Evaluation, diagnosis, and select management of common causes of forefoot pain in adults

INTRODUCTION — Foot pain is common among adults and a frequent reason for primary care visits. Nevertheless, as the differential diagnosis for foot pain is broad and exposure to foot-related problems is often limited during medical training, many primary care clinicians may not be adequately prepared to assess the patient with foot complaints.

This topic reviews the common causes of forefoot pain in the adult, including descriptions of important conditions and a discussion of how to reach a diagnosis. An overview of foot pain generally, including more detailed discussions of foot anatomy and biomechanics and how to conduct a history and examination of the patient with foot complaints, is provided separately. (See "Overview of foot anatomy and biomechanics and assessment of foot pain in adults".)

Topics addressing pain in other regions of the foot and specific injuries and conditions are found separately:

●Pain in the midfoot and hindfoot and foot evaluation (see "Evaluation, diagnosis, and select management of common causes of midfoot pain in adults" and "Evaluation and diagnosis of common causes of hindfoot pain in adults" and "Musculoskeletal ultrasound of the ankle and hindfoot")

●Gait and running injuries (see "Clinical assessment of walking and running gait" and "Running injuries of the lower extremities: Patient evaluation and common conditions", section on 'Foot and ankle injuries')

●Foot fractures (see "Metatarsal shaft fractures" and "Stress fractures of the metatarsal shaft" and "Tarsometatarsal (Lisfranc) joint complex injuries" and "Proximal fifth metatarsal fractures" and "Non-stress fractures of the tarsal (foot) navicular" and "Stress fractures of the tarsal (foot) navicular" and "Cuboid and cuneiform fractures" and "Calcaneus fractures")

●Foot pain related to systemic illness and other conditions (see "Evaluation of the diabetic foot" and "Overview of lower extremity peripheral artery disease" and "Overview of lower extremity peripheral nerve syndromes" and "Clinical manifestations and diagnosis of gout" and "Plantar fasciitis")

ANATOMY AND BIOMECHANICS — The anatomy and biomechanics of the foot are reviewed separately (figure 1). (See "Foot and ankle pain in the active child or skeletally immature adolescent: Evaluation", section on 'Anatomy' and "Overview of foot anatomy and biomechanics and assessment of foot pain in adults", section on 'Basic foot structure and biomechanics'.)

EPIDEMIOLOGY OF LOCALIZED FOREFOOT PAIN — The forefoot is the most common location for foot pain in adults (figure 1). Problems with toes and toenails affect between 60 and 75 percent of older individuals. A survey of 1356 patients with foot and ankle pain revealed that 90 percent experienced pain in more than one location [1]. Common problems include bunions (hallux valgus), hammer toes, and bunionettes; and a majority of adults have corns or calluses located on their toes or plantar foot surface [2]. Forefoot pain causes disabling symptoms in up to 36 percent of individuals older than 70. Females are more commonly affected [1,3].

Certain activities and occupations place significant stress on the feet. In a study of female professional Flamenco dancers, 80.7 percent had metatarsal pain while dancing and 84.1 percent demonstrated plantar hyperkeratosis [4]. Ballet and some forms of martial arts also expose the forefoot to greater risk of injury. Intense training and marching by soldiers and police officers is associated with stress fractures of the forefoot [5]. The surface on which activities are performed may predispose to forefoot pain. As an example, some forms of artificial turf are associated with higher great toe injury rates among both soccer and American football players [6,7].

Multiple medical conditions can affect the forefoot, with osteoarthritis (OA), gout, and rheumatoid arthritis (RA) being among the most common. Obesity, depression, and anxiety are common comorbidities according to survey data [1].

Approximately 90 percent of patients with active RA have forefoot involvement, and foot pain is the leading cause of incapacity in this patient population, with the forefoot being the primary location [8]. RA patients have an odds ratio (OR) of 10.4 for toe pain and 6.3 for forefoot pain compared with unaffected controls [9]. RA patients develop a variety of conditions, including bunions, synovitis, metatarsophalangeal (MTP) joint dislocations, claw toes, and calluses. (See "Clinical manifestations of rheumatoid arthritis".)

Gout has an estimated prevalence of 3 percent, with 80 percent of cases affecting the lower extremity. The first MTP joint is the most common location for a flare. (See "Clinical manifestations and diagnosis of gout".)

OA of the forefoot occurs primarily at the first MTP joint. Few high-quality studies exist, and the literature reports a wide range (6.3 to 39 percent) for first MTP joint arthritis in middle age and older adults [10]. A survey of 5109 adults over age 50 reported that 7.8 percent had first MTP OA, with a higher incidence among females [11]. In this study, 75 percent of those with radiographically documented OA found their pain disabling.

HISTORY AND EXAMINATION — Important elements of the history and examination in patients complaining of foot pain are reviewed separately. Aspects of particular relevance to forefoot pain are discussed below. (See "Overview of foot anatomy and biomechanics and assessment of foot pain in adults", section on 'Anatomy and biomechanics' and "Overview of foot anatomy and biomechanics and assessment of foot pain in adults", section on 'Anatomy-based approach to diagnosis'.)

Several elements of the history may suggest a cause of forefoot pain. As an example, patients with bunions, bunionettes, hallux rigidus (HR), or turf toe often complain of pain while wearing particular shoes that is relieved when alternative shoes are worn. Patients with bunions or bunionettes often feel much less pain when wearing sandals or open-toed shoes, while patients with turf toe or HR experience less pain when wearing a shoe that is stiffer in the forefoot, providing more support.

"It feels like I have a stone in my shoe" or a sensation like stepping on a wadded-up sock, causing pain around the ball of the foot are common complaints from patients with metatarsal pain. Pain when walking barefoot is another common symptom in patients with metatarsalgia. Morton neuroma often causes pain in the same region as metatarsalgia, but the pain is less like stepping on a stone and more of burning or sharp sensation that radiates toward the toes.

The first and most important part of the forefoot examination is visual inspection. Key findings include valgus deviation of the great toe, varus deviation and rotation of the fifth (little) toe, splaying between any of the toes, and hammer toes, interphalangeal joint (IPJ) flexion contractures, or "curly toes." Inspection may also reveal the presence of calluses on the dorsum of proximal interphalangeal (PIP) joints or particularly over the plantar metatarsophalangeal (MTP) joints.

