AUTHOR AND EDITOR INFORMATION

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

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• Introduction
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• Differentials
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• Follow-up
• Miscellaneous
• Multimedia
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Background

Clavus is a thickening of the skin due to intermittent pressure and frictional forces. These forces result in hyperkeratosis, clinically and histologically. This extensive thickening of the skin may result in chronic pain, particularly in the forefoot; in certain situations, this thickening may result in ulcer formation. The word clavus has many synonyms and innumerable vernacular terms, some of which are listed in the Table below; these terms describe the related activities that have induced clavus formation.

Synonyms include the following: callosity, a hyperkeratotic response to trauma; corn, heloma, or a circumscribed hyperkeratotic lesion that may be hard (ie, heloma durum) or soft (ie, heloma molle); and callous, callus, or a diffusely hyperkeratotic lesion. Localized callosities of the soles, which do not resolve, are termed plantar callus, heloma, tyloma, keratoma, or plantar corn.¹ When callosities occur over 1 or more lateral metatarsals, they are termed intractable plantar keratoses.²

Clinically, all these lesions look like hyperkeratotic or thickened skin. Maceration and secondary fungal or bacterial infections are a common overlying feature in heloma molle and diabetes. Plantar helomas tend to have a central keratin plug, which, when pared, reveal a clear, firm, central core. The most common sites for clavus formation are the feet, specifically the dorsolateral aspect of the fifth toe for heloma durum, in the fourth interdigital web of the foot for heloma molle, and under the metatarsal heads for calluses.³

Pathophysiology

The shape of the hands and feet are important in clavus formation. Specifically, the bony prominences of the metacarpophalangeal and metatarsophalangeal joints often are shaped in such a way as to induce overlying skin friction. As clavus formation ensues, friction against the footwear is likely to perpetuate hyperkeratosis. Toe deformity, including contractures and claw, hammer, and mallet-shaped toes, may contribute to pathogenesis. Bunionettes, ie, callosities over the lateral fifth metatarsal head, may be associated neuritic symptoms due to compression of the underlying lateral digital nerves. Furthermore, Morton toe, in which the second toe is longer than the first toe, occurs in 25% of the population; this may be one of the most important pathogenic factors in a callus of the common second metatarsal head, ie, an intractable plantar keratosis. Chronic or repetitive motion may also induce clavus formation, as is seen in computer users (ie, "mousing" callus).

Frequency

United States

The clavus is a common disorder because of the frequency of usage of occlusive footwear and participation in repetitive activities, such as running.

Mortality/Morbidity

Extensive thickening of the skin may result in chronic pain, particularly in the forefoot; in certain situations, ulcer formation may result. Clavus may be a sign of underlying neuropathy due to diabetes or neuroborreliosis, or due to the deformities of rheumatoid arthritis. In the case of neuropathy, a clavus may hide ulceration or denote abnormal neurovasculature of the feet. In the case of rheumatoid arthritis, clavus may enhance the pain of deformed joints.

Race

Any race may be affected.

Sex

Clavus is more common in women than in men because of their use of occlusive and poorly fitted footwear.

Age

Anyone can have a clavus, but most individuals acquire the risk factors for clavus formation after puberty because of the onset of traumatic footwear use, repetitive motion injuries, and progressive foot deformities.

CLINICAL

Section 3 of 11  

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History

A clavus forms because of inappropriate distribution of pressure onto a specific site, usually of the foot. A localized callosity of the soles, which do not resolve, are termed plantar callus, heloma, tyloma, keratoma, or plantar corn. When callosities occur over one or more lateral metatarsals, they are termed intractable plantar keratoses.

Physical

Clinically, all these lesions look like hyperkeratotic or thick skin; maceration and secondary fungal or bacterial infections are a common overlying feature in heloma molle and diabetes. Plantar helomas tend to have a central keratin plug, which, when pared, reveal a clear, firm, central core. The most common sites for clavus formation are the feet, specifically the dorsolateral aspect of the fifth toe for heloma durum, in the fourth interdigital web of the foot for heloma molle, and under the metatarsal heads for calluses.

