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Metatarsalgia is a general term for pain in the area of the metatarsophalangeal joint (ball of the foot). Most common causes include Freiberg disease, interdigital nerve pain (Morton neuroma), metatarsophalangeal joint pain, sesamoiditis,, and submetatarsal head fat pad atrophy typically associated with aging.
Freiberg Disease
(Freiberg Infraction)
Freiberg disease is avascular necrosis of the metatarsal head. Pain is most pronounced with weight bearing. Diagnosis is confirmed with x-rays. Treatment includes corticosteroid injections, immobilization, and orthotics.
Freiberg disease is caused by microtrauma at the metaphysis and growth plate. Avascular necrosis flattens the metatarsal head. The 2nd metatarsal head is most often affected. Freiberg disease is thought to occur more frequently among pubertal females and among people who have a short 1st metatarsal bone or long 2nd metatarsal bone, which increases stress on the 2nd metatarsal head and joint. The metatarsal joint tends to collapse, and activities that repetitively stress this joint, such as dancing, jogging, or running, may accelerate this process.
Symptoms and Signs
The pain is most pronounced in the forefoot at the metatarsal head with weight bearing, particularly when pushing off or when wearing high-heeled footwear. The metatarsophalangeal joint may also be swollen and have limited and painful passive range of motion.
Diagnosis
The diagnosis is confirmed with x-rays. Typically, the head of the 2nd metatarsal is widened and flattened, and the metatarsal joint is sclerotic and irregular.
Treatment
Corticosteroid injections and immobilization may help to alleviate acutely painful flare-ups. Long-term management may require orthoses with metatarsal bars and low-heeled footwear to reduce stress on the 2nd metatarsal head and joint. Corticosteroid injections can be tried, and, rarely, surgical excision of the metatarsal head may be necessary to relieve recalcitrant pain.
Interdigital Neuralgia
(Morton Neuroma/Morton Neuralgia)
Interdigital nerve irritation (neuralgia) or persistent benign enlargement of the perineurium (neuroma) can cause pain, which may be nonspecific, burning, or lancinating, or a foreign body sensation. Diagnosis is usually clinical. Treatment may involve correction of footwear, local injection, or sometimes surgical excision.
The interdigital nerves of the foot travel beneath and between the metatarsals, extending distally to innervate the toes. Neuralgia of the interdigital nerve along its distal innervation near the ball of the foot develops primarily as a result of improper or constrictive footwear or, less commonly, nerve traction resulting from abnormal foot structure. As a result of chronic repetitive trauma, a benign thickening of the nerve develops (Morton neuroma).
Symptoms and Signs
Interdigital neuralgia is characterized by pain around the metatarsal heads or the toes. Early interdigital neuralgia often causes an occasional mild ache or discomfort in the ball of the foot, usually when wearing a specific shoe, such as those that are too narrow at the front. Neuralgia is usually unilateral. As the condition progresses, the nerve thickens. The pain becomes worse, often with a burning or lancinating quality or paresthesias. In time, patients are unable to wear most shoes. While walking, patients often falsely sense a pebble in their shoes, which they take off for relief. Neuroma most frequently affects the 3rd interspace. Only slightly less common is involvement of the 2nd interspace. Sometimes both interspaces or feet are involved simultaneously.
Diagnosis
The symptoms are often specific, and the diagnosis is confirmed by tenderness on plantar palpation of the interdigital space and reproduction of the radiating burning pain by squeezing the space. Although MRI does not usually confirm neuroma, it may be useful to rule out other interspace lesions or arthritis causing similar symptoms.
Treatment
Neuralgia of recent onset usually resolves quickly with properly fitting shoes and insoles or with local anesthetic injection. In contrast, neuromas may require one or more perineural infiltrations of long-acting corticosteroids with a local anesthetic. Injection is at a 45° angle to the foot, into the interspace at the level of the dorsal aspect of the metatarsophalangeal joints. An appropriate orthotic, rest, cold packs, and properly fitting shoes often relieve symptoms. Nerve ablation techniques, such as injecting 20% alcohol with a local anesthetic directly into the nerve with ultrasonographic guidance, or cryogenic freezing of the nerve may help relieve symptoms. If other treatments are ineffective, excision often brings complete relief. Another neuroma occasionally develops at the site of nerve excision (amputation or stump neuroma) ,which may require additional surgery.
Key Points
Metatarsophalangeal Joint Pain
Metatarsophalangeal joint pain usually results from tissue changes due to aberrant foot biomechanics. Symptoms and signs include pain with walking and tenderness. Diagnosis is clinical; however, infection or systemic rheumatic diseases (eg, RA) may need to be excluded by testing. Treatment includes orthotics, sometimes local injection, and occasionally surgery.
Metatarsophalangeal joint pain most commonly results from misalignment of the joint surfaces with altered foot biomechanics, causing joint subluxations, flexor plate tears, capsular impingement, and joint cartilage destruction (osteoarthrosis). Misaligned joints may cause synovial impingement, with minimal if any heat and swelling (osteoarthritic synovitis).
The 2nd metatarsophalangeal joint is most commonly affected. Usually, inadequate 1st ray (1st cuneiform and 1st metatarsal) function results from excessive pronation (the foot rolling inward and the hindfoot turning outward or everted), often leading to capsulitis and hammer toe deformities. Overactivity of the anterior shin muscles in patients with pes cavus (high arch) and ankle equinus (shortened Achilles tendon that restricts ankle dorsiflexion) deformities tends to cause dorsal joint subluxations with retracted (clawed) digits.
