DIFFICULT ANKLE

be required in the long term to prevent progression of degenerative disease in the joint.

Earlier suspicion and investigation

for talar dome lesions will reduce the severity of these injuries and the longer term morbidity.

3. AVULSION FRACTURE OF THE BASE OF THE 5th METATARSAL This lesion can occur on its own or in combination with a lateral ligament sprain. It results from the avulsion of the peroneus brevis tendon from its attach- ment (Fig.3) and may require immobilisa- tion for 1-2 weeks before gradual mobili- sation. It is important to distinguish this fracture from that of a Jones fracture which is a fracture of the proximal diaph- ysis and has a strong tendency to non- union.

4. FRACTURE OF THE LATERAL TALAR PROCESS Cause: This previously uncommon frac- ture has been increasingly seen since the advent of snow boarding.

It tends to

occur when soft shell boots are used and may occur from forced dorsiflexion and inversion injury when landing from a jump. Estimates suggest that it may be responsible for up to 15% of snow board- ing ankle injuries.

Presentation: The lateral talar process (Fig.2b) is the prominence on the lateral body of the talus. It has an articular sur- face with both the fibular and also inferi- orly with the calcaneus.

The tenderness

and bruising occurs over the lateral aspect of the ankle and may be mistaken for lig- amentous injury.

Figure 3: Lateral view of ankle (superficial) ©1999 Primal Pictures Ltd

Tendons of peroneus longus and brevis

Management: The type I lesion is a chip fracture of the articular process of the talus and may be seen on a lateral view or mortise view of the ankle but it can be

difficult to visualise.

This lesion is man-

aged with a short-leg partial weight bear- ing cast for six weeks. The type II lesion produces a single large fragment extend- ing from the talo-fibular to subtalar joint. This lesion requires open reduction and internal fixation to maintain the congru- ence of the articular surfaces.

The type

III lesion is a comminuted fracture involving the entire lateral process and these lesions are usually excised to pre- vent degeneration in the subtalar joint.

Peroneal retinaculum

Investigation: All lesions are difficult to view on plain films and are better seen on CT, MRI or lateral tomograms. There should be a high index of suspicion for this lesion in persistent pain in a snow boarder.

Base of 5th metatarsal Attachment of peroneus brevis tendon 30 SportEX

5. OTHER FRACTURES Other fractures can occur following inver- sion injury and include the anterior process of the calcaneus, the tibial pla-