Image Quiz

An Unusual High-Energy Injury to the Ankle (continued)

Answer: Fracture dislocation of the ankle with anteriorly dislocated tendons preventing closed reduction.

Anteroposterior and lateral radiographs revealed a superior and central dislocation of the ankle, with an intact tibia and a high fibular fracture approximately 10 cm proximal to the joint line (Figs. 1-A and 1-B). With the patient under sedation, another unsuccessful attempt at reduction was made by the orthopaedic staff. It was thought that there was a fixed bone block to relocation, with the talus wedged between the tibia and the fibula.


Fig. 1-A
Fig. 1-B		 Figs. 1-A and 1-B Preoperative anteroposterior (Fig. 1-A) and lateral (Fig. 1-B) radiographs of the fracture-dislocation.

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The patient was then taken immediately to the operating room for further management. After the patient was anesthetized, closed reduction was once again attempted, without success. To facilitate reduction, the ankle joint was first opened anteromedially, with the superficial skin abrasion avoided as much as possible. A large hematoma evacuated spontaneously. The deltoid ligament and the medial tendon sheaths were found to be ruptured, and the tendons of the posterior tibial, flexor digitorum longus, and flexor hallucis longus muscles were found to be dislocated anteriorly into the joint, thus blocking the distal distraction of the talus and the reduction of the dislocation (Fig. 2). The neurovascular bundle remained behind the medial malleolus.


Fig. 2		 Fig. 2 Schematic drawing depicting the position of the talus and the posterior tibial, flexor hallucis longus, and flexor digitorum longus tendons.

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Because the reduction was still difficult, the lateral side of the ankle was also opened, through a posterolateral approach. A large posterior malleolar fragment from the distal aspect of the tibia (a Dupuytren fragment) could be palpated. The posterior tibiofibular ligament remained attached to this fragment, which, in retrospect, could be seen lying superior to the talus, between the separated fibula and tibia, on the anteroposterior radiograph (Fig. 1-A). From the lateral side, the tibia appeared to be rotated forward in relation to the fibula, with the talus jammed between the two.

By placing a retractor around the tendons from the medial side and applying pressure laterally to disengage the talus from the fibula by pushing the talus anteriorly and distally and by applying distal traction, it was possible to reduce the ankle joint. The ankle was then irrigated, and no additional osseous fragments were found.

Fixation was achieved with two syndesmosis screws placed from the lateral side. A partially threaded cancellous screw was then placed through the distal aspect of the tibia into the posterior malleolar fragment percutaneously from the front. Stress radiographs made in the operating room at this point showed the ankle to be stable. The deltoid ligament was repaired with absorbable sutures, and the skin was closed subcutaneously over a drain. A plaster splint was applied with the ankle in a neutral position to rest the tissues. Postoperatively, the limb was elevated on a Bohler-Braun frame and the patient was given antibiotics for prophylaxis against infection.

Forty-eight hours after surgery, the ankle was inspected on the ward. There was little swelling, and the skin over the medial malleolus appeared viable. A full below-the-knee cast was applied, and the patient was allowed to walk with the aid of crutches without bearing weight on the affected ankle. Radiographs of the ankle in the plaster cast (Figs. 3-A and 3-B) demonstrated persistent good alignment of the ankle joint.


Fig. 3-A
Fig. 3-B		 Figs. 3-A and 3-B Anteroposterior (Fig. 3-A) and lateral (Fig. 3-B) radiographs of the ankle in a plaster cast, made one week after the injury.

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Six months after the injury, the patient had full range of movement of the ankle joint and was able to perform all of his usual activities, including sports activities and riding a motorcycle.

Discussion

This injury proved to be difficult to treat. To disrupt the syndesmosis as it did, the pattern of injury must have involved both axial loading and a rotatory force, which usually would result in a pilon type of fracture pattern. To our knowledge, a superior and central fracture-dislocation pattern has not been reported previously in the literature.

Ankle fractures that involve entrapped tendons have been described previously in the literature. It was not possible to reduce the fracture in our patient because the anteriorly dislocated tendons were applying a lateral force on the tibia and wedging the talus between the tibia and fibula. Only with use of a medial approach to identify and release these tendons with a retractor while simultaneously levering the talus inferiorly and anteriorly from the lateral side was it possible to reduce the fracture-dislocation. After reduction, the tendency was for the tibia and fibula to diverge; hence, we chose to stabilize the fibula to the tibia with two syndesmosis screws as well as to fix the posterior malleolar fragment percutaneously.

Early reduction and evacuation of the tense hematoma was possible within two hours after the injury and relieved the pressure on the compromised skin. The prompt reduction and decompression probably minimized postoperative complications, such as swelling and blistering, that would have been expected from what was definitely a high-energy injury.

In retrospect, a closed reduction of this injury was never likely to succeed. The presence of the posterior malleolar fragment on the original anteroposterior radiograph perhaps should have alerted us to this possibility. A computed tomographic scan may have helped identify this fragment and its position, whereas a magnetic resonance imaging scan would have identified the position of the displaced soft tissues. However, the performance of either of these investigations might have delayed the definitive treatment of this injury and increased the risk of postoperative soft-tissue complications. The posterolateral incision permitted easy access to the fibula and the back of the talus and allowed us to lever the talus forward while retracting the dislocated tendons through the medial incision. We recommend immediate surgical reduction and fixation of this type of injury pattern with use of a two-incision approach.

Reference

1. Adla DN, Hutchinson RJ, Scott IR. An unusual fracture-dislocation of the ankle: a case report. J Bone Joint Surg Am. 2004;86:2287-9.