Proximal fractures of the fifth metatarsal are most common in young male athletes. These fractures are devastating to athletes because they are slow to heal and have a high potential for delayed union, nonunion, and refracture. 4,9,[14][15][16][17][18][19]26,28 These fractures can be acute, stress, or combined acute/stress fractures of the proximal portion of the fifth metatarsal. The Jones fracture 4,8 was first described by Jones in 1902 13 and involves the proximal third of the fifth metatarsal, distal to the insertion of the fibularis (peroneus) brevis tendon, 1.5 cm from the tuberosity of the fifth metatarsal (figure 1). 5,7,8,16,23 Jones described the mechanism of injury in vivid terms: "so powerful are the ligaments that dislocation is rare. It is obviously easier to break the bone than to dislocate it." 13 The fifth metatarsal is subjected to 3-point bending (figure 1) when the foot lands in a relatively inverted position. Forces are imposed at the proximal end of the fifth metatarsal by the ground reaction force and soft tissues such as the fibularis brevis, lateral bands of the plantar fascia, and ligamentous/capsular tissue between the cuboid and the base of the fifth metatarsal. Force is also imposed by the ground reaction force at the distal end of the metatarsal as a result of the foot being in a relatively inverted position. Finally, the base of the fourth metatarsal applies a force in response to the previously described forces, completing the 3-point bending stress that may produce a stress fracture in response to cumulative fatigue, an acute fracture following sufficiently high-magnitude loading, or a combination of the two. Weight bearing that occurs with the foot in an inverted position, therefore, tends to promote the t studY design: Preintervention and postintervention, repeated-measures experimental design.t oBJectives: The objective was to investigate the effects of foot orthoses with medial arch support on ankle inversion angle and plantar forces and pressures on the fifth metatarsal during landing for a basketball lay-up and during the stance phase of a shuttle run.t Background: Proximal fractures of the fifth metatarsal, specifically the Jones fracture, are common in sports. Wearing foot orthoses with medial arch support could increase the ankle inversion angle and the plantar forces and pressure on the fifth metatarsal that may increase the risk for fifth metatarsal fracture.t MetHods and Measures: Three-dimensional (3-D) videographic, force plate, and in-shoe plantar force and pressure data were collected during landing after a basketball lay-up and during the stance phase of a shuttle run with and without foot orthoses with medial arch support for 14 male subjects. Two-way ANOVAs with repeated measures were performed to compare ankle inversion angle, maximum forces, and pressure on the fifth metatarsal head and base between conditions and between tasks.t results: The maximum ankle inversion angle and maximum plantar force and pressure on the base of the fifth metatarsal during both ...
