NJR Developments

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Articles about the benefits of the NJR

To increase public awareness of the work of the NJR, our Board patient representatives, the clinical leadership and NJR Management Team, together with our key contractor staff, reflected on the value that the NJR dataset has brought to joint replacement healthcare, both in the UK and beyond.

We summarised these benefits in a series of articles previously published in the Journal of Trauma and Orthopaedics (JTO). These articles cover the benefits that the NJR provides for each of our stakeholder groups: patients, hospital staff, surgeons, industry, service commissioners, regulators, policy-makers, and broader society, and are also addressed and summarised on the NJR website.

We have continued this focus on NJR benefits work and are currently working towards publishing a number of further articles on our website and in some more mainstream magazines, all based around the theme of joint replacement surgery. Sign up for our newsletter here, to hear more about this work as it progresses.

NJR 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 started to be used for our Annual Report and implant outlier analysis this year.

Both the NJR and EPRD have 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.

We are also working closely with our international colleagues to develop 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, 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 collection forms part of a separate programme, previously managed by NHS Digital (now part of NHSE) and are not routinely collected by the NJR. Until 2023, we had annual access to the cumulative national PROMs data retrospectively, through an application to NHS England’s Data Access Request Service.

Unfortunately, despite multiple discussions with NHSE, we were unable to secure access to useable PROMs datasets during the period 2023-2025. We were therefore extremely disappointed that we were unable to use PROMs to assess knee and hip implant performance in our Annual Reports during this time. We know this has been of concern to many of our stakeholders.

We are now in receipt of an updated file of national PROMs data, and we are assessing the completeness of the records to determine how best to report.

We have on multiple occasions approached NHSE with a business plan making the case for national hip and knee PROMs to be delivered by NJR on behalf of NHSE, in order to better serve the interests of patients and the surgical community. NJR-led delivery would also capitalise on efficiency and cost-savings within this whole outcome environment for NHSE. However, to date we have not been taken up on this offer to deliver National PROMs for the NHS.

Shoulder PROMs data collection is overseen directly by the NJR within our geographical areas of operation and so that service remains uninterrupted, and continuity of analysis and reporting is unimpacted by the halt in the NHSE PROMs data-sharing. We strongly encourage a unified approach to the collection and analysis of all joint PROMs datasets and hope that NHSE will consider this urgently.

Use of PROMs in implant reports: The NJR has routinely included the 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 unavailability of PROMs data from 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%.

Updated December 2025

NJR Supported Research Programme

With such a rich data pool of now well over 4 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:

• Outcomes associated with use of all-polyethylene tibial components
• Trends and outcomes of cement brand usage
• Inequalities in provision and outcomes of joint replacement performed in England
• Outcomes associated with surgeon volumes 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. Researchers seeking to access NJR data may wish to watch the presentations from our NJR Research Webinar.

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. 

During 2023, we undertook a Health Data Research UK (HDR-UK) funded project to map some of our datasets to the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM). This is a standardised vocabulary used in observational datasets worldwide and will allow easier interrogation of international datasets. OMOP mapped datasets are now available to research applicants via the Research Committee.

The NJR now sponsors annual clinical and non-clinical funded research fellowships. For more information see https://www.njrcentre.org.uk/research/research-landing/

NJR 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 have been carried out using the implant scanning tools.

During 2024 we introduced additional functionality for condyle sides in unicondylar knee replacement and for mismatch of manufacturers between glenoid and humeral components in shoulder replacement surgery.

We are continuing to develop the implant scanning tool and have recently commissioned a feasibility exercise to determine whether industry can supply the data to be able to check for sizing mismatches between components of knee constructs.

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. Therefore, we have recently 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.

The MDSv8 changes we introduced 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 now being 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

We are currently working with the British Orthopaedic Oncology Society (BOOS) 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 our future services: NJR Connect – Data Services. The rationale for the implementation of the new IT platform included 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 our newly revised data set launch in June 2023.

We have now moved to a rolling programme of releases of enhancements to the NJR Connect platform. During 2024, these have included new functionality in the NJR implant library, which has enabled surgeons to see a Kaplan-Meier plot for all brands of implants recorded on the registry.

