Proximal fifth metatarsal fractures

INTRODUCTION — Fractures of the proximal fifth metatarsal pose an important diagnostic challenge. A difference of millimeters in location may lead to a vastly different prognosis and treatment plan; a suboptimal treatment regimen can cause delayed union, reinjury, and chronic pain and disability. Confusion surrounding fracture terminology often compounds the problem of appropriate diagnosis and management.

This topic will discuss the diagnosis and management of the major types of proximal fifth metatarsal fractures. Other metatarsal and foot injuries are reviewed separately.

●Metatarsal fractures (see "Stress fractures of the metatarsal shaft" and "Metatarsal shaft fractures" and "Tarsometatarsal (Lisfranc) joint complex injuries")

●Tarsal fractures (see "Cuboid and cuneiform fractures" and "Non-stress fractures of the tarsal (foot) navicular" and "Stress fractures of the tarsal (foot) navicular")

●Foot pain (see "Overview of foot anatomy and biomechanics and assessment of foot pain in adults" and "Evaluation, diagnosis, and select management of common causes of midfoot pain in adults" and "Evaluation, diagnosis, and select management of common causes of forefoot pain in adults")

CLINICAL ANATOMY — The fifth metatarsal is located on the lateral side of the foot (figure 1A-C). Its proximal portion is divided into three parts: the tuberosity (or styloid), intermetatarsal zone (metaphysis), and proximal diaphysis. The tuberosity or styloid (we use "tuberosity") is the most proximal end of the fifth metatarsal and articulates with the cuboid. The intermetatarsal zone or metaphysis (we use "intermetatarsal zone") lies just distal to the tuberosity and articulates medially with the fourth metatarsal. We designate the proximal diaphysis as a distinct zone just distal to the intermetatarsal zone.

Strong ligaments attach the fifth metatarsal to the cuboid and fourth metatarsal. Thus, the fifth metatarsal range of motion is minimal. The lateral band of the plantar fascia attaches to the plantar aspect of the tuberosity. The peroneus brevis tendon attaches to the lateral aspect of the tuberosity (figure 2). Tuberosity avulsion fractures are thought to result from traction by these structures during forceful foot (not ankle) inversion.

Variations in the blood supply to the fifth metatarsal help to explain the pathophysiology of fracture healing. The tuberosity receives blood from multiple metaphyseal vessels and branches of the nutrient artery, while the intermetatarsal zone and proximal diaphysis depend solely on the nutrient artery (figure 3). Fractures distal to the tuberosity may disrupt the nutrient artery’s retrograde blood flow, thereby inhibiting healing and increasing the risk for delayed union or nonunion of intermetatarsal zone fractures [1].

HOW TO CLASSIFY AND DISTINGUISH AMONG FRACTURE TYPES — In 1902, Sir Robert Jones described a series of acute fractures of the proximal fifth metatarsal [2]. Confusion over terminology has clouded the management of these fractures ever since. Some clinicians use the eponym "Jones fracture" to refer specifically to fractures extending into the intermetatarsal joint. Others apply it more broadly to describe all fractures of the diaphysis, regardless of the exact location or whether a stress or acute fracture is present. To add to the confusion, some authors separate these fractures into two groups [3], while others refer to three groups [4-7].

The classification of proximal fifth metatarsal fractures that we prefer divides them into two groups:

●Zone 1 injuries involve a fracture of the tuberosity, the most proximal portion of the fifth metatarsal. Zone 1 extends distally from the most proximal aspect of the bone to the proximal border of the intermetatarsal region. The blood supply to this region is robust, and therefore, the risk of nonunion is relatively low (image 1 and figure 3). (See 'Clinical anatomy' above.)

●Zone 2 injuries are fractures involving the intermetatarsal zone and/or the proximal diaphysis. These fractures extend transversely towards the intermetatarsal joint (between the bases of fourth and fifth metatarsal) and/or into the proximal diaphysis just distal to the intermetatarsal joint. Zone 2 injuries may involve acute or stress fractures, but all are at higher risk of nonunion from possible disruption of the more tenuous blood flow provided by the nutrient artery (image 2 and image 3 and figure 3).

This scheme is not foolproof, and researchers continue to propose new classification schemes with the goal of providing better guidance about treatment. Some fractures occur in borderline locations, making it difficult to determine the fracture type [8]. In such cases, close follow-up and reassessment are essential. Clinicians must also consider the mechanism and history when determining the most likely fracture type. If a stress fracture is present, the Torg classification scheme (table 1) may help guide treatment decisions. (See 'Stress fractures of proximal diaphysis: Zone 2 injury' below.)

The revised classification scheme outlined above is more consistent with current management and aligns more accurately with prognosis [9]. In previous schemes, transverse fractures just distal to the intermetatarsal zone (the so-called "metaphyseal-diaphyseal junction") were viewed as a distinct fracture type, but they are likely a variant of the current zone 2 injury and should be treated as such. In addition, the revised scheme more clearly reflects the bone's blood supply (figure 2), separating the tuberosity region with a rich blood supply and generally good prognosis following injury from the intermetatarsal zone and proximal diaphysis, which are dependent largely on the nutrient artery and prone to poor healing should blood flow be disrupted (table 2 and figure 4).

