Cuneiform Fractures

Cuneiform fractures are rare but important injuries of the medial, intermediate or lateral cuneiform, three of the midfoot bones, which sit between the navicular and the metatarsals and form part of its stability. A displaced fracture is fixed to restore midfoot stability, but stability, articular congruity and column length decide treatment more than a generic 2mm rule does.

How rare. Cuneiform fractures are usually quoted at less than 1% of foot fractures, with a peak at 20-40 years in the trauma population and no clear gender predominance. Those are conventional teaching estimates for midfoot trauma; no cuneiform series exists to measure them, and fewer than 10 isolated medial cuneiform fractures have been reported (Paisan 2017). The sourced demographics on this page belong to the Lisfranc population, which is more frequently male and in the third decade (Mascio 2022).

Mechanism. High-energy midfoot trauma, often by a Lisfranc mechanism, or direct trauma to the midfoot.

The Lisfranc association. The medial cuneiform anchors the medial column and the Lisfranc ligament complex, so a cuneiform fracture suggests midfoot instability. It may be isolated or part of a broader tarsometatarsal or intercuneiform injury, and other midfoot trauma may accompany it. The association is strong but unquantified: no series has measured how often the two coexist, so do not quote a figure, and treat a cuneiform fracture as a Lisfranc injury until proven otherwise.

The three bones. Each articulates with the navicular and with its own metatarsal:

• Medial cuneiform - the largest; articulates with the navicular, first metatarsal and intermediate cuneiform
• Intermediate cuneiform - the smallest, recessed in the mortise between the medial and lateral; articulates with the navicular, second metatarsal and both other cuneiforms
• Lateral cuneiform - articulates with the navicular, third metatarsal, intermediate cuneiform and cuboid

The ligaments. The Lisfranc ligament attaches to the medial cuneiform and spans to the second metatarsal, and with the cuneiforms it maintains midfoot alignment. It sits within a ligament network that links the tarsometatarsal, intermetatarsal and intercuneiform joints. A cuneiform fracture can therefore destabilise more than one column or articulation.

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Why displacement matters. Displacement, articular incongruity, column shortening and dynamic instability can lead to collapse or arthritis. Displacement causes midfoot instability, instability causes midfoot collapse, and malunion leads to midfoot arthritis. The medial cuneiform is the keystone of the medial column, so a malunion there shortens or angulates the whole ray.

Cuneiform fractures are described by the bone involved, by displacement and by whether a Lisfranc injury accompanies them.

By bone. The bone guides the approach and the search for associated injury.

An isolated intermediate cuneiform fracture should prompt a search for a Lisfranc injury, and a lateral cuneiform fracture means assessing the cuboid and lateral column at the same time. No comparative outcome data exist for any of the three, so do not quote a success rate by bone.

By displacement. The conventional split is a step-off of less than 2mm (non-displaced, treated conservatively) against more than 2mm (displaced, treated by ORIF). That 2mm is the generic intra-articular convention, extrapolated from Lisfranc and other intra-articular foot injuries; no cuneiform series has tested any cut-off.

What carries across. What the Lisfranc literature does support, and what transfers to the cuneiform, is that instability matters more than the millimetre: a fracture that displaces on weight-bearing or stress views needs fixation whatever the static step-off measures.

By Lisfranc association. An isolated cuneiform fracture receives cuneiform-specific treatment; a cuneiform fracture with a Lisfranc injury needs both injuries addressed.

History. Midfoot pain after high-energy trauma, with swelling localised to the midfoot and pain on weight bearing. A Lisfranc injury mechanism and midfoot instability are the risk factors to establish.

Examination. Look for midfoot swelling, ecchymosis (which may be delayed) and, if the fracture is displaced, deformity from midfoot collapse. The cuneiforms are tender; the Lisfranc joint is tender as well if that injury is associated. Midfoot movement is limited and painful, and inversion and eversion hurt. Three checks complete it:

• Lisfranc stress test - midfoot instability
• Midfoot stress - pain on stress
• Midfoot alignment - collapse

Radiographs. Three views, each of which may show the fracture:

• AP - check for a Lisfranc injury
• Lateral - midfoot alignment
• Oblique - may show the fracture better, and is the Lisfranc joint view

When it is safe, weight-bearing or stress comparison views assess the instability that a static CT cannot show.

