Tissue Healing and Wound Care
Chapter 6
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Force and Its Effects
• Two potential effects of force:
– Acceleration
– Deformation
• Factors that determine injury
– Magnitude of force
– Material properties of tissues involved
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Response to Force
• Small load - elastic response
– Load is removed, material returns to its original shape
• Load reaching yield point - plastic response
– Load is removed, some amount of deformation
remains
• Yield load
– Maximum load a material can handle without
permanent deformation
• Failure
– Force such as loss of continuity, rupturing soft tissue
or fracturing bone
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Direction of Force
• Many tissues are anisotropic
– Different strengths in response to loads from
different directions
• Anatomic make-up of joint
– Susceptibility from a given direction
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Categorize Force Relative to Direction
• Axial
–
Force that acts on the long axis of a structure
• Compression
–
Axial load that produces a crushing or squeezing type
force
• Tension
–
Axial force in opposite direction; pulling or stretching
the tissues
• Shear
–
Force parallel to a plane passing through the object
–
Tends to cause sliding or displacement
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Categorize Force Relative to Direction
(cont.)
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Magnitude of Stress
• Stress
– Force divided by the
area over which the
force acts
• A given force over a large
area vs. a small
concentrated area can
have very different results
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Strain vs. Force
• Strain
– The amount of deformation relative to the original
size of the structure
– Result
• Compression - shortening and widening
• Tension - lengthening and narrowing
• Shear - internal deformation
• Problem: high strain rather than high force
• The ability to resist strain relative to strength of tissues
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Element of Time
• Acute injury
– Results from a single force
– Causative factor - macrotrauma
– Characterized by a definitive moment of onset
• Chronic or stress injury
– Results from repeated loading
– Causative factor - microtrauma
– Characterized by becoming more problematic over
time
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Positive Stress vs. Adverse Stress
• gradual mechanical stress
size & strength
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Torque
• Moment arm
– Perpendicular distance
from force line of
action to the axis of
rotation
• Torque
– Force × moment arm
– Produces rotation of a
body
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Torque (cont.)
• Injury potential
–
Bending
• Tension on one side of
object and compression
on the other side
–
Torsion
• Twisting an object's
longitudinal axis
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Soft Tissue – Anatomic Properties
• Collagen
–
Primary constituent of
skin, tendon, ligaments
–
Protein substance strong
in resisting tensile forces
–
Wavy configuration that
allows for an elastic type
deformation or stretch
but, otherwise, is inelastic
• Elastin
–
Protein substance
–
Adds elasticity
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Skin
• Epidermis
• Dermis
– Multidirectional
arrangement of
collagen
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Tendons
• Muscle to bone
• Dense connective tissue with
unidirectional bundles of
collagen and some elastin
• Collagen - parallel arrangement
–
Helps in resisting high,
unidirectional tension
loads from the attached
muscle
• Two times as strong as muscle
it serves
–
Yield point 5-8% in length
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Aponeuroses
• Attach muscle to other muscles or bone
• Dense connective tissue
• Strong, flat, sheet-like
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Muscle
• Viscoelastic
– Extensibility - ability to be
stretched
– Elasticity - ability to return to
normal length
• Viscoelasticity allows muscle to
stretch to greater lengths over
time in response to a sustained
tensile force
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Muscle (cont.)
• Irritability - ability to respond to a stimulus
– Electrochemical - nerve impulse
– Mechanical - external blow
• Contractility - ability to develop tension
– Isometric
– Concentric
– Eccentric
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Joint Capsule
• Membrane that encloses a joint; composed primarily of
collagen
• Function: hold bones in place
• Inner lining: synovial membrane
– Exit for waste; entrance for nutrients
– Secretes synovial fluid (lubricates and nourishes)
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Ligaments
• Bone to bone
• Collagen is parallel and
interwoven
–
Resists large tensile loads
along the long axis of the
ligament and smaller
loads from other
directions
• Collagen and elastin intermixed
(more elastic than tendons)
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Bursa
• Fluid-filled sacs
• Reduce friction
• Common sites – areas of friction
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Classification of Joints
• Fibrous (synarthrosis)
– Held together by fibrous tissue
– Can absorb shock but permits little or no
movement of the articulating bones
– Example: sutures in the skull
– Syndesmoses
• Joined by dense fibrous tissue
• Permit extremely limited motion
• Example: interosseous membrane
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Classification of Joints (cont.)
