Injury and the Healing Process

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Injury and the Healing Process
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Introduction to Injury

• When an injury takes place some responses are
  predictable, but others are unexpected
• It is not clear if the stages are the same in
  acute and chronic injuries
• An athletes point of view of an injury
• Painful problem that prevents or hampers sport
  performance

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Tissue Damage

• Microscopic trauma
• Involves damage to a structure at a microscopic
  level
• Macroscopic trauma
• Is obvious, visible damage to a structure
• Individual cell holds the key to the regulation
  of the bodys trauma response

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Sports Medicine Goals

• When an injury occurs the sports med team
• Minimize the adverse effects of traumatic
  inflammatory response
• Promoting tissue repair
• Expediting a safe return to performance
• Challenged to understand and anticipate the
  cellular response in predicting the recovery from
  injury

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Injury Mechanisms

• Human movement during sport and exercise is
  typically faster and or produces greater force
• As a result, the potential for injury is also
  heightened
• Understanding the different forces that act upon
  the body- you can understand how to prevent
  injuries

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Force

• Defined as a push or a pull acting on the body
• When a force is sustained by body tissue, two
  factors help determine if injury occurs
• The size and magnitude of the force
• The material properties of the involved tissues

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Magnitude of Force

• Small forces
• The response of the loaded structure is elastic
• When the load is removed the material will return
  to its original size and shape

• Large forces
• Exceeds the materials elastic limits- the
  structure is unable to elastically rebound to its
  original shape
• Some amount of deformation results

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Magnitude of Force

• Larger forces
• Exceed the materials ultimate failure limit
• Produces mechanical failure of the structure
• Translates to a bone fracture or rupturing of a
  soft tissue

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Direction

• The direction of force is applied has important
  implications for injury potential
• Many tissues are stronger in resisting force from
  some directions than from others
• Lateral ankle sprains are much more common than
  medial ankle sprains, because ligament support of
  the ankle is much stronger on the medial side

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Categories of Force

• Force acting along the long axis of a structure
  is an Axial force
• 4 categories of force
• Compression
• Tension
• Shear
• Torque

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Compressive Force

• Axial load that produces a squeezing or crushing
  effect is a compressive force
• Weight of the human body constantly produces
  compression on the bones
• When a football player is sandwiched between two
  tacklers, the force upon the player is
  compressive
• Often result in bruises or contusions

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Tensile Force

• Axial loading in the direction opposite of that
  of compression in called tension
• Pulling force that stretches the object to which
  it is applied
• Muscle contraction produces a tensile force on
  the attached bone, enabling movement
• When the ankle is inverted, the tensile force
  results in an ankle sprain

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Shear Force

• Force that acts parallel or tangent to a plane
  passing through an object
• Tends to cause one part of the object to slide,
  displace, or shear with respect to another part
  of the object

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Torque

• A rotary or twisting force is termed torque or
  torsion
• Excessive torque's can produce injury
• Usually generated by forces external to the body
  rather than by the muscles
• Torsion results in the creation of shear stress
  throughout a structure
• Causing such injuries as a spiral fracture

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Stress

• When a given force is distributed over a larger
  area, the resulting stress is less than if the
  force where distributed over a smaller area
• If a force is concentrated over a small area, the
  mechanical stress is relatively high
• Football and hockey pads- distribute any force
  sustained across the entire pad, thereby reducing
  the stress acting on the player

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Strain

• The amount of deformation an object undergoes in
  response to an applied force
• Application of a compressive force to an object
  produces shortening and widening of a structure
• Tensile force produces lengthening and narrowing
  of a structure
• Shear results in internal changes in the
  structure acted upon

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Acute vs. Chronic

• Acute Injury
• Caused by a single traumatic force
• Force is of large magnitude
• Definitive moment of onset
• Predictable process of healing
• Macrotrauma
• Ruptured ACL
• Fractured Humerus

• Chronic Injury
• Cased by repeated forces
• Force is of small magnitude
• Over a period of time
• Stress injury
• Microtrauma
• Starts when pain and inflammation become evident
• May persist for months or even years

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Bodys Response to Force

• Tendon, ligament, muscle and bone respond to
  gradually increased stress by becoming larger and
  stronger
• Overuse syndromes and stress fractures result
  from the bodys inability to adapt to an
  increased training regimen

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Soft Tissue Injuries

• Behave in characteristic ways when subjected to
  different forms of loading
• Skin
• Tendon
• Ligament
• Muscle

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Collagen

• Major building block of soft tissue
• Protein that is strong in resisting tension
• Allows tissues to stretch slightly under tensile
  loading, providing flexibility

