Stuck in the Middle: Imaging
Overview of the Midtarsal
Chopart Joint
Zoe Doyle, MD1, Michelle Nguyen, MD1,2
1Stanford Hospital and Clinics
2VA Palo Alto Healthcare System

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Disclosures

The authors have no conflicts of interests to disclose related to thispresentation.

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Objectives
1. Review the anatomy of Chopart joint
2. Discuss mechanisms of Chopart injuries
3. Review multimodality imaging findings of
Chopart injury
4. Discuss treatment options

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Overview
1. The Chopart joint complex connects the hindfoot andthe midfoot
2. 20-40% of Chopart injuries are initially missed, dueto:• Variable clinical presentation• Clinical confusion with other types of ankle injury, which commonly
accompany Chopart injuries• Radiologists’ unfamiliarity with Chopart joint injuries• Underestimation of the ligamentous component of injury

3. Missed Chopart complex injuries can lead toprolonged swelling, pain, and disability, and canoccasionally lead to acquired flatfoot

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Chopart Anatomy Overview
Highly mobile joint complex which
joins the hindfoot and the midfoot
Consists of two joints
Calcaneocuboid (lateral column)
Talonavicular (medial column)
Lisfranc

Function• Works in conjunction with subtalar
joints to invert and evert the foot• Provides pivotal motion of thehindfoot while the forefoot remains
stationary• Stabilizes the midfoot during thepush-off phase of the gait cycle

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Chopart

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Osseous Structures
Gently curved Cyma lines (shown in red) demonstrate the normal
relationship of the Chopart joint osseous structures on lateral and AP
foot radiographs

T
N
Cu

Ca
Cu

N
T
T – talus
N – navicular
Ca – calcaneus
Cu – cuboid
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OsteonecrosisCaLigamentous Structures
Talonavicular (TN)• Stabilizes the talonavicular joint• Dorsal aspect of the talar neck to thedorsal navicularTN

Bifurcate• Stabilizes the talonavicular andcalcaneocuboid joints• Y-shaped structure with 2 components:

BifurcateMedial calcaneonavicular ligament
From the anterior calcaneal process to
the lateral navicularCC

Lateral calcaneocuboid ligament
From the anterior calcaneal process tothe dorsal cuboid

Dorsal calcaneocuboid (CC)
• Stabilizes the calcaneocuboid joint• Dorsolateral aspect of the calcaneus to
the dorsal cuboid
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Ligamentous Structures
Plantar ligaments• Stabilize the calcaneocuboid joint• Extend from the plantar aspect of
calcaneus to plantar cuboid• Long and short components

Short plantar ligament
From anterior calcaneal tubercle tothe posterior plantar surface of the
cuboid and cuboid beakLong plantar

Long plantar ligament
From anterior calcaneal tubercle andthe intertubercular segment of theposterior calcaneal tuberosity, withdeep fibers (most of the ligament)
going to the cuboid crest and somesuperficial fibers inserting on thesecond to fifth metatarsal bases
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Short plantar

Ligamentous Structures
Spring ligament complex:• Static stabilizer of the medial longitudinalarch of the foot and talonavicular joint• Comprised of three bundles:
Superomedial (SM)Sustentaculum tali to dorsomedial
navicular tuberosity

IPL
MPO

Medioplantar oblique (MPO)
Coronoid cavity of anterior calcaneus tobeak of navicularInferoplantar longitudinal (IPL)
Anterior to middle calcaneal facet to beakof navicular
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Normal MR Imaging

TN
BifurcateCC

The bifurcate and talonavicular (TN) ligaments are low tointermediate signal structures best seen on sagittal plane.
Normal patients can have a thickened TN ligament;
therefore, a thickened TN ligament in isolation may notnecessarily be a result of injury.
Sagittal T2 FS images from two different patients show the
cuboidal and navicular components of the bifurcate
ligament (red arrows). The talonavicular ligament isindicated by the blue arrow.

