Executive summary (across all report areas)

Part Four: Implant- and unit-level activity and outcomes 2018

Part Four of the annual report gives performance and data entry quality indicators for Trusts and Local Health Boards (many of whom comprise more than one hospital) and independent (private) providers in England, Wales, Northern Ireland and the Isle of Man for the 2018 calendar year. Outcomes analysis after hip and knee replacement surgery is also provided for the period 2009 to 2019.

This section now also provides data for implant outliers since 2003 and further information on notification and last usage date.

The full analysis for units can be found in the Part Four online document which is available in the downloads section at reports.njrcentre.org.uk

4.1 Implant performance

The Implant Scrutiny Committee reports Level 1 outlier implants to the MHRA. Since the committee’s formation in 2009 there have been four hip stems, nine hip acetabular (cup) components and 28 hip stem/cup combinations reported. Seven knee brands have been notified.

An implant is considered to be a Level 1 outlier when its Prosthesis Time Incident Rate (PTIR) is more than twice the PTIR of the group, allowing for confidence intervals. These are shown as the number of revisions per 100 prosthesis-years. As of March 2015, we have started to identify the best performing implants, these would have a PTIR less than half that of their group, allowing for confidence intervals. To date no implants have reached that level.

Components and constructs previously reported to MHRA, but no longer at Level 1, are not listed.

Hip implant performance

Table 1 Level 1 outlier stems/femoral components reported to MHRA. Table 2 Level 1 acetabular components reported to MHRA.Table 3 Level 1 outlier stem/cup combinations. Best performing hip implants

There are no hip implants or combinations performing statistically less than half their expected PTIR.

Knee implant performance

Table 4 Level 1 outlier implants reported to MHRA. All of these implants have been discontinued.

Best performing knee implants

There are no knee implants performing statistically less than half their expected PTIR.

4.2 Clinical activity

Overall in 2018, 145 NHS Trusts and Local Health Boards (comprising 250 separate hospitals) and 181 independent hospitals were open and eligible to report patient procedures to the NJR All units except for two NHS trauma units and one newly opened independent unit submitted data in 2018. The proportion of all hip and knee joint replacements entered into the NJR compared to those entered in HES, is only available by NHS Trust. No data on this is currently available from private providers and figures also exclude units in Northern Ireland as compliance data is not available. Unfortunately finalised compliance figures for Local Health Boards in Wales were not available at time of publication.

• 56.7% of NHS providers reported 95% or more of the joint replacements they undertook
• 30.6% of NHS providers reported between 80% and 95%
• 12.7% of NHS providers reported less than 80%

Of those hospitals submitting data, the proportion of patients who gave permission (consent) for their details to be entered into the NJR were:

NHS hospitals

• 41.1% of NHS hospitals achieved a consent rate of greater than 95%
• 37.9% achieved a consent rate of 80% to 95%
• 21.0% recorded a consent rate of less than 80% 

Independent hospitals

• 63.3% of independent hospitals achieved a consent rate greater than 95%
• 28.3% achieved a consent rate of 80% to 95%
• 8.3% recorded a consent rate of less than 80%

There has been a drop in recorded consent for all submitting units when compared to the previous year, with those achieving a higher than 95% rate falling from 55% to 50%. The proportion of all units achieving a higher than 80% consent rate remains consistent and fell by only 1% to 84% in 2018. 

Similarly, the proportion of entries in which there is significant data to enable the patient to be linked to an NHS number (linkability) are listed.

NHS hospitals

• 83% achieved a proportion of patients with a linkable NHS number greater than 95%
• 15% achieved a proportion of 80% to 95%
• 2% recorded a proportion of less than 80%

Independent hospitals

• 77% achieved a proportion of patients with a linkable NHS number greater than 95%
• 17% achieved a proportion of 80% to 95%
• 6% recorded a proportion of less than 80%

There has been a drop in linkability from 2017 with the percentage of submitting units achieving over 95% in 2018 falling from 85% to 81%. The proportion achieving a greater than 80% linkability rate is relatively consistent with an overall drop of 1% in 2018.

Note: Independent hospitals might be expected to have lower linkability rates than NHS hospitals, as a proportion of their patients may come from overseas and do not have an NHS number.

4.3 Outlier units for 90-day mortality and revision rates for the period 2009 to 2019

The observed numbers of revisions of hip and knee replacements for each hospital were compared to the numbers expected, given the unit’s case-mix in respect of age, gender and reason for primary surgery. Hospitals with a much higher than expected revision rate for hip and knee replacement have been identified. These hospitals had a revision rate that was above the upper of the 99.8% control limits (these limits approximate to +/-3 standard deviations). We would expect 0.2% (i.e. one in 500) to lie outside the control limits by chance, with approximately half of these (one in 1,000) to be above the upper limit.

When examined over the past ten years of the registry, a total of 39 hospitals reported higher than expected rates of revision for knee replacement, and 26 hospitals had higher than expected rates of revision for hip surgery. However, revisions taken only from the last five years of the registry showed only 18 hospitals reporting higher than expected rates for knees, and ten for hips.

The 90-day mortality for primary hip and knee replacement was calculated using the last five years of data for all hospitals by plotting standardised mortality ratios for each hospital against the expected number of deaths.  No hospitals had higher than expected mortality rates for either hip or knee replacement.

Note: The case mix for mortality includes age, gender and ASA grade. Trauma cases have been excluded from both the hip and knee mortality analyses together with hips implanted for failed hemi-arthroplasty or for metastatic cancer (the latter only from November 2014 when recording of this reason began). Also, where both left and right side joints were implanted on the same day, only one side was included in the analysis.

