Ankle fractures in adults

INTRODUCTION — 

Ankle fractures are increasingly common injuries that necessitate a careful evaluation to determine proper management. This topic provides an overview of ankle fractures that result from minor trauma (ie, indirect or low-energy fractures), including a basic approach to their evaluation and management. Ankle sprains and other ankle and foot injuries, fibular fractures above the ankle, tibial fractures, and other lower extremity injuries, including severe injuries sustained through major trauma, are discussed separately:

●Ankle sprains and tendon injuries (see "Ankle sprain in adults: Evaluation and diagnosis" and "Syndesmotic ankle injury (high ankle sprain)" and "Achilles tendinopathy" and "Non-Achilles ankle tendinopathy" and "Achilles tendon rupture")

●Foot injuries and conditions (see "Midfoot pain in adults: Evaluation, diagnosis, and select management of common causes" and "Hindfoot pain in adults: Evaluation and diagnosis of common causes" and "Overview of foot anatomy and biomechanics and assessment of foot pain in adults")

●Tibia and fibula fractures (see "Fibula fractures" and "Overview of tibial fractures in adults")

●Severe extremity trauma (see "Severe lower extremity injury in the adult patient" and "Acute compartment syndrome of the extremities")

EPIDEMIOLOGY AND RISK FACTORS — 

The incidence of ankle fractures is approximately 187 fractures per 100,000 people each year [1]. Since the mid-1900s, this rate has increased significantly in many industrialized countries, most likely due to growth in the number of people involved in athletics and in the size of the elderly population [1-3].

The vast majority of ankle fractures are malleolar fractures: 60 to 70 percent occur as unimalleolar fractures, 15 to 20 percent as bimalleolar fractures, and 7 to 12 percent as trimalleolar fractures [1,4]. There are similar fracture rates overall between women and men, but for most fractures men have a higher rate as young adults, while women have higher rates in the 50- to 70-year age group [1,4].

Cigarette smoking and a high body mass index have been associated with ankle fractures [5,6]. In contrast with fractures of the radius and other fractures common among perimenopausal and postmenopausal women, bone density has not been clearly demonstrated to be a major risk factor [7]. Diabetes increases the risk for a wide range of fractures including the ankle. (See "Bone disease in diabetes mellitus", section on 'Bone fracture'.)

CLINICAL ANATOMY — 

The bony anatomy of the ankle consists of the articulation of the distal tibia and fibula with the talus (figure 1 and figure 2 and figure 3). These bones are held together by the ligaments of the ankle to form a mortise. The weight-bearing portion of the mortise consists of the tibial plafond and the talar dome. The mortise gains its stability from the bony relationships of the ankle and from surrounding structures.

The lateral ligament complex consists of the anterior talofibular ligament, the calcaneofibular ligament, and the posterior talofibular ligament (figure 4). The medial ankle complex consists of the deep and superficial fibers of the deltoid ligament (figure 5). The peroneal tendons, anterior and posterior tibialis tendons, Achilles tendon, and joint capsule provide additional support (figure 6).

The syndesmosis of the ankle refers to the articulation of the distal tibia and fibula (figure 7). Support is provided by the anterior tibiofibular ligament, the posterior tibiofibular ligament, the transverse tibiofibular ligament (posteriorly), and the interosseous membrane, which extends from the ankle proximally. These structures prevent the distal tibia and fibula from separating. Abnormal forces that rotate the talus within the mortise push the tibia and fibula apart and may cause an injury to the syndesmotic ligaments or a fracture.

The motion of the ankle is complex (figure 8). Although the joint moves primarily in the sagittal plane to enable dorsiflexion and plantarflexion of the foot, motion occurs in several planes. Inversion and eversion of the foot occur mainly at the subtalar joint [8].

The talar dome is narrower posteriorly (figure 9). It therefore fits more tightly into the mortise, creating greater joint stability, when the ankle is dorsiflexed [3,9]. The position of the talus in the mortise depends more on the medial supporting structures, which are stronger, than the lateral structures. Therefore, the ankle is better able to withstand forces that stress the medial side of the joint [10].

The posterior tibial artery and tibial nerve run together just posterior and lateral to the medial malleolus (figure 10). The anterior tibial artery (dorsalis pedis artery in the foot) and deep peroneal nerve run together and cross the ankle joint anteriorly (figure 11 and figure 12), approximately in the midline, just lateral to the extensor hallucis longus and below the extensor retinaculum.

There is no single, widely accepted definition of the anatomic margins of the lateral malleolus (figure 13). For the purpose of this review, the lateral malleolus refers to the distal part of the fibula that articulates with the talus and distal tibia. Lateral malleolar fractures are those that lie between the distal tip of the fibula and the most proximal portion of the fibula that lies directly adjacent to the tibia in the tibial groove (image 1).

