How to Read Your Surgeon’s NJR Profile

Part of The Joint Replacement Guide — Phase 6: The Bigger Picture · Article 38 of 44 · Hip & Knee

Key Points

The National Joint Registry publishes useful information about the recent joint-replacement practice of consultant surgeons and hospitals.
The operation numbers are attributed to the Consultant in Charge, who may not necessarily have personally performed every operation listed.
A surgeon’s “revision” number shows how many revision operations were recorded under that consultant—not how many of their own primary replacements failed.
The NJR does not currently publish individual surgeons’ revision rates publicly.
Surgeon-level PROMs are not normally shown; patient-reported improvement may be available on the hospital profile.
NJR information is best used to support questions and shared decision-making, not to create a simplistic league table.

You can view my published NJR information through the Surgical Outcomes page of this website.

What Is the NJR?

The National Joint Registry records information about hip, knee, ankle, elbow and shoulder replacement procedures submitted by participating NHS and independent hospitals in England, Wales, Northern Ireland, the Isle of Man and Guernsey.

It began collecting hip and knee information in England and Wales in 2003 and now contains more than four million procedure records, making it the largest orthopaedic registry of its kind.[1]

The registry is used to monitor:

joint-replacement implants
hospitals and surgical units
surgical practice and outcomes
patterns of revision surgery
possible patient-safety concerns.

The public NJR Surgeon and Hospital Profile allows patients to search by surgeon name, GMC number or hospital.[2]

First, Check the Surgeon and Reporting Period

Make sure that you have found the correct surgeon. The profile normally shows the surgeon’s:

name and GMC number
declared specialist areas
relevant professional memberships, where supplied
hospitals in which NJR activity has been recorded
one-year and three-year practice profiles.

The profile is refreshed annually, so it is a snapshot of defined reporting periods rather than a live total of everything the surgeon has ever performed.[2]

A surgeon’s own website may contain more recent figures, but these should clearly identify their source and reporting period.

“Consultant in Charge” Does Not Always Mean “Operating Surgeon”

This is one of the most important qualifications on the page.

Public NJR operation numbers are attributed to the Consultant in Charge of the patient. That consultant has overall responsibility for the episode of care but may not necessarily have performed every operation personally. Some procedures may have been undertaken wholly or partly by another appropriately supervised surgeon.

This is particularly relevant in teaching hospitals, where registrars, fellows and other consultants may operate as part of a team.

The figures are therefore best understood as procedures undertaken or overseen under that consultant’s care, not necessarily an exact personal operating log.[2]

If this distinction matters to you, it is reasonable to ask who is expected to perform your operation and what level of supervision will apply.

Understanding the Practice Profile

The one-year and three-year practice profiles show the number and type of procedures recorded under the consultant. Depending on the surgeon’s practice, this may include:

primary hip replacement
total knee replacement
partial or unicompartmental knee replacement
patellofemoral replacement
hip or knee revision surgery
other joint replacements.

The page also provides a national average for comparison. This describes activity, not quality.

A surgeon whose work is highly specialised may have a very different case mix from the national average. For example, a revision specialist may perform fewer straightforward primary replacements but substantially more complex revisions.

A Crucial Distinction: Revision Volume Is Not Revision Rate

If the profile says that a surgeon performed or oversaw 20 hip revisions, this means that 20 revision operations were recorded under that consultant during the reporting period.

It does not mean that 20 of the surgeon’s own primary hip replacements failed.

Revision surgeons commonly treat patients whose original operations were performed elsewhere. A high revision volume may therefore indicate a specialist referral practice rather than a high failure rate.

The NJR monitors individual surgeon revision outcomes internally as part of its accountability and outlier process, but it does not publish individual surgeons’ revision rates on the public Surgeon and Hospital Profile website.[3]

Risk-adjusted revision information may instead be displayed at hospital or unit level. Even there, the figures need interpretation because specialist referral centres may receive unusually complex cases.

What Does Case Volume Tell You?

Research suggests a general association between higher surgeon volume and some improved outcomes after primary hip and knee replacement, although the relationship is not identical for every complication or procedure.[4,5]

Regular experience with a particular operation is relevant, especially for technically demanding or less commonly performed procedures. However, a volume figure alone does not tell you:

whether every case was performed personally
how complex the cases were
the surgeon’s technical quality
the quality of the wider hospital team
whether the surgeon is the right match for your particular problem
what your own result is likely to be.

There is no single number on the public NJR profile that defines a “good surgeon.” Volume is better used as a starting point for a question such as:

“How frequently do you personally perform the operation you are recommending for me?”

For a partial knee replacement, complex primary replacement or revision procedure, it may also be useful to ask specifically about experience with that procedure rather than total joint-replacement volume.

Patient Characteristics and Case Mix

For hip and knee practice, the profile may show characteristics of the patients whose procedures were recorded under the consultant, such as:

age
sex
body mass index
ASA grade, which gives an indication of general medical health
whether the diagnosis was osteoarthritis or another condition.

This provides context about the type of patients treated. It is not an assessment of whether those patients should or should not have undergone surgery.

