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Shoulder implant data collection on the National Joint Registry
Jaime Candal-Couto, Simon Robinson, David Hawkes, David Miller and Derek Pegg
The National Joint Registry (NJR) started collecting shoulder implant data in April 2012, nine years after the NJR was established, when it was originally only collecting data on hip and knee implants.
This article looks at and summarises key findings from the 21st NJR Annual Report –shoulder section1, highlights how registry data can inform contemporary shoulder replacement surgery (SRS), and the potential opportunities that future evaluation of NJR data may bring.
Since 2012, the NJR has collected a total of 98,334 shoulder replacement procedures, made up of over 89,172 primary and 9,106 revision procedures (Table 1). This provides a wealth of high-quality data that is complete and mature enough to help guide a surgeon in providing the best outcomes for their patient.
Data quality
Data quality is the foundation on which any conclusions and research are based. Table 2 shows the compliance for shoulders since 2018. The NJR is constantly striving to maximise data capture. Since 2020, the NJR requires hospitals to participate in an ongoing automated data quality audit and as a result captures over 97% of implants across all joints. However, in the early years, shoulder compliance was not as robust. The NJR has identified 15,504 shoulder procedures performed in England between 2012 and 2020 which are recorded in HES (Hospital Episode Statistics) but not in the NJR. A data quality audit is currently being undertaken, involving all affected hospitals and over 4,000 additional shoulder procedures have been added to the NJR so far.
Additionally, the NJR has moved to whole construct validation, ensuring that all relevant elements required to build a construct are present in a procedure. This has led to the definition of unconfirmed constructs, where there are insufficient implants listed to complete a construct or the implants do not match the reported procedure.
Currently, a total of 7,113 (9.6%) shoulder procedures are unconfirmed and the NJR is working on a process of checking and validation of these constructs.
COVID-19 effect still evident
Figure 1 illustrates how elective SRS volumes reduced in 2020 because of the COVID-19 pandemic, but by the end of 2023 had recovered to 2019 volume. However, pre-pandemic there had been a year-on-year increase in volumes recorded. It would therefore suggest that the pandemic deficit continues to impact. The graph also demonstrates that NHS elective SRS activity in NHS hospitals is still noticeably below pre-pandemic levels, while activity in independent hospitals has risen for both independent and NHS-funded surgery.
Primary shoulder replacement
Since 2012, there have been substantial changes in the different indications for SRS as well as the implants used. Currently, the NJR collects data for 12 different indications for surgery, 60% of cases being osteoarthritis, 25% cuff tear arthropathy and 14% acute trauma. Eight main different procedure types are noted, see Figure 2. Data is also acquired as regards fixation with or without cement, patient specific instruments and computer guided surgery. Therefore the data is very heterogenous, indicating it will take time to collect sufficient cases to be meaningful for some particular procedure types. This highlights the importance of on-going reliable and robust data collection.
Traditionally, anatomical constructs (either anatomical total shoulder replacement or hemiarthroplasty) were used to treat conditions such as osteoarthritis, inflammatory arthritis and acute fractures. Reverse polarity total shoulder replacements were initially introduced, very successfully, to treat patients with arthritis and rotator cuff deficiency where the anatomical implants did not perform well. However, the success of reverse shoulder replacements has led to a progressive expansion of its indications across all other different diagnosis including to patients with rotator cuff tears and no arthritis. The NJR has recorded this evolution in shoulder replacement practice since 2012.
Figure 2 demonstrates the progressive decline in the use of anatomical implants, particularly hemiarthroplasties, and how stemmed reverse polarity shoulder replacements have increasingly become by far the commonest shoulder procedure recorded in the NJR. This figure also demonstrates that stemless anatomical replacements are becoming more popular than the traditional stemmed ones, and that high volume surgeons tend to prefer the use of reverse polarity implants while hemiarthroplasties are performed mostly by low-volume surgeons. (Please note the difference in scale of the y-axis between each sub-plot, for both Figures 2 and 3).
Hemiarthroplasty vs reverse total shoulder in trauma
Figure 3 demonstrates how stemmed humeral hemiarthroplasty (HHA) volumes for acute trauma have declined while stemmed reverse total shoulder replacement (RTSR) have steadily risen and are more commonly used by higher volume surgeons.
Revision outcomes in different shoulder constructs in elective surgery
Figure 4 shows KM estimates for cumulative revision rates of the various shoulder constructs, on the NJR, used in elective SRS. The performance of stemmed conventional total shoulder replacement compared to stemmed reverse polarity shoulder replacements is of interest. Reverse polarity total shoulder replacements tend to have an initially higher revision rate which then plateaus, whereas the conventional total shoulder replacements increase more slowly but at a constant rate and therefore exceed the cumulative risk of revision of reverse polarity total replacements and overall is 1.8% higher at 11 years. A failed reverse polarity TSR has historically had limited revision options, and therefore having revision as an end point may under report the true incidence of failure.
The extent to which the different indications for surgery are confounding results is not clear and results should be interpreted cautiously. Caution should be taken when interpreting subgroup outcomes and highlights the importance of comprehensive PROMs data, that would provide a much greater assurance when attempting to differentiate superior outcomes from one type of implant construct to another.
