NJR component classification

The NJR component database was upgraded to a new implant classification back in 2020, to the classification structure that was agreed upon and developed by NJR and EPRD with industry representation and in many cases required the provision of additional attribute data associated with each implant.

Some suppliers still have to upload their required implant attribute detail and in recognising the importance of this data, we kindly request that those hip and knee implants registered in the NJR component database have all the relevant data uploaded.

Detailed implant data remains of critical importance to the NJR in order to support ongoing analysis and safety monitoring, so we are thankful to those industry representatives who have submitted their component data. The database was further updated in 2025 to allow up to 5 GTINs to be associated with a component catalogue number.

We are pleased to share that we had entered into an agreement with ISAR, so that this classification will also form the basis of the International Prosthesis Library. AdvaMed is supportive of the classification and of registry databases being completed with the required implant attributes. Therefore all industry implant suppliers are requested to check and ensure they populate the new classification with the required implant data.

What is component classification? 

Component classification is a structured way of describing orthopaedic implants using a consistent set of technical characteristics. Rather than identifying an implant only by brand name or catalogue number, component classification methodology groups implants according to their design features, materials and functional characteristics. 

This approach enables implants from different manufacturers to be described in a common language. For example, hip stems can be classified by fixation type, geometry and surface coating, while knee components can be classified by constraint type, bearing surface and fixation method. 

Within the National Joint Registry, component classification provides a standardised framework for describing implant design across the registry’s implant library. It ensures that implants with similar characteristics can be analysed together, regardless of manufacturer or product line. 

Why component classification matters 

The NJR collects large volumes of procedural and implant data. However, meaningful analysis requires more than simply identifying the product used in a procedure. 

Component classification enables the NJR to analyse implants at the level of design features rather than only by brand. This enables: 

• a comparison of implant designs across manufacturers. 
• earlier identification of potential performance issues. 
• more robust research into how design characteristics affect outcomes. 
• clearer reporting of implant performance to clinicians, patients and regulators. 

Classification also supports international collaboration. When registries use compatible classification systems, it becomes easier to combine data and undertake global analyses of implant performance. 

The NJR component classification for hip and knee 

The NJR, working with colleagues from EPRD and ISAR, has developed a detailed classification framework for hip and knee replacement components. The framework was created through collaboration between registry analysts, orthopaedic surgeons, statisticians and international registry partners. 

For hips, the classification captures key design characteristics including: 

• fixation type (cemented, cementless, hybrid) 
• stem geometry and design philosophy 
• bearing surface combinations 
• head size and modularity 
• acetabular component design features 

For knees, the classification includes characteristics such as: 

• level of constraint (cruciate retaining, posterior stabilised, constrained) 
• bearing mobility (fixed or mobile bearing) 
• fixation method 
• component materials and coatings 
• patellar component characteristics 

Each implant recorded in the NJR implant library is mapped to its corresponding classification attributes. This enables outcome analyses to be undertaken both at individual product level and at broader design category level. 

The classification framework is continually updated as new implants enter the market and as implant design evolves. 

The NJR/EPRD/ISAR hip and knee component classification can be seen here.

The NJR component classification for shoulders 

The shoulder classification captures key implant design characteristics across the main types of shoulder surgery, including: 

• anatomical shoulder replacements 
• reverse shoulder replacements 
• hemiarthroplasty designs 

The NJR/EPRD/ISAR shoulder classification can be seen here 

Licensing the NJR component classification 

The NJR component classification is available for use by other registries and organisations through a licensing arrangement. 

Licensing the classification enables registries to adopt a mature and well-tested framework for describing implant design without needing to develop their own system from first principles. It also supports greater international alignment in how implants are described and analysed. 

Organisations interested in licensing the NJR component classification should contact the NJR to discuss: 

• the scope of use 
• implementation requirements 
• data mapping and integration 
• licensing arrangements 

Adopting a shared classification framework supports more effective international research collaboration and improves the comparability of registry analyses. 

Working with industry 

Accurate classification depends on detailed and reliable technical information about implants. The NJR works closely with implant manufacturers to ensure that components recorded in the registry can be classified correctly. 

Providing this information ensures that implants are classified accurately and consistently within the NJR implant library. This supports robust analysis of implant performance and contributes to improved patient safety. 

The NJR encourages manufacturers to engage early when new implants are introduced so that classification can be completed before widespread clinical use. 

Access to the NJR Component Database is available in Supplier Feedback services via NJR Connect (see the link on the left side of this page). 

Some suppliers still have to upload their required implant attribute detail and in recognising the importance of this data, we kindly request that those hip and knee implants registered in the NJR component database have all the relevant data uploaded.

Detailed implant data remains of critical importance to the NJR in order to support ongoing analysis and safety monitoring, so we are thankful to those industry representatives who have submitted their component data. The database was further updated in 2025 to allow up to 5 GTINs to be associated with a component catalogue number.

We are pleased to share that we had entered into an agreement with ISAR, so that this classification will also form the basis of the International Prosthesis Library. AdvaMed is supportive of the classification and of registry databases being completed with the required implant attributes. Therefore all industry implant suppliers are requested to check and ensure they populate the new classification with the required implant data.

Uploading implant classification details

Completion of the new classification enables us to provide several additional reporting opportunities and other benefits including additional analysis. This includes those outlined below:

• Enhancement of NJR Supplier Feedback will enable greater analysis opportunities within NJR reporting services. Some examples of this include:
  • Differentiation of the types of polyethylene, such as highly cross-linked polyethylene and conventional polyethylene.
  • The ability to compare similar devices based on additional layers of attribute data, such as materials and coatings.
• Regulatory requirements (EU MDR):
  • The granularity of the classification supports device manufacturers with EU MDR requirements by permitting the NJR to produce standard reports at the appropriate variant level, rather than brand-level reporting.
• Facilitates Registry classification harmonisation
  • Supports medical device manufacturers with global registry requirements for ongoing harmonisation efforts between global registries to utilise the same implant classification structure by easing the burden of multiple registry data entries. The classification structure is supported by ISAR.

It is imperative that implants that are registered in the NJR Component Database include all relevant data. We will now report exclusively against the new classification structure for all Supplier Feedback outputs – including both reports and data files. The quality of reporting that we are able to provide is dependent on the quality of the data that has been added by implant suppliers.

NJR Supplier Feedback

• Comparative analysis is subject to all manufacturers providing data used to group implants. The new classification permits additional options around grouping devices differently for comparative analysis which may not be feasible with missing data due to the exclusion of NJR records in such cases.
• Future report enhancements based on a new range of possibilities will not be available for implants missing data.

Regulatory requirements (EU MDR):

• Standard NJR report production methodology changes could be limited and the reports might not be produced in a MDR ready format, e.g. construct/variant level reporting would be based on NJR implant characteristics at a more granular level.

Please share this information widely within your organisation as appropriate. For all enquiries and for support relating to this matter, please contact Edward Caton at: edward.caton@necsws.com