In most cases, the examiner can detect flattening of the transverse, or metatarsal, arch while the patient stands. Weightbearing increases the flattening. Another sign of flattening is that the plantar surface of the arch appears flat or convex across the metatarsal heads rather than concave. Signs of acute injury include redness, swelling, or obvious deformity of a metatarsal or phalanx.

Following inspection, important structures to palpate in the patient with forefoot pain include:

●First MTP joint (great toe)

●Fifth MTP joint

●Plantar surface of MTP joints and just proximal at the diaphyseal shaft

●Fat pad distal to the MTP joint on plantar surface

●Intermetatarsal spaces

●Metatarsal shafts

●Plantar calluses

●Dorsal PIP joint calluses

The examiner should assess the range of motion of the first MTP joint as well as ability to flex and extend the other toes. On the plantar surface, palpable prominence of metatarsal heads may indicate that the plantar plate (figure 2) has been disrupted. Pain or a palpable clicking sensation caused by squeezing the metatarsals together (Mulder sign) suggests neuroma. Burning pain elicited by applying pressure with something like a coin ("quarter test") in the intermetatarsal space is similar to the Tinel sign and also suggests neuroma. Tenderness from pressure or percussion over a particular metatarsal shaft suggests a stress fracture.

DIAGNOSTIC APPROACH TO FOREFOOT PAIN — The authors' approach to forefoot pain begins with the history. The first question is whether the pain is associated with acute trauma. The majority of problems seen in the primary care setting arise from nontraumatic causes that include congenital, structural, and medical conditions. For such atraumatic conditions, evaluation begins with careful inspection of the forefoot. Three general questions guide this inspection as the clinician attempts to narrow the differential diagnosis:

●Are the findings localized to a particular structure or region? This suggests a focal condition or injury (table 1).

●Are there generalized changes to all or multiple metatarsophalangeal (MTP) or proximal interphalangeal (PIP) joints? Generalized change suggests systemic disease, such as osteoarthritis (OA) or rheumatoid arthritis (RA).

●Is there forefoot pain without obvious change in the appearance of the foot? This circumstance is consistent with metatarsalgia or Morton neuroma.

The answers to these questions enable the clinician to determine which category of forefoot problems most likely includes the correct diagnosis. These categories and additional questions to clarify the diagnosis are described in the following table (table 1).

Acute trauma isolated to the forefoot most often involves any of five areas:

●Great toe or the first MTP joint

●Sesamoid bones under the first MTP joint

●Nailbeds

●Lesser toes

●Metatarsals

Five clinical questions guide the examiner to the diagnosis of the most likely injury, as outlined in the following table (table 2). Standard plain radiographs are often obtained as part of the assessment of the acutely traumatized forefoot (image 1) but are often useful in the setting of chronic pain as well, as many associated conditions have degenerative structural manifestations. (See 'Acute injuries' below and 'Chronic forefoot conditions' below and 'Medical conditions causing forefoot pain' below.)

The common conditions causing forefoot pain that are mentioned in the diagnostic tables are described in greater detail below.

COMMON CAUSES OF FOREFOOT PAIN

Chronic forefoot conditions — A number of the more common causes of chronic forefoot pain are described here. A diagnostic approach to the patient with forefoot pain is provided above along with tables summarizing the key clinical questions (table 1 and table 2).

Bunions (hallux valgus) — Valgus malformation of the great toe, commonly known as a bunion, is a common and potentially painful and debilitating condition (figure 3 and figure 4 and image 2). Bunions are the most common problem affecting the forefoot. They can occur in children and young adults but increase in frequency with age. Clinical diagnosis of bunions is primarily based upon a history of great toe pain and increasing valgus deformity. Visual examination of the foot confirms the diagnosis (picture 1 and picture 2).

Patients with bunions have altered foot pressure patterns that are associated with other abnormalities, including a depressed foot arch and greater foot pronation [12]. Many bunions with significant valgus deformity may not cause pain. A study of 197 bunions found that those causing forefoot pain were wider at the transverse arch, consistent with greater ligament breakdown [13]. Radiology studies offer limited value to the primary care clinician but are important for surgeons to determine the best approach to surgical correction. Bunions are discussed in greater detail separately. (See "Hallux valgus deformity (bunion) in adults".)

For athletes who choose to undergo bunion surgery, an average of three months is needed before they can return to play [14]. Of athletes requiring a more extensive procedure because of moderate to severe deformity, overall, approximately 80 percent are able to return to sport.

Hallux rigidus and hallux limitus

Terminology, etiology, and mechanics — Hallux rigidus (HR) describes a first metatarsophalangeal (MTP) joint that shows unusual stiffness, resulting in limited great toe extension (picture 3). The term HR is typically used only when the cause of the reduced range of motion is osteoarthritis (OA) of the first MTP. Hallux limitus (HL) refers to a great toe that lacks normal motion, which may be secondary to soft tissue causes or mild OA that does not demonstrate significant degenerative change at the MTP joint (picture 4).

HL can arise from inflammation, thickening of the joint capsule, or an idiopathic cause possibly representing a complex regional pain syndrome. The most common location of OA of the foot is the first MTP joint. As over 6 percent of middle-aged and older adults have OA, it is likely that a significant percentage of HR stems from joint limitation due to OA [11].

Apart from OA of the first MTP joint, evidence pertaining to other potential causes, anatomic variations, and the biomechanics underlying HR is limited [15]. A family history of HR suggests greater risk, particularly for those with bilateral involvement. Unilateral HR is associated with trauma and female sex. Hallux valgus, metatarsus adductus, and a flattened MTP joint are more common in individuals who develop HR.

For normal walking, approximately 65 degrees of extension of the first MTP joint is ideal. In HR, normal extension is usually reduced by 50 percent or more [16]. One study of great toe extension found that standing active dorsiflexion of the great toe closely approximates the degree of dorsiflexion that occurs during a normal walking gait: Mean MTP dorsiflexion when standing was 44 degrees compared with 42 degrees of extension when walking [17]. While diagnostic criteria vary, most experts consider first MTP extension of less than 30 degrees as abnormal.

