Stress fractures of the metatarsal shaft

INTRODUCTION — Metatarsal stress fractures were first described by Briethaupt in 1855 and termed "march fractures," as they commonly occurred in military recruits. Stress fractures of the metatarsal shaft, not including the fifth metatarsal, are reviewed here. An overview of stress fractures, a detailed discussion of fifth metatarsal fractures, and non-stress fractures of the metatarsals are all discussed separately. (See "Overview of stress fractures" and "Proximal fifth metatarsal fractures" and "Metatarsal shaft fractures" and "Metatarsal and toe fractures in children".)

CLINICAL ANATOMY AND BIOMECHANICS — For reference purposes, the metatarsals are numbered from first (largest) to fifth (smallest) (figure 1 and figure 2A and figure 2B and figure 2C and figure 3 and figure 4). The first metatarsal is larger than the others and less likely to develop a stress fracture. A disproportionate number of stress fractures occur in the second metatarsal shaft, especially at the neck. Several anatomic mechanisms are proposed to explain this phenomenon. The base of the second metatarsal is recessed and more firmly fixed at the tarsal-metatarsal joint, via ligamentous attachment to the first and second cuneiforms, than the other metatarsals [1,2]. The resulting increased rigidity probably allows less motion in the sagittal plane at the metatarsal base and increases bending forces in the second metatarsal diaphysis [3].

According to an alternative mechanism, if the second metatarsal is longer than the first (ie, Morton foot), the second metatarsal is subjected to greater amounts of stress [2,4,5]. It is debated whether this increased stress is due to the increased length of the second metatarsal or to the decreased mobility of the first metatarsal [3]. As the forefoot pronates during normal gait, the first metatarsal dorsiflexes and transfers load to the lesser metatarsals. The second metatarsal receives a greater share of this load than the other metatarsals.

Dorsal and plantar metatarsal arteries run adjacent to the metatarsals, while branches of the lateral and medial plantar nerves run in the vicinity of the metatarsals (figure 5 and figure 6 and figure 7).

EPIDEMIOLOGY AND RISK FACTORS — A range of factors that increase weight-bearing loads on particular metatarsals or decrease the ability of metatarsals to handle such loads predispose individuals to stress fractures [4-9]. These factors include the following:

●Anatomic abnormalities:

•Dorsal or plantar-flexed metatarsals

•Relatively long second metatarsal (see 'Clinical anatomy and biomechanics' above)

•Excessively tight gastrocnemius and soleus muscles

•Pes planus ("flat") foot structure

●Physiologic abnormalities:

•Obesity

•Osteopenia (ie, low bone mineral density) – Osteopenia may be due to any of several causes, including relative energy deficiency in sport (sometimes referred to as the female athlete triad), malabsorption syndromes, bariatric surgery, poor nutrition, medication (eg, glucocorticoid), or excessive alcohol use [10]

•Poor aerobic fitness

•Poor muscle strength/endurance

●External factors:

•Poorly fitting shoes

•Abrupt increases in training volume or intensity

•Change in training surface

Any preexisting causative factor must be effectively addressed or injury will recur. The risk factors generally associated with stress fractures are reviewed in detail separately. (See "Overview of stress fractures", section on 'Epidemiology' and "Functional hypothalamic amenorrhea: Pathophysiology and clinical manifestations", section on 'Clinical manifestations'.)

In athletes, the incidence of metatarsal stress fractures is second only to that of tibial stress fractures [3]. Stress fractures of the second, third, and fourth metatarsals account for 90 percent of all metatarsal stress fractures [3]. They are seen more often in the pes planus (flat) foot, compared with tibial stress fractures, which occur more frequently in a pes cavus (high arched) foot. Metatarsal stress fractures may occur several weeks after an abrupt increase in activity or with chronic overload. First metatarsal stress fractures are rare and usually occur around the metaphyseal-diaphyseal junction [3]. Proximal metatarsal stress fractures, particularly of the fifth metatarsal, have a worse prognosis and generally require more aggressive treatment [4,5,11]. (See "Proximal fifth metatarsal fractures", section on 'Stress fractures of proximal diaphysis: Zone 2 injury'.)

Data concerning the relative rates of metatarsal stress fractures associated with particular activities is limited. However, stress fractures are commonly reported with certain activities. These include military basic training, dance (especially proximal second metatarsal fractures), and running. Runners who switch from standard running shoes to minimalist shoes may be at increased risk. (See "Running injuries of the lower extremities: Risk factors and prevention", section on 'Running barefoot or with minimalist shoes'.)

