chronic wounds

Chronic Wounds – An Overview of Causes, Types, and Treatment

What Are Chronic Wounds?

Chronic wounds, sometimes called hard-to-heal or difficult-to-heal wounds, impact the quality of life for almost 2.5% of the US population. A wound that has stopped progressing toward healing for at least 4 weeks qualifies as a chronic wound. Where acute wounds typically progress toward healing in a predictable manner, chronic wounds get stuck in the inflammatory phase of wound healing.

The elderly are at increased risk of developing chronic wounds; as the population ages the number of patients with chronic wounds (currently approximately 6.5 million) is likely to increase. Not only do chronic wounds cause pain, but they can also be socially limiting and associated with anxiety, depression, and functional limitations. They strain the healthcare system as a whole, with projected wound care market costs of $18.7 billion by 2027.

What causes chronic wounds?

Many factors increase the risk of developing chronic wounds. Patient variables that increase the risk of failure to heal include:

  • Diabetes
  • Venous disease and edema
  • Arterial disease
  • Limited mobility and pressure
  • Obesity
  • Advanced age
  • Poor nutrition
  • Smoking

In addition to these patient variables, compromised social determinants of health (SDOH) and poor access to health care also contribute to risk.

  • Wound healing may stall following an infection or bacterial over-colonization.
  • Repetitive trauma to the area also can cause chronic wounds.

Types of Chronic Wounds

1. Diabetic Wounds or Diabetic Foot Ulcers

diabetic foot ulcer

Diabetes is a major risk factor for delayed wound healing based on chronic underlying microvascular changes, neuropathy, the tendency for repetitive injury, and a tendency toward infection. These wounds may appear small on the surface but extend to a large area underneath. Deep infections may occur in the bone or deep soft tissue and are a significant risk to both the healing process and the patient’s overall well-being.

2. Arterial Ulcers

arterial ulcer

Ulcers that occur due to poor blood supply are considered arterial or ischemic ulcers. These wounds typically heal if the arterial compromise can be corrected. If the blood flow cannot be improved, these wounds may progress to amputation or life-threatening infection.

3. Venous Ulcers

venous ulcers

Also called stasis ulcers, these wounds form due to venous system dysfunction. This causes venous hypertension, which leads to compromised venous return, edema, and increased risk of ulceration. If the stasis can be improved, usually by compression and elevation, these wounds usually go on to heal.

4. Pressure Injuries

Bed sores, also called pressure wounds, are caused by excess pressure on the skin/soft tissue overlying bony prominences. The external pressure exceeds capillary opening pressure, resulting in tissue loss. If the site is effectively offloaded and the wound remains clean, these chronic wounds can be transitioned into healing wounds. If the site cannot be offloaded, these wounds may persist long-term.

5. Radiation Injuries​

Radiation therapy used for cancer treatment may cause tissue damage and scarring. This damage tends to increase over time and may result in wound formation 10-20 years later. These wounds are difficult to treat given the tissue bed fibrosis and decreased capillary density associated with this.

6. Infectious wounds

These wounds may arise from local infection, such as an abscess or cellulitis. They may also result from infection in a previous wound or surgical site, causing exacerbation and worsening of the site. The primary treatment for an infected wound is to resolve the infection. Any purulence must be drained. Necrotic tissue – a nidus for bacteria – must be removed, as well as any foreign bodies that may be present. Antimicrobials appropriate to the clinical situation are also indicated.

7. Surgical wounds

While most surgical sites heal as expected, sometimes infections may develop and cause delayed healing and possible dehiscence. Other surgical wounds may be deliberately left open (to close by secondary intention) and require wound care until closed. These wounds can be large and deep and often require several different types of dressing management as the healing progresses.

How to Heal a Chronic Wound

Chronic wounds heal when barriers to healing are removed. When approaching a wound that has stalled, one must consider factors affecting wound healing overall, not just the specific wound treatment.

