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Concepts of Healing

HealingHealing

By secondary intention:

Separation is largeTissue must fill spaceMore scar, longer healing time

By primary intention:

Separation is smallBridge of cells binds ends of wound together

Minor wounds, suture wounds

Tissue Healing PhasesTissue Healing Phases

Inflammation PhaseInflammation Phase

Occurs during first 3-5 days

Complex cellular and chemical interactions take place

Macrohages replace PMNs in 24-48 h to debride area

Neutrophils abound

Signs of InflammationSigns of Inflammation

Redness

Temperature increase

Edema

Pain

Reduced function

The signs of inflammation occur because of the increased metabolic activity and fluid in the region and the tissue damage that has occurred. Loss of function is produced by the primary signs of inflammation.

Causes of InflammationCauses of Inflammation

Proliferation PhaseProliferation Phase

Duration: 2-4 weeks

Angiogenesis and granulation tissue formation

Increased fibroblasts by day 3-5 following injury; reduced PMNs

By day 12, type I collagen replacing type III

Type III collagen formed

Signs of ProliferationSigns of Proliferation

Redness

Swelling

Pain

Local temperature

Remodeling PhaseRemodeling Phase

Lasts 6-18 months

Myofibroblasts cause wound contraction to minimize scar

Tensile strength increases

Collagen transition—type I replaces type III

Capillaries diminish in number

Signs of RemodelingSigns of Remodeling

Reduced redness

Reduced edema

Reduced pain

No local temperature

Growth FactorsGrowth Factors

Proteins

Perform important roles in healing process

Specific growth factors impact specific cells

Named for target cells, source, behavior

Roles of Growth Factors Roles of Growth Factors in Healingin Healing

Control migration and proliferation of cells

Affect fibrin-plug formation

Stimulate type III collagen degradation, type I synthesis

Control phagocytization

Assist capillary endothelial production

Ligament HealingLigament HealingSite fills with erythrocytes, leukocytes, lymphocytes.

Monocytes and macrophages infiltrate.

Near-normal tensile strength is restored at week 40-50.

Fibroblasts appear, increase, produce extracellular matrix.

Cellular and matrix structures replace the blood clot.Macrophages, fibroblasts diminish; type I collagen replaces type III.

Tendon HealingTendon Healing

Wound gap filled by phagocytes

Fibroblasts revert to tenocytes; type III collagen replaced with type I

Strength is 85-95% normal at week 40-50

Collagen synthesisFibroblast proliferation; revascularization; synovial sheath rebuilt

Muscle HealingMuscle HealingFragmentation of muscle fibers; macrophages appear

Appearance of fibroblasts; reduced muscle tension; phagocytes

Contraction ability: 90% normal at 6 weeks to 6 months

Day 7: scar tissue; near-normal muscle tension can be producedDay 7-11: near-normal tensile strength

Regenerating myotubes; cross-striated muscle fibers

Articular Cartilage HealingArticular Cartilage Healing

Fibrin clot is formedFibroblasts combine with collagen fibers to replace clot

1 month—Fibroblasts differentiate; chondrocytes appear

6 months—type I and II calcified cartilage with normal appearance

2 months—defect resembles cartilage, but collagen is type I

Bone HealingBone HealingPMNs, plasma, lymphocytes

Fibroblasts invade

3-4 months: Fracture is healedWeek 12: near-normal strength restored

Hematoma forms; fractured edges become necroticOsteoclasts proliferate; hard callus developsExternal blood supply dominates; then medullary circulation reestablished

tensile strength: maximal amount of stress or force that a structure is able to withstand before tissue failure occurs—in this case, the amount of outside force that can be applied to a muscle, tendon, ligament, or bone before it tears or breaks

Tensile Strength During Tensile Strength During Healing PhasesHealing Phases

Inflammation

Rapid decline to 50%Source of tensile strength: fibrin clot

Source of tensile strength: collagen, granulation tissue, ground substance

Proliferation

Increase in tensile strength

(continued)

Tensile Strength During Tensile Strength During Healing PhasesHealing Phases

Remodeling

Bone 83% of normal in 12 weeksLigament and tendon near normal in 17-50 weeksFull tensile strength never regained

For a therapeutic exercise program to be successful, one must have respect for the healing process and a knowledge of tensile strength factors.

Healing and Tensile Healing and Tensile StrengthStrength

Factors That Affect Factors That Affect HealingHealing

Modalities

Medications/Drugs

Other modifying factors (age, disease, etc.)

Treatment ModalitiesTreatment Modalities

Ice

Electrical stimulation

Deep heat

Superficial heat

Influence of Modalities Influence of Modalities on Healingon Healing

Relieve pain, spasm, edema

Enhance protein synthesis

Promote myofibroblast production

Retard atrophy, facilitate muscle activity

Improve circulationEnhance collagen and neovascular production

half-life: the amount of time it takes for the level of a drug in the bloodstream to decrease by half

Factors in Medication Factors in Medication EffectivenessEffectiveness

steady state of a drug: the state in which the average level of a drug remains constant in the blood—the amount of drug leaving the body is equal to the amount being absorbed

Effects of NSAIDs Effects of NSAIDs on Healingon Healing

Inhibit prostaglandin production

Increase blood clotting time

Absorption rate decreased when NSAIDs used with antacids

Decrease the effectiveness of other drugs

Drugs That Can Delay Drugs That Can Delay HealingHealing

Antibiotics

Antineoplastic drugs

Corticosteroids

HeparinNicotine

Other Modifying Factors Other Modifying Factors That Can Affect HealingThat Can Affect Healing

Surgical technique

Age

Edema

Disease

Muscle spasm

Wound size

InfectionNutrition

Role of Therapeutic Role of Therapeutic Exercise in Inflammation Exercise in Inflammation PhasePhase

Control edema and pain

Limit tissue stress because of weakness of fibrin plugAvoid strengthening activities

Role of Therapeutic Role of Therapeutic Exercise in Proliferation Exercise in Proliferation PhasePhase

Tissue is weak but improving in strength with collagen production.Patient can start range-of-motion and limited strengthening activities.Exception is in tendon repairs.

Role of Therapeutic Role of Therapeutic Exercise in Remodeling Exercise in Remodeling PhasePhase

Progressive increase in tensile strength allows progressive increase in stress.

Stress application must coincide with increase in tensile strength.

Considerations Considerations for Appropriate Coursefor Appropriate Course

Usual healing sequence and timing

Individual’s unique response to the injury and treatment

Signs of an Overly Signs of an Overly Aggressive ProgramAggressive Program

Increased pain, especially postexerciseIncreased edema, especially if lasts more than 1 day postexerciseDiminished function from the previous day’s treatment