Rockwood Adults CH64

64

Ankle Fractures Tim White and Kate Bugler

INTRODUCTION TO ANKLE FRACTURES

INTRODUCTION TO ANKLE FRACTURES  2822

PATHOANATOMY, APPLIED ANATOMY, AND BIOMECHANICS RELATING TO ANKLE FRACTURES  2823

Ankle fractures represent 10% of all fractures with an incidence of around 137/10 5 population per year, 32,76 making these the sec- ond most common lower limb fractures after hip fractures. 75 The mean age at injury is 45 years, 76 significantly older than that of patients sustaining isolated ankle sprains. 405 Both injuries have a bimodal distribution, with peak incidences of ankle injuries in younger men and older women and a 50-year gap between peaks. 76 These are typically low-energy injuries with the major- ity occurring due to simple falls or sport. 76,81 Even open ankle fractures are predominantly low-energy injuries caused by sim- ple falls with the highest incidence in elderly women. 51 The epidemiology of the specific fracture patterns does how- ever vary. Patients with an AO type C fracture more commonly sustain their injury because of a fall from a height or a motor vehicle accident than patients with AO type A or B fractures, in which the most common cause is a simple fall. 76 Evaluation of only bimalleolar and trimalleolar ankle fractures reveals that these fractures do not have a bimodal distribution but instead a type E distribution with a peak only in elderly women. 75 The already high incidence of ankle fractures is increasing sharply in line with the aging demographic of most Western populations. Kannus et al. 179 reported an increase of 319% in the overall annual number of low-energy ankle fractures in elderly patients admitted to hospital over the three decades between 1970 and 2000. From this data they predicted that the number of low-energy ankle fractures could be expected to triple by 2030. They forecast a higher rate of increase in females (Fig. 64-1). The epidemiology appears to be varying with time: Between 1950 and 1980 an increase in incidence among younger males and elderly females was seen, 32 however more recently the incidence among younger men has appeared to remain static while the increase in elderly women has continued. 196,381 The mechanism of injury has also changed with a reduction in frac- tures occurring because of severe trauma between 1950 and 1980 and a concomitant increase in the proportion of fractures caused by sporting activity in men. 32

SURGICAL APPROACHES FOR ANKLE FRACTURES  2827 Medial Approach  2827 Posteromedial Approach  2827 Lateral Approach  2827 Posterolateral Approach  2827 ASSESSMENT OF ANKLE FRACTURES  2827 Classification of Ankle Fractures  2827 Clinical Assessment of Ankle Fractures  2837 Imaging and Other Diagnostic Studies for Ankle Fractures  2838 TREATMENT OPTIONS FOR ANKLE FRACTURES  2840 Evidence-Based Management of Ankle Fractures  2841 Operative Treatment of Ankle Fractures  2851

AUTHOR’S PREFERRED TREATMENT OF ANKLE FRACTURES  2863

OUTCOMES OF ANKLE FRACTURES  2868

MANAGEMENT OF ADVERSE OUTCOMES AND UNEXPECTED COMPLICATIONS IN ANKLE FRACTURES  2868

2822

2823

CHAPTER 64 • Ankle Fractures

consisting of the tibial plafond (ceiling) superiorly, and the medial malleolus medially. A dorsal projection of the tibia, the posterior malleolus, serves to enlarge this confluent area. The lateral articulation of the talus is with the distal fibula. Each of these articular surfaces shares in load distribution during weight bearing, with the fibula, for example, taking 1/6th of the load. 370 The medial malleolus is both shorter and more anterior, and thus the axis of the joint is in 15 degrees of external rota- tion. The tibial and fibular articular surfaces together comprise the mortise in which the talus sits (Fig. 64-2). The relationship between the tibia and fibula centers on the syndesmosis where the fibula lies in the incisura of the lateral aspect of the tibia, and is stabilized by the anterior-inferior tibiofibular ligament (AITFL), the posterior inferior tibiofibu- lar ligament (PITFL), and the interosseous ligament which is confluent with the interosseous membrane above (Fig. 64-3). The AITFL arises from a prominence of the anterolateral tibia known as the tubercle of Chaput (which may be avulsed, typi- cally in children’s ankle injuries), and inserts onto an equivalent prominence on the fibula: The tubercle of Wagstaffe. The PITFL arises from Volkmann’s tubercle of the posterior malleolus. It is extremely strong and in trimalleolar fractures the fragment usu- ally remains solidly attached to the fibula via this ligament. This relationship can be exploited surgically: Reduction of the distal fibula usually assists in reduction of the posterior malleolus, and conversely stabilization of the posterior malleolus will often restore stability to a fractured fibula. 253 The talus itself is remarkable for three reasons. Its surface is 70% covered in articular cartilage, it has no direct ligamentous attachments for muscle action and it has a tenuous retrograde vascular supply. The body of the talus is geometrically com- plex and describes a frustum, a cone with its apex removed, lying transversely in the mortise, being broader anteriorly and narrower posteriorly. This complex shape prevents the medial and lateral facets of the talus, and their relationships with their respective malleoli, from being seen on any single radiographic projection and this can result in considerable uncertainty when attempting to measure joint spaces unless all three views are obtained (see below). As a result of its frustral shape, the talus is compressed within the mortise of the ankle in dorsiflexion (the position of heel strike), causing the fibula to rotate externally, and is most stable in this position. In plantarflexion (at toe off) the talus is held less rigidly, allowing physiologic external rota- tion and inversion. 248 Osseous stability of the ankle increases with axial loading, when the congruency of the articular sur- faces provides very substantial stability even after division of all ligamentous restraints. 356 The superior surface of the talus (the talar dome), conforms closely to the plafond of the tibia, and the contact area between the two surfaces decreases markedly with displacement of the talus. Ramsey and Hamilton’s 315 famous study reported a decrease in contact area of 42% after just 1 mm of lateral talar displacement, an effect confirmed by other authors. 221,261 Although this study has been criticized, 402 and the precise rela- tionship between displacement, contact area, and contact pres- sure remain contentious, 80,186,379 it is widely accepted that loss of congruence of the mortise leads to altered biomechanical loading and is principally responsible for the poor outcomes

