Wounds come in all shapes and sizes – from minor punctures to those that require large skin grafts. Yet what they all have in common is their common goal, which is to heal quickly and efficiently.
However, for many reasons, this does not always happen. Chronic wounds, for example, do not progress through the healing process in a timely manner. They may remain in the inflammation phase for prolonged periods of time, which exacerbates cell damage and disrupts the healing process.
Chronic wounds, with their inability to heal quickly, have become a major challenge to healthcare systems worldwide. It is estimated that in the US alone, 2.4 – 4.5 million people have some sort of chronic wound. Moreover, chronic wounds, such a leg-ulcers recur in 60 – 70% of patients.
What all of this often leads to is the loss of function, decreased quality of life, and increased rates of comorbidity. However, with the right treatment, chronic wounds can heal.
It Is A Specialty
Because chronic wounds do not proceed through the normal or expected, phases of healing, the treatment of them differs from the treatment of typical wounds. One differentiating factor is that chronic wounds often do not respond to typical wound healing signals. For example, fibroblasts exhibit a diminished proliferative capacity which is directly correlated with the failure of a wound to heal.
Chronic wounds also exhibit oxidative stress that leads to cellular damage as well as abnormal metabolic changes in diabetic patients. Further, protease levels exceed that of their respective inhibitors, which leads to the degradation of growth factors and their receptors. The result is that the wound does not move into the proliferative phase of healing, and it also attracts more inflammatory cells, which further disrupts healing.
In order to stop the progression of inflammation, cellular damage and disrupted healing, and specialized approach is required. This often involves using advanced therapies, including growth factors, extracellular matrices, engineered skin, and negative pressure wound therapy.
It is also important to correctly assess the patient to determine what co-existing conditions may inhibit wound healing. Some of these include diabetes, obesity, chronic kidney disease, peripheral artery disease. Further, many metabolic factors must be assessed to determine their impact on wound healing. These include medications such as steroids and antibiotics, as well as laboratory parameters such as glucose, hemoglobin A1c, creatinine, complete blood count, albumin, erythrocyte sedimentation rate, C-reactive protein, etc. Lastly, patient nutrition must be considered.
The wound must also be correctly assessed to determine the etiology, wound depth, location, presence of infection, neurological impairment, as well as any structural deformities that may complicate wound healing.
Many Steps Are Involved
As chronic wound treatment requires a specialized approach, many steps are involved. These can be broken down into the following four steps, or phases: hemostasis, inflammation, proliferation, and remodeling phases.
Hemostasis. Hemostasis occurs immediately after injury and is characterized by vasoconstriction and blood clotting. As blood clotting prevents blood loss, platelets secrete growth factors and cytokines attract fibroblasts, endothelial cells, and immune cells to initiate the healing process.
Inflammation. The inflammation phase lasts up to 7 days and involves phagocytic cells, such as neutrophils and macrophages. Neutrophils release reactive oxygen species (ROS) and help to prevent bacterial contamination and cleanse the wound of cellular debris. Macrophages act to remove bacteria and nonviable tissue by phagocytosis. They also release various growth factors and cytokines which help to repair the damaged blood vessels.
Proliferation. The proliferation phase is primarily characterized by tissue granulation, the formation of new blood vessels (angiogenesis), and epithelialization.
Remodeling. Once the wound has closed the remodeling phase begins where the provisional matrix is remodeled into organized collagen bundles. This phase may last 1–2 years or longer.
As healing progresses through these phases, treatment may include medical management, such as draining abscesses, use of hyperbaric oxygen, and revascularization. Wound care may also include debridement, wound bed preparation, offloading, and the use of therapeutic agents. In extreme cases, treatment may require surgery.
A Comprehensive Approach Is Best
As the etiology and challenges of chronic wounds become well understood, it becomes clear that a comprehensive approach is best. Through understanding the underlying molecular and physiologic complications of nonhealing wounds, the necessity to modify these wounds toward the characteristics of an acute healing wound also becomes evident.
A primary factor is to restore the proper balance of cytokines, growth factors, proteases, and metabolically competent cells. The care for chronic wounds also relies upon removal of the etiologic causes, in addition to addressing the underlying systemic and metabolic challenges such as infection or peripheral arterial disease.
Treatment of chronic wounds also relies on accurate wound assessment. This helps the physician account for factors that may be contributing to the development and recurrence of the wounds. Management of these associated complications or etiologic factors plays a key role in encouraging the proper environment in which tissue repair can take place.
As each wound has its own underlying etiopathogenesis this must be addressed upon initial evaluation. Part of this evaluation must include ruling out the presence of malignancy in the wound either secondarily due to malignant degeneration or as a primary factor.
As our population ages, and the percentage of seniors rises, so does the number of chronic wounds. Because they are not like typical wounds and do not follow the expected healing process, the treatment of chronic wounds is a specialty that involves many steps, as well as a comprehensive approach that accounts for and treats the many complicating factors of chronic wound healing.