The lateral malleolus provides stability against excessive eversion of the ankle and foot. The medial malleolus is the most distal part of the tibia and articulates with the medial aspect of the talar dome (figure 3). The posterior aspect of the distal tibia is commonly referred to as the posterior malleolus. It primarily includes the portion of the tibia where the syndesmotic ligament complex attaches.

MECHANISM OF INJURY

Overview of mechanisms — Ankle injuries that result from bending forces are commonly described as inversion or eversion injuries. Technically, inversion and eversion are motions of the subtalar joint and become supination and pronation when combined with ankle and midfoot motion. Internal and external rotation of the ankle refers to the rotation of the talus within the joint.

Supination (inversion) injuries typically cause distraction of the lateral ankle structures and compression of the medial structures. Pronation (eversion) injuries cause medial distraction and lateral compression. Structures being distracted (or stretched) generally fracture or tear before structures being compressed. As an example, injuries that occur while the ankle is supinated will result in damage to the distal fibula and its associated ligaments, which are being stretched, before any damage occurs to the distal tibia and its deltoid ligament complex.

In addition to bending forces, rotational forces often contribute to ankle injuries by placing further stress on supporting structures and forcing the malleoli apart.

Classification schemes — A complete discussion of classification systems is beyond the scope of this review and can be found separately [3,11].

One classification scheme deserves mention because of its simplicity and clinical relevance. In this approach, the ankle is conceived as a ring of supporting structures surrounding the talus (figure 14) [9]. Supporting structures may be ligaments or bones. If the ring is broken at one site, the injury is stable and can be managed nonoperatively; if the ring is broken at two or more sites, the injury is unstable and generally is managed operatively.

Historically, orthopedists have classified the mechanism of injury using two descriptors. The first describes the position of the ankle at the time of injury; the second refers to the force applied to the ankle that causes the injury. As an example, a "supination/external rotation" injury refers to the ankle in a supinated position with an external rotation force applied to it. These descriptors predict the sequence in which structures are injured and provide the basis for the Lauge-Hansen system of ankle fracture classification (figure 15) used to guide orthopedic decision-making. The amount of force sustained during the injury is a third factor, in addition to ankle position and force direction, which determines the type and extent of injury. Several studies question the accuracy of the Lauge-Hansen scheme [12,13].

The Danis-Weber classification scheme categorizes fractures of the lateral malleolus (fibula) depending on the location of the fracture relative to the syndesmosis (or mortise) (figure 16 and figure 17).

Malleolar fractures — Isolated malleolar fractures tend to be stable if they are nondisplaced, in other words, there is no significant contralateral injury of ligaments or bone and no syndesmotic injury. However, each fracture type may be associated with injury to other ankle structures. As an example, fractures of the medial malleolus that appear to be isolated during initial assessment may be associated with disruption of lateral or posterior structures.

Posterior malleolar fractures occur either from the impact of the talus on the posterior aspect of the tibia (often as part of a pilon fracture (image 2)) or from an external rotation or pronation (eversion) force. They can occur in association with disruption of the posterior tibiofibular ligament. Posterior malleolar fractures rarely occur in isolation [14]. They are more commonly associated with fibular fractures and additional ligament damage, and they are generally unstable injuries.

Fractures of both the lateral and medial malleoli are called bimalleolar fractures and are generally unstable. A bimalleolar fracture with a fracture of the posterior malleolus is referred to as a trimalleolar fracture. Trimalleolar fractures are unstable and typically occur from trauma of greater force. They have a higher risk of complication than bimalleolar fractures and require surgical stabilization.

CLINICAL PRESENTATION AND EXAMINATION — 

Emergency conditions, such as an open fracture, neurovascular compromise, or fracture dislocation, must be treated immediately. (See 'Initial treatment' below.)

In addition to the mechanism of injury, the clinician’s history should ascertain the following:

●Site of the most significant pain

●Other injured areas (eg, lumbar spine, hip, knee)

●Length of time from injury to presentation

●Neurovascular symptoms

●Ability to bear weight

●History of any previous injury or surgery

●Related comorbidities (eg, diabetes)

An ankle fracture, particularly one sustained in a fall from a height, may be associated with other injuries such as a lumbar compression or pelvic fracture. (See "Thoracic and lumbar spinal column injury in adults: Evaluation" and "Pelvic trauma: Initial evaluation and management".)

Clinicians should inspect the injured ankle for:

●Swelling

●Deformity

●Skin abnormalities, such as lacerations (possible open fracture), tenting, or blistering (caused by rapid stretching of the skin)

The degree of swelling is not a reliable guide to the presence of a fracture.

