Ch. 2

Tissue Healing

Introduction

• Tissue healing occurs and is influenced by several factors

• There are three phases:– Inflammatory response– Repair/regeneration– remodeling

Inflammatory Response

• Cells remove debris• Cells create groundwork for repair and

regeneration phase

Repair/Regeneration Phase

• Cells restore the vascular and structural integrity of injured structures

Remodeling Phase

• Healed tissue adapts to functional loading• Gets stronger based on the stress that is

applied to it• The three phases overlap one another• Disruption of any one phase can cause an

unsatisfactory outcome

Types of Tissue

• Epithelial tissue• Connective• Muscle • nervous

Epithelial Tissue

• Composed of layers of cells• Protect organs• Secretions (glands)• Absorption ( lining of the stomach )

Connective Tissue

• Most abundant and variable tissue in the body• Attaching organs• Support/structure• Movement • Physical protection• Immune response, energy & mineral storage• Heat generation and transportation (blood,

etc.)

Connective Tissue

• Subtypes:– Fluid connective tissue=blood and lymph– Fibroconnective tissue=fat, tendons and ligaments– Supportive connective tissue=cartilage and bone

Nervous Tissue

• Located in brain and spinal cord and nerves• Electrically exciteable• Used to transmit and respond to various

impulses and forms of information

Muscle Tissue

• Skeletal- striated or voluntary• Cardiac – heart muscle• Smooth- linings of organs and blood vessels

Common Injuries

Puncture and Laceration

Incision

Acute vs. Chronic

• Acute – single forcefull event (ACL tear)• Chronic – occur over a period of time (Tennis

elbow)

Acute Injuries

• Contusions – bruises• Strains – muscle or tendon injuries• Sprains – ligamentous injuries

Contusions

• Caused by compressive forces• or direct impacts and are graded by degrees

of trauma• 1st degree-minimal swelling, no limits• 2nd – pain, bleeding, moderate functional

limits• 3rd-hematoma formation,sever limitations

Sprains and Strains

Fracture Classifications

• Greenstick• Transverse• Oblique• Spiral• Comminuted• Avulsion• Impacted• Depressed• Epiphyseal (Salter-Harris classification)

Peripheral Nerve Injuries

• Neuropraxia-least severe, transient and reversible loss of nerve function

• Axontomesis- partial disruption, may cause atrophy or weakness for 2 – 52 weeks

• Neurotomesis – complete severance of a nerve resulting in permanent loss of function

Chronic Injuries

• Blisters – continuous friction• Repetitive overload – tendinosis, tenosynovitis• Chronic irritation –could cause neuralgia or

neuroma

Soft Tissue Healing

• Phase 1: Inflammatory Response• Phase 2: Repair/Regeneration• Phase 3: Remodeling/Maturation

Phase 1

• Signs and symptoms:– Redness– Heat– Pain – Swelling– Loss of function

Phase 1 con’t

• Lasts 7-10 days• Initial damage is called “the primary injury”• Caused by a release of proteins at the injury site• Mast cells produce chemicals (histamines)

which promote vasodilation• This causes the redness and heat• Vessels become more permeable which

contributes to the swelling

Phase 1

• Mast cells also release chemicals that attract neutrophils (immune cells) to come to the injury

• Neutrophils clear debris and regulate the early inflammatory process

• Injured area becomes ischemic and acidic which may cause secondary damage to otherwise healthy areas around the injury

Phase 1

• Neutrophils die and are ingested by macrophages at the injury site

• When this happens the macrophages begin to produce proteins that promote tissue repair

• Early scar tissue forms• Early rehab should focus on pain

management, decreasing swelling, promote tissue healing

Phase 1

• Immobilization or protection should be done• RICE• NSAIDS for decreased inflammatory symptoms• Short term analgesic

Phase 2: Repair/Regeneration

• Repair- articular cartilage, meniscus, spinal cord (new tissue is not identical)

• Regeneration- bone, muscle, peripheral nerve, blood vessels (heal with identical tissue)

• Patients are still swollen and pain with motion• Blends with the inflammatory phase and

remodeling phase• Day 7 to 21

Phase 2

• Fibrin clots form• Fibroblasts proliferate near the injury• Capillary proliferation occurs (more oxygen

needed)• Fibroblasts produce fibronectin, collagens,

glycoproteins• Fibronectin begins dormant followed by type

III collagen then to stronger type I

Phase 2

• Initially patient has structural deficiency• Treatment – early controlled mobilization• This aligns collagen with areas of physical

stress making it stronger• Prevents atrophy

Phase 3: Remodeling/Maturation

• Lasts up to 24 months• May have persistent swelling and pain with

motion• Fibroblast activity decreases throughout this

phase• Capillary density decreases• Cellular matrix becomes more refined

Phase 3

• More type I and type III collagen fibers are produced

• Tensile strength improves• Rehab can increase the physical demands until

patients return to their activities of daily living

Fracture Healing

• Four phases:– Inflammation– Soft callus formation– Hard callus formation– Bone remodeling