TUBEROSITY FRACTURE: ZONE 1 INJURY — The tuberosity is the most proximal portion of the fifth metatarsal (figure 2). It protrudes in the lateral and plantar planes. Fractures of the tuberosity are among the most common lower extremity fractures. They generally heal without difficulty and are readily managed by primary care clinicians.

Mechanism of injury — Tuberosity fractures are considered avulsion-type fractures and occur during forced inversion of the hindfoot and plantarflexion of the forefoot [10]. This may occur when a basketball player lands awkwardly from a jump or a runner inverts their foot (not ankle) while running on an uneven surface.

The cause of the injury was once thought to be forceful contraction of the peroneus brevis during hindfoot inversion [11]. Further studies suggested the mechanism of injury to be contracture of the lateral band of the plantar fascia [12]. Subsequently, studies using magnetic resonance imaging (MRI) and computed tomography (CT) concluded that both structures are likely involved [10,13].

Clinical presentation and examination — Because tuberosity fractures occur with foot inversion and symptoms are often mild, patients frequently present to primary care settings complaining of a sprained ankle. The key to detecting this injury is to apply the Ottawa ankle rules systematically to all patients with lateral foot pain following a possible ankle inversion injury. These rules, which include palpation of the proximal fifth metatarsal, have been shown to detect nearly all tuberosity fractures while simultaneously reducing unnecessary foot radiographs (figure 5) [14]. The Ottawa ankle rules are summarized in the following figure (figure 5) and discussed more thoroughly separately. (See "Ankle sprain in adults: Evaluation and diagnosis", section on 'Ottawa ankle rules'.)

Patient history should include the onset, quality, and duration of symptoms as well as the mechanism of injury. Physical examination should include inspection, palpation for the point of maximal tenderness, palpation of sites recommended in the Ottawa ankle rules, and neurovascular assessment. The clinician should evaluate adjacent structures, including the other metatarsals, tarsals, and ankle. If a tuberosity fracture is present, the clinician will elicit tenderness at the base of the metatarsal and may note swelling and ecchymosis at the site of maximal tenderness. Walking may be possible but painful.

Diagnostic imaging — If a tuberosity fracture is suspected, standard radiographs of the foot should be obtained: anteroposterior, anteroposterior oblique, and lateral views (image 4 and image 5 and image 6). In one small observational study, a significant percentage of tuberosity avulsion fractures were not visible on standard foot radiographs but were seen on anteroposterior and oblique views of the ankle [15]. Hence, it is reasonable to obtain ankle radiographs if a tuberosity fracture is strongly suspected but initial foot radiographs are negative.

When initial plain radiographs do not show a fracture but clinical suspicion for a fracture at the base of the fifth metatarsal remains high, we generally presume an injury is present and treat conservatively for two to three weeks (see 'Initial treatment' below) before reimaging with plain radiographs. If repeat radiographs still do not demonstrate a fracture but clinical concern persists, MRI may be performed.

Radiographs typically reveal a sharp, well-defined radiolucency perpendicular to the long axis of the fifth metatarsal. The fracture may be extra-articular or intra-articular (ie, extending into the cuboid-metatarsal joint (image 1)). Occasionally, the medial end of the fracture line is not clearly visible and one must classify the fracture based on the direction of the line. Fractures extending into or towards the intermetatarsal joint or proximal diaphysis are considered zone 2 injuries and have a different prognosis and treatment, which are discussed below. (See 'Intermetatarsal and proximal diaphysis fractures: Zone 2 injuries' below.)

Ultrasound may have adequate sensitivity for identifying an injury at the base of the fifth metatarsal, and this may be helpful in some settings (eg, sideline assessment at an athletic event) [16]. However, few clinical studies have been performed, and ultrasound may not be sufficiently precise to determine the location of a fracture (ie, zone 1 or 2) or the presence of displacement or associated injuries. Pending further study, ultrasound should not be relied upon to assess or manage fractures of the proximal fifth metatarsal.

Plain radiographs of the foot often reveal two normal structures that may be confused with tuberosity fractures: accessory bones and growth plates. Small accessory bones (or ossicles), such as the os peroneum, may lie near the base of the fifth metatarsal (figure 1A-C). These are typically rounded, smooth surfaced, and relatively far from the tuberosity (compared with a fracture fragment); and they possess a uniform cortical appearance around the entire perimeter. Familiarity with accessory bone appearance and location helps to prevent fracture misidentification (image 1). Chronically symptomatic ossicles are not common but may occasionally require excision for definitive pain relief [17].

In children, depending on their skeletal maturity, an apophysis (growth center associated with a tendon insertion) is often seen at the tuberosity. The apophysis is oriented longitudinally (or parallel) to the long axis of the fifth metatarsal and has smooth, corticated edges. Some classify injury at the apophysis as an "apophyseal nonunion" fracture. However, "apophysitis" (inflammation of the apophysis) rather than fracture may be the cause of acute or chronic pain in children. This self-limiting condition, sometimes referred to as Iselin disease (image 7), typically resolves with rest and activity modification. It is discussed in greater detail separately. (See "Forefoot and midfoot pain in the active child or skeletally immature adolescent: Overview of causes", section on 'Iselin disease (fifth metatarsal traction apophysitis)'.)

