Stable fractures of the ankle can be successfully treated non-operatively by a below-knee plaster cast. In some centres, patients with this injury are routinely administered low-molecular-weight heparin, to reduce the risk of deep-vein thrombosis (DVT). We have assessed the incidence of DVT in 100 patients in the absence of any thromboprophylaxis. A colour Doppler duplex ultrasound scan was done at the time of the removal of the cast.

Five patients did develop DVT, though none had clinical signs suggestive of it. One case involved the femoral and another the popliteal vein. No patient developed pulmonary embolism. As the incidence of DVT after ankle fractures is low, we do not recommend routine thromboprophylaxis.

Forty-seven patients over the age of 55 years with a displaced fracture of the ankle were entered into a prospective, randomised study in order to compare open reduction and internal fixation with closed treatment in a plaster cast; 36 were reviewed after a mean of 27 months. The outcome was assessed clinically, radiologically and functionally using the Olerud score.

The results showed that anatomical reduction was significantly less reliable (p = 0.03) and loss of reduction significantly more common (p = 0.001) in the group with closed treatment. Those managed by open reduction and internal fixation had a significantly higher functional outcome score (p = 0.03) and a significantly better range of movement of the ankle (p = 0.044) at review.