400

WOMEN 80-

350

70–78 60–69

300

250

200

INCIDENCE

150

100

50

0

1970 1980 1990 2000 YEAR

2010 2020 2030

Figure 64-1.  The changing epidemiology of ankle fractures. Data from Kannus et al. 179

Although ankle fractures are not associated with systemic low bone mineral density per se, 146,354 the microarchitecture of the trabecular bone in the distal tibia of elderly patients with ankle fractures is abnormal and depleted, and bone stiffness is reduced, compared with uninjured controls, 354 suggesting that these injuries should be considered to be true osteoporotic fractures. Specific risk factors for sustaining ankle fractures have been investigated. Hasselman et al. 146 undertook a prospective study of 9,704 women over the age of 65 and found that ankle frac- tures were more common in the obese and those with a history of multiple falls. Further evidence for obesity as a risk factor comes from the international GLOW study of 60,393 women. They found that obese women over the age of 55 years were significantly more likely to sustain an ankle fracture than non- obese women. 69 Moreover, Margolis et al. 235 found that patients with a greater percentage increase in weight since the age of 25 were also significantly more likely to sustain an ankle frac- ture. Obesity also predisposes to more severe injury. Spaine and Bollen 352 found that patients with an unstable ankle fracture were far more likely to be obese (29%) than patients with stable ankle fractures (4%). Alcohol use also appears to be a risk factor and Jensen et al. 170 reported that 29% of patients in their series were found to have consumed alcohol in the 4 hours preceding fracture.

PATHOANATOMY, APPLIED ANATOMY, AND BIOMECHANICS RELATING TO ANKLE FRACTURES

The surgical anatomy of the ankle joint has been well described in detail elsewhere. 159 The joint functions as a mortise with the body of the talus articulating with a confluent area of the tibia

2824

SECTION FOUR • Lower Extremity

Tibial plafond

Anterior

Medial malleolus

Fibula

B

Posterior

Interosseous membrane

Trochlea

Body

Fibula

Tibia

Neck

Head

C

Talus

A

Figure 64-2.  Bony anatomy of the ankle. Mortise view ( A ) inferosuperior view of the tibiofibular side of the joint ( B ), and superoinferior view of the talus ( C ). The ankle joint is a three-bone joint with a larger talar articular surface than matching tibiofibular articular surface. The lateral circumference of the talar dome is larger than the medial circumference. The dome is wider anteriorly than posteriorly. The syndesmotic ligaments allow widening of the joint with dorsiflexion of the ankle, into a stable, close-packed position.

IOL

PITFL

AITFL

ITL

AITFL

PITFL

Anterior

Lateral

Posterior

AITFL

Figure 64-3.  Three views of the tibiofibular syndesmotic ligaments. Anteriorly, the AITFL spans from the anterior tubercle and anterolateral surface of the tibia to the anterior fibula. Posteriorly, the tibiofibular lig- ament has two components: The superficial PITFL, which is attached from the fibula across to the posterior tibia, and the thick, strong ITL, which constitutes the posterior labrum of the ankle. Between the anterior and PITFLs resides the stout interosseous ligament (IOL).

2825

CHAPTER 64 • Ankle Fractures

observed in patients with residual displacement of the talus after ankle fracture. The stability of the ankle is enhanced by its capsule and ligaments. Medially, the deltoid (medial collateral) ligament has two components. The superficial deltoid ligament arises from the anterior colliculus of the malleolus and extends in a broad fan shape to insert into the talus, navicular, and the sus- tentaculum of the calcaneus. This insertion is continuous with the tendon sheaths of the tibialis posterior and flexor hallucis longus tendons. The deep deltoid ligament is intra-articular and extends from the posterior colliculus (and intercollicu- lar groove) of the malleolus to the dome of the talus. It is the deep component that is thought to be important in restrain- ing the talus against lateral displacement and rotation, and it is the focus of much interest and research. 294 The anatomy of the deltoid ligament is shown in Figure 64-4. The lateral collateral ligamentous complex consists of three defined ligaments. The anterior talofibular ligament (ATFL) is the weakest of these and is commonly injured in ankle sprains. The posterior talofibu- lar ligament (PTFL) extends backward from the tip of the fib- ula, and between these two the fibulocalcaneal ligament (FCL) passes vertically down to an insertion on the lateral aspect of the calcaneus. The ankle is therefore considered to have three important static stabilizers: The medial and lateral osteoliga- mentous complexes, and the syndesmosis. The relative impor- tance of these stabilizers has been widely debated, but it is clear that each has an important role. 248 A useful simplification is that two out of the three complexes should be intact for the ankle to be stable. 40,251 The anatomy of the lateral ligamentous complex is shown in Figure 64-5. Whereas the static stabilizers of the ankle have been widely characterized in cadaveric studies, it is clear that they have an uncertain relevance to the clinical situation, and this is partly explained by our relatively poor understanding of the dynamic

