Ankle fractures can have a multiplicity of outcomes

Fractures around the ankle joint are common in clinical trauma practice. They also figure quite commonly in a medicolegal practice – not only in personal injury, but also sometimes in clinical negligence work. In this primer, orthopaedic surgeon Mr Nikhil Shah provides a brief outline of ankle fractures.

[THE ANKLE JOINT is also called as the talo-crural joint. It is basically a tenon-and-mortise joint consisting of the distal part of the tibia and the fibula which articulate with the talus – a bone of the foot. The tibia and fibula act as a mortise and form a notch in which the body of the talus fits, acting as the tenon.

The distal part of the tibia is referred to as the plafond. On the inside of the ankle joint the mortise is formed by the medial malleolus –part of the tibia – and on the outer side by the lateral malleolus, the end part of the fibula.

Functionally, it can be regarded as a hinge joint. The main movement at the ankle joint is to allow dorsiflexion and plantar flexion of the foot. It also allows some other types of movements which are referred to as pronation and supination combined with adjacent subtalar and midtarsal joints. The ankle gains its stability not only from the shape of the bones, but also from important ligaments that provide stability circumferentially around the ankle joint.

Causes and types of fractures

The ankle is an important weightbearing joint. It is commonly injured in different types of accidents such as trips and slips, falls from height, cycling or motorcycling accidents, high speed vehicular accidents and sporting injuries among others. Simple trips and slips tend to figure commonly in a fracture clinic. The mechanism can also be a low energy trivial twisting injury in older and frail patients.

There are many different types of ankle fractures. They might affect a single malleolus, or they may be bimalleolar or trimalleolar fractures. Based on the level of the fracture affecting the fibula, ankle fractures can be classified using the Weber classification system. That also gives an idea about the stability of an ankle fracture. Another important classification system looks at the mechanism by which the fracture is caused. That is called the Lauge Hanson classification system.

Ankle fractures can also be associated with injury to the ligaments around the ankle joint. Sometimes there are focal injuries to the cartilage, which are referred to as osteochondral injuries.

Open ankle fractures

Some high-energy ankle fractures are associated with significant soft tissue injury to the skin and surrounding soft tissue. It may be seen as a direct open cut to the skin, resulting in exposure of the bone to the external environment. That is called an open fracture. However, skin injuries can also occur in the form of degloving, extensive blistering or swelling.

Ankle fracture dislocations are associated with a dislocation of the talo-crural joint. That can be a potentially life-threatening injury, especially in patients with diabetes. Treatment can be very challenging. Such injuries can be associated with compromise to the nerve supply or blood supply to the foot. There is also a risk of compartment syndrome.

In such ankle injuries it may not be possible to perform open reduction internal fixation. They may need to be treated using external fixation. That consists of a system of long screws which are anchored to the healthy bone above and below the fracture and connected to each other using a system of rods and clamps to form a scaffold outside the ankle.

Importance of diagnosis in trauma practice

Ankle fractures can be associated with a long-term risk of secondary post-traumatic arthritis. That is determined by the severity of the initial injury and extent of damage to the cartilage of the tibia or the talus. Appropriate diagnosis and management of ankle fractures therefore becomes important. The injury affects a weightbearing joint and hence the treatment revolves around obtaining a good quality reduction followed by stable internal fixation to obtain as good an outcome as possible.

Medicolegal implications

Principles of treatment

Not all fractures need surgery. Stable fractures that are undisplaced can be managed without surgery. In some of those fractures, early weightbearing can also be allowed either in a boot or in a plaster cast.

Unstable fractures or fractures that cause a step in the articular surface often need open reduction and internal fixation. That consists of making a surgical incision over the fracture and fixing it with the help of plates and screws. These fractures appear commonly in personal injury reports. Not all ankle fractures are necessarily associated with good longterm outcomes. It is recognised that some of them may result in persistent pain or loss of movement. A common question asked is regarding the long-term risk of arthritis following an ankle fracture. In clinical negligence practice, ankle fractures may figure in breach of duty allegations relating to a missed diagnosis or inappropriate surgical management Bimalleolar ankle fracture treated with ORIF – open reduction internal fracture or perioperative care. q www.yourexpertwitness.co.uk 55 55