Stress fractures of the tarsal (foot) navicular

INTRODUCTION — 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 weightbearing [1,2]. The biomechanical and vascular properties of the navicular make it susceptible to stress fracture. 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, 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. Delay in diagnosis is particularly problematic with navicular stress fractures, which at baseline are at increased risk of nonunion.

The presentation, diagnosis, and management of tarsal navicular stress fractures is reviewed here. Acute fractures to the tarsal navicular and injuries of the other tarsal bones, ankle, and leg are discussed separately. (See "Tarsometatarsal (Lisfranc) joint complex injuries" and "Metatarsal shaft fractures" and "Proximal fifth metatarsal fractures" and "Evaluation, diagnosis, and select management of common causes of midfoot pain in adults" and "Talus fractures" and "Fibula fractures" and "Ankle fractures in adults".)

EPIDEMIOLOGY AND RISK FACTORS — Stress fractures of the tarsal navicular are relatively common, comprising approximately 10 to 35 percent of all foot and ankle stress fractures [3-5]. Navicular stress fractures are seen in elite and recreational athletes, and in military personnel, with an average patient age at the time of injury of 25 to 29 years [6-9]. Overuse or excessive mechanical stress due to improper training programs, poor equipment (eg, worn running shoes, hard surfaces), improper running technique, and anatomic variants may all increase the risk for navicular stress fracture [10]. Female athletes appear to be at greater risk [11]. Of note, up to 30 percent of tarsal navicular stress fractures are missed primarily or are treated in a delayed manner. Delays in treatment result in poorer outcomes compared with injuries diagnosed and treated promptly [12]. The general risk factors for stress fractures are reviewed in detail separately. (See "Overview of stress fractures", section on 'Risk factors'.)

Athletes who participate in track and running sports, including sprinters and hurdlers, are especially prone to navicular stress fracture [7,9,11,13-15]. In one retrospective study of 180 high-level athletes with stress fractures, 59 percent of all tarsal navicular stress fractures occurred in track athletes and the majority of these were found among distance runners [3]. However, these fractures have been reported in military recruits and participants in soccer (football), Australian rules football, jumping sports (eg, basketball), gymnastics, and dance.

Small observational and laboratory studies suggest that certain anatomic variants may place greater stress on the tarsal navicular during running, thereby increasing the risk for stress fracture. Metatarsus adductus (forefoot varus) and the combination of a short first metatarsal and a relatively long second metatarsal may increase biomechanical stress and have been noted in a number of case reports [16]. Other such variants may include cavus foot (high arch) [17].

While most midfoot injuries involve both ligament and bone, stress fractures of the tarsal navicular are less likely to be associated with ligament injury. However, concomitant injury to the articular cartilage of the surrounding navicular joints may be seen.

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

The tarsal navicular acts as a keystone for the medial column and longitudinal arch of the foot (figure 1). It articulates with the talus proximally, the cuboid medially, and the medial, intermediate, and lateral cuneiforms distally. Strong ligamentous connections unite the five bones that form the mid-tarsal complex (navicular, cuboid, and cuneiforms) (figure 2 and figure 3 and figure 4). Several clinically important ligaments attach to the navicular, including: the posterior tibialis tendon, which inserts on the navicular tuberosity; a portion of the deltoid ligament, which inserts on the anterior body; and the plantar calcaneonavicular (or, "spring") ligament, which originates at the sustentaculum tali of the calcaneus and inserts along the medial and plantar aspects of the navicular. Dorsal and plantar cuneonavicular and cuboideonavicular ligaments provide further support.

The biomechanical role and vascular anatomy of the tarsal navicular combine to make it highly susceptible to stress fracture [18]. During running, compressive forces on the navicular create a zone of maximum shear stress in the central third of the navicular body, particularly during the foot-strike phase of gait [2]. The navicular receives its blood supply from branches of the dorsalis pedis artery dorsi-laterally and branches of the tibialis posterior artery along its plantar and medial aspects. This perfusion network is robust along the periphery of the navicular but creates a relatively avascular "watershed" region in the central third of the bone in some patients, increasing the risk for stress-related injury and delayed healing. However, the frequency and role of relative avascularity in the development of navicular stress injury is debated [19]. The combination of high biomechanical stress and vascular watershed creates a region in the central navicular that is susceptible to injury, and this is in fact where the majority of stress fractures develop.