Clinical presentation and examination — Patients with HR complain of great toe pain, stiffness, or an uncomfortable bump on the top of their first MTP. While the majority of individuals have significant pain, some patients may have advanced HR without pain, and the problem only becomes apparent when a change in gait is recognized or during evaluation for another condition, such as plantar fasciitis. Redness may be present around the first MTP joint, and examination often reveals squaring or enlargement of the joint. Palpation may reveal bone spurs, local warmth, or focal tenderness. Anteroposterior (AP) and lateral radiographs of the first MTP joint show loss of joint space, bone spurring, and sometimes calcifications. Ultrasound reveals degenerative change at the MTP and can demonstrate joint effusions with hypoechoic change or associated injuries to the extensor tendon.

Management — Primary care clinicians can begin treatment with over-the-counter or custom orthotics and should advise patients to use shoes with adequate room in the toe box. Patients may benefit from wearing shoes with a sole that reduces motion at the first MTP joint. The authors like to add a first ray post to the orthotic to assist with the toe-off phase of walking or running gait. Orthotics are the primary intervention used for most patients treated conservatively. Some patients, particularly those with obvious swelling of the first MTP joint, gain significant pain relief from glucocorticoid injection.

The treatment for HR related to OA and for painful OA follows the same strategy of reducing pressure on the first MTP joint with orthotic inserts and medications to relieve pain. Preliminary study of a novel custom orthotic designed for HR reported significant improvements in function and pain [18].

Since HR causes narrowing of the MTP joint space, the authors prefer using ultrasound to guide any injection. Approach the joint using a dorsal approach just to either side of the extensor tendon. For blind injection, clinicians may find that longitudinal traction opens the joint space slightly and may allow easier entry into the joint space.

Large retrospective reviews suggest that conservative treatment of HL may be effective. In a retrospective series of 772 patients, 428 responded to nonoperative treatments (defined as the ability to return to most activities with acceptable levels of pain) while 296 patients ultimately chose to have surgery [19]. While some studies tracked patients for several years, most long-term studies followed only individuals treated surgically. For this reason, the efficacy of specific nonoperative treatments remains unknown.

Should conservative interventions fail to improve symptoms and function, several surgical treatments are available. These range from relatively basic interventions, such as removal of bone spurs from the joint (eg, cheilectomy), to osteotomies designed to improve joint kinematics (eg, Youngswick procedure), to arthrodesis (ie, joint fusion). Uncontrolled studies suggest that surgery with cheilectomy or arthrodesis provides long-term relief of pain and improved function [20,21]. Hemi- and total joint replacements are another option, but long-term efficacy has not been demonstrated [22].

The primary indications for surgical referral are persistent pain and functional limitations resistant to standard treatments. Since HL involves less structural damage, surgical referral is uncommon. When HR substantially impairs function or prevents the patient from participating in activities they consider important, referral to a foot surgeon is reasonable. Patients with significant dorsal osteophytes on radiograph accompanied by significant movement restrictions of the great toe may benefit from earlier surgical referral for possible cheilectomy.

Athletes and active individuals who undergo first MTP arthrodesis can return to most sports and exercise activities. In a retrospective study of 50 patients who underwent the procedure, 27.4 percent rated activities as less difficult postoperatively, 51.2 percent as the same, and 21.4 percent as more difficult [23]. Patients had resumed approximately half of their preoperative activities by six months and nearly 90 percent at long-term follow-up. Satisfaction with the procedure was 96 percent. For young athletes participating in running, jumping, and ballet, eight weeks was needed before return to sport, but soccer players required 16 weeks or longer [24].

Metatarsalgia

Etiology and epidemiology — Metatarsalgia is the term commonly used to describe pain at the plantar surface of the distal diaphysis of the second and third metatarsals. Typically, pain arises from partial or complete collapse of the transverse arch formed by the metatarsal heads (figure 5). Metatarsalgia can develop from poor gait biomechanics, abnormal foot anatomy, or congenital abnormalities affecting the foot or ankle [25]. While changes like bunions (picture 1) and bunionettes (picture 5) in the first and fifth rays are often associated with metatarsalgia, the condition also occurs in otherwise normal feet.

The key structural abnormality that develops in metatarsalgia is loss of the support provided by the transmetatarsal ligaments and capsule, which suspend the distal shaft of the metatarsals at the diaphysis. If too much pressure is placed on these ligaments, they can break down over time and allow the first ray to deviate (ie, splay) (picture 6 and picture 7). If the capsule breaks down on the plantar surface, a metatarsal head may sublux toward the plantar surface or a proximal phalanx may displace dorsally. In extreme cases, this produces a hammer toe (picture 8) from entrapment of the metatarsal head and flexor tendon.

Older patients are at greater risk of developing metatarsalgia [26], and females are affected more often than males. Athletes in sports like distance running whose forefeet repetitively sustain large impact forces are at increased risk. Pressure on the forefoot may be increased in athletes who frequently wear shoes that have spikes (eg, baseball or track cleats), provide only limited support (so-called "minimalist shoes"), or have an excessive heel-to-forefoot drop.

The most common anatomic abnormality associated with metatarsalgia is a short first metatarsal or a long second metatarsal. However, extreme pes planus or pes cavus changes of the arch are often associated with metatarsal pain even when metatarsal length remains normal. Individuals with failed bunion or HR surgery may displace pressure from the first MTP plantar surface to the central metatarsals, thereby developing an acquired form of metatarsalgia [27].

Clinical presentation, evaluation, and differential diagnosis — Patients with metatarsalgia complain of sharp pain on the plantar surface of the foot in the area of the distal metatarsals. The pain is often described as feeling like they are stepping on a stone. The second and third metatarsal heads are the most common location of the pain. The pain is relieved by sitting or sometimes when wearing shoes that offer forefoot support. Barefoot walking increases the discomfort. Dorsal pain occurs more often with a stress fracture and is not typical of metatarsalgia. Burning or neuropathic pain points toward neuroma or neuritis. Along with stress fracture and Morton neuroma, the differential diagnosis in adolescents includes Freiberg disease (avascular necrosis of metatarsal head). (See "Overview of the causes of limp in children".)

Clinical findings of metatarsalgia include flattening of the transverse arch or splaying of the toes that is seen when the patient stands and loss of the metatarsal arch on the plantar surface that is seen when the patient sits (picture 9). Abnormal plantar calluses can develop over any of the metatarsal heads, most often over the second, often referred to as Morton callus. Palpation elicits pain at the distal plantar diaphysis just proximal to the metatarsal head. Neither standard radiographs nor ultrasound helps to confirm the diagnosis of metatarsalgia. Imaging is reserved for cases where a metatarsal stress fracture is suspected or standard therapy is ineffective, raising the possibility of rare causes of foot pain such as a metastatic tumor or bone cyst.