Indications for orthopedic consultation or referral

Emergency referral — Emergency referral is rarely required for tuberosity fractures (zone 1 injuries). The rare fracture that is open or associated with a neurologic or vascular deficit requires immediate surgical referral.

General indications — Orthopedic referral is recommended for any of the following findings, which may require surgical intervention:

●Displacement greater than 3 mm (image 8 and image 9)

●Step-off greater than 1 to 2 mm at the articular surface with the cuboid

●Presence of associated fractures

●Symptomatic nonunion (image 10)

When clinicians are uncertain about the presence of the listed criteria, surgical referral is reasonable.

Other indications for surgical intervention remain a subject of debate. We believe that consultation with an orthopedist or podiatrist is reasonable for nondisplaced tuberosity fractures if the fragment includes more than approximately 60 percent of the metatarsal-cuboid joint surface, especially for patients who are athletes, heavy laborers, or otherwise highly active. In a case series of 95 patients, fractures with larger avulsion fragments (corresponding to more than about 60 percent of the metatarsal-cuboid joint surface) had a higher rate of displacement during treatment [18]. However, these findings have yet to be confirmed in other studies, and the clinical significance of secondary displacement of smaller fracture fragments remains unclear.

Initial treatment — Nondisplaced tuberosity fractures require only symptomatic treatment [4]. Standard initial therapy for acute musculoskeletal injury may be used. Rest, ice, elevation of the foot above the heart level, and acetaminophen help reduce symptoms acutely. Commercially available walking boots (picture 1) provide adequate support and protection as well as some pain relief. If such a boot is not an option, the combination of a soft compression bandage and a hard-soled postoperative shoe (picture 2) may be used.

At the time of the initial evaluation, clinicians should ensure that the walking boot or postoperative shoe fits well. Pneumatic boots are ideal, as they offer secure protection and comfort. If a postoperative shoe is used, the heel should not slip out the back and the foot should not plantarflex easily. Initially, weightbearing in a walking boot may be painful and crutches may be needed to allow partial- or non-weightbearing ambulation. Once the patient can ambulate in the boot (or postoperative shoe) with minimal pain and no limp, crutches may be discontinued. A gradual transition is then made to full weightbearing in the walking boot. Rarely is casting necessary. Regardless of treatment, weightbearing is allowed as tolerated.

The relatively benign nature of tuberosity fractures and the simple approach to management are supported by several studies [19-21]. In one trial, 60 patients were randomly assigned to either a soft dressing or short-leg cast. Decreased recuperation time (33 versus 46 days) was needed in the soft dressing group, but otherwise, there were no significant differences in outcome [19]. In another trial involving 96 patients randomly assigned to treatment in a hard-soled shoe or a short-leg cast, no clinically or statistically significant differences were noted in pain or patient satisfaction, and there were no cases of nonunion [21]. The time to return to preinjury activity was shorter in the hard-soled shoe group (average 37 versus 43 days in the cast group).

The authors strongly advise clinicians to warn patients at the initial visit that follow-up radiographs of the fracture obtained two to four weeks after the injury often demonstrate a "widened" fracture line. This finding is due to early osteoclast activity that occurs prior to osteoblastic healing. Typically, this widening does not represent displacement, and the patient can be reassured that this appearance reflects normal healing. However, it is easier to convince the patient of this at the follow-up visit if they were forewarned. Subsequent imaging at six to ten weeks will show the expected healing.

Follow-up care — We recommend an initial follow-up visit one to two weeks after diagnosis and every three to four weeks thereafter until healing is achieved and full function returns. Most patients with tuberosity fractures are asymptomatic within three weeks with radiographic union in eight weeks [6]. Follow-up radiographs should be obtained approximately eight weeks after injury to document healing. Persistence of symptoms beyond this period raises the possibility of delayed union or nonunion and warrants re-evaluation, including continued serial imaging.

While most tuberosity fractures demonstrate healing on plain radiographs within two months, healing may be delayed in certain populations, including older adults, noncompliant patients, and those with comorbidities such as diabetes or peripheral vascular disease. Such patients should be followed with monthly radiographs. However, if pain is well controlled and continued healing (ie, fracture callus) is demonstrated, these patients may continue with conservative treatment. Surgical referral may be necessary if healing stalls or pain persists. Physical therapy may help patients who are slow to recover function.

A 2021 systematic review of nine studies of treatments for zone I fractures included two randomized trials, of which one reported that patients managed with functional therapy returned to work significantly sooner than those treated with immobilization (11 versus 28 days), with otherwise similar outcomes [22]. The nonrandomized studies reported a faster return to full function (33 versus 46 days) with early functional therapy.

Complications — Complications are unusual, although a prospective observational study that included 62 tuberosity fractures found that 25 percent of patients continued to experience some pain one year after injury [23]. A minority of patients have prolonged discomfort, which is more common if the fracture was displaced or a step-off at the articular surface was present.

Return to work or sports — Once healed, patients may gradually resume their usual activities as tolerated, using their symptoms as a guide. Because tuberosity fractures are not prone to refracture, the patient may increase activity less gradually than with other proximal fifth metatarsal fractures. Patients with physically demanding jobs may need to wait longer until the fracture is healed sufficiently and strength is regained before resuming work.

