What is the wound healing process for open wounds? How many stages are there in the healing process?

The healing process of open wounds goes through 3 stages, from hemostasis to skin regeneration. This is a natural process of the skin involving a series of complex biological reactions, aimed at restoring the skin to its intact state prior to injury.

Basically, the wound healing process of open wounds occurs similarly. However, the time and quality of scar healing may vary among individuals depending on many factors such as wound care, severity of injury, age, etc.

1. What is the wound healing process?

Skin accounts for about 15% of the body’s weight – an organ that protects internal parts of the body from damage and direct external factors. In an adult, the total skin surface area ranges from 4m² to 6m².

As the “front line,” skin is also the most vulnerable organ. The body activates protective mechanisms when skin encounters injuries such as tears, abrasions, surgical wounds, punctures, or chronic wounds.

Medically, the open wound healing process is the interaction of cells to regenerate new epithelium and skin tissue, helping the wound to recover and re-establish the skin’s barrier function.

Thus, wound healing is also called the scarring process. Scars are the result of wound healing and are classified into two main types:

• Normal scars
• Abnormal (pathological) scars, including:

• Keloid scars
• Hypertrophic scars
• Atrophic scars
• Stretch marks

Typically, acute wounds heal within 8 weeks. Chronic wounds take longer and may not restore full function or integrity compared to the original state.

2. Main stages of open wound healing

The wound healing process passes through 3 main stages in order:

INFLAMMATION – PROLIFERATION – EPITHELIALIZATION

Each stage is important for wound healing. Understanding each stage helps in better wound care, faster healing, and reduces the risk of infection or poor scarring.

• Stage 1: Inflammation

“Inflammation” is the first stage of the open wound healing process, occurring immediately after injury with the purpose of stopping bleeding, cleaning the wound, and creating a barrier to prevent bacterial invasion through the open wound to avoid infection.

This stage is very important because the immune system tries to protect the damaged skin and helps the body self-heal.

• Duration: from a few hours to 4 days (average about 48 hours).
• Cells involved: platelets, neutrophils, macrophages, etc.
• Signs at the wound: swelling, heat, redness, pain, fever.
• Tasks: stop bleeding, clean the wound.
• Mechanism:

When a wound appears, endothelial cells and blood vessels are damaged, causing bleeding. Blood contact with collagen leads to clotting. The clot stops bleeding and seals the wound; it also produces substances that attract other important cells to the wound area to participate in healing:

– Platelets: release inflammatory mediators to trigger inflammation, activating fibroblasts and endothelial cells.

– Macrophages: clean the wound and prepare for epithelial cell proliferation by eliminating necrotic tissue, bacteria, and foreign materials.

• Stage 2: Proliferation / Granulation

The next stage of the healing process is “proliferation” (also called “granulation”), which is the phase of tissue reconstruction and repair of defects in the injured area. New blood vessels and connective tissues begin forming thanks to the proliferation of endothelial cells combined with fibroblasts. The result is epithelial tissue formation that covers the wound surface.

• Duration: from 1 to 3 weeks or longer.
• Cells involved: fibroblasts and keratinocytes.
• Signs at the wound: formation of raspberry-like scabs on the wound surface, redness around the wound edges, itching sensation near the wound margins.
• Tasks: form new blood vessels and tissue to replace damaged cells and vessels.

• Mechanism:

Fibroblasts migrate within the wound, proliferate, and synthesize extracellular matrix (ECM), interacting with keratinocytes to form granulation tissue by:

Destroying proteins and blood clots => Producing collagen => Synthesizing new ECM rich in collagen, fibronectin, and hyaluronic acid => Stabilizing and arranging granulation tissue => Combining with keratinocytes to fill the wound.

The proliferation process starts at the wound edges and periphery then gradually progresses to the wound center.

• Stage 3: Epithelialization

Epithelialization is the final stage of the open wound healing process and the stage of scar formation. In this phase, blood vessels have been restored and the wound surface covered by new skin. However, skin elasticity and tissue function have not fully returned to their original state and continue to improve.

• Duration: about 3 months to 1-2 years.
• Cells involved: macrophages and fibroblasts.
• Signs at the wound: mild itching, dry surface, wound gradually closing.
• Tasks: restore tissue function and integrity.
• Mechanism:

Epidermal cells proliferate and migrate to cover new tissue. Meanwhile, fibroblasts differentiate into scar tissue, pulling wound edges together and contracting the wound. This phase lasts several months to 1-2 years until the wound is fully healed, resulting in a scar.

Scars lack sweat glands and hair follicles, are darker in color, feel harder, and often raised above normal skin surface.

3. Factors Affecting Wound Healing

Everyone wants the open wound healing process to be quick to restore skin and minimize scarring. However, healing time varies depending on the following factors:

• Local Factors Affecting Wound Healing

Wound hematoma or local ischemia

• Severity and type of crush or compression injuries
• Delayed treatment, wound infection
• Poor suturing technique; incorrect use of electrosurgery tools or settings

Systemic Factors Affecting Wound Healing

• Age: younger people tend to heal faster than older individuals due to variations in inflammatory response.
• Stress: anxiety and stress can slow wound recovery.
• Malnutrition: the healing process requires various nutrients like proteins, amino acids, carbohydrates, iron, zinc, copper, vitamins, and fats. Deficiencies delay healing.
• Obesity: slows skin healing and increases surgical wound complications.
• Smoking: increases infection risk, delays healing, and reduces skin elasticity.
• Alcohol consumption: delays clotting, collagen production, and tissue repair.
• Chronic diseases like diabetes or side effects of some drugs: delay wound healing by impairing clot formation, platelet function, and inflammatory responses.

4. Important Notes During Wound Healing

Some tips to help avoid bad scars or infection complications during open wound healing:

– Do not apply folk remedies or use medicines without doctor’s prescription as they may cause complications or infection.

– Avoid excessive movement or activity to promote faster wound closure. Follow medical instructions and get proper rest.

– Seek medical care if signs of infection like pus, redness, heat, or severe pain appear around the wound.

– Improper care or unsupervised medication can lead to scar discoloration.

– In the first weeks of healing, avoid direct sun exposure to the new skin. Use SPF 50 sunscreen and cover the wound when outside.

– Apply moisturizer daily to nourish skin and relax scars.

• Fast Healing Solution with Painless Dressing

To speed up healing of open wounds, consider using Urgo Medical’s home wound care products.

Unlike traditional dressings that may cause secondary tissue damage and have little healing effect, products using Urgo Medical’s exclusive Lipido-Colloid Technology (TLC) have been proven to promote wound healing with three advantages:

– Create a moist environment that provides optimal conditions for cell proliferation in the healing phase, promoting granulation and epithelialization.

– Stimulate fibroblast proliferation and production of collagen and hyaluronic acid to accelerate healing.

– Enable painless dressing changes without damaging the wound bed or granulation tissue, reducing care time.

Learn more about Urgo Medical’s exclusive TLC technology HERE.

*References:

1- Report for the Minister of Social Security and the French Parliament on health insurance expenditures and revenues in 2014 (Law of 13 August 2004) – July 2013.

2- Dr. Dao Dang Linh, Department of Trauma-Orthopedics, Military Hospital 108.

3- MSc, Dr. Le Quang Minh – Orthopedic Surgeon, General Surgery Department, Vinmec International Hospital Da Nang.