Non-stress fractures of the tarsal (foot) navicular

INTRODUCTION — Midfoot injuries are relatively uncommon, but the majority involve a combination of fractures and ligament injuries. The tarsal navicular bone is the keystone of the medial column of the foot, bearing the majority of the load applied to the tarsal complex during weight-bearing [1]. Acute fractures of the tarsal navicular are uncommon, and isolated fractures are even more uncommon, as tarsal navicular injury is typically associated with other fractures, dislocations, or soft tissue injuries of the foot.

The presentation, diagnosis, and management of acute tarsal navicular fractures is reviewed here. Stress fractures of the navicular are discussed separately as are other foot and lower extremity injuries. (See "Stress fractures of the tarsal (foot) navicular" and "Tarsometatarsal (Lisfranc) joint complex injuries" and "Metatarsal shaft fractures" and "Proximal fifth metatarsal fractures" and "Talus fractures" and "Calcaneus fractures" and "Overview of foot anatomy and biomechanics and assessment of foot pain in adults" and "Fibula fractures" and "Ankle fractures in adults".)

EPIDEMIOLOGY — Midfoot injuries comprise approximately 5 percent of all foot injuries [2-4]. The majority of midfoot injuries are combined injuries stemming from high-energy trauma and involve both osseous and ligamentous structures. Typically, midfoot injuries involve multiple fractures or fracture dislocations. Up to 30 percent of midfoot injuries are missed primarily or treated in a delayed manner, and these have poorer outcomes compared to injuries identified early and managed appropriately [5].

Navicular fractures are frequently associated with other fractures, dislocations, or ligament injuries and may result in considerable long-term disability. Stress fractures of the navicular are more common, comprising 14 percent of all stress fractures [6,7].

CLINICAL ANATOMY — Foot anatomy is reviewed in detail separately; aspects of foot anatomy, with particular relevance to navicular fractures, are discussed below. (See "Overview of foot anatomy and biomechanics and assessment of foot pain in adults", section on 'Anatomy and biomechanics'.)

Midfoot injuries are relatively uncommon, primarily due to strong ligamentous connections among the five bones that form the mid-tarsal complex (navicular, cuboid, and cuneiforms) (figure 1 and figure 2). The navicular acts as a keystone for the medial column and longitudinal arch of the foot. It articulates with the talus proximally, the cuboid laterally, and the medial, intermediate, and lateral cuneiforms distally. Because of these multiple articulations, the majority of the navicular surface is covered with cartilage. The most important navicular articulation is posteriorly with the talus. This talonavicular joint is responsible for the majority of hindfoot motion [8].

Several ligaments unite the navicular with neighboring bones and several tendons insert on the navicular (figure 3). The most clinically important of the tendon attachments is the posterior tibialis tendon, which inserts on the navicular tuberosity. Other clinically significant attachments include the deltoid ligament and the plantar calcaneonavicular (spring) ligament, which originates at the sustentaculum tali of the calcaneus and inserts along the medial and plantar aspects of the navicular.

The navicular receives its blood supply from branches of the dorsalis pedis artery dorsally and branches of the tibialis posterior artery along the plantar and medial aspects. The convergence of these two networks results in a zone of poor blood supply (so-called "watershed" area) that predisposes this region to stress fractures and healing disturbances, which may increase the risk for non-union (figure 4).

MECHANISM OF INJURY — The clinical presentation of navicular fractures can vary widely. Typical lower energy mechanisms include twisting combined with either forced plantar flexion or forced dorsiflexion of the midfoot. High-energy trauma may involve a motor vehicle collision, sports-related collision, or a fall from a height. Usual mechanisms for each major type of navicular fracture are described below. (See "Stress fractures of the tarsal (foot) navicular", section on 'Management'.)

