eMedicine Specialties > Radiology > Musculoskeletal

Metatarsals, Fractures

Author: Prabhakar Rajiah, MD, MBBS, FRCR, Registrar, Department of Radiology, Central Manchester and Manchester Children's University Hospitals, UK
Coauthor(s): Shanmugam Karthikeyan, MBBS, MD, Dip Ortho, MRCS, Clinical Research Fellow in Orthopaedics, University Hospitals Coventry and Warwickshire NHS Trust, UK
Contributor Information and Disclosures

Updated: Oct 31, 2008

Introduction

Background

Fractures of the foot are common, and the metatarsals are among the bones most commonly fractured. Acute foot fractures of normal bones are usually caused by the dropping of heavy objects on the foot or as a result of stress associated with abnormal repetitive trauma. In deficient bones, insufficiency fractures may result from normal stress. (See Images 1-25 in the Multimedia Section.)

Acute fractures may be transverse, oblique, or comminuted (see Images below); they are easily recognized. Stress fractures are difficult to recognize in the early stages, when they are manifested only by a periosteal reaction. Bone scans are helpful in this situation. Recognition of fracture is crucial for guiding appropriate management and for preventing complications.^1,2

Pathophysiology

Types of metatarsal injuries

Jones and pseudo-Jones, or tennis, fractures

A Jones fracture (see Image below) is caused by inversion of the foot, which produces tension on the peroneus brevis tendon and on the lateral cord of the plantar aponeurosis.^3,4 In this type of fracture, significant displacement is absent. This type of fracture is more prone to nonunion.

Distal, or dancer's, fractures

Distal fractures, also called dancer's fractures, are caused by a rotational force resulting from axial loading with the foot in a plantigrade position.

Lisfranc dislocation

The Lisfranc joints are the tarsometatarsal joints. A Lisfranc fracture-dislocation (see Image below) is caused by falling from a height, falling down stairs, or stepping off a curb.

Mechanisms of injury are (1) rotation around a fixed forefoot (eg, falling from a horse with the foot caught in the stirrup) or (2) longitudinal compression of the foot. In this second mechanism, the metatarsal head is fixed. The weight of the body is on the hindfoot against the base of the metatarsals during rotation; these forces result in a distal dorsal dislocation of the metatarsal.

Stress fractures

Stress fractures (see Images below) are the result of abnormal stress on a normal bone. Stress fractures of the foot are also called marcher's foot because of the high incidence of occurrence in military recruits and in those who engage in heavy exercise for prolonged periods. This fracture is also common in ballet dancers, gymnasts, and athletes. Other predisposing factors include surgery, stress fractures in adjacent bones, neuropathic disease, and rheumatoid arthritis.

When a normal step is initiated, maximum force is placed on the head of the second or the third metatarsal. With increased activity, microinfarction takes place in the bones, resulting in a fracture.

Insufficiency fractures

Insufficiency fractures are the result of normal stress on a weakened bone. Such injuries are seen in people with osteoporosis; postmenopausal women are commonly affected.

Classification systems

Simple classification

Many classifications apply to fracture of the fifth metatarsal.

In a simple classification for fractures of the proximal end of the fifth metatarsal, fractures are classified as (1) those of the tuberosity and (2) those of the proximal metatarsal within 1.5 cm of the tuberosity.

Acute fractures, Jones fractures, and stress fractures may be described as (1) early fractures, (2) delayed union fractures, or (3) nonunion fractures.

Torg classification

The Torg classification is used for fractures within 1.5 cm of the metatarsal tuberosity. Type I includes fractures with sharp margins and no widening, sclerosis, periosteal reaction, or cortical hypertrophy. Type II includes fractures with widening, periosteal reaction, sclerosis, or both. Type III fractures involve widening, periosteal reaction, complete sclerosis at the fracture line, or both.

Stewart classification

The Stewart classification of fifth metatarsal fractures is as follows: type I, extra-articular fracture between the metatarsal base and diaphysis; type II, intra-articular fracture of the metatarsal base; type III, avulsion fracture of the base; type IV, comminuted fracture with intra-articular extension; and type V, partial avulsion of the metatarsal base with or without a fracture.

