Weber Ankle Fracture Classification
Weber Ankle Fracture Classification
Classify an ankle fracture Weber A, B or C from the level of the fibular fracture — and see why a system built on bone is being used to report a ligament that the radiograph cannot show.
Weber type from the fibular fracture level
Fibular level + medial side + clear spaceA spiral fibular fracture at the level of the syndesmosis with a medial malleolar fracture, on a standard non-weight-bearing series showing no clear space widening
Three letters, one bone
- the letter comes from the fibula and nothing else
- the medial malleolus, the deltoid ligament and the posterior malleolus do not enter the letter. A report that gives only “Weber B” has discarded the medial side, which is why this page asks for it and prints it separately
- the ligament the film cannot show
- types B and C “imply a degree of damage to the syndesmosis itself (which cannot be directly visualised on X-ray)”. The inference runs from the level of a bony fracture to the state of a ligament, and in type B it is widening on STRESSED views that suggests injury — so a normal standard series has not settled it
- how high a type C can be
- the fibular fracture “may arise as proximally as the level of fibular neck”. A standard ankle series does not include the fibular neck, so a Weber C can be radiographically invisible on the films taken
- agreement, for once, is reasonable
- eight observers (two first-year, two second-year and two third-year residents and two preceptors) on 20 radiographs: overall kappa 0.69 (0.63 to 0.76), and by letter A 0.71, B 0.73, C 0.65. The same study gave Lauge-Hansen 0.64 overall but 0.12 (0.04 to 0.20) for its pronation-abduction subtype — so the three-letter system is reproducible precisely because it asks one visible question
- no AO/OTA subdivision here
- the B1/B2/B3 and C1/C2/C3 subdivisions belong to the AO/OTA compendium, which is copyright Lippincott Williams & Wilkins and which the OTA’s own page says “cannot be used commercially or for-profit without permission of the publisher”. This page carries the three Danis-Weber letters and stops
- derivation
- attributed to Danis and to Weber and reproduced in McRae R and Esser M, Practical Fracture Treatment 5th ed, p382, which is the source Wikipedia’s reproduction cites. Neither original was reachable for this page, so the criteria here are quoted from Radiopaedia and from that reproduction, which agree
Worked example
A spiral fibular fracture at the level of the syndesmosis with a medial malleolar fracture, on a standard non-weight-bearing series showing no clear space widening
A fibular fracture is present, so the classification applies
The fibula is broken at the level of the syndesmosis, so this is neither A nor C
The clear space is not widened on the views available, so the answer is Weber B
Note what the letter has not recorded: the medial malleolar fracture does not change it, because Weber is assigned from the fibula alone
Change the views to a series with no stressed, gravity or weight-bearing film and the answer becomes Weber B, syndesmosis not assessed — the same bone, and an honest statement that the question the letter raises has not been answered
Move the fibular fracture above the syndesmosis, keeping the medial malleolar fracture, and it is Weber C with a medial injury. Move it below, keeping the widening, and the page says the findings do not fit a Weber A rather than assigning one
The three letters as the sources describe them
| Type | Fibular fracture | Syndesmosis | Medial side | Stability as described |
|---|---|---|---|---|
| A | “below the level of the syndesmosis (infrasyndesmotic)”, usually transverse | “tibiofibular syndesmosis intact” | “deltoid ligament intact”; medial malleolus “occasionally fractured” | “usually stable if medial malleolus intact” |
| B | “distal extent at the level of the syndesmosis (trans-syndesmotic); may extend some distance proximally”, usually spiral | “intact or only partially torn, but no widening of the distal tibiofibular articulation”; widening on stressed views suggests injury | “medial malleolus may be fractured or deltoid ligament may be torn” | “variable stability” |
| C | “above the level of the syndesmosis (suprasyndesmotic)”; “may arise as proximally as the level of fibular neck” | “disrupted with widening of the distal tibiofibular articulation” | “medial malleolus fracture or deltoid ligament injury present” | “unstable: usually requires ORIF” |
Agreement, and the comparison that puts it in perspective
| Classification | Kappa (95% CI) | Observers and images |
|---|---|---|
| Danis-Weber, overall | 0.69 (0.63 to 0.76) | 8 observers — two first-year, two second-year and two third-year residents and two preceptors — on 20 radiographs |
| Danis-Weber, type A | 0.71 (0.63 to 0.80) | same |
| Danis-Weber, type B | 0.73 (0.65 to 0.82) | same |
| Danis-Weber, type C | 0.65 (0.57 to 0.73) | same |
| Lauge-Hansen, overall | 0.64 (0.58 to 0.70) | same |
| Lauge-Hansen, supination-external rotation | 0.76 (0.67 to 0.84) | same |
| Lauge-Hansen, pronation-abduction | 0.12 (0.04 to 0.20) | same |
| Lauge-Hansen, supination-adduction | 0.79 (0.70 to 0.87) | same |
A bony landmark standing in for a ligament
Weber sorts ankle fractures by one question: where did the fibula break relative to the tibiofibular syndesmosis? Below it is type A, at it type B, above it type C. The three letters are quick to apply, they are reproducible — eight observers reading 20 radiographs reached kappa 0.69 overall, with 0.71, 0.73 and 0.65 for A, B and C — and they are used everywhere. For a classification of fractures that is a good record.
