Chapter 5 The Healing Process. Overview Injuries to the musculoskeletal system can result from a wide variety of causes. Each of the major components

Chapter 5Chapter 5

The Healing ProcessThe Healing Process

OverviewOverview

Injuries to the musculoskeletal Injuries to the musculoskeletal system can result from a wide system can result from a wide variety of causesvariety of causes. . Each of the Each of the major components of the major components of the musculoskeletal systemmusculoskeletal system have have varying capacities to healvarying capacities to heal

Musculoskeletal Musculoskeletal InjuriesInjuries Injuries to the soft tissues can be Injuries to the soft tissues can be

classified as primary or secondaryclassified as primary or secondary::– Primary Primary injuries can be self-inflicted, injuries can be self-inflicted,

caused by another individual or entity, caused by another individual or entity, or caused by the environmentor caused by the environment

AcuteAcute ChronicChronic Acute on chronicAcute on chronic

Musculoskeletal Musculoskeletal InjuriesInjuries Secondary Secondary injuries are essentially injuries are essentially

the inflammatory response that the inflammatory response that occurs with the primary injuryoccurs with the primary injury

Wound healingWound healing

Fortunately, the majority of soft tissue Fortunately, the majority of soft tissue injuries heal without complication in a injuries heal without complication in a predictable series of eventspredictable series of events

However, healing abnormalities can However, healing abnormalities can occur. These abnormalities can be due occur. These abnormalities can be due to such complications as:to such complications as:– InfectionInfection– Compromised circulationCompromised circulation– NeuropathyNeuropathy

Wound healingWound healing

Three main phases:Three main phases:– InflammatoryInflammatory– ProliferativeProliferative– RemodelingRemodeling

Inflammatory phaseInflammatory phase

The reaction that occurs The reaction that occurs immediately after wounding immediately after wounding includes a series of defensive includes a series of defensive events that involves the events that involves the recognition of a pathogen and the recognition of a pathogen and the mounting of a reaction against it. mounting of a reaction against it. This reaction involves both This reaction involves both coagulation and inflammationcoagulation and inflammation


Coagulation. Apart from an initial period Coagulation. Apart from an initial period of vasoconstriction lasting for 5-10 of vasoconstriction lasting for 5-10 minutes, tissue injury causes minutes, tissue injury causes vasodilation, the disruption of blood vasodilation, the disruption of blood vessels and extravasation of blood vessels and extravasation of blood constituents, including platelets constituents, including platelets

The main functions of the exudate are to:The main functions of the exudate are to:– Provide cells capable of tissue reconstructionProvide cells capable of tissue reconstruction– Dilute microbial toxinsDilute microbial toxins– Remove contaminants present in the woundRemove contaminants present in the wound


Inflammation. Inflammation is mediated Inflammation. Inflammation is mediated by chemotactic substances, including by chemotactic substances, including anaphylatoxinsanaphylatoxins, which , which attract neutrophils attract neutrophils and monocytesand monocytes– Neutrophils are white blood cells that bind to Neutrophils are white blood cells that bind to

microorganisms, internalize them, and kill microorganisms, internalize them, and kill themthem

– Monocytes are white blood cells that develop Monocytes are white blood cells that develop into macrophages, and provide into macrophages, and provide immunological defences against many immunological defences against many infectious organisms infectious organisms


The complete removal of the The complete removal of the wound debris marks the end of wound debris marks the end of the inflammatory processthe inflammatory process

This stage can last from 1-6 days This stage can last from 1-6 days to longer than 6 monthsto longer than 6 months

Common causes for a persistent Common causes for a persistent chronic inflammatory response include:chronic inflammatory response include:– Infectious agentsInfectious agents– Persistent virusesPersistent viruses– Hypertrophic scarringHypertrophic scarring– Poor blood supplyPoor blood supply– EdemaEdema– Repeated direct traumaRepeated direct trauma– Excessive tension at the wound siteExcessive tension at the wound site– Hypersensitivity reactionsHypersensitivity reactions


Clinically, during the inflammatory Clinically, during the inflammatory phase there is pain:phase there is pain:– At restAt rest– With active motionWith active motion– When specific stress is applied to the When specific stress is applied to the

injured structureinjured structure The pain, if severe enough, can result The pain, if severe enough, can result

in muscle guarding, and a loss of in muscle guarding, and a loss of function. function.

