INTRODUCTION — Fibular fractures, particularly those involving the ankle and the shaft just proximal, are common. They often result from minor trauma. Initial management is often provided by primary care and emergency clinicians, who must therefore be familiar with these injuries.
The diagnosis and management of fibular fractures is discussed here. Ankle fractures and sprains, stress fractures of the fibula, and fibula fractures in children are reviewed separately. (See "Ankle fractures in adults" and "Ankle sprain in adults: Evaluation and diagnosis" and "Stress fractures of the tibia and fibula" and "Tibial and fibular shaft fractures in children" and "Ankle fractures in children".)
EPIDEMIOLOGY AND RISK FACTORS — Fibular fractures in adults are typically due to trauma. Isolated fibular fractures comprise the majority of ankle fractures in older women, occurring in approximately 1 to 2 of every 1000 White women each year . Fibular fractures may also occur as the result of repetitive loading and in this case they are referred to as stress fractures.
In older adults, the key risk factor for fractures of the fibular or tibial shaft appears to be bone mass. Factors that reduce bone mass had greater impact than overall health status or other risk factors for falling. While not considered a "classic" osteoporotic fracture, clinicians should consider screening for osteoporosis when a fibular fracture occurs in the setting of unexpected weight loss, significant sarcopenia, poor diet, or a strong family history of osteoporosis  (see "Screening for osteoporosis in postmenopausal women and men" and "Osteoporotic fracture risk assessment"). Case reports describe fibular fractures associated with prolonged bisphosphonate treatment . (See "Risks of bisphosphonate therapy in patients with osteoporosis".)
Most studies show that women experience the greatest number of fibular fractures among older adults . However, one prospective study found no gender difference among patients with fibular fractures near the ankle . Cigarette smoking is another important risk factor for fibular fractures .
Athletes engaged in sports that involve cutting, particularly those associated with contact or collision, have a higher incidence of fibular fractures . Typical examples include American football, soccer, and rugby. In youth soccer, approximately 54 percent of fibula fractures occur with contact and 46 percent without .
Participants in downhill winter sports have relatively high rates of fibular fractures. These are more common in snowboarding than skiing, and fracture patterns are different for each. Skiers often fracture the proximal third of the tibia and also the fibula, whereas snowboarders are more likely to sustain isolated fractures of the distal third of the fibula .
Lateral ankle sprains that result from forced inversion of the foot cause lateral ankle pain and swelling that may be difficult to distinguish clinically from a distal fibular fracture. Thus, a fibular fracture should be suspected whenever there are clinical findings suggestive of ankle sprain. The approach to the patient with ankle pain due to an injury, including guidelines for obtaining radiographs, is presented separately. (See "Ankle sprain in adults: Evaluation and diagnosis".)
Major trauma and crush injuries can cause fibular fractures, but in such cases, the clinician should expect concomitant injuries of the tibia, neurovascular structures, the ligamentous attachment between tibia and fibula (tibiofibular syndesmosis), knee, and ankle joints. Injuries to these structures may have greater significance than any fibular injury. Tibial plateau fractures are associated with a proximal fibular fracture in approximately 60 percent of cases .
Rarely, complex injury mechanisms that stress the lateral collateral ligament of the knee can result in an avulsion fracture of the fibular head .
Fractures of the tibia and fibula sometimes occur together. These injuries are generally unstable and require urgent orthopedic consultation and operative intervention. (See "Overview of tibial fractures in adults" and 'Indications for orthopedic referral' below.)
CLINICAL ANATOMY — The fibula is a non-weight bearing bone that originates just below the lateral tibial plateau and extends distally to form the lateral malleolus, which is the portion of the fibula distal to the superior articular surface of the talus (talar dome) (figure 1 and figure 2). The lateral malleolus provides key stability against excessive eversion of the ankle and foot. Proximally, the fibular head is the site of attachment of the lateral collateral ligament of the knee (figure 3) and of the tendon from the biceps femoris (figure 4). Just below the fibular head, the common peroneal nerve wraps around the fibular neck before dividing at the proximal fibula into deep and superficial branches (figure 5).