MECHANISM OF INJURY — Metatarsal stress fractures result from repetitive stress to the forefoot, usually from running, jumping, dancing, and other repetitive weight-bearing activities [1-5,8,10]. (See 'Epidemiology and risk factors' above.)

CLINICAL PRESENTATION AND EXAMINATION — Patients with stress fractures of the metatarsal shaft typically complain of gradually worsening pain in their forefoot. The pain may be poorly localized in the forefoot or focal over a particular metatarsal. When asked, patients may describe starting a new activity or athletes may describe increasing their training volume or intensity a few weeks before the pain began. Initially the pain is intermittent and occurs only with use. If the patient continues to perform the activity that caused the stress fracture, the injury can progress, leading to more extensive swelling, severe pain even with normal activities, and frank fracture.

On examination, the clinician may find point tenderness over a particular metatarsal shaft (figure 2A-C). Gentle axial loading of the metatarsal head may produce pain at the fracture site [3]. This is done by holding the toe in line with its corresponding metatarsal (ie, without angulation) and pushing the toe in toward the metatarsal (ie, in line with the long axis of the metatarsal). This maneuver produces pain if the metatarsal is fractured, but generally does not produce pain in patients with an isolated soft tissue injury [12]. Most patients are able to bear weight, but this usually causes pain.

DIAGNOSTIC IMAGING — Early stress fractures are often not apparent on plain radiographs. The first radiographic evidence of a stress fracture usually occurs no earlier than two to six weeks after the onset of symptoms [3,12]. Narrowing of the medullary canal, cortical hypertrophy, faint lucency, and periosteal thickening develop first, followed by callus formation, sometimes as early as four to five weeks after symptom onset. Distinct, well-organized callus is usually seen after several months (image 1).

As the outer surface of the cortex of metatarsal bones is relatively superficial, at least dorsally, ultrasonography has a role in the diagnosis of metatarsal stress fractures in cases where initial radiographs are normal, but clinical suspicion for fracture is high. Periosteal edema may be seen with ultrasound prior to the appearance of abnormalities on plain radiograph. In a pilot study of 37 patients with pain and swelling for an average of six weeks, the sensitivity of ultrasound for diagnosing metatarsal stress fractures in patients with negative radiographs was 83 percent and specificity 76 percent compared to MRI (image 2) [13].

Magnetic resonance imaging (MRI) and technetium bone scanning are the most sensitive methods for confirming the diagnosis of stress fracture in their early stages, having been found to be accurate as early as 48 to 72 hours after symptom onset in some studies (image 3). Computed tomography (CT) studies may be performed if more detail about the precise nature and location of the fracture, or how much healing has occurred, is needed. However, advanced imaging studies may be unnecessary, as a presumptive clinical diagnosis can often be made in patients with a suggestive history and examination findings [3]. A more detailed discussion of imaging techniques for stress fractures is found separately. (See "Overview of stress fractures", section on 'Imaging studies'.)

DIAGNOSIS — In most instances, a clinical diagnosis of a stress fracture of the metatarsal shaft is sufficient. This diagnosis is based upon a suggestive history of a recent increase in weight-bearing activity, a complaint of diffuse or focal forefoot pain, and focal tenderness or pain at a particular metatarsal shaft.

When a definitive diagnosis is required, the suggested order of testing is plain radiographs, followed by ultrasound, magnetic resonance imaging, and finally technetium bone scanning if all prior testing is negative [13], or computed tomography if more detailed information about fracture location is needed [10].

DIFFERENTIAL DIAGNOSIS — Metatarsal stress fractures are often diagnosed clinically, and imaging studies obtained early after the onset of symptoms may be unrevealing. Therefore, a number of alternative diagnoses are possible. The most important and common of these are listed below, along with important clinical means for distinguishing them, and links to topics with additional detail.

●Muscle/tendon strain – Pain in the forefoot may be caused by a muscle or tendon strain. In such cases, pain increases with resisted flexion or extension of the involved joint (eg, second toe extension), while pain from a metatarsal fracture increases with direct palpation or axial loading of the metatarsal. (See "Evaluation, diagnosis, and select management of common causes of forefoot pain in adults".)