• Examination of patients should include assessment of the types of footwear worn, activities performed, gait, and current home therapy or previously prescribed therapy.
• Lesions should be palpated and pared to look for underlying blood vessels (black dots or pinpoint bleeding), which are seen in warts, and to look for underlying ulcerations, as seen in neurovascular ulcerations (especially in patients with diabetes).
• Paring of callosities or corns, as opposed to plantar warts, should reveal normal dermatoglyphics.
• Callosities are generally more painful with direct pressure, whereas warts are more painful with lateral pressure.
• Pedobarographic studies are pressure assessments that may be used to detect an altered distribution of foot pressure. MRI may delineate diabetic foot problems more clearly.
• Biopsy of lesions reveals hyperkeratosis and, occasionally, mucin deposition.

Causes

• Conditions associated with clavus formation include the following:
• • Advanced patient age
  • Amputation (ie, stump callosities)
  • Use of a brace or orthopedic stabilizing product
  • Bulimia nervosa
  • Diabetes mellitus with associated peripheral neuropathy
  • Doxorubicin toxicity
  • Keratoderma palmaris et plantaris
  • Obesity
  • Pachyonychia congenita⁴
  • Rheumatoid arthritis⁵
  • Sensory neuropathies, including neuroborreliosis
  • Tethered spinal cord syndrome⁶
  • Vascular occlusion syndromes⁷
  • Warts (ie, verruca vulgaris)¹
• Faulty mechanics: Irregular distribution of pressure and repetitive motion injury (especially in athletes) are believed to be the main inciting causes; however, inappropriately shaped or constrictive footwear in the presence of bony prominences (eg, talar bone prominences) may exacerbate clavus formation. Furthermore, some disorders may alter the shape or sensation of the soles of the feet. Bony prominences and faulty foot mechanics then allow clavus formation to continue.
• Rheumatoid arthritis: About 17% of patients with rheumatoid arthritis present with intractable foot pain. Chronic arthritis leads to foot deformities and consequent callus formation. Bleeding into callosities in patients with rheumatoid arthritis may be a sign of rheumatoid angiitis.
• Diabetes mellitus: In patients with diabetes, chronic callosities in the presence of neurovascular deterioration may lead to ulcerations and superinfections.
• Obsessive-compulsive disorder (pseudo-knuckle pads)
• Ectopic nail

DIFFERENTIALS

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Other Problems to be Considered

Gout
Hypertrophic lichen planus
Interdigital neuroma
Lichen simplex chronicus
Palmoplantar keratoderma
Keratosis punctata of palmar creases
Porokeratosis plantaris discreta
Porokeratosis palmoplantaris et disseminatum
Non-Herlitz junctional epidermolysis bullosa

WORKUP

Section 5 of 11  

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Lab Studies

• Blood glucose testing is required when paring reveals an ulcer or when diabetes mellitus is suspected. Rheumatoid factor testing for deformities consistent with rheumatoid arthritis may be indicated.

Imaging Studies

• Imaging studies are required only to detect underlying bony abnormalities
• Studies may include radiography, and occasionally, CT scanning of the affected area with bone window settings.

Other Tests

• Pedobarographic studies are pressure assessments that may be used to detect an altered distribution of foot pressure.

Procedures

• Biopsy of the lesions reveals hyperkeratosis and, occasionally, mucin deposition. Paring of the clavus can relieve pressure temporarily.
• Biopsy may be helpful in considering some of the other differential diagnoses, such as warts.
• Biopsy can be performed to differentiate clavus from porokeratosis palmoplantaris et disseminatum or discreta. These disorders occurred in those aged 20-40 years who have hyperkeratotic plaques on the palms and soles. Biopsy shows a cornoid lamella.

Histologic Findings

Histopathology reveals thickened stratum corneum (ie, compact orthokeratosis).

TREATMENT

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Medical Care

Treatment should be aimed at reducing symptoms such as pain and discomfort with walking. Paring of the lesions immediately reduces pain. Once the etiology of the foot pressure irregularity is determined, attempts at pressure redistribution should be made. The use of orthotics and conservative footwear with extra toe space are often beneficial. When all else fails, surgery may be performed.

