcomes of all current joint replacement procedures.

We have also reviewed, mapped out changes needed, and fully updated the software for our hospital data entry system to enable input of the new procedures contained in the new MDSv8 forms that were circulated for use for data entry from June 2023. These changes are in line with the increased vigilance of implanted devices engendered by the Cumberlege report and the newly developed Medical Device Registries and Outcomes Programme.

The key changes to the dataset to be collected are:

  • Primary hip hemiarthroplasty is now collected as part of the MDSv8. Conversions to a total hip replacement (THR) from a hemiarthroplasty are now recorded on a H2 revision form
  • A new form (RO) to capture ‘Reoperations other than revision’ has been introduced for non-revision operations involving joint replacements. These include fixation of periprosthetic fracture, manipulation under anaesthesia, soft tissue repairs and DAIR without modular exchange. Procedures where one or more components are added to, removed from or modified in a joint replacement will continue to be recorded on the relevant revision forms
  • Dual consultant operating is now able to be recorded on all forms in cases where two consultants are operating together (as opposed to one assisting the other)
  • Focal knee replacements are now recorded on knee primary (K1) forms and conversion from focal replacements to unicompartmental or total knee replacements are recorded on knee revision (K2) forms
  • The complexity of hip and knee revision surgery are captured on revision (H2 and K2 forms)
  • Glenoid morphology is collected as part of shoulder primary (S1) forms
  • A new field has been added to all primary forms to indicate that a procedure has been performed in the context of a clinical trial

A further data set release is planned for April 2024 to introduce a new form for megaprothesis, to be used in cancer-related or complex trauma surgery.

For more information about MDSv8, please see our website here.

NJR Connect – Data Services

In 2019, we commissioned the development of a cloud-ready, platform-based application framework for provision of future NJR services. The rationale for the implementation of the new NJR IT platform includes a focus on the need to develop a modern, unified environment with the ability to move to a cloud-based infrastructure. The platform development will include enabling new services that will transfer across stakeholder user groups, so that functionality and developments can be replicated across all systems on the portal. Optimisation of modules for access on mobile devices will also be included.

The first phase of development (iteration 1) transferred clinician feedback services into the new environment along with a more interactive reporting service. This was launched in March 2021 and included the following modules:

  • Interactive outcomes and clinical practice reports
  • Consultant and Surgeon Level Report (CLR & SLR)
  • Annual Clinical Report (ACR)
  • Clinical Outcomes Publication Preview (COP)
  • Clinician Profile Edit
  • User Contact Database

Iterations 2 and 3 followed during FY2021/22 and included development of other NJR services:

  • Component Database
  • Supplier Feedback, including interactive reporting services (SF)
  • Interactive Management Feedback Service (MF)
  • New availability of Implant Data Library

NJR data entry was moved onto NJR Connect in time to enable MDSv8 to be integrated into the data collection system for its launch in June 2023.

We are continuing to look at further opportunities to enhance the capability of NJR Connect to provide reporting services to all our stakeholder user groups and expect to implement a continuous programme of enhancements over the coming years.

NJR Data Quality Audit

Our Data Quality Audit has been devised to assess the completeness and quality of the data submitted to the registry. This enables us to compare patient records for procedures recorded in local hospitals’ databases (e.g. Patient Administration Systems (PAS) to that in the registry, with the aim of investigating the accuracy of the number of joint replacement procedures submitted to the registry, compared to the number carried out.

The importance of the NJR Data Quality Audit is clear when considered in the context of our primary aims. To achieve those aims, there are two principal outcomes of interest to the NJR: revision surgery and mortality volumes.

The occurrence of revision surgery is often an indicator of either implant failure or poor surgical performance. This is determined by linking a primary joint replacement procedure to a subsequent procedure, which typically occurs a number of years later. Therefore, compliance with reporting revision surgical procedures is essential to estimate implant failure rates and the quality of surgical performance more accurately.

Mortality data is collected from Civil Registration data, which is obtained from NHS Digital, and linked to individual patient records within the registry. However, it is important to know that joint replacement is a very successful operation with a very low mortality rate and all surgeons and hospitals have outcomes in line with the expected range.

In FY2020/21, we began a national roll-out of a semi-automated data quality audit process, which enables units to check their data on a monthly, quarterly or annual basis. This has greatly reduced the number of mismatches that have to be checked each time the audit is run, and the pilot suggests this rapidly becomes part of the normal workflow.

We continue to reward hospitals with good data quality as part of our Data Quality Provider Awards Scheme. From FY2023/24, the criteria for the awards will change and we will be offering gold, silver and bronze awards for units who are able to demonstrate good processes to identify and capture NJR procedures, with the highest level of awards being attainable by units who can deliver 100% compliance rates. You can find out more about our award programme here.

To ensure that more historic data anomalies could be addressed in elbow surgery, we have continued working with the British Elbow and Shoulder Society (BESS) and the British Orthopaedic Trainees Association (BOTA) to complete a national manual audit of elbow joint replacement data. This involved surgical trainees reviewing patient records to identify and capture any cases that were seen to be missing from the registry. 

This year, we launched a national data quality audit of shoulder procedures, working with BESS and using the same model as for the elbow audit, to improve the completeness of the dataset to ensure it can be used for outcomes analysis in the future. You can find out more about this here.

Accountability & Transparency model

The monitoring of surgeon, hospital and implant performance outcomes is a key function of our work. The NJR Accountability and Transparency model was developed in 2017 following a root and branch review of the patient safety processes that were already in place.

As part of the initial review, we consulted closely with regulatory and orthopaedic professional bodies and specialty societies. Engagement with the Medicines and Healthcare products Regulatory Agency (MHRA), Care Quality Commission (CQC) and the British Orthopaedic Association (BOA) forms a key part of the model, thus enabling greater patient safety and improved quality of care.

Five-yearly review of the model was commenced in 2022 with a focus on surgeon and unit Standard Operating Procedures. This was driven in part by approaches from the British Association for Surgery of the Knee (BASK) who lobbied for a change in focus in knee reporting to highlight surgeon outliers for total and unicondylar knee replacement rather than their overall practice.

Members of the NJR Surgical Performance Committee and Medical Advisory Committee, both of which include representation from relevant stakeholders, were consulted and were all supportive of the changes to the model.

The principal changes included in the new model are:

  • Introduction of new metrics for total and unicondylar knee replacement to supersede the previous assessment of overall knee practice. Surgeons who are outliers on overall knee will still be reviewed by SPC for a ‘case to answer’ but won’t routinely trigger an alarm
  • Introduction of alarm level notifications on ‘lead surgeon’ metrics where the surgeon hasn’t already received a ‘Consultant in Charge’ notification for that joint and time period
  • Introduction of alert level revision notifications for units, to bring this in line with what we do for mortality
  • Formalisation of re-notification of recurrent and persistent outlier surgeons and units
  • Introduction of a surgeon concern process to ensure that NJR clinicians are able to intervene at an earlier stage where surgeons are significantly upset by the notification

You can find further information on the model here.

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