stability of the ankle. Axial loading fundamentally changes the behavior of the ankle, increasing the restraining effect of bony congruity and making the ankle stiffer. Moreover, six import- ant musculotendinous groups cross the ankle joint which act to stabilize as well as move the ankle. Four of these units are placed at the four “corners” of the ankle joint and act in concert. The tibialis anterior acts to dorsiflex the ankle along with the peroneus tertius, and to invert the ankle along with tibialis pos- terior, while peroneus longus and brevis act to plantarflex with tibialis posterior and to evert with peroneus tertius. Dynamic stability is provided by antagonistic contraction of these groups of muscles. Power and stability are augmented by the action of two further units: Dorsiflexion by extensor digitorum longus and extensor hallucis longus, and plantarflexion by the triceps surae (gastrocnemius and soleus), plantaris, flexor hallucis lon- gus, and flexor digitorum. Michelson et al. demonstrated that even when both the medial and lateral osteoligamentous com- plexes are completely defunctioned by injury, the talus is sur- prisingly stable: Its range of movement in relation to the mortise during the gait cycle in each of the coronal, sagittal, and trans- verse planes is no more than a single degree in excess of that of intact ankles. 248 This concept of dynamic stability is clearly highly important when considering the nature of ankle injury and repair, and suggests that the large volume of static biome- chanical data in the published literature should be viewed with extreme caution. The anatomy of the soft tissues crossing the ankle joint is shown in Figure 64-6. Structures crossing the ankle joint anteriorly pass under the superior extensor retinaculum proximal to the ankle and the Y-shaped inferior retinaculum distal to the joint. Tibialis ante- rior passes most medially and extensor hallucis longus passes adjacent to it. A safe plane for an anterior surgical approach to the ankle lies between these tendons. Lateral to the extensor

Deep anterior talotibial

Superficial talotibial

Naviculotibial (superficial)

Deep anterior talotibial

Naviculotibial (superficial)

Calcaneotibial (superficial)

Figure 64-4.  The deltoid ligament and its individual components.

2826

SECTION FOUR • Lower Extremity

hallucis lies the deep peroneal nerve and the dorsalis pedis artery, and then the tendons of extensor digitorum longus and peroneus tertius. The tendons, and the superficial peroneal nerve which lies in the subcutaneous plane, can often be seen and palpated with the ankle and toes maximally dorsiflexed. Laterally, the peronei lie deep to the peroneal retinaculum immediately posterior to the fibula. The retinaculum may be ruptured here resulting in tendon subluxation. The superfi- cial peroneal nerve emerges from the deep fascia at a variable point in the distal third of the leg before dividing: A substantial branch has been reported to lie within 5 mm of the fibula in 50% cases when measured at 10 cm from the lateral malleolar tip and in 20% cases at 5 cm from the tip, 163 leaving it vulner- able to injury in the lateral approach to the fibula. Also in the subcutaneous plane, the sural nerve lies in a variable position approximately two-thirds of the way between the distal fibula and the tendo Achilles. Medially, a number of structures run posterior to the medial malleolus under the lacinate ligament,

Anterior tibiofibular ligament Anterior

Posterior talofibular ligament

talofibular ligament

Fibulocalcaneal ligament

Figure 64-5.  The lateral ligamentous complex of the ankle and its individual components.

Saphenous nerve

Superficial peroneal nerve

Flexor digitorum longus

Tibialis posterior Posterior tibial artery Tibial nerve

Saphenous vein

Tibialis anterior

Flexor hallucis longus

Extensor digitorum longus

Tibialis anterior Extensor hallucis longus

Deep peroneal nerve Anterior tibial artery

A

Peroneus tertius tendon

Sural nerve

Lesser saphenous vein

Peroneus longus

Peroneus tertius

Peroneus brevis

Superior retinaculum

B

C

Figure 64-6.  A: Structures crossing the medial ankle. B: Structures crossing the anterior ankle. C: Structures crossing the lateral ankle.

2827

CHAPTER 64 • Ankle Fractures

of the tip of the malleolus in 20% of patients 163 : Blunt dissec- tion through fat is recommended. The periosteum should be elevated from the fracture margins only enough to allow an anatomical reduction. Strategic perforations may be made in the anterior fascia to allow the placement of reduction clamps without excessive dissection. Occasionally, the incision may be curved anteriorly at its distal extent to allow an arthrotomy and inspection of the articular surface of the ankle joint, or for access to the tubercle of Chaput. Alternatively, for posterior plating of the fibula, the incision is aligned with the poste- rior border of the fibula and the peroneal tendons are retracted away from the posterior surface of the bone. This more poste- rior location of the incision prevents satisfactory access to the AITFL and ankle joint, and will not allow fixation of a Chaput tubercle fracture. POSTEROLATERAL APPROACH This approach allows access to posterior malleolar fractures, and to the posterior aspect of the fibula and is performed with the patient prone. The longitudinal incision is made midway between the posterior border of the lateral malleolus, and the lateral border of the Achilles tendon. Blunt dissection through fat avoids injury to the sural nerve and exposes the deep fas- cia of the leg which is incised sharply. The internervous plane is between the peroneal tendons (superficial peroneal nerve) which are retracted laterally, and the FHL (tibial nerve). The FHL has muscular origins from the fibula and tibia even at this level, and should be elevated and retracted medially to expose the posterior malleolus. Classification of ankle fractures may be undertaken on the basis of anatomy, injury mechanics, or stability. While mul- tiple classification systems have been developed, only a few remain in frequent use. Pott provided the first known detailed description of ankle fractures in 1758, 308 prior to the discovery of medical radiographs in 1895, but the classification system based on the number of fractured malleoli that is commonly attributed to him may have been first described by Cooper. 70 Fractures can be classified as unimalleolar, bimalleolar, or trimalleolar based on the combined fractures of the lateral, medial, and posterior malleoli. As the number of fractured malleoli increases the prognosis worsens. 46 Despite, or per- haps because of, the simplicity of the system it remains in widespread use. Danis–Weber and AO Classifications An alternative classification developed by Danis 82 and modified by Weber, 407 describes the injury based on the location of the lateral malleolar fracture. Fractures may be classified as A, B, ASSESSMENT OF ANKLE FRACTURES CLASSIFICATION OF ANKLE FRACTURES Pott Classification

(which forms the tarsal tunnel) and their constant relationship from anterior to posterior is classically remembered according to the pneumonic Tom, Dick, and very nervous Harry: T ibia- lis posterior, flexor d igitorum, the tibialis posterior a rtery and v ein, tibial n erve, and flexor h allucis longus. Superficially in the subcutaneous plane, the great saphenous vein and nerve pass immediately anterior to the medial malleolus where the vein can be conveniently exposed for emergency vascular access, or more inconveniently damaged during the surgical approach to the medial malleolus.

