What are the indications for the posterolateral approach to the ankle?

This approach is generally used for pilon fractures and ankle fracture surgery, espe- cially to access the posterior malleolus fracture fragment where there is a large, dis- placed posterior malleolus fracture that cannot be reduced by closed means or held reliably from anterior to posterior. A long oblique fracture which may tend to dis- place due to shear forces may benefit from a posterior malleolus buttress plate. The fibula can often be plated through the same incision if required.

2. What is the internervous plane utilised by this approach?

This internervous plane is between the peroneal tendons laterally (superficial pero- neal nerve) and the flexor hallucis longus (FHL) medially (tibial nerve).

3. How would you position the patient?

The patient can be placed prone or lateral for this approach. My preference is to place the patient in the lateral position, injured side uppermost.

4. Where would you base your incisions and what structures must be avoided?

I would be vigilant to ensure to leave an adequate skin bridge of 7 centimetres or more between the two incisions to reduce the risk of tissue necrosis affecting the skin bridge.

5. Talk me through the dissection.

I would use blunt dissection in the superficial fat. The sural nerve runs with the short saphenous vein at this level and should be preserved where possible and protected to prevent a painful neuroma. A plane is then developed between the peroneal tendons laterally and the Achilles tendon medially in order to reveal the FHL muscle belly, which is low-lying and often extends to the level of the ankle joint, hence the term ‘beef to the heel’ used to describe it.

To access the posterior malleolus, a longitudinal incision is made through the lateral fibres of the FHL as they arise from the fibula. The FHL is then retracted medially to reveal the periosteum overlying the posterior malleolus.

To access the fibula through this approach, the peroneal tendons are retracted medially, giving excellent access to the posterior distal fibula.

6. How is the sural nerve formed and what does it supply?

The sural nerve is formed by branches of the tibial nerve (medial sural cutaneous nerve) and the common peroneal nerve (lateral sural cutaneous nerve) and crosses from medial to lateral, crossing the lateral border of the Achilles tendon approxi- mately 10 cm proximal to its insertion. The sural nerve is purely sensory: It supplies the lateral aspect of the foot.

7. What are the dangers of this approach?

Short saphenous vein and sural nerve as above.