Note: Any units identified as potential outliers in Part Four have been notified. All units are provided with an Annual Clinical Report and additionally have access to an online NJR Management Feedback system.

Important note about the outlier hospitals listed

In earlier annual reports, the NJR reported outlying hospitals based on all cases submitted to the NJR since 1 April 2003. To reflect changes in hospital practices and component use, the NJR now reports outlying hospitals based on the last ten years (13 February 2009 to 14 February 2019) and five years of data (13 February 2014 to 14 February 2019 inclusive, the latter date being when the dataset was cut). These cuts of data exclude the majority of withdrawn outlier implants and metal-on-metal total hip replacements from analysis, and thus better represent contemporary practice.

Outliers for Hip mortality rates since 2014²

None identified

Outliers for Knee mortality rates since 2014²

None identified

Outliers for Hip revision rates, all linked primaries from 2009¹

Ashtead Hospital (Surrey)
Basingstoke and North Hampshire Hospital
BMI Clementine Churchill Hospital (Middlesex)
BMI Esperance (East Sussex)
BMI The Meriden Hospital (West Midlands)
Clifton Park Hospital (North Yorkshire)
Fitzwilliam Hospital (Cambridgeshire)
Homerton University Hospital
KIMS Hospital (Kent)
Milton Keynes Hospital
Musgrove Park Hospital
North Downs Hospital (Surrey)
Northampton General Hospital (Acute)
Nuffield Health Brighton Hospital (East Sussex)
Ormskirk and District General Hospital
Prince Charles Hospital
Salisbury District Hospital
Shepton Mallet Treatment Centre (Somerset)
Southampton General Hospital
Spire Southampton Hospital (Hampshire)
St Richard's Hospital
Sussex Orthopaedic NHS Treatment Centre
Wansbeck Hospital
Watford General Hospital
Weston General Hospital
Wrexham Maelor Hospital

Outliers for Hip revision rates, all linked primaries from 2014²

BMI Bishops Wood Hospital (Middlesex)
Fitzwilliam Hospital (Cambridgeshire)
Milton Keynes Hospital
Nuffield Health Cheltenham Hospital (Gloucestershire)
Ormskirk and District General Hospital
Southampton General Hospital
Spire Hartswood Hospital (Essex)
St Richard's Hospital
Wansbeck Hospital
Weston General Hospital

Outliers for Knee revision rates, all linked primaries from 2009¹

Ashford Hospital
Basingstoke and North Hampshire Hospital
BMI Bishops Wood Hospital (Middlesex)
BMI Goring Hall Hospital (West Sussex)
BMI Princess Margaret (Berkshire)
BMI The London Independent Hospital (Greater London)
BMI The Meriden Hospital (West Midlands)
Broadgreen Hospital
Charing Cross Hospital
County Hospital Louth
Diana Princess of Wales Hospital
Ealing Hospital
Grantham and District Hospital
Guy's Hospital
Heatherwood Hospital
Hinchingbrooke Hospital
Homerton University Hospital
Horton NHS Treatment Centre (Oxfordshire)
King Edward VII Hospital Sister Agnes (Greater London)
Llandough Hospital
Nevill Hall Hospital
New Hall Hospital (Wiltshire)
Nottingham City Hospital
Nuffield Health Chichester Hospital (West Sussex)
Peterborough City Hospital
South Tyneside District Hospital
Southampton General Hospital
Southampton NHS Treatment Centre (Hampshire)
Southmead Hospital
Spire Hull and East Riding Hospital (East Yorkshire)
Spire Southampton Hospital (Hampshire)
St Albans City Hospital
St Mary's Hospital
St Richard's Hospital
Sussex Orthopaedic NHS Treatment Centre
University College Hospital
University Hospital Aintree
West Cumberland Hospital
York Hospital

Outliers for Knee revision rates, all linked primaries from 2014²

Barlborough NHS Treatment Centre (Derbyshire)
BMI Bath Clinic (Avon)
BMI The Meriden Hospital (West Midlands)
BMI The South Cheshire Private Hospital (Cheshire)
Guy's Hospital
Heatherwood Hospital
King Edward VII Hospital Sister Agnes (Greater London)
Leighton Hospital
Lister Hospital
Nuffield Health Chichester Hospital (West Sussex)
Southmead Hospital
Spire Hull and East Riding Hospital (East Yorkshire)
Spire Southampton Hospital (Hampshire)
Springfield Hospital (Essex)
St Mary's Hospital
St Richard's Hospital
Sussex Orthopaedic NHS Treatment Centre
Winfield Hospital (Gloucestershire)

4.4 Better than expected performance

This year we have again listed hospitals where revision rates are statistically better than expected. The lists here show units that lie below the 99.8% control limit which also achieved greater than 90% compliance in the 2015/16 NJR data quality audit. Units with lower data quality compliance are automatically excluded from these lists.