Plantar adventitious bursitis is a relatively common condition that mimics metatarsalgia [28,29]. The pain in this condition localizes just distal to the metatarsal head in the fat pad. Palpation may identify a soft tissue mass that may be a true bursa or inflamed soft tissue. Ultrasound and magnetic resonance imaging (MRI) reveal a mixed solid and cystic mass. The importance in making this distinction is that metatarsal padding may not alleviate or could possibly worsen pressure and pain. In such cases, corrective orthotics and forefoot support should be used for treatment. In general, biopsy of these masses can be deferred assuming no other worrisome clinical signs or symptoms are present.

Management — The initial treatment for metatarsalgia consists of metatarsal pads (picture 10 and table 3). A small observational study comparing walking shoes, sandals, and a customized sandal with a built-in metatarsal pad reported that walking time without pain doubled and distance increased two to three times in the customized sandal compared with the other shoe wear [30]. Small uncontrolled prospective studies suggest that correct placement of these pads (such that distal plantar pressure is reduced) correlates strongly with pain relief [31]. Metatarsal pads are particularly important for older patients, in whom forefoot pain is associated with decreased physical activity and increased risk of falling.

If metatarsal pads are ineffective, small observational studies suggest that customized orthotics designed to unload the distal metatarsals and distribute plantar pressure more evenly substantially reduce pain and allow patients to increase their walking [32]. In addition, preliminary research suggests that toe and foot exercises can help alleviate pain and improve function [33]. This suggests that strengthening the muscular support to the arch plays a role in recovery.

Surgical referral is a last resort for metatarsalgia but merited in specific cases. The key indication is pain in the forefoot that persists despite multiple attempts to relieve this with mechanical correction. When metatarsalgia pain limits the ability of the patient to walk or remain active, surgical referral is appropriate so the full range of possible interventions may be discussed. The ideal time frame for surgery is unknown.

The traditional surgical procedure (metatarsal osteotomy) tends to fail over time [25]. However, newer reconstruction techniques offer promise for patients with unrelenting pain. A study of 50 reconstructions of lesser MTP joints reported that 92 percent of patients had improved stability and function with less pain [34]. Newer techniques including minimally invasive, percutaneous surgery. Small studies comparing mini-invasive techniques with conventional ones (Weil osteotomy) report comparable outcomes for pain and general function with improved mobility [35,36]. Management of patients with metatarsalgia from rheumatoid arthritis (RA) is discussed separately. (See "Initial treatment of rheumatoid arthritis in adults" and "Nonpharmacologic therapies for patients with rheumatoid arthritis".)

Interdigital (Morton) neuroma

Etiology and epidemiology — Interdigital neuromas of the foot are often referred to as Morton neuroma, though other names have been suggested based on possible causes [37]. The etiology of Morton neuroma is not fully understood but is thought to be similar to metatarsalgia, involving collapse of the transverse arch that places traction and increased pressure on the interdigital nerve, ultimately leading to injury [37]. Overpronation and tight shoes are often associated with the condition. Morton neuroma is a common problem in athletic and nonathletic populations. Females are approximately five times more likely than males to develop Morton neuroma [38].

Clinical presentation and examination — The patient with a neuroma most commonly complains of a burning pain in the third intermetatarsal space (between the third and fourth distal metatarsals) that may radiate towards the toes (figure 6) [39]. However, the condition may also develop in the first, second, or fourth interspaces. An intermetatarsal bursitis can cause a similar pain. Some patients may complain of numbness of the involved toes or pain that increases with activity. Examination may reveal a clicking sensation (Mulder sign) when palpating the involved interspace while simultaneously squeezing the metatarsal joints. Direct palpation may reveal tenderness. Some clinicians apply pressure to a quarter or similar-sized coin while rolling it between the metatarsals to see if this elicits focal pain.

Diagnostic imaging — Ultrasound offers an inexpensive option for identifying Morton neuroma with accuracy comparable to MRI and can help to distinguish a neuroma from intermetatarsal bursal swelling or synovitis in adjacent joints (image 3) [40-43]. Characteristic lesions over 5 mm in diameter are considered clinically important. The use of MRI to diagnose Morton neuroma (image 4) is problematic because features consistent with neuroma may appear in as many as one-third of asymptomatic individuals [44,45].

Conservative management — Conservative treatment should precede expensive diagnostic procedures. This approach involves decreasing pressure on the metatarsal heads by using a metatarsal support or bar or padded shoe insert. Several studies have measured the loading pressures placed on metatarsals before and after the use of metatarsal pads, bars, orthotics, and specialized orthopedic shoes [31,46-50]. In all reports, pain relief correlated with reduction in pressure. Proper placement of the inserts just proximal to the metatarsal head is important. A well-blinded, randomized trial comparing customized orthotics with a long arch and metatarsal support versus a flat insole of the same material demonstrated significant improvements in walking pain, foot function, and physical activity in the custom orthotics group [51].

Treatment inserts are often placed in both shoes, even when symptoms are unilateral, to ensure that the patient walks evenly, but bilateral pads are not always needed. Symptomatic relief often begins within a few days of insert use, and pain may completely subside over several weeks.

A broad-toed shoe that allows spreading of the metatarsal heads may be helpful. Proper shoe width should be determined while standing, using a professional shoe-fitting device. If width has changed, older shoes should be discarded.

Strength exercises for the intrinsic foot muscles are often part of conservative treatment. No randomized controlled studies have been performed to assess these interventions.

Additional interventions if conservative management ineffective — If conservative measures fail to relieve symptoms, a single injection of a glucocorticoid and local anesthetic into the site of tenderness can be performed using a dorsal, not plantar, approach [52-54]. A plantar approach is more likely to cause complications.

A number of combinations have been used. We prefer to inject triamcinolone 0.5 mL (10 mg/mL solution) and lidocaine 0.5 mL (1% solution). In addition, we limit the total volume of the injection to 1 mL to minimize discomfort and reduce the risk of fat pad atrophy, although up to 2 mL total volume may be used. Some study authors have used a combination of methylprednisolone (20 mg, or 0.5 mL) and 1% lidocaine [52].

