Outer Foot Bone Fractures (5th Metatarsal Fractures): Overview

Outer Foot Bone Fractures (5th Metatarsal Fractures): Overview

This video will provide a general overview of fifth metatarsal fractures, one of the most frequently broken bones in the foot. The fifth metatarsal bone is the outermost foot bone. Fractures, or breaks, in this bone occur most often in the base of the bone, closest to the ankle. Fractures in this region of the bone were first described in 1902 by Sir Robert Jones. Sir Jones broke his own fifth metatarsal in the base of this bone. Therefore, fractures in a specific region of the base of the fifth metatarsal are called Jones fractures.

Despite the small base of the bone, it is important to understand the exact location of the fracture as it helps explain the cause of the injury and how the fracture will be treated. The fifth metatarsal bone is made up of the base, the area closest to the ankle; the shaft, or middle portion of the bone; and the head, the area closest to the toes. This video will focus on fractures that occur in the base of the bone given the frequency of fractures in this area.

The base of the bone can further be broken into 3 locations. The first is zone 1. These fractures occur at the projection at the end of the bone, called the tuberosity. Typically, the fracture seen in this area is due to a small piece of bone being pulled away by the tendon that attaches here. This is also called an avulsion fracture. In zone 2, these fractures are classified as true Jones fractures. These fractures are in a part of the bone in which blood supply can be impacted by the break. This can make healing of the bone more difficult.

Fractures in zone 3 occur furthest from the end of the base. Often these fractures are called stress fractures as they are caused by overuse or repetitive forces. Most fractures occur in zone 1, followed by zone 2 and then zone 3. Depending on the zone of injury, different risks and causes are known. Zone 1 injuries are most caused by inversion injuries, where the patient twists their foot internally and places stress on the outside of the foot.

Zone 2 injuries occur most commonly in younger patients involved in high-level activities, such as running or jumping. The patient may have predisposing foot deformities that contribute to this injury. Zone 3 injuries are often referred to as stress fractures and can occur in those who repetitively load the outside of their feet, such as in runners or dancers. These fractures are also more common in patients with high arches, females, and those with metabolic issues such as diabetes.

General recommendations in preventing these fractures may include the use of proper footwear. Also, treatment of nutritional or metabolic issues may be helpful in ensuring general bone health. With any of these fractures, patients may present with swelling, pain, bruising, or a noticeable bump over the outside of the foot. The patient may report an inability to bear weight. They may also report a twisting injury that occurred just prior to the pain.

A health care provider may ask specific questions about the patient's health history and if a specific injury occurred prior to the pain. This helps clarify if the injury occurred suddenly, as typically seen in zone 1 and 2 fractures, or if it had a more chronic onset, such as a stress fracture in zone 3. They may also do an exam to assess for underlying foot deformities that may have contributed to the injury. Multiple x-rays will be taken to look for a fracture.

More advanced imaging studies are not typically needed. However, an MRI or bone scan may be ordered to further assess for a stress fracture if x-rays are inconclusive. A CT scan may be ordered later during the healing process if delayed healing is suspected. Bloodwork may also be ordered to look for metabolic or nutritional deficiencies in this setting. Based upon the patient's history, exam, and imaging, a treatment plan will then be discussed.