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Metatarsal shaft fractures

Metatarsal shaft fractures
Literature review current through: Jan 2024.
This topic last updated: Jun 02, 2022.

INTRODUCTION — The approach to metatarsal fractures varies according to the location and type of fracture. Fractures of the metatarsal shaft are discussed below. Proximal fractures of the fifth metatarsal, metatarsal stress fractures, and toe fractures are discussed separately. (See "Proximal fifth metatarsal fractures" and "Stress fractures of the metatarsal shaft" and "Toe fractures in adults" and "Metatarsal and toe fractures in children".)

EPIDEMIOLOGY AND RISK FACTORS — Excluding toe fractures, metatarsal fractures are the most common foot fracture [1-4]. Approximately one-third of metatarsal fractures involve the shaft or distal portion of the metatarsal. Direct blows and twisting injuries cause many of these fractures. In adults, high forces are required to fracture the first metatarsal. Hence, fractures of the first metatarsal shaft are much less common than fractures of the other metatarsal shafts.

Some populations are at higher risk for traumatic metatarsal fractures:

Older adult women with osteoporosis, decreased physical activity, or benzodiazepine use [4]

Diabetics, especially if they have had diabetes for greater than 25 years or are more active [3]

CLINICAL ANATOMY — For reference purposes, the metatarsals are numbered from first (largest) to fifth (smallest). The first metatarsal is larger than the others and more important for weight-bearing and balance (figure 1A-C and figure 2 and figure 3) [5]. Therefore, malalignment of a first metatarsal shaft fracture is not tolerated as well as malalignment of other metatarsal fractures [6].

Most fractures of a single metatarsal shaft are minimally displaced due to the splinting action of adjacent metatarsals and their abundant ligamentous and muscle attachments. The likelihood of displacement increases if multiple metatarsals are fractured or the fracture is near the metatarsal head. If displacement occurs, the metatarsal head usually displaces in a plantar direction. This is caused by the downward traction of the intrinsic muscles and flexor tendons that insert distal to the fracture.

The dorsal soft tissues of the foot are thin compared with the plantar soft tissues. They may become necrotic when crushed or rubbed repeatedly by the apex of a fractured metatarsal, leading to an open fracture.

MECHANISM OF INJURY — Most metatarsal shaft fractures are caused by direct blows or twisting forces [6]. Common mechanisms include heavy objects dropped on the foot and violent blows to the sole of the foot (as may occur during falls or auto accidents). Greater force is required to fracture the first metatarsal due to its large size [7].

CLINICAL PRESENTATION AND EXAMINATION — Patients with metatarsal fractures typically present with foot pain and have trouble walking. Dorsal swelling and ecchymosis can develop rapidly due to the foot's dependent position, if the injured area is not elevated.

Inspection — One should inspect for any signs of significant skin damage. If there is any wound near the fracture, the injury should be treated as an open fracture until proven otherwise. Crush injuries, a common cause of metatarsal fractures, may devitalize the skin. The injured skin may then necrose, leading to an open fracture.

Examination — Neurovascular injury of the foot is uncommon without significant trauma or a penetrating injury. However, a neurovascular exam should be performed and documented on every patient with a suspected metatarsal fracture.

Sequential palpation along each metatarsal can reveal the fracture site. Point tenderness over the site is the norm, but swelling may make it difficult to localize the fracture on physical examination. Furthermore, soft tissue injury may simulate the point tenderness of a fracture, especially when the injury was caused by an object dropped on the foot. Gently applying an axial load to the metatarsal heads can help differentiate fractures from soft tissue injuries. This is done by holding the toe in line with its corresponding metatarsal (ie, without angulation), and pushing the toe in toward the metatarsal. This maneuver should produce pain if the metatarsal is fractured, but not with soft tissue injury alone [8].

Assessing pain while testing plantar and dorsal flexion of the toes is helpful for differentiating a fracture from tendon injury. If a metatarsal fracture is present, direct palpation over the fracture site should produce greater pain than testing tendon function by resisting plantar and dorsiflexion.

