Wound Healing: Difference between revisions

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== Anatomy and Function of the Skin ==
== Introduction ==
Skin is the largest organ in the body and performs a wide variety of different functions. It is composed of a predominantly cellular epidermis and an underlying dermis, which is composed of fibers of connective tissue relatively sparsely populated with cells. They play an important role in the injury of the skin.<ref name=":0">David J Magee, James E. Zachazewski, and William S. Quillen,Pathology and intervention of muscloskeletal disorders.2nd ed,2008.</ref>[[File:Anatomy+of+the+Skin.jpg|thumb]]
[[Integumentary System|Skin]] is the largest organ in the body and covers the body's entire external surface.
[[File:Integumentary system - Kenhub.png|alt=Overview of the integumentary system (skin)|500x500px|Overview of the Integumentary System (Skin) <ref>Overview of the integumentary system (skin) image - © Kenhub. Available from; https://www.kenhub.com/en/library/anatomy/integumentary-system
</ref>|thumb]]


The ''<u>epidermis</u>'' contains mostly keratinocytes, among which are interspersed melanocytes, Merkel cells, Langerhans cells, and other resident immune cells.  
* Made up of three layers, the epidermis, dermis, and hypo-dermis.
* Skin's structure is made up of an intricate network that serves as the body’s initial barrier against pathogens, UV light, and chemicals, and mechanical injury, and regulates temperature and the amount of water released into the environment. 
<br>
A skin wound results from the breakdown of the epidermal layer integrity<ref>Yousef H, Alhajj M, Sharma S, Anatomy, Skin (integument), epidermis [Internet]. 2017 [cited 24 October 2020]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470464/</ref>. 
* Wound healing mostly means healing of the skin.
* Begins immediately after an injury to the epidermal layer and might take years.
* Dynamic process including highly organized cellular, humoral, and molecular mechanisms. 
* Has 3 overlapping phases which are inflammation, proliferation, and remodelling. Any disruption leads to abnormal wound healing<ref name=":3">Kangal MK, Regan JP, Wound Healing [Internet]. 2020 [cited 24 October 2020]. Available from:https://www.ncbi.nlm.nih.gov/books/NBK535406/</ref>.
<br>
See also [[Soft Tissue Healing]][[File:Wound healing phases.png|center|900x900px|alt=|thumb|Healing Timelines]]


'''Keratinocytes''' are responsible for the production of keratin, a fibrous structural protein that contributes to the strength and waterproofing of skin.  
== Types of Wounds ==
The definition of a wound in general is damage to the integrity of biological tissue, including skin, mucous membranes, and organ tissues.Wounds can be separated into open or closed wounds:
* '''Closed Wound:''' The surface of the skin is intact, but the underlying tissues may be damaged. e.g. contusions, haematomas, or Stage 1 [[Pressure Ulcers|Pressure Ul]]<nowiki/>[[Pressure Ulcers|ce]]<nowiki/>[[Pressure Ulcers|rs]].
* '''Open Wounds''': the skin is split or cracked and the underlying tissues are exposed to the outside environment.
<br>
<div class="row">
  <div class="col-md-6">[[Image:Tmp913957404729671681.jpg|center|alt=|Closed Wound - Contusion|thumb]]</div>
  <div class="col-md-6">[[Image:DxBdfBpaX3SpQbEbX7KHZ1J5.jpg|center|alt=|409x409px|Open Wound|thumb]]</div>
</div>Also it can be classified according to the cleanliness and condition of wounds into four classes of wound status:<ref>Herman TF, Bordoni B. Wound Classification. StatPearls Publishing; 2022.</ref>


'''Melanocytes''' protect against ultraviolet (UV) light, producing melanin, the dark pigment that gives the skin its color.
'''Class 1'''  


'''Langerhans cells''' are professional antigen-presenting cells and play critical roles in both protective immune responses in the skin and maintenance of immune homeostasis.
wounds are considered to be:


'''Merkel cells''' have been associated with discrimination of light touch.The epidermis also contains dermal appendages, such as hair follicles, sebaceous glands, eccrine sweat glands, and apocrine glands.
# clean
# uninfected
# no inflammation is present
# primarily closed
# these wounds do not enter respiratory, alimentary, genital, or urinary tracts.


