Fractures of the proximal fifth metatarsal pose an important diagnostic challenge. A difference of millimeters in location can lead to a vastly different prognosis and treatment plan; a suboptimal treatment regimen can cause delayed union, reinjury, and chronic disability. Confusion surrounding fracture terminology often compounds the problem of appropriate diagnosis and management.
This topic review will discuss the diagnosis and management of the three major types of proximal fifth metatarsal fractures. Discussions of other metatarsal, foot, and ankle injuries are found elsewhere. (See "Stress fractures of the metatarsal shaft" and "Metatarsal shaft fractures".)
The fifth metatarsal is located on the lateral side of the foot (figure 1A-C). Its proximal portion is divided into three parts: the tuberosity, metaphysis, and proximal diaphysis (figure 2). The base, or proximal portion, of the fifth metatarsal articulates medially with the fourth metatarsal, while the tuberosity articulates proximally with the cuboid. Strong ligaments attach the fifth metatarsal to these two bones. Thus, range of motion is minimal. The lateral band of the plantar fascia (PF) attaches to the plantar aspect of the tuberosity. The peroneus brevis tendon (PB) attaches to the lateral aspect of the tuberosity. Tuberosity avulsion fractures are thought to result from traction by these structures during inversion injuries. (See 'Tuberosity (styloid) avulsion fractures' below.)
Variations in the blood supply to the fifth metatarsal help explain the pathophysiology of fracture healing. The tuberosity receives blood from multiple metaphyseal vessels and branches of the nutrient artery; the proximal diaphysis receives its blood supply solely from the nutrient artery (figure 3). A fracture to the proximal diaphysis is therefore more likely to disrupt the blood supply, thereby inhibiting healing and increasing the risk of nonunion .
In 1902, Sir Robert Jones described a series of acute fractures of the proximal fifth metatarsal diaphysis . Confusion over terminology has clouded the management of these fractures ever since. Some clinicians use the term "Jones Fracture" to refer specifically to acute diaphyseal fractures. Others use it indiscriminately to describe all proximal fifth metatarsal fractures. To add to the confusion, some authors separate these fractures into two groups , while others refer to three groups [4-7].