Corns and Calluses

Corns and Calluses 

7 Interesting Facts of Corns and Calluses 

  1. •Corns and calluses are typically caused by thickening of the keratin layers of the epidermis due to excessive pressure exerted over a bony prominence of the foot.
  2. •Loss of the normal fat pad, improper footwear, toe deformities, increased activity level, and systemic diseases (rheumatoid arthritis) may contribute to the development of corns and calluses.
  3. •Callus refers to a large lesion with undefined boundaries and without a central core.
  4. •Corn refers to a smaller lesion with well-defined boundaries and a central core. Corns are divided into hard and soft corns.
  5. •Nonoperative treatment consists of modifying footwear, paring the excessive keratin layers, and applying padding to alleviate pressure. Patient education is also important.
  6. •Surgery may be indicated to correct bony deformity.
  7. •Corns and calluses have a tendency to recur unless the underlying pathology is properly addressed.

History

  • •Discomfort in normal footwear or when walking barefoot (advanced corn)
  • •Inquire about a history of Charcot-Marie-Tooth disease, other neurologic conditions (such as diabetic neuropathy), or systemic disease (rheumatoid arthritis), as these can be causes for the toe deformities associated with corns and calluses.
  • •May also be associated with older age, female gender, hallux valgus, and prolonged standing.

Physical Examination

  • •Observation
    • •Calluses are typically located on the plantar aspect of foot, mainly at the metatarsophalangeal joints, but may occur anywhere bony prominence exists.
    • •Hard corns are commonly located on the fibular aspect of the fifth toe or dorsal aspect of the proximal interphalangeal (IP) or the distal interphalangeal (DIP) joints.
      • •May be associated with hammertoe, mallet toe, or claw toe deformity
      • •Hyperkeratotic area with a lighter conical center (without underlying vessels)
    • •Soft corns present as maceration between the lesser toes, mainly between 4 and 5.
      • •A result of the absorption of extreme amounts of moisture from perspiration
      • •Sometimes reddish in appearance and may become infected
      • •These may be extremely painful.
  • Palpation
    • •Hard and soft corns eventually become tender.

Imaging

  • •Usually not necessary for initial treatment; clinical diagnosis
  • •Radiographs: weight-bearing anteroposterior, lateral, and oblique views of the foot
    • •In the case of an ulcerated lesion, may be used to identify osteomyelitis
    • •Helpful to view the structural deformities as the cause of the callus or corn

Differential Diagnosis

  • •Plantar warts: fine capillaries perpendicular to the surface, exhibit punctuate bleeding after trimming
  • •Skin ulceration: skin layer is destroyed and exposes underlying soft tissues or bone.
  • •Mycotic infection

Treatment

  • •At diagnosis
    • •Conservative management is appropriate.
      • •Reduction of hyperkeratotic area by paring with a scalpel
      • •Footwear adaptations (soft-soled shoes with large toe box)
      • •Padding of the symptomatic area or to offload excess pressure
      • •Toe sleeves or toe crests for dorsal corns on the IP joints of the toes
      • Instruct patient how to shave the callus/corn with pumice stone after soaking in warm water.
      • •Beware of salicylic acid on immunocompromised or neuropathic patients, as this can damage otherwise healthy skin.
  • •Later
    • •If the corn or callus cannot be controlled by conservative measures, surgical intervention may be warranted to correct underlying deformity.

When to Refer

  • •Failure of conservative measures warrants referral to an orthopaedic surgeon. In addition, concern for infection warrants referral.
  • •Surgical options include correction of the toe deformity and isolated condylectomy.
  • •Deformity correction varies based on the location of deformity (metatarsal shortening osteotomy for plantar callus vs. hammertoe correction for DIP/IP corns).
  • •If the examiner is not confident in excluding a true mycotic infection, referral to a dermatologist can be considered.

Prognosis

  • •Generally good when there is no infection associated with osteomyelitis

Troubleshooting

  • •Complications include bleeding after trimming the corn or callus, mycotic infection when maceration is not managed adequately, and, in rare cases, deeper infection with osteomyelitis of the phalanx.
  • •Infection with swelling, redness, and warmth of the toe combined with pain is an absolute indication for immediate referral. Under such circumstances, intravenous antibiotic therapy should be considered.

Patient Instructions

  • •Patients should be educated about the causes of corns and calluses.
  • •Shoes should have a wide toe box, be free of any seams over the areas of callus/corn, and be appropriately sized.
  • •Patients must be instructed in the use of a pumice stone to trim calluses without injuring healthy skin.

Seek Additional Information

  • Freeman DB: Corns and calluses resulting from mechanical hyperkaratosis. Am Fam Phys 2002; 65-11: pp. 2277-2280.
  • Jakeman A: The effective management of hyperkeratosis. Wound Essentials 2012; 1: pp. 65-73.
  • Spink MJ, Menz HB, Lord SR: Distribution and correlates of plantar hyperkeratotic lesions in older people. J Foot Ankle Res 2009; 2: pp. 8.
  • Tlougan BE, Mancini AJ, Mandell JA, et al.: Skin conditions in figure skaters, ice-hockey players and speed skaters: part 1—mechanical dermatoses. Sports Med 2011; 41 (9): pp. 709-719.
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