Ankle Fractures

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CHAPTER 10 Ankle Fractures

Ankle fractures are common, and although joint stability can be regained by adequate reduction and internal fixation of the fracture, some patients have disabling, persistent pain even after joint congruity is completely restored.¹^,² Persistent pain may be associated with exercise or change in the weather, and there may be radiographic evidence of osteoarthritic changes. These features suggest that an articular cartilage lesion or another radiographically nondetectable lesion might have occurred at the time of injury and may be the cause of the pain.

Ankle injuries result from abnormal motion of the talus within the ankle mortise. Fractures of the malleoli can result from impact of the talus on the malleoli caused by rotational or translational forces. Fractures can also occur in tension, and the malleoli can be avulsed because of pull exerted by the intact collateral ligaments to the talus.³^,⁴

Ankle fracture treatment is still based on classification criteria that were created in a time when the ankle was thought to be a simple hinge and only plain radiographs were available to assist diagnosis. This may explain why final results do not always correlate with the extent of bone damage and the reduction and stability achieved. It also suggests the need for specific studies to determine how and to what extent accompanying injuries are predictive factors for outcome in ankle fracture.

Hintermann and coworkers prospectively evaluated the arthroscopic findings in 288 consecutive patients with acute ankle fracture (148 male and 140 female patients; mean age, 45.6 years).⁵ They found that, independent of fracture type, cartilage lesions were most frequently present on the talus and to a lesser extent on the tibia, fibula, and medial malleolus. The frequency and severity of cartilage lesions increased from type B to type C fractures, and there was an increase observed from subgroup 1 to subgroup 3 in both type B and type C fractures. These findings support the belief that the severity of injury directly depends on the height of the fibula fracture. The fact that there was an unexpectedly high incidence of cartilage lesions in all fracture types may explain the observation from daily practice that the final results do not always correlate with the reduction and stability achieved. It seems that the fate of the fractured ankle (i.e., prognosis) may be determined to a significant extent during the accident itself, when the cartilage and other intra-articular and periarticular structures are injured.

Cartilage lesions apparently occur when the talus is rotated or translated in the loaded ankle mortise until the fracture occurs. This is especially true for type C fractures, and it is true to a lesser extent for type B fractures as long as the underlying mechanism is a pronation or rotation movement. Supination trauma, as typically seen in type A fractures, may critically stress the medial half of the joint, but the load forces may not be as high as in pronation or rotation trauma. Taga and colleaues ⁶ found cartilage lesions in the medial joint in 89% of 9 patients evaluated after an acute ankle sprain and in 95% of 22 patients with chronic ankle sprain. They found more cartilage lesions on the distal tibia than on the medial talus. They concluded that these injuries were mainly caused by local stress concentration. They found no correlation between the severity of the cartilage lesion and the degree of instability. This may support the belief that cartilage lesions occur to a significant extent at the time of the acute injury.

A higher incidence of cartilage lesions occurs in female patients than in male patients, and this can be explained by several factors. First, the cartilage may be less resistant to mechanical stress in females.¹ Second, the cartilage may have become more vulnerable with increasing age (because the age of the female patients was significantly higher).⁵ Third, overall muscular and bony strength are lower in females, so that fracture probably occurs during an earlier phase of the injury, and with a higher incidence, exposing the articular surfaces to a higher risk of possible damage. This may be especially true for elderly patients.

Arthroscopy performed directly after ankle fracture can be used to visualize intra-articular lesions that cannot be detected on plain radiographs.⁵^,⁷ Cartilage lesions were found in 79.2% to 90.0% of patients examined arthroscopically.⁵^,⁸ The ligaments could not be identified by arthroscopy in all cases, and there were significant differences among the four ligaments; overall, more injuries to the ligaments were found than expected.⁵ Although its role has not been established in the acute treatment of ankle fractures,⁹ arthroscopy has proved to be valuable for providing detailed knowledge of the fractured ankle.⁵^,¹⁰ It has also been helpful in the treatment of symptomatic osteophytes after ankle fracture.²

The aim of this chapter is to give an overview of my own technique and experience in arthroscopic evaluation of the acutely fractured ankle. In particular, an attempt is made to define the role of arthroscopy when treating ankle fractures.

NORMAL AND PATHOLOGIC ANATOMY

The ankle joint consists of three bones that form the malleolar mortise. They are connected by a complex ligamentous apparatus to provide stability. However, a unique feature of the ankle joint is its high concentration of articular surfaces. Injuries can affect the ligaments alone or both ligamentous and bony structures. Typically, the result is an unstable ankle joint, particularly in cases involving bony structures (e.g., ankle fractures).

PATIENT EVALUATION

History and Physical Examination

Acute ankle fractures result from severe trauma, such as traumatic inversion, eversion, or rotation. In most instances, a combination of different movements leads to a typical injury pattern. The history sometimes is helpful to elucidate the exact mechanism of injury, but frequently the patient does not recall the exact combination of inversion, eversion, and rotational forces that occurred at the time of injury. Physical examination consistently reveals swelling and tenderness to palpation over the fractured bone. Ecchymosis usually occurs over the first 24 hours. It is important to remove any splinting material that may have been applied at the time of injury, in order to assess for deformity of the ankle that accompanies a fracture dislocation. The skin must be carefully assessed for compromise, and the presence of pulses in the foot should be documented, especially in cases of fracture dislocation. On rare occasions, open fractures may occur, even if the bony deformity is mild.