HISTORY AND EXAMINATION FINDINGS — Patients with acute fractures of the navicular usually present with severe pain over the dorsal or dorsomedial foot following trauma. They experience difficulty with weight-bearing, as well as increased pain and possibly an inability to walk on or push off (ie, plantarflex while weight-bearing) with their toes. There is typically localized swelling and tenderness over the navicular. Resisted eversion of the foot stretches the deltoid ligament and tibialis posterior tendon, and this elicits pain in patients with a tuberosity fracture of the navicular. Foot alignment should be examined for signs of dislocation (eg, bony step-off). Details of the presentation and examination findings associated with each major type of navicular fracture are described below. (See "Stress fractures of the tarsal (foot) navicular", section on 'Management'.)

DIAGNOSTIC IMAGING — The initial assessment of patients with a possible midfoot fracture, including the navicular, includes standard plain radiographs of the foot: anterior-posterior (AP), lateral, and oblique views (image 1). The AP view, in addition to providing an overall picture of bone length and alignment, is useful for visualizing tuberosity and body fractures (image 2 and image 3). The lateral view is best for viewing dorsal avulsion fractures and for supplementing the AP view in assessing the talonavicular and naviculocuneiform joints. Weight-bearing radiographs can be obtained to rule out unstable injuries of the midtarsal joint complex, and are much preferred for the initial evaluation of any midfoot injury (image 4) [9]. If possible, the radiographs should be taken with the patient bearing all their body weight on the foot being radiographed (ie, standing on one leg). In addition, the radiographs may be taken with the knee of the supporting leg flexed to 30 degrees, which places the foot in a more physiologic position [10]. Radiographs of the contralateral foot are often useful in determining the appropriate length, alignment, and shape of the navicular.

Of note, an accessory navicular bone is present in 4 to 21 percent of adults [8,11]. While these ossicles can occur in multiple configurations, accessory navicular bones (or accessory ossicles) have smooth, rounded borders, and occur bilaterally in nearly 70 percent of individuals (image 5 and figure 1). The accessory navicular is sometimes referred to as an os naviculare.

The sensitivity of plain radiographs for identifying acute navicular fractures is 33 percent when using computed tomography (CT) as the gold standard [12]. Therefore, if an acute navicular fracture is suspected clinically despite the absence of any obvious fracture on plain radiographs, CT imaging (image 6 and image 7) with multidimensional reconstruction is recommended. CT with reconstructions enables assessment of fracture patterns, dimensions, degree of comminution, displacement, articular involvement, and associated injuries, and assists with preoperative planning [9].

While CT is preferred for suspected acute fractures, magnetic resonance imaging (MRI) is preferred for detection and characterization of stress fractures or when distinguishing between acute bony fracture fragments and an atypical os naviculare. In both of these instances, the ability to see bone edema with MRI is helpful diagnostically and prognostically (image 8) [13].

GENERAL INDICATIONS FOR SURGICAL REFERRAL — Isolated acute fractures of the navicular are rare. In the majority of cases, acute navicular fractures are associated with other significant injuries, including bony dislocations, ligamentous tears, and tendinous avulsions [9,14]. Associated injuries may remain occult without advanced imaging [15]. Therefore, we recommend referral to a clinician with broad experience managing midfoot fractures, most often a foot and ankle surgeon, for most acute navicular injuries. These include all navicular fractures sustained from high-energy trauma (eg, motor vehicle crash), and any sustained from low-energy trauma that involve clinical signs suggesting associated injury (eg, marked swelling, slow healing, or delay in expected return to weight-bearing). The indications for surgical referral based on the type of fracture are described below. (See 'Presentation and management of major fracture types' below.)

DIFFERENTIAL DIAGNOSIS — Navicular fractures often result from major trauma involving the foot. Other significant bony and soft tissue injuries of the lower leg, ankle, hindfoot, midfoot, and forefoot can present in similar fashion. Plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) are needed to determine the overall extent of injury and to distinguish these injuries from one another. The differential diagnosis for patients presenting with midfoot pain in the region of the navicular without apparent major trauma is reviewed separately. (See "Evaluation, diagnosis, and select management of common causes of midfoot pain in adults", section on 'Medial arch (navicular) injury'.)