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Skin Injuries

• Skin is the bodys first layer of defense against
  injury
• Most frequently injured body tissue
• Different Types of Skin Injuries
• Abrasions
• Blisters
• Skin Bruises
• Incision
• Laceration
• Puncture Wound

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Abrasions

• Minor skin injuries
• Caused by a shear force
• Skin is scraped with sufficient force, usually in
  one direction, against a rough surface
• The greater the applied force, the more layers of
  skin that are scraped away

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Blisters

• Minor skin injuries
• Caused by repeated application of shear in one or
  more directions
• Occurs when a shoe rubs back and forth against
  foot
• Result is the formation of a pocket of fluid
  between the multiple layers of skin

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Skin Bruises

• Contusion
• Injuries resulting from compression sustained
  during a blow
• Damage of the underlying capillaries
• Causes the accumulation of blood within the skin

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Incision and Laceration

• Incision
• Clean cut
• Produced by the application of a tensile force to
  the skin as it is stretched along a sharp edge

• Laceration
• Irregular tear in the skin
• Typically results from a combination of tension
  and shear

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Puncture Wound

• Formed when a sharp object penetrates the skin
  and underlying tissues with tensile loading
• Puncture wound can come from
• Shoe spike
• Nail

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Categories of Injury

• Muscle bruises or contusion
• Result from compression sustained from heavier
  blows
• Injuries vary in severity according to the area
  and depth over which blood vessels are ruptured
• Rated according to the extent to which associated
  joint range of motion is impaired

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Categories of Injuries

• Strain and Sprains
• Caused by an abnormally high tensile force that
  produces rupturing of the tissue and subsequent
  hemorrhage and swelling
• Categorized as first, second, and third degree
  injuries

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First Degree Injuries

• Some pain
• Only involve micro-tearing of the fibers
• No readily observable symptoms
• Mild discomfort
• Local tenderness
• Mild swelling
• Ecchymosis
• NO loss of function

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Second Degree Injury

• More severe pain
• More extensive rupturing of the tissue
• Detectable joint instability
• Muscle weakness
• Limited joint range of motion

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Third Degree Injury

• Produce severe pain
• Major loss of tissue continuity
• Loss of range of motion
• Complete instability of the joint

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Tendonitis

• Chronic condition
• Characterized by pain and swelling with tendon
  movement
• Prolonged chronic inflammation of muscle or
  tendon can result in the accumulation of mineral
  deposits, known as calcification

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Bursitis

• Involves irritation of one or more bursa, the
  fluid filled sacs
• Serve to reduce friction in the tissues
  surrounding joints
• Can be acute or chronic

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Soft Tissue Healing

• Normal healing process takes place in a regular
  and predictable fashion
• Three Phases
• Acute Response
• Repair and Regeneration
• Remodeling

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Acute Phase

• Also known as the reaction phase
• Lasts for the first several days following an
  injury
• Inflammation is major reaction in this phase
• Characteristics of the inflammatory process
• Redness, Local Heat, Swelling
• Pain and Loss of Function

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Vasoconstriction

• Vasoconstriction occurs in the acute phase
• Curtails the loss of blood
• Enables initiation of clotting
• Hypoxia and Necrosis occur due to lack of oxygen
  and blood in the area
• Hypoxia
• Reduced oxygen in tissue
• Necrosis
• Death of tissue

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Vasodilatation

• Vasodilatation also occurs in the acute phase
• Occurs after vasoconstriction
• Brought on by chemicals released by the body
• Increased blood flow causes swelling in area of
  injury
• Broken blood vessels and damaged cells form a
  hematoma
• Speeds the arrival of specialized cells that will
  ingest dead cells and any foreign material or
  infectious agents
• The resulting swelling also stimulates nerve
  endings to cause pain

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Repair and Regeneration Phase

• Takes place from about 2 days following the
  injury through the next 6-8 weeks
• Begins when hematoma has diminished in size
  allowing room for growth of new tissue
• Except for skin, all other soft tissues replace
  damaged cells with scar tissue
• Healing begins with the accumulation of
  fibroblasts to produce scar tissue

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Repair and Regeneration Phase Cont

• Fibroblasts begin to produce immature collagen
• The scar tissue that is formed is less strong and
  less functional than the original tissue
• Development of the scar also causes the wound to
  shrink in size, resulting in decreased
  flexibility of the affected tissue

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Remodeling Phase

• Begins about 3 weeks post injury, overlapping the
  repair and regeneration phase and continues for a
  year or more
• Maturation of the newly formed tissue
• Decreased fibroblast activity
• Organization of the tissues increases and normal
  chemical activity resumes