Better than expected for Hip revision rates, all linked primaries from 2009¹

Calderdale Royal Hospital
Emersons Green NHS Treatment Centre (Avon)
Ipswich Hospital
Luton and Dunstable Hospital
Musgrave Park Hospital
Nuffield Health Derby Hospital (Derbyshire)
Nuffield Health Exeter Hospital (Devon)
Queen Alexandra Hospital
Queen’s Hospital Burton Upon Trent
Queens Medical Centre Nottingham University Hospital
Royal Derby Hospital
Royal Devon and Exeter Hospital (Wonford)
Royal Stoke University Hospital
Royal Surrey County Hospital
Russells Hall Hospital

Better than expected for Hip revision rates, all linked primaries from 2014²

BMI Alexandra Hospital Cheadle (Cheshire)
Calderdale Royal Hospital
Emersons Green NHS Treatment Centre (Avon)
Ipswich Hospital
Musgrave Park Hospital
Royal Devon and Exeter Hospital (Wonford)
Royal Surrey County Hospital

Better than expected for Knee revision rates, all linked primaries from 2009¹

Bishop Auckland Hospital
BMI Priory Hospital (West Midlands)
City Hospital
Colchester General Hospital
Hexham General Hospital
Ipswich Hospital
Musgrave Park Hospital
Norfolk and Norwich Hospital
North Tyneside General Hospital
Nottingham Woodthorpe Hospital (Nottinghamshire)
Nuffield Health Derby Hospital (Derbyshire)
Nuffield Health Ipswich Hospital (Suffolk)
Princess Alexandra Hospital
Royal Derby Hospital
Stepping Hill Hospital
Worcestershire Royal Hospital
Wrightington Hospital

Better than expected for Knee revision rates, all linked primaries from 2014²

Hexham General Hospital
Musgrave Park Hospital
Stepping Hill Hospital

Note:
¹ Date range 13 February 2009 to 14 February 2019 inclusive.
² Date range 13 February 2014 to 14 February 2019 inclusive.

 

 

 

 

 

 

 

Part Three: Outcomes after joint replacement 2003 to 2017

Part Three of the 16th Annual Report provides outcome data in relation to hip, knee, ankle, shoulder and elbow replacements. It describes activity between 1 April 2003 and 31 December 2018.

There were 2,766,764 procedures entered into the NJR across all joint types, performed up to 31 December 2018. After removing procedures without linkage identifiers and those procedures where the linkage was not sufficiently clear to allow their use, there remained 2,332,798 primary cases and 66,248 linked revisions. This represents over a quarter of a million new cases being registered during the year.

There were 1,091,892 primary total hip replacements, 1,193,830 knee replacements, 5,587 ankle replacements, 37,916 shoulder replacements and 3,573 elbow replacements available for analysis, and these form the basis of the ensuing section concerning clinical outcomes, including revision rates, mortality data and other clinical outcomes where these are collected.

As previously, some figures in the latest year may not yet fully represent the final figures. There may be late data entry by units and further correction after the data quality audit and for this reason, readers should be wary of drawing conclusions about apparent sudden increases or decreases in a particular procedure in the latest year compared to previous years.

Hip replacement procedures

The number of hip replacement procedures recorded in the NJR continues to grow at a few percent per year continuing the pattern over the last decade since data entry became consistent at around 95% after the initial few years of “start-up”.

The steady gentle decline in cemented and uncemented hips since 2012 continues in favour of hybrid fixation. Few cemented hips have anything other than metal-on-polyethylene (MoP) or ceramic-on-polyethylene (CoP) bearings and the steady decline of MoP in favour of CoP continues. Likewise, those using hybrid hips appear to be increasingly favouring CoP. The consistent and dramatic decline (since 2011) in the use of ceramic-on-ceramic (CoC) bearings in favour of CoP bearings for uncemented hips continues. These combinations are used more in younger patients and this change to CoP is likely related to the excellent survivorship of this bearing surface combination as highlighted in previous years’ reports.

Metal-on-metal (MoM) bearings have declined to a trickle, and the brief burst of interest in ceramic-on-metal (CoM) bearings several years ago appears to have lapsed almost completely.

As with knee replacement, primary hip revision rates have declined steadily but progressively since about 2008, with this change being even more obvious for hips than for knees. In hips, this has often been attributed to the rapid decline in MoM usage and this has no doubt been a significant factor. However, the fact that we see a similar decrease in revision rates for knee replacements indicates that we need to look for alternative explanations for this improvement. It seems that the progressive decline in revision rates does coincide closely with the time at which the NJR began to provide personal revision rate feedback to surgeons. It is therefore likely that at least some element of the improvement in revision rates has come about due to the feedback of surgeons’ own audited results, and the actions that they have taken in response to this information.

The generally low revision rates for CoP and CoC bearing surfaces in primary hip replacement are quite striking features of the data relating to many of the sub-groups regardless of age and gender, but applies particularly to the younger age groups.

It is interesting to note that in cemented THR the CoP failures occur at a similar rate to MoP at 15 years despite the fact that up to 13-14 years the CoP combination fares slightly better. This observation is largely due to the small numbers of cases available for analysis at 15 years, meaning that less reliance can be placed upon the figures at that time point. This difference at 14-15 years may also relate in part to the fact that 14 years ago far fewer highly cross-linked polyethylene implants were being used, compared to the use over the last ten years; that change was a gradual one though and would, therefore, be unlikely to have produced any sudden change in failure rates.  For uncemented THR the difference between MoP and CoP is similar. However, the failure rate of CoC splits the difference between MoP and CoP. Overall the variability of performance of different bearing surfaces within uncemented hips varies widely. Notably, CoP has slightly lower revision rates out to 13-14 years.

The pattern of differences in hybrid hip replacement also persists. With CoP bearings having lower revision rates when compared to other bearing types at 13-14 years, after which the numbers in these groups becomes small and therefore estimates are less reliable.