Along the upper and middle lateral border of the fibula, the fibularis (peroneus) longus and brevis muscles originate and provide some soft tissue protection to the fibula from direct contusion (figure 6). The fibularis (peroneus) tertius and quartus, two lesser known muscles, contribute to fibular stability in some cases . Up to 22 percent of individuals have a fibularis tertius muscle, which arises from the distal one-third of the anterior fibula, has attachments on the intermuscular septum, and inserts onto the base of the fifth metatarsal. The fibularis quartus is present in approximately 7 percent of individuals. It arises from the distal half of the fibularis brevis muscle and may add some support for the lower third of the fibula and the lateral malleolus.
Multiple leg muscles originate from the fibular shaft, including muscles of the anterior compartment (extensor digitorum longus, extensor hallucis longus, fibularis tertius) (picture 1), the lateral compartment (fibularis longus, fibularis brevis) (picture 2), the superficial posterior compartment (soleus) (figure 7), and the deep posterior compartment (tibialis posterior (picture 3), flexor hallucis longus (picture 4)). The triangular shape of the fibular shaft allows insertion points for these multiple muscles .
The fibrous attachment between the tibia and fibula, the tibiofibular syndesmosis, prevents displacement of the lateral malleolus and diastasis between the tibia and fibula (figure 8). The distal portion of the syndesmosis has thickened fibers to form the distal tibio-fibular ligament (figure 9). Stability of this ligament allows the ankle to remain stable with external rotation during normal gait. Disruption of the syndesmosis (syndesmotic or high ankle sprain) contributes to instability of the tibiotalar joint.
MECHANISM OF INJURY — Most fibular fractures occur from inversion or twisting injuries or from direct blows to the lateral leg. A twisting fall with the foot planted imparts a rotary force that commonly leads to a spiral fibular fracture. Direct blows typically cause transverse fractures at the site at which the force is applied. Other mechanisms of injury include the following:
●Older adult patients, particularly those with an unsteady gait, may fall directly onto the lateral leg. If they have osteopenia this can result in a comminuted fibular fracture (image 1).
●Powerful stress applied to the lateral leg at the level of the knee can create a compressive force along the length of the bone. The resulting fracture may be remote from the site of the initial stress.
●Inversion injuries may cause a fibular fracture instead of a lateral ankle sprain (image 2).
●High-energy mechanisms, such as motor vehicle accidents, can lead to severely comminuted or crush injuries of the fibula .
CLINICAL PRESENTATION AND EXAMINATION — Clinical presentation of a fibula fracture will vary depending on the patient, mechanism, and extent of injury. The patient with a minor fracture sustained through an ankle inversion or eversion strain may be ambulating and complain only of lateral ankle pain, while the presence of a fracture in a pedestrian struck by a vehicle is generally obvious.
The lower extremity should be examined systematically. The injured leg is examined for shortening and angulation. The skin is inspected for evidence of one or more of the following:
●Contusion or discoloration
●Puncture wounds or evidence of secondary infection
●Protrusion of bone fragments indicative of an open fracture
If medicolegal considerations warrant and time permits, photographs of the injury may be taken with the patient's permission. Wound and blood cultures should be obtained prior to initiating antibiotic therapy if there are signs of soft tissue infection.
With uncomplicated fibular fractures, individuals often can ambulate but have increasing pain when doing so. Tenderness and swelling along the shaft of the bone may suggest the location of the fracture.
Careful assessment of neurovascular status, ankle plantar- and dorsiflexion, peroneal muscle function, and the degree of swelling in the lateral compartment is necessary to detect complications, including acute compartment syndrome, which can arise from bleeding or edema in the lateral compartment. (See "Acute compartment syndrome of the extremities" and "General principles of fracture management: Early and late complications".)
