Wound Healing Disorders and Impaired Wound Healing – Understanding Pathophysiology, Wounds, and Impaired Wound Healing

A wound healing disorder is defined as a chronic wound that has not healed within 12 weeks. Normally, a wound heals within 2 weeks. Wound healing disorders are also among the most common complications of surgery. In fact, one-fifth of all surgical patients experience wound healing disorders.

A wound healing disorder can be triggered by various deficiency states and underlying medical conditions. Generally, a distinction can be made between local factors (in the immediate vicinity of the wound) and systemic factors (affecting the entire body). However, a combination of local and systemic factors is often present.

What are the systemic causes of wounds and wound healing disorders?

Systemic factors include, among others:

• Underweight due to malnutrition or poor nutrition
• Overweight 
• Diabetes
• Advanced age
• Smoking
• Circulatory disorders (arterial and venous diseases)
• Immune deficiency

Why does malnutrition lead to impaired wound healing?

Although we live in abundance and hunger is not a problem in developed countries, malnutrition (nutritional deficiency or poor diet) is a cause of impaired wound healing. An improper diet leads to a deficiency in nutrients such as proteins, carbohydrates, fats, minerals, trace elements, and vitamins. However, these are necessary for the natural wound healing process, as wound tissue is particularly metabolically active and consequently consumes a large amount of these substances.

However, overeating can also be a cause of impaired wound healing. In particular, an unhealthy diet high in fat and sugar is a contributing factor here.

Is the risk of impaired wound healing increased in older adults?

Advanced age is also a risk factor for poorly healing wounds and can be described as a systemic factor. Generally speaking, the older a person is, the slower the wound healing process tends to be. This is related to a slowing of all metabolic processes and a deterioration in tissue perfusion.

However, medication use or chronic cardiovascular or cancer-related conditions can also lead to impaired wound healing. This must be taken into account prior to surgical procedures.

How does smoking affect wound healing? 

Smokers are more likely to have chronic wounds, particularly on the feet and, more specifically, in the toe area. Wounds following surgical procedures also heal significantly more slowly in smokers. Studies show that up to 50 percent of all smokers suffer from wound healing disorders after surgery. Among nonsmokers, the figure is only about 10 percent. This is likely due to the fact that smokers have poorer blood circulation. Additionally, toxins from smoking have a detrimental effect on wound healing and lead to insufficient oxygen supply to the tissues.

Other causes of oxygen deprivation include diabetes, vascular diseases of the arteries (peripheral arterial disease) and veins (varicose veins and thrombosis), as well as anemia.

What role do medications and a weakened immune system play?

Another important cause of impaired wound healing is a weakened immune system. A weakened immune system—for example, in cases of cancer or chronic infectious diseases such as AIDS—impairs the healing process. The same applies to various medications such as immunosuppressants, anticoagulants, and cytostatics, which are frequently used in cancer treatment.

What factors in the wound environment impair wound healing?

Changes in the wound environment—so-called local factors—can also significantly impair wound healing. In particular, large, deep, dry, or dirty wounds, as well as crushed wounds, are prone to impaired healing. Pus or bruising can further delay the healing process, as can bacteria in the wound area.

Generally speaking, small and superficial wounds heal better than large and deep wounds. In general, smooth lacerations heal more favorably than, for example, bite wounds. Improper wound care following an injury can also lead to wound healing complications. The wound dressing should protect the wound from drying out and allow for a good supply of oxygen.

If the wound needs to be sutured, the stitches should not be too tight. If the sutures are removed too early, the wound may reopen.

The primary symptom of a wound healing disorder is a wound that does not heal. The clinical presentation may vary depending on the type of disorder. The wound may swell, become red, and be painful. If the edges of the wound separate or the wound bursts open, this is referred to as wound dehiscence. This phenomenon occurs primarily after surgery. The wound may be surrounded by blood (wound hematoma = bruise) or contain dead tissue (necrosis). Such a necrotic wound appears bluish-purple or black. Some wounds also ooze fluid or are accompanied by itching and fever.