We occasionally suggest that patients insert an off-the-shelf orthotic in their athletic or work shoe if they are trying to return to play or work soon after radiographic healing becomes apparent. These inserts provide support and reduce pain and swelling during the early return to activity. They may be particularly useful in patients with significant pes planus (flat foot) or whose gait demonstrates pronounced pronation.

An ankle brace may be used as patients gradually return to walking without a supportive boot or as needed for athletes returning to play. However, fifth metatarsal injuries do not occur from ankle inversion, so bracing the ankle should not be offered as support for recovery from the injury; bracing does support an ankle that may be deconditioned from immobilization in a treatment boot.

To prevent possible ankle injury, physical therapy may be more appropriate for the athlete returning to training or the older adult trying to regain confidence with activities of daily living. Additional interventions to help prevent ankle injury include wearing supportive shoes and exercises for ankle mobility and balance. (See "Ankle sprain in adults: Management", section on 'Prevention'.)

INTERMETATARSAL AND PROXIMAL DIAPHYSIS FRACTURES: ZONE 2 INJURIES — Intermetatarsal and proximal diaphysis fractures occur just distal to the site of tuberosity fractures. The medial end of the fracture line extends into the intermetatarsal joint space or just distally. It is important to differentiate these injuries from tuberosity fractures, as the prognosis is substantially worse. Stress fractures too may occur in this region but are managed differently and discussed separately. (See 'Stress fractures of proximal diaphysis: Zone 2 injury' below.)

Anatomic terminology — Several terms have been used to describe the area where these fractures occur, including "metaphyseal-diaphyseal junction," "proximal diaphysis," and "junction of the metaphysis and diaphysis." We prefer the following terminology:

●Intermetatarsal zone is the portion of the metaphysis encompassing the area of articulation between the fifth and fourth metatarsals.

●Proximal diaphysis is the area just distal to the intermetatarsal region but not extending into the middle third of the diaphysis.

●Intermetatarsal and proximal diaphysis refers to the combination of both these areas. Fractures in this region are referred to as zone 2 injuries. (See 'How to classify and distinguish among fracture types' above.)

Mechanism of injury — Acute fractures in this region do not occur during ankle and foot inversion. Some researchers claim they are caused by vertical or mediolateral forces exerted on the base of the fifth metatarsal while the heel is raised and the foot is plantarflexed [24]. Others ascribe these fractures to a significant adduction force applied to the forefoot while the ankle is in plantarflexion [4]. Practically speaking, athletes can sustain this injury during any sudden, forceful change in direction performed with the heel off the ground, such as during football, basketball, or tennis matches.

In contrast, stress fractures result from chronic microtrauma, predominantly in younger athletes. In this region, they occur much less often than acute fractures. (See 'Stress fractures of proximal diaphysis: Zone 2 injury' below.)

Clinical presentation and examination — Patients with intermetatarsal and proximal diaphysis fractures describe pain on the lateral side of the foot anterior to the ankle and have difficulty bearing weight. Edema and ecchymosis are usually present. Abrupt onset of pain following a distinct injury suggests an acute fracture. Occasionally, the symptoms of a stress fracture will suddenly worsen after trauma or an acute stress (eg, dramatic increase in training intensity). In such cases, the clinician may be misled into suspecting an acute fracture rather than a stress fracture. Inquiring about persistent pain prior to the acute event may help to distinguish between the two.

Patient history should include the onset, quality, and duration of symptoms as well as the mechanism of injury. Physical examination should include inspection, palpation for the point of maximal tenderness, palpation of sites recommended in the Ottawa ankle rules (figure 5), and neurovascular assessment. The clinician should evaluate adjacent structures including the other metatarsals, tarsals, and ankle. With all foot and ankle injuries, clinicians should systematically apply the Ottawa rules to avoid missed fractures and unnecessary radiographs (figure 5).

Diagnostic imaging — Standard plain radiographs of the foot (anteroposterior, oblique, and lateral) are the initial studies to be obtained. These images reveal a fracture line that extends into the articulation between the bases of the fourth and fifth metatarsals (image 2) or just distal to this point. With acute fractures, the fracture line is sharp and surrounding bone appears normal (image 11), but with subacute fractures (injury two to four weeks old), the fracture line may be widened, especially toward the lateral portion of the metatarsal.

It is sometimes difficult to distinguish between acute and stress fractures on plain radiographs, and treatment may differ. In such cases, MRI may be needed to establish the diagnosis. The radiographic characteristics of stress fractures are described below. (See 'Diagnostic imaging' below.)

Ultrasound may have adequate sensitivity for identifying an injury at the base of the fifth metatarsal, and this may be helpful in some settings (eg, sideline assessment at athletic event) [16]. However, the accuracy of ultrasound for diagnosing intermetatarsal and proximal diaphysis fractures is not well studied. While it may be useful for identifying a fracture, ultrasound may not be sufficiently precise to determine its exact location (ie, zone 1 or 2) or the presence of displacement or associated injuries. Pending further study, ultrasound should not be relied upon to assess or manage these high-risk fractures.

Indications for orthopedic consultation or referral

Emergency referral — Emergency referral is rarely required. The rare fracture that is open or associated with a neurologic or vascular deficit requires immediate surgical referral.

General indications — Given the higher nonunion rates for these fractures and evidence about the effectiveness of operative repair, we believe that surgical referral should be made for high-level athletes and offered to all active patients (eg, heavy laborers, recreational athletes). Not all referred patients will choose surgical repair, but referral enables them to discuss that approach.