Phase 1: Acute

• Lasts up to a week• Hematoma formation, inflammation,

angiogenesis (new blood vessel formation), soft callus formation

• Dominated by immune cells• Phagocytic cells remove debris• Platelets form clots

Phase 2: Repair/Regeneration

• Lasts 8 to 12 weeks• Remodeling of scar tissue through cartilage

formation, calcification and bone formation• Mesenchymal cells become cartilage cells• Proliferate the soft callus• Replace the scar tissue with cartilage• Chondrycytes hypertrophy and release

chemicals to promote bone formation

Phase 2

• Osteoblasts produce new bone• Revascularization of the region occurs• Soft tissue is replaced by bone• Casting is used to allow time for a proper

callus to develop

Phase 3: Remodeling

• Starts during Phase 2 and continues for several years

• Starts 21 days post fracture• Woven bone replaced by cortical or trabecular

bone• New bone is remodeled by osteoclasts and

osteoblasts based on mechanical loading

Fracture Management

• Treatment varies by :• type of fixation– No reduction– Closed reduction– Open reduction– Open reduction internal fixation (ORIF)

• Location of fx• Involved bone• Mechanical loads• Surrounding soft tissue

Fracture Management

• ORIF – Surgical fixation– Uses metal implants to stabilize fx’s– May allow rehab to begin within first week after

surgery ( edema control, wound management, early motion)

– More aggressive rehab can begin in 6-8 weeks

Fracture Management

• Non-surgical fixation– ROM delayed for 3 weeks– Until callus has enough tensile strength to tolerate

movement– At 6-8 weeks patient may begin strengthening

exercises and increase mechanical loads– Upper extremity fx’s may begin ROM exercises

sooner because of smaller loads and fear of atrophy

Delayed/Non Union Fx’s

• Causes– Nutritional deficiencies– Diabetes, anemia– Smoking– Pharmacological drug use– Pre-injury vascular status– Muscle around fracture– Inadequate immobilization– Infection– High energy fractures– Gap distance– Nerve injury

Delayed / Non Union Fx’s

• Susceptible areas– Tibia– Ulna– Femoral neck– Scaphoid (most common)

Peripheral Nervous Healing

• More proximal injuries result in greater losses• Within 3 -5 days, axons distal to the injury

undergo a degenerative process called Wallerian degeneration

• This is promote by immune cells, Schwann cells(the cell that normally myelinate axons) and the distal axon

Nerve Healing

• Produce proteins that produce and inflammatory response and pain

• Schwann cells divide to create an optimal environment for regeneration

• Surgical repairs can be helpful but are not guaranteed

• Only one proximal branch will form a new axon the others will degenerate

Muscle Healing

• Tissue trauma• Hematoma formation• Inflammatory cell reaction • Phagocytosis• Capillary regrowth• Scar formation• remodeling

Muscle Healing

• Must balance regeneration with scar formation• Scar tissue is weak and only serves as a

“scaffold” for the healing process• Site is still weak • No active motion immediately after injury• Could result in re-rupture• However, prolonged immobilization could result

in atrophy

Muscle Healing

• What do you do?

Muscle Healing

• Early mobilization and motion may be started within the first 24 hours

• It must be pain free to avoid overloading• Pain is your guide

Tendon Healing

• Ruptured tendons often require surgery• Once repaired the tendon ends can go

through their normal healing stages

Tendon Healing

• Hematoma formation• Platelet aggregation• Recruitment of inflammatory cells• Phagocytosis• Angiogenesis• Fibroblast proliferation• remodeling

Tendon Healing

• Tensile strength increases at 4 weeks• Continues to improve up to 1 year• Strength of tendon never returns to pre-injury

level

Factors Affecting Healing

• Healing process is variable• Factors:– Extensive trauma– Blood supply– Infection– Diabetes– Age – nutrition

Critical Thinking

• In a rehab setting, patients want to return ASAP. As a result, some patients do extra exercises, stretch to a point of pain, or try aggressive exercises (e.g. running) too early. What are the potential hazards to this approach? How would you explain your concerns to the patient or athlete?

Critical Thinking

• Two patients that are 10 weeks post –fractures are exercising next to each other. One of the patients had a distal radius fracture and the other had a scaphoid fracture. Both were treated conservatively with immobilization. The patient with the scaphoid fracture notices that she is still not able to do a lot of the exercises her counterpart is able to perform. She then asks why she is not progressing at the same rate as the other patient. How would you explain the differences in their recovery?