SURGICAL APPROACHES FOR ANKLE FRACTURES

MEDIAL APPROACH The medial approach allows access to medial malleolar fractures and exploits an internervous interval between the dorsiflexors (deep peroneal nerve) and invertors and plantarflexors (poste- rior tibial nerve) of the ankle. Two variations exist: A straight longitudinal incision directly over the malleolus is often sim- plest and allows easy access to the fracture and the start point for screw insertion at the malleolar tip. Alternatively, a curvilin- ear incision may be made further anteriorly over the front of the medial malleolus to allow visualization of the medial corner of the plafond, curving posteriorly distal to the malleolus to allow screw or plate placement. In either case, the great saphenous vein and nerve are at risk in the subcutaneous fat as they pass just anterior to the malleolus. POSTEROMEDIAL APPROACH Although not frequently used, the posteromedial incision allows access to the posterior malleolus and can be particu- larly helpful where the fracture plane results in a posteromedial distal fragment. The incision is made longitudinally half way between the medial malleolus and the Achilles tendon. Blunt dissection will expose the fascia overlying the flexor tendons and this can be incised longitudinally well away from the back of the medial malleolus. The safest interval is found between the flexor hallicus longus (FHL) tendon (which can be iden- tified by the muscle fibers which insert into it at this level) and the peroneal tendons lateral to it. Retracting FHL medially will expose the back of the ankle joint while protecting the neurovascular bundle. Access to the malleolus more medially requires the identification and careful retraction laterally of the neurovascular bundle. LATERAL APPROACH The line of the incision is made directly over the subcutaneous border of the fibula, the length and center of the incision being dictated by the level and type of fracture present. The principle structure at risk is the superficial peroneal nerve as it pierces the deep fascia and lies in the subcutaneous fat. It is increasingly vulnerable as one moves proximally from the fibular tip, but its course is variable and a substantial branch lies within 5 cm

2828

SECTION FOUR • Lower Extremity

or C with a fracture below, at the level of, or above the syndes- mosis respectively. The distribution of fractures between these groups varies depending on the selection criteria for the study but values of 38% for A, 52% for B, and 10% for C are typical. 76 This classification remains popular and has been shown to have substantial inter- and intraobserver reliability. 231 Lindsjo 219 commented that this is a system “even an exhausted doctor on emergency call at four in the morning should be able to apply without too much error.” However, although there is a general relationship with fracture stability, it does not accurately pre- dict the presence or level of syndesmotic injury, 275 it does not address the presence (or absence) of injury to the medial side of the ankle, and the classification does not provide robust prog- nostic information. 46,182 Further work on the Danis–Weber system by the AO/ASIF group leads to the development of the AO classification of ankle fractures which has also been adopted by the Orthopae- dic Trauma Association (OTA). This classification is shown in Figure 64-7. This is far more encompassing with a total of 27 different subtypes describing injury to the bony and soft tissue structures of the ankle. 16 Acceptable interobserver reliability and ease of application have been reported. 76,79 Arthroscopic investigation of ankle fractures has shown that the degree of articular cartilage damage present corresponds with the AO subgroups from 1 to 3, 152 and therefore this extended classifica- tion may have some prognostic significance. Lauge–Hansen Classification An alternative classification system based on causative mecha- nism of injury was proposed by Ashhurst and Bromer in 1922, 18 and expanded by Lauge–Hansen in 1950 following cadaveric investigations. 208 The Lauge–Hansen classification is shown in Figure 64-8. It employs two words and a number. The first word describes the position of the foot at the time of fracture (supination or pronation), the second the deforming force at the ankle (abduction, adduction, internal rotation, or external rotation). There are four resulting classes of injury: supination external rotation (SER), pronation external rotation (PER), supination adduction (SAD), and pronation abduction (PAB). The number then refers to the progression through stages of bony and soft tissue injury. The most common pattern of injury is SER (60%) followed by SAD injuries (20%) and then those occurring in pronation (20%). 208,219,425 PAB fractures and PER fractures comprise 8% and 12% of ankle fractures, respectively. Most, but not all, ankle fractures can be classified, with reported rates between 83% 122 and 98.8%. 425 The Lauge–Hansen classifi- cation historically indicated the process of closed manipulation required to reverse displacement and reduce the fracture, but in the era of surgical fixation this classification system remains helpful in directing management. Supination External Rotation Fractures In the first stage of this injury (SER 1), the talus rotates within the mortise, pushing the tibia and fibula apart, and causing a rupture of the AITFL. This represents a stable ankle sprain. In