• If abnormal dermatoglyphics or pinpoint bleeding is seen, wart therapy is initiated. If normal dermatoglyphics are noted, salicylic acid compounds and orthotics may be beneficial.
• Relief of symptoms may be achieved by thinning and cushioning of the involved lesions.
• • Paring of the lesions immediately relieves pain, especially with helomas. Lesions may be maintained in this state if the patient uses short soaks and pumice stone debridement at home. Debridement may be enhanced with the use of keratolytic agents, such as ureas, alpha-hydroxy acid (eg, glycolic, malic, or lactic acid), or beta-hydroxy acid (eg, salicylic acid).
  • Self-adhesive pads are most effective for reducing thick lesions, whereas lotions, creams, and medicaments in petrolatum are best for maintenance. Most salicylic acid compounds are 10-17%. High concentrations of salicylic acid (eg, 40%) may lead to severe maceration, and in patients with diabetes, it may lead to frank foot ulcerations. Intralesional Kenalog and topical vitamin A acid compounds also may reduce localized hyperkeratosis. Kenalog can lead to localized hypopigmentation.
  • A carbon dioxide laser can be used to pare deep lesions.
• Reduced friction may be accomplished with the use of silicone-lined sleeves on the toes, padding, and, in select cases, silicone or collagen injections³ over the bony prominence in question.
• • Lamb's wool may be beneficial in interdigital corns. Pads or permanent insoles, which place pressure proximal to the metatarsal head, relieve stress on the region. Insoles may be made of silicone or soft plastics.
  • Shoes with extra length are required for toe deformity, and shoes with extra width are required for lateral toe callosities. Shoes should be soft inside without seams that rub or press. Orthotics can be placed in the shoe for patients with abnormalities of the foot, such as cavovarus. Orthotics can be created by using insoles made to correct deformities noted on dynamic pressure molds. Reduction of heel height may be helpful for patients with metacarpal head callosities.⁸

Surgical Care

Surgical options should be used when only conservative measures fail.

• Chronic foot pain despite conservative therapy is the number one indication for surgery.
• Surgical corrections for claw, hammer, and mallet toes are simple procedures.
• Shaving of prominent condyles of bony prominences may be beneficial particularly on the fifth digit.
• Arthroplasty of the fifth toe interphalangeal joint also may be performed.
• Metatarsal condylectomy or chevron osteotomy may be performed to relieve metatarsal head pressure.
• • These procedures generally are performed on multiple joints simultaneously to prevent imbalances, which may be induced by single condylectomy.
  • Induced imbalance causes transfer lesions, ie, clavus formation of a new site on the foot.
• Mann and DuVries described the use of a combination of arthroplasty and condylectomy. This combination results in 95% clearance, with only a 13% occurrence of transfer lesions.
• When thinning of the plantar fat pads is contributory to the formations of callosities, injectable silicone can be used on the soles underneath the callosities and corns to reduce pressure related callous formation.

Consultations

• An orthopedist and a podiatrist can be helpful in adjusting abnormalities of gait or pressure distribution.
• Dermatologists are best consulted to assess for the possibility of other disorders in the differential diagnosis, especially warts and keratoderma.

Diet

No special diet is required; however, weight loss relieves some of the foot pressures involved.

Activity

Adjustment of the footwear and the use of special insoles aid in the maintenance of full mobility and eliminate the need for activity limitation.

MEDICATION

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• Differentials
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• References

Debridement may be enhanced with the use of keratolytic agents, such as ureas, alpha-hydroxy acid (eg, glycolic, malic, or lactic acid), or beta-hydroxy acid (eg, salicylic acid). The use of these agents is not recommended in pregnant women and young children. Most salicylic acid compounds are 10-17%. High concentrations of salicylic acid (eg, 40%) may lead to severe maceration and frank foot ulcerations in patients with diabetes. Self-adhesive pads are most effective for reducing thick lesions, whereas lotions, creams, and medicaments in petrolatum are best for maintenance. Intralesional Kenalog and topical vitamin A acid compounds also may reduce localized hyperkeratosis. Kenalog may be injected during pregnancy because of its limited absorption; however, it can lead to localized hypopigmentation. Topical vitamin A derivatives are not intended for use in women who are pregnant or intending to become pregnant because their safety ranges from category C to category X.

Drug Category: Keratolytics

These agents cause cornified epithelium to swell, soften, macerate, and then desquamate. Commonly used agents include urea, alpha-hydroxy acids (eg, lactic acid, glycolic acid), and beta-hydroxy acids (eg, salicylic acid).

Drug Category: Intralesional corticosteroids

These drugs have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.