Proliferative phaseProliferative phase

Characteristic changes during this Characteristic changes during this phase include:phase include:– Capillary growthCapillary growth– Granulation tissue formationGranulation tissue formation– Fibroblast proliferation with collagen Fibroblast proliferation with collagen

synthesis and increased synthesis and increased macrophage and mast cell activitymacrophage and mast cell activity

Proliferative phaseProliferative phase

This phase lasts from 5 to 15 This phase lasts from 5 to 15 days, and often up to 10 weeks days, and often up to 10 weeks depending on the type of tissue, depending on the type of tissue, and the extent of damage. and the extent of damage.

Remodeling phaseRemodeling phase

The remodeling phase of wound The remodeling phase of wound healing involves a conversion of healing involves a conversion of the initial healing tissue to scar the initial healing tissue to scar tissuetissue

This lengthy phase of contraction, This lengthy phase of contraction, tissue remodeling and increasing tissue remodeling and increasing tensile strength in the wound tensile strength in the wound lasts for up to a yearlasts for up to a year

Remodeling phaseRemodeling phase

Imbalances in collagen synthesis and Imbalances in collagen synthesis and degradation during this phase of degradation during this phase of healing may result in hypertrophic healing may result in hypertrophic scarring or keloid formationscarring or keloid formation

If left untreated, the scar formed is less If left untreated, the scar formed is less than 20% of its original sizethan 20% of its original size

Scarring that occurs parallel to the line Scarring that occurs parallel to the line of force of a structure is less vulnerable of force of a structure is less vulnerable to re-injury than a scar, which is to re-injury than a scar, which is perpendicular to those lines of force perpendicular to those lines of force

Muscle healingMuscle healing

The capacity of muscle for The capacity of muscle for regeneration is based primarily upon regeneration is based primarily upon the type and extent of injurythe type and extent of injury

Broadly speaking, there are three Broadly speaking, there are three phases in the healing process of an phases in the healing process of an injured muscle: injured muscle: – The destruction phaseThe destruction phase– The repair phaseThe repair phase– The remodeling phaseThe remodeling phase

Ligament and tendon Ligament and tendon healinghealing Healing of ligaments and tendons Healing of ligaments and tendons

generally can be broken down generally can be broken down into four overlapping phases:into four overlapping phases: – I. I. HemorrhagicHemorrhagic– II.II. Inflammatory Inflammatory – III. III. ProliferationProliferation – IV. IV. Remodeling and maturationRemodeling and maturation

Articular cartilage Articular cartilage healinghealing The capacity of articular cartilage The capacity of articular cartilage

for repair is limitedfor repair is limited The repair response of articular The repair response of articular

cartilage varies with the depth of cartilage varies with the depth of the injurythe injury

Articular cartilage Articular cartilage healinghealing Injuries of the articular cartilage Injuries of the articular cartilage

that do not penetrate the that do not penetrate the subchondral bone become subchondral bone become necrotic and do not healnecrotic and do not heal

These lesions usually progress to These lesions usually progress to the degeneration of the articular the degeneration of the articular surfacesurface

Articular cartilage Articular cartilage healinghealing Injuries that penetrate the Injuries that penetrate the

subchondral bone undergo repair subchondral bone undergo repair due to access to the bone’s blood due to access to the bone’s blood supplysupply

These repairs are usually These repairs are usually characterized as:characterized as:– FibrousFibrous– FibrocartilaginousFibrocartilaginous– Hyaline-like cartilaginousHyaline-like cartilaginous

Bone healingBone healing

The striking feature of bone The striking feature of bone healing, compared to healing in healing, compared to healing in other tissues, is that repair is by other tissues, is that repair is by the original tissue, not scar tissuethe original tissue, not scar tissue

Bone healing involves a Bone healing involves a combination of intramembranous combination of intramembranous and endochondral ossificationand endochondral ossification


In classic histologic terms, In classic histologic terms, fracture healing has been divided fracture healing has been divided into two broad phases:into two broad phases:– Primary fracture healingPrimary fracture healing– Secondary fracture healingSecondary fracture healing


Primary healing involves a direct Primary healing involves a direct attempt by the cortex to attempt by the cortex to reestablish itself once it has reestablish itself once it has become interruptedbecome interrupted

Bone on one side of the cortex Bone on one side of the cortex must unite with bone on the other must unite with bone on the other side of the cortex to reestablish side of the cortex to reestablish mechanical continuitymechanical continuity


Secondary healing involves Secondary healing involves responses in the periosteum and responses in the periosteum and external soft tissues with the external soft tissues with the subsequent formation of a callussubsequent formation of a callus

The majority of fractures heal by The majority of fractures heal by secondary fracture healingsecondary fracture healing

Documents

Chapter 5 The Healing Process. Overview Injuries to the musculoskeletal system can result from a wide variety of causes. Each of the major components