Foot and Ankle Skin Ulcers
What is a Skin Ulcer?
Skin ulcers are open wounds or sores that can form anywhere on the body. They are quite common on toes, feet, and ankles. They come in different shapes, sizes, and depths. Sometimes they are superficial, limited to only the outermost layers of the skin called the epidermis and dermis. However, some ulcers can extend deeper down to the fatty layer underneath the skin called the hypodermis or subcutaneous tissue layer. More rarely they can extend all the way down to tendon, joints, or bone. Unfortunately, any opening in the skin provides a portal of entry for bacteria which can then cause infection. The majority of diabetic amputations are preceded by ulcers which lead to infection. About 15% of diabetics will develop a foot ulcer in their lifetime. The good news is that many ulcers can be prevented. See our topics on diabetic foot care for more information on ulcer prevention.
What Causes Toe, Foot, or Ankle Ulcers?
There are many different causes of ulcers that occur on the toes, feet, or ankles. The three most common causes that we treat are neuropathic ulcers, venous stasis ulcers, and ischemic ulcers.
- Neuropathic ulcers occur in conjunction with peripheral neuropathy. This is most commonly seen in uncontrolled diabetics, but can also occur for many other reasons including vitamin deficiencies (ie. vitamin B12), alcoholic neuropathy, and idiopathic neuropathies. These types of wounds are caused by pressure, usually on the ball of the foot or tips of toes. Those with bunions, hammertoes, or other types of foot deformities/prominences are at increased risk. Neuropathic ulcers are often preceded by corns, calluses, or blisters that can be caused by poor fitting shoes. Many people with neuropathy lose the sensation in their feet and do not feel the normal pain response that would alert them that something is wrong. As a result, many of these wounds many have little to no pain and go undetected.
- Venous stasis ulcers are caused by incompetent valves in the leg veins which allow blood to pool in the vessels. This increased fluid pressure causes chronic swelling and damages the skin over time. They usually occur on the calves or inside/outside of the ankles but can happen on feet and toes as well. They are frequently preceded by chronic swelling (aka edema) in the legs, discoloration, blisters, weeping fluid and/or varicose veins. They often have symptoms of itching and/or pain but may be painless if neuropathy is present as well.
- Ischemic ulcers are caused by severely diminished arterial blood flow in the lower extremities. These usually occur on the outside of the ankle, back of the heel, or tips of the toes. Essentially, the tissues are starved of oxygen and nutrients causing death of the skin cells and soft tissues. These wounds are often very painful and may be preceded by frequent cramping of the muscles in the affected leg at night or when walking. If this condition progresses it can lead to gangrene. Those with diabetes or a history of tobacco use are at increased risk.
Treatment of Ulcers
Neuropathic Ulcers: The primary treatment for these wounds is to eliminate the pressure that caused the wound in the first place. If the wound is on the bottom of the foot (which most are) then complete non-weight bearing with crutches, a wheelchair, or knee scooter typically leads to the fastest healing in conjunction with good wound care and regular dressing changes. Unfortunately, many patients are unable or unwilling to be non-weight bearing. There are alternatives including special shoes, walking boots, or even total contact casts which allow walking activities although they are not as effective. If the wound was caused by shoe pressure on a prominent hammer toe or bunion then elimination of the problem shoe is paramount. Special toe pads or shoe modifications may help as well. These wounds usually require periodic sharp debridement to remove dead or devitalized skin and bacteria by your podiatrist. The good news is that this is usually not very painful due to the lack of pain sensations from the neuropathy.
If conservative wound care fails to heal the wound or significant infection develops then sometimes surgical intervention may be needed. We perform an in-office procedure called a tenotomy for wounds on the tips of contracted hammertoes. It involves releasing one or more of the tendons that are causing the toe contracture and helps to straighten the toe. These wounds usually heal rapidly after this with minimal recovery or pain. Other surgical procedures might include an Achilles tendon lengthening and/or removal of a bony prominence depending on the location and nature of the wound. Once healed, special extra depth shoes and cushioned shoe liners made of soft foam material can help prevent wounds from returning.
Venous Stasis Ulcers: Reducing the swelling in the limb is critical to heal these wounds. This usually entails some type of compression wrap/dressing along with regular elevation of the leg above the level of the heart. This allows gravity to help push the excess fluid and edema from the limb and speeds up the healing process. Regular dressing changes and occasional wound debridements are typically needed. Once healed, daily use of medical grade compression socks to keep the swelling reduced will hopefully prevent the wound from returning.
Ischemic Ulcers: Immediate smoking cessation is critical. Specialized testing to determine the nature of vessel blockage will be ordered. Restoration of blood flow to the affected limb is also crucial. This will be done in consultation with a vascular surgeon that specializes in this. Vascular surgeons can sometimes perform an angioplasty to open the blocked arteries with stents or other means and at times may need to perform an open bypass to re-route blood around the blocked vessel. Once blood flow has been restored then the wound will hopefully have enough circulation to start the healing process. Your podiatrist will regularly monitor the wound to assess healing and the appropriate wound care regimen. In some circumstances hyperbaric oxygen treatments may also be needed.
Sometimes the exact cause of an ulcer may be difficult to determine and might be a mixture of several different conditions. At times, biopsy of the ulcer may help to diagnose the condition. X-rays or even an MRI may be needed to rule out deeper bone infection.