PRESENTATION AND MANAGEMENT OF MAJOR FRACTURE TYPES — The four basic types of navicular fracture include: dorsal avulsion, tuberosity, body, and stress fractures. Stress fractures are reviewed separately, but basic non-operative management of the remaining fractures is discussed below. (See "Stress fractures of the tarsal (foot) navicular".)

Dorsal avulsion fractures

●Mechanism and overview – Dorsal avulsion fractures of the navicular often occur as a result of trauma involving twisting or eversion of a plantar-flexed foot. These fractures can be associated with injuries to either the talonavicular or naviculocuneiform ligaments.

●Clinical features – Patients with dorsal avulsion fractures may be able to ambulate on the affected foot. There is often localized swelling and ecchymosis over the navicular, as well as tenderness, over the dorsal navicular region (picture 1).

●Imaging – Lateral radiographs generally reveal avulsion fractures along the dorsal aspect of the navicular (image 9 and image 10 and image 11). If an avulsion fracture is identified, weight-bearing films are required to rule out unstable injuries of the midtarsal complex. If weight-bearing films cannot be obtained due to discomfort, or clinical suspicion for more extensive injury is high due to extensive swelling or a high-energy mechanism, CT scan should be performed to determine the extent of injury.

●Indications for surgical referral – Avulsion fractures range from very small (image 9), to moderate sized (image 10), to large injuries involving a significant portion of the articular surface (image 11). Avulsion fracture healing depends on the extent of associated ligamentous injuries. Avulsion fractures without significant associated ligamentous injury heal well when treated with or without surgery. Avulsion fractures associated with severe ligament damage heal best when treated with anatomic surgical reduction and fixation [13,15].

Specific indications for surgery include:

•Dorsal avulsion fracture that involves more than 20 percent of the talonavicular articular surface

•Intra-articular fragmentation

•Avulsion fractures with marked, diffuse soft-tissue swelling

•Uncomplicated avulsion fracture with delay in return to weight-bearing past 10 weeks or persistent pain with weight-bearing past 12 weeks

Isolated avulsion body fractures that do not meet criteria for surgical referral may be managed non-operatively. However, even with apparently simple navicular fractures, concomitant injuries are common and non-surgeons must be certain that no such injury is present before assuming long-term care. When providing non-operative management of any acute navicular fracture, the initial cast should be removed and full weight-bearing radiographs repeated after two weeks to help ensure that no occult concomitant injury exists. Complications from missed navicular or associated injuries can result in severe, permanent disability [9]. If there is any doubt about the extent of injury, it is best to obtain advanced imaging or refer the patient to a surgical specialist.

●Management – Provided the dorsal avulsion fracture involves less than 20 percent of the talonavicular articular surface and there is a low clinical suspicion for more extensive injury, a trial of non-operative management is warranted. Fractures involving more than 20 percent of the joint surface should be referred to a surgical specialist [13,15]. The following radiograph provides an example (image 11).

Non-operative management for uncomplicated fractures initially consists of a short leg splint or a bulky dressing applied for 7 to 10 days to allow for swelling to subside. Basic care includes ice and elevation of the foot above heart level. Crutches are used during this timeframe when the patient is non-weight-bearing. Once swelling has subsided after 7 to 10 days, repeat weight-bearing radiographs are obtained to look for occult injury. If radiographs reveal no such injury, a walking fracture boot with good arch support or a short-leg walking cast with a well-molded arch is applied for an additional four to six weeks [13]. If there is evidence of delayed clinical healing (as demonstrated by localized pain with range of motion testing or persistent tenderness over the navicular at six weeks), or the patient is unable to bear weight without discomfort with the cast or boot off after eight weeks, repeat weight-bearing radiographs should be obtained. Advanced imaging with CT to determine the extent of injury or surgical referral is appropriate at this point [14,16].

