Elsevier

Orthopaedics and Trauma

Volume 24, Issue 4, August 2010, Pages 286-297
Orthopaedics and Trauma

Trauma
Malleolar ankle fractures. A guide to evaluation and treatment

https://doi.org/10.1016/j.mporth.2010.03.010Get rights and content

Abstract

Malleolar ankle fractures are commonly encountered in orthopaedic trauma practice. The goal for treatment of these injuries is to maximize function and minimize complications. The treatment programme is based on the nature of osseoligamentous and soft tissue injury, the functional requirements of the patient and the overall medical condition of the patient. Non-operative treatment is usually reserved for stable fractures of the lateral malleolus; unstable bimalleolar and trimalleolar injuries are usually treated operatively. Staged treatment with initial external fixation and delayed definitive internal fixation is utilized to avoid soft tissue complications in high energy injuries. The Danis–Weber and Lauge-Hansen classification systems are useful for systematic diagnosis and formulation of a treatment plan of specific fracture patterns and ligamentous injuries. Definitive operative treatment is focused on the restoration of the anatomy of the ankle mortise. Injury to the medial malleolus and medial ligaments, the fibula, the syndesmosis and the posterior malleolus are addressed sequentially. The postoperative rehabilitation programme is designed based on the severity of the injury and the patient profile.

Introduction

The ankle joint – the articulation between the tibia, tibula and talus – is what we stand on and what allows us to propel forwards when standing up. It is surrounded by bone prominences, the malleoli, which keep the joint in track. Ankle fractures are breaks in the malleoli, which can allow the talus to sublux from under the tibia and thereby make walking difficult and painful. This article is about malleolar fractures. These injuries are most commonly low energy fractures caused by rotation of the body around the planted foot. True fractures of the distal tibia articular surface or ‘pilon’ and fractures of the talus are fractures of the ankle joint but these are not the injuries we are writing about, and the algorithms for their treatment are different.

The goals for treatment of ankle fractures depend greatly on patient profile. A soccer-playing teenager needs more function than a sedentary octogenarian. A 10-point functional rating of the ankle gives a quick estimate of the effects of therapy; allocates four points for pain and two each for swelling, stability, and stiffness.1 So a good ankle never hurts, is not stiff, does not give way and never swells. A solidly fused ankle also does not hurt, does not swell and does not give way. The fused ankle is always stiff so it rates an 8. If the treatment of a fractured ankle leads to chronic pain, intermittent swelling, and instability (five points), then the treatment is no better than an ankle fusion. The goal of this paper is to provide insights on how to care for this demanding injury in order to achieve results that are good.

There are three malleoli – the medial malleolus, lateral malleolus, and posterior malleolus (also called Volkmann's triangle). The simplest way to classify ankle fractures is to count the number of fractured malleoli. When a single malleolus is broken one speaks, for example, of fracture of the medial malleolus; when more malleoli are fractured then the injury is a bimalleolar or trimalleolar fracture. This classification is the used in AMA's Current Procedural Terminology (CPT) for billing in the United States, since the actual complexity of ankle fractures would otherwise overwhelm hospital clerks.

In rotational injuries, external rotation of the talus in relation to the tibia separates the fibula from the tibia, tearing the interconnecting syndesmotic ligaments. The more proximal the fracture of the fibula the greater is the injury to the syndesmosis and the worse the prognosis. This is the basis of Weber's classification2 which is based on the level of the fracture of the fibula. Fractures of the fibula distal to the tibial plafond are in Weber zone A, those at the level of the tibio-fibular joint in Zone B and those more proximal in Zone C. The antero-inferior tibio-fibular ligament binds the fibula to the tibia at Chaput's antero-lateral tubercle. This ligament is intact in Weber A fractures, variably damaged in zone B fractures and usually torn in Zone C fractures of the fibula.

