Trust, Local Health Board and unit-level activity and outcomes

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.

Following discussions with the British Association for Surgery of the Knee (BASK) and British Orthopaedic Association (BOA), our alarm process has been amended to identify surgeons who appear as potential outliers for their total knee replacement (TKR) practice data and/or their unicondylar knee (UKR) practice and/or their patellofemoral joint replacement (PFJ) data alone rather than just based on their overall knee practice. Units are now notified for these sub-strata, but also for their overall knee replacement outcomes.

Ten hospitals had higher than expected rates of revision for hip replacement over the past five years, while 24 hospitals had higher than expected rates over the past ten years.

Over the five-year period, eight hospitals were identified with higher than expected overall knee revision rates, while eight were identified for total knee replacement, three for unicondylar knee replacement and none for patellofemoral knee replacement. Over the past ten years, higher than expected overall knee revision rates were seen for 25 hospitals, while 24 hospitals had higher rates for total knee replacement, eight for unicondylar knee replacement and two for patellofemoral knee replacement.

The 90-day mortality rate 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 hemiarthroplasty 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 here have been notified. All units are provided with an NJR Annual Clinical Report and additionally have access to the online NJR Management Feedback service.

Important note about the outlier hospitals listed
In earlier annual reports, we reported outlying hospitals based on all cases submitted to the registry since 1 April 2003. To reflect changes in hospital practices and component use, we now report outlying hospitals based on the last five years (17 February 2018 to 17 February 2023) and ten years of data (17 February 2013 to 17 February 2023 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.

Table 4.5 Outliers for hip mortality rates since 2018¹.
None identified

Table 4.6 Outliers for knee mortality rates since 2018¹.
None identified

Table 4.7 Outliers for hip revision rates, all linked primaries from 2018¹.
Broadgreen Hospital, Liverpool
Hexham General Hospital
King Edward VII's Hospital Sister Agnes, London
Milton Keynes Hospital
Mount Vernon Treatment Centre, Middlesex
North Manchester General Hospital
North Tyneside General Hospital, Oxford
Nuffield Orthopaedic Centre
Spire Liverpool Hospital
Wansbeck Hospital

Table 4.8 Outliers for hip revision rates, all linked primaries from 2013².
Basingstoke and North Hampshire Hospital
Bassetlaw Hospital, Northamptonshire
Broadgreen Hospital, Liverpool
Dewsbury and District Hospital
Fitzwilliam Hospital, Peterborough
Hull Royal Infirmary
John Radcliffe Hospital, Oxford
King Edward VII's Hospital Sister Agnes, London
London Bridge Hospital
Meriden Hospital, Coventry
Milton Keynes Hospital
North Tyneside General Hospital
Nuffield Orthopaedic Centre, Oxford
Orthopaedics and Spine Specialist Hospital, Peterborough
Peterborough City Hospital
Salisbury District Hospital
Southampton General Hospital
Spire Hartswood Hospital, Brentwood
Spire Methley Park Hospital, Leeds
St Richard's Hospital, Chichester
The Tunbridge Wells Hospital
University Hospital Aintree
Wansbeck Hospital
Weston General Hospital

Table 4.9 Outliers for overall knee revision rates, all linked primaries from 2018¹.
Bath Clinic
Guy's Hospital, London
Hospital of St John and St Elizabeth, London
King Edward VII's Hospital Sister Agnes, London
Milton Keynes Hospital
Mount Vernon Treatment Centre, Middlesex
Nuffield Orthopaedic Centre, Oxford
Spire Southampton Hospital

