Rutherford Category Interpreter
Rutherford Category Interpreter
Seven categories of chronic limb ischaemia with the objective pressure criteria the 1997 reporting standard attaches to each — and the separate acute classification whose categories are also numbered IIa and IIb.
Rutherford category, chronic limb ischaemia
Clinical plus post-exercise and resting pressuresIntermittent claudication, treadmill completed, post-exercise ankle pressure 62 mmHg, resting ankle pressure 88 mmHg
The seven chronic categories and their objective criteria
| Grade | Category | Clinical | Objective criterion |
|---|---|---|---|
| 0 | 0 | Asymptomatic, no haemodynamically significant disease | Normal treadmill test and normal reactive hyperaemia testing |
| I | 1 | Mild claudication, walking capacity preserved | Completes treadmill; post-exercise ankle pressure over 50 mmHg but at least 20 mmHg below resting |
| I | 2 | Moderate claudication, increased walking limitation | Between categories 1 and 3 — no numeric criterion is published |
| I | 3 | Severe claudication, marked walking impairment | Cannot complete treadmill; post-exercise ankle pressure under 50 mmHg |
| II | 4 | Ischaemic rest pain, often worse at night | Resting ankle pressure under 40 mmHg; toe pressure under 30 mmHg; flat or barely pulsatile pulse volume recordings |
| III | 5 | Minor tissue loss — non-healing ulcer, focal gangrene, diffuse pedal ischaemia | Resting ankle pressure under 60 mmHg; toe pressure under 40 mmHg; same pulse volume finding |
| III | 6 | Major tissue loss above the transmetatarsal level, foot not salvageable | Same haemodynamic criteria as category 5 |
The OTHER Rutherford classification — acute limb ischaemia
| Category | Description | Sensory loss | Motor deficit |
|---|---|---|---|
| I | Viable | None | None |
| IIa | Marginally threatened | None or minimal, toes only | None |
| IIb | Immediately threatened | More than toes | Mild to moderate |
| III | Irreversible | Profound, anaesthetic | Profound, paralysis |
The standard that attaches a pressure to a symptom
Rutherford’s classification, published as a Society for Vascular Surgery reporting standard in 1997, does what Fontaine’s does not: it attaches an objective haemodynamic criterion to each clinical category. Four grades, 0 to III, subdivide into seven categories, 0 to 6 — asymptomatic, three degrees of claudication, ischaemic rest pain, minor tissue loss and major tissue loss — and the point of the standard was that reports from different centres should mean the same thing.
The criteria for claudication are the ones worth knowing, because they are the reason a treadmill exists in a vascular laboratory. Category 1 requires that the patient completes the standard treadmill test with a post-exercise ankle pressure above 50 mmHg that is nonetheless at least 20 mmHg below the resting value. Category 3 requires that the patient cannot complete it and that the post-exercise pressure is below 50 mmHg. Category 2 has no criterion of its own and is defined as lying between the two, which is the published instrument rather than an omission here. The post-exercise pressure matters because a resting index can be normal or borderline in a limb that claudicates: exercise unmasks the lesion by dropping the distal pressure that collateral flow was maintaining at rest.
The criteria for the ischaemic categories lean on pressures that the same calcification which distorts a resting ankle-brachial index also distorts. Category 4 asks for a resting ankle pressure below 40 mmHg, categories 5 and 6 for below 60 mmHg, and the standard offers a toe pressure — below 30 mmHg and below 40 mmHg respectively — alongside, precisely because the ankle pressure cannot be trusted in a diabetic or renal limb. This page therefore reports the clinical category and whether the pressure criterion was met as two separate facts, because a foot with tissue loss and an ankle pressure of 90 mmHg is a real and common finding and resolving it by discarding one half would be dishonest.
Two warnings. The first is the one this page exists for: Rutherford also published a classification of ACUTE limb ischaemia, with categories I, IIa, IIb and III graded on sensory loss and motor deficit, and the shared author and shared roman numerals make the two easy to confuse. They are printed side by side above. The second is that these categories, particularly 5 and 6, have largely been superseded in diabetic foot practice by the SVS WIfI classification, which grades wound, ischaemia and foot infection on three separate axes; WIfI is a sixty-four-cell staging table and is not built in this corpus. This category owns the limb and the named vessel. Risk estimation in somebody with no vascular diagnosis belongs to the pooled cohort equations, the cost of an operation to the Revised Cardiac Risk Index and the AUB-HAS2 index, and central circulatory arithmetic to systemic vascular resistance and mean arterial pressure. The measurement technique decides the number before any threshold does: change the convention and the same limb, artery or aorta returns a different figure. Every threshold and interval here is attributed to the body that publishes it, those bodies disagree with one another, and your own service’s protocol takes precedence over all of them. This page computes a published index or places a finding in a published class. It recommends no action.
Frequently asked questions
What are the Rutherford categories of chronic limb ischaemia?
Grade 0 category 0 asymptomatic; grade I categories 1, 2 and 3 for mild, moderate and severe claudication; grade II category 4 for ischaemic rest pain; grade III categories 5 and 6 for minor and major tissue loss. Each carries an objective haemodynamic criterion, from the 1997 Society for Vascular Surgery reporting standard.
Why does Rutherford category 2 have no numeric criterion?
Because the published standard does not give it one. Its clinical description is increased walking limitation and its objective criterion is that the haemodynamic findings fall between categories 1 and 3. That is the instrument as published, and any claudicating limb that meets neither category 1’s criterion nor category 3’s belongs here.
Why is the post-exercise ankle pressure used rather than the resting one?
Because a resting pressure can be normal or borderline in a limb that claudicates. Collateral flow maintains resting perfusion; exercise raises demand and the distal pressure falls. Category 1 requires a post-exercise pressure above 50 mmHg that is still at least 20 mmHg below resting, and category 3 a post-exercise pressure below 50 mmHg in a patient who cannot finish the test.
Is Rutherford IIb the same as Rutherford category 2 or 3?
No. Rutherford IIb belongs to his separate classification of ACUTE limb ischaemia and means an immediately threatened limb with sensory loss beyond the toes and a mild to moderate motor deficit. Categories 2 and 3 are degrees of chronic claudication. Same author, same roman numerals, different diseases — which is why both tables are on this page.
What if the clinical category and the pressure criterion disagree?
Record both, which is what this page does. The commonest cause is medial arterial calcification raising the measured ankle pressure without raising perfusion, classically in diabetes and chronic kidney disease — which is why the standard offers a toe pressure alongside the ankle pressure, and why the ACC/AHA guideline states that neither the ankle-brachial nor the toe-brachial index is useful for diagnosing chronic limb-threatening ischaemia.
Related calculators
References
- Articl. Rutherford Classification of Chronic Limb Ischemia, reproducing Rutherford RB, Baker JD, Ernst C, et al., J Vasc Surg. 1997;26(3):517–38.
- Andreozzi GM, Arosio E, Martini R, Verlato F, Visonà A. Consensus Document on Intermittent Claudication from the Central European Vascular Forum. Int Angiol. 2008;27(2):93–113.
- National Confidential Enquiry into Patient Outcome and Death. Acute Limb Ischaemia, chapter 3: The severity of acute limb ischaemia. London: NCEPOD, 2025.
- American Academy of Family Physicians. Management of Lower Extremity Peripheral Artery Disease: Guidelines From the ACC/AHA. Am Fam Physician. 2025;112(5).
- Romanos MT, Raspovic A, Perrin BM. The reliability of toe systolic pressure and the toe brachial index in patients with diabetes. J Foot Ankle Res. 2010;3:31.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/