Operative Versus Non Operative Treatment for Unstable Ankle Fractures

The most controversial ankle fracture is the Weber B fracture in which the fibular (or lateral malleolar) fracture begins at the level of the ankle mortise and extends proximal and lateral. This fracture can exist as isolated fractures of the lateral malleolus, or bimalleolar injuries in which both lateral and medial malleoli are fractured. When both malleoli are fractured, the ankle has lost all of its bony support and is unstable. In contrast, if only the lateral malleolus is injured, the Weber B injury may be either stable or unstable. When the ankle is subluxed or dislocated in these injuries, the ankle is clearly unstable. However, when the ankle is not initially subluxed, the assessment of stability is more difficult. Stability in isolated lateral malleolar fractures depends upon the status of the medial, or deltoid, ligaments. Further complicating matters, the deltoid ligament may be intact, partially torn, or completely torn such that there is a spectrum of stability for these injuries.Previous studies relied upon an assessment of tenderness over the ligament to determine instability, but this may not differentiate between partial and complete tears.

In North America, most surgeons would agree that markedly unstable definitely unstable ankle fractures are best treated surgically.Therefore, Weber B fractures which involve fractures of both the medial and lateral malleolus are best treated by surgical stabilization. Furthermore, Weber B fractures involving only the lateral malleolus, but which present with lateral subluxation of the talus, are definitely unstable and require fixation.

In contrast, controversy exists between surgeons regarding the optimal means of treating an undisplaced but potentially unstable fibula fracture. Many surgeons recommend routine operative fixation, while others recommend routine non-operative treatment.A clear rationale exists for both types of treatment.

The most important factor in treatment includes maintaining the reduction of the talus within the ankle mortise. Even 1 mm of displacement or lateral shift of the talus will affect ankle joint loading and lead to dysfunction and potentially arthritis. Other issues include the potential benefits of earlier mobilization and rehabilitation.

Inclusion criteria

• Skeletally mature male or female < 65 years of age
• Unstable ankle on stress exam: medial clear space ³ 5 mm: no Mortise shift on static radiographs
• Unilateral Weber B fibular fractures
• Closed fracture
• Provision of informed consent -

Exclusion criteria

• Fractures not amenable to surgical treatment
• Pathologic fracture
• Associated injuries to the foot, ankle, tibia, or knee
• Associated medial malleolus fracture
• Surgical delay of >2 weeks from time of injury
• Previous fracture or retained hardware in the affected limb
• Associated neurovascular injury or deficit in the affected limb
• Systemic diseases including diabetes, multiple sclerosis, Parkinson's disease, and other disorders which might affect peripheral sensorimotor function -