Metatarsal Stress Fracture

With an increase in public interest in physical fitness, clinical practitioners are diagnosing stress fractures with greater frequency.[1, 2, 3] First described by Aristotle in 200 BC, stress fractures were initially recorded in the medical literature in 1855 by the Prussian military physician Breithaupt, who described what is now known as a march fracture, or stress fracture of the metatarsals. See the images below.

Radiograph of the feet. This image depicts a stress fracture of the left second metatarsal with exuberant callus.

Radiograph of the left foot. This image depicts a stress fracture of the fifth metatarsal.

Bone scan of the lower extremities. This image depicts a right fifth metatarsal stress fracture.

Metatarsal stress fractures are not limited to high-level athletes or military recruits. This type of injury is seen in runners of all levels, as well as ballet dancers and gymnasts and patients with rheumatoid arthritis (RA), metabolic bone disease, and neuropathic conditions.[4, 5, 6] Metatarsal stress fractures are also seen with increasing frequency in patients who engage in aerobics activities, particularly high-impact aerobics.

Frequency

United States

The incidence of stress fractures in the general population is unknown, as virtually all literature on the subject is derived from a military population or advanced-level athletes. Stress fractures are estimated to constitute up to 16% of all injuries that are related to athletic participation; running is the cause in most of these cases. Most stress fractures (95%) involve the lower extremities, particularly the metatarsals.

A study by Waterman et al reported the incidence rate for lower extremity stress fractures in the US military (not adjusted for sex, race, age, rank, and service branch), including of the metatarsals, to be 5.69 per 1000 person-years, although tibial/fibular fractures were the most common. The highest fracture risk was found in service members under age 20 years or age 40 years or above, with the risk also higher in white service members than in black service members.[7]

The second and third metatarsals are relatively fixed in position within the foot; the first, fourth, and fifth metatarsals are relatively mobile. More stress is placed on the second and third metatarsals during ambulation; thus, these bones are at increased risk for stress fractures.

The fifth metatarsal, which is approximately 1.5 cm from the proximal pole of the bone, bears greater stress in those who oversupinate when they walk or run. The fifth metatarsal also has a diminished blood supply and, thus, a decreased ability to heal.[8, 9]

Stress fractures of the proximal fifth metatarsal must be distinguished from proximal avulsion fractures ("pseudo-Jones" fractures) and Jones fractures. The proximal avulsion fracture is usually associated with a lateral ankle strain and occurs at the insertion of the peroneus brevis tendon. The true Jones fracture is an acute fracture of the proximal diametaphyseal junction.

Queen et al investigated whether foot type (flat or normal) resulted in loading differences during four sport-specific tasks (cross-cut, side-cut, shuttle run, and landing from a simulated lay-up).[10] Of 22 healthy individuals, 12 had normal feet and 10 had flat feet, and each completed 5 trials per condition. In-shoe pressure data were collected at 50 Hz, and analyses of the entire foot and 8 regions of the foot were carried out on contact area, maximum force, and the force time integral. The investigators' findings included the following statistically significant (P< 0.05) findings[10] :

Flat feet

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• During the cross-cut task, there was an increase in medial midfoot contact area.

• During the side-cut task, an increase in contact area, force time integral, and maximum force in both the medial and lateral midfoot were demonstrated.

• During the shuttle run task, an increase in force time integral in the lateral midfoot and increases in maximum force in both the medial and lateral midfoot were present

• During the landing task, an increase in maximum force in the medial midfoot was present. However, flat feet showed a decrease in middle forefoot maximum force.

Queen et al concluded that individuals with a normal foot may have a lower risk for medial and lateral midfoot injuries such as metatarsal stress fractures. Thus, foot type should be assessed when determining an individual's risk for metatarsal stress fractures.[10]

A case-control study that included 51 NFL players reported increased risk for fifth metatarsal fractures in players with long, narrow, and straight fifth metatarsals with an adducted forefoot.[11]

Fujitaka et al studied a cohort of 273 collegiate male soccer players which included 16 who developed a fifth metatarsal stress fracture. Analysis of various history, physical, and equipment variables  suggested that stress fracture may be a result of a weak toe-grip that leads to an increase in the load applied onto the lateral side of the foot.[12]

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• Patients usually report having increased the intensity or duration of their exercise regimen.

• Initially, dull pain only occurs with exercise, then the condition progresses to pain at rest.

• Pain starts diffusely, then localizes to the site of the fracture.

• Stress fractures can be historically distinguished from a true Jones fracture, because patients with a stress mechanism as the etiology report a long history of prodromal symptoms of pain over the proximal fifth metatarsal.

• Menstrual irregularities should be explored in female patients due to a high association between female athletics, amenorrhea, and osteoporosis — otherwise known as the female athletic triad.[13, 14]

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• Inspect the affected foot for swelling, bruising, or warmth.

• Inspect both feet for a side-by-side comparison.

• Palpate the affected foot to find the point of maximal tenderness. Specifically seek to determine if the point of maximal tenderness is related to bony or soft-tissue problems.