The large variability in revision rates with age is seen once again. Females under 60 years of age have higher revision rates than their male counterparts whereas those over the age of 60 have lower revision rates.  Once MoM total hips and resurfacing hips are excluded however, the markedly higher revision rates in females under the age of 60 is not observed but revision rates remain lower in females over this age.

Knee replacement procedures

The analysis is now based on 1,193,830 primary knee replacements and there are 33,292 linked revisions from these primary operations. Amongst these primary numbers, there has been a slight increase in the proportion of unicompartmental knees, as has already been seen in the past five years.  The continuing decline in hybrid, uncemented and patellofemoral knee operations means that these each represents really quite small numbers each year. There are some surgeons performing multiple partial replacements in the same knee in moderate numbers individually, but the overall numbers are currently insufficient to derive much useful information from analysis.

Overall revision rate for knees during the last 15 years appeared to alter from around 2008, such that 1-year revision rates peaked in 2009, 3-year rates peaked in 2011, 5-year rates peaked in 2013, 7-year rates peaked in 2015 and 10-year revision rates were highest in 2018.  As discussed for hip replacement, this series of alterations and their timing implies some significant change in about 2008 which has had a knock-on effect on revision rates for procedures from that time onward. This is also seen to be the case for hips and although more dramatic in hips due to the additional effects of the decline in MoM hip bearings from a similar time, there is still clearly another factor at work because knees are affected as well as hips. Again, it is possible this could result from the NJR providing feedback to surgeons; a process which commenced in 2008. 

The results show that posterior-stabilised fixed-bearing, posterior-stabilised mobile-bearing, unconstrained mobile-bearing and constrained condylar TKRs all seem to have slightly (but significantly) higher failure rates than unconstrained fixed-bearing cemented TKRs. The difference in failure rate between (uncemented/hybrid) posterior-stabilised and unconstrained TKRs is increasing year on year. This difference, which is also seen in data from other registries, has sometimes been attributed to the selective use of some of these more constrained implants for more complicated cases. This would be a plausible explanation for why constrained condylar implants might have a higher failure rate in primary cases, as they would not be used without good reason, as they are more complicated to use, more expensive and potentially have additional sources of post-operative complications. This explanation probably does not hold water in the case of posterior-stabilised or mobile-bearing TKRs however, as these are mostly selected by surgeons as a matter of choice (because they prefer them in principle) and they, therefore, use them routinely regardless of the patient’s specific characteristics.

It is interesting to note that the observed difference in revision rates between cemented unconstrained mobile-bearing TKR and cemented unconstrained fixed-bearing TKR is not seen for these bearing options in the uncemented/hybrid TKR groups. This lack of difference is being driven by the higher absolute failure rate of uncemented/hybrid unconstrained, fixed bearing. In contrast, the higher revision rate for fixed bearings in cemented posterior-stabilised TKRs becomes even more apparent in uncemented posterior-stabilised knees.

Considering the higher revision rate of primary unicompartmental knees that is seen across the 15 years of NJR data, it is of interest to see that up to 12 years the re-revision rate for unicompartmental knees that have been revised is lower in the NJR data compared to the re-revision of revised primary TKRs. This difference is small and the number at risk beyond seven years is low so the observation should be considered cautiously in light of the fact that the “first revision” of unicompartmental knees contains a mix of procedures ranging from simple bearing exchange in non-infected cases to full revision using a “revision” type of TKR.

The re-revision rate of revised primary patellofemoral joints is seen to be substantially lower in relation to the re-revision rate of primary total knees and of unicompartmental knees. Since first-revision of patellofemoral replacements is a less diverse procedure this lower re-revision rate is much more likely to be real than the more modest difference seen for unicompartmental knees. However, it is important to balance the survivorship of the revision against the likelihood of revising the primary.

Ankle replacement procedures

Ankle replacements have only been entered into the NJR since April 2010, and the numbers remain relatively small compared to hips, knees and shoulders.  Nevertheless, the number of primary cases in the NJR rose by 843 during the year to reach 5,587, which now represents a very large cohort.

There have been 265 revision operations on these procedures, which include 37 conversions to arthrodesis. Unfortunately, the collection of data about arthrodesis and amputation as a “revision” outcome of ankle replacement is known to be incomplete in the NJR data. There may also have been a misunderstanding by some surgeons about whether those procedures are supposed to be registered as revision procedures by the completion of an A2 Minimum Dataset form and submission to the NJR. However, the mandatory reporting requirements and NJR definition of a revision are clear that the definition of revision does include any case where a component of an arthroplasty is either removed, modified or added at a subsequent procedure.

Since amputation is commonly performed by vascular surgeons in the UK, this may also have led to difficulties with the completeness of data since those surgeons are not within orthopaedic units and may not be familiar with the NJR and the mandatory reporting requirements. Analysis of data for failure rates and reasons for failure of ankle replacement therefore remains difficult and potentially inaccurate compared to some other joints. The overall revision rates for ankle replacement still need to be interpreted with caution.

It is clear that ankle replacement is being performed predominantly in male patients and that the overwhelming majority of those being registered involved uncemented implants. The numbers of ankle replacements being performed by each surgeon are remarkably similar to the numbers being performed by each unit where they are done, suggesting that surgeons have generally already selected one amongst their number in each unit to perform these procedures.

Notwithstanding the difficulties outlined above with respect to interpreting the data, it seems clear that the main reason for revision in these joints has been loosening of either the talar component, the tibial component or both. The rate of revision for infection must be interpreted with particular caution as that could be a failure mode which might particularly be expected to result in arthrodesis or amputation rather than revision surgery.

