Introduction
The fracture of the outer ankle (distal fibula fracture = fracture of the lower fibula) is one of the ankle fractures that occur relatively frequently in humans, especially in the context of sports injuries. In more than 80% of cases, an external ankle fracture occurs as a result of a traumatic injury in the form of a dislocation (subluxation or luxation) of the ankle bone from the ankle fork, with which it forms the ankle joint. This is usually caused by a false step or fall, i.e. an ankle injury.
Depending on the position of the foot during the injury and the forces acting on it, different injury patterns can occur. The most common is the classification according to Danis-Weber, which classifies the fractures according to their location in relation to the syndesmosis. The syndesmosis, as a ligament connection, is a fake joint that holds the tibia and fibula together.
An external ankle fracture can be described more precisely with the help of the current AO classification, into which all fracture types can be precisely classified. Regardless of the type of fracture, the prognosis of an external ankle fracture is consistently good. However, a prerequisite is that the bone parts are precisely repositioned in their anatomical, physiological position (reduction).
Conservative therapy
In principle, both conservative (non-operative) and surgical treatment are possible. However, conservative treatment can only be offered as long as the fracture is not displaced (dislocated) and the syndesmosis has not been injured. This is the case, for example, with simple external ankle fractures below the syndesmosis or non-displaced external ankle fractures at the level of the syndesmosis without injury.
The therapy then usually consists of wearing a plaster cast for six weeks. The time until complete healing varies from patient to patient. How much weight can be put on the affected leg after removal of the cast depends on the individual healing process, which the doctor checks by means of X-rays.
As a rule, however, intensively straining sports such as tennis or running may be resumed after about 3 to 6 months. Even with conservative therapy, complications occur, although very rarely, which can significantly delay healing. In a few cases, the fracture may slip (secondary dislocation), which then usually has to be surgically corrected.
Furthermore, wearing the plaster cast can cause pressure damage, which further limits the functionality of the ankle joint. Furthermore, pseudoarthrosis, a false joint, can develop between the fracture parts. A pseudoarthrosis is when, depending on the bone affected, no firm bony connection between the bone fragments has yet been formed months after a fracture.
The consequences are long-lasting pain, functional limitations and abnormal mobility of the respective skeletal part. Sudeck’s disease is another complication that can occur as a result of soft tissue and nerve injuries in the context of the fracture. A largely unknown mechanism leads to an irregular healing process with symptoms such as pain at rest, muscle weakness, tremor, excessive sweating or edema.
These complications, however, occur extremely rarely in the conservative treatment of an external ankle fracture. Complaints such as numbness or swelling may persist for several months, but usually disappear. Chronic complaints such as permanent pain or a functional impairment are not to be expected in the vast majority of cases.
In most cases, however, ankle joint fractures such as the outer ankle fracture must be treated surgically. This includes all displaced outer ankle fractures or fractures in which the syndesmosis has been injured. It is crucial for the success of therapy that the axis, length and rotation of the ankle joint can be restored exactly.
For this purpose, the operation should be performed within the first six hours after the injury. Exceptions are open fractures, which are an emergency indication for surgical treatment, and massive swelling, as a result of which the operation must be postponed for a few days. Depending on the injury pattern, surgical treatment is carried out using screw or plate techniques, or a combination of both.
In this case, a millimetre-exact restoration of the anatomical ankle joint conditions is of great importance, as otherwise the incorrect loading can lead to premature wear and tear of the joint (post-traumatic ankle arthrosis). After the removal of the wound tubes (drains) on the 2nd day postoperatively, the first X-ray control image is usually taken. The stitches are removed after about 10 to 14 days.
If the operation was successful, the patient should be offered early functional follow-up treatment of the external ankle fracture. Functionality and mobility of the ankle joint are operated on while relieving the affected leg. The patient should use crutches for mobilization for at least 6 weeks.
Bed rest including a plaster cast is only necessary in very rare cases. After approx. 6 weeks, after an X-ray check, the load build-up can be started.
In this case, support by physiotherapeutic exercises is highly recommended. After approx. 8 weeks, a fluid gait pattern should be achieved.
After 3 to 6 months at the latest, even intensively strenuous sports such as tennis or running are possible again. After about 1 year, plates and screws are usually removed. In addition to the complications resulting from conservative therapy, surgery can still cause additional delays in healing.
Thus, vessels, tendons or nerves can be injured during the operation. Furthermore, every surgical intervention carries a certain risk of infection, which can drastically limit the healing of the wound and fracture in some cases. In rare cases, implants may become loose and have to be repositioned correctly in a further operation. As the risk of thrombosis or a resulting pulmonary embolism is relatively high, especially in the case of ankle and ankle fractures, adequate thrombosis prophylaxis (e.g. with heparin injections) should be taken both during surgical and conservative treatment. However, all these complications are rare, so that even after surgical treatment of an external ankle fracture, complete healing can be expected.