Examination of the knee and ankle joints and inspection and palpation along the length of the tibia are necessary because fibular fractures may occur in conjunction with injuries to these structures. Examination of the ankle may reveal a coexisting medial malleolar fracture, deltoid ligament injury, or separation of the distal tibiofibular syndesmosis. This last injury is sometimes associated with a concomitant Maisonneuve fracture of the proximal fibula. Significant force applied to the medial knee (varus stress) may fracture the fibular head, or possibly cause an intraarticular knee injury or lateral collateral ligament tear or avulsion fracture. (See "Physical examination of the knee" and "Ankle sprain in adults: Evaluation and diagnosis", section on 'Physical examination'.)
The lateral drawer test may be useful for detecting instability associated with a fibula fracture but requires further study and validation .
Plain radiographs and initial approach to imaging — Standard anteroposterior (AP) and lateral plain radiographs of the entire lower leg generally are sufficient to demonstrate a fibular fracture, and these should be obtained whenever a fibular fracture is suspected based upon the mechanism of injury or clinical findings (image 4A-B and image 5).
If there is ankle pain, a full ankle series (AP, lateral, and mortise view (image 6)) is also obtained. Widening of the space between the medial malleolus and the talus (a talar shift) suggests disruption of the syndesmosis (image 7). If a talar shift is noted, a proximal fibular fracture may also be present, and radiographs of the proximal fibula should be carefully inspected for evidence of a Maisonneuve fracture (image 8 and image 3).
If there is uncertainty about the stability of the ankle, stress views can be obtained. These may help to identify subtle medial widening indicative of a syndesmotic tear (image 9). Soft tissue ecchymosis, swelling, or medial tenderness is not a good predictor of deltoid ligament injury when compared to stress radiographs and should not be used as clinical indications for surgery . (See "Ankle fractures in adults".)
Stress views of isolated fibular fractures are positive in the majority of patients. However, these should not be interpreted as requiring surgical fixation unless clinical findings also suggest medial ankle injury. In one prospective study, 20 patients with positive stress views but no clinical evidence of medial ankle injury were treated nonoperatively, and all had good to excellent outcomes .
When a tibial plateau fracture is diagnosed, standard radiographs show an associated proximal fibular fracture in 54 percent of cases . When computed tomography (CT) is used, the rate increases to 60 percent.
Classification schemes — Orthopedists use classification schemes to describe fibula fractures. The most common are the Lauge-Hausen system, which classifies fractures according to radiographic appearance and mechanism of injury, and the Danis-Weber system, which classifies fractures based upon the location and appearance of the fibular injury. Neither classification system appears to correlate closely with outcomes, but they are used by surgeons to designate injury patterns .
Musculoskeletal ultrasound — Examination using high resolution musculoskeletal ultrasound probes can be useful for identifying fibular fractures at the bedside in the emergency department, office, and special settings, such as ski resort clinics (image 10) . With minor trauma, ultrasound may adequately identify the extent of injury and guide treatment.
In an observational emergency department study of patients with foot and ankle trauma, ultrasound identified all 20 of the lateral malleolus fractures found on subsequent radiographs . However, ultrasound cannot provide a complete view of the fibula, so definitive diagnosis using standard radiographs remains necessary in many cases, particularly trauma involving significant force.
Advanced imaging — In special situations magnetic resonance imaging (MRI) or computed tomography (CT) imaging may be needed for fibular fractures. CT scan may be indicated to characterize a posterior tibial plafond fracture, which is often associated with a fibular fracture. MRI can help determine the degree of soft tissue damage from crush injuries or other major trauma. MRI or CT may also help when fractures appear to be associated with underlying pathology, such as an intrinsic bone disease or malignancy.
DIAGNOSIS — The diagnosis of fibula fracture is made by diagnostic imaging. In the large majority of cases, plain radiographs are sufficient. Additional views or more advanced techniques (eg, CT) may be needed to delineate concomitant injuries.