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Dorsal Calcaneocuboid Ligament:
Normal MR Imaging

EDB
CC

TN
BifurcateCC

CC

The dorsal calcaneocuboid (CC) ligament is best seen on axial plane (axial T2 FS MRI on
the left). Anatomic variants are common, including multiple bands, fusion with thebifurcate ligament, and meniscoid variant. EDB=extensor digitorum brevis muscle
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Plantar Ligaments:
Normal MR Imaging
B

A

The plantar ligaments are best seen on
sagittal plane.
Long plantar

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Short plantar

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Sagittal T1 MR images show the (A)long plantar ligament (red arrow) and(B) short plantar ligament(arrowheads).
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Spring Ligament Complex:
Normal MR Imaging
The superomedial bundle is a hammock-like structure that supports the talar head. It is best seen on axial
and coronal planes. While the superomedial bundle should always be seen, the other two components ofthe spring complex (medioplantar oblique and inferoplantar longitudinal) are not as reliably visualized.

IPL

*

*

*

A

MPO

C

B

Normal spring ligament. (A) Axial T2 FS shows the superomedial bundle (arrow) between the talar
head and the posterior tibial tendon (asterisks). (B) Coronal T2 FS showing the superomedial bundle(arrows) supporting the talar head (asterisk). (C) The medioplantar oblique (MPO) and inferoplantar
longitudintal (IPL) bundles have a striated appearance and are best seen on axial T2 FS.
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Chopart Joint Injuries: Overview
Most common mechanism of injury is ankle inversion, with or without plantar
flexion• Varus force can result in calcaneocuboid ligament injury• Superimposed plantar flexion can cause tear of the talonavicular ligament
and there may be impaction at the plantar calcaneocuboid joint

Types of Injuries• Chopart fracture-dislocations• Chopart ligamentous sprains +/- fracture

Imaging Modalities
XR: Evaluation of bony alignment; look for normal Cyma line
Small avulsion fracture fragments may be seen
CT: Primarily for evaluation of fractures
May identify additional fractures not visible on XR
MR: Evaluation of marrow edema and ligamentous injury

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Chopart Joint Injuries:
Fracture-Dislocations
Fracture-dislocations typically result from high force mechanisms such as motor
vehicle collisions or fall from height.
Main and Jowett Classification: Based on injury mechanics
Type

Mechanism

Resulting injury

Medial*Medial force to the forefootDorsal edge fractures of the navicular and talar head,“swivel” dislocation disrupting the talonavicular joint,
medial dislocation with fracture of the body of thenavicular

Axial*

Longitudinal force along the axis of the first ray

Navicular central fracture along the borders of thecuneiforms, often with disruption of the talonavicular
ligament with dorsal displacement of the navicular

LateralLateral force to the forefootCuboid fracture, anterior calcaneal fracture

PlantarFlexion force on the forefootDorsal navicular and talar fractures, anterior process
calcaneal fracture, talonavicular and calcaneocuboid
dislocations, talonavicular and talocalcaneal dislocation

Crush

Random high velocity and high energy forces

No consistent pattern* Medial and axial injuries are more common
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Chopart Joint Injuries:
Fracture-Dislocations
Zwipp Classification: Based on affected anatomic structures
Six types:
Transligamentous
TransnavicularTranscuboidal
Transcalcaneal
Transtalar
Combined (any combination of theabove, except for transligamentous)
Image originally published in Rammelt S and Schepers T. Chopart Injuries: When toFix and When to Fuse? Foot Ankle Clin N Am, 2017.

• More commonly used than Main and Jowett• Purely transligamentous dislocation is rare due
to strong support at the TN and CC joints• The navicular and cuboid are more frequently
fractured than the more proximal bones

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Chopart Joint Injuries:
Example of Fracture-Dislocation

A

B

CB.