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 some 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 England, 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.

Back 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. Last year, the criteria for the awards changed and we offered gold, silver and bronze awards for hospitals who were able to demonstrate good processes to identify and capture NJR procedures, with the highest level of awards being attainable by those who can deliver 100% compliance rates. We were delighted to award 251 hospitals with a gold award, 49 with a silver and 14 with a bronze level. You can find out more about our award programme here.

During 2024/25, we completed a national data quality audit of shoulder procedures, working with the British Elbow and Shoulder Society (BESS) and the British Orthopaedic Trainees Association (BOTA), using the same model as for the previous year’s elbow audit, to improve the completeness of the dataset to ensure it can be used for a more accurate outcomes analysis in the future. You can find out more about this here. As a result of this audit, we added over 4,990 missed cases to the registry. This is important work ahead of our plans to introduce outlier management of shoulder surgery shortly.

Following the release of minimum data set v8 [MDSv8], we have been able to extend the data quality audit programme to benchmark the new procedures captured by the NJR. Hip hemiarthroplasty and DAIRs procedures have now been introduced with focal knee resurfacing and other non-revision re-operations to follow.

We will also be undertaking a feasibility exercise to determine how best to capture and measure the completeness of non-revision procedures undertaken outside of an operating theatre (e.g. Manipulation Under Anaesthetic (MUA) procedures, performed in hospital emergency departments), as well as work to determine how best to benchmark the collection of periprosthetic fracture fixation.

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.

Our five-yearly review of the model was completed in 2023 with a focus on surgeon and hospital 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.

Within the review, 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

We will shortly be undertaking a similar review of our operating model for managing implant outliers.

You can find further information on the model here.

NJR Patient Network

Our NJR Board patient representatives have always been a vital link in ensuring that NJR decision-making and activity prioritisation is focused upon the best interests of the patient. To ensure patients continue to remain the primary focus of our work, further consideration has been given over this year to how we can enable opportunities for greater patient, carer and public, engagement and involvement, bringing increased awareness of our work.

Through our planning for the re-development of the network and new patient-partnership relationships, we will work towards making the NJR a key source of information, encouraging shared decision-making for those considering joint replacement surgery, by further developing and sharing our resources and by signposting that of other organisations. Delivery of these aims will be through building partnerships to enable the exchange of information with other patient-focused organisations. We are aiming to ensure that new materials and publications are relevant to and widely accessible by all.

Around 40 volunteer members have been recruited to the NJR Patient Network – we’ve seen an excellent response to the communication work around promoting the opportunity externally. The meetings so far this year have included presentations by the chairs of the NJR committees, for which we seek a patient representative to provide the patient voice. We are now following up to give patient members an overview and examples of what their patient input may look like in these committee discussions.

 A key NJR workstream which the network has supported, is with the development of a web-based shoulder risk tool. This work has been undertaken by a team led by Professor Jonny Rees, consultant shoulder surgeon at Oxford, and involved looking at the wording in the tool and helping to develop the front-face.

A prototype of the tool was then presented to our patient members in a further meeting, during which they offered additional feedback on the wording in situ and on the overall appearance of the tool. The developing team felt this provided extremely valuable input for the finalisation of a tool that will hopefully be used by many patients over forthcoming years, once it is available to access through our website.

Whilst the network will continue to add a patient perspective to activities across the full range of NJR workstreams, we’ve also recently addressed the idea of having ‘topic-focused meetings’ whereby patients can hear about a particular NJR activity or expert view on a related topic, and then discuss how it may impact them personally, or patients more generally. We feel there are patients who would value the opportunity to share their perspective and/or experiences related to such activity themes and may then develop these into encouraging case-studies that could be shared on the NJR website to help and inspire others. There has also been some planning to further develop patient-related press stories.

Through further development of our Patient Network, the NJR will be able to extend and promote our range of helpful resources available to past, current and prospective patients, families, carers and the wider public, and aide development of our wider interaction with other patient network groups and agencies to assist us to increase awareness of the work of the NJR and the promotion of the registry more broadly. You can find more information on this on our website here.