DIFFERENTIAL DIAGNOSIS — For fractures of the distal fibula, the most common alternative diagnosis is ankle sprain. The two diagnoses are distinguished on the basis of physical examination (eg, presence of bony deformity) and imaging studies. (See "Ankle sprain in adults: Evaluation and diagnosis".)
During sport, motor vehicle collisions, and other trauma, blunt force directed at the leg may cause bone or soft tissue contusions over the fibula. Acute compartment syndrome of the lateral leg compartment causes pain along the region of the fibular shaft, and may be confused with fracture in rare situations. Normal radiographs exclude fracture in these cases. (See "Acute compartment syndrome of the extremities".)
Low-energy trauma can cause a range of injuries in the regions of the knee, leg, and ankle. The differential diagnoses following such trauma are reviewed separately:
●For the differential diagnosis for trauma-related leg pain. (See "Tibial shaft fractures in adults", section on 'Differential diagnosis'.)
●For the differential diagnosis for trauma-related lateral knee pain. (See "Lateral collateral ligament injury and related posterolateral corner injuries of the knee", section on 'Differential diagnosis'.)
High syndesmosis injury may cause pain over fibular head. Peroneal (fibularis) tendon tears may cause pain directly along the fibular shaft.
Rarely, tumors that primarily occur in the proximal fibula can mimic fracture . The presenting complaint is usually pain, which may increase after minor trauma. The most common such tumor is osteochondroma.
INDICATIONS FOR ORTHOPEDIC REFERRAL — Significant crush injuries, open fractures, fractures of the fibula with an associated tibial fracture, and fractures in which a lateral compartment syndrome or peroneal nerve injury are suspected all require immediate evaluation by an orthopedic surgeon.
Displaced fractures, in which there is any significant overlap of fragments, shortening, or angulation; and comminuted fractures (image 1) warrant timely orthopedic consultation, ideally no more than 48 to 72 hours after the injury. Patients not seen by an orthopedist initially need clear instructions about symptoms that suggest a developing compartment syndrome or deep venous thrombosis. Those symptoms warrant immediate return to the emergency department.
Distal fibular fractures extending into the ankle joint (intra-articular), particularly when associated with a deltoid ligament injury, may result in an unstable ankle. Such injuries involving both the medial and lateral ankle often merit additional imaging, to include weightbearing radiographs or computed tomography (CT), and orthopedic referral [23,24]. (See "Ankle fractures in adults".)
Spiral fractures arise from a pronation and external rotation mechanism and often involve syndesmosis tears. These may not remain reduced without surgical stabilization and merit orthopedic consultation or close follow-up with repeat radiographs for those treated conservatively. When the injury appears to involve the knee or ankle joint as well as the lateral leg, orthopedic assessment of the joint takes priority over the fibular injury. Complex and comminuted fibular fractures require surgical stabilization (usually with a plate, double plating technique, or intramedullary nail). Ongoing research is helping to define which patients benefit from specific surgical approaches [5,15].
Pilon (hammer) fractures arise when a forceful axial load drives the talus into the distal tibia leading to a comminuted distal tibia fracture (image 11). Approximately 75 to 85 percent have associated fibular fractures. These require immediate orthopedic consultation.
Fractures of the proximal fibular head or neck (Maisonneuve fractures (image 3 and image 8)) are frequently unstable due to tears in the syndesmotic ligament complex (ie, tibio-fibular ligament). Referral to an orthopedic surgeon is indicated if radiographs reveal a shift of the talus or other evidence of associated deltoid ligament disruption. While nondisplaced fractures with minimal joint widening seen on the mortise view are occasionally treated with conservative care, Maisonneuve injuries often require operative management.
Observational evidence suggests that surgical intervention for unstable or complicated fibula fractures produces good outcomes. While plate fixation has been a standard approach, studies of intramedullary nailing suggest comparable outcomes for most fractures .
