A stasis ulcer is an open wound on the lower leg caused by poor blood flow in the veins, most often appearing near the inner ankle bone. It’s the most common type of leg ulcer, and despite treatment, healing typically takes 6 to 12 months. These wounds develop when valves inside leg veins stop working properly, allowing blood to pool instead of flowing back up toward the heart. That sustained pressure eventually damages the skin enough to break it open.
How Venous Pressure Causes Skin Breakdown
Veins in your legs contain one-way valves that push blood upward against gravity. When those valves weaken or fail, blood flows backward and collects in the lower legs. This is called chronic venous insufficiency. Over time, the persistent pressure forces fluid and proteins out of the veins and into surrounding tissue, triggering inflammation that slowly degrades the skin.
The damage doesn’t happen overnight. Before an ulcer forms, you’ll typically see a progression of warning signs. Early changes include small spider veins and visible bluish veins just under the skin. As the condition advances, the skin around the ankles develops a brownish-orange discoloration from iron deposits left by leaking red blood cells. The skin may become thick, hard, and leathery, a condition called lipodermatosclerosis. Itchy, flaky patches of stasis dermatitis often appear. Eventually, this weakened skin gives way, and an ulcer opens.
Where They Appear and What They Look Like
Stasis ulcers have a characteristic location and appearance that sets them apart from other types of wounds. They form in the “gaiter area” of the leg, the zone between the calf and the ankle. The most common spot is around the inner ankle bone. When the small vein running along the back of the calf is involved, ulcers can also develop near the outer ankle bone.
The ulcers themselves are typically shallow with irregular but well-defined edges. The wound bed often contains a yellowish fibrous material rather than deep exposed tissue. The skin surrounding the ulcer is usually discolored, swollen, and inflamed. Unlike arterial ulcers, which tend to be small, deep, and punched-out in appearance, stasis ulcers are broader and more superficial.
Risk Factors
Anything that damages vein valves or increases pressure in the leg veins raises your risk. A history of deep vein thrombosis (blood clots) is one of the strongest contributors, because clots can permanently scar the vein walls and destroy valve function. Other significant risk factors include:
- Obesity: Higher body weight increases pressure on leg veins. Research shows that elderly male patients with high BMI and existing vein problems face the greatest risk of progressing to ulcers.
- Prolonged standing: Occupations that keep you on your feet for hours, such as teaching, law enforcement, or bus conducting, accelerate vein damage.
- Age and gender: Risk climbs with age, and women face additional risk from pregnancy and hormonal changes.
- Family history: Chronic venous insufficiency has a genetic component.
- Smoking: Particularly in men, smoking increases the risk of blood clots that can trigger the underlying vein disease.
- Other conditions: Diabetes, high blood pressure, and thyroid disorders have a variable but notable association with chronic venous insufficiency.
How Stasis Ulcers Are Diagnosed
Diagnosis is primarily visual and clinical. The combination of a shallow wound near the inner ankle, surrounded by skin discoloration, swelling, and signs of chronic vein disease, is usually enough for a healthcare provider to identify a stasis ulcer without a biopsy.
One important test checks whether arterial disease is also present, since about 20% of people with venous ulcers have reduced arterial blood flow at the same time. This is measured by comparing blood pressure at the ankle to blood pressure in the arm. A normal ratio falls between 1.0 and 1.3. Values below that indicate some degree of arterial disease, which changes the treatment approach. Values above 1.3 can signal calcified blood vessels and need urgent evaluation.
An ultrasound of the leg veins is often performed to map out which veins are damaged and whether blood clots are present. The scan can detect faulty valves by measuring how long blood flows backward through them. Deeper veins that are harder to see on ultrasound may require CT or MRI imaging.
Treatment: Compression Is the Foundation
Compression therapy is the cornerstone of stasis ulcer treatment. Firm bandaging or specialized stockings squeeze the leg in a graduated pattern, tightest at the ankle and gradually loosening toward the knee. This counteracts the pooling of blood and helps push fluid back into circulation. For healing venous ulcers, a sustained pressure of 30 to 40 mmHg at the ankle is recommended. During walking, pressures exceeding 50 to 60 mmHg further improve the vein pumping mechanism.
If you also have arterial disease (identified by that ankle-to-arm blood pressure ratio), compression is modified. Stiffer bandages applied at lower pressures, generally under 40 mmHg, can still improve both arterial and venous blood flow without cutting off circulation. Full compression is not safe when arterial blood supply is significantly reduced.
Wound Care and Dressings
Keeping the ulcer in a moist environment is essential for healing. Dry wounds heal more slowly because skin cells need moisture to migrate across the wound bed. Modern dressings are designed to maintain this moisture balance while absorbing excess fluid that the wound produces.
Before dressings can work effectively, dead tissue often needs to be removed from the wound, a process called debridement. This can happen several ways. Surgical debridement uses instruments to physically remove dead tissue and essentially converts a chronic wound into a fresh one that the body can heal more readily. Autolytic debridement is gentler, relying on moisture-retaining dressings that allow the body’s own enzymes to gradually dissolve dead tissue. In some cases, specially raised fly larvae are applied to the wound. They secrete enzymes that selectively break down only dead tissue while leaving healthy tissue intact.
The skin surrounding the ulcer also needs protection. Barrier creams or petroleum jelly can shield healthy skin from irritation caused by wound drainage. Zinc oxide paste preparations provide both skin protection and anti-inflammatory effects. When infection is a concern, dressings containing iodine or silver-based compounds help control bacteria on the wound surface. Simple saline-soaked dressings, changed frequently, can also keep the wound clean and moist.
Treating the Underlying Vein Problem
Compression and wound care treat the ulcer itself, but addressing the damaged veins reduces the chance of recurrence. Several minimally invasive procedures can shut down or remove veins that are no longer functioning properly.
Endovenous thermal ablation targets larger diseased veins using laser or radiofrequency energy to generate heat that seals the vein closed. The vein stays in place but stops carrying blood, so there’s minimal bleeding or bruising. Sclerotherapy works for smaller veins by injecting a solution that causes the vein to collapse. For varicose veins close to the skin surface, a procedure called ambulatory phlebectomy removes them through tiny incisions. Another option specifically targets the perforating veins above the ankle, using a small camera and clips to block off damaged veins. This procedure helps ulcers heal and helps prevent them from returning.
Healing Timeline and Recurrence
Even with proper treatment, stasis ulcers are slow to heal. The average healing time ranges from 6 to 12 months, and roughly one in five ulcers hasn’t healed after two full years of treatment. If a wound shows no progress toward healing within the first one to three months, or remains open after 12 months of optimal care, it’s considered treatment-resistant and may need a different approach.
Perhaps the most frustrating aspect of stasis ulcers is how often they come back. The relapse rate within five years of healing reaches nearly 70%. This high recurrence rate is why treating the underlying vein problem, not just the wound, matters so much. Lifelong use of compression stockings, regular leg elevation, weight management, and physical activity all help reduce the odds of another ulcer forming.
Complications of Nonhealing Ulcers
Ulcers that remain open for long periods carry serious risks. Cellulitis, a bacterial skin infection that spreads into deeper tissue layers, is one of the most common complications. If bacteria reach the bloodstream, sepsis can develop. Bone infection, or osteomyelitis, can occur when an ulcer sits close to bone and may ultimately require amputation if it can’t be controlled. In rare cases, chronic wounds that persist for years can develop squamous cell skin cancer within the ulcer itself.