●Toe or metatarsal shaft fracture ‒ Non-stress fractures of a toe or metatarsal shaft are typically associated with a history of trauma and are apparent on plain radiographs (image 4), while the symptoms associated with stress fractures are insidious in onset and there is no history of direct trauma. (See "Metatarsal shaft fractures" and "Toe fractures in adults" and "Metatarsal and toe fractures in children".)

●Turf toe – “Turf toe” is a strain of the metatarsophalangeal joint resulting from forceful hyperextension of the great toe. Pain increases with resisted flexion of great toe. Stress fractures of the first metatarsal are uncommon, and pain is exacerbated by direct palpation or axial loading of the involved metatarsal. (See "Evaluation, diagnosis, and select management of common causes of forefoot pain in adults", section on 'First metatarsophalangeal joint sprain ("turf toe")'.)

●Metatarsalgia – Metatarsalgia is a general term for pain at the ball of the foot. Pain is often localized around the metatarsal heads on plantar surface, distal to the metatarsal shafts. Direct palpation of the metatarsal shaft typically does not exacerbate metatarsalgia. (See "Evaluation, diagnosis, and select management of common causes of forefoot pain in adults", section on 'Metatarsalgia'.)

●Sesamoiditis/sesamoid stress fracture – Pain from sesamoid pathology increases with direct palpation of either the medial or lateral sesamoid at the plantar surface, both of which lie superficial and distal to the first metatarsal (figure 2C and figure 2B and image 5). (See "Sesamoid fractures of the foot".)

●Morton neuroma – A neuroma can develop in the interdigital nerves. Pain from a neuroma is exacerbated by simultaneous medial and lateral compression of the distal metatarsals (ie, squeezing them together), as opposed to direct palpation of the bone, which increases the pain from a metatarsal stress fracture. (See "Running injuries of the lower extremities: Patient evaluation and common conditions", section on 'Morton neuroma'.)

●Plantar fasciitis – Plantar fasciitis causes pain along the plantar fascia that is usually most prominent close to the heel near the fascial origin at the calcaneus (picture 1). (See "Plantar fasciitis".)

●Ligament sprain – A ligament sprain usually presents with a history of acute trauma whereas stress fracture presentations are typically more insidious. Patients with a ligament sprain often complain of pain at the midfoot and have difficulty performing a single limb heel raise. Pain may be elicited by moving one metatarsal head in the sagittal plane (ie, dorsal-plantar motion) relative to an adjacent metatarsal head. If a definitive diagnosis is needed, imaging studies (eg, MRI) may be necessary. Sprains of midfoot ligaments are challenging to diagnose and treat, and referral to a specialist may be needed.

●Osteomyelitis – Osteomyelitis most often occurs from the spread of a contiguous soft tissue infection or following trauma or surgery. Such a history is not consistent with a stress fracture. Constitutional and local signs of infection may be present with osteomyelitis but typically do not occur with a stress fracture. (See "Nonvertebral osteomyelitis in adults: Clinical manifestations and diagnosis".)

●Bone cyst or tumor – A bone cyst or tumor typically presents with pain when bearing weight, and changes in the bony architecture are apparent on plain radiographs, possibly including a pathologic fracture.

Imaging with plain radiographs is often most useful for helping to exclude alternative diagnoses, such as a late-stage sesamoid stress fracture, osteomyelitis, and bone cysts or tumors. A radiograph demonstrating a metatarsal shaft stress fracture at the site of pain would help to rule out other conditions.

TREATMENT — In most cases, the treatment of a metatarsal stress fracture consists of basic analgesia and rest, which allows the fracture to heal. Immobilization and making the patient non-weight-bearing are often unnecessary.

Initial treatment — The pain associated with most metatarsal stress fractures is adequately treated with ice, acetaminophen, and activity modification. The effect of nonsteroidal antiinflammatory drugs (NSAIDs) on fracture healing remains a source of debate, which is discussed separately. (See "Overview of COX-2 selective NSAIDs", section on 'Possible effect on fracture healing'.)  

Metatarsal stress fractures usually respond well to cessation of the inciting activity (eg, marching, dancing, running) for four to eight weeks [2]. In some instances the use of a stiff soled orthopedic shoe or a walking boot may be helpful for patients who continue to have pain despite cessation of the inciting activity. If pain persists with simple walking, a period of unloading (usually a week or two) may be helpful until walking is no longer painful. Unloading can be accomplished by making the patient partial or non-weight-bearing with crutches or other means. For partial weight-bearing, the patient can use the heel of the affected foot. In patients with severe pain, a short-leg cast and non-weight-bearing can be used for a short period (eg, one to two weeks).