Running gait can be altered by limitations in joint mobility, which can in turn increase the stress placed on particular structures. While evidence is limited, some researchers think that reduced mobility at the ankle (eg, limited dorsiflexion) and subtalar joints may increase the stresses placed upon the navicular during running [17,20].

MECHANISM OF INJURY — Overuse stress fractures, regardless of location, share a common underlying mechanism of injury. Local bone metabolism becomes imbalanced due to the stress of repeated workloads, and bone formation cannot compensate adequately for increased bone resorption. In the case of tarsal navicular stress fractures, cumulative biomechanical stress, typically from running, outstrips the navicular's capacity to compensate. The pathophysiology of stress fractures is reviewed separately. (See "Overview of stress fractures", section on 'Pathophysiology'.)

HISTORY AND EXAMINATION FINDINGS — Patients with a tarsal navicular stress fracture typically present anywhere from a few weeks to many months following the onset of pain, often after conservative measures and activity modification have failed to alleviate symptoms. A review of 315 navicular stress fractures, primarily in athletes, reported the average duration of symptoms before diagnosis to be nearly 10 months [21].

Pain typically begins insidiously and gradually develops into a nagging, deep, dull ache that may occur with simple ambulation in some but only with high impact activities (eg, running) in others. Rest typically relieves the pain. While some patients localize the pain to a focal point over the dorsomedial midfoot, others may struggle to localize their symptoms and may indicate maximal pain anywhere between the metatarsals and the tibial (medial) malleolus. However, pain is typically present in the general region of the navicular along its dorsal or medial aspect. Persistent medial arch pain, particularly pain that occurs during sleep, is highly suggestive and warrants a careful diagnostic workup.

Rarely, an athlete recalls feeling a "pop" or "snap" during a sharp cut or stop or landing that heralded the onset of pain. Some athletes may remember their symptoms beginning after a particularly long or intense training session. But most affected athletes cannot recall a specific mechanism or time of onset, reporting instead a dull, deep midfoot ache that developed gradually and has persisted. White female distance runners with low BMI, thinner bone structure, and a history of oligo- or amenorrhea are at particularly high risk.

Physical examination findings in patients with a navicular stress fracture are notoriously benign. Inspection is usually normal, with no swelling or deformity noted; range of motion, strength, and neurovascular assessments are also typically normal. Tenderness of the navicular is the most commonly reported positive finding. In one retrospective study, 17 of 21 patients (81 percent) experienced tenderness at the high point of the dorsal navicular, between the tibialis anterior and extensor hallucis longus tendons, sometimes referred to as the "N spot" (picture 1) [22]. Hopping or standing on the tiptoes of the affected foot may elicit pain. (See 'Management' below.)

During examination, the clinician should observe the foot closely and note the presence of any anatomic features associated with stress fracture. These include pes cavus (high arch) (picture 2), excess supination, forefoot varus, the combination of a short first metatarsal with a relatively longer second metatarsal (picture 3), and a high arch combined with metatarsus adductus. Such findings raise suspicion for a navicular stress fracture.

DIAGNOSTIC IMAGING — In the patient with a suspected tarsal navicular stress fracture, weightbearing three-view plain radiographs (anterior-posterior [AP], lateral, and oblique) of the foot are the initial studies obtained (image 1) [23]. While bilateral films of the affected and unaffected feet can provide useful comparisons and help to identify subtle changes associated with a bone stress reaction, these are rarely obtained as advanced imaging is typically ordered when plain films are indeterminate. If plain radiographs reveal signs of a stress fracture, further imaging is often unnecessary. Nevertheless, the sensitivity of plain radiographs for identifying navicular stress fractures is poor [18,24]. As an example, one review of 77 computed tomography (CT)-confirmed navicular stress fractures found positive plain radiographs in only 18 percent of cases [25].

