Ankle and Pilon Fractures

Kevin L. Kirk, DO

Johnny Owens, MPT

Dr. Kirk or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of Horizon Pharma; and serves as a board member, owner, officer, or committee member of the American Orthopaedic Foot and Ankle Society. Dr. Owens or an immediate family member serves as a paid consultant to Delfi Medical Innovations.

Introduction

Ankle fractures involve the lateral malleolus of the fibula, or the medial or posterior malleolus of the tibia, either alone or in combination. These patterns are due to a rotational injury of the ankle. Fractures of the ankle are typically associated with lower-energy mechanisms, such as a twisting injury while descending from stairs or sports injury. Pilon fractures, on the other hand, result from an axial load and involve the disruption of the weight-bearing articular surface to varying degrees. Pilon fractures therefore carry a worse prognosis. Common mechanisms are falls from a height or motor vehicle crashes.

The ankle joint is a complex, three-bone joint. It consists of the tibial plafond, including the posterior malleolus articulating with the body of the talus, the medial malleolus, and the lateral malleolus. The joint is considered saddle-shaped, with a larger circumference of the talar dome circumference laterally than medially. The dome itself is wider anteriorly than posteriorly; as the ankle dorsiflexes, the fibula rotates externally through the tibiofibular syndesmosis to accommodate this widened anterior surface of the talar dome. The unique osseous anatomy of the talocrural joint, in which the talus is wider anteriorly than posteriorly, provides stability in dorsiflexion and relative mobility in plantarflexion. In standing, the relatively dorsiflexed ankle joint behaves like a true mortise, with stability conferred principally by articular contact. In the non–weight-bearing, plantarflexed position, ankle joint stability is mostly conferred from the ligamentous structures. It is this unique structure that can have implications for rehabilitation in that loss of dorsiflexion is much more common than loss of plantarflexion motion. Therefore, rehabilitation strategies should be developed to regain dorsiflexion motion as early as possible in the rehabilitation course.

Pilon fractures are intra-articular fractures of the distal end of tibia that involve a significant portion of the weight-bearing articular surface. Although the articular component will involve some combination of the medial, lateral, or posterior malleoli, the defining character of the tibial pilon fracture is the involvement of the superior weight-bearing articular area and the and metaphysis. The comminution of the articular surface, primary articular cartilage damage, and joint surface incongruity contribute to the generally worse outcome of these injuries compared to ankle fractures.

Specific knowledge of the mechanism of injury is an important aspect of the assessment of pilon fractures. The mechanisms of injury can either be high-energy, such as motor vehicle accidents, falls from heights, and industrial accidents, or low-energy torsional injuries with an axial load component, such as skiing (“boot-top fracture”; Figure 75.1). The fracture pattern is influenced by the axial compression that occurs from the talus being driven into the tibial plafond. In addition, the shearing or rotational component produces variable degrees of separation of the fracture fragments and instability. Rehabilitation of tibial pilon fractures is influenced by the greater involvement of the articular surface and metaphyseal involvement, in which weight-bearing progression may be more delayed and full range of motion (ROM) of the ankle more difficult to achieve.

Surgical Procedure: Ankle Fracture

Indications

Any fracture that disrupts the ankle mortise may require open reduction and internal fixation (ORIF) of either the lateral, medial, and/or the posterior malleolus. Instability is present when the talus shifts laterally or medially from its position under the tibia. Fracture of the lateral malleolus and disruption of the deltoid ligament is a common unstable ankle fracture treated surgically. When two or more malleoli are fractured, the ankle is by definition unstable and usually also best treated with surgery as well. In addition, the syndesmosis—the joint between the distal tibia and fibula—may be disrupted, requiring fixation with either screws or suture button fixation.
The goal is to restore accurate joint alignment to limit the risk of arthritis, especially in the younger active patient.

Figure 75.1 A, Ankle fracture radiograph. Note fracture of the medial and lateral malleolus. B, Pilon fracture radiograph. Note that, in addition to the fracture of the medial and lateral malleolus, the plafond or weight-bearing area is fractured.

Contraindications

While the decision for operative versus nonoperative treatment is frequently clear, for a group of patients such as diabetics and low-demand elderly, the treatment decision is more difficult. In these patients, closed reduction may be acceptable when considering the acute risk of anesthesia and soft-tissue breakdown compared to the late risk of arthritis. Specific contraindications to surgery include severe soft-tissue compromise, active infection, and medical instability that would prevent safe surgery.

Relevant Surgical Anatomy

The approach to the lateral or medial malleolus is generally straightforward; however, the superficial peroneal nerve on the lateral side and the saphenous nerve on the medial side can be encountered during dissection. Identification of the nerves and avoidance of trauma to the nerves can prevent any unnecessary complications.

