Posterolateral Approach to Ankle Joint

The posterolateral approach to ankle joint is used to treat conditions of the posterior aspect of the distal tibia and ankle joint. It is well suited for open reduction and internal fixation of posterior malleolar fractures.

The posterolateral approach to ankle joint other uses include the following:

1. Excision of sequestra.
2. Removal of benign tumors.
3. Arthrodesis of the posterior facet of the subtalar joint.
4. Posterior capsulotomy and syndesmotomy of the ankle.
5. Elongation of tendons.

Because the patient is prone, however, it is not the approach of choice if the fibula and medial malleolus have to be fixed at the same time. In such cases, it is better to use either a posteromedial approach or a lateral approach to the fibula, and to approach the posterolateral corner of the tibia through the site of the fractured fibula.
Neither of these approaches provides such good visualization of the bone as does the posterolateral approach to the ankle, but both allow other surgical procedures to be carried out without changing the position of the patient on the table halfway through the operation.

Position of the Patient

• Place the patient prone on the operating table.
• A sandbag should be placed under the ankle so that it can be extended during the operation.

Landmarks and Incision

• Landmarks:
  1. Lateral malleolus.
  2. Achilles tendon.
• Incision:
  • Make a 10-cm longitudinal incision halfway between the posterior border of the lateral malleolus and the
    lateral border of the Achilles tendon.
  • Begin the incision at the level of the tip of the fibula and extend it proximally.

Internervous plane for posterolateral approach to ankle joint

The internervous plane for The posterolateral approach to ankle joint lies between:

• The peroneus brevis muscle: which is supplied by the superficial peroneal nerve.
• The flexor hallucis longus muscle: which is supplied by the tibial nerve.

Superficial dissection

• Mobilize the skin flaps, the short saphenous vein and sural nerves run just behind the lateral malleolus.
• Incise the deep fascia of the leg in line with the skin incision, and identify the two peroneal tendons as they pass down the leg and around the back of the lateral malleolus.
  • The tendon of the peroneus brevis muscle is anterior to that of the peroneus longus muscle at the level of the ankle joint and, therefore, is closer to the lateral malleolus.
• Incise the peroneal retinaculum to release the tendons, and retract the muscles laterally and anteriorly to expose the flexor hallucis longus muscle.

Deep dissection

• Make a longitudinal incision through the lateral fibers of the flexor hallucis longus muscle as they arise from the fibula.
• Retract the flexor hallucis longus medially to reveal the periosteum over the posterior aspect of the tibia.
• If the distal tibia must be reached, develop an epi-periosteal plane between the periosteum covering the tibia and the overlying soft tissues.
• To enter the ankle joint, follow the posterior aspect of the tibia down to the posterior ankle joint capsule and incise it transversely.

Approach Extension

• To extend the posterolateral approach to ankle joint proximally, extend the skin incision superiorly and identify the plane between the lateral head of the gastrocnemius muscle and the peroneus muscles.
• Develop this plane down to the soleus muscle; retract it medially with the gastrocnemius. Next, reflect the flexor hallucis longus muscle medially, detaching it from its origin on the fibula.
• Continue the dissection medially across the interosseous membrane to the posterior aspect of the tibia.

Dangers

The structures at risk during the posterolateral approach to ankle joint include:

• The Short saphenous vein.
• The sural nerve.

They both run close together. They should be preserved as a unit, largely to prevent the formation of a painful neuroma.

References

• Surgical Exposures in Orthopaedics book – 4th Edition
• Campbel’s Operative Orthopaedics book 12th
• Ankle Posterolateral Approach – Orthobullets