The ligaments at the base of the fourth and fifth metatarsals are resistant to displacement, resulting in fracture just distal to them, at the level of the fourth and fifth intermetatarsal joints. Zone II (Jones) fractures result from an indirect, large adduction force applied to the forefoot with the ankle in plantarflexion. Zone I (tuberosity) fractures result from forces exerted on the peroneus brevis tendon or the lateral band of the plantar fascia with foot inversion. The peroneus longus courses lateral to and then plantar to the cuboid, immediately proximal to the fifth metatarsal base ( FIG 3).ĭifferent mechanisms of injury have been associated with the different fracture zones: The dorsolateral branch of the sural nerve usually lies approximately 2 to 3 mm proximal to the tuberosity and often courses at the incision site used for surgical fixation.4 The region at which these blood vessels converge corresponds to a relatively avascular watershed area, making it a tenuous area for healing.13 Metaphyseal vessels supply the tuberosity.Īn intramedullary nutrient artery enters from the medial cortex at the proximal diaphysis and flows retrograde, terminating at the metaphyseal-diaphyseal junction. Three anatomic zones of the proximal fifth metatarsal with corresponding fracture types.ĭorsal, plantar, and interosseus ligaments attach between the bases of the fourth and fifth metatarsals.īlood supply to the proximal fifth metatarsal is derived from two sources ( FIG 2):.The lateral band of the plantar fascia attaches to the plantar aspect of the fifth metatarsal base. The peroneus tertius tendon attaches on the dorsal aspect of the metaphysis. The peroneus brevis tendon inserts on the dorsolateral tuberosity. There are four main soft tissue attachments to the proximal aspect of the fifth metatarsal: Proximally, the fifth metatarsal has articulations with the cuboid and fourth metatarsal. The tuberosity is the most proximal and plantar structure of the fifth metatarsal. The fifth metatarsal consists of a head, diaphysis, metaphysis, and tuberosity. Identifying the correct zone is important because the healing characteristics and management differ for fractures occurring in each. Zone III: proximal diaphyseal stress fracture Zone II: classic “Jones fracture” at the metaphyseal-diaphyseal junction that extends into, but not beyond, the fourth and fifth intermetatarsal articulation Zone I: tuberosity avulsion fracture that may extend to the fifth metatarsal-cuboid articulation Proximal fifth metatarsal fractures are traditionally classified into three types, based on the zone or location of the fracture ( FIG 1): Of these, proximal fractures are the most common.8 The fifth metatarsal is the most frequently fractured metatarsal bone.
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