OrthoNet

Fractures and Dislocations of the Foot - Midfoot Injuries

Reference: Heckmann, James, in Rockwood and Green, 1996, Chapter 32

Main Message

These are often overlooked injuries that require a keen index of suspicion.

Points of Interest

Chopart’s Joint

Biomechanically designed to allow for flexibility of the midfoot on heelstrike, then rigidity on toe-off; when the subtalar joint is everted (on heelstrike) the talonavicular and calcaneocuboid joints are parallel, allowing some motion at the midtarsal joint. When the foot rolls into toe-off, the subtalar joint inverts and the talonavicular and calcaneocuboid joints diverge, locking the midtarsal joint and creating a rigid lever upon which to push off.fs

5 mechanisms of injury (Main and Jowett, JBJS 57B, 1975)
- Medial stress injury (most common) - severe inversion of the foot
- Longitudinal stress injury - severe force applied longitudinally from distal to proximal to the metatarsal heads with the foot plantarflexed - pushes up the rays into the navicular and cuneiform, which fracture. The navicular tends to fracture in line with the cuneiforms.
- Lateral stress injury - eversion injury, with a crush to the cuboid or anterior calcaneus as the forefoot is driven laterally (nutcracker fracture of the cuboid), with possible avulsion off the navicular.
- Plantar stress injury - plantarly directed force pushes the navicular and cuboid down, often avulsing the dorsal lip.
- Crush injury - for all those other unclassified injuries.

Treatment

- needs diagnosis first! These are often missed!
- if undisplaced - cast x 6 weeks
- if displaced, frequently need ORIF with K-wires or screw fixation.
- arthrodesis down the road for residual disability; some favor primary arthrodesis, but most would recommend trying to fix as best as possible first.

Navicular Fractures

- Cortical Avulsion
- Tuberosity
- Body

Cortical Avulsion
- avulsion of the talonavicular capsule and anterior fibers of teh deltoid ligament with eversion
- treat with splinting, then walking cast 4-6 weeks; If large, fix them to restore congruity of the talonavicular joint.

Tuberosity Fragment
- avulsion of the tib post tendon by acute eversion of the foot.
- make sure it is not an accessory navicular
- treat nondisplaced with walking cast, 4-6 weeks. If significant proximal displacement occurs, fix them immediately to restore length of the tib post tendon. If nonunion and pain persist, then excise them.

Body Fractures
- can be in the coronal plane, or in a sagital plane with displacement of the foot in a medial or lateral direction
- undisplaced fractures get casting, the rest should be reduced and fixed.
- the key is to recognize the whole injury to the foot, of which the navicular fracture may be just one manifestation of (ie - midtarsal dislocation, Lisfranc injury, etc..)

Stress Fracture
- look out in large, heavy basketball players
- treat with non-weightbearing cast for 6-8 weeks; may take 6 months to heal!

Cuboid Injuries
- most commonly, a “nutcracker” fracture from being forced between the anterior process of the calcaneus and the 5th metatarsal.
- when undisplaced, short leg walking cast x 6 weeks
- if severe shortening of the lateral column, may need to bone graft, +/- arthrodesis of the calcaneocuboid joint.

* when looking at fractures in the navicular, cuboid, or cuneiforms, look at the foot as a whole - how did the fracture occur? What were the forces? Is there a more extensive ligamentous injury from a subluxation or dislocation of the midtarsal or Lisfranc joint?

Lisfranc Injuries (Tarsometatarsal)

- intrinsic stability is provided primarily by the bony architecture - the second metatarsal locks into the space between the medial and lateral cuneiforms.
- transverse metatarsal ligaments holds the heads together, and the 4 lateral bases are similarly held together; “Lisfranc’s ligament” is an especially strong structure extending from the medial cuneiform to the