Fractures and Dislocations of the Foot – Midfoot Injuries
Reference: Heckmann, James, in Rockwood and Green, 1996, Chapter 32
These are often overlooked injuries that require a keen index of suspicion.
Points of Interest
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.
– 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.
– 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.
– 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.
– 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..)
– look out in large, heavy basketball players
– treat with non-weightbearing cast for 6-8 weeks; may take 6 months to heal!
– 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
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