The <u>dermis</u> is the layer between the epidermis and the subcutaneous tissue. It is made up of [[collagen]], elastic fibers, and an extrafibrillar matrix.The dermis is a highly vascularized structure . the deepest of which is the fascial plexus, located at the level of the deep muscle fascia. Overlying this, at the level of the superficial fascia, is the subcutaneous plexus. The next level is the subdermal plexus, an extensive vascular network situated at the junction between the reticular dermis and the subcutaneous tissue directly below, which has an important role in the distribution of blood to other regions of the cutaneous system. Superficial to the subdermal plexus is the subpapillary plexus, situated between the papillary and reticular dermis with capillary loops extending into the papillae. Blood flow between the subdermal and subpapillary plexus is achieved through a series of arterioles and venules and has an important role in regulation of body temperature and the metabolic supply of the skin.
'''Class 2'''


== Types of wound ==
wounds are considered to be:
[[File:DxBdfBpaX3SpQbEbX7KHZ1J5.jpg|thumb|200x200px]]
[[File:Tmp913957404729671681.jpg|thumb]]
Wounds can be separated into open or closed wounds. In a closed wound the surface of the skin is intact, but the underlying tissues may be damaged. Examples of closed wounds are contusions, hematomas, or stage 1 pressure ulcers. With open wounds the skin is split or cracked, and the underlying tissues are exposed to the outside environment.


== Types of Wound healing ==
# clean-contaminated
there are three types of wound healing :<ref name=":0" />
# lack unusual contamination
# Class 2 wounds enter the respiratory, alimentary, genital, or urinary tracts under controlled conditions.


1- Wound healing can occur by '''primary, secondary, or tertiary''' intention. If the edges of the wound can be readily approximated, wound healing of superficial or  partial- thickness wounds (i.e., epidermis and dermis) will  usually occur by '''primary intention'''.The wound will heal through the formation of granulation tissue and  reepithelialization and there should be little or no evidence of a scar.
'''Class 3'''  


2- When the wound covers a larger surface area and the margins cannot be readily approximated and/or tissue damage extends deeper than the dermis and into the subcutaneous tissue wound healing occurs by '''secondary intention'''. It involves wound contraction, along with angiogenesis ( formation of new blood vessels) and reepithelialization. Due to the presence of greater amounts of scar tissue for wounds that close by secondary intention, the regenerated tissues are not identical to the original tissues and only regain a portion of their original tensile strength, making them somewhat vulnerable to future injury. Wounds that heal by secondary intention should be monitored and protected until maturation of the scar tissue has occurred.
wounds are considered to be:


3- In wounds that contain a large degree of tissue damage, necrosis, or foreign debris, treatment may include delayed closure to ensure removal of these materials before closure of the skin. This process is known as '''delayed primary or tertiary healing.'''
# contaminated
# These are fresh, open wounds caused by an insult to sterile techniques or by gastrointestinal tract leakage into the wound.
# incisions that result in acute or lack of purulent inflammation are classified as class 3 wounds.


== Wound Healing stages in Adults ==
'''Class 4'''  
In adults, optimal wound healing should involve four continuous and overlapping phases: '''hemostasis, inflammation, proliferation, and remodeling''' .<ref name=":0" />[[File:4-STAGES-OF-WOUND-HEALING.png|thumb]]


=== Hemostasis ===
wounds are considered to be:
The first-stage wound healing concentrates on achieving  hemostasis (i.e., a relatively constant internal environment) and a provisional wound matrix. In open wounds, vascular constriction and fibrin clot formation will occur to prevent further blood loss.


Damage to the tissues also stimulates vasodilation with an increase in capillary permeability due to the release of histamine by injured mast cells. This will influence the release of chemotactic factors leading to leukocyte infiltration and thus the release of cytokines and growth factors, which allow the tissues to progress to the inflammatory phase.
# dirty-infected
# result from improperly cared for traumatic wounds.  
# demonstrate devitalized tissue


When injury to the skin first occurs, keratinocytes release a store of  interleukin-1 (IL-1). This proinflammatory cytokine is important in initiating the healing cascade.
== Types of Wound Healing ==
Wound healing is classified as primary, secondary, and tertiary wound healing.  