Clinicians should palpate the ankle looking for the point of maximal tenderness and other tender areas. The examiner should palpate the full length of the tibia and fibula, especially the fibular neck, to evaluate for possible associated fractures. Testing for ligamentous laxity can be deferred until after radiographs are obtained; it is often not tolerated in the setting of an acute fracture.

Pulses of the dorsalis pedis and posterior tibialis arteries and distal capillary refill should be checked. Sensation and motor function should be assessed. A detailed discussion of the physical examination of the ankle is provided separately. (See "Ankle sprain in adults: Evaluation and diagnosis".)

Once emergency conditions have been ruled out, the first priority in the evaluation is to determine whether the fracture is stable and can be managed nonoperatively or unstable and must be referred. Typically, an ankle fracture is stable if it meets the following criteria:

●It is isolated to the lateral, medial, or posterior malleolus.

●It is nondisplaced and at or below the level of the mortise.

●It is not associated with a ligamentous injury.

An ankle fracture is unstable if two or more sites of significant injury are present, such as a lateral malleolar fracture with deltoid ligament disruption or a bimalleolar fracture. (See 'Indications for orthopedic consultation or referral' below.)

DIAGNOSTIC IMAGING

Initial approach to imaging — The Ottawa Ankle Rules have been shown to help the examiner determine whether radiographs of the ankle or foot are needed in the evaluation of an acute ankle injury (figure 18).

Patients who do not meet the Ottawa criteria are unlikely to have a fracture, and radiographs are typically not needed in the acute setting [15]. A full discussion of the Ottawa rules is found separately. (See "Ankle sprain in adults: Evaluation and diagnosis", section on 'Ottawa ankle rules'.)

Suspected ankle fractures are typically evaluated using plain radiographs (image 3). Anterior-posterior (AP), oblique, and lateral (image 4) views are standard. The oblique radiograph, also called the mortise view (image 5), should be obtained as an AP projection with a 10 to 20 degree lateral angle to help visualize injuries of the syndesmosis and talus. On the mortise view, the relationship of the medial and lateral malleoli can be measured with respect to the talus. Normally, the distances between the talus and the lateral malleolus, the talus and the medial malleolus, and the talus and the tibial plafond are uniform throughout the mortise view.

Isolated lateral and medial malleolar fractures are best seen on the AP view (image 6 and image 7). Posterior malleolar fractures are best seen on the lateral view (image 4 and image 8). On the mortise view, discrepancies in the relationship between the talus and the medial and lateral malleoli can help identify an unstable fracture or soft tissue injury (image 9 and image 10).

Determining stability of isolated lateral malleolus fractures

Primary role of plain radiographs — The presence or absence of medial injury determines the stability of lateral malleolar fractures. Weight-bearing, manual stress, and gravity stress radiographs have been used to determine joint stability in cases of lateral malleolar fracture with no widening of the medial joint on initial plain radiographs [16,17]. Manual stress views are generally no longer performed, while gravity stress views are more prone to false-positive results than weight-bearing views. Weight-bearing radiographs allow for measurement of the medial joint space under a controlled stress [16,17].

A distance greater than 4 mm measured between the talus and medial malleolus (an interval known as the medial clear space) on either a standard or weight-bearing mortise radiograph (image 11 and image 10) raises concern for a deltoid ligament injury and an unstable fracture [8,17,18]. The medial clear space is normally slightly greater in tall and male patients, with a range of 3.1 to 4.5 mm in adult males and 2.4 to 3.4 mm in adult females [19].

Accurate weight-bearing radiographs require the patient to bear at least 50 percent of their bodyweight on the injured ankle while a mortise view is obtained (picture 1). A bathroom scale can be used to confirm adequate stress is being applied [17]. If weight-bearing at the initial evaluation is too painful, the ankle should be immobilized and the patient seen in one week for another attempt. If the patient remains unable to tolerate sufficient weight-bearing at that time, a mortise view using gravity stress can be obtained [17]. If any uncertainty remains, the patient should be referred to an appropriate surgeon for further assessment and possible advanced imaging.

Stress radiographs are unnecessary if weight-bearing radiographs show a stable joint [17]. Furthermore, the gravity stress mortise radiograph has been shown to be as sensitive and specific as a manual stress mortise radiograph (picture 2) [18,20]. If adequate weight-bearing or gravity stress radiographs cannot be obtained, the patient should be referred for specialty consultation.

If weight-bearing radiographs prove insufficient or additional anatomic detail is needed, the integrity of the deltoid ligament can be assessed with magnetic resonance imaging (MRI) or ultrasound [21,22]. MRI can reveal deltoid ligament injury, but findings may not correlate with functional stability, and thus MRI is less useful for decision-making based on the stability of lateral malleolar fractures [23].

