Tibial Pilon Fractures

Pilon is a French term used to describe a fracture of the distal tibia usually characterized by high-energy traits, including dissociation of the articular surface from the tibia shaft.

• Destot coined the term pilon, as he thought that the distal tibial metaphysis resembled a pharmacist’s pestle.

Plafond is also a French term, described by Bonin, referring to the distal tibial articular surface as the roof (ceiling) of the ankle joint.

At the level of the ankle, the distal tibia is intimately associated with the fibula through strong ligamentous attachments.

• The attachments are as follows:

  • –

    Anterior inferior tibiofibular ligament

  • –

    Posterior inferior tibiofibular ligament

  • –

    Interosseous ligament

  • –

    Inferior transverse ligament

The articular surface of the distal tibia is concave in both the coronal as well as the sagittal plane.

The talus has the opposite geometry of the tibial plafond and therefore serves as a perfect template for assessing articular reduction of the distal tibia.

The concave tibial plafond provides ~ 40% more posterior than anterior coverage.

The pilon fracture usually has an anterolateral (Chaput) fragment and a posterolateral (Volkmann) fragment, which usually remain attached to the distal fibula segment by the anterior and posterior tibiofibular ligaments.

In the vast majority of pilon fractures, the fracture lines propagate from the fibular incisura laterally in the shape of a Y to exit anterior and posterior to the medial malleolus.

Comminution, which frequently occurs with high-energy pilon fractures, is most typically located in the anterolateral and central regions of the plafond.

There simply is not a lot of soft tissue around the distal tibia, as compared to more proximal parts of the leg.

• There is no muscle tissue to "cushion" or protect the bone if skin is injured.

The tendons of the anterior compartment, the dorsalis pedis artery, and the superficial and deep peroneal nerves can be encountered with anterior exposures at the level of the ankle joint.

The tendinous and neurovascular structures are covered proximally by the investing fascia of the anterior compartment and distally by the extensor retinaculum.

The superficial peroneal and saphenous nerves are superficial to the fascia.

• The superficial peroneal nerve pierces the fascia of the lateral compartment ~ 12 cm proximal to the ankle joint en route to provide sensation to a majority of the dorsum of the foot.

Anterolateral exposures for pilon fractures risk injury to the superficial peroneal nerve.

The dorsalis pedis and deep peroneal nerve are at risk with an anterior exposure.

• They run together in the pericapsular fat between the extensory digitorum and extensor hallucis longus tendons.

The tibial pilon fracture is a rare yet devastating injury.

Despite the best treatment, patients sustaining high-energy pilon fractures generally do not return to their previous state of general health or function.

• After recovery from pilon fractures, many patients continue to have debilitating pain and ankle stiffness (Babis et al 1997, Sands et al 1998, Pollak et al 2003).

Fortunately, pilon fractures compose a minority of tibia or lower extremity fractures, occurring in ~ 7% and 1% of all cases, respectively.

Pilon fractures can occur from both low- and high-energy mechanisms.

• Low-energy fractures typically occur due to rotational forces imparted to the distal tibia.

• High-energy fractures are generally due to axial force that drives the talus into the tibial plafond, causing an “implosion” of the articular surface.

In the most severe plafond fracture patterns, the articular segment is fractured into numerous pieces with certain segments driven proximally into the metaphysis, creating marked joint incongruity and associated metaphyseal defects.

An associated fibula fracture is often present in pilon fractures.

The most common fracture pattern occurs with the ankle in dorsiflexion (i.e., the foot on the brake pedal during a motor vehicle accident).

• When the ankle is dorsiflexed at the time of injury, pilon fracture patterns involve the anterior articular surface of the tibial plafond.

Central articular (implosion) injury is the result of an axial load on the foot in neutral position.

A severely traumatized soft tissue envelope accompanies the higher energy pilon fractures.

• Although many pilon fractures are open injuries, closed fractures have significant soft tissue compromise as well.

Initial management of pilon fractures depends as much on the soft tissue as the bony injury.

• Understanding the soft tissue injury accompanying pilon fractures is of utmost importance for providing optimal treatment while minimizing complications.