When plain films are negative but clinical suspicion for a stress fracture remains high, magnetic resonance imaging (MRI) or CT can be used to diagnose and classify these injuries (image 2) [26]. MRI offers better soft tissue resolution than CT or bone scan. This is important as ligamentous injury and posterior tibial tendon enthesopathy are important considerations in the differential diagnosis for navicular stress fracture. In addition, improved MRI technology may allow for diagnosis of stress reactions early in the course of injury (as may bone scan), enabling clinicians to initiate definitive treatment before an actual fracture has developed.

In some cases, computed tomography may be preferred to MRI when advanced imaging is needed. CT provides high resolution of bone and allows for more precise differentiation among fracture types. In a review of 62 navicular stress fractures, CT was performed initially in 38 patients and was 100 percent sensitive, while MRI was performed initially in 49 patients and demonstrated 71 percent sensitivity [27]. These results are consistent with those of a similar observational study in which CT identified six additional navicular stress fractures compared to MRI among the 19 patients evaluated [28]. In addition, CT allows for accurate classification and serial scans to assess healing [27].

In the authors’ practice, either CT or MRI is an acceptable initial choice for advanced imaging. Local practice will likely vary based on available resources and expertise. Both MRI and CT scan are used with some frequency in the diagnosis of navicular stress fractures. MRI has decreased sensitivity compared with CT scan. The absence of a fracture line on MRI does not rule out the presence of a stress fracture, and a CT scan may be needed if only a stress reaction is noted initially.

Given the superficial location of the navicular, clinicians skilled in the use of musculoskeletal ultrasound may use this technique as an initial screen for navicular injury. However, the test characteristics of ultrasound for identifying a navicular stress fracture are not well studied and the technique is highly operator-dependent. Hence, ultrasound should be viewed as a preliminary and limited screening tool that is helpful only if it reveals positive findings. It cannot be used to rule out a stress fracture.

While triple-phase bone scan is positive in the very early stages of injury (eg, stress reaction prior to fracture) in nearly all cases and is useful as an initial study when injury is suspected, clinical use of bone scan has declined dramatically in hospitals where MRI is available [28,29]. This is primarily because bone scan lacks specificity and may be positive in the setting of tumor or infection. If a bone scan is negative, additional imaging is generally unnecessary unless clinical suspicion remains high. However, if a bone scan is positive, CT or MRI may still be needed to further characterize the abnormality.

INDICATIONS FOR SURGICAL REFERRAL — The four general indications for surgical referral in patients with a navicular stress fracture are described below:

●Complicated fractures (type 2 or type 3 fractures) ‒ Tarsal navicular stress fractures begin at the dorsal cortex and may then extend further into the bone. Stress fractures that extend through the dorsal cortex into the body of the navicular (type 2 fracture) or propagate across the bone into the far cortex (complete or type 3 fracture) warrant referral to a surgeon with experience managing tarsal navicular injuries. Fractures that extend into the relatively avascular body of the navicular or that involve two cortical surfaces are at higher risk for nonunion and delayed healing. Small studies report that surgical fixation allowed elite athletes with complex fractures to return to play two months earlier than those managed nonoperatively [7].

●Concomitant injury ‒ Although concomitant injury is uncommon with navicular stress fractures, such injuries may occur and clinicians must be reasonably certain that no such injury is present before beginning nonoperative management. Patients with concomitant injuries (eg, ligament tear, additional fracture) should be referred to a surgeon with experience in the management of navicular injury, as they are more likely to require surgical intervention.

●Delayed presentation – Classic teaching is that stress fractures diagnosed more than three months after symptom onset are at higher risk for nonunion and long-term complications, and should be managed surgically. However, several observational studies report that even long-standing navicular stress fractures can heal completely if treated with eight weeks of cast immobilization and strict non-weightbearing. Nevertheless, following delayed presentation of a navicular stress fracture, we believe the most prudent course is to refer the patient to a surgeon experienced in the management of these injuries.