• Cartilaginous (amphiarthroses)
– Primary
• Held together by hyaline cartilage
• Example: sternocostal joints; epiphyseal plates
• Can absorb shock, but permits little or no
movement
– Secondary
• Held together by fibrocartilage
• Movement of the articulating bones
• Designed for strength and shock absorption
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Classification of Joints (cont.)
• Synovial (diarthroses)
– Freely movable joints
– Classified according to their shape – dictates type
and range of motion permitted
• Plane
• Hinge
• Pivot
• Condyloid
• Saddle
• Ball and socket
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Classification of Joints (cont.)
• Synovial joint
– Articular cartilage
• Covers ends of long
bones, cushion and
protection, no nerve or
blood supply
– Joint cavity
• Filled with synovial
fluid
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Classification of Joints (cont.)
– Articular capsule
• Joint capsule
– Synovial fluid
• Reduces friction
– Ligaments
• Capsular, extracapsular
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Skin Injury Classifications
• Abrasions
– Scraping away of layers of skin
• Blisters
– Accumulation of fluid between epidermis
and dermis
• Skin bruises
– Accumulation of blood within skin
• Incisions
– Clean cut
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Skin Injury Classifications (cont.)
• Lacerations
– Irregular tear
• Avulsions
– Complete separation of skin
• Punctures
– Penetration of skin and underlying tissue
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Classification of Muscle/ Tendon Injuries
Contusion
• Mechanism: compression
• Signs and symptoms (S&S)
– Onset - acute
– Pain - localized
– Ecchymosis: if superficial
– Restrictions in ROM
– Swelling
– Associated nerve compression
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Contusion (cont.)
• Basis for rating severity – ROM
– 1st – little or no restriction
– 2nd – noticeable reduction
– 3rd – severe restriction
• Concern: can lead to muscle strain
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Strain
• Stretch or tear of a muscle
• Mechanism: tension force
• Most common site for tears: near the
musculotendinous junction
• Key factor: magnitude of force and structure's
cross-sectional area
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Classification of Strains
1st
2nd
3rd
damage to fibers
few fibers torn
nearly half torn
all fibers torn
weakness
mild
moderate (reflex
inhibition)
severe
muscle spasm
mild
moderate
severe
loss of function
mild
moderate
severe (reflex
inhibition)
swelling
mild
moderate
severe
palpable defect
no
no
yes (if early)
pain-contraction
mild
moderate /severe
none/mild
pain-stretching
yes
yes
no
ROM
decreased
decreased
depends on swelling
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Cramps and Sprains
• Involuntary muscle contraction
• Cramp
– Biochemical imbalance, fatigue
– Types
• Clonic - alternating contraction/relaxation
• Tonic - constant
• Spasm
– Reflex action due to:
• Biochemical or
• Mechanical blow to nerve or muscle
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Myositis and Fasciitis
• Myositis
– Inflammation of connective tissue
• Fasciitis
– Inflammation of the fascia surrounding portions
of a muscle
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Tendinitis and Tenosynovitis
• Tendinitis
– Inflammation of tendon
– Pain and swelling with tendon movement
– Problems - repeated microtrauma
• Degenerative changes
• Tenosynovitis
– Inflammation of synovial sheath
– S&S
• Acute: rapid onset, crepitus, local swelling
• Chronic: thickened tendon, nodule formation in
sheath
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Myositis Ossificans
• Ectopic calcification - located in place other than
normal
• Bone (calcium) is deposited within a muscle
• Usually macrotrauma, but can be microtrauma
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Chronic Conditions
• Result of repeated irritation of tissues
• Classification
– Stage 1: pain after activity only
– Stage 2: pain during activity, does not restrict
performance
– Stage 3: pain during activity, restricts performance
– Stage 4: chronic unremitting pain, even at rest
• Problem – low-grade inflammatory condition that results in
collagen resorption and scarring
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Joint Injury Classifications
Sprain
• Stretch or tear of ligament
• Mechanism of injury (MOI) – tension force
• Compromises the ability of the ligament to
stabilize the joint
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Classification of Sprains
1st
2nd
3rd
damage to ligament
few fibers torn
nearly half torn
all fibers torn
distraction stress
<5 mm
5-10 mm
>10 mm
weakness
mild
moderate/severe
moderate/severe
muscle spasm
none
none/minor
none/minor
loss of function
mild
moderate/severe
severe
swelling
mild
moderate
moderate/severe
pain-contraction
none
none
none
pain-stretching
yes
yes
no
ROM
decreased
decreased
increase or decrease
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Dislocation/Subluxation
• Joint force beyond normal limits
• MOI: tension
• S&S
– Loss of limb function
– Deformity
– Swelling
– Point tenderness
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Dislocation/Subluxation
• Problem of reoccurrence
– Due to overstretching of capsule to the extent
that it will not return to normal; unstable joint
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Bursitis
• Inflammation of bursa
• Acute or chronic
• MOI: compression
• S&S: swelling, pain, loss of function, eventual
degeneration
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Osteoarthritis
• Degeneration of articular cartilage
• S&S: pain and limited movement
• No definitive cause; rather, several contributing
factors
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Soft Tissue Healing
• Inflammatory phase (0-6 days)
– Acute or chronic inflammation possible
– Exudate forms
– Mechanisms for stopping blood flow
• Local vasoconstriction
• Platelet reaction
• Coagulation cascade
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Soft Tissue Healing (cont.)
