Metatarsalgia

The foot is frequently injured during sports activities that typically involve repetitive high-pressure loading on the forefoot.[2, 3]

As in many other overuse syndromes, the condition may be the result of an alteration in normal biomechanics that has caused an abnormal weight distribution among the metatarsal heads.

Persistent stress can lead to chronic irritation and inflammation of the periosteum and adjacent tissues.

The following factors can contribute to excessive localized pressure over the forefoot:

• High level of activity

• Prominent metatarsal heads

• Tight toe extensors

• Weak toe flexors

• Hammertoe deformity (See also the Medscape Reference article Hammertoe Deformity.)

• Hypermobile first ray

• Tight Achilles tendon

• Excessive pronation

• Equinus deformity (See also the Medscape Reference articles Clubfoot and Clubfoot Imaging.)

Some anatomic conditions may predispose individuals to forefoot problems, such as the following.

• A high arch with stress to the forefoot, as seen with pes cavus foot type, often causes pain in the metatarsal region. (See also the Medscape Reference article Pes Cavus.)

• Individuals with a Morton toe have a short first metatarsal bone. The normal forefoot balance is disturbed, which results in abnormal subtalar joint pronation. This pronation results in the shift of an increased amount of weight to the second metatarsal.

• Iatrogenic changes from surgeries such as osteotomies can change the anatomy of the foot, resulting in unequal force distribution and metatarsalgia.[4]

Hammertoe deformity causes metatarsalgia because the top of the shoe pushes the toe down, depressing the metatarsal head. The toes also share some weight bearing. Hallux valgus may create abnormal foot biomechanics. (See also the Medscape Reference article Hallux Valgus.) These musculoskeletal problems may contribute to forefoot trauma in athletes. Calluses are formed as a skin reaction to prolonged pressure, with the skin becoming thickened and hyperkeratotic.

United States statistics

Athletes who participate in high-impact sports that involve the lower extremities commonly present with forefoot injuries, including metatarsalgia.[2, 3]

Athletes, especially those who are middle-aged women, may experience a gradual onset of pain that is associated with improper footwear, a change in running terrain, or a rapid increase in training intensity.[5]

Body weight is transferred to the foot by gravity. This transfer of force is increased to the forefoot during the mid-stance and push-off phases of walking and running.[3, 6] In the forefoot region, the first and second metatarsal heads receive the greatest amount of this energy transfer. Peak vertical forces reach 275% of body weight during running, and a runner may absorb 110 tons per foot while running 1 mile.[3] Pressure studies have shown that runners spend most of the time weighted over the forefoot while running.

Athletes who take part in high-impact sports that involve running or jumping are at high risk of forefoot injuries.[2, 3] Although track-and-field runners are exposed to the highest level of traumatic forces to the forefoot, many other athletes, including tennis, football, baseball, and soccer players, often present with forefoot injuries.

Generally, with the treatment described in the Treatment section, the prognosis for metatarsalgia is good.

Complications

Freiberg avascular necrosis can occur from a congenital, traumatic, or vascular etiology. An athletic injury is unlikely to be the sole cause of avascular necrosis; however, mechanical stress to the forefoot from high-impact sports may precipitate a previous predisposition to this condition. Progression of attritional ligamentous injury may result in a crossover deformity, joint instability, and toe dislocation. Loss of flexibility can lead to chronic stiffness and loss in ROM. (See also the Medscape Reference article Freiberg Infraction.)

Athletes who suddenly and dramatically increase training activity are at risk of forefoot injury. Whether the increase is in time or intensity, athletes should increase their levels of activity gradually, and they should never exercise through the pain.

Long-distance runners, women, and athletes who diet to qualify for certain weight divisions may experience bone loss from nutritional deficiency, predisposing them to foot injury. A well-rounded diet is necessary for healthy tissues.

The selection of footwear and orthotic devices is an important part of foot care and injury prevention. Warm-up and passive stretching increase vascular supply and flexibility.

The primary symptom of metatarsalgia is pain at 1 or more of the metatarsal heads.[6, 7, 8, 9] Diffuse forefoot pain and midfoot pain are often present in athletes with combinations of high-impact inflammatory conditions.[2, 3]

The pain is typically aggravated during the mid-stance and propulsion phases of walking or running.

A history of a gradual, chronic onset is more common than an acute presentation. Chronic symptoms may be of gradual onset over 6 months.

A Morton neuroma (interdigital neuroma) produces symptoms of metatarsalgia due to irritation and inflammation of the digital nerve located in the web space between the metatarsal heads. Patients with a Morton neuroma may complain of toe numbness in addition to pain in the forefoot. The term Morton neuroma is a misnomer because no neuroma truly exists. Rather, the lesion results from a mechanical entrapment neuropathy. (See also the Medscape Reference articles Physical Medicine and Rehabilitation for Morton Neuroma and Surgery for Morton Neuroma.)