If the injury is healing clinically, once the walking boot or weight-bearing cast is removed the patient should begin a graduated rehabilitation program that includes ankle and foot mobility and strength exercises.

●Return to work/sports – In general, patients with dorsal avulsion fractures return to full activity within two to three months [14]. This two to three month window allows for at least four weeks of immobilization followed by three to four weeks of rehabilitation and graded return to activity. Return to sport is determined by the patient's ability to perform sport-specific movements without significant pain or dysfunction. Those with sedentary jobs can return to work shortly after injury.

Tuberosity fractures

●Mechanism and overview – Tuberosity fractures of the navicular often occur as a result of a foot eversion injury that places stress on the tibialis posterior tendon and deltoid ligament [14].

●Clinical features – Patients typically present with painful ambulation or refusal to bear weight due to pain. There is often focal swelling and ecchymosis at the medial navicular, as well as tenderness over the tuberosity along the medial aspect of the navicular (picture 1). Passive or active eversion of the foot elicits pain.

●Imaging – AP and oblique view plain radiographs may be useful for assessing tuberosity fractures. However, the sensitivity of plain radiographs for identifying tuberosity fractures is limited, and CT imaging (image 7) should be obtained if there is any concern for a navicular fracture despite unremarkable plain films.

●Management – The non-operative management of tuberosity fractures is a matter of some debate among foot and ankle surgeons [15,17]. Classically, tuberosity fractures with less than 1 cm displacement can be managed non-operatively; fractures with greater displacement are referred to a surgical specialist. However, given the devastating consequences of traumatic insufficiency of the posterior tibialis tendon (progressive hindfoot valgus and disabling flat-foot deformity), we recommend that consultation or referral to a surgeon with experience managing tuberosity fractures be obtained for all such injuries, as many are treated surgically. Non-surgeons with experience managing midfoot fractures may choose to care for patients with uncomplicated, non-displaced navicular tuberosity fractures.

If non-operative care is appropriate (eg, isolated, non-displaced fracture), and elected by the patient, the injured foot is initially placed in a short leg splint or bulky dressing for no more than seven days to allow for swelling to subside. Standard initial care includes the application of ice and elevation of the foot above heart level to reduce pain and swelling. Crutches may be used if needed. Once swelling has subsided, a short-leg walking cast that is well molded along the longitudinal arch of the foot is applied and worn for four to six weeks [14].

Tuberosity fractures are at risk for non-union and repeat plain radiographs should be obtained once immobilization is complete to assess the presence of callus formation and radiographic healing. No standard criteria exist for radiographic determination of union versus non-union. With limited evidence, physicians therefore must rely on repeat imaging and physical examination to make this assessment [18]. If a symptomatic non-union is present at six weeks (eg, navicular remains tender and radiographs show no callus formation), the foot should be immobilized for an additional two to four weeks to achieve union. If this fails (ie, non-union persists), the primary care clinician should refer the patient to a surgical specialist [16].

Once healing is adequate and immobilization is no longer needed, patients should begin a deliberate, graduated rehabilitation program that includes ankle and foot mobility and strength exercises. Early mobility exercises are contraindicated due to the risk of non-union.

●Return to work/sports – In general, patients with tuberosity fractures return to full activity within two to three months [14]. This two to three month window allows for at least four weeks of immobilization followed by three to four weeks of rehabilitation and graded return to activity. Return to sport is determined by the patient's ability to perform sport-specific movements without significant pain or dysfunction. Those with sedentary jobs can return to work shortly after injury.

Body fractures

●Mechanism and overview – Body fractures of the navicular are caused by various mechanisms, including direct trauma, foot hyperextension, extreme foot flexion with rotation, and axial loads combined with plantar flexion and either adduction or abduction [9,14]. These fractures are often associated with other injuries of the midtarsal joint and careful assessment is required to avoid missed or delayed diagnoses of concomitant injury.