=== Inflammation ===
'''Primary Healing or primary intention'''
Other cytokines released during the transition from hemostasis to the inflammatory phase  include epidermal growth factor (EGF) and platelet-derived growth factor (PDGF), another  important substance in stimulating growth and function of fibroblasts and the formation of new tissue.
* Uncomplicated healing of a non-infected, well-approximated wound is defined as primary healing. e.g. [[Surgery and General Anaesthetic|Surgical]] wounds.
<br>'''Secondary Healing or secondary intention'''
* If the wound healing course in this wound is disrupted by [[Infectious Disease|infection]], dehiscence, hypoxia or [[Immune System|immune]] dysfunction, the secondary healing stage begins.
* During secondary healing, granulation tissue formation and epithelization over this new tissue take place. These types of wounds are more susceptible to infections and poor healing.


Neutrophil infiltration and migration of macrophages, shortly followed by lymphocyte infiltration into the wound, signal the start of the inflammatory phase.


Macrophages play a central role in tissue healing through their production of growth factors, cytokines, and chemokines, which are important in the modulation of the inflammatory response.
'''Tertiary healing or third intention'''


=== Proliferation ===
* it is delayed primary wound healing after 4–6 days.
As the process of phagocytosis cleanses the wound of debris, such as denatured matrix and damaged cells, there is a shift toward the proliferative or granulation phase of healing. The focus of healing during the proliferative phase is to cover the surface of the wound and restore the vascular network through the generation of granulation tissue. This stage is characterized by epithelial proliferation and migration over the provisional matrix within the bed of the wound.  
* This occurs when the process of secondary intention is intentionally interrupted and the wound is mechanically closed.  
* This usually occurs after granulation tissue has formed.


As blood cells enter the site of tissue injury, monocytes are converted to macrophages with the assistance of transforming growth factor beta (TGF-β), a substance released by degranulating platelets. The macrophages release basic fibroblast growth factor (bFGF), a substance that increases the proliferation and function of fibroblasts. It is thought that macrophages also release vascular endothelial growth factor (VEGF), which contributes to angiogenesis.  
== Wound Healing Stages in Adults ==
In adults, optimal wound healing should involve four continuous and overlapping phases: Haemostasis, inflammation, proliferation, and remodelling .<ref name=":0">Magee DJ, Zachazewski JE, Quillen WS. Pathology and intervention of musculoskeletal disorders. Elsevier Health Sciences, 2008.</ref>
=== '''Hemostasis Phase''' ===
The process of the wound being closed by clotting.
* Happens very quickly.
* Starts when [[Blood Physiology|blood]] leaks out of the body, then blood vessels constrict to restrict the blood flow.
* The platelets aggregate and adhere to the sub-endothelium surface within seconds of the rupture of a blood vessel's epithelial wall.
* After that, the first fibrin strands begin to adhere in about sixty seconds.
* As the fibrin mesh begins, the blood is transformed from liquid to gel through pro-coagulants and the release of prothrombin.
* The formation of a thrombus or clot keeps the platelets and blood cells trapped in the wound area.
* The thrombus is generally important in the stages of wound healing but becomes a problem if it detaches from the vessel wall and goes through the circulatory system, possibly causing a [[stroke]], [[Pulmonary Embolism|pulmonary embolism]] or [[Myocardial Infarction|heart attack]]<ref name=":4">Wound Source. Wound Healing[https://www.woundsource.com/blog/four-stages-wound-healing .] Available from:https://www.woundsource.com/blog/four-stages-wound-healing (last accessed 24 October 2020).</ref><ref name=":3" />.


During the proliferative phase, reduction in the number of macrophages or impairment in function can contribute to impaired wound closure and delayed formation of granulation tissue. Fibroblasts and endothelial cells are the predominant cell types in the wound during this phase, and they support capillary growth, collagen formation, and the formation of granulation tissue. Collagen is the major component of acute wound connective tissues.
=== '''Inflammatory Phase''' ===
* Begins right after the injury when the injured blood vessels leak transudate (made of water, salt, and protein) causing localized swelling.
* Inflammation both controls bleeding and prevents infection.
* The fluid engorgement allows healing and repair cells to move to the site of the wound.
* During the inflammatory phase, damaged cells, pathogens, and [[Bacterial Infections|bacteria]] are removed from the wound area.
* The [[Leukocytes|white blood cells]], growth factors, nutrients and [[Enzymes|enzyme]]<nowiki/>s create the swelling, heat, pain and redness commonly seen during this stage of wound healing.
* Inflammation is a natural part of the wound healing process and is only problematic if prolonged or excessive.