Ultrasound-guided injection is preferred by many practitioners to ensure accurate needle placement. While limited, evidence suggests that ultrasound-guided injection provides more effective short- and long-term analgesia, although injection guided by anatomic landmarks can also be effective [55,56].

Most patients experience some benefit from glucocorticoid injection. Relief can last three months or longer with ultrasound-guided injection according to small randomized trials and multiple case series [52,56-59]. In addition, the use of a glucocorticoid appears to give somewhat better relief than injection of a local anesthetic alone [52]. Complications are rare; metatarsal fat pad atrophy can be debilitating but may occur less often if a dorsal injection is used and injection is guided by ultrasound.

A range of nonsurgical therapies have been studied. Meta-analyses of studies including nine interventions reported that glucocorticoid injection had the strongest evidence for benefit [53,60]. Manipulation and mobilization showed benefit in one meta-analysis; alcohol injection showed short-term benefit in another.

Studies of extracorporeal shockwave therapy, injections of sclerosing substances or Botox, radiofrequency ablation, capsaicin, and cryoneurolysis consist primarily of case series [53,60]. Other treatments, including injection of alcohol and radiofrequency therapy to ablate the neuroma, show promise in observational case series [61-63]. These interventions should be considered experimental until further study clarifies their efficacy.

Precise location of injection therapies appears to improve success rates. In an observational study, ethanol injections performed under fluoroscopic and electroneurographic guidance improved pain and function in 82 percent of patients at five-year follow-up [64]. A study of ultrasound-guided hyaluronic acid injections weekly for three weeks reported excellent pain relief persisting for 12 months [65].

Surgical referral — Surgical removal of the neuroma and nerve may be necessary in patients who remain symptomatic after 9 to 12 months of nonoperative therapy. Surgical success rates of up to 80 to 90 percent have been reported in some uncontrolled studies [66-69]. However, others report much lower success rates and emphasize potential complications [70,71]. If surgery is performed, a dorsal approach appears to allow earlier weightbearing and return to work and causes less painful scarring [72]. No randomized trials of surgery for plantar neuroma have been reported. Rarely, a neuroma may recur following surgery.

Bunionette (tailor's bunion) — Bunionettes are painful bony prominences that occur over the lateral aspect of the fifth (little toe) MTP joint (picture 5). In most cases, there is a prominence of the metatarsal head and a varus angle or subluxation of the fifth MTP joint. A widened fourth to fifth intermetatarsal angle suggests either genetic or structural alteration. Injury to the fourth to fifth intermetatarsal ligament from altered gait involving either excessive compensatory supination during toe-off or a supinated foot strike may cause increased separation between the fourth and fifth rays and result in breakdown of the MTP joint capsule (picture 11) [73].

Most bunionettes are readily detected by visual inspection of the foot and rarely cause significant symptoms. When symptoms do occur, they typically include pain directly over the fifth MTP joint or over the lateral aspect of the fifth MTP with pressure from the shoe. Examination may reveal abnormal callusing (picture 12) and sometimes mild MTP joint swelling. Radiographs have no routine role except in patients considering surgery.

For those who have mild to moderate symptoms, shoes with a wider toe box or an orthotic that incorporates a lateral fifth ray post often relieves the pain (picture 13 and picture 14). Patients with an extremely supinated gait or foot strike may require a more extensive orthotic correction. Most symptomatic patients respond adequately to conservative care [74]. Surgery may be necessary in athletes who cannot compete or patients whose ability to walk is compromised due to severe pain [75]. Distal osteotomies and other procedures can help to relieve pain and restore foot function, and recurrence rates appear to be low, although controlled studies are lacking.

Hammer toes, claw toes, and lesser toe deformities — These deformities are relatively common and arise from soft tissue injury, inflammatory arthritis, neuromuscular disorders, or trauma, although genetic predisposition may play a role (picture 15) [76]. In the Framingham foot study involving 2446 patients with an average age of 66 years, lesser toe deformities occurred in 29.6 percent [26].

The mechanism underlying hammer toe deformities is complex. Collapse of the transverse arch (figure 5) is associated with breakdown of the transmetatarsal ligaments [77]. In milder cases, the plantar plate (figure 2) becomes depressed or flattened. In more severe cases, the plantar plate may be displaced toward the dorsal aspect of the metatarsal head or may rupture. In either case, the metatarsal head is displaced toward the plantar surface. Usually, the base of the proximal phalanx displaces dorsally at the MTP joint.

If the metatarsal heads "drop" or become entrapped in a defect in the plantar plate, the toe becomes trapped in flexion. This causes some hyperextension of the first phalanx on the MTP joint and may cause flexion at the proximal interphalangeal (PIP) joint depending on the pattern of tissue injury. The distal interphalangeal (DIP) joint usually remains neutral. Pain may be felt at the plantar surface over the MTP joint. Often, when the flexion contracture is significant, the dorsum of the PIP joint is pushed against the shoe and calluses form over the joint. These are commonly referred to as traumatic "knuckle pads" and may become painful or cause skin ulceration. Both MRI and ultrasound have high sensitivity for plantar plate tears, but MRI shows greater accuracy [78].

Other less common toe deformities include "curly toes," mallet toes, crossover toes, and claw toes. These arise from a variety of soft tissue trauma, often related to underlying medical or neurologic conditions. Most of these deformities are treated only when they create significant symptoms. When hammer toes or lesser toe deformities cause significant pain or interfere with gait, surgical correction is required (picture 15). The results of observational studies suggest that operative correction of hammer toes provides significant relief to a large percentage of patients in all age groups, with complications rates of approximately 10 percent [79,80]. For less severe symptomatic cases, hammer toe pads, buddy taping, shoes with a roomy toe box, and various orthotic straps and forefoot padding may offer some pain relief [76]. For more severe forefoot deformity, including combinations of hallux valgus, hammer toes, claw toes, and other lesser toe deformities, complex forefoot reconstructions can restore more normal alignment and partially repair the plantar plate. This allows better function for many patients.

Claw toes are a possible indication of neurologic injury. In a claw toe, there is dorsiflexion of the proximal phalanx on the MTP joint and plantarflexion of the PIP and DIP joints (picture 15). This differs from curly toes that have flexion of the MTP, PIP, and DIP joints. Mallet toes show a flexion contracture of the DIP joint only. Claw toes are relatively common in patients after the seventh decade of life, with females developing them more frequently. While older patients do not have a secondary cause in most cases, younger patients often do, and it is important to consider such causes as lumbar radiculopathy, diabetic neuropathy, inflammatory arthropathy, or a neuromuscular condition in these patients.