The comparative results of different implants and implant types are currently also difficult to interpret with confidence, not least because the most popular implant was voluntarily removed from the market by the manufacturer in 2014, and in the same year a quite different implant was introduced and immediately became the best-selling implant. This latter implant has a very short-term follow-up in the NJR despite the high numbers implanted.

Elbow replacement procedures

This section relates to radial head replacement, distal humeral hemiarthroplasty and total elbow replacement. As with ankle replacement, the numbers are relatively small compared with hips and knees, but the 3,573 cases still represent a substantial cohort of elbow replacements.

In contrast to some other joints, a large proportion of elbow replacements are performed for acute trauma, with this indication accounting for over 35% of the total. The trauma cases also differ significantly from the elective cases in terms of the type of implant used. In trauma, radial head replacement and distal humeral hemiarthroplasty make up over half the cases, whereas 90% of elective cases are total elbow replacement. Female patients make up 70.6% of cases.

The great majority of revision cases being entered into the NJR have been from primary cases performed before elbow replacements started to be included in the NJR in April 2012.

The number of surgeons entering primary elbow cases into the NJR has diminished slightly over recent years and the number entering revision cases were far fewer during 2018 than over the whole of the previous five years. This may reflect professional advice that elbow replacements are best concentrated in a small number of sites and surgeons so as to increase individual experience.

The majority of elective elbow replacements are still performed for inflammatory arthropathy.

The likelihood of having a revision elbow replacement is substantially higher during the first five years after elective replacements than after replacement for trauma (7.4% vs 3.0%). This could be for a number of reasons but it is important to note the very different spectrum of procedures being compared. At present, the numbers in the database do not allow for stratification and subset analysis to allow the reasons to be fully analysed by gender, age or individual procedure type.

Mortality after elbow replacement is seen to be 16.5% at five years and appears higher in trauma vs elective cases (19.8% vs. 15.2%) though the extent to which this is simply a manifestation of the mean ages is not yet clear.
 
Shoulder replacement procedures

Shoulder replacements began being registered in NJR in April 2012, and since that time 37,916 primary operations are available for analysis.  Of these, 1,158 have undergone a revision operation.

Female patients accounted for 70.5% of shoulder replacements. There has been a quite dramatic change in the type of procedure being performed on the shoulder in recent years such that in 2018, 57% of all such operations were reverse polarity shoulders, which represents a 16% increase since 2015. Conventional shoulder replacements seem to be holding a fairly steady rate of implantation while humeral hemiarthroplasty is declining in numbers.

Relatively large numbers of surgeons appear to be performing shoulder replacements (722 surgeons in 395 units) considering the numbers being done overall. Consequently, the numbers performed by each surgeon remain relatively small compared to those performing hips and knees, although each surgeon still tends to perform a greater volume of procedures than surgeons performing ankle and elbow replacements.

A total of 91% of the shoulder replacements were performed for elective indications and 9% for acute trauma.

The changing spectrum of use of differing types of shoulder implant is a notable feature and clarification is still needed about many aspects of these changes. One of the underlying problems which were originally being addressed by reverse polarity shoulder designs was significant rotator cuff deficiency. The dramatic increase in the use of reverse polarity shoulders in recent years suggests that these devices are not now being used solely in patients with deficient rotator cuffs. 

Revision rates are now available for the different types of shoulder implant and these demonstrate lower revision rates for total shoulders (stemmed, stemless and resurfacing) and for stemmed reverse polarity shoulders.  The revision rates are higher for hemiarthroplasty (stemmed, stemless and resurfacing) and for stemless reverse polarity shoulders.  There is evidence that fewer hemiarthroplasties are now being performed and this should be regarded as encouraging given the revision data.

As with unicompartmental knees, it is reasonable to think that the higher revision rate for some procedures such as hemiarthroplasty may be due to a number of complicated factors. There may be a perception that these operations would be simpler than more major revisions and there may be more willingness to undertake them. Similarly, revision is only one of the important endpoints and the issue of the actual symptomatic benefit is important. This aspect of outcomes may be more accurately reflected by the PROMs score and PROMs gain than by simple revision data.

Shoulder PROMs have therefore been introduced as an integral part of the NJR assessment of shoulders in particular as these have not previously been part of the National PROMs program. It is hoped that as this PROMs data increases in both breadth and duration it will help to demonstrate whether some of those implants which are “surviving” better may be doing so despite less good clinical outcomes or function, or whether these factors coincide to demonstrate the “best” procedures.

The PROMs data already demonstrate that considerable improvement is being achieved across the cohort of shoulder replacements, and it is anticipated that these data will be able to be stratified by implant and operation type in due course. This stratification will also be facilitated by the new implant database which is currently being introduced and which will allow for more granular comparisons when the numbers allow. The PROMs data do show that 12% of patients do not attain the minimum clinically significant improvement by six months post-operatively and all the major categories of shoulder replacement contain such patients. There are also seen to be 7% of elective patients who are worse after six months than pre-operatively, a matter that clearly needs investigation and explanation.

Young patients are seen to have high revision rates for shoulder replacement compared to those in similar aged hip and knee replacement patients. The revision rate is around 10% (10.2% males, 9.7% females) at four years in the under 55 year age group, compared to 4% at four years in TKR and 2.5% and 2% at four years for THR. This is important information in allowing properly informed consent for the patients, in particular for elective procedures.

These figures do nevertheless compare quite favourably to the 4-year revision rates for unicompartmental knees in the under 55 year age group (~7.5%).

