The second metatarsal bone is one of the five long bones located in the forefoot, positioned between the first metatarsal and the third metatarsal. It connects the tarsal bones of the ankle and midfoot to the second toe. Situated near the center of the foot’s structure, this bone extends from the midfoot to the ball of the foot. Its location makes it a significant structural component of the second ray, helping to form the transverse and longitudinal arches of the foot.
Specific Role in Foot Mechanics
The structure of the second metatarsal makes it a relatively fixed and stable column within the foot. It is often the longest of the five metatarsal bones, and its connection to the tarsal bones is less flexible than its neighbors. This lack of mobility means the bone acts as a rigid anchor point, distributing forces across the forefoot during movement.
During the gait cycle, particularly the “toe-off” phase when the foot pushes off the ground to propel the body forward, this bone bears a considerable amount of force. It helps stabilize the foot as weight shifts from the heel to the ball of the foot and finally to the toes. Variations in foot architecture, such as a longer second toe, can increase the stress placed on this bone.
Key Conditions Affecting the Bone
The second metatarsal’s role in weight-bearing, combined with its rigid structure, makes it highly susceptible to certain overuse injuries. A common example is a stress fracture, often historically referred to as a “March fracture” because of its prevalence in military recruits. This condition is characterized by tiny cracks in the bone, resulting from repetitive strain where bone breakdown outpaces the body’s natural rebuilding process.
Symptoms of a stress fracture typically involve gradually worsening pain on the top of the foot that intensifies with high-impact activities. Swelling or tenderness may also be present in the forefoot. This injury commonly occurs in individuals who suddenly increase the intensity or duration of physical activity without adequate rest.
Another distinct condition that frequently affects this specific bone is Freiberg’s Infraction, a form of avascular necrosis. This involves the death of bone tissue in the head of the metatarsal due to an insufficient blood supply. While the exact cause is unclear, it is thought to be related to repetitive physical stress or micro-trauma, often presenting in adolescents, particularly young women.
Freiberg’s Infraction causes pain in the ball of the foot, stiffness, and limited mobility in the toe joint. Patients may describe the sensation as feeling like they are walking on a hard object. This disease process compromises the bone’s structure, potentially leading to a flattening of the metatarsal head.
Diagnostic Procedures and Initial Care
Diagnosis of a second metatarsal injury usually begins with a physical examination and imaging studies. X-rays are the standard first step, but they may not show a stress fracture in its early stages because the tiny cracks are not immediately visible. If initial X-rays are inconclusive, follow-up imaging may be ordered if symptoms strongly suggest a fracture.
More sensitive tests, such as a bone scan or Magnetic Resonance Imaging (MRI), can confirm the diagnosis by revealing early bone stress or soft tissue damage. For Freiberg’s Infraction, X-rays may eventually show a characteristic flattening of the metatarsal head, but an MRI provides a more detailed view of the bone tissue viability.
Initial care for common injuries like stress fractures focuses on immediately reducing stress on the bone. This involves a period of rest and avoiding the activity that caused the pain. A healthcare provider may recommend a walking boot or cast to immobilize the foot and prevent weight-bearing. Pain management is achieved using ice to reduce swelling and over-the-counter pain relievers.