Technique

Since the medial and lateral malleoli are subcutaneous, the approach is directly over these structures. Laterally, the dissection pays attention to the peroneal tendons and the superficial peroneal nerve. Once identified and protected, the fracture is reduced and the plate is applied laterally or posterolaterally. Careful closure is performed to ensure healing. Medially, the dissection secures the saphenous nerve. The fracture is reduced, then fixed with either screws, plates, or, in some cases with comminution, wires and pins. Attention is paid to the posterior tibial tendon to avoid injury.

The posterior malleolus, depending on its size and displacement, may require fixation. It may be indirectly reduced and fixed percutaneously. Many surgeons prefer to perform a direct reduction from a posterolateral approach. A vertical incision is made laterally between the lateral malleolus and the Achilles tendon. The deeper fascia posterior to the peroneals is split, exposing the flexor hallucis muscle, which is elevated off the posterior tibia, exposing the posterior malleolus. The posterior malleolus is then reduced and fixed with either screws or a plate. Following fixation of the malleoli, the syndesmosis is evaluated and fixed with screws or suture to ensure a stable mortise. Syndesmotic screws may also be useful in patients with poor bone stock to optimize fibular fixation in the absence of syndesmotic injury.

Complications

Wound Healing and Infection

The subcutaneous nature of the malleoli can lead to wound healing problems and infection. Diabetics, smokers, and noncompliant patients not vigilant with elevation instructions following injury and surgery are at particular risk. Initial surgery may be delayed to resolve severe swelling and blisters. Any wound dehiscence or drainage warrants prompt notification of the surgeon, who may institute wound care, antibiotics, and even surgical débridement.

Stiffness

Loss of motion, especially dorsiflexion, can be problematic following ankle fracture. If independent ROM exercises and
stretching is not rapidly successful in restoring a functional ROM, early referral should be made to physical therapy. Rarely, a posterior, soft-tissue, capsular release, along with lengthening of the Achilles and other flexor tendons, may be indicated to improve severely restricted ankle dorsiflexion.

Hardware Prominence and Pain

Hardware prominence is fairly common in thin individuals following ankle fracture fixation due to the subcutaneous location of the hardware. This most commonly involves lateral fibular plates and screws. Symptomatic relief can usually be obtained with outpatient hardware removal after the fracture is adequately healed. Often, patients are encouraged to wait 1 year from the time of surgery before removing their hardware. Patients are permitted full weight bearing after hardware removal, but are cautioned against activities that could cause significant torsional force for 6 to 12 weeks following hardware removal.

Nerve Injury

The superficial peroneal and the saphenous nerves can be injured at the time of the event, during surgery, or postoperatively become entrapped in scar tissue. If symptomatic, desensitization and occasionally injections can ameliorate symptoms.

Complex Regional Pain Syndrome

An exaggerated response to injury of an extremity manifested by (1) intense or unduly prolonged pain, (2) vasomotor disturbances, (3) delayed functional recovery, and (4) various associated trophic changes. The exact pathophysiology is unknown. However, women are affected more than men, especially with the risk factor of smoking. Symptoms in the lower extremity are more refractory to intervention than those in the upper extremity. Early diagnosis and aggressive treatment with desensitization, edema control, ROM, pharmacologic treatment with gabapentinoids, and at times sympathetic nerve block can lead to successful outcomes.

Surgical Procedure: Tibial Pilon Fracture

Indications

Most surgeons agree that displaced tibial pilon fractures require accurate reduction of the articular surface, proper alignment between the articular segment with the metaphysis/diaphysis, and a stable construct to allow early motion. The ability to achieve these goals is directly related to the severity of the articular damage, displacement, and comminution of the metaphysis/ diaphysis, the quality of bone, and patient factors. Due to the high incidence of wound complications, most surgeons perform a two-stage approach in the management of these fractures, that is, initial temporary external fixation with or without internal fixation of the fibula followed by delayed internal fixation. In some cases, the interval may be 3 or more weeks in the event of severe soft-tissue compromise.

Procedure

Several approaches may be useful in treating these complex fractures. The specific approach depends on the fracture configuration, soft-tissue constraints, and surgeon preference. Standard approaches include anteromedial, direct anterior, anterolateral, and posterolateral.

The classic anteromedial approach provides ready access to the medial and anterior tibia. The anterior of the ankle is accessed by releasing the retinaculum and capsule working under the tibialis anterior, the anterior tibial artery, and the toe extensors. The anterolateral approach is made anterior to the fibula generally in line with the fourth ray. The extensor retinaculum is released and the peroneus tertius and toe extensors are elevated, exposing the joint and the fracture. The posterolateral approach is performed as described in the ankle section. These approaches may be used alone or in combination to allow adequate exposure for reduction and rigid fixation with plates and screws. Careful closure is performed to include the retinaculum and skin to optimize skin healing.

Complications

Wound Complications

Soft-tissue compromise can occur in both ankle and tibial pilon fractures. However, due to the higher-energy mechanisms of injury in pilon fractures and the wider dissection, the risk of wound complications and infection is higher. Due to these higher risks of wound breakdown, active motion of the ankle may be delayed for several weeks to ensure adequate healing of the soft tissues.

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