Subtalar foot dislocations
These injuries are uncommon and result from indirect application of significant mechanical force. The pathogenesis involves the simultaneous disruption of anatomical relationships in two joints: the talocalcaneal and talonavicular.
Classification and clinical presentation Lateral, anterior, posterior, and combined displacements are distinguished. In practice, internal and posterointernal dislocations predominate.
- Internal dislocation: the foot deviates medially, adopting a position of supination and varus. The head of the talus is clearly palpable on the dorsal surface, with the displaced navicular bone located medially to it.
- Posteromedial dislocation: visually, the forefoot appears shortened, and the heel appears lengthened.
In both cases, there is pronounced deformity, diffuse tenderness, and complete loss of weight-bearing function.
Management strategy At the prehospital stage, transport immobilization and urgent hospitalization are indicated. It is strictly prohibited to attempt joint reduction without adequate analgesia (general anesthesia, spinal, or regional nerve block) — this provokes progressive edema and trophic disorders. Closed reduction (exemplified by posteromedial dislocation) is performed as follows: the lower leg is flexed to 90°, the foot is grasped by the heel and forefoot, and placed into extreme adduction, supination, and equinus. Traction is then applied with pressure from medial to lateral and pronation while an assistant holds the lower leg. Following successful manipulation, a plaster cast is applied for 3–4 weeks. In case of failure, emergency surgery is indicated.
Dislocations in Chopart's joint
Anatomically, Chopart's joint is formed by the proximal and distal rows of the tarsus. Displacement occurs in the talonavicular and calcaneocuboid articulations due to forced rotation (abduction or adduction) of the forefoot.
Most frequently, a dorsomedial dislocation is diagnosed, in which the distal segment displaces dorsally and medially. Clinically, this manifests as sharp pain, inability to bear weight on the limb, and a characteristic prominence of the navicular bone.
Treatment algorithm:
- Prehospital care: analgesics and a posterior splint from the toes to the upper third of the lower leg.
- Closed reduction: performed urgently under anesthesia. In dorsomedial displacement, one assistant fixes the lower leg and heel while a second applies traction to the forefoot. The surgeon presses the tarsus medially, the heel laterally, and corrects the dorsal displacement by pressing on the navicular bone.
- Immobilization: plaster cast for 8–10 weeks.
- Rehabilitation: physical therapy, physiotherapy, and mandatory use of arch supports (orthotic insoles) for at least a year.
If closed reduction fails, surgical open reduction is performed with transarticular fixation using Kirschner wires (removed in 2–3 weeks).
Dislocations in Lisfranc's joint
This anatomical zone represents the articulation between the distal tarsal row and the metatarsal bases. A specific feature of these dislocations is that they are almost invariably accompanied by fractures of the bony structures.
Mechanism and types of displacement The injury occurs from a direct impact or a fall onto the forefoot. Dislocations are classified into:
- Complete (all metatarsal bones are displaced) and incomplete.
- By displacement vector: dorsal, plantar, lateral, and divergent (when the metatarsal bones diverge in different directions).
The absolute "leader" in frequency is the dorsolateral dislocation, which is combined with a fracture of the base of the second metatarsal bone. The clinical presentation is typical of severe trauma: acute pain, massive edema, and complete inability to step on the foot.
Briefly: answers to topical questions
What specific radiographic lines are evaluated on radiographs to confirm Lisfranc joint injury?
To confirm a Lisfranc joint injury on radiographs, the alignment of the cortical margins of the metatarsal and cuneiform bones is assessed.
- Anteroposterior (AP) view — the medial cortical margin of the base of the 2nd metatarsal bone must align with the medial cortical margin of the intermediate cuneiform bone.
- Oblique view — the medial cortical margin of the 3rd metatarsal bone must align with the medial cortical margin of the lateral cuneiform bone.
Disruption of the axis on the AP view indicates lateral displacement of the metatarsal bone. In occult injuries, weight-bearing standing radiographs must be performed to reveal the displacement.
Class and exam questions
Why is it forbidden to reduce a subtalar dislocation directly at the scene of the injury?
Reduction without adequate anesthesia leads to additional tissue trauma, massive progression of edema, and severe trophic disorders of the foot.
What radiographic pattern is typical for a Lisfranc dislocation?
Most frequently, dorsolateral displacement of the metatarsal bones is identified, accompanied by an avulsion fracture of the base of the second metatarsal bone.
How long must a plaster cast be worn after reducing a dislocation in Chopart's joint?
Immobilization with a plaster cast (from the tips of the toes to the upper third of the lower leg) lasts from 8 to 10 weeks. Thereafter, wearing arch supports is required for at least a year.
What else to study on this topic
- Biomechanics of patellar stability and anatomical prerequisites for its dislocations
- Patellar dysplasia and lateralization as a cause of recurrence
- Classification of traumatic patellar dislocations (lateral, torsional, vertical)
- Surgical techniques for recurrent dislocation: Krogius, Ikonomov, and Movshovich procedures
- Indications for corrective bony osteotomies in patellofemoral joint pathology
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