Calcaneonavicular coalition
Calcaneonavicular coalition is one of the two most common subtypes of the tarsal coalition, the other being talocalcaneal coalition. As with any coalition it may be osseous (synostosis), cartilaginous (synchondrosis) or fibrous (syndesmosis).
Radiographic features
This type of coalition is more easily diagnosed on plain film than talocalcaneal coalition.
Plain radiograph
Oblique view
- best at depicting calcaneonavicular coalition directly as a calcaneonavicular bar
AP view
- may also directly show the coalition
- indirect signs include
- the broad proximal surface of navicular: broader than the articulating talar head
- lateral tapering of navicular
Lateral view
Indirect signs include:
- anteater sign: an elongated anterior process of the calcaneus
- reverse anteater sign: elongated lateral navicular
- talar beak
- short talar neck
CT
CT can be used to confirm the diagnosis where this was equivocal or not seen on plain films. It may also be used for surgical planning.
MRI
MRI is probably more helpful in assessing and characterizing cartilaginous and fibrous coalition and allows assessment of associated bone and soft tissue edema.
Treatment and prognosis
As with any tarsal coalition, non-operative management may allow some improvement in symptoms initially, but they usually return. Usually, surgical treatment with excision of the coalition is required.
Related Radiopaedia articles
Anatomy: Lower limb
- skeleton of the lower limb
- joints of the lower limb
-
hip joint
- ligaments
- muscles
- additional structures
- hip joint capsule
- zona orbicularis
- iliotibial band
-
hip bursae
- anterior
- iliopsoas bursa (iliopectineal bursa)
- lateral
- subgluteal bursae
- greater trochanteric bursa (subgluteus maximus bursa)
- subgluteus medius bursa
- subgluteus minimus bursa
- gluteofemoral bursa
- subgluteal bursae
- postero-inferior
- anterior
- ossification centers
-
knee joint
- ligaments
- anterior cruciate ligament
- posterior cruciate ligament
- medial collateral ligament
- lateral collateral ligament
- meniscofemoral ligament (mnemonic)
-
posterolateral ligamentous complex
- arcuate ligament
- patellar tendon and quadriceps tendon
- anterolateral ligament
- posterior oblique ligament
- oblique popliteal ligament
- medial patellofemoral ligament
- additional structures
- extensor mechanism of the knee
- groove for the popliteus tendon
- knee bursae
- anterior bursae
- medial bursae
- lateral bursae
- posterior bursae
- knee capsule
- lateral patellar retinaculum
- medial patellar retinaculum
- menisci
- pes anserinus (mnemonic)
- ossification centers
- ligaments
- tibiofibular joints
-
ankle joint
- regional anatomy
- medial ankle
- lateral ankle
- anterior ankle
- ligaments
- medial collateral (deltoid) ligament
- lateral collateral ligament
- additional structures
- ankle bursae
- ossification centers of the ankle
- variants
- regional anatomy
- foot joints
-
subtalar joint
- articulations
- ligaments
- associated structures
- mid-tarsal (Chopart) joint
-
tarsometatarsal (Lisfranc) joint
- ligaments
- intermetatarsal joint
- metatarsophalangeal joint
- interphalangeal joint
- ossification centers
-
subtalar joint
-
hip joint
- spaces of the lower limb
-
muscles of the lower limb
- muscles of the pelvic group
- inner hip group
- gluteal region
- lateral rotator group
- muscles of the thigh
- muscles of the leg
- anterior compartment of the leg
- posterior compartments of the leg
- lateral compartment of the leg
- muscles of the foot
- dorsal muscles
- plantar muscles
- 1st layer
- 2nd layer
- 3rd layer
- 4th layer
- accessory muscles
- muscles of the pelvic group
- vascular supply of the lower limb
- innervation of the lower limb
- lymphatic system of the lower limb
- lymphatic pathways
- anteromedial group
- anterolateral group
- posteromedial group
- posterolateral group
- lower limb lymph nodes
- lymphatic pathways
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