eMedicine Specialties > Radiology > Musculoskeletal

Metatarsals, Fractures: Imaging

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 7, 2009

Radiography

Findings

Metatarsal fractures

An acute fracture is seen as a linear lucency and a break in the cortical surface. Nondisplaced impacted fractures may appear as an opaque line; such fractures may be confirmed on a different view.

Fractures may affect any metatarsal, but the fifth metatarsal is most commonly affected. The fracture may be transverse, oblique, or comminuted. Longitudinal linear fractures are extremely rare.

The 2 most common fractures in the fifth metatarsal are a fracture at the tip of the tuberosity and a transverse fracture 1.5-2 cm from the tuberosity; the latter is called a Jones fracture. Small avulsions derived from the tip of the base of the fifth metatarsal may be seen only in the oblique projection of the ankle.⁸

Stress fractures

The head of the second metatarsal and, occasionally, the third metatarsal are commonly affected. The first metatarsal is injured in 10% of metatarsal stress fractures; such fractures involve a different kind of reaction (the endosteal variety), with liner sclerosis. Periosteal reaction is not common in this type of injury. One third of such fractures heal with only an intramedullary callus.

The base of second metatarsals may be affected in ballet dancers. The proximal aspect of the shaft of the fourth and fifth metatarsals is affected; the pattern is that of a linear lucency, which is slow to heal. Fractures in the sesamoid bones are also seen in ballet dancers.

Lisfranc fracture-dislocation

In the homolateral type, all of the metatarsals are dislocated to one side. Usually, the second to fifth metatarsals are dislocated, but occasionally, all of the metatarsals are affected. Lateral displacement is more common than medial displacement.

A divergent dislocation is medial displacement of the first metatarsal and lateral displacement of the second to fifth metatarsals. A variant of this type is an isolated medial dislocation of the first metatarsal.

Lisfranc dislocations are associated with fractures of the base of the second metatarsal, fractures of the cuboid bone, fractures of the shaft of the other metatarsal bones, dislocations of the middle and medial cuneonavicular joints, and fractures of the navicular bone. The base of the second metatarsal is relatively fixed compared with the other metatarsal bones. Therefore, it is involved in both types.

This dislocation is overlooked in as many as 20% of cases if the alignment is not carefully evaluated. Lisfranc dislocations should be suspected if a gap of more than 5 mm is present between the bases of first and second metatarsals or between the medial and middle cuneiforms.

Degree of Confidence

Radiography is sensitive in the diagnosis of acute fractures.

False Positives/Negatives

Radiographs may not show stress fractures in the early stages and in as many as 50% of patients. In addition, nondisplaced fractures may be difficult to visualize. Associated ligamentous injuries and soft tissue changes are not depicted.

Computed Tomography

Findings

CT scanning is not essential for diagnosing metatarsal fractures. If CT is planned, it should be performed in at least 2 planes: the coronal plane (perpendicular to the sole of foot) and the axial plane (parallel to the sole). With modern multisection scanners, images may be acquired in 1 plane and reconstructed in other planes with a fairly high degree of resolution.

Images are usually acquired with 5-mm sections, but 3- and 1.5-mm sections may also be acquired; the thinner sections have better resolution. Coronal images are acquired with the patient in the supine position with knees flexed and feet flat on the table. The heels of both feet are superimposed in the lateral position. Longitudinal images are acquired with the patient in the supine position with knees extended and feet perpendicular to the table.

Degree of Confidence

CT scans often depict fractures that are not visualized on plain radiographs. They are useful in evaluating the following: comminuted fractures; intra-articular extension; soft tissue trapping, including that of tendons and muscle slips; underlying pathologic lesions, if any; displacement of the fragment in the axial plane; and bony complications.

CT is more sensitive than plain radiography in the detection of stress fractures. CT findings may also show stress fractures and early degenerative changes. MRI is the only modality that is more sensitive than CT, owing to its ability to depict soft tissue and joint structures.

Magnetic Resonance Imaging

Findings

MRIs of the foot should include T1-weighted, T2-weighted, and short-tau inversion recovery (STIR) images in the axial, sagittal, and coronal planes.^{9,10,11,4,5,12,13}

The fracture line is visualized as a linear hypointensity in T1- and T2-weighted images, whereas STIR images may show hyperintensity. Edema of the bone has low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Soft tissue swelling, ligamentous injuries, plantar-late injuries are visualized better on MRIs than on other images.

MRI is useful in the assessment of fractures and dislocations, soft tissue, the plantar plate, structures of the capsule, the extent of marrow hyperemia, the exact number of bones involved, and small chip fractures.

Degree of Confidence

Although MRI is sensitive for the diagnosis of fractures, it is not required because plain radiographic findings are fairly sensitive and specific.

MRI is more sensitive than radiography and even scintigraphy in the early diagnosis of stress fractures because it shows bone marrow edema exquisitely. MRI may be used to differentiate stress fractures from early degenerative changes and early stress fractures from synovitis.

Nuclear Imaging

Findings

Bone scanning is performed with the use of technetium methylene diphosphonate. Vascular flow and delayed images are obtained.¹⁴

Acute fractures are seen as foci of increased uptake in the affected bone. However, scintigraphy is not routinely indicated for the diagnosis of acute fractures. This study is performed if the clinical findings suggest a fracture but the plain radiographs are negative.

Degree of Confidence

Bone scanning is highly sensitive; its sensitivity is surpassed only by that of MRI in certain instances. For instance, MRI and CT are more sensitive than bone scanning for evaluating stress fractures because MRI and CT can depict bone marrow edema.

Fractures become evident on bone scans before they become evident on radiographs.

False Positives/Negatives

Bone scanning is not specific. Hence, its results should not be reported in isolation. A hot spot may be seen in fractures, degenerative areas, or neoplasms. Nuclear medicine images must be correlated with plain radiographs.

• Search for CME/CE on This Topic »

• Salter-Harris Fractures (Radiology)
• Orbital Fractures (Otolaryngology and Facial Plastic Surgery)
• Unstable Pelvic Fractures (Orthopedic Surgery)
• Maxillary Fractures in Children (Otolaryngology and Facial Plastic Surgery)

• Breaks, Fractures, and Dislocations Center
• Broken Foot Overview
• Broken Foot Causes
• Broken Foot Symptoms
• Broken Foot Treatment
• Broken Toe Overview
• Crutches History

• Older Women With Visual Field Loss Have Higher Risk for Fractures
• Hip Fractures on the Decline in U.S.
• Ibuprofen May Be Effective for Outpatient Analgesia in Children With Arm Fractures

• Patterns of Skeletal Fractures in Child Abuse: Systematic Review
• Low Intensity Pulsed Ultrasonography for Fractures: Systematic Review of Randomised Controlled Trials
• Trend in Incidence of Osteoporosis-Related Fractures Among 40- to 69-Year-Old Women: Analysis of a Large Insurance Claims Database, 2000-2005

• Fracture Resource Center