What Is A Talocalcaneonavicular Dislocation?

Dislocations are generated when there is a separation of two bones in the place where they meet, in a joint.

A joint is the place where two bones connect, allowing movement.

A dislocated joint is a joint where the bones, in this case the foot bones are no longer in their normal position, this can happen due to a sudden movement where the stabilizers of that joint (tendons and ligaments) did not support the tension, allowing the bones move.

In the following entries on our blog, the Mediprax clinical team shares information about dislocations that can occur in the foot . On this occasion we will talk about talocalcaneonavicular dislocations.

The most common cause is high-energy trauma. Associated fractures have a high incidence, the most frequent being the talus, the head of the talus, the fibular malleolus, the tibial malleolus, and the base of the fifth metatarsal.

When the doctor explores the area, an important deformity is seen at the ankle and foot level , with functional impotence and without presenting skin lesions or distal vascular-nerve alterations.

Mechanism of injury in dislocations

To rule out a fracture, the doctor requests an x-ray and perhaps in some cases a computed tomography; If there is suspicion of a nerve or blood vessel lesion, this study can help to accurately visualize this.

Subtalar dislocation or peritalar dislocation is the simultaneous dislocation of the distal joints of the talus. The tibiofibular-talar and calcaneal-cuboid joints remain intact. The dislocation can occur in any direction and always produces severe deformities. These are classified into four types: medial, lateral, posterior and anterior. The predominance is absolute for medial peritalar dislocation. The foot is displaced medially with the calcaneus, the scaphoid is medial, and the head of the talus.

Calcaneo-navicular dislocation, also known as subtalar dislocation or periastragalin dislocation, is a rare entity and very short series are presented. Smith found seven cases among 535 dislocations of all types, which accounted for 1.3% and for Pennal it represents 15% of all talus injuries.

Duch published a bilateral case. The most frequent etiological factors are: traffic accidents, falls and work accidents. Grantham published five peritalar dislocations that occurred during basketball practice and defines this injury as a basketball foot.

The position of the foot when acting the traumatic force determines one or another type of dislocation. Medial dislocation, which is the most frequent, originates when a vertical force acts when the foot is in inversion and plantar flexion. Associated fractures have a high incidence. Sanz found associated fractures in 55% of medial dislocations and in 100% of bilateral dislocations.

Treatment should be carried out as soon as possible, avoiding unnecessary delays that only lead to complications, such as edema and necrosis of the skin overlying the talar head.

Foot deformity after dislocation

Knowing the mechanism and type of injury, the doctor will proceed to the reduction with closed orthopedic maneuvers under general anesthesia.

Particular cases require open reduction. This is due to imputation of the medial border of the talar head to the lateral scaphoid and/or interposition of bone fragments or soft tissue. There are factors that darken the prognosis such as the delay in performing the reduction, skin necrosis, infection, open dislocations and associated fractures.

The incidence of avascular necrosis is surprisingly rare; however, in the long term, radiology and clinical findings show that the result is worse than expected, with subtalar osteoarthritis 72% and talonavicular osteoarthritis, some degree of pain when walking 70%, more or less pronounced lameness 50% and loss of subtalar mobility in all published cases.

On examination, a significant deformity was observed at the ankle level, with functional impotence and without presenting skin lesions or distal vascular-nerve alterations. Given the great post-reduction talonavicular instability, temporary fixation with a needle is performed in surgical cases. The limb is immobilized with a posterior splint and off-load is maintained for about 10 weeks. Six months after surgery, the patient walks fully loaded with a slight limp and reports occasional discomfort.

After this process, in the recovery period, it is suggested that as soon as the patient begins to perform support, an analysis of the plantar pressures is carried out by means of the baropodometric study , in order to know the areas of greatest load, it is very normal that the gait and plantar support are altered, in the first instance when the patient supports the foot it can be painful and therefore modify the posture seeking compensation.

Orthopedic insoles are an excellent alternative to maintain the position of the foot , since many patients after this injury can have flat feet due to a distension of the plantar fascia.

 

by Abdullah Sam
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