Understanding the Healing Process

The Phases of Tissue Healing and The Healing Process of Various Body Tissues

 

Phases of the Healing Process

Inflammatory Response Phase

 Fibroblastic Repair Phase

 Maturation/RemodelingPhase

 

 

Inflammatory Response Phase

A series of events occurring in vascular tissues in response to injury or antigen, pathogen or allergen which causes infection, illness or allergic reaction

 

Contrasting Immune & Inflammatory Response:

 

 

 

 

KEY POINT:  Inflammation is an immediate response whereas an immune response develops more slowly

 

 

When does it Begin?

 

 

KEY POINT:   Inflammation is essential for tissue repair-without inflammation healing does not occur

 

Chemical Mediators

   Histamine:increased permeability, vasodilation

   Leukotaxin:increased local permeability, leukocytes line up along cell walls

   Necrosin:controls phagocytic activity

 

What are the characteristics of inflammation?

How and why do they occur?

Characteristics of Inflammation

   Swelling:

 

   Redness:

 

   Heat:

 

   Pain:

 

   Loss of Function:

 

 

What is the purpose of the inflammatory phase?

 

 

Control effects of injury

Return tissue to normal state by localizing & disposing of injury by-products to set stage for repair

 

 

Steps in Inflammatory Response

Immediate vasoconstriction (5-10’)

Vasodilation

Clot formation (platelet plug)

Phagocytosis

 

 

 

Chronic Inflammation

State in which the s/sxs of inflammation persist beyond the “normal” length of time

 

Sources of Chronic Inflammation:

Contamination by foreign body or bacteria

 

Invasion by microorganism able to survive within large phagocytes

 

Antigen-Antibody Reactions

 

Constant irritation by mechanical stresses or chemical and particulate matter

 

 

Fibroblastic Repair Phase

Fibroplasia

Regenerative activity that leads to scar formation/repair of injured tissues

 

Fibroblastic Repair Phase

  Characterized:

Decrease s/sxs of inflammation

Decreased pt. Tenderness

Decreased pain w/movements that stress tissue

 

 

  When does it occur?

 

 

Fibroblastic Repair Process

   Capillary Buds grow into area

   Fibroblasts accumulate at wound site

   Matrix is synthesized

   Fibroblasts: glue ends together

Type III Collagen

   Stable scar is created/fibroblasts diminish

   Remodeling ready to begin

 

 

 

Remodeling/Maturation Phase

When does it occur?

 

 

 

Maturation/Remodeling Process

   Realignment/Remodeling of collagen fibers

Type III collagen replaced w/ Type I collagen

   Remodeling is dependent on forces to which scar is subjected during maturation process: Wolff’s Law

   Assumes “normal” tissue type & function

What is the role of progressive mobility during the healing process?

 

 

 

 

 

 

 

 

 

 

Sample Time FrameMCL Injury

0-30 min Injury/Degeneration

0-36 hrs Coagulation/Platelet Plug

2h-2 wks Inflammatory Phase

48h-6 wks Repair Phase

3wks-2yrs Maturation/Remodeling

 

*6 wks: Tensile strength of healing tissue relatively normal

 

Tissue Repair Issues:

Regeneration v. Scarring:

 

Stabile Cells:

 

Labile Cells:

 

Permanent Cells:

 

 

Factors Which Impede Healing

    Extent of Injury

 

    Edema

 

    Hemorrhage

 

    Poor Vascular Supply

 

    Tissue Separation

 

    Muscle Spasm

 

    Atrophy

 

    Health, Age, Nutrition

 

    Corticosteroids

 

    Keloids/Hypertrophic Scars

 

    Infection

 

    Climate

 

 

Healing Process of Various Body Tissues

 

Ligament Healing

What do ligaments do?

   Healing Process

What effect does surgical repair have on ligament healing?

 

 

What effect does exercise have on ligament healing?

 

 

 

Insertion Healing: Ligament/Capsule/Tendon into Bone

What is the purpose of insertions?

