Continuing Education Activity

March fractures (metatarsal stress fractures) were first described in 1855 when the term was coined for the foot pain and swelling experienced by Prussian soldiers on long marches. March fractures are caused by repetitive stress. Intrinsic patient and extrinsic environmental risk factors can both contribute to the development of these fractures. Diagnosis is based on a combination of historical features, physical evaluation, and imaging studies. These fractures are typically managed conservatively but can be complicated by nonunion. In such instances, surgical fixation may be warranted. This activity describes the pathophysiology, evaluation, and management of march fractures and highlights the role of the interprofessional team in the care of affected patients.

Objectives:

• Identify the etiology of metatarsal stress fractures.
• Describe the presentation of a patient with a metatarsal stress fracture.
• Review the treatment and management options available for metatarsal stress fractures.
• Explain interprofessional team strategies for improving care coordination and communication to advance the prevention and treatment of metatarsal stress fractures and improve patient outcomes.

Introduction

March fractures (metatarsal stress fractures) were first described in 1855, termed after the foot pain and swelling experienced by Prussian soldiers on long marches.[1] March fractures are metatarsal fractures caused by repetitive stress. Intrinsic patient and extrinsic environmental risk factors can both contribute to the development of these fractures. A combination of historical features and physical evaluation with imaging can help make the diagnosis, although prodromal symptoms are common before evidence of a stress fracture is seen on plain radiographs. Typically, radiographic evidence may be negative for 2 to 4 weeks after the onset of symptoms. These stress fractures are typically managed conservatively but can be complicated by nonunion. In such instances, surgical fixation may be warranted.

Etiology

March fractures are metatarsal stress fractures, most commonly second and third metatarsal fractures caused by an overuse injury. The repetitive impact on the metatarsals with weight-bearing exercises causes microfractures, which consolidate into stress fractures and, therefore, are not a result of a single traumatic event[2]

The most common location of metatarsal stress fractures is the second metatarsal neck, as it is less flexible and prone to torsional forces, given its strong ligamentous attachment to the 1 and 2 cuneiforms. In addition, the second metatarsal is the longest of the metatarsals, subjected to the most force.[3]

Epidemiology

March fractures occur commonly with sports and sudden increases in physical activity over 6 to 8 weeks. Metatarsal stress fractures are common in athletes and the military, accounting for 25% of all stress fractures.[2] Overall data suggest that females have a higher incidence of march fractures than men. In addition, those with prior stress fractures are more likely to develop another. Sixty percent of patients with a stress fracture will have had a previous one.[4]

Pathophysiology

Common in new military recruits, a pervading theory is that osteoblastic activity lags behind osteoclastic activity during initial increases of exercise stress, leading to an increased incidence of stress fractures. March fractures occur secondary to bone fatigue or bone insufficiency. Bone fatigue occurs when a normal bone is unable to resist excessive mechanical demands. Bone insufficiency occurs when normal strain occurs on abnormal bone. Intrinsic risk factors such as nutritional deficiencies such as vitamin D or calcium increase the risk of these fractures. In addition, extrinsic risk factors such as the training type or shoe type can also contribute to an increased risk of metatarsal stress fractures.[1]

Classification System[3][5]

Kaeding and Miller’s 5-Tier Grading System

Grade of Stress Fracture/Radiographic Finding

1. Asymptomatic radiographic findings
2. Pain with no fracture on imaging
3. Nondisplaced fracture on imaging
4. Displaced fracture on imaging
5. Sclerotic nonunion on imaging

Biomechanics

There are two types of cortical stress fracture that have been previously described. The two types depend on whether the stress is localized to the tensile or compression side of the bone that is under stress. Compression stress fractures correspond to a fracture line occurring on the side of the bone that is concave in shape. These fractures run parallel to the bone axis. In comparison, tensile stress fractures appear on the convex side of the stressed bone, and these fracture lines develop perpendicular to the bone axis. Compression stress fractures tend to be less common than their traction counterparts.[6]

History and Physical

During an interview, patients indicate that there is an inciting activity or exercise subjecting the patient to repetitive stress. Activity-related, insidious onset of pain at the site of fracture is often elicited from the history. Pain may improve transiently with rest but increases again with activity. Pain often is described as dull and aching. It is important to obtain a thorough medical history with particular attention to potential intrinsic risk factors. This may include an interview on a patient’s diet, endocrine disorders, and menstrual history in female patients.