the second stage (SER 2), the fibula fractures at the level of the syndesmosis resulting in an oblique fracture of the fibula with a classic long posterior spike (Fig. 64-9). This is the equivalent of the AO type B fracture (see Fig. 64-7). The ankle remains stable because the medial structures are intact, the lateral mal- leolar fracture is typically minimally displaced, and thus SER 2 fractures are treated nonoperatively. In the third stage (SER 3), the posterior tibiofibular ligament ruptures or a posterior mal- leolar fracture occurs. In the fourth and final stage (SER 4), the medial aspect of the ankle is injured and the ankle becomes unstable. This may be either a rupture of the deltoid ligament, or an oblique fracture of the medial malleolus (see Fig. 64-8). Occasionally, both elements may be injured, the line of injury passing through both the deep deltoid ligament (attached to the posterior colliculus of the medial malleolus, which itself is left intact), and then through bone, resulting in an ante- rior colliculus fracture. SER 4 fractures are generally managed operatively. The oblique or spiral configuration of the fibula fracture lends itself to lag screw compression protected with a neutralization plate, or alternatively to nail stabilization. The oblique medial fracture is then most commonly treated with two parallel partially threaded cancellous lag screws placed orthogonal to the fracture. The integrity of the syndesmosis should be assessed and if found to be unstable, stabilized with a syndesmosis screw. Supination Adduction Fractures In the first stage (SAD 1), the adduction of the hindfoot results in either a talofibular ligament rupture (ankle sprain) or a transversely orientated avulsion fracture of the distal fibula, this being equivalent to an AO type A fracture (see Fig. 64-7). This is a stable injury. In the second stage (SAD 2) the medial malleolus is sheared off resulting in a diagnostic vertical fracture line (Fig. 64-10). This is an unstable injury. The medial plafond may suffer impaction from the talus and radiographs should be scrutinized carefully for this additional injury. In contradistinction to the other patterns of ankle frac- ture, surgical stabilization of an SAD 2 fracture begins with initial exposure of the medial malleolus. The area of impaction is exposed through the fracture and the joint is irrigated to remove osteochondral fragments. The impacted articular seg- ment is reduced with a lever or punch and the defect is filled with graft or graft substitute if required. The shear fracture is then typically stabilized with a buttress plate. The fibular fracture may subsequently be stabilized with a plate, a nail, or a tension band construct. Pronation Abduction Fractures In the first stage (PAB 1), the abducting talus avulses the medial malleolus (resulting in a transverse fracture line) or causes a deltoid ligament rupture. In the second stage (PAB 2) the fib- ula is pushed laterally resulting in rupture of the AITFL or an avulsion fracture of the tubercle of Chaput. In the third stage (PAB 3) the fibula fractures under compression and bending, resulting in a comminuted fracture at or above the level of the (text continues on page 2837)

2829

CHAPTER 64 • Ankle Fractures

BONE: TIBIA/FIBULA (4)

Location: Malleolar segment (44)

Types: A. Infrasyndesmotic lesion (44-A)

B. Transsyndesmotic fibula fracture (44-B)

C. Suprasyndesmotic lesion (44-C)

Groups: Tibia/fibula, malleolar, infrasyndesmotic lesions (44-A) 1. Isolated (44-A1) 2. With me- dial malleolar

Tibia/fibula, malleolar, transsyndesmotic fibula fracture (44-B) 1. Isolated (44-B1)

Tibia/fibula, malleolar, suprasyndesmotic (44-C)

3. With medial lesion and Volkmann (fracture of the postero- lateral rim) (44-B3)

3. With postero-medial

2. With me- dial lesion (44-B2)

1. Simple dia- physeal fibular

3. Proximal fibula (44-C3)

2. Multifrag- mentary frac- ture of fibular diaphysis (44-C2)

fracture (44-A3)

fracture (44-A2)

fracture (44-C1)

Figure 64-7.  The AO-OTA classification. This classification system is based upon the location of fracture lines and degree of comminution and serves to describe the severity and degree of instability associated with a particular fracture pattern. The AO-OTA classification expands on the Danis–Weber classification scheme, which is still in use and is perhaps the most rudimentary of the classification systems and is based simply on the level of the fibula fracture. The basic fracture types are shown. ( continues )

2830

SECTION FOUR • Lower Extremity

Subgroups and Qualifications: Tibia/fibula, malleolar, infrasyndesmotic, isolated (44-A1) 1. Rupture of lateral collateral ligament (44-A1.1)

2. Avulsion of tip of lateral malleolus (44-A1.2)

3. Transverse fracture of lateral malleolus (44-A1.3)

A1

Tibia/fibula, malleolar, infrasyndesmotic lesion with medial malleolar fracture (44-A2) (1) transverse

(2) oblique (3) vertical 1. Rupture of lateral collateral ligament (44-A2.1)

2. Avulsion of tip of lateral malleolus (44-A2.2)

3. Transverse fracture of lateral malleolus (44-A2.3)

A2

Tibia/fibula, malleolar, infrasyndesmotic lesion with postero-medial fracture (44-A3) 1. Rupture of lateral collateral ligament (44-A3.1) 2. Avulsion of tip of lateral malleolus (44-A3.2)

3. Transverse fracture of lateral malleolus (44-A3.3)

A3

Figure 64-7.  ( Continued ) Subtypes of “A-type” ankle fractures.

2831

CHAPTER 64 • Ankle Fractures

Tibia/fibula, malleolar, transsyndesmotic, isolated (44-B1) 1. Simple (44-B1.1)

2. Simple with rupture of anterior syndesmosis (44-B1.2) (1) in substance

3. Multifragmentary (44-B1.3)

(2) Chaput (anterior tibia) (3) Lefort (anterior fibula)

B1

Tibia/fibula, malleolar, transsyndesmotic fracture with medial lesion (44-B2) 1. Simple, rupture of medial collateral and anterior syndesmosis (44-B2.1) (1) in substance (2) Chaput (3) Lefort 2. Simple with fracture of medial malleolus and rupture of anterior syn- desmosis (44-B2.2) (1) in substance (2) Chaput (3) Lefort