Drug Category: Retinoids

Retinoids decrease the cohesiveness of abnormal hyperproliferative keratinocytes, and they may reduce the potential for malignant degeneration. Retinoids modulate keratinocyte differentiation.

These agents are not specifically approved for use in clavus therapy. Only tretinoin has been shown to be useful for clavus therapy in the topically applied form. These agents cause the skin to peel by loosening of keratinocyte adhesion. Irritation and discomfort are limiting adverse effects.

FOLLOW-UP

Section 8 of 11  

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• Follow-up
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• References

Further Inpatient Care

• Further inpatient care is not required unless surgical adjustments are needed.
• A patient with diabetes who has neuropathic ulcers and overlying clavus formation may require further care.
• Rheumatoid arthritis patients may benefit more from surgical interventions than callous debridement. Forefoot arthroplasty and first metatarsophalangeal joint implants may improve clavus formation and rheumatoid foot pain long-term.
• Measurement of the foot for orthoses is beneficial in the case of multiple clavi.

Further Outpatient Care

• Numerous contributory factors may result in thickened skin on the feet. Factors such as occupation, athletic pursuits, footwear, underlying bony abnormalities, and problems with general health may contribute to clavus formation.
• Etiologic factors must be carefully assessed before treatment can be given.
• Symptomatic relief can be achieved by thinning the hyperkeratotic lesions and by using cushions or insoles, which reduce pressure on the affected areas.
• Surgery can be an adjunctive treatment in those patients with intractable clavus formation and chronic foot pain.
• Using a combination of modalities and reducing the pressure of footwear ultimately reduces the appearance and discomfort of the clavus.

In/Out Patient Meds

• The use of keratolytic agents and retinoids is advised when clavus formation causes discomfort or other problems.

Deterrence/Prevention

• Clavus formation is a common painful frictional disorder that results in hyperkeratosis.
• Multiple methods to reduce friction and thus prevent recurrences are described in Medical Care and Further Outpatient Care.

Complications

• Patients, particularly patients with diabetes, may have ulcerations from chronic pressure. This can lead to infection and cellulitis.
• Maceration and tinea pedis also may occur.

Prognosis

• Chronic clavus generally occurs because of the difficulty in removing inciting factors in most situations.

Patient Education

• Patients must be taught to wear less traumatic footwear, such as shoes with a wide toe space.
• Using inner soles, lowering the heel (if second metatarsal head lesions are present), and preventing the repetitive injuries that cause occupational clavus formation may be helpful.
• For excellent patient education resources, visit eMedicine's Foot Care Center. Also, see eMedicine's patient education article Corns and Calluses.

MISCELLANEOUS

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Medical/Legal Pitfalls

• The clavus is a disease that is unlikely to be associated with any medicolegal risks or complications.
• However, in patients with diabetes or poor circulation in the lower extremity, therapy should be advanced slowly to avoid complications that warrant medicolegal intervention.
• • In this setting, avoiding any excess risk of superinfections is prudent.
  • This precaution generally is accomplished by using aseptic procedures and/or prophylactic antibiotics (when procedures involve the dermis) and by avoiding the use of harsh topicals in patients with neuropathy who might be unable to determine if any secondary adverse effects are occurring.
• MRI of the foot may aid in defining underlying diabetic foot disease.

Special Concerns

• Patients with diabetes and patients with rheumatoid arthritis are particularly at risk problems because of the association with neuropathic ulcerations and chronic foot deformities.
• In either situation, special consideration of the underlying disorder is required.

MULTIMEDIA

Section 10 of 11  

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• Multimedia
• References

Media file 1:  Screwdriver operator's callus (ie, clavus).
	View Full Size Image
Media type:  Photo

REFERENCES

Section 11 of 11

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• References

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25. Murray HJ, Young MJ, Hollis S, Boulton AJ. The association between callus formation, high pressures and neuropathy in diabetic foot ulceration. Diabet Med. Nov 1996;13(11):979-82. [Medline].
26. O'Goshi KI, Aoyama H, Tagami H. Mucin deposition in a prayer nodule on the forehead. Dermatology. 1998;196(3):364. [Medline].
27. Scott MJ Jr, Scott NI, Scott LM. Dermatologic stigmata in sports: weightlifting. Cutis. Aug 1992;50(2):141-5. [Medline].
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Article Last Updated: Jan 11, 2007