In addition, displaced fractures in this region generally require internal fixation, and any patient with a fracture involving greater than 2 mm of displacement or associated injuries (including additional tarsal or metatarsal fractures) should be referred to an orthopedist or podiatrist [4]. (See 'Surgery versus conservative therapy' below.)

For nonelite athletes and other active patients, age and level of physical activity play a role in determining whether to pursue conservative or surgical management. The clinician should be prepared to discuss the relative benefits and risks of each approach with the patient. (See 'Surgery versus conservative therapy' below.)

Initial treatment — Initial treatment consists of immobilization in a posterior splint or walking boot (picture 1) with a follow-up reassessment in one to two weeks. Most patients are not able to bear weight immediately following the injury due to pain and require crutches. Icing and elevation of the injured foot above the level of the heart are recommended to minimize swelling. Appropriate analgesics should be provided.

Surgery versus conservative therapy

High-level athletes — Professional and elite amateur athletes (eg, members of Olympic or national teams, Division I college athletes in the United States) should be referred to a surgeon, as many will opt for surgical fixation. Surgical treatment is associated with significantly earlier return to play and lower rates of nonunion. As an example, a 2021 meta-analysis of 22 studies (one randomized trial) limited to athletes with acute fractures (n = 646) at the intermetatarsal area or proximal diaphysis reported that surgical management significantly increased the return to play rate (98 percent surgery versus 71 percent conservative) and reduced the time to return to play (9.6 weeks post-surgery versus 13.1 weeks conservative) [25]. The union rate among athletes treated surgically was 97.3 percent (95% CI 95.1-99.4) compared with 71.4 percent for those managed conservatively (95% CI 49.1-93.7). These findings are similar to those reported in other studies [9,26-28].

Lower-demand athletes and nonathletes — Nearly all recent surgical studies of acute and chronic intermetatarsal and proximal diaphyseal fractures have involved high-level athletes, and thus, the potential benefits and risks of surgery in lower-demand athletes (eg distance hikers), heavy laborers, and nonathletes are not well defined. Nevertheless, given the relatively high rates of nonunion associated with these injuries and the successful outcomes described in high-demand athletes, we believe it is appropriate to offer surgical fixation to these patients as well.

Patients who choose surgery accept the small risk of associated complications (primarily infection and painful hardware) in return for a greater likelihood of successful fracture healing and earlier return to activity. Conversely, before initiating conservative treatment, the patient must understand the relatively high risk of nonunion and the possibility of a subsequent need for surgery if nonoperative treatment fails.

Higher-risk patients — For patients at higher risk for surgical complications (eg, patients with diabetes or peripheral vascular disease), conservative management may be more appropriate. If conservative management is chosen, it is performed as described below. Little evidence is available to guide practice in higher-risk patients. A small observational study from 1996 reported that open reduction and internal fixation (ORIF) with autologous bone grafting resulted in radiographic union of intermetatarsal zone fractures in patients with diabetes initially treated with immediate or delayed ORIF without bone grafting [29]. The authors suggested that an initial trial of conservative management did not have deleterious effects on the secondary surgery.

Nonoperative management

Initial treatment — Patients being managed nonoperatively are placed in a controlled ankle movement (CAM) walking boot (picture 1) and permitted to bear weight as tolerated, provided ambulation is pain free. If a CAM walking boot is not available, a walking cast or robust splint that can be customized to endure several weeks of ambulation is an acceptable alternative. Initially, partial weightbearing as tolerated with crutches may be necessary due to pain. When not ambulating, patients should keep the injured foot above the heart level as much as possible [30,31].

A properly fitted boot provides protection, support, and comfort. Multiple studies demonstrate that fracture healing is not inhibited by early, protected weightbearing in a properly fitted CAM walking boot [30-34]. The authors have noted improvements in ankle range of motion and tolerance for bearing weight among patients managed in a well-fitted boot. With uncomplicated fractures, gentle ankle mobility exercises may aid functional recovery and reduce pain. In addition, the risk of "disuse osteoporosis," which may affect patients managed with a lengthy period of nonweightbearing, is avoided.

Follow-up care — In general, follow-up visits to re-examine the foot and review new plain radiographs to assess fracture healing are scheduled every three to four weeks [30]. These appointments may be discontinued when patients achieve pain-free ambulation and radiographs show complete healing. If there is concern that displacement may have occurred since the initial radiographs (eg, due to additional trauma or noncompliance with treatment), plain radiographs may be obtained sooner, one to two weeks after injury, to ensure the fracture remains nondisplaced. It is important to counsel the patient at the initial visit that plain radiographs of the fracture taken two to four weeks after the injury commonly demonstrate a widened fracture gap, but that this likely does not represent displacement. The reasons for this are discussed above. (See 'Initial treatment' above.)

Throughout the recovery period, the patient should gently perform stretches of their calf muscles and ankle range-of-motion exercises, ideally several times each day. If pain recurs at the fracture site, activity should be decreased. The patient should be re-evaluated if pain becomes severe or persists despite decreased activity.

Once clinical and radiographic healing are evident, the patient should begin progressive weightbearing in a good supportive shoe and nonweightbearing exercises to restore normal foot and ankle function. Formal physical therapy may help older adults and other patients at higher risk for falls to regain their strength, stamina, and function.