●Athlete or patient preference – Some observational studies report that surgical fixation of navicular stress fractures provides athletes with a more certain and shorter time frame for returning to play than nonoperative management [21]. Even with injuries amenable to conservative care, some athletes, particularly elite adult athletes, may prefer surgical treatment in order to speed their return to play. Such patients should be referred. (See 'Selecting surgical or nonsurgical management' below.)

DIAGNOSIS — The diagnosis of tarsal navicular stress fracture can be difficult to establish, but given the relatively high risk of nonunion, an aggressive workup is justified in patients who are at risk. Definitive diagnosis is made by an imaging study, most often magnetic resonance imaging (MRI) or computed tomography (CT). The history and examination findings are often nonspecific, but the injury is most common in runners, who typically complain of pain along the dorsal or medial aspects of the midfoot in the vicinity of the navicular that increases with weightbearing activity and decreases with rest. (See 'Diagnostic imaging' above and 'History and examination findings' above.)

DIFFERENTIAL DIAGNOSIS — Navicular stress fractures occur from cumulative overuse, often due to running. Myriad other conditions of the foot can develop from this same mechanism and present with vague medial midfoot pain without a clear precipitating event. Thus, the differential diagnosis is broad and includes stress injury to other bones (eg, cuboid, metatarsals, talus, calcaneus), ligament injury (eg, plantar calcaneonavicular [or, "spring"] ligament strain), articular cartilage injury of the midfoot joints, avascular necrosis, and bony neoplasm. Given the nonspecific presentation of many of these conditions, advanced diagnostic imaging, typically magnetic resonance imaging (MRI) or computed tomography (CT), is required to establish a definitive diagnosis.

Three important conditions that more commonly mimic navicular stress fracture are the following:

●Posterior tibialis tendinopathy near its insertion on the navicular. Posterior tibialis tendinopathy or enthesopathy is often associated with redness and swelling at the medial ankle or midfoot, accompanied by focal tenderness at the tendon insertion, and is made worse by passive stretching of the tendon. Ultrasound may reveal signs of tendinopathy, while MRI is usually diagnostic and shows the full extent of injury.

●Traumatic separation of an accessory navicular bone. The accessory navicular stems from a distinct ossification center of the navicular tuberosity that exists in about 10 percent of people and is generally asymptomatic. The accessory bone may cause medial foot pain with activity, but in adults, this occurs more often following acute foot trauma. Plain radiographs reveal the accessory bone in most cases. MRI is necessary if concern remains that a navicular stress fracture may account for the patient's symptoms.

●Tear (partial or complete) of the plantar calcaneonavicular (or, "spring") ligament. Spring ligament tears cause medial arch pain, and complete tears can cause collapse of the longitudinal foot arch, which must be assessed with the patient bearing their full weight. MRI is the best tool for diagnosis and distinguishes ligament tear from stress fracture.

A general differential diagnosis for patients presenting with midfoot pain in the region of the navicular without major acute trauma is reviewed separately. (See "Evaluation, diagnosis, and select management of common causes of midfoot pain in adults", section on 'Medial arch (navicular) injury'.)

MANAGEMENT

Selecting surgical or nonsurgical management — Tarsal navicular stress fractures begin at the dorsal cortex and may then extend further into the bone. Fracture type helps to determine management. A classification scheme for tarsal navicular stress fractures (originally based on computed tomographic [CT] appearance) is as follows [7,27]:

●Type 0.5 – Stress reaction on MRI; CT normal

●Type 1 – Fracture limited to dorsal cortex

●Type 2 – Fracture line extends into navicular body

●Type 3 – Fracture line extends from dorsal into plantar cortex

Evidence to inform decisions about the management of more severe navicular stress fractures is limited. We believe that type 1 tarsal navicular stress fractures without other complicating factors should be treated with immobilization and non-weightbearing, and may be managed by primary care clinicians comfortable with fracture management [30,31]. Type 2 and type 3 navicular stress fractures should be referred to a surgeon with experience managing these injuries. Other potential indications for surgical referral are described above. (See 'Indications for surgical referral' above.)