Role of ultrasound — When clinicians skilled in musculoskeletal ultrasound perform the examination, ultrasound demonstrates high accuracy for determining the presence and severity of a deltoid ligament injury [22,24]. However, controlled studies demonstrating a correlation between ultrasound findings and functional stability or good long-term outcomes with nonsurgical treatment are lacking. Therefore, weight-bearing radiographs are still needed to assess the stability of isolated lateral malleolar fractures when a partial deltoid ligament injury is detected by ultrasound. If a complete deltoid ligament injury is identified or if uncertainty remains about the extent of a deltoid injury, the patient should be referred to surgery for further assessment.

Determining stability of medial malleolus fractures — Isolated medial malleolar fractures are considered stable if no associated ligament injury or significant tibiotalar joint displacement is apparent on weight-bearing plain radiographs. Fracture displacement must be 2 mm or less, and joint surface involvement must be 25 percent or less [8,10,14].

Determining stability of posterior malleolus fractures — In the case of isolated posterior malleolar fractures, the mortise must be uniform and appear stable on weight-bearing radiographs. No displacement on lateral radiograph is acceptable. If it is unclear whether displacement is present on plain radiograph, a computed tomography (CT) scan should be obtained [25]. Weight-bearing radiographs are especially important for the assessment of posterior malleolus injury, as these injuries can be associated with syndesmotic injury and instability. Fracture fragment size may be a more important factor when determining clinical instability. Fractures of the posterior malleolus that involve 25 percent or more of the tibial plafond are generally unstable and should be referred. If the conditions for stability are not met, referral is necessary. (See 'Indications for orthopedic consultation or referral' below.)

Advanced imaging — In some clinical circumstances, including several described below, advanced imaging is needed. Often, it is best to request such studies after consulting with the orthopedic surgeon who will assume care should an unstable or otherwise complex injury be identified. Cone beam CT may provide greater accuracy than plain radiographs while delivering comparable radiation doses [26].

●Soft tissue injury suspected – If plain films are negative but clinical suspicion is high for significant soft tissue or cartilage injury, MRI is more useful than CT (image 12 and figure 3).

●Assessment of isolated malleolus fracture – MRI is less useful for evaluation of isolated malleolar fractures, as functional stability of the ankle ligaments is better assessed with weight-bearing rather than static images [23]. (See 'Determining stability of isolated lateral malleolus fractures' above and 'Determining stability of medial malleolus fractures' above.)

●Talus fracture suspected – If a fracture of the talus is suspected (eg, focal tenderness, possible fracture line on plain radiograph), or if significant comminution is present, a CT scan helps to delineate the extent of injury and fracture displacement. (See "Talus fractures".)

●Osteochondral injury to talar dome suspected – MRI is the preferred study to assess suspected or incompletely imaged injury to the cartilage of the talar dome. (See "Talus fractures".)

●Stress fracture suspected – Both MRI and triple-phase bone scintigraphy (bone scan) (image 13) are helpful in diagnosing a stress fracture in the ankle region, especially if plain radiographs are normal. (See "Overview of bone stress injuries and stress fractures", section on 'Imaging studies'.)

INDICATIONS FOR ORTHOPEDIC CONSULTATION OR REFERRAL — 

Open fractures and any injury with associated neurologic or vascular deficits require immediate surgical consultation.

The two major indications for operative fixation of an ankle fracture are loss of joint congruency or loss of joint stability [3,8,10]. Loss of joint congruency, such as occurs with severe posterior malleolar fractures and pilon fractures, occurs in the setting of more severe trauma (pilon fractures occur when relatively strong axial forces drive the tibial plafond into the talar dome (image 2)). Fractures that create joint instability as a result of minor trauma are more common.

Typically, an ankle fracture is unstable if two sites of significant injury are present. All trimalleolar, bimalleolar, and isolated malleolar fractures associated with a ligament rupture on the opposite side (eg, a lateral malleolar fracture with deltoid ligament disruption) are unstable and require orthopedic referral. Fractures of the posterior malleolus that involve 25 percent or more of the tibial plafond are generally unstable and should be referred.

If there is any uncertainty about the stability of the ankle, the patient should be referred. Unstable fractures are generally managed surgically, although in some instances clinicians with the necessary expertise may treat them with molded casting [27].

Injuries that lead to a distal fibular fracture above the tibiotalar joint line are almost always associated with a syndesmotic disruption and should be referred to an orthopedist (image 14 and image 15 and image 16). Posterior malleolar fractures that result in any loss of joint congruency should also be referred.