The classification of Lauge-Hansen is based on a laboratory experiment.3 The intelligent management of ankle fractures requires an understanding of Lauge-Hansen's work. Lauge-Hansen took amputation specimens and fastened them to a fixture. He then positioned the foot in either pronation (sole down and externally rotated) or supination (sole up and internally rotated.) Then he smartly snapped the ankle to cause a fracture and dissected the specimen. In Lauge-Hansen's binomial classification the first name is how the foot was held and the second which way the fracturing force was directed. Thus in supination – external rotation the foot was first held in supination and then turned outward to break the ankle. The dissections of the fractured specimens yielded consistent clusters of injuries, which correspond to the vast majority of fractures occurring in patients. Remember it was only an experiment, and remember that if you try this in the shower by twisting on a planted foot your body turns inward the ankle is actually turning outward relative to your torso. Lauge-Hansen describes stages for the major patterns of ankle fractures. The stage is a measure of how far the talus turned in the mortise and indicates the injures to be looked for in the clinical situation. For example, as the talus turns outward in pronation-external rotation the first stage is the fracture of the medial malleolus. The second stage is tearing of the antero-inferior tibio-fibular ligament and fracture of the fibula in Zone C and so forth.

In working with Lauge-Hansen it is important to remember the concept of equivalent injuries. Thus a tear of the deltoid ligament is equivalent to a fracture of the medial malleolus. In this respect mechanically similar injuries may fall into different groups if the malleolar fracture counting classification is used instead of the Lauge-Hansen classification. Details about the Lauge-Hansen system and Weber's classification follow.

Section snippets

Anatomic considerations

The anatomic structures which confer the ankle joint its stability are both bony and ligamentous. They maintain the talus centred correctly underneath the tibia and allow controlled motion. The malleoli (medial, lateral and posterior) are the bony protuberances which keep the talus in its groove. The motion at the ankle joint is predominantly in the sagittal plane and consists of dorsiflexion and plantarflexion. During physiologic motion plantarflexion is associated with slight internal

Injury assessment

In order to make decisions about the treatment of ankle fractures multiple factors need to be evaluated. These include the mechanism of injury, medical and social condition of the patient, status of the soft tissues and vasculature, and radiographic studies.

Most rotational ankle fractures occur through relatively low energy mechanisms, such as simple falls and sports injuries. However, sometimes high energy mechanisms, such as a motor vehicle accident or a fall from height, causes the injury

The Danis–Weber classification2

The Danis–Weber classification system differentiates the ankle injury based on the location of the fibula fracture. The ankle fractures are divided into three categories: A, B, and C. The injury to the medial structures is not addressed in this classification.

Type A injury: the fracture of the fibula is located at the level of the tibial plafond or distal to it. The orientation of the fracture line is transverse. The syndesmotic ligaments are intact.

Type B injury: the fracture of the fibula is

The Lauge-Hansen classification

The Lauge-Hansen classification3 was devised to delineate the mechanisms, pathologic anatomy and radiographic basis for the diagnosis and reduction strategies of ankle fractures. The fractures were produced experimentally in amputated limbs at the Central Hospital in Randers, Denmark. Each limb was fixed via vice grip and nails and then a deforming force was applied by hand. As the force was applied to the limb the fractures and ligament tears occurred in stages, as the displacement was

Non-operative treatment

Ankle fractures can be successfully treated non-operatively. The key to obtaining good results is selecting injuries that will respond well to non-operative treatment. These are generally isolated fractures of the lateral malleolus. The talus must be maintained in the correct position in the mortise in order to restore ankle joint function once the fracture ultimately heals. The evidence from in vitro biomechanical studies suggests that the talus position will be maintained when the lateral

Postoperative care

The postoperative programme is adapted to the stability of the ankle joint, and thus depends on the energy of injury, the condition of the tissues, the classification of the fracture and the patient profile. On the one hand a really stable injury, such as a low energy pronation grade 1 fracture of the medial malleolus repaired with lag screws, can be placed in a walking cast and begun on immediate weight bearing. An unstable fracture–dislocation, for example supination-external rotation grade

Conclusion

Ankle fractures are common but are not to be underestimated. They form a major portion of musculoskeletal trauma practice. Most patients recover with satisfactory, if imperfect, results. Poor results are consequences either of unsolved biological problems or poor technique. The former are wonderful areas for future investigation, the latter are mostly avoidable. For example, how can we restore the syndesmotic ligament complex? The healing of ligaments is imperfect. Or what treatment is

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