 

Part Two - Clinial Activity

Part Two of the NJR’s 16th Annual Report can now to be found online via the registry’s dedicated NJR Reports website at: reports.njrcentre.org.uk .

Part Two presents data on clinical activity during the 2018 calendar year. This includes information on the volumes and surgical techniques in relation to procedures submitted to the NJR, with the most recent data being for the period 1 January 2018 to 31 December 2018. To be included in Part Two all procedures must have been entered into the NJR by 28 February 2019.

The double page infographic spread at the end of this report offers a visual summary of key facts relating to clinical activity during the 2018 calendar year. This can also be downloaded as a waiting room poster via reports.njrcentre.org.uk /downloads.

The information in Part Two now includes historical data, going back to 2005 in most cases. Using the dedicated website, readers are able to use interactive, filterable graphs to identify the key information and trends associated with the following reports for hip, knee, ankle, elbow and shoulder data (where sufficient data are available):

• Total number of hospitals and treatment centres in England, Wales and Northern Ireland able to participate in the NJR and the proportion actually participating

• Number of participating hospitals and the number and type of procedures performed

• Number of procedures undertaken as a proportion of all procedures submitted annually

• Procedure details by type of provider

• Primary procedure details by type of provider

• Types of primary replacements undertaken

• Patient characteristics for primary replacement procedures, according to procedure type

• Age and gender for primary replacement patients

• Patients’ physical status classification (ASA grades) for primary replacement procedures

• Body Mass Index (BMI) for primary replacement patients

• Indications for primary procedure based on age groups

• Age of patients undergoing primary joint replacement

• Surgical technique for primary replacement patients

• Thromboprophylaxis regime for primary replacement patients, prescribed at time of operation

• Reported untoward intra-operative events for primary replacement patients, according to procedure type

• Patient characteristics for revision procedures, according to procedure type

• Indication for surgery for revision procedures

• Trends in use of the most commonly used brands

For hips specifically

• Components removed during hip revision procedures

• Components used during single-stage hip revision procedures

• Trends in femoral head size and hip articulation

For knees specifically

• Implant constraint for primary procedures

• Bearing type for primary procedures

1.1 Annual Report introduction

The 16th Annual Report of the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) is the formal public report for the period 1 April 2018 to 31 March 2019. The report consists of a number of parts which are outlined in the summary table.

As part of the continued approach to sharing information about NJR progress, clinical activity and hospital and implant activity, the NJR has updated the data on its dedicated annual report website, ‘NJR Reports’, to showcase annual report data and information.

Some of these data can also be found in this printed report – in particular, the summaries and the full detailed, statistical analysis of outcomes following joint replacement surgery.

A short summary of the NJR’s progress over 2018/19 is included below and in both the Chairman’s Foreword and Annual Report Executive Summary.

Additional information and reports are available online via ‘NJR Reports’.

1.2 Annual progress

As at 31 March 2019, the total number of procedures submitted to the NJR was approximately 2.8 million. In the financial year 2018/19, a total of 259,859 records were submitted, which is an increase of 7,608 over the previous year.  This increase in submissions may correlate with the NJR’s data quality audit and the subsequent creation of new records and re-submission of corrected records.

Overall key performance indicators demonstrated:

• Informed patient consent (to allow or reject the recording of their personal details in the NJR) was recorded as 93.8%, a slight decrease from informed consent in the previous year (2017/18 94.4%). England, Wales and the Isle of Man maintained the same consent rates as last financial year (92.3%) and Northern Ireland had a slight drop from 96.1% to 95.7%.

• Linkability (the ability to link a patient’s primary procedure to a revision procedure) was recorded as 95.9%, an increase of 1.9% on the previous year.

Whilst a comparison of successive years will show variation in the rates of the key indicators of consent and linkability, these may be attributable to the outcomes of the data quality audits that have taken place in recent years. This has resulted in the retrospective submission of missing procedures for which some will not have had patient consent recorded. Linkability is dependent on the submission or tracing (via PDS) of NHS and, in Northern Ireland, HCN numbers. Please see the data completeness and quality indicators section on reports.njrcentre.org.uk for further detail.

Data quality was still the primary focus in 2018/19 as we continued our data quality audit across NHS and independent sector units. The NJR data quality audits began in 2015 and were slow to be embraced by units, but there has been a steady improvement in response and in the audit covering the 2017/18 financial year, 42% of units had completed their audits within six months. The completion report provided to each Trust or independent organisation provides valuable feedback on compliance and recommends improvements in local processes.

This year saw the development of an automated data quality audit process to further improve the submission of data. Units will be able to upload a local Patient Administration System data file directly to the NJR and view the audit results. This reduces the burden on hospital staff and gives units greater control of their data. The pilot of this system launched in April 2019.

Surgeons already have access to the NJR's Clinician Feedback system, allowing them to review and validate their data. This has been further enhanced in 2019 with the introduction of an email notification when procedures are revised or a patient death is recorded. This allows surgeons to check their data on a more regular and timely basis as well as compare performance with their peers on a local and national level.

Consultant Level Reports can be downloaded in pdf format in Clinician Feedback. Surgeons can record the download within the website and that this has been reviewed and will be used as part of their annual appraisal and revalidation cycle. This also supports the GMC's commitment to members’ participation in quality improvement activities.

Further progress and updates will be available at reports.njrcentre.org.uk and also via the main NJR website at www.njrcentre.org.uk.