 

 

 

Direct Insertions

     Insert perpendicularly into bone

     Low number of fiber attachments

     4 Zones

   Tendon/Ligament

   Fibrocartilage

   Mineralized Fibrocart.

   Bone

 

 

Superficial Insertions

   Blend in gradually w/periosteum

   Superficial and Deep Layers

 

 

Insertion Healing Concerns

    Avascular Tissue

    PAINFUL-slows healing

    Immobilization may be required

 

 

 

Bone Healing

    Fracture Occurs

    Clot is formed

    Matrix synthesized by Fibroblasts

    Chondroblasts enter area

    Callus is formed

    Stage of Clinical Union

    Osteoblasts calcify callus

    Remodeling: Osteoblasts/Osteoclasts

 

 

Factors Affecting Bone Healing

   Age

Femoral Shaft Fx

Time to Clinical Union

Birth 3 wks

8 yoa 8 wks

12 yoa 12wks

20 yoa 20 wks

 

   Site/Configuration

    Surrounding tissues

    Surface area

 

   Initial Displacement

    Continuity

 

   Blood Supply

    Mal Union

 

    Delayed Union

 

    Non-Union

 

    Fibrous Union

 

    Pseudo Union

 

 

Articular Cartilage Structure

    4-5 layers (1-5 mm thick)

Jt Space

20% Superficial Zone

 

50% Middle Transitional

 

30% Deep (Radial)

Tidemark

Calcified Cartilage

Subchondral Bone

 

Articular Cartilage Healing

    Does injury involve subchondral bone?

 

Cartilage alone

    no clot

    Neighboring chondrocytes

Subchondral Bone

    Inflammatory Process

    Defect replaced w/fibrocartilage

 

    Volume & Surface area

 

 

    Location of Injury to Joint

 

 

Methods for Facilitating Articular Cartilage Healing

   Shaving

 

   Drilling

 

   K-wire

 

    Osteochondral Autograft

 

    Autologous Cartilage Cell Implantation

 

 

Meniscus Structure

FEMUR

Superficial

Surface

Middle

Surface

Superficial

TIBIA

 

 

Factors Affecting Meniscus Healing

   Vascularity

 

   Extent of Tear

 

   Age

 

   Communication w/other Tissue

 

Muscle Healing

 

 

 

 

Muscle Healing Process:

   Follows standard healing process

   Fibroblasts lay down scar

   Myoblasts enter scar (new muscle cells)

   Responds to Wolff’s Law

   Fairly lengthy rehab process (Why??)

 

 

 

   4-8 wks until return to full activity

 

 

 

Tendon

    Purpose?

 

 

    Injuries include:

  Acute strain

  Tendinitis

 

 

Tendon Healing Process:

Extrinsic

    Disrupts blood supply

    Follows standard phases

    Tenocytes (repair cell)

    Requires strong union

    Problems w/adhesions

Why?? Related to anatomy.

 

 

 

Intrinsic

    No vessel damage

    Neighboring tenocytes attempt to fill in defect

    More prone to chronic inflammatory condition (Why?)

Tendon Healing Time Frame

 

 

Dependent Upon:

   Cross sectional area of injury

   Amount of force to be imposed

 

   Minimum 4-5 wks to resist forces that might pull it apart

 

 

 

Myotendinous Junction

   Common site of repeat failure & inflammation

   Scar less elastic than original tissue

   Responds to Wolff’s Law

 

 

 

Epithelial Tissue

    Covers all internal & external body surfaces

    Fibers arranged in a meshwork

  Resist stretch/failure in many directions

    Langer’s Lines: predominate lines in mesh

  Trunk: circumferential

  Extremities: longitudinal

What effect will this have on the way incisions are/should be made?

 

 

 

Epithelial Tissue Healing

   No true blood supply

   Receives nutrients/eliminates waste by diffusion

   Scar Tissue: more collagen than normal skin therefore less elastic

   APPROXIMATION is the Key!

 

 

 

Nerve Healing

   Once nerve cell dies cannot regenerate

   If cell body is not involved, peripheral nerves can regenerate some

   SLOW PROCESS, 3-4 mm/day

   CNS: SLOWER!