Zone three or diaphyseal stress fractures include the proximal 1.5 cm of the diaphysis. Zone two (Jones fracture) is described as a fracture at the metaphysis-diaphyseal junction. Tuberosity avulsion fractures represent zone one (Figure 3). Proximal fifth metatarsal fractures can be classified into three zones as described by Lawrence et al and Dameron. As a result, proximal fifth metatarsal fractures were re-classified to avoid the confusing term of Jones fractures. Although the term Jones fracture was applied to the fractures in this classification, based on Torg’s description these fractures are more consistent with stress fractures. Type III (nonunion) are characterized by complete obliteration of the medullary canal by sclerotic bone with a history of repetitive trauma and recurrent symptoms (Figure 2). Type II (delayed union) are distinguished by having a previous injury or fracture with radiographic features of a widened fracture line and evidence of intramedullary sclerosis (Figure 1). Torg type I fractures are presumed to be acute fractures at a site of pre-existing stress concentration on the lateral cortex that becomes acutely disabling when they extend across the entire diaphysis. The features of acute fractures in this classification are no history of previous fracture, although previous pain or discomfort may be present. Type I (acute) fractures are characterized by a narrow fracture line and an absence of intramedullary sclerosis. Under this system the Jones fracture is divided into three types based on the radiological appearance of the fracture. This classification simplifies proximal fifth metatarsal fractures as either involving the tuberosity or the proximal diaphysis distal to the tuberosity, the latter group being called the Jones fracture. A classification system created by Torg et al is based on healing potential. A watershed area exists between the supply of the nutrient artery and the metaphyseal perforators which corresponds to the area of poor fracture healing in the clinical setting. They found that the blood supply arises from three possible sources the nutrient artery, the metaphyseal perforators, and the periosteal arteries. The blood supply of the fifth metatarsal was investigated in a cadaver model by Smith et al. The blood supply to the proximal fifth metatarsal is important in understanding troublesome fracture healing in this area. Since then there has been a focus in the literature on fractures of the proximal fifth metatarsal due to the propensity for poor healing of some fractures in this region. The Jones fracture as described by Sir Robert Jones was later defined by Stewart as a transverse fracture at the junction of the diaphysis and metaphysis without extension into the fourth and fifth intermetatarsal articulation. He described a fracture in the proximal three quarter segment of the shaft distal to the styloid. The first to describe a fracture of the proximal fifth metatarsal was Sir Robert Jones. Symptomatic nonunions of zone two and zone three fractures should be managed operatively. In the non-athlete these fractures may be managed nonoperatively however prolonged immobilization is often required and a nonunion may still result. Zone three (diaphyseal stress fractures) fractures that are Torg type I and type II should be managed with intramedullary screw fixation in the athlete. Acute and delayed union zone two fractures may be managed nonoperatively but operative management with an intramedullary screw should be considered in athletes. Operative intervention is recommended for base of the fifth metatarsal avulsion fractures (zone one) with more than three millimeters of displacement. Neck and shaft fractures with greater than ten degrees plantar angulation or three millimeters of displacement in any plane where closed reduction is insufficient require operative management. When nonoperative management is utilized improved early functional scores are associated with less rigid immobilization and a shorter period of nonweightbearing. Core tip: Nondisplaced fifth metatarsal fractures can be treated nonoperatively depending on fracture location and patient factors.
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