Healing may mean different things to different patients. For zone 2 fractures in particular, we distinguish between activities of daily living healing, which precedes activity healing.

●Activities of daily living healing – Patients with activities of daily living healing have minimal or no tenderness, no pain with weightbearing, and signs of callus on plain radiographs. All these criteria should be present for the clinician to consider allowing ambulation without a boot. Should pain recur or escalate after the boot is discontinued, we recommend resuming use of the boot until the patient is pain free.

●Activity healing – Patients with activity healing perform all activities of daily living without pain and demonstrate complete cortical healing on plain radiographs. Even when these criteria are met, clinicians should emphasize the importance of increasing activity gradually over the course of several weeks to months based on the patient's prior baseline activity level.

The timeframe for each type of healing varies widely depending upon patient age, body mass index, comorbidities, and activity demands. For young, healthy athletes, activity healing may be achieved in two to three months. Older adults with significant comorbidities may need two to three months, or even longer, just to achieve activities of daily living healing.

Once they have achieved activities of daily living healing, older adults and other patients at higher risk for falls may benefit from formal physical therapy to regain their strength, stamina, and function. Athletes may require formal physical therapy for appropriate strength programs and for supervision to ensure they do not advance too quickly and risk reinjury.

If formal physical therapy is not available, simple exercises may be useful, including ankle mobility exercises emphasizing end range of motion, "writing the alphabet" with the foot, and moderate resistance exercises using an elastic exercise band. These exercises help to maintain or regain ankle mobility and strength. As the patient becomes able to bear weight, basic single-leg balancing, as pain and ability permit, promotes balance and proprioception.

The clinician may discharge the patient from care once foot and ankle function have regained baseline function without pain and radiographs demonstrate complete healing. The patient should be instructed to return for any problems, especially recurrent pain, which may indicate refracture.

Delayed union can occur, especially in older patients, those with comorbidities, and fractures that extend into the intermetatarsal joint. Referral to an orthopedist or podiatrist is recommended for delayed union, as these injuries may require surgery or other interventions. After three months of persistent nonunion without evidence of callus formation, some clinicians use external bone stimulators in hopes of promoting healing, but there are no controlled studies demonstrating the effectiveness of these devices.

Complications — Primary complications include delayed union and nonunion. In uncomplicated cases, some patients have persistent pain after healing. Shoe modification or surgical referral may be required if this occurs. (See "General principles of fracture management: Early and late complications".)

Return to work or sports — Once complete radiographic healing and pain-free weightbearing have been achieved, the progression to more demanding activities should be gradual to avoid reinjury. Light running may begin once walking is painless and fluid. As a general rule, we suggest that training increase by no more than 10 percent per week. Cross-training with cycling and swimming can help the patient regain cardiovascular fitness while minimizing impact on the foot. The higher physical demands of heavy labor or competitive athletics may warrant an even more gradual progression to the preinjury level of activity.

STRESS FRACTURES OF PROXIMAL DIAPHYSIS: ZONE 2 INJURY — Stress fractures of the proximal diaphysis are caused by chronic, repetitive microtrauma and occur predominantly in younger athletes. They are much less common than acute fractures in this portion of the bone [4]. Despite their infrequency, stress fractures deserve special attention because of their marked propensity for delayed union and nonunion compared with other proximal fifth metatarsal fractures and stress fractures of other metatarsals [4]. This tendency for poor healing is attributed to prolonged disruption of the nutrient artery, the main blood supply to the area (figure 3).

Clinical presentation and examination — Patients with a stress fracture usually experience a prodrome of pain up to several months prior to presentation, which is characteristically more intense during exercise or other weightbearing activity. Tenderness is present over the fracture site. Edema and ecchymosis may be present, but absence of these signs should not deter the clinician from considering the diagnosis.

Patient history should include the onset, quality, and duration of symptoms as well as the mechanism of injury. Physical examination should include inspection, palpation for the point of maximal tenderness, palpation of sites recommended in the Ottawa ankle rules (figure 5), and neurovascular assessment. The clinician should evaluate adjacent structures including the other metatarsals, tarsals, and ankle. With all foot and ankle injuries, clinicians should systematically apply the Ottawa ankle rules to avoid missed fractures and unnecessary radiographs (figure 5).

Diagnostic imaging — Standard radiographs of the foot (anteroposterior, oblique, and lateral) should be obtained. Although stress fractures in this region are not as common as acute fractures, when they do occur, they are most commonly seen in the proximal diaphysis, just distal to the intermetatarsal joint between the bases of the fourth and fifth metatarsal (figure 2 and figure 4 and image 3 and image 12).

Radiographic findings vary depending on the stage of the stress fracture. In contrast to acute fractures, where the fracture line is sharp and the surrounding bone appears normal (image 2), the bone surrounding stress fractures appears abnormal. Cortical thickening is seen with an early stress fracture (Torg type I) (image 3), while older stress fractures manifest a widened fracture line and partial (Torg type II) (image 12) or complete (Torg type III) obliteration of the medullary canal.

A classification system for predicting outcome and planning treatment has been developed (table 2 and table 1) [35]. Misclassification can lead to inappropriate treatment, potentially causing delayed healing.