Physical examination consists of palpation of the pain site, eliciting boney tenderness. If the fracture is in the proximity of a joint, the joint motion will aggravate the pain. Patients may have a limping gait with weight bearing.

Evaluation

March fractures are diagnosed based on historical clues, physical examination, and confirmed with diagnostic imaging. Plain radiographs are the initial imaging modality of choice. However, plain radiographs have a high rate of false negatives for metatarsal stress fractures early on and may not demonstrate fractures until 2 to 4 weeks after the onset of pain.[7][8] While an apparent fracture through the metatarsal may be visible on a radiograph, subtle periosteal reactions and blurring of the cortex may be the only clues of a stress fracture. More mature fractures may demonstrate callus formation or cortical lucency.[1]

Occult, suspected fractures not visible on plain radiographs can be imaged using three-phase bone scans with technetium-99 or magnetic resonance imaging (MRI).[1][2] Both advanced imaging modalities have been proven to be sensitive to these fractures up to 24 hours after the onset of pain. While bone scans are considered sensitive but not specific, MRI is both sensitive and specific for metatarsal stress fractures.[3][4][8]

Lastly, thorough testing of the patient’s intrinsic risk factors may be needed. For example, measuring serum 25(OH), vitamin D concentration can be considered in those suspected of nutritional deficiencies.[3]

Treatment / Management

In most cases, analgesia and rest are the only steps needed for metatarsal stress fracture healing. Acetaminophen and ice are implemented for pain and swelling. The effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on fracture healing remains contested.[1]

Immobilization is often unnecessary, and a stiff-soled orthopedic boot or walking boot may be used for 4 to 8 weeks. Weight-bearing is allowed as long as the patient is pain-free. Thus, exercise may resume with lower impact exercises such as swimming, cycling, or deep water running. The exception to this treatment is areas at higher risk for nonunion, consisting of the base of the fifth metatarsal and the neck of the second metatarsal. Special consideration should be given to pain elicited in these areas for advanced imaging if radiographs are negative. In addition, if a fracture at these sites is present, non-weight bearing status can be achieved with crutches and casting. Additionally, a referral to an orthopedic surgeon should be placed in cases of nonunion that may need surgical fixation.[2][3][4]

Modifiable risk factors should be treated. Nutritional deficiencies such as low levels of vitamin D, calcium, or calories should be addressed by ensuring adequate intake and supplementation as needed. Environmental changes should be considered. Shock-absorbing insoles for shoes or boots can distribute force during weight-bearing exercises. The type of training activity, surface, and intensity can be adjusted.[3][8]

A graded return to activity should be employed as a march fracture heals. When the patient is fully weight-bearing and pain-free with low-intensity exercise, the patient gradually increases their exercise intensity by 10% every week to avoid further stress fractures.[3]

Prevention of march fractures includes stretching with gradual increments in exercise intensity and duration to avoid abrupt changes in stress. In addition, correcting predisposing biomechanical conditions such as gait training and arch supports can be beneficial.

Differential Diagnosis

DIfferentials for march fracture include the following conditions:

• Acute metatarsal fracture

• Acute sesamoid fracture

• Common peroneal nerve injury

• Hallux rigidus

• Jones fracture

• Posterior tibial nerve injury

• Proximal fifth metatarsal avulsion fracture

• Saphenous nerve injury

• Sesamoid stress fracture

• Sural nerve injury

Complications

Nonunion is a complication of march fractures with symptoms of chronic pain, swelling, or instability. In such cases, surgery with intramedullary nailing may be warranted. Post-operatively, healing can be arduous, sometimes taking months to years.[3]

Enhancing Healthcare Team Outcomes

March fractures are best managed by an interprofessional team that also includes nurses and physical therapists. The key is to prevent them in the first place. Patients need to be educated on the importance of stretching prior to exercise. In addition, correcting predisposing biomechanical conditions such as gait training and arch supports can be beneficial.

The outcomes for most patients are good, but recurrence is not uncommon. Failure to diagnose a march fracture can lead to non-union and moderate disability.