During the proliferative phase, its molecules are cross-linked and organized into bundles. In addition to producing collagen, fibroblasts also produce glycosaminoglycans and proteoglycans, all of which are major components of the extracellular substance of granulation tissue. Keratinocytes and endothelial cells produce autocrine growth factors, and, in synchrony with endothelial expansion, new blood vessels are formed by angiogenesis. As the fibrin clot and provisional matrix are degraded, there is simultaneous deposition of granulation tissue. Epithelial cells migrate inward until the wound is covered. Fibroblasts are transformed into myofibroblasts.
=== '''Proliferative Phase''' ===
When the wound is rebuilt with new tissue made up of [[collagen]] and extracellular matrix
* The wound contracts as new tissues are built.
* A new network of blood vessels must be constructed so that the granulation tissue can be healthy and receive sufficient oxygen and nutrients.
* Myofibroblasts cause the wound to contract by gripping the wound edges and pulling them together using a mechanism similar to that of smooth muscle cells.
* In healthy stages of wound healing, granulation tissue is pink or red and uneven in texture. Healthy granulation tissue does not bleed easily.
* Dark granulation tissue can be a sign of infection, ischemia, or poor perfusion.
* Finally epithelial cells resurface the injury.
* Epithelialization happens faster when wounds are kept moist and hydrated.
* Generally, when occlusive or semi-occlusive dressings are applied within 48 hours after injury, they will maintain correct tissue humidity to optimize epithelialization.


=== Remodling ===
=== '''Maturation Phase''' (Remodelling Stage) ===
Myofibroblasts are contractile cells, so wound contraction follows, leading to the  final stage of wound healing, the remodeling or maturation phase.The maturation or remodeling phase can last up to 1 year or longer post injury, particularly in full-thickness wounds and/or wounds involving larger surface areas of skin. During this time the formation of granulation tissue stops through the apoptosis (i.e., normal death of cells as part of the healing process) or exiting of macrophages, endothelial cells, and myofibroblasts. Therefore a mature wound can be classified as avascular and acellular.
* Collagen is remodelled from type III to type I and the wound fully closes.
* The cells that had been used to repair the wound but which are no longer needed are removed by [[apoptosis]], or programmed cell death.
* The collagen laid down during the proliferative phase, it is disorganized and the wound is thick.
*[[Collagen]] is remodelled into a more organized structure along lines of stress, thereby increasing the tensile strength of the healing tissues. Fibroblasts secrete matrix metalloproteinases. The enzymes facilitate remodelling of type III collagen to type I collagen<ref name=":0" />.
* Generally, remodelling begins about 21 days after an injury and can continue for a year or more.
* Even with cross-linking, healed wound areas continue to be weaker than uninjured skin, generally only having 80% of the tensile strength of unwounded skin<ref name=":4" />.


[[Collagen]] is remodeled into a more organized structure along lines of stress, thereby increasing the tensile strength of the healing tissues. Fibroblasts secrete matrix metalloproteinases. The enzymes facilitate remodeling of type III collagen to type I collagen, which is now organized in parallel bundles until the normal collagen ratio of 4 type III:1 type I is achieved.
== Clinical Significance ==
== Factors affecting the wound healing ==
Any disruption in wound healing phases leads to excessive wound healing or chronic wound formation.
'''Intrinsic factors''' include :age, nutrition, and hydration levels, location and depth of the wound, medications, and co-morbidities.  


'''Extrinsic''' factors include: support surfaces, friction, and shear and effective repositioning schedules.
=== Excessive Wound Healing ===
* The pathogenesis of the excessive wound healing is not fully understood.
* An abnormal form of a wound healing that is characterized by a continuous localized inflammation.
* Excessive collagen synthesis, abnormal collagen turnover and exaggerated ECM accumulation in these wounds. e.g. "Keloid" and "hypertrophic scars".