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Severe Muscle Injuries

• Severe muscle injuries can result in scarring or
  the formation of adhesions
• After severe injury, muscle may regain only about
  50 of its pre-injury strength
• Adhesions
• Tissues that bind the healing tissue to adjacent
  structures
• Happens within the muscle
• Inhibits muscle fiber regeneration

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Tendon and ligament injuries

• Have few reparative cells
• Healing may take more than a year
• If these tissues undergo abnormally high tensile
  stress before scar formation is complete, the
  newly formed tissues can be elongated
• This may result in permanent joint instability

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Bone Injury Healing

• Three Phases Process
• Acute Phase
• Repair and Regeneration
• Remodeling Phase

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Acute Phase

• Last approximately 4 days
• Hematoma is formed
• Vasodilatation occurs
• Edema
• Tissue chemical changes

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Repair and Regeneration Phase

• Osteoclasts come to the area of injury to
  reabsorb damaged bone tissue
• Osteoblasts build new bone
• A callus is forms between the fractured bone ends
• A callus is a fibrous vascularized tissue
  containing immature bone
• Strengthens with time through remodeling phase
• Fixation devices are only implanted when it
  appears unlikely that the fracture will not heal
  properly

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Remodeling Phase

• Osteoblasts and Osteoclasts activity continues
  until normal shape and strength has restored
• Time is the largest requirement for proper none
  union to take place
• Complete remodeling may take many years

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Nerve Injuries

• Most commonly injured by tensile or compressive
  forces
• When a nerve is loaded with tension, the nerve
  fibers tend to rupture prior to the rupturing of
  the surrounding tissue
• The nerve roots on the spinal cord are not
  protected by connective tissue and are
  particularly susceptible to tensile injury,
  especially stretching of the brachial and
  cervical plexus

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Compression Injury to Nerves

• More complex
• Severity depends on the magnitude and duration of
  the loading force
• Nerve function is highly dependent on oxygen
  provided by blood vessels
• Damage to the blood supply caused by a
  compressive injury results in damage to the nerve

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Nerve Injuries

• Symptoms can range
• Pain
• Discomfort
• Complete loss of sensation
• Chronic irritation/inflammation
• Lead to chronic pain along the nerves path
• Pinching of a nerve
• Results in a sharp wave of pain that is
  transmitted through a body segment

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Nerve Healing

• Completely severed nerve
• Healing does not occur
• Loss of function is typically permanent
• Incomplete nerve injury
• Sometimes possible for regeneration
• Regeneration is relatively slow

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Pain

• Universal Symptom common to most injuries
• Individuals perception of pain is influenced by
  four factors
• Physical
• Chemical
• Social
• Psychological

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Neurological Basis of Pain

• Small diameter, slow transmission nerves carry
  pain impulses
• Fast transmission nerves carry other sensations
  touch, temperature, proprioception
• Located in superficial skin layers
• Can be stimulated by mechanical stresses such as
  trauma, swelling, and muscle spasm
• Other pain receptors are chemo-sensitive
• Pain threshold can become progressively lower

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Gate Control Theory

• Spinal cord is organized in such a way that pain
  or other sensations may be experienced
• An area or gate within the spinal cord
  organizes input stimulus and transmits stimulus
  to the brain
• Therefore, stimulation from the larger, faster
  nerves can selectively close the gate to the
  smaller, slower pain fibers
• Concept explains why cold can numb the pain as
  well as why acupuncture, acupressure and skin
  irritants provide some relief against pain

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Factors That Mediate Pain

• Body produces natural pain killers that are
  chemicals similar to morphine called endorphins
• Endorphins block nerve receptors sites that
  transmit pain
• Pain is a mixture of physiological and
  psychological factors
• Individuals vary in their pain thresholds

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Referred Pain

• Pain that is perceived at a location remote from
  the injury site
• Pain is thought of as an error in perception on
  the part of the brain and body
• Some referred pain is predictable
• Heart attack-left shoulder and arm
• Spleen- left shoulder/arm

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Nutrition and Healing

• Proper nutrition is essential to provide the
  necessary nutrients for wound healing
• Proteins
• Vital role in repair, growth and maintenance of
  body tissue
• Carbohydrates
• Main energy fuel for the body and important for
  repair and healing

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Nutrition and Healing

• Vitamins
• Important role in wound healing
• Vitamin B, C, A,E, and K are all important
• Supplements
• Are not necessary for healing as long as athlete
  diet is nutritionally balanced

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The End

• Any Questions??