Unstable fractures often require open reduction with internal fixation. Whether operative or nonoperative management is used, the goal of treatment is anatomic alignment to maximize function and minimize the risk of posttraumatic osteoarthritis.

TREATMENT

Initial treatment — Emergency conditions, such as an open fracture or neurovascular impairment, require immediate surgical consultation and treatment. Fracture dislocations must be reduced immediately to prevent severe complications, such as avascular necrosis.

Once emergency conditions are excluded, clinicians should evaluate the fracture more closely, focusing on any malalignment or instability, to determine proper management and follow-up. (See 'Indications for orthopedic consultation or referral' above.)

The ankle should be immobilized at 90 degrees (ie, neutral position) to provide support and control pain. Usually, a short-leg posterior splint is sufficient. A sugar-tong (ie, coaptation) splint can be added for additional mediolateral support. If significant swelling or deformity is present, adequate padding should be placed prior to applying the splint to allow for further swelling while maintaining stability.

For stable, nondisplaced, isolated malleolar fractures, a walking boot (picture 3) or a posterior splint (sufficiently strong to withstand weight-bearing) (figure 19 and picture 4) typically provides adequate immobilization and pain control until follow-up [23]. Crutches can be provided for patients requiring partial weight-bearing. Evidence for isolated medial malleolus fractures is limited, but many patients with such injuries are unable to bear weight.

Patients awaiting orthopedic consultation or surgery should remain non-weight-bearing in a splint if needed or weight-bearing as tolerated if symptoms are manageable. If surgery is planned in the acute setting, excessive use of narcotic analgesics should be avoided, if possible, until the orthopedic surgeon is able to explain the procedure and obtain informed consent. Management of specific fracture types is discussed immediately below.

The patient should be instructed to rest the ankle, apply ice, use a compression bandage not applied too tightly, and elevate the injured ankle above the level of the heart as able. Over-the-counter analgesics may be used. The patient should be reassessed if pain is not adequately controlled with these basic measures. (See "General principles of acute fracture management", section on 'Pain management'.)

Clinicians should instruct the patient to call immediately for:

●Pain that is severe or increasing

●Numbness that is new or worsening

●Skin discoloration (eg, dusky toes) distal to the splint

These complaints may represent vascular compromise or some other serious complication and should be investigated immediately. Any patient complaint of skin irritation, a splint which has become excessively tight or loose, or a splint which has gotten wet should also be assessed. An examination and repeat radiographs to check for acceptable alignment are generally performed during the first follow-up visit at 7 to 10 days.

Management of specific malleolar fractures — There is little high-quality evidence to determine the best treatment of ankle fractures [28]. Our recommendations below are based upon limited randomized trials, observational data, and clinical experience.

Lateral malleolar fractures — In all cases of an isolated fracture of the lateral malleolus, the ankle joint must be carefully assessed for stability. The location of such a fracture relative to the tibiotalar joint line (ie, mortise) can help to determine if it is stable (algorithm 1):

●Fracture below joint line – Fractures below the level of the mortise (image 17) are typically stable and less likely to be associated with additional ligament injuries.

●Fracture above joint line – Fractures above the level of the mortise (image 14 and image 15 and image 16) are typically unstable due to associated syndesmosis injury and should be referred for surgical evaluation. (See 'Indications for orthopedic consultation or referral' above.)

●Fracture at joint line – The stability of isolated lateral malleolar fractures at the level of the mortise (image 6 and image 10 and image 18) depends upon the integrity of the medial structures (mainly the deep deltoid ligament and the medial malleolus) [15]. The presence of a lateral malleolar fracture together with a medial fracture or deltoid ligament injury significantly increases the risk of joint instability, even if alignment is well maintained (image 9) [8].

Instability requiring surgical referral is demonstrated by 2 mm or more of displacement of the fibular fracture, an associated medial fracture, or widening of the medial clear space on weight-bearing radiographs (image 11 and image 10). Medial swelling, ecchymosis, and tenderness suggesting deltoid ligament injury should be documented, but weight-bearing radiographs are needed to identify accurately whether the fracture is stable [17]. (See 'Determining stability of isolated lateral malleolus fractures' above.)

Uncertainty about the stability of medial structures indicates the need for weight-bearing radiographs, or a gravity stress mortise view if weight-bearing cannot be tolerated (picture 2) [18]. If medial instability is demonstrated or suspected, orthopedic referral should be obtained. If the medial structures are intact and there is minimal fibular displacement, nonsurgical treatment has a high success rate [29,30]. Stress radiographs are described above. (See 'Diagnostic imaging' above.)