The tarso-metatarsal (ie, Lisfranc) joint area should be palpated in all patients with foot injuries. Tenderness in this area raises the possibility of a Lisfranc injury, and referral to an orthopedist should be made. Anatomic reduction of Lisfranc injuries is critical, and inadequately treated injuries can lead to severe disability. (See "Tarsometatarsal (Lisfranc) joint complex injuries".)

Evaluation for compartment syndrome — Compartment syndrome of the foot is a rare but dangerous potential complication of metatarsal fractures, particularly fractures resulting from crush injuries or associated with the first metatarsal (ie, injuries resulting from greater force) [8]. Disproportionate pain, pallor, paresthesias, or tense swelling should prompt the clinician to consider the diagnosis. Pain with passive flexion and extension of toes is an early sign of compartment syndrome. A diminished pulse is a late finding and should not be relied upon for diagnosis. (See "Acute compartment syndrome of the extremities".)

Measurement of compartment pressure is the only reliable method to determine the presence of compartment syndrome. Pressure greater than 30 mmHg is considered diagnostic and requires emergent surgical release of the compartments [9,10].

DIAGNOSTIC IMAGING

Plain radiographs — Standard radiographic assessment includes anterior-posterior (AP) (image 1), lateral (image 2), and oblique (image 3) views of the foot [7]. AP and oblique views are often the most helpful. Shadows from overlapping metatarsals may limit the usefulness of lateral views. A modified lateral view, with the metatarsals slightly rotated to avoid overlap, may be helpful when fracture position is difficult to determine with standard views [8].

The most common metatarsal fracture pattern is oblique or transverse with minimal displacement (image 4). Multiple fractures, displacement, and comminution can be seen with high-force injury (image 5).

Occasionally, fracture lines may not be detectable on initial radiographs but become visible later (image 6). Therefore, it is prudent to manage patients as though a fracture is present if clinical findings suggest so, despite normal radiographs. In such cases, the examination and radiographs should be repeated one to two weeks after the initial injury. If point tenderness has resolved and radiographs remain normal, it is extremely unlikely the patient sustained a fracture.

Musculoskeletal ultrasound — Ultrasound is well-suited for investigating fractures in linear areas of bone, such as the diaphyseal and metaphyseal regions of the metatarsals.

Musculoskeletal ultrasound (MSK US) examination of the foot is best performed with the patient seated on the examination table, their knee flexed to 90 degrees, and the plantar surface of the foot resting on the examination table. A high-frequency transducer of at least 10 mHz is typically used. A small footprint (hockey stick) linear probe (picture 1) makes examination of the foot and metatarsals easier. MSK US examination of the metatarsals involves a standard two-position examination (longitudinal [ie, sagittal] and transverse views). Initially, the probe is placed on the dorsum of the foot at the distal metatarsophalangeal (MCP) joint, and then moved proximally. Images are obtained in the longitudinal and transverse planes. The cortex of each metatarsal is examined carefully for any discontinuity in the hyperechoic surface consistent with a fracture. Cortical discontinuities as small as 1 mm can be identified with high-resolution transducers and may enable visualization of fractures that would be missed with standard radiographs [11]. Occasionally, hematoma, edema, or ligamentous disruption may be seen in association with the injury.

Studies of MSK US report sensitivities of 97 percent and specificities of 100 percent for fifth metatarsal fractures [12,13], and overall, ultrasound is reliable for identifying lower extremity fractures. However, while ultrasound can be effective for diagnosing metatarsal fractures, plain radiographs may still be needed to determine angulation and rotation.

INDICATIONS FOR ORTHOPEDIC CONSULTATION OR REFERRAL — Immediate surgical referral is required for all open fractures and for all fractures with associated vascular compromise or nerve injury. Early referral is also recommended for fractures with significant skin damage [8]. Other indications for referral include the following [7,8,14]:

Fractures of multiple metatarsals (image 5 and image 6)

Displaced fractures near the metatarsal head (image 7)

Intraarticular fractures (image 8)

Displaced fractures of the first metatarsal, even if displacement is minimal, because anatomic position is necessary for optimal weight-bearing function

Unstable fractures of the first metatarsal, judged by clinical findings or stress radiographs

Concurrent injuries of other structures, including injury of the tarso-metatarsal (ie, Lisfranc) ligament complex and fractures of other foot or ankle bones (See "Tarsometatarsal (Lisfranc) joint complex injuries".)