What should be considered during scar formation?

Another wound-healing disorder is a keloid scar, which refers to excessive scar formation. In this condition, there is an increased production of so-called fibroblasts, which are a major component of connective tissue. This results in a benign tumor that protrudes above the skin’s surface. Normally, a keloid is purely a cosmetic issue, but occasionally it can be accompanied by itching or sensitivity to touch.

After a detailed discussion (medical history), the wound or scar is examined and palpated. The doctor also checks whether blood flow, sensation, or motor function is impaired and which structures are affected. The condition of the wound is also assessed, particularly to determine whether there is any dead tissue or pus present. For smaller wounds, it is usually sufficient to examine them, clean them carefully, and apply a dressing.

Larger wounds and significant healing complications generally require further testing. For example, a blood test can provide information about the functioning of the immune system and indicate whether an infection is present. Deeper and internal wounds can only be assessed using imaging techniques such as X-rays, computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound. If an infection of the wound is suspected, a wound swab is taken so that the exact pathogen can be identified and, if necessary, an effective antibiotic can be prescribed.

Treatment for impaired wound healing can be divided into local and systemic therapy. The most important factor for the success of local therapy is wound hygiene. The wound must be kept clean, but must not be overly irritated by disinfectants under any circumstances. For cleaning, saline rinses or wound soaks with tap water at body temperature are used. Dead tissue, foreign bodies, or debris are surgically removed.

Chronic wounds should, if possible, be managed regularly by an experienced wound care specialist. This specialist selects the appropriate wound dressing, which protects the wound while also maintaining a moist wound bed to promote healing. If there is a significant wound infection, treatment with antibiotics may be appropriate. To determine in advance whether the wound is resistant to certain antibiotics, a wound swab is usually taken before starting antibiotic therapy.

Antibiotics are usually administered as an infusion or tablet for systemic treatment. However, to promote the healing process, it is essential to treat the underlying cause of the wound healing disorder. Despite intensive treatment, complete healing is not always possible, so amputation may be necessary as a last resort.

If the cause of the wound healing disorder can be eliminated, the prognosis is generally good. The rule of thumb is: The sooner the wound receives optimal care, the better the chances of healing. However, people with advanced chronic diseases that impair wound healing, in particular, suffer from poorly healing wounds throughout their lives. Even very minor injuries must be treated by a specialist in these cases to prevent further sites of inflammation from developing.

What is a wound healing disorder?

A wound healing disorder is defined as a condition in which wound healing is delayed or impaired. Wound healing disorders affect both acute and chronic wounds. In such cases, an open wound either fails to form sufficient granulation tissue or develops necrosis.

What are the causes of wound healing disorders?

Causes of wound healing disorders include local factors such as foreign bodies, pathogens, or a wound infection. Systemic factors such as underlying conditions like diabetes, malnutrition, or a weakened immune system also act as risk factors. Circulatory disorders or chronic venous insufficiency can also contribute to poor wound healing.

What role do blood flow and blood vessels play?

Adequate blood flow is essential for supplying the wound with oxygen and nutrients. Peripheral arterial disease (PAD) or venous insufficiency leads to circulatory disorders, which impair wound healing. In vascular surgery, appropriate measures are taken to stabilize the blood vessels and promote healing.

How are wound healing disorders treated?

The treatment of wound healing disorders depends on the underlying causes and risk factors. Professional wound care using appropriate wound dressings, as well as modern wound treatments such as vacuum therapy, may be employed. If a wound infection is suspected, targeted therapy is administered, including surgery if necessary. A structured approach to diagnosis and treatment is crucial.

Can wound healing disorders be prevented?

Wound healing disorders can be prevented through optimal wound care and management of underlying medical conditions. Good blood sugar control in diabetes mellitus, adequate nutrition, and avoiding infection reduce the risk. Early detection of problems helps prevent complications and allows the wound to heal stably into a scar.