●Clinical features – Patients typically present with painful ambulation or refusal to bear weight due to pain. There is often diffuse swelling and ecchymosis, as well as tenderness diffusely, over the entire dorsomedial navicular (picture 1). Particularly following crush injuries, acute compartment syndrome can develop and clinicians must remain vigilant about monitoring such complications. (See "Acute compartment syndrome of the extremities".)

●Imaging – AP, lateral, and oblique plain radiographs generally provide adequate visualization of the navicular bone but their sensitivity for navicular body fractures is limited (image 12). In addition, navicular fractures are frequently associated with other fractures and soft tissue injuries. Thus, when an acute navicular fracture is suspected clinically, or when a navicular body fracture is identified on plain films, a CT scan should be obtained.

●Classification – Classification of acute navicular fractures is confounded by multiple proposed classification schemes, all using different anatomic patterns. The most commonly used scheme is that proposed by DeLee in 1986 [19], which categorizes acute navicular body fractures into three types (figure 5):

•Type I – Longitudinal fracture of dorsum involving less than 50 percent of the bone and no medial deformity

•Type II – Oblique fracture, typically running dorsal-lateral to plantar-medial (image 12)

•Type III – Fracture involving lateral or central comminution (image 8)

●Indications for surgical referral – Surgical referral should be obtained for the following injuries:

•Type I (longitudinal) body fractures with comminution, more than 2 mm of talonavicular displacement, or foreshortening of the navicular bone

•All type II (image 12) or type III (image 8) body fractures

•All fracture-dislocation injuries

Type I body fractures that do not meet criteria for surgical referral may be managed non-operatively. However, even with apparently simple navicular fractures, concomitant injuries are common, and non-surgeons must be certain that no such associated injury is present before assuming care. When attempting non-operative management of any acute navicular fracture, the initial cast should be removed and full weight-bearing radiographs repeated after two weeks to ensure no occult concomitant injury exists. Complications from missed navicular or associated injuries can result in severe, permanent disability [9]. If there is any doubt about the extent of injury, it is best to obtain advanced imaging or refer the patient to a surgical specialist.

●Management – Type I body fractures (longitudinal body fractures) with less than 2 mm displacement, no comminution, no foreshortening, and no subluxation or dislocation with weight-bearing may be appropriate for non-surgical management [20]. All other acute navicular fractures of the body should be referred to a surgical specialist.

In addition to standard care (rest, ice, elevation), initial treatment for appropriate type I body fractures consists of a well-molded, non-weight-bearing cast, bi-valved if necessary to allow for swelling during the acute phase. After 10 to 14 days, the cast is removed and weight-bearing, three-view radiographs are obtained to assess fracture stability and to help verify that no additional injuries are present. Once the fracture is determined to be stable and isolated, a non-weight-bearing, short leg cast is replaced and maintained for a total of six to eight weeks of non-weight-bearing immobilization [21].

Some authors recommend that radiographs be repeated every two weeks until there is radiographic evidence of healing [14], but as radiographic healing is difficult to detect and often lags behind clinical healing, our practice is to perform radiographs after the initial two weeks of treatment, and then use the absence of bony tenderness as the primary marker for bony healing.

After six to eight weeks of non-weight-bearing immobilization, patients are transitioned to a short-leg walking cast or a removable walking boot with well-padded arch support. Patients are only transitioned to weight-bearing immobilization when all bony tenderness has resolved, and they are able to bear full weight in a standing position without pain. If tenderness persists or the patient cannot bear weight without pain after 10 weeks of non-weight-bearing immobilization, we refer the patient to a surgeon and typically advanced imaging is performed (generally CT).