Hammer toes and claw toes have particular importance in diabetic patients, among whom prevalence ranges from 32 to 46 percent [81]. These deformities are associated with greater plantar forefoot pressure. Prospective studies suggest that hammer toes and claw toes increase the risk for developing foot ulcers in diabetic patients. However, the mechanism for these injuries is complex, and intrinsic muscle imbalance and weakness alone do not predict which diabetics develop hammer or claw toes. (See "Evaluation of the diabetic foot".)

Mini-invasive techniques enable surgical repair of some structural abnormalities of lesser toes [82]. Indications for surgical referral may include persistent pain, compromised ability to stand or walk, and inability to find accommodating shoes. A small prospective surgical trial compared mini-osteotomies (73 osteotomies) with Weil osteotomy (45 osteotomies) and found equivalent outcomes after follow-up of 13 months.

Brachymetatarsia — Brachymetatarsia refers to abnormally shortened metatarsals. Among active adults, first and fourth brachymetatarsia are most common (picture 16 and picture 17 and picture 18). Females are predominately affected [83]. Some variants are due to rare genetic conditions or intrauterine trauma. First metatarsal insufficiency is a common term that suggests the degree of shortening of the first metatarsal alters the normal function of the first ray. A short first metatarsal, with or without associated hypermobility, destabilizes the foot's axis of balance and allows excessive pronation. This places additional stress on the central metatarsals. Morton foot (named for the anatomist Dudley Morton) consists of a triad of findings, including a congenitally short first metatarsal, a hypermobile first metatarsal segment (picture 9 and picture 2 and picture 19), and calluses under the second and third metatarsals (picture 20) [84,85].

The authors suggest that first brachymetatarsia is likely to be clinically significant when the condition appears extreme on visual inspection or when the patient's gait shows excessive forefoot pronation or lack of push-off from the great toe. Palpation of the first and second metatarsal can give the clinician a sense of whether the first metatarsal is much shorter than the second; standard foot radiographs are used to confirm the discrepancy. The abnormal motion created by first brachymetatarsia may destabilize the first MTP joint, leading to HR, bunion formation, and chronic forefoot pain. In addition, the additional load placed on the lateral metatarsals often leads to a more generalized breakdown of the entire forefoot, causing callus formation and pain from metatarsal injury. Pain is often reduced and function improved with a custom orthotic.

Fourth brachymetatarsia is easily recognizable by appearance. The shortened fourth metatarsal allows the fourth phalanx to displace dorsally so that it often overlaps the dorsum of the fifth phalanx. This condition leads to an excessively thin forefoot and less stability with pronation and supination during normal gait. Orthotics can help to provide stability. If the dorsally displaced fourth phalanx is painful or does not fit into shoes, some patients opt for amputation of the phalanx. Lengthening procedures have been performed for all types of brachymetatarsia, particularly in younger patients. While such procedures may improve appearance, many patients have complications including MTP stiffness and rotation of the affected ray [86].

Surgical intervention for brachymetatarsia is rarely indicated. While surgical options have improved, complication rates are high, and many surgeons will only operate if the patient experiences significant pain or instability with stance or gait; they do not operate for cosmetic concerns alone. For hypoplastic metatarsals, lengthening procedures, sometimes involving shortening of the adjacent metatarsal, may be required [83].

Patients may have an isolated long second ray without shortening of the first metatarsal, but this condition tends to place less stress and cause less severe problems in the forefoot (picture 21). In this condition, symptoms most often develop at the proximal or distal interphalangeal joint of the long second toe from pressure at the end of the shoe.

Poorly defined generalized forefoot pain — Some patients develop significant forefoot pain without a clear single cause. Surveys show that 90 percent of patients complain of foot pain in more than one location [1]. While such patients may have early findings of a bunion or bunionette, flattening of the metatarsal arch, or similar changes, the pain pattern cannot be attributed to a specific diagnosis. In most such cases, a trial of custom orthotics appears preferable to other treatments.

This approach is supported by the results of a systematic review of nine studies with 487 patients suffering from a variety of conditions causing forefoot pain that found custom orthotics to be the most effective intervention for reducing pain [87]. A study using ultrasound to monitor the effectiveness of custom orthotics on plantar forefoot pain reported a significant reduction in symptoms and disability, and subsequently, a significant decrease in intermetatarsal bursitis [88].

Cutaneous conditions — Calluses, corns, and plantar warts are common causes of forefoot discomfort. Diabetic foot ulcers and other less common skin lesions that may appear on the foot are reviewed separately. (See "Evaluation of the diabetic foot" and "Overview of benign lesions of the skin".)

Corns and calluses — The most common callus of the foot occurs proximal to the second MTP joint on the plantar surface and is sometimes called "Morton callus." Morton callus arises from a drop of the second metatarsal head (picture 22), which is the most common location for loss of ligamentous support in the transverse arch. As the metatarsal head subluxes and breaks through the metatarsal plate, pressure from the bone on the plantar surface creates friction and ultimately callus. In patients with neuropathy involving the feet, this callus often breaks down to form an ulcer.

Corns differ from calluses in having a hyperkeratotic core (picture 23). Both calluses and corns appear to arise from abnormal pressure over the skin and bony prominences from shoes or foot breakdown. For older patients with calluses, partial debridement provides similar relief to full debridement and is a safer office procedure [89]. The diagnostic approach and treatment for each are described separately. (See "Overview of benign lesions of the skin", section on 'Calluses and corns'.)

Plantar wart — Cutaneous warts that develop on the plantar surface of the foot are termed plantar warts. They are a cutaneous manifestation of human papillomavirus type 1 (HPV 1). The appearance of plantar warts mimics that of calluses and corns (picture 24), but scraping the hyperkeratotic surface with a sharp blade reveals thrombosed capillaries (picture 25) not present in the other conditions. The diagnosis and management of warts are discussed separately. (See "Cutaneous warts (common, plantar, and flat warts)".)