What the letters are actually for is a different matter. The reason the fibular level is interesting is that it predicts the state of the syndesmosis, and therefore whether the ankle mortise will hold. Types B and C, as the standard reproduction of the criteria puts it, imply a degree of damage to the syndesmosis itself — which cannot be directly visualised on a radiograph. So the system runs an inference from a bone it can see to a ligament it cannot, and the inference is weakest exactly where most fractures sit. Type A is described as usually stable if the medial malleolus is intact, type C as unstable, and type B — the commonest — as having variable stability. For type B, widening of the tibiofibular joint on stressed views is what suggests syndesmotic injury, which means a standard non-weight-bearing series that looks normal has not answered the question at all.
That is why this page asks separately about the medial side and about which views were available, and why one of its answers is “Weber B, syndesmosis not assessed”. The letter is assigned from the fibula alone, so a report that gives only the letter has discarded the medial malleolus, the deltoid ligament and the posterior malleolus — and in type A the conditional about the medial malleolus is doing most of the work in the stability statement.
One further practical point. A type C fibular fracture may arise as high as the fibular neck, and a standard ankle series does not include it. A patient with ankle pain, a widened medial clear space and no fracture on the ankle films may have a Weber C that is simply outside the field of view. The AO/OTA subdivisions of B and C are not reproduced here, because that compendium’s publisher restricts commercial use of the scheme; the three Danis-Weber letters are where this page stops.
A classification is not a score. Garden IV is not one unit worse than Garden III, a Salter-Harris IV is not twice a II, and nothing on this page adds up — these are named categories, not an ordinal measurement, and a mean or a difference taken over them has no meaning. This page states which published category the entered findings fall in and what the literature reports for that category in the cohorts it was measured in. It renders no clinical or surgical decision: not whether to operate, not which implant, not whether to take or withhold an image, and not whether a limb can take weight. Those are the treating clinician’s, and the classification is one input among many. Agreement between observers is part of what a classification means. A category two experienced readers assign differently on the same film is not a measurement of the fracture, and the published kappa values for these systems run from almost nothing to almost perfect. Each page here prints them with the number of observers and the number of radiographs they came from.
Frequently asked questions
What are the Weber ankle fracture types?
Type A is a fibular fracture below the level of the tibiofibular syndesmosis, with the syndesmosis and deltoid ligament intact. Type B is at the level of the syndesmosis, which is intact or only partially torn without widening of the distal tibiofibular articulation. Type C is above the syndesmosis, with the syndesmosis disrupted and the tibiofibular articulation widened; the fibular fracture may be as high as the fibular neck.
Does a Weber type tell you whether the ankle is stable?
Not on its own. The published descriptions call type A usually stable if the medial malleolus is intact, type C unstable, and type B variable — and type B is the commonest. The letter is assigned from the fibula alone and says nothing about the medial malleolus or the deltoid ligament, and the syndesmosis it is being used to predict cannot be directly visualised on a radiograph. Stability is a clinical judgement, usually needing stressed, gravity or weight-bearing views.