Two long-term follow-up studies of patients with isolated lateral malleolar fractures at or below the level of the ankle joint report that greater than 90 percent of patients had good clinical results regardless of treatment, provided fibular displacement did not exceed 3 mm [29,30]. Other studies comparing operative with nonoperative treatment of isolated lateral malleolar fractures have shown no significant difference in outcomes [5-7,10,31]. Based upon such studies, treatment for isolated lateral malleolar fractures is primarily nonoperative.

If the isolated fracture is oblique through the lateral malleolus at or below the mortise, and there is no sign of instability, the patient may be treated in an ankle brace or removable cast boot, with the ankle held in neutral position, for three to six weeks, with weight-bearing as tolerated (image 18) [23].

Weight-bearing radiographs should be repeated 7 to 10 days after the injury for oblique fractures to ensure that alignment remains acceptable and again at four to six weeks to assess healing [8]. At each follow-up visit, the ankle should be examined for signs of associated injury or other complications, including those caused by an improperly fitting orthosis (eg, nerve compression). Examination should include inspection of the skin and assessment of neurovascular function.

Once healing is evident (ie, nontender over fracture site and radiographic evidence of adequate callus around the fracture), the patient may begin unsupported weight-bearing and rehabilitation. If healing is insufficient, the ankle should be immobilized or braced for an additional two weeks and then reassessed. Persistent pain and a lack of callus formation should prompt orthopedic referral.

Treatment in a removable cast boot causes less discomfort and loss of mobility, and no change in long-term outcomes, according to a small number of clinical trials [32-34]. A systematic review and meta-analysis of five studies involving 516 patients with stable, lateral malleolus fractures (Danis-Weber type B) reported fewer complications and no difference in functional outcome in patients treated with removable orthosis (ie, brace or boot) compared with short-leg cast [34].

The results of a randomized trial suggest that immobilization for three weeks in a short-leg walking cast or properly fitting rigid ankle orthosis further reduces the short-term loss of ankle mobility and the risk for deep vein thrombosis compared with treatment in a short-leg walking cast for six weeks, without compromising healing [35]. While further study is needed to confirm the effectiveness of limiting immobilization to three weeks, evidence in support of shorter periods of immobilization is growing.

Treatment of fractures of the proximal fibula and fibular shaft are discussed separately. (See "Fibula fractures".)

Nondisplaced isolated medial or posterior malleolar fractures — Care must be taken with these fractures to confirm the absence of associated injuries causing ankle instability. Fractures with associated injuries, such as a proximal fibular fracture or ligament injuries creating instability, are referred to an orthopedic surgeon. Fractures of the posterior malleolus that involve 25 percent of the tibial plafond or more should be referred.

Fractures that are truly nondisplaced, isolated injuries that appear stable on weight-bearing radiographs (image 7) can be treated initially in a walking boot or brace (picture 3) or a posterior, short-leg splint. Weight-bearing is as tolerated depending upon the degree of pain and swelling.

Seven to 10 days following the injury, patients are re-evaluated, including repeat weight-bearing radiographs to confirm alignment. If the isolated and stable nature of the injury is confirmed by examination and radiograph, the patient can be placed in an ankle brace or walking boot as symptoms allow [23].

Patients remain in the ankle brace or boot, with weight-bearing as tolerated, for four to six weeks. Radiographs are repeated four weeks after the injury and subsequently every two weeks until the fracture is clinically healed (ie, nontender over the fracture site with radiographic evidence of adequate callus around the fracture). Once clinically healed, patients should begin a gentle rehabilitation program.

Lateral malleolar fractures with deltoid ligament injury — A lateral malleolar fracture with disruption of the deltoid ligament is unstable and is managed no differently than a bimalleolar fracture (image 10). (See 'Determining stability of isolated lateral malleolus fractures' above.)

The instability associated with these injuries has been confirmed in outcome studies and cadaveric research models [8]. Anatomic reduction of the ankle with surgical stabilization leads to better clinical results [8]. Patients with this injury should be splinted with the ankle joint at 90 degrees and referred to an orthopedic surgeon within a few days. (See 'Indications for orthopedic consultation or referral' above.)

Bimalleolar and trimalleolar fractures — These fractures are unstable and require operative fixation. There is some evidence that a nondisplaced medial malleolar fracture may not require surgical repair if the fibular fracture is repaired [36]. Patients requiring surgery should be splinted with the ankle joint at 90 degrees, remain non-weight-bearing, and be referred to an orthopedist within a few days (image 9 and image 19). (See 'Indications for orthopedic consultation or referral' above.)