Widely cited guidelines suggest that isolated shaft fractures with greater than 3 to 4 mm displacement in the dorsal/plantar plain or angulation greater than 10 degrees should be reduced [5,7,15-17]. This recommendation does not appear to be supported by any definitive data, and studies exist that question this approach [5,18]. As an example, in a study of 31 ballet dancers with fifth metatarsal shaft fractures, all of whom were treated nonoperatively (even the five patients with displaced fractures), all were able to return to high-level ballet dancing [18].

Nevertheless, reduction or referral appears wise in such cases since this is the current standard of care, and there are insufficient data to refute the traditional approach.

INITIAL TREATMENT

Minimally and nondisplaced fractures — If the fracture is minimally or nondisplaced and conditions requiring emergency referral have been excluded, initial treatment includes immobilization in a posterior splint and non-weight-bearing with a follow-up visit in three to five days [8]. The injury should be iced and elevated higher than the level of the heart for the first 24 hours. (See "Patient education: Cast and splint care (Beyond the Basics)".)

Displaced fractures — Metatarsal fractures that are displaced laterally or medially usually do well without correction. Metatarsal fractures displaced more than 3 to 4 mm in a dorsal or plantar direction or with angulation greater than 10 degrees in this plane should probably be reduced or referred (see 'Indications for orthopedic consultation or referral' above). Fractures with lesser degrees of dorsal and plantar displacement can be treated as nondisplaced fractures.

Reduction can frequently be achieved under local anesthesia using either a regional block (particularly useful in patients with multiple metatarsal fractures) or a hematoma block. The latter involves direct injection of local anesthetic into the hematoma that forms at the fracture site.

Once there is adequate anesthesia, reduction can be achieved by placing the toes in Chinese finger traps and allowing gravity to accomplish the reduction. Applying light weights or manual traction to the distal tibia is sometimes helpful. The reduction should be maintained by a molded, bivalved, non-weight-bearing cast, and postreduction radiographs should be obtained to confirm proper alignment. Referral or consultation with an orthopedist is recommended if the clinician is uncertain about the necessity of reduction or uncomfortable about performing the reduction, or if adequate alignment is not maintained by the reduction and immobilization measures described here.

Again, the injury should be iced and elevated higher than the level of the heart for the first 24 hours, while keeping the cast dry.

FOLLOW-UP CARE

Minimally and nondisplaced fractures — Nondisplaced and minimally displaced metatarsal shaft fractures heal well without cast immobilization in most cases [19]. Treatment after the first follow-up visit generally consists of a firm, supportive shoe and progressive weight-bearing as tolerated. A post-operative (post-op) shoe (picture 2) is advised if the patient does not have suitable shoes or the foot is too swollen to fit in supportive shoes.

A well-molded, short-leg walking cast may be necessary if the patient has significant pain while bearing minimal weight. Generally, a cast is placed several days after the injury when swelling is reduced. Radiographs should be repeated one week after the injury (or during the initial follow-up visit, if this takes place five days or longer after the injury) to assure the fracture remains non-displaced. After two to three weeks, the cast may be replaced with a firm shoe or post-op shoe for two to three additional weeks.

Most fractures are considered "healed" when callus is visible on radiographs and point tenderness has resolved, which usually occurs by six weeks in adults. Complete healing requires many months. Radiographs should be repeated four to six weeks after the injury to document healing [7,8]. If callus is seen and the fracture has minimal to no tenderness, protection can be discontinued and regular activities gradually resumed. At this point, the patient will need ankle range of motion and calf strengthening/stretching exercises to speed full recovery of function.

Displaced fractures — Displaced fractures of the metatarsal shafts are usually placed in a bivalved cast acutely. (See 'Initial treatment' above.) Follow-up the next day is recommended to assure that additional swelling has not made the cast too tight. The patient should return for subsequent follow-up approximately one week after the injury. Radiographs should be obtained at that time in the cast, if it has not become loose. If fracture position remains acceptable, the cast may be reinforced and continued as a non-weight-bearing cast for two to three more weeks. The cast should be replaced if it has become loose. We recommend that radiographs be obtained after placement in the new cast to assure adequate fracture alignment is maintained.