3. Multifragmentary (4-B2.3) (1) rupture of medial collateral ligament (2) fracture of medial malleolus

B2

Tibia/fibula, malleolar, transsyndesmotic with medial lesion and a Volkmann (fracture of posterolateral rim) (44-B3) (1) extra-articular avulsion

(2) peripheral articular fragment (3) significant articular fracture 1. Fibula simple with medial collateral ligament rupture (44-B3.1)

2. Simple fibula fracture with fracture of medial malleolus (44-B3.2)

3. Multifragmentary with fracture of medial malleolus (44-B3.3)

B3

Figure 64-7.  ( Continued ) Subtypes of “B-type” ankle fractures. ( continues )

2832

SECTION FOUR • Lower Extremity

Tibia/fibula, malleolar, suprasyndesmotic, simple diaphyseal fracture of fibula (44-C1) 1. Rupture of medial collateral ligament (44-C1.1) 2. With fracture of medial malleolus (44-C1.2)

3. With fracture of medial malleolus and a Volkmann (Dupuytren) (44-C1.3) (1) extra-articular avulsion (2) peripheral articular fragment (3) significant articular fragment

C1

Tibia/fibula, malleolar, suprasyndesmotic, multifragmentary fibular diaphyseal fracture (44-C2)

2. With fracture of medial malleolus (44-C2.2)

3. With fracture of medial malleolus and a Volkmann (Dupuytren) (44-C2.3) (1) extra-articular avulsion (2) peripheral articular fragment (3) significant articular fragment

1. With rupture of medial collateral ligament (44-C2.1)

C2

Tibia/fibula, malleolar, suprasyndesmotic, proximal fibular lesion (44-C3) (1) fracture through neck (2) fracture through head (3) proximal tibiofibular dislocation (4) rupture of medial collateral ligament (5) fracture of medial malleolus (6) articular fragment 1. Without shortening, without Volkmann (44-C3.1) 2. With shortening, without Volkmann (44-C3.2)

3. Medial lesion and a Volkmann (44-C3.3)

C3

Figure 64-7.  ( Continued ) Subtypes of “C-type” ankle fractures. (Reprinted with permission from Marsh JL, Slongo TF, Agel J, et al. Fracture and dislocation classification compendium—2007: Orthopaedic Trauma Association classification, database and outcomes committee. J Orthop Trauma . 2007;21(10 Suppl):S1–S133.)

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CHAPTER 64 • Ankle Fractures

Supinated foot

External rotation

Adduction

I

I

Anterior tib-fib sprain

Talofibular sprain or avulsion of distal fibula

Transverse fibula or rupture of talofibular ligaments

II

II

Stable short oblique fracture of the distal fibula

Vertical medial malleolus with a transverse distal fibula and possible medial plafond impaction

III

Similar to II with additional rupture of posterior tib-fib ligament or fracture of posterior margin

Posterior malleolus or

posterior tib- fib ligament

IV

Unstable short oblique fracture of the distal fibula with a medial malleolus fracture or a deltoid ligament disruption

Figure 64-8.  Schematic diagram and case examples of Lauge-Han- sen SER and SA ankle fractures. A: A supinated foot sustains either an external rotation or adduction force and creates the successive stages of injury shown in the diagram. The SER mechanism has four stages of injury, and the SA mechanism has two stages. ( continues )

Medial malleolus or deltoid

A

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SECTION FOUR • Lower Extremity

B

C

Figure 64-8.  ( Continued ) AP ( B ) and lateral ( C ) radio- graphs show an unstable SER stage IV ankle fracture with the characteristic oblique distal fibula fracture and a medial side injury. D: An AP radiograph of an SAD ankle fracture with a transverse fibula fracture and an impacted medial malleolar fracture.

D

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CHAPTER 64 • Ankle Fractures

Pronated foot

External rotation

Abduction

I

I

Isolated medial malleolus or deltoid ligament rupture

Isolated medial malleolus or deltoid ligament rupture

Medial malleolus fracture or deltoid rupture

Medial malleolus or deltoid

II

II

Chaput's tubercle or anterior tib-fib ligament

Chaput's tubercle or anterior tib-fib

III

III

Transverse or laterally comminuted fibula with medial injury. Anteriolateral tibial

Medial injury with a high fibula fracture

impaction is also possible

IV

Similar to stage III with a posterior malleolus or tib-fib ligament injury

Posterior malleolus or

posterior tib- fib ligament

Figure 64-8.  ( Continued ) E: A pronated foot sustains either an exter- nal rotation or abduction force and creates the successive stages of injury shown in the diagram. The PER mechanism has four stages of injury, and the PAB mechanism has three stages.

E

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SECTION FOUR • Lower Extremity

A

B

Figure 64-9.  AP and lateral radiographs of a supination external rotation (SER 2) fracture (AO/OTA B1.1). Note the oblique fracture line with the long posterior spike. The talus is congruent.

A, B

C

Figure 64-10.  A supination-adduction (SAD2) fracture (AO/OTA A2.2). A: The initial AP radiograph shows impaction of the medial plafond and an avulsion fracture of the fibula. B: An intraoperative radio- graph. The impacted region must be reduced. This is achieved through the fracture using a punch or lever. Bone grafting of the defect may be required. C: At 6 months the fractures are united. Note the buttress plating of the shear fracture. A fibular nail has been used to stabilize the fibular fracture.