1. Nutrition

Good nutrition is critical to support the healing process. Inadequate protein, vitamins, minerals, and insufficient calories all restrict the body’s ability to synthesize the materials needed for healing. Patients with any type of malnutrition are at high risk for the development of chronic wounds; their nutritional status must be optimized.

2. Infection

Chronic underlying infections, such as osteomyelitis, can cause delayed healing. This is often seen in chronic diabetic foot wounds. It is important to consider underlying infection in wounds that fail to progress.

3. Tissue health

The presence of necrotic tissue impedes healing. When a wound bed is covered with necrotic tissue, the fibroblasts and other cell types must migrate around or under the nonviable tissue mass, causing significant delays in the process. Additionally, necrotic tissue is a haven for bacteria and puts the patient at increased risk of infection.

4. Biofilm

Most surfaces develop biofilm over time. Biofilm is a collection of bacteria within a layer of extracellular polymeric substances (EPSs). This layer of EPSs strongly inhibits healing. A chronic wound bed is often covered with biofilm; removal of this layer is often necessary to restart the healing process.

5. Failure to remove causative factors

Many wounds have factors that either cause or contribute to the formation of the wound. Diabetic patients who do not have appropriate offloading and protective footwear may continue to traumatize their feet and have pressure points from shoes. Patients with chronic pressure wounds must have the area offloaded for healing. Patients with venous stasis ulcers must have appropriate stasis management (compression and elevation of the legs) for their wounds to heal and remain closed.

6. Wound care

After addressing the above factors, some wounds remain chronic. Advanced wound care products such as growth factors, amnionic membranes, skin substitutes, collagen products, and negative pressure devices may be beneficial in these situations to restart healing. Adjunctive treatments such as electronic wound stimulation (e-stim), diathermy, and non-contact ultrasound may help to heal the wound faster. Hyperbaric oxygen may also be useful in appropriate clinical situations.


Chronic wounds affect millions of people, causing significant suffering and depleting limited healthcare resources. There are a variety of types of chronic wounds. Treatment of these wounds involves not only caring for the wound but addressing the underlying factors that contribute to the wound’s chronicity.


1. What is the fastest way to heal a chronic wound?

Wounds heal fastest when they are kept clean and free of nonviable tissue. Additionally, wounds managed with appropriate dressings heal more quickly than those treated with unsuitable dressings. Finally, wounds heal much more quickly in patients whose lower extremity edema is well controlled with compression and elevation.

2. Which vitamin deficiencies delay wound healing?

Vitamin A is important for wound healing; deficiencies slow the healing process. Other vitamins important for healing include Vitamin C, D, and the mineral Zinc.

3. Which vitamins help the body heal wounds?

Vitamin C, Vitamin A, and Zinc are very important for wound healing. Additionally, proteins, carbohydrates, arginine, glutamine, polyunsaturated fatty acids, vitamin E, magnesium, copper, and iron play a significant role in wound healing.

4. When should you stop covering a wound?

Most wounds require some sort of dressing. Any open wound with drainage needs to be covered and some type of primary dressing product applied to the wound bed. In short, open wounds require some type of treatment to the wound bed itself, which requires a dressing. Scabs and dry areas do not typically require coverage. These do well when left open to air with a surface treatment such as skin prep.

Resources and References


  • Assessing the impact of coronavirus on wound care patients and practice. William J Ennis. Published on 2020 March 23rd.


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Author: Janet S. Mackenzie, MD, ABPS, CWSP, AAGP

Janet S Mackenzie MD, ABPS, CWSP, AAGP is the Chief Medical Officer at Vohra Wound Physicians. She has been with the company since 2013 and has almost 30 years of wound care experience as both a plastic surgeon and a wound care specialist. After obtaining a Master’s degree in Education, she obtained her Medical Degree from the University of Pennsylvania Perelman School of Medicine. She trained in general surgery at Dartmouth Hitchcock Medical Center and plastic surgery at McGill University. She is board certified by the American Board of Plastic Surgery, the American Board of Wound Management, and the American Board of General Medicine, and is a Certified Wound Specialist Physician (CWSP).

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