also there are other '''local factors''' like :<ref name=":1" />
=== Chronic Wound Formation ===
* Moisture; keeping a wound moist rather than dry makes wound healing more rapid and with less pain and less scarring
* A wound that has failed to heal in 4 weeks is defined as a chronic wound.
* Mechanical factors
* Risk Factors; Age, immune status, malnutrition, infection, insufficient oxygenation or perfusion, smoking, diseases, medications, [[Radiation Side Effects and Syndromes|radiation]], and [[Chemotherapy Side Effects and Syndromes|chemotherapy]] are the main risk factors.
* Edema
* Chronic wounds are usually classified as vascular ulcers [[Chronic Leg Ulcers|(venous or arterial ulcers]]), [[The Diabetic Foot|diabetic ulcers]], and [[Pressure Ulcers|pressure ulcers]].<ref name=":3" /> See image.
* Ionizing radiation
<br>Other Complications can include:
* Faculty technique of wound closure
* Deficient scar formation.
* Ischemia and necrosis
* Exuberant granulation.
* Foreign bodies.
* Deficient contraction (in skin grafts) or excessive contraction (in [[Burns Overview|burns]]).
* Low oxygen tension
* Others: Dystrophic calcification<ref>Enoch S, Kupitz S, Miller DR, Harding KG. Dystrophic calcification as a cause for non-healing leg ulcers. International Wound Journal. 2005; 2(2):142-7.</ref>, pigmentary changes<ref>Chadwick S, Heath R, Shah M. Abnormal pigmentation within cutaneous scars: a complication of wound healing. Indian journal of plastic surgery 2012; 45(2):403.</ref>, painful scars, incisional [[hernia]].<ref>Hope WW, Waheed A, Tuma F. Incisional hernia [Internet]. 2019. Available from:https://www.ncbi.nlm.nih.gov/books/NBK435995/</ref>
* Perfusion
and another '''systemic factors:'''
* Inflammation
* Diabetes .
* Nutrients.
* Metabolic diseases.
* Immunosuppression.
* Connective tissue disorders.
* Smoking.
* Alcohol .


== Complications of wound healing ==
== Factors Affecting the Wound Healing ==
# Deficient scar formation.
* Main Risk factors are: [[Older People Introduction|age,]] [[Immunocompromised Client|immune status]], malnutrition, infection, insufficient oxygenation or perfusion, [[Smoking Cessation and Brief Intervention|smoking]], [[diabetes]], [[Metabolic and Endocrine Disorders|metabolic diseases,]] [[Pain Medications|medications]], radiation, and chemotherapy<ref name=":3" />.  
# Excessive scar formation:
Also, consider:  
# Exuberant granulation.
* Extrinsic factors which include: support surfaces, friction, and shear and effective repositioning schedules.
# Deficient contraction (in skin grafts) or excessive contraction (in burns).
* Local factors: moisture (keeping a wound moist improves healing)<ref>Metzgerm S. Clinical and financial advantages of moist wound management. Home Healthcare Nurse. 2004; 22(9):586-90.</ref>; [[Peripheral Edema|edema]]; faulty technique of wound closure; Ischemia and necrosis; foreign bodies<ref>Iconomou TG, Zuker RM, Michelow BJ. Management of major penetrating glass injuries to the upper extremities in children and adolescents. Microsurgery. 1993;14(2):91-6.</ref>.
# Others: Dystrophic calcification, pigmentary changes, painful scars, incisional hern.<ref name=":1">https://en.wikipedia.org/wiki/Wound_healing</ref>


== Wound care in Physiotherapy ==
== Wound Care in Physiotherapy ==
'''The most common wounds that are treated by wound care physical therapist are:'''<ref name=":2">https://my.clevelandclinic.org/departments/rehabilitation/services/wound-care</ref>
'''The most common wounds that are treated by wound care physical therapist are:'''<ref name=":2">Cleveland Clinic. Wound care.https://my.clevelandclinic.org/departments/rehabilitation/services/wound-care (accessed 24 October 2020).</ref>
* Necrotic wounds.
* Necrotic wounds.
* Stage III, IV or unstageable pressure ulcers.
* Stage III, IV or unstageable pressure ulcers.
* Diabetic wounds.
* Diabetic wounds, see image.
* Chronic wounds.
* Chronic wounds.
* Venous and/or arterial wounds.
* Venous and/or arterial wounds.
* Extremity wounds with edema.
* Extremity wounds with oedema.
* Non-healing surgical wounds.
* Non-healing surgical wounds.