How reliable is the Weber classification?
Better than most fracture classifications. Eight observers — six residents at three levels and two preceptors — reading 20 radiographs reached an overall kappa of 0.69 (95% CI 0.63 to 0.76), with 0.71 for type A, 0.73 for type B and 0.65 for type C. The same observers reading the same radiographs reached 0.64 for Lauge-Hansen overall, but only 0.12 for its pronation-abduction subtype.
Why is my Weber C not visible on the ankle radiographs?
Because a type C fibular fracture can arise as proximally as the fibular neck, and a standard ankle series does not reach it. A widened medial clear space or medial tenderness with no fracture on the ankle films is the pattern that should prompt imaging of the whole fibula. What is done about it is a clinical decision and not one this page makes.
Where are the B1, B2 and C1 subtypes?
They belong to the AO/OTA Fracture and Dislocation Classification Compendium, which is copyright Lippincott Williams & Wilkins. The Orthopaedic Trauma Association’s own page for it states that the classification may be used for research, educational and medical purposes without permission but cannot be used commercially or for-profit without the publisher’s permission, so no part of that scheme is reproduced here.
Related calculators
References
- Radiopaedia. Weber classification. Type A “below the level of the syndesmosis (infrasyndesmotic)” with “tibiofibular syndesmosis intact”, usually transverse, deltoid intact, medial malleolus occasionally fractured, “usually stable if medial malleolus intact”. Type B “distal extent at the level of the syndesmosis (trans-syndesmotic); may extend some distance proximally”, usually spiral, syndesmosis usually intact but widening on stressed views suggesting syndesmotic injury, “variable stability”. Type C “above the level of the syndesmosis (suprasyndesmotic)”, “fracture may arise as proximally as the level of fibular neck”, syndesmotic disruption with widening of the distal tibiofibular articulation, “unstable”.
- Wikipedia, Danis–Weber classification, citing McRae R and Esser M, Practical Fracture Treatment, 5th ed, p382. Type A “Fracture of the fibula distal to the tibiofibular syndesmosis”, “tibiofibular syndesmosis intact”, “deltoid ligament intact”. Type B “Fracture of the fibula at the level of the syndesmosis”, “tibiofibular syndesmosis intact or only partially torn, but no widening of the distal tibiofibular articulation”, “medial malleolus may be fractured or deltoid ligament may be torn”. Type C “Fracture of the fibula proximal to the syndesmosis”, “tibiofibular syndesmosis disrupted with widening of the distal tibiofibular articulation”, “medial malleolus fracture or deltoid ligament injury present”. And the limitation this page is built around: types B and C “imply a degree of damage to the syndesmosis itself (which cannot be directly visualised on X-ray)”.
- de Paula Neto AC, Ikeuti DH, Santos AB, Barroco RS, Miranda BR, Macedo RR. Análise de concordância das classificações das fraturas de tornozelo do adulto [Concordance analysis of adult ankle fracture classifications]. Sci J Foot Ankle. 2019;13(1):10–14. Eight observers (two first-year, two second-year and two third-year residents and two preceptors) and 20 radiographs. Overall kappa: Danis-Weber “0.69 (0.63-0.76)”, Lauge-Hansen “0.64 (0.58-0.70)”. By Danis-Weber type: “Tipo A 0.71 0.63 – 0.80”, “Tipo B 0.73 0.65 – 0.82”, “Tipo C 0.65 0.57 – 0.73”. By Lauge-Hansen subtype: SRE 0.76, PRE 0.63, “PAB 0.12 0.04 – 0.20”, SAD 0.79.
- Orthopaedic Trauma Association. Fracture and Dislocation Compendium, ota.org/research/publications. The compendium is “© 2018 Lippincott Williams & Wilkins”; the classification and its figures may be reproduced for research, educational and medical purposes “without the need to request permission from the OTA, AO Foundation or the publisher”, but “It cannot be used commercially or for-profit without permission of the publisher”, with requests through the Journal of Orthopaedic Trauma’s rights and permissions process. That is why this page carries A, B and C and no AO/OTA subdivision.
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