• Inspect the patient's athletic shoes for signs of excessive supination or excessive wear under the metatarsal heads.

See the list below:

• Increased intensity, duration, or frequency of exercise

• New footwear

• Insufficient rest periods

• Continuing to train despite pain

• Osteopenia/osteoporosis

• Rheumatoid arthritis

• Neuropathic foot

• Female athletic triad

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• Due to a known association between RA and stress fractures, the clinician may consider a workup for RA, with an erythrocyte sedimentation rate (ESR) and rheumatoid panel. This workup is not routine in most patients, but it is a consideration when the clinical picture is unclear or indicates the possibility of RA.

• A workup for osteoporosis may be considered, especially in oligomenorrheic females and in patients who have (or have had) multiple stress fractures.

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• Plain-film radiography

  • Radiographs may be negative early in the process.[13, 15]

  • Stress-fracture changes may not be evident on plain films until 3 months after the onset of symptom(s).

  • Up to 50% of stress fractures are never observed on plain films.

  • Plain-film radiographs can help the physician distinguish fifth-metatarsal stress fractures from true Jones fractures. Fractures with a stress etiology show a widened fracture line, intramedullary sclerosis, and periosteal reaction (see the images below).

    Radiograph of the feet. This image depicts a stress fracture of the left second metatarsal with exuberant callus.
    Radiograph of the left foot. This image depicts a stress fracture of the fifth metatarsal.

• Bone scanning[16, 17]

  • Technetium-99 (99m Tc) diphosphonate 3-phase bone scanning has traditionally been the imaging modality of choice.

  • Bone scanning is nearly 100% sensitive for the diagnosis of stress fractures, although the specificity of this modality is considerably lower.

  • Bone scans can demonstrate stress fractures within 24-72 hours from the onset of symptom(s) (see the image below).

    Bone scan of the lower extremities. This image depicts a right fifth metatarsal stress fracture.

  • Differentiation between stress fractures and stress reactions may be determined with a bone scan.

• Magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT)[18, 19, 20] : These modalities may also be used to image stress fractures; however, MRI has become the study of choice because it has the same sensitivity as a bone scan but with a much higher specificity. Additionally, MRI does not require ionizing radiation.

• Ultrasonography

  • In a case-control study, Banal et al evaluated the sensitivity and specificity of ultrasonography to detect early stress fractures as an alternative imaging modality to MRI and bone scan scintigraphy, which are expensive or invasive, time-consuming, and poorly accessible.[21] The investigators analyzed 41 feet from 37 patients with ultrasonography and dedicated MRI. MRI detected 13 fractures in 12 patients. Ultrasonography sensitivity was 83%; specificity, 76%; positive predictive value, 59%; and negative predictive value, 92%.[21] These findings led Banal et al to conclude that when radiographs are normal, ultrasonography should be used in the diagnosis of metatarsal bone stress fractures due to its low cost, noninvasiveness, rapidity, and easy technique with good sensitivity and specificity.

Rehabilitation Program

Physical Therapy

The patient should rest from the offending activity. Immobilization is recommended for comfort, with use of a postoperative (wooden-soled) shoe or short CAM Walker (Bird and Cronin, Inc, Eagan, Minn). It is important to apply ice and elevate the foot to minimize pain and swelling. If there is marked pain or minimal evidence of healing for stress fractures of the second or third metatarsals, a short-leg walking cast can be used until there is radiographic evidence of healing.

Recreational Therapy

During the respite period from the offending activity, the patient may maintain fitness by cycling, aqua-running, or resistance training by using equipment that does not involve the affected area.

Surgical Intervention

Stress fractures of the second or third metatarsals rarely require surgical intervention. Most of these fractures heal uneventfully, and nonunion is rare. However, stress fractures of the fifth-metatarsal base are more problematic. Displacement of these fractures tends to increase with continued weight bearing. The treatment options are 2-fold as follows:

• Less-active patients should be non-weight bearing in a short-leg cast for 6-8 weeks or until there is radiographic evidence of healing. If an established nonunion develops, screw fixation and/or bone grafting may be required.[22]

• For active patients, early intramedullary screw fixation, with or without bone grafting, is often recommended.[23]

Consultations

Consult an orthopedic surgeon for fifth-metatarsal fractures or for second- or third-metatarsal fractures that do not demonstrate radiographic healing after 6 weeks.

Rehabilitation Program

Physical Therapy

During the recovery phase, the patient may progress to weight bearing as tolerated, initially in a wooden-soled shoe, and then in a comfortable shoe.

Recreational Therapy

Aqua-running, swimming, or bicycling may be continued to maintain physical fitness.

Other Treatment (Injection, manipulation, etc.)

Albisetti et al reported their experience with diagnosing and treating stress fractures at the base of the second and third metatarsals in young ballet dancers from 2005-2007.[24] Of 150 trainee ballet dancers, 19 had stress fractures of the metatarsal bone bases. All of the dancers were recommended to rest, but external shockwave therapy (ESWT) was also used in 18 and electromagnetic fields (EMF) and low-intensity ultrasonography was used in 1, with good results in each case.[24]

Albisetti advised the best approach to metatarsal stress fractures is early diagnosis with clinical examination and radiologic studies such as x-ray and MRI. The investigators also noted ESWT led to good results, with a relatively short time of rest from the patients' activities and a return to dancing without pain.[24] However, further study is warranted given the small study size and that all but one of the young dancers received ESWT.