Case mix matters because surgeons and centres treating older, medically complex or unusual patients may reasonably have different outcome patterns from those treating a more selected population.

Understanding 90-Day Mortality

For primary hip and knee replacement, the public surgeon profile may display risk-adjusted mortality within 90 days of surgery.

The graph uses a standardised mortality ratio, not a simple percentage. It compares observed mortality with the number statistically expected after accounting for aspects of the patients’ risk profile.[2]

The result is generally shown using a funnel plot:

the surgeon is represented by a marker
the central line represents the national average
control limits show the range within which variation may reasonably occur
a result within the control limits is considered within the expected statistical range.

A marker being above or below the central average does not necessarily mean that one surgeon is better or worse. Death after surgery is rare, and small numbers or random events can cause considerable apparent variation. Risk adjustment also cannot account perfectly for every difference between patients.

A result outside a control limit is a signal requiring investigation; it is not, by itself, proof of negligence or poor care.

Where Are the Revision Rates and PROMs?

This is an area in which the surgeon and hospital pages differ.

Surgeon profile

The current public surgeon profile principally provides:

recent procedure volumes
types of procedure
hospitals where activity was recorded
aspects of patient case mix
risk-adjusted 90-day mortality for eligible hip and knee procedures.

It does not publicly show the individual surgeon’s revision rate.[3]

Hospital profile

The hospital profile may additionally show:

risk-adjusted revision outcomes
risk-adjusted 90-day mortality
data quality and submission information
Patient-Reported Outcome Measures, where available.

Hospital PROMs may include improvement in the Oxford Hip Score, Oxford Knee Score, EQ-5D or EQ-VAS. These relate to the hospital or trust and should not be presented as a particular surgeon’s individual PROM result.

PROMs data may be unavailable where insufficient eligible responses have been collected or linked.

What If a Profile Is Missing or Numbers Look Incomplete?

A missing or incomplete profile does not automatically mean that a surgeon is inexperienced or has poor results.

Possible explanations include:

no eligible activity during the most recent publication period
procedures recorded under another Consultant in Charge
incomplete or incorrectly attributed submissions
data-quality concerns leading to suppression
work performed outside the geographical or procedural scope of the NJR
small numbers being suppressed to protect confidentiality.

The NJR states that figures below a specified threshold may be displayed as “fewer than five.”[2] Consequently, visible totals may not add up exactly.

A surgeon can explain how the NJR profile relates to their actual practice and whether they maintain an independently validated personal logbook.

Questions Worth Asking

The NJR profile can help you ask more precise questions, including:

How many of these operations do you personally perform each year?
Does the figure include operations performed by trainees or other surgeons under your care?
How much of your practice involves primary versus revision surgery?
Do you regularly perform the specific procedure recommended for me?
Are my circumstances more complex than those of the average patient?
How should I interpret your mortality graph?
Where can I find outcome information for the hospital and the wider surgical team?
Do you audit complications, revisions and patient-reported outcomes in your own practice?

A willingness to explain data clearly is generally more informative than an isolated number presented without context.

In More Depth

NJR data is observational registry data. Its great strengths are its scale, national coverage and ability to link primary procedures with later revisions. Its limitations include dependence on correct submission, consent, patient identifiers and accurate attribution.

The registry reported an overall procedure-submission compliance rate of approximately 97.7% for participating hospitals in its latest available audit period, but completeness and linkability still vary.[6]

Risk adjustment improves comparisons but cannot remove every difference in case complexity, referral patterns or random variation. Public profiles should therefore be treated as transparent sources of information—not exact rankings of surgeons from best to worst.

The safest interpretation combines:

the surgeon’s NJR practice profile
the hospital’s outcome and data-quality information
the surgeon’s experience with your particular procedure
the quality of the wider multidisciplinary team
your consultation and individual treatment needs.

This article provides general information about interpreting publicly available registry data. NJR profiles and reporting methods are updated periodically, so consult the explanations displayed on the current NJR website alongside each figure.

References

National Joint Registry. Introduction to the NJR Annual Report 2025. Available at: https://reports.njrcentre.org.uk/AR-Introduction
National Joint Registry. NJR Surgeon and Hospital Outcomes Website—information for patients. Available at: https://www.njrcentre.org.uk/patients/njr-surgeon-and-hospital-outcomes-website/
National Joint Registry. Accountability and Transparency Model: frequently asked questions. Available at: https://www.njrcentre.org.uk/about-the-njr/accountability-and-transparency-faqs/
Malik AT, Jain N, Scharschmidt TJ, Li M, Glassman AH, Khan SN. Does surgeon volume affect outcomes following primary total hip arthroplasty? A systematic review. Journal of Arthroplasty. 2018;33(10):3329–3342. doi: 10.1016/j.arth.2018.05.040
Lau RL, Perruccio AV, Gandhi R, Mahomed NN. The role of surgeon volume on patient outcome in total knee arthroplasty: a systematic review of the literature. BMC Musculoskeletal Disorders. 2012;13:250. doi: 10.1186/1471-2474-13-250
National Joint Registry. Data completeness and quality. Available at: https://reports.njrcentre.org.uk/Data-Completeness-and-quality

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