D

Chopart fracture-dislocation. Normal Cyma line for comparison (A). Disrupted Cyma linewith dislocated talonavicular and calcaneocuboid joints on lateral ankle radiograph (B). AP footradiograph (C) in the same patient again shows abnormal alignment of the Cyma line. (D)Sagittal CT image in the same patient shows subluxation and widening of the talonavicular
joint.
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Chopart Joint Injuries:
MRI Findings
Common bone marrow edema patterns
Location of edema
Plantar talar head

Tears of the spring ligament and attachment sites of thebifurcate and calcaneocuboid ligaments

Dorsal talar head

Talonavicular ligament avulsion

Lateral anterior calcaneal
process
Medial calcaneocuboid joint

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Frequently associated injury

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Calcaneocuboid and/or bifurcate ligament avulsion
Short plantar ligament avulsion

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Chopart Joint Injuries:
MRI Findings
Retrospective review of 47 patients who
obtained ankle MRI within 8 weeks ofan acute ankle injury
Acute or subacute Chopart joint
ligament injury seen in 17% of patients
Most common mechanism of injury: Ankle inversion
Most common ligament injured: Dorsal calcaneocuboid ligament
Bone marrow edema: seen in 100%
Most common site of marrow edema: Plantar talar head
Fracture: seen in 50%
Most common fracture sites: Dorsal talar head = Anterior calcaneal process > Lateral cuboid
75% had concurrent lateral ankle ligament sprains (at least grade 2)
45% had concurrent deltoid ligament sprains
64% of all Chopart injuries (include acute, subacute, and chronic) had edema of the extensor digitorum
brevis muscle

In the initial radiology reports, acute or subacute Chopart ligament injuries were
missed in 83% of cases
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Let’s review what we’ve learned.

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Case 1: 64 F with fall and twisting inversion
injuryA

B

Sag PD FS

Talonavicular ligament injury. (A) Lateral radiograph shows avulsion fractures of thenavicular and talus (blue arrows). (B) Tear of the talonavicular ligament (red arrow), withavulsion fracture and marrow edema of the dorsal talus (yellow arrow).

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Case 1: 64 F with fall and twisting inversion
injury (continued)

C

Ax PD FSD

Sag PD FS

Calcaneocuboid ligament tear. (C) Complete tear of the calcaneocuboid ligament isshown. (D) Mild plantar talar head marrow edema is also present. Notice the failed fat
saturation in the mid and distal foot in these images.

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Case 2: 33 M with inversion injury
Bifurcate andcalcaneocuboid ligament
tears. (A) Sprain of theA

Sag T2 FS

B
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Ax T2 FS

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Sag T2 FS

D

Sag T2 FS

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lateral calcaneocuboid
ligament (component of
the bifurcate). (B) Tear of
the calcaneocuboid
ligament with associatedmarrow edema in thelateral calcaneus.
Nondisplaced fracture of
the calcaneal process(yellow arrow, C) andedema of the plantar talar
head (blue arrow, D).

Case 3: 34 year old female with fall

A

B

*

Sag PD FS

C*

Plantar ligament injury with cuboid avulsion fracture. (A) Lateral radiograph

Sag PD FS

demonstrates a fracture at the plantar aspect of the cuboid. (B) and (C) show the avulsion
fracture at the cuboid crest (yellow arrow) and tear of the long plantar ligament at the cuboid
attachment (blue arrowhead). The peroneus longus tendon is indicated by the asterisk.

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Case 3: 34 year old female with fall(continued)

InitialAx PD FS

D

E

Follow-up
Ax PD FS

Extensor digitorum brevis edema. (D) There is partial calcaneocuboid ligament tear(arrow) with adjacent extensor digitorum brevis edema (arrowheads). (E) MRI performed 2
months later for persistent pain better demonstrates the ligamentous tear (arrow). Extensor
digitorum brevis edema is decreased but persists (arrowheads).
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Case 4: 77 F with insidious onset pain and swelling for
1 weekA

Sag PD FS

B

Sag PD FSC

Ax PD FS

Talonavicular and calcaneocuboid ligament injury. Plantar subluxation of the talus withtearing of the talonavicular ligament (A, red arrow). Note the marrow edema in the dorsal
navicular (A, yellow arrow) and medial talus at the head/neck junction (B, blue arrow). (C)Additional tearing of the calcaneocuboid ligament at the cuboid attachment was present.