Acute injuries

Toe fracture — Toe fractures are part of the differential diagnosis whenever the forefoot sustains trauma. Other injuries that may be sustained from such trauma include toe dislocations, turf toe, and subungual hematoma. Great toe fractures and open or intra-articular fractures involving other toes all can cause long-term problems with foot function and gait and therefore require careful management. A history of trauma accompanied by a swollen, tender toe, with or without rotation or malalignment, warrants radiographic assessment. Plain radiographs generally confirm the diagnosis. (See "Toe fractures in adults".)

Blows directed at the plantar surface of one or more toes that cause a fracture may also result in bleeding at the nailbed (ie, subungual hematoma). (See 'Subungual hematoma' below.)

Metatarsal fracture and stress fracture — Focal tenderness and swelling over the dorsum of a metatarsal shaft immediately following trauma to the area suggests an acute metatarsal fracture, while a history of overuse in a patient with similar signs suggests a metatarsal stress fracture. Most such fractures involve the middle metatarsals (ie, second, third, and fourth). Fractures of the first (great toe) or fifth (little toe) metatarsal warrant careful assessment and close follow-up, as both play key roles in walking and running gait. Early stress fractures may not be apparent on plain radiographs.

Detailed discussions of the diagnosis and management of acute metatarsal fractures and metatarsal stress fractures are found separately. (See "Stress fractures of the metatarsal shaft" and "Metatarsal shaft fractures".)

First metatarsophalangeal joint sprain ("turf toe") — So-called "turf toe" is a sprain of the first MTP joint caused by forced hyperextension of the great toe as it strikes the ground or another player [90]. Depending upon the severity of injury, there is some degree of swelling, discoloration, and tenderness around the first MTP joint. Passive flexion and extension of the great toe is painful. A dorsal-plantar drawer test performed at the MTP joint can be used to assess the stability of the plantar ligament complex. The test involves grasping the distal first metatarsal with one hand and the proximal first phalanx with the other and gently attempting to displace the phalanx dorsally. Displacement or pain marks a positive test.

●Grade 1 injuries represent a sprain of the plantar capsular ligament complex that is painful but not disabling. With taping and rigid first ray support in the shoe, many athletes continue to compete [90].

●Grade 2 injuries represent a partial rupture of the plantar capsular ligament complex that requires most athletes to rest for approximately two weeks before returning to sports. Management includes protection similar to that for a grade 1 injury.

●Grade 3 injuries are significant tears of the plantar MTP structures such that recovery is prolonged, often requiring three to four months. More severe injuries (approximately 2 percent) may require surgical repair.

Grade 3 injuries are generally associated with severe swelling and ecchymosis, weakness of great toe flexion, and instability of the first MTP joint. Such injuries should be referred to a foot and ankle surgeon.

Acute treatment for all injuries involves icing, protection (support that prevents first MTP extension), and elevation. Crutches may be needed for more severe injuries to rest the foot and facilitate healing. Athletes recovering from turf toe may benefit from additional support as they return to play, such as the taping shown in the following graphic (picture 26).

In certain sports, the plantar plate of the first MTP joint (figure 2) is at higher risk of injury. American football running backs and quarterbacks appear to be at increased risk. Other risk factors for turf toe include playing on artificial surfaces. Intensity of play appears to be another factor, as the risk of injury is 14 times higher in games versus practice [6]. The overall incidence is rare (0.062 injuries per 1000 athlete exposures) and equally related to contact with the playing surface (35.4 percent) and with another player (32.7 percent).

Sesamoid injury — Sesamoid bones of the foot appear in variable locations and with different frequencies depending on ancestry. They are almost uniformly present at the plantar surface of the first MTP joint (image 5) but develop less often at other MTP and PIP joints [91]. About 10 percent of patients have one or more partitions in one or more of the sesamoids, and these are sometimes mistaken for fractures (image 6).

Patients with a sesamoid injury often complain of pain below the first MTP joint. While some recall acute trauma that produced the pain, most describe the pain as developing insidiously after repetitive training, typically involving running or jumping. They may note that a particular shoe with a hard cleat post or pronounced wear in the forefoot appears to trigger their pain. Often, barefoot walking puts pressure on the plantar MTP surface and causes symptoms. A retrospective review of 58 young athletes with sesamoid fractures found that the majority occurred in females (n = 51), and the sports most often associated were dance (37.9 percent), running (13.8 percent), and gymnastics (13.8 percent) [92]. Most injuries appeared to be stress fractures rather than from acute trauma.

On examination, direct pressure at the plantar surface over one of the sesamoids, usually below the first MTP joint, elicits pain. Rarely is there any notable swelling or discoloration. A prominent callus below the first MTP suggests chronic pressure at this area. Active or passive flexion and extension of the great toe, or resistance to these motions from the examiner, usually does not elicit pain. However, extension of the great toe while the examiner applies pressure to the sesamoid does elicit pain.

The differential diagnosis for sesamoid-related pain includes:

●Traumatic or stress fracture of sesamoid or adjacent bone

●Sesamoiditis

●Bursitis

●Osteochondritis

●Flexor hallucis brevis tendinopathy

●Medial plantar digital nerve entrapment

●Chondromalacia

●Sesamoid-MTP arthritis

●Sesamoid osteonecrosis (rare) [93]

Evaluation and treatment of sesamoid fracture is discussed separately. (See "Sesamoid fractures of the foot".)

Toe dislocation — Toe dislocations are not common. Most occur when significant forces cause lateral or dorsal displacement of the toe. With the exception of injuries involving the fifth (little) toe MTP joint, many toe dislocations are complex injuries (some involving fractures), and often, management by a specialist is indicated. Reduction of simple dislocations is discussed separately. (See "Digit dislocation reduction".)

Os intermetatarseum and polymetatarsia — Os intermetatarseum is a rare cause of pain between the base of the first and second metatarsals. Patients note a bump in this region caused by an accessory ossicle, which is usually asymptomatic [94]. An even rarer cause of metatarsal area pain is polymetatarsia, which is caused when a fourth or fifth metatarsal is duplicated either in the presence or absence of polydactyly [95].