1.3 Patient Decision Support Tool 

We were delighted to launch the NJR Patient Decision Support Tool (PDST) in 2019, available at www.njrcentre.org.uk/njrcentre/Patients/Patient-Decision-Support-Tool. Developed by the University of Sheffield and the University of Bristol with funding from Arthritis Research UK grant 20894, this is a web-enabled personalised tool for patients considering hip or knee replacement and has been a core development strategy for the NJR to increase the public use of the dataset.

This simple tool enables patients to enter their personal demographic information and the type of operation they are considering, in order to understand their personalised risks and benefits of proceeding with surgery.

The clinician-assisted version of the tool allows the additional input of surgical variables into the algorithm. The algorithm then uses the linked data from the NJR and national PROMs data to calculate the most likely PROMs score at six months post-operatively, a 1-year mortality profile and an eight to ten year revision risk estimate. The algorithms behind the tool have been validated internally and also externally in collaboration with the Norwegian Arthroplasty Register.

Decision aids fill the gap between population level data and its application to a patient’s individual circumstances. This better informs patients making choices about healthcare interventions, enhances patient participation in the process, reduces decisional conflict and subsequently benefits healthcare economies through improved clinical outcomes and better resource utilisation.

The NJR Patient Decision Support Tool helps patients considering joint replacement make evidence-based choices about their treatment and share decision-making with their clinicians when considering the benefits and risks of undergoing joint replacement. The tool underscores the NJR’s recognition that patients wish to receive information that is tailored to their own circumstances and is consistent with the recent Montgomery ruling¹ on the personalisation of informed consent. This project represents a substantial initiative on the part of the NJR to meet one of our core objectives to improve accessibility of the NJR resources to patients and promote shared, informed and value-based decision-making.

Having now launched this tool, we are continuing our work to further develop it.  Further algorithms are being developed by the Universities of Sheffield and Bristol that will enable the most up-to-date NJR data to be used to calculate projected risks and benefits of joint replacement surgery. We are also working towards updates of the algorithm and website that will enable an automatic refresh of the system as new outcomes data comes online.

1.4 Data Access Portal and research applications  

Another key aim this year has been the creation and development of a secure means of sharing NJR data with researchers.

The NJR Research committee is responsible for delivering the NJR research agenda and its objective is to enhance the understanding of the science of arthroplasty, improve clinical practice and benefit public health. The committee aims to maximise the value of the NJR to research by making NJR data widely available through an impartial and objective application process.

The NJR is working to make the process of applying for and working on NJR data more straightforward for researchers through our new Data Access Portal. The aims of the portal are to provide secure access by approved researchers to specified sub-sets of the NJR dataset. This new approach will enable the NJR to maximise safe access to the data whilst meeting our information governance legal obligations. It will also allow the NJR to reduce the analysis burden on researchers by providing a single data source. Finally, it will enable the NJR to service a larger number of research requests whilst giving greater protection to the data.

The Data Access Portal will also incorporate pre-specified linkage with other national datasets, including Hospital Episode Statistics, mortality data and National Patient Reported Outcomes through a sub-licensing agreement with NHS Digital. This pre-linkage of the datasets will allow the NJR to act as the single source of access to further reduce the burden of the application process for external researchers.

With the redesign of the NJR website, we will be introducing a fully online process for managing research data access requests, with end-to-end management of the application process from initial expression of interest through to final project report download. Several licensed end-user analysis tools will be available to support interaction with the data, including STATA and Microsoft Office, as well as open source tools Python and R. All of the data extraction and analysis will take place within this secure research environment without data ever leaving the NJR servers. Users will be able to save files/outputs from their analysis to a secure area within the Data Access Portal for subsequent download.

Underpinning the Data Access Portal is a “research-ready” dataset. Taken together, these initiatives will improve the utility of the NJR dataset for external researchers, whilst protecting the confidentiality of identifiable data.

¹ Montgomery v Lanarkshire Health Board [2015] SC 11 [2015] 1 AC 1430

Executive summary

Professor Mike Reed - Chairman, Editorial Board 

This year our annual report is based on 2,835,101 records and we maintain our position as the largest registry in the world. We are presenting joint replacement up to 15 years of follow-up, with data on hips, knees, shoulders, elbows and ankle replacements. A further quarter of a million records were added this year.

Progress and achievements

In order to provide high-quality registry data and feedback to the orthopaedic community, patients and other stakeholders, the NJR has made great progress in improving data quality. The data quality process works by matching information held in the NJR with information held on hospital systems in order to accurately capture every relevant procedure, and make sure it is recorded and used for analysis. This process has been running successfully since 2015 in the NHS and from 2016 in the private sector, and this has been a key component in our strategy in recent years. This year saw the launch of the pilot of an automated data quality system which will directly compare a hospital’s reported activity and NJR activity, and produce queries so that any discrepancies can be reviewed. This automation will allow the NJR to perform the audit in a more efficient and streamlined way, and will reduce some of the burden placed upon both Trust and NJR staff in manually checking data. Automation also includes an early alarm for low/non-compliance, enabling timely action to address this. Looking forward, we will extend the quality audit into shoulders, elbows and ankles, and work to bring these joints on board has already commenced.