The patient should be reevaluated with radiographs at three to four weeks after the injury. If the fracture is still in good position, a short-leg walking cast should be applied for three to four weeks with progressive weight-bearing followed by range of motion and strengthening/stretching exercises upon cast removal. Orthopedic consultation is recommended if fracture position is lost at any time during follow-up [8].

COMPLICATIONS — Most metatarsal shaft fractures heal well when treated appropriately, but complications do occur:

Arterial injury and compartment syndrome may develop acutely in metatarsal shaft fractures and may lead to loss of the foot or ischemic contracture. (See 'Evaluation for compartment syndrome' above.)

Open fractures may lead to osteomyelitis.

Malunion of any shaft fracture can lead to metatarsalgia, while malunion of the first metatarsal often leads to impaired weight-bearing ability.

Uncorrected plantar deviation of the metatarsal head may lead to an intractable plantar keratosis, while uncorrected dorsal angulation can lead to dorsal corns [7]. (See "Overview of benign lesions of the skin", section on 'Calluses and corns'.)

Complex regional pain syndrome may complicate metatarsal shaft fractures. (See "Complex regional pain syndrome in adults: Pathogenesis, clinical manifestations, and diagnosis".)

RETURN TO SPORT OR WORK — Patients may be able to return to work within one week of injury, provided their job does not require much walking, standing, or use of the foot. Otherwise, they should not work until symptoms allow them to perform their job comfortably and safely. Toe and ankle range of motion exercises and gentle calf stretching are generally begun three to four weeks after injury (or one to two days after cast removal, if a cast was placed). Strengthening exercises and gentle walking follow. Patients may engage in fast walking or gentle running once the fracture demonstrates healing and walking is no longer painful. Activities may be gradually advanced as tolerated from there.

A study of ballet dancers with fifth metatarsal shaft fractures found that patients with non-displaced fractures returned most rapidly to dancing (seven weeks on average) [18]. Patients with minimally displaced fractures returned in an average of 15 weeks, and those with displaced fractures returned in an average of 23 weeks.

ADDITIONAL INFORMATION — Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:

(See "General principles of fracture management: Bone healing and fracture description".)

(See "General principles of fracture management: Fracture patterns and description in children".)

(See "General principles of definitive fracture management".)

(See "General principles of acute fracture management".)

(See "General principles of fracture management: Early and late complications".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Lower extremity (excluding hip) fractures in adults" and "Society guideline links: Acute pain management".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

Basics topics (see "Patient education: How to use crutches (The Basics)")

SUMMARY AND RECOMMENDATIONS

Epidemiology – Excluding toe fractures, metatarsal fractures are the most common foot fracture. Approximately one-third of metatarsal fractures involve the shaft or distal portion of the metatarsal. (See 'Epidemiology and risk factors' above.)

Clinical presentation and physical examination – Careful assessment of neurovascular status is important. Pay close attention to the possibility of compartment syndrome with crush injuries and fractures of the first metatarsal. (See 'Clinical presentation and examination' above.)

The status of the skin near the fracture site should be assessed, especially in severe crush injuries, looking for open wounds, tenting, or significant injury predisposing to necrosis.

The Lisfranc ligament complex (tarso-metatarsal joint area) should be palpated in all patients with a suspected foot fracture. Injury to this ligament can be disabling, and tenderness in this area should prompt referral.

Management and indications for orthopedic referral – The first metatarsal plays a crucial role in foot function, and anatomic reduction is the goal in the management of such fractures. Displaced or unstable first metatarsal fractures are one of several criteria mandating referral to an orthopedist. (See 'Initial treatment' above and 'Indications for orthopedic consultation or referral' above.)

Most traumatic fractures of the shafts of metatarsals 2 to 5 can be managed without casting or reduction, provided there is minimal displacement in the dorsal or plantar direction. Metatarsal fractures displaced more than 3 to 4 mm in a dorsal or plantar direction or with angulation greater than 10 degrees in this plane should be reduced in most cases or referred to an orthopedist.

Referral to an orthopedist is warranted if loss of fracture reduction or significant fracture displacement occurs at any time during follow-up. (See 'Follow-up care' above.)

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