Medical conditions causing forefoot pain

Gout — Gout is a disease of urate crystal deposition that can cause intense, recurrent attacks of inflammatory arthritis of the first MTP joint. The first MTP joint continues to be the most common location of gout attacks, and a meta-analysis found that 73 percent of over 2000 gout patients had developed first MTP arthritis [96]. However, gout can affect sesamoids, interphalangeal joints (IPJs), and other areas of the forefoot [97,98]. With the exception of major trauma, few conditions produce MTP joint pain as intense as that described by gout patients. Gout often has specific findings on plain radiograph and ultrasound (image 7 and image 8). Aspiration of joint fluid for urate crystals confirms the diagnosis. (See "Clinical manifestations and diagnosis of gout" and "Treatment of gout flares".)

Rheumatoid arthritis — Foot involvement in RA mimics findings in the hands. MTP joint pain occurs early, and pain and puffiness often precede structural changes. Ultimately erosive changes occur in multiple MTP joints, and as destruction progresses, the toes often deviate laterally.

RA also causes extensive callusing of the forefoot (picture 27) when inflammatory processes erode the metatarsal planter plate and metatarsal heads sublux to the plantar surface of the foot (picture 28). This subluxation may lead to hammer toes (picture 15) or various degrees of rotation and hyperextension of the toes. The clinical manifestations of RA are discussed in greater detail separately. (See "Clinical manifestations of rheumatoid arthritis".)

Complex regional pain syndrome — According to a retrospective review of 390 elective foot surgeries, complex regional pain syndrome developed in 4.7 percent of cases, with the majority involving the forefoot [99]. In addition, trauma and idiopathic causes can produce complex regional pain syndrome of the forefoot. (See "Complex regional pain syndrome in adults: Pathogenesis, clinical manifestations, and diagnosis".)

Diabetes — Chronic diabetic neuropathy can ultimately lead to the development of foot ulcers. Issues related to the diabetic foot are reviewed in detail separately. (See "Screening for diabetic polyneuropathy" and "Evaluation of the diabetic foot".)

Conditions affecting the toenails

Ingrown toenail — An ingrown toenail develops when a spicule of the lateral nail plate pierces the lateral nail fold and skin, causing an inflammatory reaction. Many become infected. The condition is obvious on inspection (picture 29). Treatment is discussed separately. (See "Ingrown nails".)

Subungual hematoma — Traumatic injury of the toe, typically a direct blow to the distal phalanx, to can cause bleeding of the nailbed resulting in a hematoma to beneath the nail (picture 30). These can cause significant pain that requires drainage (trephination) for relief. The diagnosis and management of subungual hematoma, including how to perform trephination, are discussed separately. (See "Subungual hematoma".)

Nail dystrophy — Multiple conditions can cause toenails to become malformed or discolored. Such changes may stem from systemic disease, skin disease, localized infection, or chronic trauma. The assessment and differential diagnosis for these conditions are reviewed separately. (See "Overview of nail disorders".)

SUMMARY AND RECOMMENDATIONS

●Assessment of foot pain – Important elements of the history and examination in patients complaining of foot pain generally are reviewed separately. Aspects of particular relevance to forefoot pain are discussed above. (See "Overview of foot anatomy and biomechanics and assessment of foot pain in adults", section on 'Anatomy and biomechanics' and "Overview of foot anatomy and biomechanics and assessment of foot pain in adults", section on 'Anatomy-based approach to diagnosis' and 'History and examination' above.)

●Epidemiology – The forefoot is the most common location for foot pain in adults (figure 1). Problems with toes and toenails affect the majority of older individuals. Common problems include bunions (hallux valgus), metatarsalgia, hammer toes, and bunionettes; and a majority of adults have corns or calluses located on their toes or plantar foot surface. (See 'Epidemiology of localized forefoot pain' above and 'Common causes of forefoot pain' above.)

●Inspection – The first and most important part of the forefoot examination is visual inspection. Key findings include valgus deviation of the great toe (picture 1), varus deviation and rotation of the fifth (little) toe (picture 5), splaying between any of the toes (picture 2), hammer toes (picture 15), and interphalangeal joint (IPJ) flexion contractures or "curly toes." Inspection may also reveal the presence of calluses on the dorsum of proximal interphalangeal (PIP) joints or particularly over the plantar metatarsophalangeal (MTP) joints. (See 'History and examination' above.)

●Palpation – Following inspection, important structures to palpate in the patient with forefoot pain include (figure 7 and figure 8 and figure 9):

•First MTP joint (great toe)

•Fifth MTP joint

•Plantar surface of MTP joints and just proximal at the diaphyseal shaft

•Fat pad distal to the MTP joint on plantar surface

•Intermetatarsal spaces

•Metatarsal shafts

•Plantar calluses

•Dorsal proximal IPJ calluses

The examiner should assess the range of motion of the first MTP joint (picture 3) as well as ability to flex and extend the other toes.

●Diagnosis of nontraumatic causes – The majority of problems seen in the primary care setting arise from nontraumatic causes that include congenital, structural, and medical conditions. The following table summarizes our diagnostic approach to such conditions (table 1). (See 'Diagnostic approach to forefoot pain' above.)

●Diagnosis of traumatic causes – Trauma isolated to the forefoot most often involves any of five areas:

•Great toe or the first MTP joint

•Sesamoid bones under the first MTP joint

•Nailbeds

•Lesser toes

•Metatarsals

Five clinical questions guide the examiner to the diagnosis of the most likely injury, as outlined in the following table (table 2). (See 'Diagnostic approach to forefoot pain' above.)

●Management of nontraumatic causes – Nontraumatic forefoot pain can often be treated successfully with appropriate footwear modifications (eg, pads, insoles, orthotics), activity modification, and (in some cases) injection of glucocorticoid or analgesic. When conservative management is ineffective, surgical referral is appropriate. Management of select causes of forefoot pain is reviewed above (see 'Chronic forefoot conditions' above); evaluation and management of medical conditions causing forefoot pain are discussed separately. (See "Clinical manifestations and diagnosis of gout" and "Treatment of gout flares" and "Evaluation of the diabetic foot" and "Management of diabetic foot ulcers" and "Clinical manifestations of rheumatoid arthritis".)

●Management of traumatic causes – Management of toe and forefoot fractures varies depending on the location and complexity of the injury. Acute first MTP joint sprain ("turf toe") can usually be treated conservatively with relative rest and supportive taping. Management of most traumatic causes is reviewed separately. (see "Stress fractures of the metatarsal shaft" and "Metatarsal shaft fractures" and "Toe fractures in adults" and "Metatarsal and toe fractures in children" and "Sesamoid fractures of the foot").