=== Physiotherapy role ===
== Physiotherapy Role ==
Patients must be referred by their physician to physical therapy wound care.Physical therapy wound care begins with a comprehensive evaluation and development of an individualized care plan. <ref name=":2" />
Physical therapy wound care begins with a comprehensive evaluation and the development of an individualized care plan. <ref name=":2" />
 
* [[Wound Assessment]]
Common treatment approaches can include:
* [[Wound Debridement]]
* Measurement and documentation of the wound characteristics
[[File:Forearm ulcer.jpg|right|frameless]]
* Cleaning of the wound
<br>Common treatment approaches can include:
* Debridement (removal) of any dead tissue
* Measurement and documentation of the wound characteristics.
* Selection and application of wound dressing
* Cleaning of the wound.
* Application of compression if necessary
* Debridement (removal) of any dead tissue.
* Selection and application of wound dressing.
* Application of compression if necessary.
* Education of the patient, caregivers and/or family members regarding wound care and dressing changes.
* Education of the patient, caregivers and/or family members regarding wound care and dressing changes.
and the available '''treatment modalities''' may include:
<br>Treatment modalities may include:
* Ultrasound mist therapy
* [[Ultrasound in Wound Healing|Ultrasound]] mist therapy
* Electrical stimulation
* Electrical stimulation
* Pulsed lavage
* Pulsed lavage
Line 123: Line 174:
* Negative pressure vacuum therapy
* Negative pressure vacuum therapy
* Compression therapy.
* Compression therapy.
== See also<ref>https://www.youtube.com/watch?v=533BpnWkXVU</ref> ==
{{#ev:youtube|533BpnWkXVU}}


== Related Resources ==
== Related Resources ==
Line 131: Line 179:


== References ==
== References ==
<references />


[[Category:Rehabilitation Foundations]]
[[Category:Rehabilitation Foundations]]
[[Category:Healing]]
[[Category:Healing]]
<references />
[[Category:Interventions]]
[[Category:Interventions]]
[[Category:Anatomy]]
[[Category:Older People/Geriatrics]]
[[Category:Older People/Geriatrics]]
[[Category:Older People/Geriatrics - Anatomy]]
[[Category:Older People/Geriatrics - Interventions]]
[[Category:Older People/Geriatrics - Interventions]]
[[Category:Physiology]]

Latest revision as of 13:36, 11 January 2024

Original Editor - Esraa Mohamed Abdullzaher

Top Contributors - Esraa Mohamed Abdullzaher, Naomi O'Reilly, Lucinda hampton, Kim Jackson, Olajumoke Ogunleye, Joao Costa, Claire Knott, Admin, Lauren Lopez and Aya Alhindi  

Introduction[edit | edit source]

Skin is the largest organ in the body and covers the body's entire external surface.

Overview of the integumentary system (skin)
Overview of the Integumentary System (Skin) [1]
  • Made up of three layers, the epidermis, dermis, and hypo-dermis.
  • Skin's structure is made up of an intricate network that serves as the body’s initial barrier against pathogens, UV light, and chemicals, and mechanical injury, and regulates temperature and the amount of water released into the environment. 


A skin wound results from the breakdown of the epidermal layer integrity[2]. 

  • Wound healing mostly means healing of the skin.
  • Begins immediately after an injury to the epidermal layer and might take years.
  • Dynamic process including highly organized cellular, humoral, and molecular mechanisms. 
  • Has 3 overlapping phases which are inflammation, proliferation, and remodelling. Any disruption leads to abnormal wound healing[3].


See also Soft Tissue Healing

Healing Timelines

Types of Wounds[edit | edit source]

The definition of a wound in general is damage to the integrity of biological tissue, including skin, mucous membranes, and organ tissues.Wounds can be separated into open or closed wounds:

  • Closed Wound: The surface of the skin is intact, but the underlying tissues may be damaged. e.g. contusions, haematomas, or Stage 1 Pressure Ulcers.
  • Open Wounds: the skin is split or cracked and the underlying tissues are exposed to the outside environment.


Closed Wound - Contusion
Open Wound

Also it can be classified according to the cleanliness and condition of wounds into four classes of wound status:[4]

Class 1

wounds are considered to be:

  1. clean
  2. uninfected
  3. no inflammation is present
  4. primarily closed
  5. these wounds do not enter respiratory, alimentary, genital, or urinary tracts.

Class 2

wounds are considered to be:

  1. clean-contaminated
  2. lack unusual contamination
  3. Class 2 wounds enter the respiratory, alimentary, genital, or urinary tracts under controlled conditions.

Class 3

wounds are considered to be:

  1. contaminated
  2. These are fresh, open wounds caused by an insult to sterile techniques or by gastrointestinal tract leakage into the wound.
  3. incisions that result in acute or lack of purulent inflammation are classified as class 3 wounds.