Orthopedic consultation is prudent, even for fractures that appear uncomplicated, when symptoms extend beyond the time normally required for healing (approximately 8 to 12 weeks). In a randomized trial of acute fibular fractures, patients who underwent arthroscopy assisted diagnosis and treatment were found to have osteochondral lesions of the talus and syndesmotic tears in the majority of cases . Such concomitant injuries may not be apparent on initial assessment, but can contribute to unsatisfactory treatment outcomes.
When patients do not demonstrate normal healing of a fracture that appears uncomplicated, additional review of the medical history may identify overlooked factors. Diabetes, obesity, peripheral neuropathy, other chronic illnesses, and even use of certain medications, such as isotretinoin, can contribute to delayed healing .
INITIAL TREATMENT — Basic general care for acute fractures is described separately. (See "General principles of acute fracture management" and "General principles of definitive fracture management".)
For most distal fibular injuries, initial immobilization is achieved with a molded stirrup splint of plaster or fiberglass (figure 10), or with a prefabricated air-cushioned or other padded splint that applies compression and protection from varus or valgus stress (picture 5). In some cases, the air-splint is sufficient for definitive treatment. (See "Basic techniques for splinting of musculoskeletal injuries" and "Patient education: Cast and splint care (Beyond the Basics)".)
Fractures of the fibular head and neck are often associated with an injury to the tibia or knee joint, or may involve displacement of the fibular head. If careful assessment reveals no significant concomitant injury, no displacement, and no injury to the peroneal nerve, treatment with immobilization is reasonable. For patients with such complications, who should be referred for evaluation by an orthopedic surgeon, initial immobilization in a long leg knee immobilizer in near-full extension is appropriate.
Crutches for non-weight bearing ambulation are needed for more painful or severe injuries. However, even with more severe injuries, early partial weight bearing is low risk in younger patients since the fibula is not a primary weight bearing structure. Icing, elevation, mild compression, and analgesics all are adjunctive treatments. In older patients, particularly those with an unstable gait, initial weight bearing is inadvisable for any but very minor fractures, and progress to weight bearing may be slow.
Prolonged icing of the proximal fibula near the fibular head may cause injury to the common peroneal nerve. Case reports describe foot drop and delayed recovery in such cases .
FOLLOW-UP CARE — For distal fibular fractures, after two to three days, the stirrup splint can be exchanged for a prefabricated walking cast appliance, long air stirrup splint, or short leg cast. A short leg cast is used if the patient is not comfortable ambulating in a prefabricated padded splint. Symptoms guide the choice of treatment with most fractures. The patient should have adequate pain relief and be able to ambulate well in whatever cast or splint is chosen. Minor fractures sometimes require no splinting and only a few days of crutch walking. Some athletes do well with compression wraps and taping alone.
Most individuals continue to use some type of immobilization for three to four weeks and then increase their activity based on symptoms. The patient with an uncomplicated fibular fracture returns for assessment at three to four weeks from initial treatment. More frequent follow-up visits are the norm for complicated fractures.
Definitive care of uncomplicated, isolated proximal fibular fractures consists of a long leg cast or brace-immobilizer with the knee in near-full extension (ie, slight knee flexion).
When radiographs reveal callus formation and filling in of the fracture line, most patients can begin the process of converting from continuous cast or splint use to use of a splint only when needed for protection during exercise and for comfort. For clinicians experienced with diagnostic ultrasound (US), an alternative approach for uncomplicated fractures is to use US to follow callous formation to help guide the patient’s return to activity. Peroneal muscle strengthening and ankle range of motion exercises begin with the individual out of splint once there is evidence of healing on the radiographs. Healing in adults is typically complete by six to eight weeks.
