Approach to the posterolateral surface of the tibial shaft

The posterolateral approach is ideal for use in the midshaft and distal tibia. It is used for open plate fixation of the tibia on its posterior surface. This may be necessary when the anterior soft tissues are compromised.

The posterior surface of the tibia is relatively flat and therefore little contouring of the plate is necessary.

This approach is often also utilized for treatment of nonunions with posterolateral bone grafting. It allows access to both the tibia and fibula.

It is a more challenging approach requiring a thorough understanding of the surgical anatomy.

This approach is rarely used in the proximal tibia.

Approach to the posterolateral surface of the tibial shaft

The patient may be positioned either laterally or prone. Since the fibula lies more posteriorly than the tibia, a prone position greatly facilitates exposure, and is preferred.

A tourniquet helps to minimize venous bleeding, which may become significant. Place it high on the thigh, after the patient is positioned. Inflation is optional.

The triangular shape of the tibia

The lateral and posterior surfaces of the tibia are covered by muscle. The anteromedial surface has only a thin layer of subcutaneous tissue and skin. This surface provides less blood supply to the underlying bone.

Compartments

The lower leg has four compartments:

Anterior
Lateral
Deep posterior
Superficial posterior

The anterior compartment has three muscles, one main artery, and one nerve: the tibialis anterior, extensor hallucis longus, extensor digitorum longus, the anterior tibial artery, and the deep peroneal nerve.

The lateral compartment has two muscles and one nerve: the peroneus longus and brevis, and the superficial peroneal nerve.

The deep posterior compartment has three muscles, two arteries, and one nerve: the tibialis posterior, flexor hallucis longus and flexor digitorum longus, and the peroneal and posterior tibial arteries, as well as the tibial nerve.

The superficial posterior compartment has two muscles and one nerve: the gastrocnemius, the soleus, and the sural nerve.

The length of the incision varies, but it should begin over the lateral border of the gastrocnemius muscle and extend distally to a point that is midway between the Achilles tendon and the fibula.

Approach to the posterolateral surface of the tibial shaft - skin incision

The interval between the lateral and posterior compartments is usually easier to find distally. Proximal dissection then follows.

Approach to the posterolateral surface of the tibial shaft - the interval between the lateral and posterior compartments is usually easier to find distally.

The plane of the dissection is between the superficial posterior and lateral compartments. The fascia is incised, and the gastrocnemius and soleus are mobilized medially leaving the peroneal muscles laterally. In this way, the posterolateral aspect of the fibula is exposed.

Approach to the posterolateral surface of the tibial shaft - the plane of the dissection will be between the superficial posterior and lateral compartments.

Often there are crossing perforating branches of the peroneal vessels, which must be ligated.

Approach to the posterolateral surface of the tibial shaft - often there are crossing perforating branches of the peroneal vessels, which must be ligated.

The Flexor hallucis longus (FHL) arises from the posterior aspect of the fibula. This is mobilized posteromedially. Medial dissection is continued until the interosseus membrane is encountered.

Approach to the posterolateral surface of the tibial shaft - The Flexor hallucis longus (FHL) arises from the posterior aspect of the fibula. This is mobilized posteromedially.

Note: It is important to proceed with caution when mobilizing the deep posterior compartment. It is crucial that the entire compartment is mobilized from the fibula, interosseous membrane, and tibia.

Beginning outside the fracture zone, expose the posterior and medial surfaces of the fibula, and follow these to the interosseous membrane. Retract the deep posterior compartment contents from lateral to medial, to protect the neurovascular structures.

Approach to the posterolateral surface of the tibial shaft - one should proceed with caution when mobilizing the deep posterior compartment.

With the interosseous membrane identified, mobilize the remainder of the deep posterior compartment medially until the posterior aspect of the tibia is encountered. Extend the exposure proximally beyond the fracture as far as necessary for plate fixation.

Be aware of the common peroneal nerve crossing the fibular neck very proximally.

Approach to the posterolateral surface of the tibial shaft - mobilize the remainder of the deep posterior compartment medially until the posterior aspect of the tibia is encountered.

At the conclusion of the dissection the surgeon should have access to the posterior aspects of both the tibia and the fibula shafts.

Approach to the posterolateral surface of the tibial shaft - at the conclusion of the dissection the surgeon should have access to the posterior aspects of both the tibia and the fibula.

Pearl: The posterior dissection is often difficult in the zone of injury, so it is often best to begin the dissection outside of this zone, where the anatomy is more normal.

A drain can be placed in the deep zone of the dissection to prevent postoperative hematoma formation. While the fascia may be closed between the superficial posterior and lateral compartments, swelling and compartment syndrome are definite risks.

If there is any concern about a developing compartment syndrome, the fascia should be left open and only the skin and subcutaneous layers closed, if deemed to be safe. If compartment syndrome is anticipated to develop postoperatively, skin and subcutaneous tissue should not be closed. Temporary wound coverage techniques need to be employed until swelling resolves and definitive wound closure can occur safely.