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CT. CT is usually required for diagnosis and planning. It is recommended when a cuneiform fracture is suspected, when a Lisfranc injury is associated and when surgery is planned, and it shows the fracture pattern, the displacement (measure the step-off), any Lisfranc injury and the midfoot alignment.

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The painful, swollen midfoot after trauma has a wide differential. The single most important distinction is whether the cuneiform fracture is isolated or a component of a Lisfranc injury, because that decision changes both stability assessment and fixation strategy.

The differential of a "cuneiform fracture" on imaging must include the bipartite medial cuneiform, a congenital normal variant that is the classic mimic and a well-recognised cause of over-diagnosis.

What it is. The bone forms as two ossicles, a dorsal and a plantar half, separated by a cartilaginous synchondrosis. It is uncommon, roughly 1% or fewer of feet, and is often bilateral.

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Telling it from a fracture. The dividing line of a bipartite cuneiform is smooth, rounded and corticated on both sides and lies in a consistent plane, usually horizontal, dorsal to plantar. An acute fracture line is sharp, non-corticated and irregular, with adjacent bone-marrow oedema on MRI and a matching mechanism and point tenderness. Bilaterality and corticated margins point to the variant.

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Why it matters. Misreading a bipartite cuneiform as a fracture leads to needless immobilisation or surgery. Conversely, a genuinely symptomatic bipartite cuneiform, a painful synchondrosis, is a separate and uncommon entity. When in doubt, compare the contralateral foot and use MRI: oedema indicates an acute injury or a symptomatic synchondrosis, not an incidental variant.

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The decision. Determine stability rather than assuming every medial fracture needs fixation. Map the whole midfoot first, with the radiographs, CT and weight-bearing or stress views described above, and identify every involved articulation.

Stable: protect and follow. A closed, isolated, acceptably aligned fracture with no dynamic Lisfranc or intercuneiform instability, no column shortening and no threatened skin can be treated in a boot or short-leg cast, according to comfort and stability. Mobilise with protected or non-weight-bearing loading at first.

Progression. Progress loading from clinical improvement and radiographic healing rather than a universal 6-8-week rule; the duration depends on pain, healing, the fracture pattern and patient factors. Published outcomes are at case-report level, and persistence or loss of alignment requires renewed imaging and reconsideration.

Unstable: reconstruct the pattern. Consider fixation or reconstruction for:

• Open fracture or threatened soft tissue
• Dynamic midfoot instability or associated Lisfranc disruption
• Unacceptable articular incongruity, displacement or column shortening
• Symptomatic nonunion or failed maintenance of alignment

The construct must restore the involved rays and joints, not merely compress one fracture line. Timing follows the soft-tissue condition, urgency, associated injuries and reduction stability; there is no universal two-week window.

Reassess. Follow symptoms, weight-bearing capacity, serial alignment and union. CT is reserved for unresolved pain, occult displacement, nonunion concern or operative planning.

Algorithm

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The pattern. A high-energy midfoot injury, from a crush or a road traffic accident, can comminute all three cuneiforms with dislocation of the medial three metatarsals and disruption of the Lisfranc ligament: the transcuneiform fracture-dislocation. CT is essential to map the comminution and plan the reconstruction.

The goal. Reconstruction aims to restore the length and alignment of the medial and middle columns and the longitudinal and transverse (diagonal) arches of the foot. It does not aim to piece together every small cuneiform fragment anatomically; column length is what preserves function.

Approach and fixation. An anterior or dorsal longitudinal approach exposes the cuneiforms and metatarsal bases. K-wires and/or screws across the tarsometatarsal joints, or bridge plating, hold length and alignment while the comminuted bone heals, and primary arthrodesis is considered for irreconstructible articular destruction.