Particularly when sclerosis is apparent at the fracture line, type 3 and type 2 navicular stress fractures are at higher risk of nonunion and poor outcome when managed conservatively [6,7]. We treat patients with a suggestive history, evidence of a stress reaction at the navicular on diagnostic imaging, and no other complicating factors as if they have a type 1 stress fracture, although the period of non-weightbearing may be slightly shorter. Patients awaiting surgical referral are placed in a supportive boot or cast and should be non-weightbearing. Observational evidence suggests that conservative care of navicular stress fractures that permits weightbearing in a manner similar to the approach used for other lower extremity stress fractures leads to poor outcomes, even with relatively minor injuries [25,32].

Preferences among some clinicians for operative repair of navicular stress fractures are based largely on observational studies that report improved clinical outcomes and a shorter time for returning to play with surgical management [7,21,33]. A systematic review of observational studies of management of navicular stress fracture (n = 315) reported successful outcomes in 104 of 108 cases treated surgically (96 percent) and an average return to play of just over four months [21]. Of these cases, long-term follow-up data were available for 78, and there was one report of refracture. In contrast, of the 207 fractures managed nonoperatively, 149 reported successful outcomes (72 percent), and the average return to play was closer to five months. Of these non-surgical cases, long-term follow-up data were available for 85, and there were 20 refractures. While this review has prompted some to recommend surgical treatment for all navicular stress fractures (types 1, 2, and 3) [34], it should be noted that the included studies were all uncontrolled and observational. Thus, it is premature to draw definitive conclusions about the best management for all navicular stress fractures.

For fractures amenable to either surgical or conservative management, patients can select the approach best suited to their priorities and their willingness to accept the small risk of surgical complications. In clinical practice, it is most important that the patient be thoroughly evaluated and counseled by a clinician with experience in the management of these injuries, be that a surgeon, sports medicine physician, or primary-care clinician. The patient can then weigh the relative risks and benefits of available treatments.

Nonsurgical management

Stress reaction — The patient with a navicular stress reaction (ie, injury type 0.5) should be placed in a well-molded, short-leg cast. Strict non-weight bearing is required for at least three weeks; six weeks may be preferred by some clinicians. After the initial period of immobilization, the patient can be transitioned to partial weightbearing and then full weight bearing in a cast boot (picture 4) over the following two weeks. During the progression from non-weightbearing to full weightbearing, and in subsequent phases of rehabilitation, the patient should report any recurrence of midfoot pain immediately. Recurrent pain should prompt re-evaluation and likely re-imaging with CT to evaluate healing.

Stress fracture without extension into plantar cortex — The patient with a navicular stress fracture that does not extend into the plantar cortex (ie, injury types 1 and 2) who elects nonsurgical management should be placed in a well molded, short-leg cast (extends from just below the knee to the forefoot – ankle and midfoot are immobilized). Strict non-weightbearing is required for a minimum of six weeks. Activity limitation without immobilization and partial non-weightbearing (the approach used to treat many other stress fractures) has proven to be inadequate for navicular stress fractures [22,25,28,29]. The classic study of navicular stress fracture management reported that treatment with a non-weightbearing cast for six weeks produced substantially higher cure rates (19 of 22 patients, or 86 percent, returned to full sport) than the traditional approach emphasizing activity limitation (9 of 34 patients, or 26 percent, returned to full sport) [25].

Stress fracture extending into plantar cortex — Any patient with a navicular stress fracture that extends into the plantar cortex (ie, type 3 fracture) should be referred to a surgeon with experience managing such injuries. (See 'Indications for surgical referral' above and 'Selecting surgical or nonsurgical management' above.)

After six weeks of non-weightbearing immobilization, the patient is re-examined with the cast removed. If the navicular is non-tender and the patient has no pain with passive and active range of motion testing of the midfoot, then rehabilitation may begin. The initial phase of rehabilitation is performed in a weightbearing cast-boot. If tenderness persists, immobilization using a cast or cast-boot and non-weightbearing are continued, and the patient is re-assessed at two week intervals until all tenderness has resolved and there is no pain with passive and active midfoot motion. If after 10 to 12 weeks, symptoms are not resolved, CT imaging should be used to evaluate fracture healing. If insufficient healing is noted on CT, the patient should be referred to a surgeon for possible open bone grafting and surgical fixation.