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Case 4: 77 F with insidious onset pain and swelling for
1 week (continued)

D

Cor T2 FS

E

Ax PD FS

Spring ligament injury. (D) Coronal and (E) axial images showing high grade tear of thesuperomedial bundle of the spring ligament complex (arrows). Marrow edema is again seen in
the talar head (arrowheads).

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Case 5: 34 F with history of a twisting injury

A

B

Ax T2 FS

Dorsal calcaneocuboid injury. (A) AP radiograph shows an avulsion fracture of the

distal lateral calcaneus at the attachment site of the dorsal calcaneocuboid ligament (redarrow). (B) MRI shows the dorsal calcaneocuboid ligament tear with adjacent calcaneal
marrow edema at the site of bony avulsion (yellow arrow).
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Case 5: 34 year F with history of a twisting
injury (continued)
DC

Sag PD FS

Plantar ligament injury. MRI showing

Ax T2 FS

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sprain of the short plantar ligament(blue arrows in C and D) and adjacentbone marrow edema in the cuboid(yellow arrow in C).

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Case 5: 34 year F with history of a twisting
injury (continued)

E

Sag T2 FS

F

Sag PD FS

GBifurcate ligament injury. (E) MRI shows intermediate signal and sprain of the medial

Sag PD FS

calcaneocuboid ligament, which is a part of the bifurcate ligament (red arrow). (F) Note theadjacent mild marrow edema in the dorsal proximal cuboid (yellow arrow). (G) Marrow edemais also seen in the plantar talar head (yellow arrow).

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Case 5: 34 year F with history of a twisting
injury (continued)

H

Ax T2 FSICor PD FS

Concurrent lateral and medial ankle sprains. (H) Bone marrow edema is seen within thelateral malleolus at the attachment of the anterior talofibular ligament (not pictured here). (I)There is also sprain of the deltoid ligament (red arrow) and associated edema within the medial
malleolus (blue arrow).
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Treatment
Nonoperative: Stable fractures/sprains• No dislocation or displaced fracture fragments• Treated with immobilization with progressive weightbearing. Example injuries
include:Ø Extra-articular bony avulsion fractures
Ø Impacted articular fragments of the lateral column (more forgiving than the medialcolumn, which is more load bearing)Ø Inaccessible fractures such as plantar navicular and plantar medial aspect of the
cuboid, for which the benefit of ORIF is not proven

Operative: Unstable fractures/dislocations• All displaced fractures and dislocation• Goal of surgery is to restore normal joint alignment• Needs to be reduced as soon as possible to prevent further damage to the soft
tissues• Primary fusion of the CC or TN joints should be reserved for cases of severe
destruction of the articular surface, due to the important roles of these joints
in global foot function

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Treatment Options:
ExamplesNonoperative treatment. Small

avulsion fractures at thetalonavicular joint located outside
the joint space, with normalalignment of the talonavicular joint.
This was treated nonoperatively
with weight bearing as tolerated,
and the patient was given a CAM
walker boot to use as needed.
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B

A

Operative treatment. Pre reduction (A) and post
reduction (B) images of talonavicular joint
dislocation. Compare the relative alignment of thetalus and navicular before and after fixation with K
wires.
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Take Home Points• The Chopart joint complex is a midtarsal foot joint connecting thehindfoot and midfoot, and consists of the talonavicular andcalcaneocuboid joints• Chopart joint injuries are frequently overlooked and may clinically bemasked by concurrent ankle injuries• Knowledge of the anatomy of the Chopart joint and recognition of
Chopart injuries is important to preventing prolonged pain, disability,and potentially acquired flatfoot deformity• Clues that may indicate Chopart joint injury include concurrent injuries
to the lateral ankle ligaments or deltoid ligament, and extensor
digitorum brevis edema• Operative management is needed for unstable injuries in which there
is displaced fracture or dislocation
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