Calluses represent a dermatologic reaction to focal pressure. Ongoing pressure results in calluses developing into corns. Corns can be differentiated from warts when incised; warts will bleed, corns will not. The differential diagnosis includes syphilis, psoriasis, lichen planus, rosacea, arsenic poisoning, basal cell nevus syndrome, and malignancy. Treatment for corns is paring with a No. 15 blade to include removal of central keratin plug.
Plantar warts are common, contagious, and caused by the human papillomavirus. The diagnosis is clinical and the differential diagnosis includes corns and undiagnosed melanoma. Topical treatment with 15% to 20% salicylic acid is most effective. Nonhealing lesions should be referred to a dermatologist or podiatrist.
Onychocryptosis is characterized by increased inflammation or infection of the lateral or medial aspects of the toenail. This occurs when the nail plate penetrates the nail sulcus and subcutaneous tissue (usually in the great toe). Patients with underlying diabetes, arterial insufficiency, cellulitis, ulceration, or necrosis are at risk for amputation if treatment is delayed. Treatment depends on the type of inflammation. If toenail is uninfected, sufficient results will often be obtained with elevation of the nail with a wisp of cotton between the nail plate and the skin, daily foot soaks, and avoidance of pressure on the area. A second option (requiring digital block) is to remove a spicule of the nail and debride the nail groove. If granulation tissue or infection is present, partial removal of the nail is indicated. If the toenail is infected perform digital block and cut one-fourth or less of the nail with a longitudinal incision (including beneath the cuticle). A nonadherent bulky dressing should be placed, and the wound should be checked in 24 to 48 hours.
Pathologic bursae of the foot are categorized as follows: (1) noninflammatory, (2) inflammatory, (3) suppurative, and (4) calcified. Noninflammatory bursae become painful as a result of direct pressure, whereas inflammatory bursitis results from gout, syphilis, or rheumatoid arthritis. Suppurative bursitis results from spread of pyogenic organisms (often Staphylococcus aureus) from adjacent wounds. Complications include hygroma, calcified bursae, fistula, and ulcer formation. Treatment for severe septic bursitis includes intravenous antibiotics such as nafcillin 500 milligrams qid or oxacillin 500 milligrams qid. For further discussion, see Chapter 180 Acute Disorders of the Joints and Bursae.
The plantar fascia is connective tissue anchoring the plantar skin to the bone protecting the arch of the foot. Plantar fasciitis is the most common cause of heel pain due to overuse. Patients have point tenderness over the anterior–medial calcaneus, that is, worse on arising and after activity. The differential diagnosis includes abnormal joint mechanics, poorly cushioned shoes, Achilles tendon pathology, and rheumatoid disease. Treatment includes rest, ice, and nonsteroidal anti-inflammatory drugs (NSAIDs). Most cases are self-limited. Glucocorticoid injections are not indicated in the ED. Severe cases may require a short-leg walking cast and should be referred to a podiatrist or orthopedist.