Smith et al identify the prevalence of vitamin D deficiency in patients with a low energy fracture of the foot or ankle. The study concluded that hypovitaminosis D was common among patients with a foot or ankle injury. Patients with a low energy fracture of the foot or ankle were at particular risk for low vitamin D, especially if they smoked, were obese, or had other medical risk factors. The authors conclude that since supplementation with vitamin D (± calcium) has been shown to reduce the risk of fragility fractures and improve fracture healing, monitoring of 25-OH vitamin D and supplementation should be considered in patients with fractures.[25]

Rehabilitation Program

Physical Therapy

The patient may be allowed to gradually return to his or her sport with a slow build-up in intensity and duration, with regular rest intervals. No more than a 10% increase in intensity or duration should be allowed from week to week. Any pain recurrence should prompt a rest period, followed by resuming the activity at a lower level.

Recreational Therapy

The patient may resume running with a slow increase in duration and intensity of the workouts (ie, no more than a 10% increase in intensity or duration per week).

Surgical Intervention

Patients who continue to have painful nonunion fractures are candidates for surgical intervention.[22] A fibrous nonunion that is not painful and does not limit the patient's functional abilities may be left alone.

Consultations

An orthopedic surgeon should be consulted in cases in which there is radiographic evidence of nonunion or prolonged pain.

Analgesics may be needed in the acute phase of the treatment for metatarsal stress fractures. The patient often encounters mild to moderate pain until a period of rest and/or immobilization has occurred.

Class Summary

These agents have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but these drugs may inhibit cyclooxygenase activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

Ibuprofen (Advil, Motrin)

DOC for mild to moderate pain, if there are no contraindications. Ibuprofen inhibits inflammatory reactions and pain by inhibiting the activity of cyclooxygenase, which reduces prostaglandin synthesis.

Ketoprofen (Orudis, Actron, Oruvail)

For relief of mild to moderate pain and inflammation. Small dosages are indicated initially in patients with small body size, elderly patients, and those with renal or liver disease. Doses >75 mg do not increase therapeutic effects. Administer high doses with caution, and closely observe patient for response.

Naproxen (Aleve, Naprelan, Naprosyn, Anaprox)

For relief of mild to moderate pain; inhibits inflammatory reactions and pain by decreasing activity of cyclooxygenase, which is responsible for prostaglandin synthesis.

Flurbiprofen (Ansaid)

May inhibit cyclooxygenase enzyme, which in turn inhibits prostaglandin biosynthesis. These effects may result in analgesic, antipyretic, and anti-inflammatory activities.

Class Summary

Pain control is essential for quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who have sustained trauma or injuries.

Acetaminophen (Tylenol, Panadol, Paracetamol)

DOC for pain in patients with documented hypersensitivity to aspirin, NSAIDs, diagnosed with upper GI disease or on oral anticoagulants.

Hydrocodone bitartrate with acetaminophen (Vicodin, Lortab, Lorcet HD)

Drug combination indicated for moderate to severe pain.

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• After recovery from metatarsal stress fractures, patients may return to play when they can participate without pain.

• The intensity and duration of activities need to be increased slowly, and the patient must adhere to regular rest periods.

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• Nonunion is the primary complication of metatarsal stress fractures.

• Nonunion rates of 35-50% in fifth-metatarsal stress fractures are reported in the literature. For other metatarsal stress fractures, the nonunion rate is low.

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• Increases in sports-training demands, whether in intensity or duration, should be performed in a slow cyclical manner, and rest periods need to be built into training regimens. Use of orthotics has not been proven to decrease the incidence of metatarsal stress fractures.

• Athletes who develop pain during exercise need to decrease their training level to one that is painless, and then they can slowly resume a training regimen.

• Physicians, coaches, trainers, and parents need to be aware of metatarsal stress fractures and the symptoms. Prompt treatment can reduce morbidity and time lost from the offending sport or activity.

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• Stress fractures in the first 4 metatarsals routinely heal without complication.

• Stress fractures at the base of the fifth metatarsal have a nonunion rate of 35-50%.

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• The key to preventing stress fractures lies in the education of athletes, parents, coaches, trainers, and doctors.

• Properly selected and fitted equipment, particularly running shoes, is important in deterrence of metatarsal stress fractures.

• Training needs to be performed in a slow cyclical progression that allows the body to adapt. Adequate rest and recovery time needs to be incorporated into the participant's training regimen.

• The quality of physical activity, rather than quantity, should be stressed in any exercise program.

• The athlete, coach, trainer, and physician must recognize that exercise regimens are not "one size fits all." Tailor the training to the participant's baseline ability, previous experience, and current level of physical activity.

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education article Broken Foot.