Causes / typical injury mechanism: Metatarsal stress fractures that classically occur in the second metatarsal of the foot are referred to as march fractures (a subtype of stress fractures). March fractures arise due to a sudden increase in repetitive weight-bearing activities that leads to microtrauma at the second metatarsal. Since the osteoblast lags behind the osteoclasts and the individual is exerting stress without rest, the bone becomes brittle and is rendered liable to fracture.

The most common location of march fractures is the second metatarsal neck as it is less flexible and under torsional force secondary to the first and second cuneiform ligamentous attachments. This leads to an increase in rigidity at the second metatarsal base, which increases the bending force with repetitive weight-bearing stress. Further, during normal gait, the first metatarsal dorsiflexes and transfers load to the rest of the metatarsal; the second metatarsal receives a greater share of this load than the rest of the metatarsals.

Classic history and presentation: March fractures were first described as a common occurrence among military recruits after long periods of marching. This stress fracture arises secondary to an unaccustomed increase in repetitive weight-bearing stress without a history of trauma. These fractures are not limited to military recruits and high-performance athletes but are also seen among runners of all levels, ballet dancers, and gymnasts. In runners, march fractures often occur in the second metatarsal's neck, while in ballet dancers, this type of stress fracture commonly occurs at the base of the second metatarsal. 

Patients presenting with march fractures usually complain of a nonlocalized, dull pain in their forefoot during exercise that is relieved with rest; eventually, the condition will progress to being painful at rest along with swelling in the dorsal forefoot region. The pain will eventually localize to the site of the second and/or third metatarsal fractures.

Prevalence: Metatarsal stress fractures account for 25% of all stress fractures. The incidence of march fractures is second to tibial stress fractures among athletes. Further, among US military personnel, the incidence is 5.6 per 1000 person-years, with higher risk among service members of Northern European descent.

• Age – Those with the highest risk are military personnel younger than 20 years or older than 40 years.
• Sex / gender – Women have a higher incidence of march fractures when compared to men.

Risk factors: Sixty percent of individuals with second metatarsal stress fractures have had a history of previous march fractures. Risk factors also include an increase in the intensity and/or volume of weight-bearing activities without sufficient rest periods. Further, patients who suddenly shifted from sedentary behavior to a rapid increase in physical activity are at a high risk of developing this type of stress fracture.

Patients diagnosed with rheumatoid arthritis, neuropathic conditions, nutritional deficiencies, amenorrhea, and anorexia nervosa are more prone to fractures under repetitive stress. Female patients are at a higher risk due to absent or abnormal menstrual periods, especially those with female athlete triad (disordered eating, amenorrhea, and osteoporosis).

This stress fracture can also occur due to extrinsic factors such as poorly fitted shoes and/or changes in the training surface. March fractures are commonly seen in patients with pes planus (flat) foot, compared to tibial stress fractures, which are more frequent in patients with pes cavus (high arch) foot.