PROMs
From the initial collection of shoulder implant data by the NJR, shoulder surgeons felt it was important to directly collect information on PROMs. This is unique to shoulder implants on the NJR and adds a more sophisticated assessment of success than the current standard outcome analysis for all other implants, where revision and mortality outcomes are used exclusively.
PROMs data are captured and held by NHS England for hip and knees but this has been unavailable to the NJR for over two years. Shoulder PROMs are collected directly by the NJR. While pre-operative PROMs collection for SRS, is excellent for some hospitals, others have struggled. This is obviously a missed opportunity to facilitate a more comprehensive assessment of both implant outcome and hospital services. For the last decade the British Elbow and Shoulder Society (BESS) have consistently advocated the use of shoulder PROMs as essential in the assessment of patient outcomes and surveillance after SRS. We would strongly encourage the collection of pre-operative PROMs. This is mandated by the NHS Standard Contract but many hospitals have generally poor returns, with fewer than 30% of elective patients having their pre-operative PROMs data submitted.
PROMs information is available in the NJR annual report relating to shoulder implants [1]. It is evident that hemiarthroplasties have a significantly poorer outcome than other constructs but, interestingly, anatomical total shoulder replacements are marginally superior to the commoner reverse polarity implants. However, due to current suboptimal PROMs completeness, there must remain some caution in drawing firm conclusions at this stage.
Minimum volume improves outcome
Research by Valsamis et al. [2] suggests that the minimum volume sweet spot for a shoulder replacement surgeon to be able to deliver better outcomes, would appear to be a mean of 10.4 procedures per year. This is illustrated in Figure 5 which presents a multilevel parametric survival model of hazards ratio against mean annual consultant volume, adjusted for key confounding factors. This paper illustrates how analysis of NJR shoulder data can guide surgeons and health systems into achieving the most reliable outcomes for patients.
The current NJR research programme includes evaluating outcomes associated with operationtype in shoulder surgery.
Research and future developments
Ongoing NJR supported research, includes a new prediction model, which incorporates NJR, Hospital Episode Statistics (HES) and Danish Shoulder Arthroplasty Registry (DSR) data. This aims to inform patients of their risks of having shoulder replacement surgery. A recent paper by Valsamis et al. [3] suggests that such a model will be a powerful tool for both patients and surgeons in making informed decisions during the consent process for shoulder surgery, on an individual basis.
The current NJR research programme includes evaluating outcomes associated with operation-type in shoulder surgery.
There are currently five shoulder-specific ongoing research projects that have been approved by the NJR Research Committee. These will evaluate the health and economic outcomes related to the increasing use of reverse shoulder replacement; examine mortality following reverse shoulder replacement; review a stemless prosthesis used in anatomic total and hemiarthroplasty; investigate complication rates and mortality after elective and acute shoulder and elbow replacements; and implement computer adaptive testing for the Oxford Shoulder Score. The NJR encourages the use of the registry dataset to answer research questions that add value to our knowledge about joint replacement practice, clinical performance, cost-effectiveness and patient safety.
More information can be found on the NJR website www.njrcentre.org.uk/research/ research-requests.
Annual Clinical Reports (ACR) for hospitals and Consultant Level Reports (CLR)
Finally, the NJR will soon be able to provide shoulder replacement surgeons with a more detailed analysis on the outcomes of the units in which they work. As well as their own personal reports of their surgical outcomes compared to those of their peers, just as hip and knee surgeons currently receive. If the pre-operative PROMs data capture improves the overall analysis of surgical performance it will be a rich source of reference enabling advancement to ultimately improve patient outcomes.
Summary
• The NJR approaches 100,000 shoulder procedures since 2012.
• The COVID-19 pandemic continues to have affected provision of shoulder replacement surgery.
• Observed trends show a greater use of reverse total shoulder replacements.
• Evidence suggests a critical minimum volume for a surgeon, each year, is 11.
• The collection of PROMs data can be crucial in differentiating sustained and successful outcomes from the variety of shoulder replacement constructs currently in use.
Acknowledgement
We are grateful to all patients, surgeons and healthcare staff for sharing data with the NJR. NEC Software Solutions (UK) provide secure data capture for the registry, University of Bristol undertook the analysis that was published in the NJR Annual Report. A full list of authors of the NJR Annual Report is available at https://reports.njrcentre.org.uk.
References
1. National Joint Registry. NJR 21st Annual Report 2024 – Shoulder Section. Available at: https://reports.njrcentre.org.uk
2. Valsamis EM, Collins GS, Pinedo-Villanueva R, et al. Association between surgeon volume and patient outcomes after elective shoulder replacement surgery using data from the National Joint Registry and Hospital Episode Statistics for England: population based cohort study. BMJ. 2023;381:e075355.
3. Valsamis EM, Jensen ML, Coward G, et al. Risk of serious adverse events after primary shoulder replacement: development and external validation of a prediction model using linked national data from England and Denmark. Lancet Rheumatol 2024;6(9):e607-e614.