In patients who become clinically asymptomatic and progress normally through rehabilitation, repeat radiographic evaluation to document healing is not necessary. Radiographic healing lags behind clinical healing and abnormalities may persist on plain radiographs for years [10]. For patients with a history of multiple stress fractures or features of the female athlete triad (menstrual dysfunction, low bone mineral density, insufficient caloric intake), a more comprehensive assessment may be required, including laboratory studies and nutritional and psychiatric evaluation. (See "Overview of stress fractures" and "Functional hypothalamic amenorrhea: Pathophysiology and clinical manifestations".)

FOLLOW-UP CARE AND PREVENTION — Once the patient is able to tolerate full weightbearing in a cast or walking boot, the patient can begin a rehabilitation program similar to those used for other lower extremity stress fractures. These programs progress from minimal impact activities (eg, aquatics, stationary cycling) to maximal impact activities (eg, running) over a period of four to eight weeks. The rehabilitation program must progress gradually and be closely supervised. Potential underlying risk factors should be assessed and modified as needed before the patient resumes maximal impact activities. Stiffness and mild discomfort is common during the early stages of rehabilitation and should improve over time. However, if pain localizes to the navicular, careful re-assessment is necessary, possibly including re-immobilization, advanced diagnostic imaging, and surgical referral. A sample rehabilitation program used by one of our contributors to assist runners recovering from an uncomplicated navicular stress fracture managed nonsurgically is provided in the following table (table 1).

A history of stress fracture is an important risk factor for reinjury [35]. Therefore, it is important to address any correctable intrinsic or extrinsic risk factors. Interventions may include the following [36,37]:

●Vitamin D and calcium supplementation for patients with vitamin D insufficiency or low bone density. (See "Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment".)

●Nutrition assessment for patients with low body mass index or possible inadequate caloric intake.

●Mobility training program for patients with motion restrictions that increase the stress placed on the navicular. These may include limited ankle dorsiflexion and excessive foot pronation [14,20].

●Biomechanics assessment and instruction for runners and others with high-risk running gait or movement patterns. Such assessment may identify the need for specific rehabilitation of muscles higher in the kinetic chain (eg, weak hip external rotators or quadriceps) or a shoe insert (orthotic) to ensure proper mechanics during sport.

●Orthotic use. As many navicular stress fractures are thought to be associated with abnormal biomechanical stress at the medial midfoot, most clinicians place athletes recovering from such injuries in a custom orthotic that supports the entire longitudinal arch and corrects excessive pronation or supination. In addition, the orthotic should correct other anatomic issues such as leg length inequality.

●Change in running surface and/or running shoes, if these may be contributing to injury risk. (See "Running injuries of the lower extremities: Risk factors and prevention", section on 'Running shoe design'.)

●Reductions or other modifications in training volume, particularly for those who have sustained prior stress fractures.

General recommendations and further discussion of the prevention of stress fractures are provided separately. (See "Overview of stress fractures", section on 'Prevention'.)

COMPLICATIONS — Overall, stress fractures of the navicular are among the most complex bone stress injuries with nearly 25 percent of patients experiencing some complication during healing [38]. Delayed union and nonunion are the most common complications. Data is limited, but even with early diagnosis and proper treatment, the rates of delayed and nonunion may be as high as 10 to 20 percent [8,30].

Complications of tarsal navicular stress fractures treated surgically include infection, delayed wound closure, hardware failure, and persistent pain from hardware, as well as other known risks of surgery. Other potential complications are less common and are those associated with any fracture. (See "General principles of fracture management: Early and late complications".)

RETURN TO WORK AND SPORT — The average time required for a patient with a tarsal navicular stress fracture to return to full activity varies depending upon the extent of the fracture and the mode of treatment. According to a systematic review that included 343 cases of navicular stress fracture, the overall rate of return to sport was 83 percent (95% CI 70.7-90.9) and the mean time required was 127 days (95% CI 103-151) [38].

