bubble_chart Overview

The joint surface of the ankle is smaller than that of the hip and knee joints, yet it bears significant weight and activity, making it prone to injury. It accounts for 3.83% of all fractures in the body and is more common in adolescents.

bubble_chart Etiology

Inversion (adduction) type fracture

can be divided into III degrees.

Degree I: simple medial malleolus fracture, the fracture line runs obliquely upward and medially from the lower articular surface of the tibia, nearly vertical.

Degree II: with greater violence, while the medial malleolus suffers an impact fracture, the lateral malleolus suffers an avulsion fracture, known as bimalleolar fracture.

Degree III: with greater violence, while the medial and lateral malleoli fracture, the talus impacts the posterior margin of the tibia, resulting in a posterior malleolus fracture (trimalleolar fracture).

Eversion (abduction) type fracture

can be divided into III degrees according to the severity of the fracture.

Degree I: simple medial malleolus avulsion fracture, the fracture line is transverse or short oblique, the fracture surface is coronal, mostly without displacement.

Degree II: with continued violence, the talus impacts the lateral malleolus, resulting in an oblique fracture of the lateral malleolus, i.e., bimalleolar fracture. If the medial malleolus fractures while the inferior tibiofibular ligament ruptures, separation of the distal tibia and fibula may occur. At this time, the talus shifts outward, creating a torsional force at the distal fibula above the syndesmotic ligament, resulting in a fracture of the lower 1/3 or middle 1/3 of the fibula, known as Dupuytren fracture.

Degree III: with excessive violence, the talus impacts the posterior margin of the lower articular surface of the tibia, resulting in a posterior malleolus fracture, i.e., trimalleolar fracture.

External rotation fracture

occurs when the lower leg is stationary and the foot is forcibly externally rotated, or when the foot is stationary and the lower leg is forcibly internally rotated. The anterolateral part of the talus compresses the anteromedial part of the lateral malleolus, causing an oblique or spiral fracture of the distal fibula, which can also be divided into III degrees.

Degree I: the fracture has little displacement; if displaced, the distal fracture fragment shifts outward, backward, and externally rotates.

Degree II: with greater violence, the medial collateral ligament ruptures or the medial malleolus suffers an avulsion fracture, i.e., bimalleolar fracture.

Degree III: with severe violence, the talus shifts laterally and externally rotates, impacting the posterior malleolus, resulting in a trimalleolar fracture.

Longitudinal compression fracture

occurs when falling from a height and landing vertically on the heel, which can cause a fracture of the anterior margin of the tibia, accompanied by anterior dislocation of the ankle joint. If the violence is excessive, it may result in a comminuted fracture of the lower articular surface of the tibia.

In cases of severe trauma, when a trimalleolar fracture occurs, the ankle joint completely loses stability and suffers significant dislocation, known as Pott fracture.

bubble_chart Diagnosis

Local swelling, tenderness, and dysfunction. During diagnosis, the mechanism of injury should first be analyzed based on the trauma history, clinical symptoms, and the type of fracture shown on the X-ray.

bubble_chart Treatment Measures

The surface area of the ankle joint is smaller than that of the hip and knee joints, but it bears more body weight than the hip and knee joints. Moreover, the ankle joint is close to the ground, and the weight-bearing stress acting on it cannot be buffered. Therefore, the treatment of ankle joint fractures requires higher standards than other areas. The importance of anatomical reduction in ankle joint fractures is increasingly recognized. If the joint surface is slightly uneven or the joint space is slightly widened after a fracture, traumatic arthritis can occur. Regardless of the type of fracture, the treatment requires that the lower end of the tibia, i.e., the saddle-shaped joint surface of the ankle joint and the talus, must align perfectly. Additionally, the medial and lateral malleoli must restore their normal physiological inclination to accommodate the talus, which is narrower posteriorly and superiorly and wider anteriorly and inferiorly.

Non-displaced fractures

The ankle joint is fixed in a neutral position at 90° dorsiflexion with a lower leg cast. After 1–2 weeks, when the swelling subsides and the cast loosens, it can be replaced once. The cast is generally worn for 6–8 weeks.

Displaced fractures

1. Manual reduction and external fixation

The principle of manual reduction is to apply force in the direction opposite to the injury mechanism, pressing the displaced bone fragments back into place. For example, in the case of an eversion fracture, an inversion posture is adopted, with the foot maintained at 90° dorsiflexion while both hands squeeze the malleoli to reduce the fracture. After reduction, the lower leg is immobilized with a cast for 6–8 weeks.

2. Surgical reduction and internal fixation

The treatment of ankle fractures should aim for anatomical reduction. For cases where manual reduction cannot meet the therapeutic requirements, surgical intervention is often recommended.

(1) Indications a. Failed manual reduction; b. Inversion fractures with a large medial malleolar fragment involving more than half of the tibial articular surface; c. Eversion-external rotation avulsion fractures of the medial malleolus, especially when soft tissue is interposed; d. Large fragments of the anterior tibial articular surface; e. Failed manual reduction of posterior malleolar fractures; f. Trimalleolar fractures; g. Old fractures with secondary traumatic arthritis affecting function.

(2) Surgical principles The general principles are: a. The ankle mortise must be anatomically aligned; b. Internal fixation must be strong enough to allow early functional exercise; c. Bone and cartilage fragments within the joint must be thoroughly removed; d. Surgery should be performed as early as possible.

(3) Methods for fractures at different locations a. Medial malleolar avulsion fractures: Screw fixation is sufficient. If screws cannot achieve stable fixation, Kirschner wires and tension band wiring in a figure-8 pattern can be used for compression fixation. b. Lateral malleolar fractures: Screw fixation can be used. If the fibular fracture is above the level of the syndesmosis or has an oblique fracture line, a plate or compression plate may be used for fixation. c. Posterior malleolar fractures involving one-fourth or one-third of the tibial articular surface are difficult and unstable to reduce manually. Open reduction and screw internal fixation are generally required. d. Dupuytren fractures: A transverse bone bolt can be used to fix the distal tibiofibular joint, and the deltoid ligament should be repaired simultaneously.

bubble_chart Complications

Traumatic arthritis