Metatarsophalangeal joint subluxations also occur as a result of chronic inflammatory arthropathy, particularly RA. Inflammatory synovitis and interosseous muscle atrophy in RA lead to subluxations of the lesser metatarsophalangeal joints as well, resulting in hammer toe deformities. Consequently, the metatarsal fat pad, which usually cushions the stress between the metatarsals and interdigital nerves during walking, moves distally under the toes; interdigital neuralgia or Morton neuroma may result. To compensate for the loss of cushioning, adventitial calluses and bursae may develop.
Metatarsophalangeal joint pain may also result from functional hallux limitus, which limits passive and active joint motion and usually occurs at the 1st metatarsophalangeal joint. Patients usually have foot pronation disorders that result in elevation of the 1st ray with lowering of the medial longitudinal arch during weight bearing. As a result of the 1st ray elevation, the proximal phalanx of the great toe cannot freely extend on the 1st metatarsal head; the result is jamming at the dorsal joint leading to osteoarthritic changes and loss of joint motion. Over time, pain may develop. Another cause of 1st metatarsophalangeal joint pain due to limited motion is direct trauma with stenosis of the flexor hallucis brevis, usually occurring within the tarsal tunnel. If pain is chronic, the joint may become less mobile with an arthrosis (hallux rigidus), which can be debilitating.
Acute arthritis can occur secondary to systemic arthritides such as gout, RA, and spondyloarthropathy.
Symptoms and Signs
Symptoms include pain on walking. Dorsal and plantar joint tenderness is usually present on palpation and during passive range of motion. Mild swelling with minimal heat occurs in osteoarthritic synovitis. Significant warmth, swelling, or redness suggests inflammatory arthropathies or infection.
Diagnosis
Metatarsophalangeal joint pain can usually be differentiated from neuralgia or neuroma of the interdigital nerves by the absence of burning, numbness, tingling, and interspace pain, although these symptoms may result from joint inflammation; if so, palpation can help with differentiation.
Monarticular heat, redness, and swelling indicate infection until proven otherwise, although gout is more likely. When warmth, redness, and swelling involve multiple joints, evaluation for a systemic cause of joint inflammation (eg, gout, RA, viral-associated arthritis, enteropathic arthritis) with a rheumatic disease assessment (eg, antinuclear antibodies, rheumatoid factor, ESR) is indicated.
Treatment
Foot orthoses may help to redistribute and relieve pressure from the noninflamed joints. With excess subtalar eversion or when the feet are highly arched, an orthotic that corrects these abnormal alignments should be prescribed. Shoes with rocker sole modifications may also help. For functional hallux limitus, orthosis modifications may further help to plantarflex the 1st ray to improve metatarsophalangeal joint motion and reduce pain. If the 1st ray elevation cannot be reduced by these means, an extended 1st ray elevation pad may be helpful. For more severe limitation of 1st metatarsophalangeal motion or pain, the use of rigid orthoses, carbon fiber plates, or external shoe bars or rocker soles may be necessary to reduce motion at the joint. Surgery may be needed if conservative therapies are ineffective. If inflammation (synovitis) is present, injection of a local corticosteroid/anesthetic mixture may be useful.
Key Points
Sesamoiditis
Sesamoiditis is pain at the sesamoid bones beneath the head of the 1st metatarsal, with or without inflammation or fracture. Diagnosis is usually clinical. Treatment is usually modification of footwear and orthotics.
The 2 semilunar-shaped sesamoid bones aid the foot in locomotion. The medial bone is the tibial sesamoid, and the lateral bone is the fibular sesamoid. Direct trauma or positional change of the sesamoids due to alterations in foot structure (eg, lateral displacement of a sesamoid due to lateral deviation of the great toe) can make the sesamoids painful. Sesamoiditis is particularly common among dancers, joggers, and people who have high-arched feet or wear high heels. Many people with bunions have tibial sesamoiditis.
Symptoms and Signs
The pain of sesamoiditis is beneath the head of the 1st metatarsal; the pain is usually made worse by ambulation and may be worse when wearing thin-soled or high-heeled shoes. Occasionally, inflammation occurs, causing mild warmth and swelling or occasionally redness that may extend medially and appear to involve the 1st metatarsophalangeal joint. Sesamoid fracture can also cause pain, moderate swelling, and possibly inflammation.
Diagnosis
With the foot and 1st (big) toe dorsiflexed, the examiner inspects the metatarsal head and palpates each sesamoid. Tenderness is localized to a sesamoid, usually the tibial sesamoid. Hyperkeratotic tissue may indicate that a wart or corn is causing pain. If inflammation causes swelling around the 1st metatarsophalangeal joint, arthrocentesis is usually indicated to exclude gout and infectious arthritis. If fracture, osteoarthritis, or displacement is suspected, x-rays are taken. Sesamoids separated by cartilage or fibrous tissue (bipartite sesamoids) may appear fractured on x-rays. If plain x-rays are equivocal, MRI may be done.
Treatment
Simply not wearing the shoes that cause pain may be sufficient. If symptoms persist, shoes with a thick sole and orthotics are prescribed and help by reducing sesamoid pressure. If fracture without displacement is present, conservative therapy may be sufficient and may also involve immobilization of the joint with the use of a flat, rigid, surgical shoe. NSAIDs and injections of a corticosteroid/local anesthetic solution can be helpful. Although surgery may help in recalcitrant cases, it is controversial because of the potential for disturbing biomechanics and mobility of the foot. If inflammation is present, treatment includes conservative measures plus local infiltration of a corticosteroid/anesthetic solution to help reduce symptoms.
Key Points
Last full review/revision December 2012 by Kendrick Alan Whitney, DPM
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