Most metatarsal stress fractures do not require casting or immobilization, fractures of the fifth metatarsal being a notable exception. Fifth metatarsal stress fractures are discussed separately. (See "Proximal fifth metatarsal fractures", section on 'Stress fractures of proximal diaphysis: Zone 2 injury'.)

Patients active enough to sustain a stress fracture are often reluctant to reduce their physical activity to any significant degree. These patients should be encouraged to do non-weight-bearing activity during the treatment phase. Common options include pool running, swimming, and low resistance spinning on a bicycle (while avoiding any pressure around the fracture site from the pedal).

Follow-up care — The patient is typically seen back in two to three weeks to confirm improvement in pain with initial treatment measures. Imaging is not required at this point. However, it is advisable to obtain a follow-up plain film at four to eight weeks to document healing. After four to eight weeks, and once normal daily activities can be performed without pain, the patient can gradually begin to resume higher impact activities. Follow-up visits are advisable every four to eight weeks until the patient is at (or close to) baseline function. A return of symptoms suggests recurrence of the fracture and should prompt urgent reevaluation.  

Recurrence of the stress fracture can occur if predisposing factors are not corrected, the patient resumes activities prematurely, or the volume or intensity of activity is increased too rapidly. The patient may resume exercise with 10 to 15 minutes of walking or slow running every other day for one to two weeks. If symptoms do not recur, activity may be increased by five minutes per exercise session each week. Once the patient is able to perform a slow run for 20 to 30 minutes without pain, they can select one aspect of training ‒ frequency, intensity, or distance ‒ and increase it gradually. A useful rule of thumb is to increase the selected element no more than ten percent per week. Increasing two or more elements simultaneously, or dramatically increasing any single element, raises the likelihood of recurrence. If symptoms recur at any point, volume and intensity should be reduced substantially to prevent redevelopment of the stress fracture.

The use of a custom orthotic shoe insert may benefit certain foot structures, such as a rigid or long second metatarsal, but high quality evidence supporting such interventions is lacking [3].

Fifth metatarsal stress fractures — Stress fractures of the proximal diaphysis of the fifth metatarsal, although relatively uncommon, have high rates of nonunion. They generally occur as a result of repetitive stress. We recommend referral to an orthopedist for patients with such injuries, as many will be treated with internal fixation either initially or following nonunion. These fractures are discussed in detail separately. (See "Proximal fifth metatarsal fractures", section on 'Stress fractures of proximal diaphysis: Zone 2 injury'.)

PEDIATRIC CONSIDERATIONS — As more children and adolescents participate in competitive sports and specialize in particular sports at younger ages, athletic injuries, including stress fractures, have become more common in this age group. Few studies have looked specifically at the incidence of stress fractures in patients with immature skeletal systems, but one small retrospective study reported that metatarsal stress fractures were most common in adolescent endurance athletes [14].

Overall, the management of stress fractures in children and adolescents is generally the same as for adults, with a few exceptions [14,15] Imaging plays a somewhat greater role in children and adolescents, as it is important to confirm the diagnosis and rule out other bony processes. This is especially true if symptoms persist despite a meaningful reduction in activities. During treatment, immobilization in a boot or cast is more often required in children and adolescents. This may be due to the persistence of symptoms despite a reduction in activities, or to difficulty achieving compliance with reduced activity. Attention to good nutrition, including adequate calcium intake, is of particular importance in adolescent stress fracture patients. Outcomes in adolescents appear to be similar to that in adults [14,16].

PREVENTION — The large majority of studies examining prevention of stress fractures have involved military recruits, including all 13 studies included in a systematic review of the subject [17]. This review, while emphasizing the limited quality of available studies, reported that stretching had no significant effect on injury reduction, but shock-absorbing boot inserts appeared to reduce injury rates, although practicality and comfort were a problem in some studies. A retrospective study of 2754 military recruits conducted after this review reported that shock absorbing inserts were associated with a decrease in tibial stress fractures but not metatarsal stress fractures [18]. The value of a number of general prevention measures (eg, calcium and vitamin D supplementation) and prevention measures aimed at particular risk factors (eg, relative energy deficiency in sport [ie, female athlete triad]) are assessed in a separate discussion. (See "Overview of stress fractures", section on 'Prevention'.)