– Vasodilation brings neutrophils and macrophages to clean
the area via phagocytosis
– Mast cells release
• Heparin: thins the blood and prolongs clotting
• Histamine: promotes further vasodilation
• Bradykinin: opens the blood vessel walls; causes pain
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Soft Tissue Healing (cont.)
• Inflammatory phase (cont.)
– Zone of primary injury
• Hematoma forms
– Edema occurs
• Increased permeability and pressure within
the vessels forces a plasma exudate into
the interstitial tissue
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Soft Tissue Healing (cont.)
– Zone of secondary injury
• Interstitial tissues affected by
inflammation, edema, and hypoxia
• Prostaglandins promote further healing
and clearing of debris
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Soft Tissue Healing (cont.)
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Soft Tissue Healing (cont.)
• Proliferative phase (3-42 days)
– Repair and regeneration of tissue
– Processes
• Angiogenesis
• Fibroplasia
• Re-epithelialization
• Wound contraction
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Soft Tissue Healing (cont.)
– Hematoma reduces for new healing to take place
– Scar formation with soft tissue
– Accumulated exudate contains fibroblasts that generate
new collagen
– Newly formed blood supply and support of matrix will
determine overall healing of new tissue
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Soft Tissue Healing (cont.)
• Maturation phase (3 weeks – 1 year)
– Associated processes
– Remodeling of fibrous matrix to form mature scar tissue
• Decreased fibroblastic activity
• Increased organization of new tissue
• Decreased water content
• Decreased blood flow
• Resumption of normal cell activity in the area
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Soft Tissue Healing (cont.)
– Scar tissue is fibrous, inelastic, and nonvascular
• Less functional and flexible than original tissues
• Tensile strength
 3-4 weeks – 25% of normal
 4-5 months – 30% below preinjury strength
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Soft Tissue Healing (cont.)
• Maturation phase (cont.)
– Muscle fibers form adhesions
– Tendons and ligaments slower to heal
– Potential for atrophy with immobilization
– Loss of strength and decreased rates of healing
are directly related to length of immobilization
– Begin strengthening as soon as it’s safe after
injury to ensure hypertrophy of healing tissues
and decreased reoccurrence of injury
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Soft Tissue Wound Care
• Open wound
– Follow universal precautions and infection control
standards
– General
• Apply pressure
• Cleanse the wound
• Dress and bandage the wound
• Use of creams or ointments
• Re-dress and inspect
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Soft Tissue Wound Care (cont.)
• Closed wound
– Goal: reduce inflammation, pain, and secondary
hypoxia
– Treatment: ice, compression, and elevation
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Long Bones – Anatomic Properties
• Primary constituents:
minerals, collagen, water
• Components
– Diaphysis
• Shaft - hollow,
cylindrical
• Medullary cavity shock potential
improves
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Long Bones – Anatomic Properties (cont.)
– Epiphysis
• Ends of long bones
• Epiphyseal plate - cartilaginous disc found
near ends of long bones
– Periosteum
• Sheath covers bone
• Life support system
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Long Bones – Anatomic Properties (cont.)