Table 4.10 Outliers for overall knee revision rates, all linked primaries from 2013².
Ashford Hospital
Bishops Wood Hospital, Middlesex
Ealing Hospital
Guy's Hospital, London
Heatherwood Hospital, Ascot
Hillingdon Hospital, Uxbridge
Hospital of St John and St Elizabeth, London
King Edward VII's Hospital Sister Agnes, London
London Independent Hospital
Meriden Hospital, Coventry
Mount Vernon Treatment Centre, Middlesex
Nottingham City Hospital
Nuffield Health Haywards Heath Hospital
Nuffield Orthopaedic Centre, Oxford
Orthopaedics and Spine Specialist Hospital, Peterborough
Scarborough General Hospital
Southmead Hospital, Bristol
Spire Hull and East Riding Hospital
Spire Southampton Hospital
Springfield Hospital, Chelmsford
St Mary's Hospital, Isle of Wight
St Richard's Hospital, Chichester
Sussex Orthopaedic Centre, Haywards Heath
The London Clinic
The Royal National Orthopaedic Hospital (Stanmore), London

Table 4.11 Outliers for total knee replacement revision rates, all linked primaries from 2018¹.
Bath Clinic
Guy's Hospital, London
Hospital of St John and St Elizabeth, London
Mount Vernon Treatment Centre, Middlesex
Nuffield Orthopaedic Centre, Oxford
Southmead Hospital, Bristol
Spire Southampton Hospital
Torbay Hospital

Table 4.12 Outliers for total knee replacement revision rates, all linked primaries from 2013².
Bath Clinic
Ealing Hospital
Guy's Hospital, London
Heatherwood Hospital, Ascot
Hillingdon Hospital, Uxbridge
Hospital of St John and St Elizabeth, London
London Independent Hospital
Mount Vernon Treatment Centre, Middlesex
Nevill Hall Hospital, Abergavenny
Nottingham City Hospital
Nuffield Health Haywards Heath Hospital
Nuffield Orthopaedic Centre, Oxford
Ormskirk and District General Hospital
Orthopaedics and Spine Specialist Hospital, Peterborough
Southampton General Hospital
Southmead Hospital, Bristol
Spire Hull and East Riding Hospital
Spire Southampton Hospital
St Mary's Hospital, Isle of Wight
St Richard's Hospital, Chichester
Sussex Orthopaedic Centre, Haywards Heath
The Royal National Orthopaedic Hospital (Stanmore), London
Torbay Hospital
University Hospital Llandough

Table 4.13 Outliers for unicondylar knee replacement revision rates, all linked primaries from 2018¹.
King Edward VII's Hospital Sister Agnes, London
Springfield Hospital, Chelmsford
St Michael's Hospital, Enfield

Table 4.14 Outliers for unicondylar knee replacement revision rates, all linked primaries from 2013².
Ashford Hospital
Barnsley District General Hospital
Bishops Wood Hospital, Middlesex
King Edward VII's Hospital Sister Agnes, London
Meriden Hospital, Coventry
Springfield Hospital, Chelmsford
Sunderland Royal Hospital
The Cherwell Hospital, Banbury

Table 4.15 Outliers for patellofemoral knee replacement revision rates, all linked primaries from 2018¹.
None identified

Table 4.16 Outliers for patellofemoral knee replacement revision rates, all linked primaries from 2013².
Meriden Hospital, Middlesex
Nuffield Health Tees Hospital

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 across all of the NJR data quality audits. Units with lower data quality compliance are automatically excluded from these lists, but can revisit their automated audits to improve their compliance results.

Table 4.17 Better than expected hip revision rates, all linked primaries from 2018¹.
None identified

Table 4.18 Better than expected hip revision rates, all linked primaries from 2013².
Bedford Hospital South Wing
Calderdale Royal Hospital, Halifax
Craigavon Area Hospital
Goring Hall Hospital, Worthing
Ipswich Hospital
Musgrave Park Hospital, Belfast
Practice Plus Group Hospital - Emersons Green, Bristol
Sunderland Royal Hospital
The Horder Centre, Crowborough
Ulster Independent Clinic, Belfast

Table 4.19 Better than expected overall knee revision rates, all linked primaries from 2018¹.
None identified

