Metatarsalgia refers to pain in the forefoot under the metatarsal head region. Primary metatarsalgia is generally considered the result of mechanical overload of the metatarsal heads, whereas secondary metatarsalgia often has a rheumatic etiology. Primary metatarsalgia may be caused by hallux valgus, hallux rigidus, or sagittal plane first ray hypermobility, which causes a transfer of load to the lateral forefoot and lesser metatarsal heads (Fig. 90.1). A hammer toe with an associated dorsal contracture of a metatarsophalangeal (MTP) joint will cause a retrograde plantar flexion force on the metatarsal head (Fig. 90.2). Bunion surgery, with first metatarsal osteotomy resulting in excessive shortening or elevation of the first metatarsal and with resection of the base of the proximal phalanx of the hallux, is an iatrogenic cause of metatarsalgia [1]. Ankle equinus, leg length discrepancy, scoliosis, kyphosis, neuromuscular disorders, lower extremity trauma, or other foot surgery (elective or post-traumatic) may also result in increased forefoot pressures. Wearing of thin-soled high-heeled shoes may increase the risk for development of metatarsalgia. Although the relative risk of running barefoot or in “minimalist” shoes (compared with traditional running shoes) and developing metatarsalgia is not known, a case series of experienced runners who developed metatarsal stress fractures after transitioning to minimalist running footwear was recently reported [2]. Lieberman [3] has pointed out that runners who transition to barefoot or minimalist shoes may not have strong enough extensor muscles or metatarsal bones, which could lead to an increased risk of metatarsalgia or metatarsal stress fractures.

f90-01-9781455775774 — FIGURE 90.1 Cross-sectional view of metatarsal heads. Elevated first metatarsal head results in mechanical overload of lesser metatarsal heads.

f90-02-9781455775774 — FIGURE 90.2 Hammer toe with associated plantar plate tear. The hammer toe causes a retrograde plantar flexion force on the metatarsal head.

Secondary metatarsalgia has been associated with rheumatoid arthritis, psoriatic arthritis, reactive arthritis, and systemic lupus erythematosus. MTP joint synovitis may lead to weakening or rupture of the stabilizing structures around the joint, leading to dorsal subluxation of the toes on the lesser metatarsal heads [4]. Degenerative arthritis of the lesser MTP joint may be caused by Freiberg infraction (metatarsal head avascular necrosis).

Symptoms

Plantar forefoot pain is generally aggravated by weight bearing, is often worse during the propulsive phase of gait, and is often localized beneath the second metatarsal head or second MTP joint. Lesser MTP joint morning stiffness may be present. Neuritic radiating pain may occur from irritation, inflammation, or tethering of neighboring plantar intermetatarsal nerves.

Poorly defined pain in the forefoot is a common early symptom in patients with rheumatoid arthritis. Other symptoms include MTP joint symmetric swelling and stiffness after rest.

Physical Examination

The forefoot examination attempts to elicit pain on palpation directly beneath the metatarsal heads or MTP joints, commonly the result of mechanical overload from an unstable first ray or medial column. Pain elicited with lateral compression of neighboring metatarsal heads also suggests a plantar intermetatarsal neuroma. Stress fractures are commonly identified at the metatarsal neck, demonstrated by swelling, palpable pain, or bone fixation callus. Evaluate the excursion and pain of MTP joint passive range of motion and note the presence of swelling. Assess for first metatarsal hypermobility by applying a dorsiflexion force under the first metatarsal head. If hypermobility is present, the first metatarsal head will rise well above the second metatarsal head [5]. Examine for dorsal translation of the proximal phalangeal base on the metatarsal head (drawer test) to identify plantar plate or capsule disruption. Also check for Mulder sign, which may suggest a plantar intermetatarsal neuroma.

While the patient is standing, note the presence of forefoot deformities including hallux valgus, hammer toes, MTP joint dorsal contractures, and medial or lateral subluxation of the toes. The “paper pull-out test” to evaluate toe purchase is performed by asking the patient to flex the toe against a piece of paper placed on the floor under the toe. The test result is positive if the paper cannot be pulled out from under the toe. If there is a V-shaped alignment of adjacent toes noted while the patient is standing, indicative of web space widening, early synovitis [6], plantar intermetatarsal neuroma, or other space-occupying mass may be present. Weight-bearing bilateral or unilateral heel raise while standing barefoot often aggravates metatarsalgia pain. During gait examination, observe for early heel-off, antalgic gait, excessive or insufficient subtalar joint pronation, asymmetry, and lack of toe purchase. Inspect the skin for plantar calluses and their locations. Examine the shoe outsoles and insoles for signs of excessive or uneven wear indicative of areas of elevated pressure or abnormal foot mechanics.

Functional Limitations

Forefoot pain may limit standing, walking, and participation in high-impact activities, such as running or jumping. There will be a limitation to shoe style able to be worn comfortably. Metatarsalgia has its greatest impact on activities requiring prolonged standing or walking on hard floors (e.g., cashier, food preparation, or housekeeping jobs). Sales jobs requiring use of a dress shoe may be difficult. Walking speed may decrease while shopping or accessing public transportation. Recreational activities, such as walking, tennis, basketball, or running on a treadmill on an incline, may be particularly painful.