2837

CHAPTER 64 • Ankle Fractures

syndesmosis (Fig. 64-11). Operative treatment of this fibular fracture differs from that of an SER 4 fracture in that lag screw fixation of the comminuted region is often not possible, and an alternative strategy of bridge plating with a small fragment DCP or equivalent, rather than a 1/3 tubular plate, or an intramedul- lary nail may be required. The medial fracture can be addressed with orthogonal cancellous lag screws as for the SER fracture, or with a tension band construct if the fragment is small. The integrity of the syndesmosis should be assessed. Pronation External Rotation Fractures In the first stage (PER 1), an isolated medial malleolar fracture (or deltoid rupture) is produced. In the second stage (PER 2), either the AITFL is ruptured or a tubercle of Chaput fracture occurs. In the third stage (PER 3), a fracture of the fibula occurs through torsion resulting in an oblique or spiral fracture. This differs from the SER fracture in that it is typically suprasyndes- motic (equivalent to an AO type C fracture) and that the long spike at the proximal extent of the fracture is anterior (i.e., the fracture line passes from distal posteriorly to proximal anteri- orly). A PER 3 fracture is unstable and there is a high associ- ated incidence of syndesmosis injury. The classic variant is the so-called Maisonneuve fracture (Fig. 64-12), which may not be diagnosed correctly unless suspected and looked for. Surgical stabilization of the fibular fracture is with a plate if it occurs within 5 or 6 cm of the syndesmosis, with or without a syn- desmosis screw. Fractures above this level are most commonly treated with syndesmosis screw(s) alone. The medial malleolar fracture is commonly treated with cancellous lag screws. Despite the utility of the Lauge–Hansen classification system, later investigators have not been able to replicate the stages of injury described in the original experiments, 137,249 and more recently an innovative study comparing the mechanism of injury

as seen on “YouTube” movie clips and the subsequent x-rays of the same patient failed to find a strong correlation between mechanism and fracture pattern. 205 In common with other classi- fication systems, it does not provide reliable information regard- ing the presence or absence of syndesmotic rupture. 122,274,425 Like most detailed classification systems, reproducibility is modest with interobserver variability of between 43% and 60% and intraobserver variability of between 64% and 82%. 273,377 How- ever, the classification system does have prognostic significance: The degree of articular damage has been shown to correlate with the stage of injury. 215 Eponymous Terms A number of eponymous terms have also survived by custom and common usage. A Volkmann’s fracture refers to a fracture of the posterior malleolus, 400 although the fracture was first described by Earle, the grandson of Sir Percival Pott. 98 A Maison- neuve fracture is a fracture of the proximal fibula associated with a medial malleolar fracture or deltoid ligament injury, account- ing for 5% of all ankle fractures, 293 although Maisonneuve actually described a number of fractures of both the proximal and distal fibula in association with a rotational injury. 228 It is important to exclude this proximal fracture in rotational ankle injuries as it is highly unstable despite potentially normal ankle radiographs. The proximal tibia should be carefully palpated and, where there is tenderness, full-length views of the tibia and fibula should be obtained (Fig. 64-12). CLINICAL ASSESSMENT OF ANKLE FRACTURES Assessment of an ankle fracture requires a detailed history, a thorough physical examination and radiographic imaging. While the patient’s own account of a low-energy twisting injury

A, B

C

Figure 64-11.  A pronation abduction (PAB3) fracture (AO/OTA C2.3). A: The initial radiograph shows a medial malleolar fracture, a comminuted suprasyndesmotic fibular fracture and a diastasis. B: The medial malleolar fracture has been stabilized with two screws and the fibular fracture with a bridging plate. A diastasis screw has been inserted. C: An intramedullary nail can be used for the fibula.

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SECTION FOUR • Lower Extremity

Figure 64-12.  Maisonneuve frac- ture. A: An AP radiograph of the ankle and tibia and fibula shows a PER 3 Maisonneuve fracture (AO/OTA C3.1). B: External rota- tion shows lateral displacement of the talus and widening of the syndesmosis.

A

B

ankle rules 357 (Table 64-1) provide assistance in determining the need for x-ray. They offer a highly sensitive 22 and cost- effective 15,358,359 method of identifying those patients, presenting with ankle injuries, that are most likely to have sustained a frac- ture. While Stiell et al. 359 have demonstrated the effectiveness of these rules in a number of centers, other authors have reported difficulties in disseminating the rules, 54 and their applicability in certain patient groups such as diabetics has been questioned. 66

may reveal little due to the speed of the event, an apprecia- tion of the energy transfer involved is important as high-energy mechanisms indicate the likelihood of additional soft tissue complications, compartment syndrome, 30,303,428 the presence of the more complex pilon fracture, or other associated injuries. Certain comorbidities in particular are of importance: Diabetes will not only require preoperative work-up and perioperative blood sugar management, but also indicates an increased likeli- hood of wound complications owing to immunologic and vas- cular impairment. Poorly controlled diabetics in particular are at risk of peripheral neuropathy, which may influence postop- erative weight-bearing decisions. A history of smoking, alcohol abuse, and psychiatric illness similarly increases the likelihood of complications. Clinical examination begins with inspection for deformity, bruising, blistering, skin integrity, and color. A careful palpation of the limb then starts at the fibular head and progresses sequentially down the lateral aspect of the leg to the lateral malleolus and the soft tissues anterior and posterior to it before moving medially across the ankle joint to the medial malleolus and its adjacent soft tissue structures. Palpation of the skeleton of the foot will exclude commonly associated (or missed) injuries such as fractures of the metatarsals or lateral talar process, or disruption of the midtarsal (Lisfranc) articula- tion, which can occur following a similar mechanism. Palpation of the Achilles tendon and the Simmonds 347 or Thompson’s 376 test exclude rupture of this structure. A distal neurovascular assessment includes assessment of temperature and capillary refill. Skin marking of palpable dorsalis pedis and posterior tibial arterial pulsations at presentation will be helpful in later assessment if the condition of the limb deteriorates. The Ottawa

IMAGING AND OTHER DIAGNOSTIC STUDIES FOR ANKLE FRACTURES Radiography

The three standard radiographs are an anteroposterior (AP), a lateral, and a mortise projection of the ankle. Tenderness of the proximal fibula should be investigated with a full-length radio- graph of the leg. A mortise view of the ankle taken in 15 degrees of internal rotation is extremely helpful in assessing the lateral aspect of the ankle which is often poorly seen on the AP view because of the frustral shape of the talus and consequent over- lap of the tibia, fibula, and talus (Fig. 64-13).