REHABILITATION AFTER ANKLE FRACTURE — 

The goal of rehabilitation after an ankle fracture is to restore any loss of motion, strength, or proprioception that may have occurred as a result of the injury or the subsequent immobilization and disuse related to treatment. There is little evidence that any specific rehabilitation program improves clinical outcomes [10]. It is possible that individuals may regain function and return to their preinjury level of activity more quickly with early rehabilitation [37].

Research about early weight-bearing and physical therapy is ongoing. For most patients embarking on a rehabilitation program, weight-bearing as tolerated in a walking boot is reasonable. Ambulating despite mild pain (<3 on a scale of 1 to 10) is acceptable, but weight-bearing should be avoided and medical evaluation sought if there is more significant pain.

For most ankle fractures, rehabilitation can be carried out with a basic home exercise program of stretching, range of motion, strengthening, and balance exercises [38]. A systematic review of 53 controlled trials related to the rehabilitation of ankle fractures noted a significant risk for bias and reported the following main findings [37]:

●Early weight-bearing – There is moderate-certainty evidence that early weight-bearing (within three weeks of surgery) leads to improved ankle function (mean difference [MD] 3.56, 95% CI 1.35-5.78; 5 studies, 890 participants), but the clinical significance of this improvement is unclear.

●Physical therapy interventions – A wide range of interventions have been evaluated, including active controlled motion, spring-loaded ankle trainer, enhanced stretching, manual therapy, joint mobilization, and neuromuscular exercises, but studies of such interventions vary in design and comparators, and most include few participants. Thus, the evidence is of low certainty, and it is difficult to draw meaningful conclusions.

●Removable versus nonremovable ankle support – Low-certainty evidence suggests that there may be no clinically significant difference between treatment with a removable and nonremovable ankle support (MD 6.39, 95% CI 1.69-11.09; 6 studies, 677 participants).

COMPLICATIONS — 

Ankle fractures have a relatively low complication rate when managed appropriately in patients without comorbidities. Complication rates in patients with significant comorbidities (eg, diabetes or peripheral vascular disease) or behaviors known to impair fracture healing (eg, smoking) are higher [39,40]. (See 'Indications for orthopedic consultation or referral' above and 'Treatment' above and "General principles of fracture management: Early and late complications".)

Acute complications — Acute complications of ankle fractures, such as injuries to peripheral nerves or vascular structures, open fractures, and compartment syndrome, are readily identified in most cases and require immediate surgical consultation. Rarely, nerve injury can occur at the time of injury from lacerations caused by fracture fragments or traction but may also occur during subsequent treatment from casting or splinting materials that compress the nerve [41]. Injuries to the lateral ankle or pressure on the proximal fibula from a cast or splint may lead to peroneal nerve injury causing weak foot dorsiflexion; injuries to the medial ankle may lead to tibial nerve injury. (See "Overview of lower extremity peripheral nerve syndromes", section on 'Fibular (peroneal) nerve' and "Overview of lower extremity peripheral nerve syndromes", section on 'Tibial nerve'.)

Lower extremity compartment syndrome is less likely to occur from ankle fractures than from fractures of the diaphysis of the tibia or fibula. Nevertheless, any patient complaining of increasing pain or new numbness and tingling or other symptoms concerning for compartment syndrome during treatment for an ankle injury should be examined without delay. (See "Acute compartment syndrome of the extremities", section on 'Clinical features'.)

Venous thromboembolism (VTE) is an infrequent complication, particularly of fractures managed nonoperatively, but occurs more often in older adults and patients with a history of VTE [42]. In an observational study of over 86,000 patients with ankle fractures requiring immobilization, VTE occurred in 1.3 percent of patients within 90 days. While low, this rate was approximately sixfold greater than among matched patients with hand wounds and wrist fractures.

Occasionally, skin damage can occur from stretching or abrasions incurred at the time of injury or from subsequent splinting and casting. Blisters and abrasions should be followed closely until they heal because of the risk of cellulitis [41].

Diabetics, older adults, and other high-risk populations — Diabetic patients have an increased risk of complications after ankle fracture [8,39]. Skin injury, postoperative infection, and malunion occur more frequently in diabetics. We suggest more frequent clinic visits (every two to three weeks), including careful skin examination and radiographs, for these patients.

According to retrospective reviews, older adult patients generally have more complex fracture patterns when compared with those under 65 years of age and are more prone to postoperative complications [43,44]. However, overall functional outcomes among patients above and below 65 years are similar when baseline function and the complexity of the fracture are taken into account.

Chronic complications — Potential chronic complications of ankle fractures include instability, osteoarthritis, and pain. Failure to recognize a syndesmotic injury that accompanies a fibular fracture above the ankle joint may lead to instability and premature osteoarthritis (image 20). In addition, a missed medial ligament injury in the setting of a lateral malleolar fracture can lead to instability, which can progress to joint pain and degeneration of the articular surface. While less than 5 percent of patients with unimalleolar fractures develop degenerative changes, detectable several years later by radiograph, as many as 20 percent of patients with bimalleolar fractures develop such radiographic findings [10].