In some cases, plain radiographs may reveal no evidence of stress fracture even weeks to months after the onset of pain. For patients in whom clinical suspicion remains high, but radiographs are unrevealing, we suggest the patient substantially limit activity and that plain radiographs be repeated in two weeks. We reserve MRI for highly competitive athletes who are unwilling to reduce activity levels and patients in whom clinical suspicion remains high but follow-up radiographs at two weeks again fail to reveal any evidence of fracture.

Indications for orthopedic consultation or referral

Emergency referral — Because of the chronic nature of these injuries, emergency referral is rarely, if ever, needed. Open fractures warrant immediate surgical referral.

General indications — All Torg type II and III fractures warrant surgical referral (table 1 and image 12), as the large majority will be treated with surgical fixation. Some patients with a type II fracture may be candidates for conservative management, but this determination should be made with the input of the consulting orthopedist or podiatrist.

Nonoperative management may be preferred initially for many Torg type I fractures, but early operative fixation is a viable option, especially for highly active patients and heavy laborers; thus, surgical referral is reasonable for nearly all patients with stress fractures of the proximal fifth metatarsal [6,7,36-38].

For high-level athletes, operative repair of Torg type I fractures frequently enables an earlier return to play. Studies of stress fracture management, most retrospective and of limited quality, have looked primarily at high-level athletes, and thus, it is difficult to extrapolate the best approach for the general population [37-39].

Should the patient choose a conservative approach, orthopedic referral is indicated if treatment results in nonunion (eg, radiograph shows sclerotic changes without callus or union). The time at which nonunion becomes apparent can vary, but surgical consultation is prudent if the patient continues to experience pain and radiographic healing has failed to progress on serial monthly radiographs after three to six months of nonoperative management. Referral may be unnecessary if the patient is not a good surgical candidate, has regained function and has no pain, or does not engage in activity that places great stress on the foot.

Initial treatment — The ideal candidate for conservative management is a nonathlete with a Torg type I fracture who wants to avoid surgery. The patient must be made aware that treatment may be lengthy (possibly several months) and that nonunion may still occur. Rest, ice, elevation of the foot above the heart level, and acetaminophen help to reduce symptoms acutely.

Unless acute trauma occurred just before presentation, the risk of compartment syndrome is minimal, and the patient can usually be placed in a controlled ankle movement (CAM) boot (picture 1). The patient may require a short period, usually one to two weeks, of nonweightbearing until pain improves. If a CAM walking boot is not available, a walking cast or robust splint that can be customized to endure several weeks of ambulation is an acceptable alternative. Initially, partial weightbearing as tolerated with crutches may be necessary due to pain. As symptoms improve over the course of days to weeks, gradual progress to weightbearing in the boot as tolerated is encouraged, but only if gait is normal (ie, not inhibited by pain).

Follow-up care — The patient should be seen monthly to assess clinical and radiographic improvement. Once healing is clearly present (eg, tenderness resolved, well-established callus present across fracture site), the patient can be weaned from the boot to a good supportive shoe and may begin gradual, progressive weightbearing and range-of-motion exercises. The simple mobility exercises described above for acute fractures are suitable for patients with stress fractures (see 'Follow-up care' above). Physical therapy referral is often helpful. It is important to caution the patient that advancing activities too rapidly may cause a recurrence of pain or impair fracture healing.

If the patient experiences pain reminiscent of the stress fracture, activities should be curtailed immediately and the foot reevaluated. If healing is not evident on serial plain radiographs after three to six months, referral to a surgeon is warranted.

Complications — Nonunion and delayed union are the most common complications. Chronic discomfort following treatment and prolonged recovery may also occur. (See "General principles of fracture management: Early and late complications".)

Return to work or sports — Patients may begin a gradual return to full activity once the following criteria are met:

●Radiographic healing is evident

●Full ankle mobility is restored

●Activities of daily living are performed pain free

Light running may begin once walking is painless and fluid. As a general rule, we suggest that training increase by no more than 10 percent per week. Cross-training with cycling and swimming can help the patient regain cardiovascular fitness while minimizing impact on the foot. High-impact and high-stress activities, such as jumping and pivoting, should be reserved for the final stages of rehabilitation and only after the patient has achieved approximately 75 percent of their preinjury level of fitness. Throughout the rehabilitation process, the patient should remain vigilant for symptoms suggesting a recurrence of the stress fracture (eg, reappearance of focal pain or tenderness at the fracture site) and seek immediate reevaluation should they develop.

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".)

SUMMARY AND RECOMMENDATIONS

●Overview of fracture types and key distinctions – Three different fracture types occur in the proximal fifth metatarsal: tuberosity avulsion, acute diaphyseal, and stress diaphyseal. Prognosis and treatment differ substantially among them. The most difficult distinction is between acute fractures and stress fractures of the proximal diaphysis. Acute fractures lack a prodrome of chronic symptoms, occur abruptly, and demonstrate a sharp fracture line with normal surrounding bone on initial radiographs. Stress fractures generally present after a prodrome of chronic pain and have a characteristic radiographic appearance based on their age.

●Tuberosity avulsion fractures

•Mechanism – Avulsion fractures occur in the tuberosity (styloid), proximal to the intermetatarsal joint (figure 4). They occur with forced inversion of the foot and ankle while they are in plantarflexion (eg, basketball player lands awkwardly or runner inverts their ankle on an uneven surface). (See 'Mechanism of injury' above.)

