Cuneiform Fractures

Cuneiform fractures are rare but important injuries involving the medial, intermediate, or lateral cuneiform bones of the midfoot. These fractures are often associated with Lisfranc injuries and require ORIF if displaced to restore midfoot stability.

Definition

Cuneiform fracture: Fracture of the medial, intermediate, or lateral cuneiform, which:

• Location: Midfoot, between navicular and metatarsals
• Function: Part of midfoot stability
• Association: Often with Lisfranc injuries
• Treatment: ORIF if displaced

Cuneiform bones:

• Medial cuneiform: Most common, Lisfranc ligament attachment
• Intermediate cuneiform: Rare, often with Lisfranc
• Lateral cuneiform: Rare, isolated or with Lisfranc

Epidemiology

• Incidence: Less than 1% of foot fractures
• Age: Peak 20-40 years (trauma population)
• Gender: No clear predominance
• Mechanism: High-energy trauma, midfoot injury
• Associated injuries: Lisfranc injuries (30-40%), other midfoot trauma

Cuneiform Anatomy

Cuneiform bones:

• Medial cuneiform: Largest, articulates with navicular, 1st metatarsal, intermediate cuneiform
• Intermediate cuneiform: Smallest, articulates with navicular, 2nd metatarsal, medial and lateral cuneiforms
• Lateral cuneiform: Articulates with navicular, 3rd metatarsal, intermediate cuneiform, cuboid

Midfoot stability:

• Cuneiforms: Part of midfoot stability
• Lisfranc ligament: Attaches to medial cuneiform
• Function: Maintains midfoot alignment

Lisfranc association:

• Medial cuneiform: Lisfranc ligament attachment site
• Midfoot instability: Cuneiform fracture suggests instability
• 30-40% association: With Lisfranc injuries

Pathophysiology

Injury mechanism:

• High-energy trauma: Midfoot injury
• Lisfranc mechanism: Often associated
• Direct trauma: To midfoot

Why displacement matters:

• Midfoot instability: Displacement causes instability
• Arthritis risk: Malunion leads to midfoot arthritis
• Collapse risk: Instability causes midfoot collapse

Why ORIF required:

• Restore stability: Anatomic reduction restores midfoot stability
• Prevent collapse: Prevents midfoot collapse
• Lisfranc: Often requires addressing both injuries

History

Symptoms:

• Midfoot pain: Pain in midfoot
• Swelling: Localised to midfoot
• Difficulty weight bearing: Pain with weight bearing
• Mechanism: High-energy trauma

Risk factors:

• High-energy trauma
• Lisfranc injury mechanism
• Midfoot instability

Physical Examination

Inspection:

• Swelling on midfoot
• Ecchymosis (may be delayed)
• Deformity (midfoot collapse if displaced)

Palpation:

• Tenderness over cuneiforms
• Lisfranc joint tenderness (if associated)
• Midfoot instability

Range of Motion:

• Midfoot ROM limited and painful
• Inversion/eversion painful

Special tests:

• Lisfranc stress test: Check for midfoot instability
• Midfoot stress: Pain with stress
• Midfoot alignment: Check for collapse

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. In a bipartite (partitioned) medial cuneiform 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.
• How to tell it from a fracture. The dividing line of a bipartite cuneiform is smooth, rounded and corticated on both sides and lies in a consistent (usually horizontal, dorsal-to-plantar) plane, whereas 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.
• 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, 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.

Beyond the isolated hairline fracture, the cuneiforms can be shattered as part of a high-energy transcuneiform fracture-dislocation — a pattern the evidence base describes but the body does not develop.

• The pattern. A high-energy midfoot injury (crush, road traffic) can comminute all three cuneiforms with dislocation of the medial three metatarsals and disruption of the Lisfranc ligament — the "transcuneiform" fracture-dislocation.
• The goal is the column and the arch, not the fragment. Reconstruction aims to restore the length and alignment of the medial and middle columns and the longitudinal and transverse (diagonal) arches of the foot, rather than to anatomically piece together every small cuneiform fragment — column length is what preserves function.
• Approach and fixation. An anterior/dorsal longitudinal approach exposes the cuneiforms and metatarsal bases; fixation is by K-wires and/or screws across the tarsometatarsal joints (or bridge plating) to hold length and alignment while the comminuted bone heals, with primary arthrodesis considered for irreconstructible articular destruction.
• Imaging. CT is essential to map the comminution and plan reconstruction of these complex injuries.

Midfoot Instability

10-15% incidence (if untreated):

• Cause: Displacement, inadequate reduction, Lisfranc injury
• Prevention: Anatomic reduction, adequate fixation
• Management: Revision ORIF or midfoot fusion if severe

Midfoot Collapse

10-15% incidence (if untreated):

• Cause: Midfoot instability, inadequate fixation
• Prevention: Restore stability, adequate fixation
• Management: Revision ORIF or midfoot fusion if severe

Immediate Postoperative

• Immobilisation: Short leg cast or boot
• Weight bearing: Non-weight bearing (6-8 weeks)
• ROM: Ankle ROM after cast removal
• PT: Midfoot ROM and strengthening

Rehabilitation Protocol

Weeks 0-6:

• Short leg cast, non-weight bearing
• Elevation to reduce swelling
• Ankle ROM exercises (if stable)

Weeks 6-8:

• CT to confirm healing
• Cast removal if healing
• Transition to walking boot
• Progressive weight bearing

Weeks 8-12:

• Full weight bearing
• Progressive activity
• Return to sport (3-4 months)

Overall Outcomes

ORIF (isolated):

• Success rate: 80-85% (union, pain relief)
• Functional outcomes: 75-80% return to pre-injury level
• Midfoot stability: 80-85% maintain stability

ORIF (part of Lisfranc):

• Success rate: 75-85% (union, pain relief)
• Functional outcomes: 70-75% return to pre-injury level
• Midfoot stability: 75-80% maintain stability

Conservative (non-displaced):

• Success rate: 85-90% (union, pain relief)
• Functional outcomes: 80-85% return to pre-injury level
• Midfoot stability: 85-90% maintain stability

Long-Term Prognosis

Midfoot instability progression:

• With proper treatment: 10-15% develop instability
• Without treatment: 20-30% develop instability
• Risk factors: Displacement, Lisfranc injury, delayed treatment

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.