Nonunion or malunion of ankle fractures is uncommon in healthy patients. Nevertheless, orthopedic referral is generally needed if a fracture does not appear to be healing as expected by eight weeks following the injury. Inadequate healing is suggested by persistent or worsening pain or tenderness at the fracture site or by signs of inadequate healing on plain radiographs. Orthopedic referral is necessary if the fracture displaces during the course of treatment.

If functional deficits (eg, restricted motion) persist despite appropriate management and rehabilitation, re-evaluation for associated injuries, such as ligament or tendon disruption, or osteochondral injury, should be performed. Orthopedic consultation or imaging with MRI may be needed in such cases.

Complex regional pain syndrome (CRPS) may develop in the days or weeks following an ankle fracture. Pain from CRPS is more severe than that expected from the inciting injury and is often associated with such findings as abnormal skin color, temperature change, diminished motor function, and edema (picture 5 and picture 6). Early identification and treatment of CRPS are important. (See "Complex regional pain syndrome in adults: Pathogenesis, clinical manifestations, and diagnosis", section on 'Clinical manifestations'.)

ADDITIONAL INFORMATION — 

Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:

●(See "General principles of fracture management: Bone healing and fracture description".)

●(See "General principles of fracture management: Fracture patterns and description in children".)

●(See "General principles of acute fracture management".)

●(See "General principles of definitive fracture management".)

●(See "General principles of fracture management: Early and late complications".)

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Lower extremity (excluding hip) fractures in adults" and "Society guideline links: Acute pain management".)

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics – (see "Patient education: Ankle fracture (The Basics)" and "Patient education: Fractures in adults (The Basics)" and "Patient education: How to care for your cast (The Basics)" and "Patient education: How to use crutches (The Basics)")

●Beyond the Basics topic – (see "Patient education: Cast and splint care (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Epidemiology and mechanism – The great majority of ankle fractures are malleolar fractures; 60 to 70 percent are unimalleolar. Supination (inversion) injuries typically cause distraction (stretching) of the lateral ankle structures and compression of the medial structures. Pronation (eversion) injuries cause medial distraction and lateral compression. Structures being distracted generally fracture or tear before structures being compressed. (See 'Epidemiology and risk factors' above and 'Clinical anatomy' above and 'Mechanism of injury' above.)

●Indications for referral – Open fractures and any injury with associated neurologic or vascular deficits require immediate orthopedic referral. Fracture dislocations require rapid reduction and referral. Loss of joint congruency or loss of stability are the major reasons for referral and surgical repair. Unstable injuries should be referred within a few days of injury. (See 'Indications for orthopedic consultation or referral' above.)

●Physical examination – Ankle fractures, particularly ones sustained in a fall, may mask other injuries. Especially with cases involving older adults or significant trauma, be sure to palpate the lumbar spine, hip, tibia, fibula (especially the fibular neck), and foot to check for associated injuries. (See 'Clinical presentation and examination' above.)

●Stable versus unstable injury – Once emergency conditions have been ruled out, the first priority is to determine whether the fracture is stable and can be managed nonoperatively or unstable and must be referred. Typically, an ankle fracture is stable if it meets the following criteria:

•It is isolated to the lateral (algorithm 1), medial, or posterior malleolus.

•It is nondisplaced and at or below the level of the mortise.

•It is not associated with a ligamentous injury.

An ankle fracture is unstable if two or more sites of significant injury are present, such as a lateral malleolar fracture with deltoid ligament disruption or a bimalleolar fracture. (See 'Clinical presentation and examination' above and 'Indications for orthopedic consultation or referral' above.)

●Diagnostic imaging – The Ottawa Ankle Rules help to determine whether radiographs of the ankle or foot are needed in the evaluation of an acute ankle injury (figure 18). Anterior-posterior (AP), oblique, and lateral radiographs are the standard views obtained if imaging is necessary. (See 'Diagnostic imaging' above.)

●Initial care – Initial management of ankle fractures consists of splinting, ice, elevation above the level of the heart, and analgesics. The ankle should be splinted at 90 degrees. Usually, a short-leg posterior splint is sufficient. (See 'Initial treatment' above.)

●Management – Unstable ankle fractures often require surgical repair. Management of the major types of ankle fractures is discussed in the text. The goal of rehabilitation is to restore any loss of motion, strength, or proprioception that may have occurred. (See 'Management of specific malleolar fractures' above and 'Rehabilitation after ankle fracture' above.)