With improvements in registry-wide data quality we can now offer better information to patients considering surgery about their own particular risks and benefits. For hip and knee replacements, a Patient Decision Support Tool has been developed using NJR data, for use by patients and also clinical staff so that they can input details of their own personal circumstances to estimate their individual patient outcome, benefits of surgery and risks regarding mortality and revision surgery, based on a number of relevant metrics. This is an exciting development and I recommend that you go online and see how the tool works. It is likely that as traction gains, patients will be interacting with this and no doubt will come to consultations better equipped to share in their treatment plans with this information. The Patient Decision Support Tool can be found at www.njrcentre.org.uk/njrcentre/Patients/Patient-Decision-Support-Tool

For the first time, this year surgeon and hospital performance data will be produced over a rolling 10-year period, rather than the whole life of the registry. Thus, historical data will now no longer be used and a more up-to-date assessment of contemporary practice will be presented in surgeon and hospital level data.

In order to allow wider participation in research using NJR data, a research Data Access Portal has been developed. More detailed information on this is provided in Part 1 of this report.

It has been a busy year for research outputs with this year’s NJR Research Fellows producing high quality and prize winning work in journals such as The Lancet. NJR data have been used across a wide range of topics and some of these are detailed in Part 4 of this report. Many more of the publications can be found in Appendix 4 in the downloads section of reports.njrcentre.org.uk .

As always, the NJR and its committees have been visible at both national and international meetings with a presence at the specialist society conferences including BOA Congress, EFORT, BESS, BHS, BASK EHS, EORS and ISAR and other societies’ events being planned for later this year.

Main headlines from the data

For hip replacement we now have well over one million procedures, some with over 15 years of follow-up. Hip surgeons are performing an average of 60 joint replacements per year. This year’s report confirms the increasing trend for hybrid hip replacement over the last five years. Three and five year revision rates have reduced over the last ten years, after the peak of metal-on-metal, and the introduction of NJR clinician feedback since 2008. The data is structured to show the effect of patient and implant factors on revision estimates. For example, patient factors include gender and age at time of surgery, while implant factors include type of fixation, brand, bearing and head size. Ceramic-on-polyethylene looks encouraging with longer follow-up, and as a bearing choice this is increasing. Young women form the group that are most likely to be revised. Reassuringly the numbers of revisions performed each year has decreased since 2012 despite higher numbers of primaries. For those joints that are revised, the longer the primary lasts, the lower the chance of re-revision.

There are over one million knee replacement procedures contributing to the registry and we add to it with over 100,000 new cases per year. Surgeons are performing around 40 cases per year on average. Although the patient groups are not necessarily comparable, the results show the lowest revision rates for cemented unconstrained fixed bearing TKR and cemented TKR with monobloc polyethylene tibias. The revision rates in cemented TKRs that are posterior-stabilised and those that have mobile bearings remain higher. The revision rates for UKRs remain substantially higher than for TKR, this is most marked in the patellofemoral replacement group.

This year’s report showcases an increasing dataset in both the shoulder and elbow registries with both revision and perioperative mortality being included. Data shows that reverse polarity shoulder replacement has increased further and now dominates practice at 57% while proximal humeral hemiarthroplasty continues to diminish. Usefully, PROMs data is provided and can be interpreted alongside revision rates. More elective humeral hemiarthoplasties are being revised earlier and while it can be argued this revision is an easier operation to perform, the PROMs data in this report does suggest lower change scores are being achieved in the specific patient groups that receive a hemiarthoplasty.

We now have over 5,000 ankle operations recorded on the registry, the majority of which are uncemented implants. There is a cumulative percentage of revision at seven years following a primary ankle replacement of 8.51%, but there is a belief that not all revisions are being entered, and both the British Orthopaedic Foot and Ankle Society (BOFAS) and the NJR encourage surgeons to complete forms for all revisions, conversion of an ankle replacement to an arthrodesis, and amputations, which are mandatory requirements.

Concluding acknowledgements

There is considerable additional information available online and I would encourage you to explore the NJR’s dedicated annual report website at reports.njrcentre.org.uk. The website offers a helpful interactive platform for Part Two of the report, which is the descriptive NJR data; supporting appendices; and, when published, the latest NJR Patient and Public Guides to the annual report.

The NJR continues to work with many stakeholders; the most important, of course, are the patients, who I would like thank for allowing the NJR to use their data.

The NJR is a huge team effort. Many thanks also to the following without which the NJR could not function:

All members of the NJR Steering Committee

Members of the NJR sub-committees:
Executive
Data Quality
Editorial Board
Implant Scrutiny
Medical Advisory
Regional Clinical Coordinators
Research
Surgical Performance

Members of Data Access Review Group

Members of the NJR Patient Network

Other organisations:
Medicines and Healthcare products Regulatory Agency (MHRA)
Care Quality Commission (CQC)
NHS England
NHS Digital
NHS Improvement
British Orthopaedic Association (BOA)
British Hip Society (BHS)
British Association for Surgery of the Knee (BASK)
British Elbow and Shoulder Society (BESS)
British Orthopaedic Foot and Ankle Society (BOFAS)
European Orthopaedic Research Society (EORS)
Healthcare Quality Improvement Partnership (HQIP)
Northgate Public Services (UK) Ltd
University of Bristol
University of Oxford
Confidentiality Advisory Group
Association of British HealthTech Industries (ABHI)

On a personal note I would particularly like to thank Laurel Powers-Freeling, Chairman of the NJR and Elaine Young, NJR Director of Operations.

Northgate Public Services, University of Bristol and University of Oxford teams have done a first class job, as always. 

Particular personal thanks to Vicky McCormack and Deirdra Taylor for getting the final report into shape.

Martyn Porter stepped down this year having served for over 15 years on the steering committee and led a huge variety of projects to support the NJR. We are hugely indebted to him, and he is greatly missed across the breadth of the NJR’s activities.

Professor Mike Reed

Chairman of the NJR Editorial Board