Palpable point tenderness at the distal end of the plantar metatarsal fat pad is a typical finding.

Pain and tenderness are experienced on the plantar surface of the metatarsal head, which is often accompanied by the development of a callus formation (plantar keratosis). (See also the Medscape Reference article Intractable Plantar Keratosis.)

Absence of pain in the interdigital space helps the clinician assess for the presence of a neuroma.

Patients with an interdigital neuroma have maximal tenderness between the web spaces.

Loss of sensation may be present in the adjacent toes.

In patients with interdigital neuromas, the pain is usually aggravated by the metatarsal squeeze test. Compression between the metatarsal heads may produce a painful click, known as a Mulder sign.

Although appearing clinically different from traumatic injuries to the first metatarsophalangeal joint, gout commonly presents with pain at the base of the first toe. Testing of uric acid levels, the erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) may be helpful in excluding gouty arthritis and other rheumatologic conditions in subtle cases. Otherwise, laboratory studies are of little benefit in the evaluation of metatarsalgia. (See also the Medscape Reference article Gout and Pseudogout.)

A radiographic foot survey is indicated as an initial imaging test and may be helpful in excluding other etiologies of forefoot pain.

Order repeat radiographs and a bone scan to assist the physician with diagnosing or excluding a metatarsal stress fracture. (See also the Medscape Reference article Metatarsal Stress Fracture.)

Ultrasonography provides useful information about possible pathologic conditions that may be responsible for pain in the metatarsal region of the foot, including bursitis, Morton neuroma, and joint effusions.[10, 11] (See also the Medscape Reference article Bursitis in Emergency Medicine.)

Yu and Tanner demonstrated that magnetic resonance imaging (MRI) is a powerful, noninvasive method for detecting and diagnosing many causes of pain in the metatarsal and midfoot regions, including conditions caused by trauma, circulatory disorders, arthritides, neuroarthropathies, and those that result in biomechanic imbalance.[12]

F-Scan (Tekscan, Inc, South Boston, Mass) is an objective measurement system that is used to assess plantar pressures, identify the location of peak pressures, and help with the molding and placement of orthotic devices that can be most effective in dispersing excessive localized forces.

A local digital nerve block just below the transverse tarsal ligament may be helpful in the diagnosis of an interdigital neuroma. Patients with an interdigital neuroma should receive relief after the injection.

Rehabilitation Program

Physical Therapy

The initial treatment includes regular icing and application of a pressure bandage (or RICE: rest, icing, compression, and elevation). Recommend non–weight-bearing ambulation for the first 24 hours, after which passive range-of-motion (ROM) and ultrasound treatments can be initiated. The use of metatarsal pads and other orthotic devices may provide relief, even in the early phases of treatment.[9, 13, 14]

Rehabilitation begins on the first day of injury, with the goal of restoring normal ROM, strength, and function. Long-axis distraction and dorsal/plantar glides of the metatarsophalangeal joint are self-mobilization techniques that can be used throughout the treatment process.

Occupational Therapy

Semi-rigid orthoses worn in supportive shoes have been shown to be effective treatment for metatarsalgia.[13] Supportive shoes worn alone, with or without soft orthoses, have not been shown to provide adequate pain relief.

Medical Issues/Complications

The patient should avoid disrupting the healing process; rather, the patient should perform stretching and strengthening exercises carefully. Likewise, the patient’s return to higher-level activity should be pursued gradually and with caution to prevent reinjury. However, this obvious decreased level of activity may not be acceptable to some athletes. The practitioner may need to reinforce the relationship between the pain and the activity and discourage the athlete from trying to run in spite of the pain.

Surgical Intervention

Successful metatarsal pain outcomes have been reported with oblique osteotomy.[15] The better outcomes are attributed to improved techniques to facilitate precise metatarsal positioning in different planes.

Other Treatment

Removing the callus (plantar keratosis) is not advised because the callus is a response to pressure and is not the primary disease. Temporary relief can be achieved by shaving down the callus; however, the clinician should avoid causing bleeding from excessive debridement and from the use of acids and other chemicals.

If the patient's symptoms are acute with a short duration, abnormal pronation of the subtalar joint can be the primary etiology. Use orthotic devices in these cases. Chronic symptoms respond better to a metatarsal bar that can be added to the running or athletic shoe.

Individuals with a pes cavus foot type who experience pain from metatarsalgia respond well to an orthotic device that provides total contact to the medial longitudinal arch because preventing collapse of the arch reduces the stress on the metatarsal heads. Patients with a Morton toe respond well to a rigid orthotic with an extension underneath the first metatarsal bone.