• Bone growth
– Longitudinal
• Continues until
epiphysis closes
– Diameter
• Can continue to grow
through the lifespan
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Long Bones – Anatomic Properties (cont.)
• New bone formed via the periosteum; bone is resorbed around
the medullary cavity
– Osteoblasts – form new bone
– Osteoclasts – resorb bone
• Bone experiences constant remodeling
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Internal Composition: Long Bones – Anatomic
Properties (cont.)
• Cortical
• Cancellous
– Compact bone tissue
of high density (low
porosity)
– Outside
– Can withstand
greater stress but
less strain
– Bone tissue of low
density (high porosity)
– Inside
– Can tolerate more
strain
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Long Bones – Anatomic Properties (cont.)
• Size will increase in response to increased stress
(conditioning)
• Hollow cylinder - strongest structure in resisting
tension and compression
• Anatomic weakness - site where bone changes shape
and direction (especially sudden change)
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Mechanical Forces Affecting Bones
• Tension, compression, shear, bending,
torsion
• Stronger in resisting compression than
both tension and shear
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Classification of Bone Injuries
Fractures
• Disruption in the continuity of bone
– Closed or open
• Type of fracture determined by:
– Force applied
– The health and maturity of bone at the
time of injury
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Types of Fractures
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Stress Fracture
• Stress fracture
– Fracture results from repeated loading with
lower magnitude forces
– Can become worse over time
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Osteopenia
• Osteopenia
– Reduced bone mineral density that
predisposes individual to fracture
– Possible causes: amenorrhea, hormonal
factors, dietary insufficiencies
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Epiphyseal Injuries
• Injury to growth plate could
result in alteration in normal
growth
• Acute injury
– Types I-V
• Osteochondrosis
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Epiphyseal Injuries (cont.)
• Osteochondrosis
– Disruption of blood supply to epiphysis
– Idiopathic
– Example: Legg-Calvé-Perthes disease
• Apophysitis
– Osteochondrosis of apophysis
– Example:
• Sever’s disease
• Osgood-Schlatter disease
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Bony Tissue Healing
• Acute inflammatory phase
– Formation of hematoma
– Inflammatory response
• Proliferative phase
– Osteoclasts – resorb damaged tissue; osteoblasts –
deposit new bone
– Callus formation
• Maturation phase
– Continued activity of osteoclasts and osteoblasts
– Remodeling of bone
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Bony Tissue Healing (cont.)
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Bony Tissue Healing (cont.)
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Bony Tissue Healing (cont.)
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Bone Injury Management
• Fracture detection
– Palpation, percussion, tuning fork, compression,
distraction
• Management – splinting (refer to Application Strategy
6.3)
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Nerve – Anatomic Properties
• Spinal nerve
– Roots
• Posterior – afferent
• Anterior – efferent
– Heavily vascularized
– Myelin sheath
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Spinal Nerves
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Classification of Nerve Injuries
• Tensile force injuries
– Neurapraxia (grade 1)
• Localized conduction block: temporary loss of
sensation and/or motor
• Resolves within days to a few weeks
– Axonotmesis (grade 2)
• Significant motor and mild sensory deficits
• Lasts at least 2 weeks
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Classification of Nerve Injuries (cont.)
– Neurotmesis (grade 3)
• Motor and sensory deficit
• Lasts up to 1 year
• Compressive injuries
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Classification of Nerve Injuries (cont.)
• Nerve injuries result in a variety of afferent symptoms
– Hyperesthesia
– Hypoesthesia
– Paresthesia
• Neuralgia
– Chronic pain along nerve’s course
• Healing: if completely severed, healing does not occur
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Management of Nerve Injuries
• Mild – follow acute care protocol
• Moderate to severe – physician referral
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Pain
• Sources
– Somatic, visceral, and psychogenic
• Nociceptors
– Mechanosensitive
– Chemosensitive
• Fibers transmitting pain
– A fibers
– C fibers
– T cells
• Gate control theory of pain
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Pain (cont.)
• Factors than mediate pain
– Brain production of opioid peptides and endorphins
– Cognitive and affective filters
• Referred pain
– Pain perceived at a location remote from the site
actually causing the pain
• Radiating pain
– Pain felt both at its source and along a nerve
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