Once weight-bearing immobilization begins, patients are slowly transitioned to full weight-bearing status as follows: 25 percent weight-bearing with crutches for the first week, 50 percent for the second week, 75 percent for the third week, and full weight-bearing for the fourth week. Once they are able to bear full weight in the boot or walking cast for two consecutive weeks, the patient can transition to a well-supported walking shoe. Because of the risk for non-union and the likelihood of significant associated ligamentous injury, navicular body fractures are not appropriate for early mobilization protocols. We recommend that patients use a longitudinal arch support in their shoes for at least one year following injury.

●Return to work/sports – As navicular body fractures require longer immobilization than tuberosity or dorsal avulsion fractures, lengthier rehabilitation may be necessary before returning to full activity. Typically, patients return to full daily activities after three to four months. Rehabilitation and return to activity must be performed using a careful, graduated approach. Return to sport is determined by the patient's ability to perform sport-specific movements without significant pain or dysfunction, and often requires 6 to 12 months. Those with sedentary jobs can return to work shortly after injury.

Stress fractures — Among athletes involved in cutting, pivoting, and especially running sports, stress fractures of the tarsal navicular are an important cause of midfoot pain. The absence of acute trauma, relatively low level of pain, minimal swelling and inconsistent examination findings, and the difficulty identifying these fractures on routine radiographs, all combine to make stress fractures of the navicular one of the most commonly missed or delayed diagnoses in the foot. Navicular stress fractures are discussed in detail separately. (See "Stress fractures of the tarsal (foot) navicular".)

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 definitive fracture management".)

●(See "General principles of acute 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: How to use crutches (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Epidemiology and fracture types – Acute navicular fractures are uncommon and often associated with other fractures, dislocations, or soft tissue injuries within the foot. The most common types of acute navicular fractures are classified as dorsal avulsion, tuberosity, or body fractures. Navicular stress fractures are reviewed separately. (See 'Epidemiology' above and 'Clinical anatomy' above and "Stress fractures of the tarsal (foot) navicular".)

●History and examination findings – Patients with acute fractures of the navicular typically present with severe pain over the dorsal or dorsomedial foot following trauma. Localized swelling and tenderness, refusal to bear weight, and pain with eversion are common features. (See 'History and examination findings' above.)

●Diagnostic imaging – A standard series of foot radiographs (anterior-posterior, lateral, and oblique) should be obtained if there is suspicion for any midfoot fracture. Weight-bearing films are used to help assess for unstable injuries involving the midtarsal complex. Computed tomography (CT) should be performed if plain radiographs are negative but clinical suspicion persists, or if radiographs reveal a fracture. (See 'Diagnostic imaging' above.)

●Indications for surgical referral – We recommend surgical referral for most acute tarsal navicular fractures, including all fractures sustained from high-energy trauma (eg, motor vehicle collision), all tuberosity fractures, and all type II and type III body fractures. For dorsal avulsion fractures, notable indications for referral include involvement of more than 20 percent of the talonavicular articular surface and any intra-articular fragmentation. Specific indications for each fracture type are reviewed in the text. (See 'General indications for surgical referral' above and 'Presentation and management of major fracture types' above.)

●Non-operative management for appropriate fracture types – If appropriate for non-operative treatment, dorsal avulsion and tuberosity fractures can be managed with a short-leg walking cast for four to six weeks. Following a brief period of non-weight-bearing, body fractures appropriate for non-surgical management are treated with a below-the-knee walking cast for six to eight weeks. After cast immobilization, patients should receive instruction in ankle and foot range of motion exercises, and calf and peroneal muscle strengthening and stretching. The presentation and non-surgical management of each major type of tarsal navicular fracture is discussed in greater detail in the text. (See 'Dorsal avulsion fractures' above and 'Tuberosity fractures' above and 'Body fractures' above.)

●Return to activity – Return to full activity typically occurs two to three months after the initial injury for dorsal avulsion and tuberosity fractures. Return to activity may take an additional month for body fractures, treatment for which involves a lengthier immobilization.