Rehabilitation Program

Physical Therapy

The primary focus of treatment is restoration of normal foot biomechanics and relief of pressure in the symptomatic area. Therapy must allow the inflammation to subside or resolve by relieving the repeated excessive pressure.

Once the individual is pain free, initiate isometric, isotonic, and isokinetic strengthening exercises. Passive ROM exercises can progress to active exercises as the inflammation resolves. Therapy to increase dorsiflexion ROM allows improved forward progression of the tibia over the foot, with reduced stress on the forefoot. Strengthening the toe flexor muscles may allow for greater weight-bearing capacity on the toes.

Recreational Therapy

Swimming is an excellent exercise for maintaining physical conditioning while the patient is in a restricted weight-bearing phase of healing.

Other Treatment (Injection, manipulation, etc.)

Patients with an interdigital neuroma component of injury can benefit from a nerve block in combination with administration of long-acting steroids. Individuals with primary metatarsalgia receive little benefit from such injections.

Rehabilitation Program

Physical Therapy

As the inflammation subsides, an orthotic device is often the only intervention that is required to maintain normal mechanical function. These orthoses are necessary to distribute force away from the site of injury. Patients should continue self-mobilization exercises, including long-axis distraction and dorsal/plantar glides.

Surgical Intervention

Shoe modification with an orthosis may be the only treatment required for metatarsalgia. In severe cases, surgical realignment of the metatarsal bones may be required to balance weight bearing among the metatarsal heads.

In cases where conservative treatment has failed to provide relief of symptoms, surgical intervention may be required, including operative synovectomy, arthroplasty, wedge osteotomies of the metatarsal bases, ligamentous release, and tendon transfer.

Many types of osteotomies have been described as possible surgical interventions for metatarsalgia.[15, 16, 17, 18, 19] Success and complications rates vary. The Weil osteotomy of the second and third metatarsals has been shown to be an effective and safe procedure for the treatment of central metatarsalgia.[16, 20]

Consultations

Consider referral to an orthopedic specialist if no improvement has been achieved after 3 months of treatment.

Other Treatment

The high pressure under the metatarsal heads can be reduced by applying metatarsal pads. In a double-blind study, tear-drop shaped, polyurethane metatarsal pads were applied by experienced physiatrists to a total of 18 feet.[9] As a result, there were significantly decreased maximal peak pressures and pressure time intervals during exercise that correlated with better pain and function outcomes.

The timetable for a patient's return to normal athletic function depends upon the nature of the injury and the specific demands of the particular sport. Resolution of the pathologic deficits that are associated with the injury includes restoration of flexibility, strength, aerobic fitness, good nutrition, and proprioception, which are required for each sport activity. Acceleration of physical activity should occur gradually and with stretching, both as a warm-up and warm-down.

Returning to play for most injured athletes exposes them to the same traumatic conditions that resulted in the original injury. Therefore, the individual must be completely healed, free of symptoms, and prepared for resuming the stress and trauma inherent to the sport. Track-and-field athletes should have normal orthokinetics, balance, and 90% of normal baseline strength before returning to play. Proper selection of running and training shoes is critically important to prevent reinjury.

The preventive goal should focus on eliminating abnormal friction or pressure. Orthotics, metatarsal pads, and callus care can be used to prevent muscular and stress imbalances. Callus care includes razor debridement and buffing, which enhance tissue elasticity.

Some foot problems may not be caused by disease but by improper footwear. Proper positioning of the foot within the shoe depends upon appropriate fitting, as no 2 feet are the same. Athletes who perform on hard surfaces should make certain that new shoes have adequate cushioning. Rubber heels and soles that absorb shock better than other materials are helpful for athletes who perform repetitive running and jumping on hard surfaces.

Nonsteroidal anti-inflammatory drugs, such as ibuprofen, are useful for the symptomatic relief of the pain of metatarsalgia; however, these agents rarely provide a long-term solution.

Class Summary

NSAIDS are most commonly used for the relief of mild to moderate pain. Although the effects of these agents in the treatment of pain tend to be patient specific, ibuprofen is usually the drug of choice (DOC) for initial therapy. Options include ketoprofen and naproxen and many other NSAIDs.

Ibuprofen (Motrin, Ibuprin)

DOC for patients with mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Ketoprofen (Oruvail, Actron, Orudis)

For relief of mild to moderate pain and inflammation.

Small dosages are initially indicated in small and elderly patients and in those with renal or liver disease. Doses over 75 mg do not increase therapeutic effects. Administer high doses with caution, and closely observe patient for response.

Naproxen (Anaprox, Naprelan, Naprosyn, Anaprox)

For relief of mild to moderate pain; inhibits inflammatory reactions and pain by decreasing activity of cyclooxygenase, which results in a decrease of prostaglandin synthesis