Class 4

wounds are considered to be:

  1. dirty-infected
  2. result from improperly cared for traumatic wounds.
  3. demonstrate devitalized tissue

Types of Wound Healing[edit | edit source]

Wound healing is classified as primary, secondary, and tertiary wound healing.

Primary Healing or primary intention

  • Uncomplicated healing of a non-infected, well-approximated wound is defined as primary healing. e.g. Surgical wounds.


Secondary Healing or secondary intention

  • If the wound healing course in this wound is disrupted by infection, dehiscence, hypoxia or immune dysfunction, the secondary healing stage begins.
  • During secondary healing, granulation tissue formation and epithelization over this new tissue take place. These types of wounds are more susceptible to infections and poor healing.


Tertiary healing or third intention

  • it is delayed primary wound healing after 4–6 days.
  • This occurs when the process of secondary intention is intentionally interrupted and the wound is mechanically closed.
  • This usually occurs after granulation tissue has formed.

Wound Healing Stages in Adults[edit | edit source]

In adults, optimal wound healing should involve four continuous and overlapping phases: Haemostasis, inflammation, proliferation, and remodelling .[5]

Hemostasis Phase[edit | edit source]

The process of the wound being closed by clotting.

  • Happens very quickly.
  • Starts when blood leaks out of the body, then blood vessels constrict to restrict the blood flow.
  • The platelets aggregate and adhere to the sub-endothelium surface within seconds of the rupture of a blood vessel's epithelial wall.
  • After that, the first fibrin strands begin to adhere in about sixty seconds.
  • As the fibrin mesh begins, the blood is transformed from liquid to gel through pro-coagulants and the release of prothrombin.
  • The formation of a thrombus or clot keeps the platelets and blood cells trapped in the wound area.
  • The thrombus is generally important in the stages of wound healing but becomes a problem if it detaches from the vessel wall and goes through the circulatory system, possibly causing a stroke, pulmonary embolism or heart attack[6][3].

Inflammatory Phase[edit | edit source]

  • Begins right after the injury when the injured blood vessels leak transudate (made of water, salt, and protein) causing localized swelling.
  • Inflammation both controls bleeding and prevents infection.
  • The fluid engorgement allows healing and repair cells to move to the site of the wound.
  • During the inflammatory phase, damaged cells, pathogens, and bacteria are removed from the wound area.
  • The white blood cells, growth factors, nutrients and enzymes create the swelling, heat, pain and redness commonly seen during this stage of wound healing.
  • Inflammation is a natural part of the wound healing process and is only problematic if prolonged or excessive.

Proliferative Phase[edit | edit source]

When the wound is rebuilt with new tissue made up of collagen and extracellular matrix

  • The wound contracts as new tissues are built.
  • A new network of blood vessels must be constructed so that the granulation tissue can be healthy and receive sufficient oxygen and nutrients.
  • Myofibroblasts cause the wound to contract by gripping the wound edges and pulling them together using a mechanism similar to that of smooth muscle cells.
  • In healthy stages of wound healing, granulation tissue is pink or red and uneven in texture. Healthy granulation tissue does not bleed easily.
  • Dark granulation tissue can be a sign of infection, ischemia, or poor perfusion.
  • Finally epithelial cells resurface the injury.
  • Epithelialization happens faster when wounds are kept moist and hydrated.
  • Generally, when occlusive or semi-occlusive dressings are applied within 48 hours after injury, they will maintain correct tissue humidity to optimize epithelialization.

Maturation Phase (Remodelling Stage)[edit | edit source]

  • Collagen is remodelled from type III to type I and the wound fully closes.
  • The cells that had been used to repair the wound but which are no longer needed are removed by apoptosis, or programmed cell death.
  • The collagen laid down during the proliferative phase, it is disorganized and the wound is thick.
  • Collagen is remodelled into a more organized structure along lines of stress, thereby increasing the tensile strength of the healing tissues. Fibroblasts secrete matrix metalloproteinases. The enzymes facilitate remodelling of type III collagen to type I collagen[5].
  • Generally, remodelling begins about 21 days after an injury and can continue for a year or more.
  • Even with cross-linking, healed wound areas continue to be weaker than uninjured skin, generally only having 80% of the tensile strength of unwounded skin[6].

Clinical Significance[edit | edit source]

Any disruption in wound healing phases leads to excessive wound healing or chronic wound formation.