Diagnostic Imaging

Standard radiographs of the ankle are the main step in imaging for diagnosis of an acute ankle fracture. In more complex cases, a computed tomography scan may be used to better visualize the injury pattern, in particular in regard to damage to the articular surfaces.

MANAGEMENT

Indications and Contraindications

Theoretically, every fractured ankle can be viewed by arthroscopy before open reduction and internal fixation (ORIF). However, arthroscopy may not be helpful in all fractured ankles. I recommend considering arthroscopic evaluation for cases in which the proposed fracture mechanism does not explain the extent of the lesion or the imaging findings do not explain the overall injury. For instance, if an intermediate fragment is suspected in the case of a posterior fracture, arthroscopy may be helpful in confirming the diagnosis and deciding whether an additional posteromedial approach should be performed to reposition and fix the posterior fragment properly. Likewise, if an injury to the deltoid ligament is present or suspected, arthroscopy can help determine whether reconstruction is advised. In some cases, arthroscopy may allow the surgeon to recognize an interposed deltoid ligament between talus and medial malleolus after closed reduction of the fracture.

Arthroscopy is generally contraindicated if there is significant damage to the skin or a poor soft tissue mantle is present, because it might provoke further injury to the soft tissues due to swelling caused by filling of the ankle joint.

Conservative or Operative Management

It is generally accepted that ORIF is the best treatment for unstable or dislocated ankle fractures.¹¹^–¹⁵ Few investigators suggest that perfect reduction is required to achieve good long-term results. Bauer and associates studied 143 patients 30 years after they sustained an ankle fracture that was treated by closed methods and found that 82% were free of arthritis and 83% were free of symptoms.¹¹ In contrast, in a series by Beris and colleagues of 23 patients who had an ankle fracture with poor reduction, 78.3% developed osteoarthritis.¹⁶ Accordingly, I limit nonoperative treatment to older or polymorbid patients with ankle fractures without dislocation.

Arthroscopic Technique

The patient is placed supine on the operating table. The knee is flexed to about 90 degrees using a knee holder; this allows the leg to assume a hanging position with the foot and ankle touching the table (Fig. 10-1). No ankle distraction device is used. To avoid iatrogenic lesions of the articular cartilage and soft tissue, the joint is first inflated with saline, and portals are created by blunt dissection. A 4.5-mm, 30-degree arthroscope is introduced into the ankle joint through a standard central anterior portal (Fig. 10-2). The liquid is evacuated, and the cavity is filled with saline. If necessary, accessory anteromedial or anterolateral portals, or both, are also used for insertion of instruments. Systematic arthroscopic examination, as described by Ferkel and Orwin,¹ is performed to visualize the internal structures.

FIGURE 10-1 The knee is flexed over a knee holder so that the foot is in a hanging position. This allows free investigation of the ankle joint without the use of a distraction device.

FIGURE 10-2 A central anterior portal is used. Landmarks are the lateral border of the anterior tibial tendon and the tibiotalar joint line.

Articular cartilage lesions are graded according to the depth of the lesion, as assessed by inspection and probing:

Grade 1: superficial lesion

Grade 2: fissuring or degeneration of less than one half of the thickness of the articular cartilage (Fig. 10-3)

Grade 3: fasciculation or degeneration of greater than one half of the thickness of the articular cartilage (Fig. 10-4)

Grade 4: erosion of the cartilage down to the subchondral bone (Fig. 10-5)

FIGURE 10-3 Grade 2 lesion of cartilage.

FIGURE 10-4 Grade 3 lesion of cartilage.

FIGURE 10-5 Grade 4 lesion of cartilage.

The anterior talofibular ligament (Fig. 10-6), calcaneofibular ligament, deltoid ligament (Fig. 10-7), and anterior (Fig. 10-8) and posterior (Fig. 10-9) tibiofibular ligaments (syndesmosis) are assessed by inspection and probing. Ligament injuries are graded according to the severity of the fiber tear and the degree of instability present: A partial lesion involves a tear of less than one half of the ligament without complete instability, whereas a complete lesion implies a tear of the complete ligament or bony avulsion of the ligament with instability.

FIGURE 10-6 Avulsion of the anterior talofibular ligament together with the periosteum of external aspect of the fibula.

FIGURE 10-7 Deltoid ligament injury. A, There is complete rupture of anterior superficial bundles, but the deep tibiotalar bundles are intact. B, Interposition of ruptured anterior deltoid ligament between the medial malleolus and the talus. The medial joint space is markedly widened. C, Avulsion of the whole deltoid ligament from the medial malleolus.

FIGURE 10-8 Distal avulsion of the anterior tibiotalar ligament (syndesmosis).

FIGURE 10-9 Rupture of the posterior tibiotalar ligament (syndesmosis). A, The fibula is subluxated in the anterior direction. B, Closer inspection shows the rupture of the posterior syndesmotic ligament.

Arthroscopy is also used to visualize the fracture pattern (Fig. 10-10) and to detect unexpected injuries to articular surfaces, such as impression (Fig. 10-11).

FIGURE 10-10 Fractures of tibial plafond. A, A third fragment is seen posteriorly between the fracture of medial malleolus and the tibial plafond. B, A posterior tibial fragment (i.e., Volkman fragment) is minimally displaced.

FIGURE 10-11 Impression fracture of the anteromedial tibial plafond. A, Impression fracture with preserved articular surface. B, Impression fracture with interrupted articular surface and extended cartilage lesion.

Figure 10-12 shows a case in which arthroscopy was beneficial for understanding of the injury pattern, removal of a loose fragment, and reduction of the deltoid ligament that was interposed between the medial malleolus and the talus.