Table 4.20 Better than expected overall knee revision rates, all linked primaries from 2013².
Craigavon Area Hospital
Hexham General Hospital
Ipswich Hospital
Musgrave Park Hospital, Belfast
Norfolk and Norwich Hospital
North Tyneside General Hospital
Nottingham Woodthorpe Hospital
Nuffield Health Cambridge Hospital
Nuffield Health Wolverhampton Hospital
Practice Plus Group Hospital - Emersons Green, Bristol
Spire Norwich Hospital
Stepping Hill Hospital, Stockport
The Elective Orthopaedic Centre, London
The Horder Centre, Crowborough

Table 4.21 Better than expected total knee replacement revision rates, all linked primaries from 2018¹.
None identified

Table 4.22 Better than expected total knee replacement revision rates, all linked primaries from 2013².
Alexandra Hospital, Redditch
Hexham General Hospital
Ipswich Hospital
Musgrave Park Hospital, Belfast
Norfolk and Norwich Hospital
North Tyneside General Hospital
Nottingham Woodthorpe Hospital
Nuffield Health Cambridge Hospital
Nuffield Health Wolverhampton Hospital
Spire Norwich Hospital
The Elective Orthopaedic Centre, London
The Horder Centre, Crowborough
Whiston Hospital, Prescot

Table 4.23 Better than expected unicondylar knee replacement revision rates, all linked primaries from 2018¹.
None identified

Table 4.24 Better than expected unicondylar knee replacement revision rates, all linked primaries from 2013².
Nuffield Health Derby Hospital
Nuffield Orthopaedic Centre, Oxford
Practice Plus Group Hospital - Emersons Green, Bristol
Royal Derby Hospital

Table 4.25 Better than expected patellofemoral knee replacement revision rates, all linked primaries from 2018¹.
None identified

Table 4.26 Better than expected patellofemoral knee replacement revision rates, all linked primaries from 2013².
None identified

¹Date range 17 February 2018 to 17 February 2023 inclusive.
²Date range 17 February 2013 to 17 February 2023 inclusive.

Overall in 2022, 138 NHS trusts and local health boards (comprising 254 separate hospitals) and 179 independent hospitals were open and eligible to report patient procedures to the registry. Data were not submitted in 2022 by six NHS hospitals and four independent hospitals.

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

NHS hospitals
44% of NHS hospitals achieved a consent rate greater than 95%
29% achieved a consent rate of 80% to 95%
27% recorded a consent rate of less than 80%

Independent hospitals
67% of independent hospitals achieved a consent rate greater than 95%
23% achieved a consent rate of 80% to 95%
10% recorded a consent rate of less than 80%

There has been an increase in recorded consent for all submitting units when compared to the previous year, with those achieving a higher than 95% rate rising to 54%, from 47% in 2021 (43% in 2020). Consent rates are returning to pre-pandemic levels; this can be related to the ratio of elective to trauma cases, which changed significantly during 2020, having a higher proportion of trauma cases compared to previous years. There was a significant reduction in elective cases due to COVID and trauma cases have a higher rate where NJR consent is not obtained. Similarly, the proportion of entries in which there are significant data to enable the patient to be linked to an NHS number (linkability) is listed.

NHS hospitals
77% achieved a proportion of patients with a linkable NHS number greater than 95%
18% achieved a proportion of 80% to 95%
5% recorded a proportion of less than 80%

Independent hospitals
77.7% achieved a proportion of patients with a linkable NHS number greater than 95%
17.7% achieved a proportion of 80% to 95%
4.6% recorded a proportion of less than 80%

In 2022, 77% of all submitting units achieved over 95% linkability, a slight increase on the rate seen in 2021.

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.

Performance and data entry quality indicators are shown here for trusts and local health boards (many of whom comprise more than one hospital) and independent (private) providers in England, Wales, Northern Ireland, the Isle of Man and Guernsey for the 2022 calendar year. Outcomes analysis after hip and knee replacement surgery is also provided for the period 2013 to 2023.

The full analysis for units can be found in the document available in the downloads section.