Excessive Wound Healing[edit | edit source]

  • The pathogenesis of the excessive wound healing is not fully understood.
  • An abnormal form of a wound healing that is characterized by a continuous localized inflammation.
  • Excessive collagen synthesis, abnormal collagen turnover and exaggerated ECM accumulation in these wounds. e.g. "Keloid" and "hypertrophic scars".

Chronic Wound Formation[edit | edit source]


Other Complications can include:

  • Deficient scar formation.
  • Exuberant granulation.
  • Deficient contraction (in skin grafts) or excessive contraction (in burns).
  • Others: Dystrophic calcification[7], pigmentary changes[8], painful scars, incisional hernia.[9]

Factors Affecting the Wound Healing[edit | edit source]

Also, consider:

  • Extrinsic factors which include: support surfaces, friction, and shear and effective repositioning schedules.
  • Local factors: moisture (keeping a wound moist improves healing)[10]; edema; faulty technique of wound closure; Ischemia and necrosis; foreign bodies[11].

Wound Care in Physiotherapy[edit | edit source]

The most common wounds that are treated by wound care physical therapist are:[12]

  • Necrotic wounds.
  • Stage III, IV or unstageable pressure ulcers.
  • Diabetic wounds, see image.
  • Chronic wounds.
  • Venous and/or arterial wounds.
  • Extremity wounds with oedema.
  • Non-healing surgical wounds.

Physiotherapy Role[edit | edit source]

Physical therapy wound care begins with a comprehensive evaluation and the development of an individualized care plan. [12]

Forearm ulcer.jpg


Common treatment approaches can include:

  • Measurement and documentation of the wound characteristics.
  • Cleaning of the wound.
  • Debridement (removal) of any dead tissue.
  • Selection and application of wound dressing.
  • Application of compression if necessary.
  • Education of the patient, caregivers and/or family members regarding wound care and dressing changes.


Treatment modalities may include:

  • Ultrasound mist therapy
  • Electrical stimulation
  • Pulsed lavage
  • Whirlpool
  • Negative pressure vacuum therapy
  • Compression therapy.

Related Resources[edit | edit source]

Ultrasound in Wound Healing

References[edit | edit source]

  1. ↑ Overview of the integumentary system (skin) image - © Kenhub. Available from; https://www.kenhub.com/en/library/anatomy/integumentary-system
  2. ↑ Yousef H, Alhajj M, Sharma S, Anatomy, Skin (integument), epidermis [Internet]. 2017 [cited 24 October 2020]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470464/
  3. ↑ 3.0 3.1 3.2 3.3 Kangal MK, Regan JP, Wound Healing [Internet]. 2020 [cited 24 October 2020]. Available from:https://www.ncbi.nlm.nih.gov/books/NBK535406/
  4. ↑ Herman TF, Bordoni B. Wound Classification. StatPearls Publishing; 2022.
  5. ↑ 5.0 5.1 Magee DJ, Zachazewski JE, Quillen WS. Pathology and intervention of musculoskeletal disorders. Elsevier Health Sciences, 2008.
  6. ↑ 6.0 6.1 Wound Source. Wound Healing. Available from:https://www.woundsource.com/blog/four-stages-wound-healing (last accessed 24 October 2020).
  7. ↑ Enoch S, Kupitz S, Miller DR, Harding KG. Dystrophic calcification as a cause for non-healing leg ulcers. International Wound Journal. 2005; 2(2):142-7.
  8. ↑ Chadwick S, Heath R, Shah M. Abnormal pigmentation within cutaneous scars: a complication of wound healing. Indian journal of plastic surgery 2012; 45(2):403.
  9. ↑ Hope WW, Waheed A, Tuma F. Incisional hernia [Internet]. 2019. Available from:https://www.ncbi.nlm.nih.gov/books/NBK435995/
  10. ↑ Metzgerm S. Clinical and financial advantages of moist wound management. Home Healthcare Nurse. 2004; 22(9):586-90.
  11. ↑ Iconomou TG, Zuker RM, Michelow BJ. Management of major penetrating glass injuries to the upper extremities in children and adolescents. Microsurgery. 1993;14(2):91-6.
  12. ↑ 12.0 12.1 Cleveland Clinic. Wound care.https://my.clevelandclinic.org/departments/rehabilitation/services/wound-care (accessed 24 October 2020).
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