Zonal classification

The zonal classification, reported by Dameron, Lawrence, and Botte, categorizes metatarsal fractures by the region affected: zone 1 corresponds to the tuberosity, zone 2 corresponds to Jones fractures, and zone 3 is the diaphysis.

Mortality/Morbidity

• Early diagnosis and avoidance of weight bearing are essential to prevent the complications of metatarsal fractures.
• Complications of metatarsal fractures include nonunion (more common in Jones fractures than in other types), delayed union, malunion, secondary osteoarthritis, and reflex sympathetic dystrophy.

Race

Metatarsal fracture has no racial predilection.

Sex

Metatarsal fracture has no particular sexual predilection.

Age

Stress fractures are more common in adults involved in prolonged exercises, especially military recruits, runners, dancers, and gymnasts, than in other groups.

Anatomy

The base of the fifth metatarsal has a tuberosity that projects inferiorly in the plantar direction and attaches to the peroneus brevis tendon and the lateral band of the plantar fascia. The heads of the metatarsals articulate with the proximal phalanges of the corresponding digits.

The second metatarsal is the longest of all metatarsal bones; the first metatarsal is the shortest. Two sesamoid bones are present in the tendon of the flexor hallucis brevis, posterior to the first metatarsal bone.

Development of metatarsal bones

The primary centers of ossification of the metatarsal shaft appear by 9-10 weeks of intrauterine life. The epiphysis for the heads of the metatarsals appears by 3-4 years of postnatal life. The epiphysis at the base of the first metatarsal also appears by 3-4 years and unites by 18 years. Occasionally, the base of the fifth metatarsal has a separate secondary ossification center; this may be confused with a fracture.

Radiologic anatomy

The metatarsal bones and tarsal bones are connected by strong ligaments. Soft tissue support for the joints in the plantar aspect of foot is better than that in the dorsal aspect.

On the anteroposterior view, the lateral border of the first metatarsal should be aligned with the lateral border of the medial cuneiform. The medial border of the second metatarsal should be aligned with the medial border of the intermediate cuneiform bone.

On the oblique view, the medial and lateral border of the third metatarsal should be aligned with the medial and lateral borders of lateral cuneiform bone. The medial border of the fourth metatarsal should be aligned with the medial border of the cuboid bone. The fourth and fifth metatarsals are aligned with the cuboid bone, but the lateral part of the fifth metatarsal may project beyond the margin of the cuboid bone by up to 3 mm.

The distance between the base of the first and second metatarsals and the medial and intermediate cuneiform is more than the distance between other corresponding joints.

If a lateral image is obtained, a line drawn through the long axis of talus bone and the long axis of first metatarsal bone should be straight if there is no dislocation.

Presentation

Signs, symptoms, and treatment

In a fracture of the fifth metatarsal (see Images below), pain and tenderness are present at the base of fifth metatarsal, along with swelling and ecchymosis; in addition, the patient experiences difficulty with weight bearing. This fracture is sometime hard to differentiate from an ankle injury because the swelling can be near the lateral malleolus.

Management depends on whether the injury is an acute fracture or a stress fracture and on whether it is displaced or not.

Avulsion fractures of the tuberosity are managed conservatively with non – weight bearing casts. Jones fractures are managed according to their Torg classification: Type I fractures are managed conservatively. Type II fractures are managed conservatively or with surgery. Type III fractures are associated with more complications and are usually managed surgically.

Other problems to consider

Anatomic variants

A secondary ossification center at the base of the fifth metatarsal (apophysis) may be seen in girls 9-11 years of age and in boys 11-14 years of age (see Image below). This center is always longitudinal and parallel (not transverse) to the base of the fifth metatarsal; this may simulate a fracture. The apophysis is longitudinally oriented and is smoothly corticated; these features differentiate it from a fracture at the same location.

The os vesalianum is an accessory ossicle proximal to the base of fifth metatarsal. This is seen in the peroneus brevis tendon.