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Reading the numbers. The ranges for instability, collapse and nonunion are conventional teaching figures, not measured rates; no cuneiform fracture series exists to derive them from. The only sourced frequency is the missed-Lisfranc figure (Mascio 2022).

Instability and collapse. An associated Lisfranc injury is a further cause of instability. When either is severe, it is managed by revision ORIF or midfoot fusion.

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After fixation, union decides when the cast comes off and loading begins, which is the situation in which CT is used to confirm it.

What the outcome literature contains. No study has reported the outcome of a series of cuneiform fractures. There is no success rate, no return-to-activity figure and no stability rate for any treatment of this bone, and any percentage quoted for "cuneiform fracture outcome" has been carried over from Lisfranc series or invented. The published numbers, in full, are these:

Counselling. Counsel from mechanism and from the Lisfranc principle, not from a number. An isolated, non-displaced, stable cuneiform fracture is expected to heal and do well. A cuneiform fracture that is part of a tarsometatarsal injury takes the prognosis of that injury, which is materially worse: persistent pain, post-traumatic arthritis and deformity are the recognised outcomes, and anatomical reduction is the single factor consistently associated with doing better.

Tell the patient that, and tell them the evidence for the bone itself is a handful of case reports.

Long-term instability. Progression of midfoot instability is conventionally quoted at 10-15% with proper treatment and 20-30% without, with displacement, Lisfranc injury and delayed treatment as the risk factors. These are teaching figures carried over from the Lisfranc literature, not measurements; the table above shows that no cuneiform cohort exists to derive them from.

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Global Epidemiology

• Isolated cuneiform fractures are among the rarest foot fractures (the isolated medial cuneiform literature comprises fewer than 10 reported cases worldwide).
• Most cuneiform fractures occur as part of a midfoot/Lisfranc injury complex, which is more common in men in the third decade.
• Up to 20% of Lisfranc injuries are missed or diagnosed late globally, the single biggest driver of poor outcomes regardless of healthcare setting.

Guidance Across Major Bodies

There is no cuneiform-fracture-specific society guideline; practice is extrapolated from Lisfranc and general intra-articular foot fracture principles, which are broadly concordant across regions.

Registry and Trial Notes

• Arthroplasty-style joint registries (NJR, AJRR, AOANJRR) do not track cuneiform fractures; the relevant high-level data are the Lisfranc RCTs (Ly & Coetzee 2006; Henning 2009) and the ongoing multicentre BFF trial.
• These consistently show that reduction quality, not the specific implant, determines outcome.

High- vs Limited-Resource Practice

• Well-resourced settings: routine CT for mapping, MRI for occult/ligamentous injury, and a foot-and-ankle subspecialist performing column-based fixation or primary arthrodesis.
• Limited-resource settings: reliance on weight-bearing and stress radiographs with contralateral comparison; closed reduction with percutaneous K-wires or screws is a legitimate strategy when CT and implants are scarce, prioritising anatomic alignment and a stable, plantigrade foot.

Because isolated cuneiform fractures are vanishingly rare, almost every controversy is inherited from the Lisfranc literature that governs the combined injury. The displacement threshold is one; it is dealt with under Classification.

ORIF or primary arthrodesis. For the associated Lisfranc injury, two RCTs (Ly & Coetzee 2006; Henning 2009) favoured primary arthrodesis on AOFAS scores and reoperation rates, particularly for primarily ligamentous patterns. The adequately powered multicentre BFF trial is designed to settle this. Until then, ORIF remains widely used for bony fracture-dislocation patterns where the medial column can be anatomically reconstructed.

Screw or plate. Transarticular screws are simple but damage articular cartilage; dorsal bridge plating spares the joint surface but needs more dissection. No high-level evidence establishes either as superior, and the choice is guided by fracture comminution and surgeon preference.

Hardware removal. Whether to remove transarticular hardware routinely is unresolved. Routine removal inflates the reoperation rate, a major reason arthrodesis looked favourable in Henning 2009, but may relieve symptomatic hardware; many centres now retain or selectively remove.