In the absence of high quality evidence and studies directly applicable to the general population, clinicians must rely largely upon common sense when offering advice about strategies for preventing metatarsal stress fractures. As sudden, significant increases in training often precede stress fractures, it appears prudent to advise athletes and recreational exercisers to avoid such increases. Any sudden increase in total training volume (eg, distance run each week) or the volume of intense activity (eg, number of sprints run during a training session) should be avoided. In addition, it is likely best to avoid or limit sudden changes in training surfaces, such as moving from grass to concrete or sand. In some individuals with known anatomic or biomechanical (eg, gait) problems, orthotic inserts may be helpful. Injuries associated with minimalist shoes or barefoot running are discussed separately. (See "Running injuries of the lower extremities: Risk factors and prevention", section on 'Running barefoot or with minimalist shoes'.)  

RETURN TO SPORT AND WORK — According to a systematic review that included 901 cases of metatarsal stress fracture among recreational and competitive athletes and military recruits, the overall rate of return to sport (RTS) was 96 percent (95% CI 89-98.6) and the mean time required was 78 days (95% CI 56-101) [19]. However, reporting of RTS was not standardized in this study and so the frequency, intensity, and duration of RTS is unclear. Nonetheless, once a patient has completed treatment and rehabilitation, they should return to full activity gradually, following the principles outlined above.

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

●Epidemiology, mechanism, and risk factors – Stress fractures of the metatarsal (MT) shaft are common. MT stress fractures often develop several weeks after an abrupt increase in activity, and thus are relatively common in new military recruits. A disproportionate number of stress fractures occur in the second metatarsal shaft. Long second MTs, tight gastrocnemius and soleus muscles, pes planus (flat foot), obesity, and poor fitness are among the risk factors associated with MT stress fractures. (See 'Clinical anatomy and biomechanics' above and 'Epidemiology and risk factors' above.)

●Clinical presentation and examination findings – Patients with stress fractures of the MT shaft typically complain of gradually worsening pain in their forefoot. The pain may be poorly localized in the forefoot or focal over a particular metatarsal. The mechanism of injury typically involves repetitive stress to the forefoot, usually from running, jumping, dancing, or other repetitive weight-bearing activities. On examination, the clinician may find point tenderness over a particular metatarsal shaft (figure 2A-C). Gentle axial loading of the metatarsal head may produce pain at the fracture site. (See 'Clinical presentation and examination' above.)

●Imaging and diagnosis – Early radiographs of MT stress fractures are often unremarkable, and the diagnosis may be made on the basis of a suggestive history and examination findings. The first radiographic evidence of a stress fracture usually occurs no earlier than two to six weeks after the onset of symptoms. Narrowing of the medullary canal, cortical hypertrophy, faint lucency, and periosteal thickening develop first, followed by callus formation, sometimes as early as four to five weeks after symptom onset. Ultrasound may reveal periosteal edema prior to the appearance of abnormalities on plain radiograph. MRI and Technetium bone scan studies obtained beyond 48 to 72 hours after symptom onset are useful in early diagnosis, but often not necessary. (See 'Diagnosis' above and 'Diagnostic imaging' above.)

●Management – If recognized early, most MT stress fractures can be managed with activity reduction and basic analgesics alone for four to eight weeks. If pain persists with simple walking, a period of unloading (usually a week or two) may be helpful until walking is no longer painful. Unloading may consist of partial weight-bearing on the affected foot or non-weight-bearing. In patients with severe pain, a short-leg cast and non-weight-bearing can be used for a short period (eg, one to two weeks). Once symptoms and signs have resolved, preinjury levels of activity should be resumed gradually. (See 'Treatment' above.)

●Fifth metatarsal stress fractures at higher risk of complications – Stress fractures of the proximal shaft of the fifth metatarsal have higher rates of delayed healing and nonunion, require more prolonged immobilization, and must be closely followed. These fractures are generally referred to an orthopedist because management often involves surgical fixation. (See 'Fifth metatarsal stress fractures' above.)

●Prevention – Evidence about prevention strategies is lacking. A sensible precaution is to avoid any sudden increase in total training volume (eg, distance run each week) or the volume of intense activity (eg, number of sprints run during a training session). Transitions to more demanding surfaces (eg, from grass to concrete) or shoes (eg, from well-padded running shoes to minimalist shoes) should be made gradually. (See 'Prevention' above.)