Definition

A clavus, or corn in layman's terms, is an overgrowth of thickened skin caused by repeated pressure on the skin. The clavus usually appears small on the skin's surface but can extend deep into the skin in an inverted cone-like shape. The clavus contains a build-up of dead skin cells. Clavus is particularly common on the toes and plantar surface as they have a flat and hairless skin surface.

There are 2 types of clavus: hard clavus, which often occurs on the surface or dorsum part of the toes, and soft clavus, which arises in spaces of the toes. Hard clavus tends to be dry and smaller in size and usually occurs on the rough surface areas of the skin where the skin is thickened or in areas of bone prominences on the feet. Meanwhile, the soft clavus tends to be white in color, with a more soft texture. Soft clavus may appear like open sores and are more common in the spaces of the toes or moist and sweaty areas of the skin. Both types of clavus are painful and usually caused by increased pressure on the skin from wearing ill-fitting shoes or other repeated pressure on the toes.

The clavus is sometimes compared to the callus. Both are often caused by repeated pressure on the skin, but they are not the same. The clavus is usually harder, smaller, and more painful than the callus. Callus, on the other hand, is not painful. Clavus is not a dangerous condition, but it can interfere with daily activities. Clavus is also more likely to affect women than men.

Causes

Pressure and friction from repetitive actions can cause clavus to develop and grow. Some sources of this pressure and friction include:

• Wearing ill-fitting shoes. Tight shoes and high heels can put pressure on the areas of your feet. If your footwear is too loose, your feet may repeatedly rub against the shoes. Your feet may also rub against the seams inside the shoes. 
• Not using socks. Wearing shoes and sandals without socks can cause friction on your feet, and ill-fitting socks can also cause friction.
• Playing musical instruments or using hand tools. Thickening of the skin on your hands can occur due to repetitive pressure from playing musical instruments, using hand tools, or writing.
• Movement or gait abnormalities that increase pressure on certain body areas can cause clavus.

Risk factor

Anyone from any age group (except infants who have not yet started walking) can develop clavus. However, clavus is particularly common in people over the age of 65. Some factors that may increase the risk of developing clavus include:

• Having foot deformities, such as:
• Bunion is an abnormal bony bump that forms at the base of your big toe joint. 
• Hammertoe, a deformity where your toes are curved like claws.
• Other foot abnormalities, such as bone spurs, can cause constant friction inside your shoes.
• Not using protective equipment for your hands, such as using hand tools without protective gloves, can expose your skin to excessive friction.
• Having gait abnormalities
• Wearing shoes with incorrect size, such as shoes that are too tight, too loose, or heels too high 
• Having a specific occupation, such as farmer or gardener
• Wearing ill-fitting socks or not wearing socks
• Walking barefoot
• Frequent cycling
• Repeatedly kneeling or resting elbows on a table 

Symptoms

Clavus can occur in any area of the body, but the most common locations for clavus are:

• Bottom of the foot (sole surface), above the arch of the toes
• The outside part of the fifth toe (little finger), where it rubs against the shoe
• Interdigital surface between the fourth and fifth toes

Some of the symptoms of clavus that you may feel include:

• There are hardened, thick parts of skin 
• Round or cone-shaped and may appear as bumps on the skin 
• Dry or scaly skin
• The thick part of skin feels painful, especially if given pressure, or feels annoying when walking or doing activities

Diagnosis

In diagnosing clavus, the physician will start by conducting a medical anamnesis with you. They will ask you about your symptoms and where the clavus occurred when the symptoms began. They will also look for any risk factors that may have contributed to the onset of the clavus. 

They will then perform a physical examination by directly inspecting the affected skin area. The physician may also palpate the clavus to assess its surface and structure and whether the patient feels pain when pressed. Basically, the diagnosis of a clavus can be made based on medical anamnesis and physical examination. There is usually no need for additional tests to diagnose a clavus.

Management

The primary treatment and therapy for clavus is to avoid activities that cause repeated friction on the affected skin area. Some steps you can take to treat clavus at home are:

• Use over-the-counter patches. Place the patch (plaster, etc.) to protect where the clavus has developed.
• Soak your hands or feet in warm, soapy water. This can soften the clavus, making it easier to remove the thickened skin.
• Scrub the thickened skin. Rub the clavus with a pumice stone or nail scraper during or after bathing to help remove the hardened skin layer. Do not use sharp objects to cut the skin, and do not use a pumice stone if you have diabetes.
• Moisturize the skin. Apply moisturizer to your hands and feet to help keep the skin soft.
• Wear comfortable shoes and socks. Stick with well-fitting, cushioned shoes and socks until your clavus is gone.

If the clavus persists or increases in pain despite your efforts, you may need medical management, such as:

• Cutting away excess skin. Your doctor may peel off the thickened skin or cut off the large clavus with a scalpel, which can usually be done in healthcare facilities. Do not attempt this yourself as it may cause infection.
• Clavus removal medication. Your doctor may also apply a patch containing 40% salicylic acid. The doctor will tell you how often you need to change this patch. You may also be prescribed salicylic acid in gel form to be applied over a larger area.
• Shoe inserts. If you have an underlying foot deformity, doctor may prescribe custom-made padded shoe inserts (orthotics) to prevent recurrent clavus.
• Surgery. In rare cases, your doctor may recommend surgery to correct the alignment of the bones that are causing repetitive friction.

Complications

Clavus is basically not a dangerous disorder and does not cause complications. However, clavus can cause pain and discomfort when you walk or do activities.

Prevention

To ensure your clavus does not develop or return after treatment, you must eliminate the conditions that cause it. Here are some tips to help eliminate friction and prevent clavus formation:

• Wear shoes and socks that fit properly. Ask the attendant to measure your feet to ensure the right footwear size, and then choose shoes that are neither loose nor tight.
• Trim your toenails. Long toenails can force your toes to push against your shoes, creating pressure that causes clavus to form over time.
• Use clavus pads. Pads that cover the clavus can help protect the area around it against excess pressure or friction. These pads are usually shaped like doughnuts and should be positioned so the clavus is in the center hole.
• Keep your feet clean. Wash your feet daily with soap and water and scrub gently.
• Keep your feet moisturized. Use foot cream regularly to prevent dryness and friction of the skin of the foot.

When to see a doctor?

Consult a doctor if your symptoms become more painful or there is no change despite trying several home treatments.

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