For stress fractures involving only the dorsal cortex that are managed nonoperatively with six weeks of casting and non-weightbearing, patients typically return to full sports participation between three to six months from the time treatment is initiated [6,7,10]. Once clinical healing is evident (no tenderness over the navicular and no pain with active and passive midfoot motion), our preference is to maintain the patient in a well-molded walking cast or a prefabricated cast-boot for two weeks of partial weightbearing, and then an additional two weeks of full weightbearing (four weeks total). Braces and walking boots may be used during this stage, but care must be taken to ensure that these braces and boots provide support to the midfoot during weightbearing activities.

Return to sport is determined by the patient's ability to perform sport-specific activities without significant pain or dysfunction. Those with sedentary jobs can return to work shortly after injury as long as they are able to maintain non-weightbearing status.

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: General fracture and stress fracture management in adults" and "Society guideline links: Lower extremity (excluding hip) fractures in adults" and "Society guideline links: Acute pain management".)

SUMMARY AND RECOMMENDATIONS

●Clinical anatomy and mechanics – The tarsal navicular bone is the keystone of the medial column of the foot (figure 1), bearing the majority of the load applied to the tarsal complex during weightbearing. Due to these biomechanical loads and its vascular properties, the bone is susceptible to stress fractures and healing disturbances. (See 'Clinical anatomy and biomechanics' above.)

●Epidemiology, risk factors, and complications – Stress fractures of the navicular are relatively common, particularly among runners. Female athletes appear to be at greater risk. Up to 30 percent of navicular stress fractures are missed primarily or are treated in a delayed manner, which increases the risk for nonunion and other complications. (See 'Epidemiology and risk factors' above.)

●History and physical examination – Diagnosis of navicular stress fracture can be difficult. Patients can present anywhere from a few weeks to several months after the onset of pain and typically complain of vague midfoot pain exacerbated by impact activities (running) and alleviated by rest. Examination may reveal tenderness directly over the dorsal aspect of the navicular (picture 1) but may be normal. Hopping or standing on the tiptoes of the affected foot may elicit pain. (See 'History and examination findings' above.)

●Diagnostic imaging – Plain radiographs are the first studies to obtain when navicular stress fracture is suspected, and are useful when positive, but have limited sensitivity. Advanced imaging is often necessary for diagnosis. Both MRI and CT are reasonable options for evaluation of a potential navicular stress fracture. Each has advantages and limitations; selection may be based on available resources and physician experience. (See 'Diagnostic imaging' above and 'Diagnosis' above.)

●Indications for surgical referral – The four general indications for surgical referral are the following:

•Complicated fracture: Fracture extends through the dorsal cortex into the body of the navicular (type 2 fracture) or propagates across the bone into the far cortex (complete or type 3 fracture).

•Concomitant injury, such as ligament tear or second fracture.

•Delayed presentation, generally defined as fracture diagnosed more than three months after symptom onset.

•Athlete or patient preference. (See 'Indications for surgical referral' above.)

●Differential diagnosis – Navicular stress fractures occur from cumulative overuse, often due to running. Myriad other conditions of the foot can develop from this same mechanism and present with vague medial midfoot pain without a clear precipitating event. Diagnostic imaging is generally needed to distinguish among alternative diagnoses. Important conditions that commonly mimic navicular stress fracture include: posterior tibialis enthesopathy; accessory navicular injury; and, plantar calcaneonavicular (or, "spring") ligament tear. (See 'Differential diagnosis' above and "Evaluation, diagnosis, and select management of common causes of midfoot pain in adults".)

●Management – Uncomplicated navicular stress fractures that do not extend beyond the dorsal cortex and are not associated with concomitant injury are managed with a short-leg, non-weightbearing cast for six to eight weeks. Return to full sports participation typically requires four to six months with nonsurgical management. More complex injuries are referred to a surgeon. (See 'Management' above and 'Follow-up care and prevention' above and 'Return to work and sport' above.)