Apophysitis

This is a nonspecific inflammation of apophysis at the base of the fifth metatarsal. Apophysitis is also called Iselin disease. On clinical evaluation, pain, tenderness, and swelling are noted at the base of the fifth metatarsal. This self-limiting condition occurs in adolescents. Radiographs show an irregular apophysis but no fracture.

Stress fracture

Stress fractures are the result of abnormal stresses on a bone in which there is normal mineralization. In the foot, these fractures are common at the head of the second and third metatarsals; they frequently occur in military recruits and in marchers. The injury manifests as a thin layer of periosteal reaction. If not treated in the early stages, the periosteal reaction becomes florid. In dancers, various bones may also be involved.

Insufficiency fracture

Insufficiency fractures are commonly seen in people with osteoporosis. The bones are osteopenic, and fractures may be seen through them.

Pathologic fracture

Pathologic fractures are secondary to bone lesions, including infections and tumors, such as metastases, lymphomas, plasmacytomas, bone cysts, lipomas, and osteoblastomas.

Osteomyelitis

Osteomyelitis of the foot is common in diabetic patients. Bone scanning is the most sensitive modality for detecting osteomyelitis; the disease appears as a hot spot in the involved bone.

Radiographs are positive within 7-21 days, by which time about 50% of the bone is involved. The earliest finding is soft tissue swelling with distortion of the normal fat planes in the soft tissue. A periosteal reaction appears along the surface of the bones. Lytic destruction of the bone occurs when the disease is established. In patients with diabetes, gallium scanning or white blood cell scanning may be performed to differentiate neuropathic joints from joints affected with osteomyelitis.

Freiberg disease

Freiberg disease is osteochondrosis involving the head of the metatarsals, usually the second and occasionally the third or fourth. Clinically, patients present with pain and tenderness. Radiographs show a flattened metatarsal head with increased opacity and occasional cystic lesions. In later stages, the joint is widened, and the head is sclerotic with a thick cortex.

Neuropathic joints

In the foot, neuropathic joints are commonly caused by diabetes. Other causes include syphilis and spinal cord diseases. Clinically, the foot is swollen and usually painless, though occasionally pain is present. Radiographs show destruction of the bone, with deformity, sclerosis, osteophyte formation, loose bodies, and dislocation.

Patients with diabetes may have associated vascular calcification. Soft tissue swelling and ulcers may also occur in the diabetic foot. Frequently, neuropathic joints coexist with osteomyelitis; a white blood cell scan is indicated for differentiating these conditions.

Preferred Examination

For patients with symptoms, proper history taking is essential to identify a suggestive mechanism of injury.

Physical examination commonly reveals signs and symptoms of swelling, tenderness, warmth, ecchymosis, limitation of movements, and an inability to bear weight.

Radiography is the first and often the only investigation required for the diagnosis of fractures. Radiographs may be used to diagnose all acute fractures, dislocations, and established stress fractures (see Images 1-25).

Bone scanning is more sensitive than plain radiography; it is indicated when a stress fracture or an acute fracture is suspected and radiographs are negative. Bone scanning is not a specific investigation.

Although MRI is more sensitive than radiography and bone scanning, it is used only for the assessment of soft tissue structures and ligamentous injuries. MRI is the most sensitive technique for imaging stress fractures of the foot; MRI may depict bone marrow edema even before increased uptake is seen on bone scans.

CT scanning is useful for finding avulsion fractures and comminuted fractures and to assess for intra-articular extension.

Limitations of Techniques

Small avulsions may be missed on radiographs. In the early stages of stress fracture, radiographs may be normal, or they may show only subtle periosteal reaction, which can be easily missed. Radiography cannot be used to assess soft tissue and ligamentous disruption.

Although CT and MRI are more sensitive than radiography, they are not cost-effective and are not indicated for the diagnosis of fractures.

Although bone scanning is sensitive, some stress fractures may go undetected in the early stages.

Differential Diagnoses

Ankle, Fractures
Metatarsals, Fractures
Stress Fracture

Other Problems to Be Considered

Anatomic variants
Apophysitis
Stress fracture
Insufficiency fracture
Pathologic fractures
Osteomyelitis
Freiberg disease
Neuropathic joints

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