A non-pressure ulcer is a chronic wound that develops from causes other than sustained pressure on the skin. While pressure ulcers (bedsores) form when tissue is compressed against a bone or surface for too long, non-pressure ulcers result from problems like poor blood circulation, nerve damage, or prolonged moisture exposure. They most commonly appear on the lower legs and feet, and they account for billions of dollars in healthcare costs annually in the United States alone.
These wounds get stuck in the early stage of healing, often lasting weeks, months, or even years without closing. The three most common types are venous ulcers, arterial ulcers, and diabetic (neuropathic) ulcers, each with distinct causes, appearances, and locations on the body.
How Non-Pressure Ulcers Differ From Pressure Injuries
Pressure injuries form over bony prominences like the tailbone, hips, and heels, or under medical devices like oxygen tubing or casts. The damage comes from sustained force compressing the skin and tissue underneath. Non-pressure ulcers, by contrast, develop because something has gone wrong with circulation, nerve function, or the skin’s protective barrier. The location of the wound is one of the fastest ways to tell them apart: a sore directly over a bony point that bears weight or contact is likely pressure-related, while a wound on the inner ankle, shin, or sole of the foot points toward a vascular or neuropathic cause.
There’s also a category of skin breakdown caused by prolonged moisture exposure, sometimes called incontinence-associated dermatitis. These lesions appear on the buttocks, groin, and perineum, and they often feel like burning or itching rather than deep pain. The skin tends to look red and weepy rather than forming a distinct crater. Small satellite spots or blisters around the main area can signal a secondary yeast infection, which is common in more severe cases. These moisture-related wounds are sometimes mistaken for pressure injuries because they occur in similar areas, but their cause and treatment differ significantly.
Venous Ulcers
Venous ulcers are the most common type of non-pressure ulcer on the legs. They develop when the veins in your lower legs can’t push blood back up to the heart efficiently. Valves inside the veins weaken or fail, blood pools in the lower leg, and the resulting pressure forces fluid into surrounding tissue. Over time, this swelling damages the skin and underlying tissue enough to create an open wound.
These ulcers typically appear just above the ankle, in the area sometimes called the “gaiter zone” (the part of the leg a sock or gaiter would cover). They tend to be shallow with a red wound bed, sometimes topped with yellow tissue. The borders are irregular and uneven rather than round. Swelling in the surrounding leg is common, and the skin nearby may look discolored or feel thick and leathery. If the wound becomes infected, you may notice a foul smell or drainage that looks like pus.
Pooled prevalence of venous leg ulcers sits at roughly 0.3% of the general population, but among people already receiving wound care, that figure jumps to nearly 0.7%. In the U.S., venous ulcers contribute to an estimated $32 billion in annual healthcare spending. The standard treatment centers on compression therapy (specialized wraps or stockings that squeeze the leg) combined with elevating the limb. Compression reverses the fluid buildup and helps blood flow back toward the heart. Without consistent compression, these ulcers frequently reopen even after healing.
Arterial Ulcers
Arterial ulcers form when not enough oxygen-rich blood reaches the lower legs and feet. The underlying problem is narrowed or blocked arteries, a condition called peripheral artery disease. Without adequate blood flow, the tissue can’t repair itself from even minor injuries, and wounds develop that refuse to heal.
These ulcers look quite different from venous ones. They tend to have a “punched out” appearance: round or oval, with sharp, well-defined borders, as if someone used a hole punch on the skin. They commonly appear on the tops of the feet, toes, or lower shins rather than around the ankle. Arterial ulcers are often painful, especially at night. The surrounding skin may feel cool to the touch, look pale or shiny, and have little or no hair growth, all signs of reduced blood flow.
A simple, painless test called the ankle-brachial index helps identify arterial disease. It compares blood pressure at the ankle to blood pressure in the arm. A normal reading falls between 1.0 and 1.3. A result of 0.9 or lower indicates peripheral artery disease, with readings below 0.4 signaling severe disease. Treatment focuses on restoring blood flow, sometimes through vascular surgery, alongside lifestyle changes like quitting smoking and managing cholesterol. Compression therapy, which is essential for venous ulcers, can actually be harmful for arterial ulcers because it further restricts already limited blood flow. This is why getting the right diagnosis matters so much.
