Forefoot Pain

Clinical appearance

Anterior (front) foot pain may have articular, neural, and bone causes (Table 16) (40,41). In hallux valgus, fibular deviation of the big toe often results in overlapping toes and severe metatarsalgia. Because it is caused by pointy-toed shoes and elevated heels, hallux valgus is almost entirely confined to women. Hallux rigidus is a degenerative condition in which a cartilaginous/bony ridge prevents dorsiflexion of the big toe. Ligamentous failure of the second metatarsophalangeal (MTP) joint is an obscure condition, albeit well-recognized by foot surgeons, in which instability results in premature osteoarthritis of the joint. A collapsed transverse metatarsal arch causes inordinate metatarsal head stress and pain. Morton's neuroma, a poorly understood tender thickening of the digital nerve between the third and fourth toes or the second and third toes, causes forefoot pain. Tarsal tunnel syndrome, the result of entrapment of the posterior tibial nerve by tenosynovitis, exostosis, aberrant muscle bellies, or other causes, leads to diffuse plantar forefoot pain and paresthesias (42). An important predisposing factor is a valgus deviation of the heel. Sympathetic dystrophy occasionally complicates this syndrome. Sensory neuropathies, such as diabetic neuropathy, may also cause distressing plantar pain. Finally, bone insufficiency metatarsal fractures are a prominent cause of forefoot pain in older individuals with osteoporosis as well as in runners.

Differential diagnosis

A careful physical examination usually yields the cause of forefoot pain. In articular disease, tenderness is sharply localized to the MTP joint(s). Morton's neuroma is best identified by 2-finger compression, one dorsal and one plantar at the symptomatic intermetatarsal space. The neuroma may be felt as a tender fusiform swelling under the plantar skin. In the tarsal tunnel syndrome, percussion in back of the medial malleolus causes showers of plantar paresthesias. Metatarsal fractures are best detected by 2-finger palpation. These are characteristically placed near the metatarsal heads.

Treatment

Forefoot pain is usually the result of faulty footwear. An extra wide, extra deep shoe may be all that is required in hallux valgus; however, patients often refuse to wear such unsightly shoes. If symptoms are severe, orthopedic referral for surgical correction of the deformity is warranted. Surgical consultation should also be requested in patients with an unstable second MTP joint, stress fractures, and tarsal tunnel syndrome. The best form of treatment of Morton's neuroma has not been established. Some authorities favor its surgical removal, and there are technical considerations that may decrease the rate of recurrence. Others believe that initial treatment with 1-3 corticosteroid infiltrations results in a cure in 50% of cases. A controlled trial comparing the two procedures is needed.

Role of the primary care physician

Primary care physicians should be able to prevent many instances of forefoot pain simply by explaining the characteristics of sound footwear. A patient with Morton's neuroma should be referred to a specialist for corticosteroid injections. Systemic inflammatory conditions such as rheumatoid arthritis can begin with MTP joint arthritis and could mimic Morton's neuroma.

Key issues

Forefoot pain may have an articular, osseous, or neurogenic basis. The two most common painful conditions are hallux valgus, caused by faulty footwear, and metatarsalgia from flat feet.