•Clinical presentation – Because tuberosity fractures occur with ankle inversion and symptoms are often mild, patients frequently present to primary care settings complaining of a "sprained ankle." The key to detecting the fracture is to apply the Ottawa ankle rules systematically to all patients with lateral foot pain following an inversion injury (figure 5). (See 'Clinical presentation and examination' above.)

•Diagnostic imaging – Standard foot radiographs should be obtained; ankle radiographs sometimes reveal fractures not seen on foot films. Radiographs typically reveal a radiolucency perpendicular to the long axis of the fifth metatarsal. The fracture may extend into the cuboid-metatarsal articulation or lie proximal to this joint. Tuberosity fractures do not extend into the joint between the fourth and fifth metatarsal; if this is the case, an acute diaphyseal fracture is present. (See 'Diagnostic imaging' above.)

•Indications for surgical referral – Orthopedic referral is recommended when there is displacement, a step-off of more than 1 to 2 mm on the articular surface with the cuboid, other associated fractures, or symptomatic nonunion. (See 'Indications for orthopedic consultation or referral' above.)

•Nonoperative treatment – Nondisplaced avulsion fractures require only symptomatic treatment. In most cases, this can be accomplished with a hard-soled shoe, but occasionally, more definitive immobilization (eg, casting) is required for pain control. (See 'Initial treatment' above.)

Follow-up is performed initially one week after diagnosis and every two to three weeks thereafter until healing is achieved and full function returns. Most patients are asymptomatic or nearly so within three weeks, with radiographic union in eight weeks. Follow-up radiographs should be obtained approximately eight weeks after injury to document healing. (See 'Follow-up care' above.)

●Acute fractures of the intermetatarsal region and proximal diaphysis

•Clinical presentation – Acute fractures of the proximal diaphysis occur at the level of the inter-metatarsal joint (figure 4). Patients describe pain on the lateral side of the foot anterior to the ankle, have difficulty bearing weight, and may have surrounding edema and ecchymosis. Abrupt onset of pain following a distinct injury suggests an acute fracture. Occasionally, a stress fracture suddenly worsens after an acute stress, which may mislead a clinician into diagnosing an acute fracture. Inquiring about persistent pain prior to the acute event helps to avoid this pitfall. (See 'Clinical presentation and examination' above.)

•Diagnostic imaging – The fracture line of acute fifth metatarsal diaphyseal fractures typically extends into or towards the articulation between the bases of the fourth and fifth metatarsals. (See 'Diagnostic imaging' above.)

•Indications for surgical referral – Fractures displaced more than 2 mm warrant surgical referral. For nondisplaced fractures, nonoperative treatment is common and often effective, but surgery may yield lower rates of nonunion. Thus, surgical referral should be made for all high-level athletes and offered to all active patients (eg, heavy laborers, recreational athletes). (See 'Indications for orthopedic consultation or referral' above.)

•Management – Acute fractures of the proximal fifth metatarsal heal poorly compared with similar fractures of other metatarsals. Before initiating nonoperative treatment, the clinician and patient should thoroughly discuss treatment options, including early referral for possible operative repair.

For patients selecting nonoperative management, we suggest treatment with immobilization in a walking boot or short-leg cast for approximately six to eight weeks (Grade 2C). Healing times can vary widely depending on patient characteristics. Delayed union and nonunion may occur even with expert conservative treatment and excellent patient compliance. A suggested treatment and rehabilitation schedule is described in the text. (See 'Surgery versus conservative therapy' above and 'Nonoperative management' above.)

●Stress fractures of the proximal diaphysis

•Mechanism – Stress fractures of the fifth metatarsal result from chronic and repetitive microtrauma, predominantly in younger athletes. They occur much less often than acute diaphyseal and tuberosity avulsion fractures but have a much greater propensity for delayed union and nonunion.

•Clinical presentation – Patients usually experience a prodrome of increasing pain up to several months prior to presentation. Pain is characteristically more intense during exercise or other weightbearing activity. Tenderness is present over the fracture site. Local edema and ecchymosis may be present. (See 'Clinical presentation and examination' above.)

•Diagnostic imaging – Stress fractures are most commonly seen just distal to the intermetatarsal articulation between the bases of the fourth and fifth metatarsal (figure 4). They may occur more proximally and be confused with acute fractures. Radiographic findings vary depending on the stage of the stress fracture (table 1). Misclassification can lead to inappropriate treatment. (See 'Diagnostic imaging' above.)

•Management and indications for surgical referral – We obtain surgical referral for all Torg grade II and III stress fractures. While we prefer to obtain surgical referral for Torg grade I stress fractures as well, for patients with such injuries who are eager to avoid surgery and able to tolerate 20 weeks of nonweightbearing immobilization, nonoperative treatment is reasonable. (See 'Indications for orthopedic consultation or referral' above.)

Nonoperative treatment and rehabilitation for grade I fractures are described in the text. Throughout rehabilitation, the patient and clinician should remain vigilant for symptoms suggesting recurrence and seek immediate re-evaluation. (See 'Initial treatment' above and 'Follow-up care' above and 'Complications' above.)