Diabetic and Neuropathic Ulcers
Neuropathy, or nerve damage, drives ulcer development in roughly 60% of people with diabetes. The process starts with loss of sensation in the feet. When you can’t feel pain, pressure, vibration, or temperature changes, small injuries go completely unnoticed. A blister from a tight shoe, a cut from stepping on something sharp, or simply the repetitive stress of walking can cause damage that you never register.
The typical sequence begins with callus formation at pressure points on the foot. Neuropathy changes how the foot muscles work, leading to deformities like clawed toes and altered gait patterns. These changes redistribute weight unevenly, creating new high-pressure zones. The callus builds up, bleeding develops underneath it, and eventually the tissue erodes into an open ulcer. Because the person can’t feel it happening, the wound is often well-established before it’s discovered.
Diabetic foot ulcers most commonly develop on the sole of the foot, particularly under the ball of the foot near the base of the big toe or little toe, and on the heel. These are the areas bearing the most mechanical pressure during walking. The combination of nerve damage, poor circulation (which is also common in diabetes), and immune system changes makes these wounds especially dangerous. Without proper treatment, infection can spread to the bone, and in severe cases, amputation becomes necessary.
Grading Severity
Clinicians often use the Wagner classification to describe how advanced a diabetic foot ulcer has become. At Grade 0, the skin is still intact but foot deformities put the person at high risk. Grade 1 is a shallow, surface-level ulcer. Grade 2 means the wound extends deeper through the full thickness of skin. Grade 3 involves deep infection reaching the bone. Grades 4 and 5 describe partial and extensive tissue death, respectively. Most treatment efforts aim to catch ulcers at the earliest grades, when the wound can still be managed with offloading (taking pressure off the foot), proper wound care, and blood sugar control.
Why These Wounds Become Chronic
All three ulcer types share a core problem: the body’s normal healing process gets disrupted. In a healthy wound, inflammation kicks off a repair sequence that progresses through tissue rebuilding and eventually closure. Non-pressure ulcers get stuck in the inflammatory phase. The underlying cause, whether it’s pooling blood, oxygen-starved tissue, or nerve damage, keeps interfering with each step of repair.
Diseases that weaken the immune system compound the problem. Diabetes impairs white blood cell function. Vascular disease limits the delivery of oxygen and infection-fighting cells to the wound site. Even antibiotics have trouble reaching tissue that doesn’t have good blood flow. This is why treating the wound itself is never enough. The underlying circulation problem, nerve damage, or metabolic issue has to be addressed at the same time, or the ulcer will either stall or reopen after it closes.
Telling the Types Apart
- Location: Venous ulcers sit above the ankle on the inner leg. Arterial ulcers favor the toes, tops of feet, and shins. Diabetic ulcers form on the sole of the foot, especially at weight-bearing points.
- Appearance: Venous ulcers are shallow with irregular edges and a red or yellow base. Arterial ulcers look punched out with clean, defined borders. Diabetic ulcers often start beneath calluses and may have a deep, crater-like shape.
- Pain: Venous ulcers cause a dull ache that improves with elevation. Arterial ulcers produce sharp pain that worsens at night or when the legs are raised. Diabetic ulcers are often painless due to nerve damage, which is part of what makes them so dangerous.
- Surrounding skin: Venous ulcers are surrounded by swollen, discolored skin. Arterial ulcers sit in skin that’s pale, cool, and hairless. Diabetic ulcers may be surrounded by thick callus with warm, dry skin.
Some people, particularly older adults with diabetes and vascular disease, develop mixed ulcers where more than one cause is at play. These are harder to treat because the approaches can conflict. Compression helps venous disease but harms arterial flow, so clinicians need to assess circulation carefully before choosing a treatment plan.