RETURN TO WORK OR SPORT — Fibular fractures occasionally place significant limitations on return to work. For individuals with jobs requiring prolonged standing or walking, accumulated swelling during work may be quite severe for the first few weeks after the injury. This may necessitate periods of rest to allow for elevation of the limb and reduction of swelling. Most employees return to work in the first week or within a week while wearing a stirrup splint.
While many athletes and laborers with minor fibular fractures may return to activity in as little as four to six weeks, more complex injuries require substantially longer. Proximal, distal, and complex fractures that require surgery require four months or longer for adequate healing.
For athletes with minor injuries, splinting continues for three to four weeks followed by a few weeks of rehabilitation. Training resumes at six weeks and full training usually starts at approximately eight weeks. When the fracture is minor, the pace of the rehabilitation schedule can be increased based primarily on pain tolerance. After the first week of splinting, many athletes can run or train at reduced intensity while wearing a light-weight stirrup. Exceptions to this rapid return to sport include sports like soccer in which the lower leg is subjected to high torsional stresses and direct trauma. According to a retrospective review, soccer athletes with isolated fibular fractures required 18 weeks to return to competition . Refracture complicated efforts to return too quickly to contact sports in a case series .
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:
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 5th to 6th 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 10th to 12th 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 topic (see "Patient education: How to care for your cast (The Basics)" and "Patient education: How to care for your child's 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
●Anatomy, epidemiology, and mechanism – The fibula is a non-weight bearing bone, and in the absence of any complications or concomitant tibial, knee, or ankle injury, fibula fractures can often be managed successfully nonoperatively.
Fibular fractures can be caused by forces applied directly to the fibula or indirectly through stress on the knee or ankle. Injuries to the knee or ankle are potentially more disabling than the fibula fracture itself. (See 'Mechanism of injury' above.)
●Imaging – Plain radiographs of the entire lower leg including AP and lateral views are sufficient to diagnose most fibula fractures. Knee or ankle radiographs are needed if there is suspicion of injury to either joint. Ultrasound can be used as a rapid screening technique to identify fibular fractures in the emergency department, office, or remote clinics. (See 'Diagnostic imaging' above.)
●Associated syndesmotic injury – Widening of the tibiotalar joint space suggests the presence of a rupture of the tibiofibular syndesmosis and the possibility of a Maisonneuve fracture (proximal fibular fracture following ankle injury (image 3)). These injuries are often unstable due to ligamentous disruption and orthopedic referral is necessary.
●Differential diagnosis – The differential diagnosis for fibula fracture is broad. Distal injuries may be mistaken for an ankle sprain. Plain radiographs can be used to rule out fracture in most instances. (See 'Differential diagnosis' above.)
●Indications for referral – Fractures involving both the fibula and the tibia are inherently unstable and require urgent orthopedic consultation or immobilization and referral. Severe crush injuries, open fractures, badly displaced spiral fractures, and fractures associated with neurovascular deficits or suspected compartment syndrome require emergency (ie, immediate) orthopedic referral. (See 'Indications for orthopedic referral' above.)
●Management – Initial management of isolated, non-displaced fibular fractures includes immobilization with a splint, analgesics, ice, and elevation of the limb to control pain and swelling. Non-weight bearing with crutches may be needed for painful or severe fibular fractures. (See 'Initial treatment' above.)
With distal fibula fractures, after two to three days the splint can be exchanged for a short leg “cam walker” or standard walking cast or the stirrup splint may be used for the entire period of immobilization, a period of from three to four weeks.
Fractures of the proximal fibula often are associated with injuries to the tibia, syndesmosis, knee joint, medial ankle, and peroneal nerve. Fractures associated with such complications should be referred to an orthopedic surgeon. Nondisplaced fractures without associated injuries can be treated with a long leg cast or a brace-immobilizer.
●When radiographic healing is apparent and pain permits, rehabilitation may begin. Complete healing of isolated, non-displaced fibular fractures in adults typically takes from six to eight weeks. (See 'Follow-up care' above and 'Return to work or sport' above.)
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