TABLE 64-1. Ottawa Ankle Rules

Pain exists near one or both of the malleoli plus one or more of the following: • Age > 55 years old • Inability to bear weight • Bone tenderness over the posterior edge or the tip of either malleolus

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CHAPTER 64 • Ankle Fractures

A, B

C

Figure 64-13.  Anteroposterior ( A ), mortise ( B ), and lateral ( C ) radiographs of the ankle. These constitute a standard ankle trauma series.

Interpretation of the radiographs follows the sequence ABCS, and includes an assessment of technical a dequacy and align- ment (does this radiograph show the joint well enough for you to make a complete assessment?), the cortical outline and tra- becular morphology of each of the b ones, particularly the artic- ular margins where irregularity of the c artilage articular surface,

although not directly visible, can be inferred, and the contour of the overlying s oft tissues. The relationship between the bony components of the ankle is critical, and a number of “normal” features are widely recognized (Table 64-2; Figs. 64-14 and 64-15). These empirical “normal” measurements must, how- ever, be interpreted in the light of some scientific controversy

TABLE 64-2. Radiographic Parameters That Should Be Looked for on Radiographs of Ankle Fractures

Radiographic Feature

Accepted Normal Parameter

Notes

Medial clear space

The joint spaces medial and superior to the talus should be equal. The medial clear space should be < 5 mm, and no more than 2 mm greater than the tibiotalar clear space.

These measurements are influenced by rotation, individual patient morphology, and the presence of ankle arthritis.

> 5 mm

Tibiofibular clear space (syndesmosis A) 10 mm above joint line

Relatively constant with rotation

< 5 mm on AP view and < 1 mm on the mortise view

Tibiofibular overlap (syndesmosis B) 10 mm above joint line

Highly variable dependent on rotation

Fibular length

The articular margins of the distal fibula and the lateral process of the talus on the mortise view should be parallel, and equal to the tibiotalar joint space. The “ball sign” (Fig. 64-15) is a confirmatory visual cue.

Shortening of the fibula results in lateral and valgus subluxation of the talus

Talocrural angle

Approximately 83 degrees, and symmetrical with contralateral ankle.

A further measurement of fibular length

Medial malleolus

Less than 2 mm displacement

Important where this results in talar shift

Lateral malleolus displacement

Less than 2 mm shortening, or displacement posteriorly or proximally

Important where this results in talar shift. Isolated lateral malleolar fractures, although commonly displaced, are not usually an indication for surgery. The size may be underappreciated on plain x-ray.

Posterior malleolus displacement

The fragment must be less than 25% of the ankle joint seen on the lateral radiograph, and less than 2 mm displaced.

Note: A diagrammatic representation of these parameters is shown in Figure 64-14, and the ball sign is explained in Figure 64-15.

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SECTION FOUR • Lower Extremity

the importance of more subtle degrees of abnormality remain uncertain and controversial. Radiographic interpretation is often a clinical judgment made in the light of the individual circumstances of the injury, the clinical features present, and the state of health and functional requirements of the patient. Axial Imaging Neither CT nor MRI is used routinely in the investigation of ankle fractures. CT scanning is helpful in characterizing joint displacement in pilon fractures, assessing the size of a poste- rior malleolar fragment, and in assessing the accuracy of the reduction of the syndesmosis postoperatively (Figs. 64-16 and 64-17). MRI has been used in the experimental setting to assess the integrity of the deep deltoid ligament where this is uncer- tain, but this is not common practice. Additional osteochondral lesions are not infrequently identified on MRI scans, but the importance of these remains uncertain. The vast literature on the treatment of ankle fractures is replete with small heterogeneous case series reporting the outcome of a bewildering variety of management strategies, using disparate outcome assessments. Critical review of this literature suggests that satisfactory outcomes can be obtained with a variety of treatments, but equally that the indiscriminate use of surgery does not necessarily improve outcomes and exposes the patient to additional complications. A satisfactory outcome after ankle fracture can be anticipated when the joint is congruent (the talus is placed anatomically under the plafond) and stable (it remains there until fracture healing). TREATMENT OPTIONS FOR ANKLE FRACTURES

Mortise view

Tibiofibular clear space (A)

Tibiofibular overlap (B) Medial clear space

Ball sign

A

B

Normal

Talocrural angle

Figure 64-14.  Radiographic measurements. See Table 64-2 for expla- nation. The ball sign is explained in Figure 64-15.

and uncertainty. There is substantial variability in “normal” anatomy between individuals, and comparison views of the contralateral side are occasionally helpful. Absolute measure- ments are also affected by magnification, and the degree of axial rotation of the limb. 129 Pneumaticos et al. 304 have demonstrated that, for example, the size of the medial clear space more than doubles depending upon the rotational position of the limb, and there is a significant increase in medial clear space with ankle plantarflexion, a common trap for the unwary. 198,328 More- over, the accuracy of plain radiographic measurements has been questioned in the light of CT studies that have shown that a number of assumptions based on the interpretation of a two-di- mensional radiographs are simply not accurate. 138,149 While both a perfectly normal radiograph, and one with clear displacement, can usually be recognized with confidence,

A

B Figure 64-15.  A: The “ball” sign is described on the AP view as an unbroken curve connecting the recess in the distal tip of the fibula and the lateral process of the talus when the fibula is out to length. B: If the fibula is short and malreduced the ball sign is absent.