The Injury Process

1
Chapter 8

• The Injury Process

2
The Physics of Sports Injury

• Tissues of the body
• connective tissues are most common, i.e..,
  ligament, capsule, tendon, etc.
• other types of tissues include epithelial,
  muscle, and nerve.
• 50 of acute injuries involve either muscle or
  tendon.

3
The Physics of Sports Injury

• Muscle/tendon injuries
• injured by excessive tension
• muscle/fascia injuries occur during eccentric
  contraction
• tendons are strong -- 8700 to 18,000 lb./sq.
  inch.
• strains occur most often at the MTJ
• musculotendinous strains -- most common soft
  tissue sports injuries

4
Related Injuries in the Adolescent

• Growth plates (epiphysis) and injury potential
• In the child, attachments of ligaments, capsule,
  and tendons are often stronger than the growth
  plate.

5
Related Injuries in the Adolescent

• Simple strains and sprains can be more serious
  since a growth plate may be involved.
• If a child sustains an injury around a joint with
  extreme pain, swelling or deformity -- refer to a
  medical doctor.
• Such injuries are most common in the elbow, knee
  and hip.

6
Mechanical Forces of Injury
Compressive

• Three types of force
• tensile, compressive, shear

Tension
Shear
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Mechanical Forces of Injury

• tendons resist tensile force
• bones resist compressive force
• ligaments resists tensile force

8
Critical Force

• Critical force varies for each type of tissue
• Critical force may vary within the same tissue,
  depending upon
• age
• temperature
• skeletal maturity
• gender
• body weight

9
The Physiology of Sports Injury

• The inflammatory process
• Whenever damaged, the body reacts with a
  predictable sequence of physiologic actions,
  commonly called swelling.
• begins during the first few minutes following an
  injury

10
The Physiology of Sports Injury

• Normal signs/symptoms include swelling, pain,
  reddening of skin (erythema), and increased local
  temperature.
• several specific stages
• acute
• resolution
• regeneration
• repair

11
Acute Inflammatory Phase

• Trauma destroys millions of cells.
• Vasoconstriction is followed by vasodilation.
• Vasodilation results in blood flow into
  interstitial spaces resulting in hematoma.
• Hematoma is localized collection of extravasted
  blood.
• Secondary hypoxic injury results in additional
  destruction.

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Acute Inflammatory Phase

• Lysosomes release powerful chemicals.
• Three groups of chemicals --
• degradative (cellular breakdown)
• vasoactive (vasodilators)
• chemotactic (attracting cells)

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Acute Inflammatory Phase (continued)

• Hageman Factor -- manufacture of bradykinin
• Bradykinin increases vascular permiability.
• Bradykinin triggers release of prostaglandins
  resulting in
• vasodilation
• increased vascular permeability
• pain and fever
• blood clotting

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Acute Inflammatory Phase (continued)

• Plasma proteins, platelets and leukocytes pass
  out of capillaries.
• Leukocytes engage in phagocytosis.
• Macrophages migrate into the damaged area.

• Arachidonic acid is formed by a combination of
  leukocyte enzymes and phospholipids derived from
  cell membranes.

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Acute Inflammatory Phase (continued)

• Arachidonic acid -- a catalyst for a variety of
  inflammatory substances
• This phase results in a walling off of damaged
  area -- a necessary component for healing.
• Neutrophils arrive within 7 hrs. They are
  short-lived but they attract macrophages.
• Macrophages can reproduce and live for months.
  They consume cellular debris by way of
  phagocytosis.

16
Resolution (Healing) Phase

• No additional trauma -- acute inflammatory phase
  lasts up to 3-4 days.
• During this phase, special cells migrate into the
  area of injury polymorphs, monocytes and
  histocytes
• All of these cells serve to breakdown cellular
  debris.

17
Regeneration and Repair

• Except for bone, tissues heal with scar tissue
  that begins to form 3-4 days after the injury.
• Fibroblasts (fiber producing cells) migrate into
  damaged area.
• Fibroblasts can mature into several types of
  cells.
• Fibroblasts produce collagen fibers and
  proteoglycans.

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Regeneration and Repair

• Angiogenesis -- forming new capillaries
• Scar formation may take fours months -- scar can
  be 95 as strong as original tissue.

• Stress is helpful -- rehabilitation exercises are
  critical to this process.
• Bone tissue heals by way of specialized cells
  osteoclasts.

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Regeneration and Repair (continued)

• Specialized fibroblasts (osteoblasts) migrate
  into the area.
• Osteoblasts develop a zone of collagen known as a
  callus (seen at right in the X-ray). The
  callus fills the area of fracture.

20
Intervention Procedures

• Controlling the inflammatory process
• sports medicine community -- no concise protocol
  for the treatment of acute, soft tissue injury
• cryotherapy (crushed ice bags, aerosol coolants,
  ice cups, ice water baths, commercial cold packs)
• After the acute phase, application of heat is
  appropriate (hydrocolator packs, warm towels, and
  ultrasound).

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Intervention Procedure

• Modalities such as ultrasound should ONLY be used
  by appropriately trained allied health personnel.
• Pharmacologic agents can be used, such as
  anti-inflammatories and analgesics.
• If prescribed by a physician, as such, represent
  a treatment beyond the scope of coach.
• OTC drugs should also be used with caution.

22
Cryotherapy and Therapy

• Direct application of cold results in
  vasoconstriction during the first few minutes.
• Immediate application of cold reduces the
  severity of the secondary hypoxic injury.

23
Cryotherapy and Therapy

• In extremities, elevation and compression are
  helpful.
• I.C.E. -- ice, compression and elevation
• Crushed ice in a sandwich bag is an inexpensive
  technique.
• Cold application -- decreases the recovery time
  by lowering the oxygen equirement of the tissue
• Cold application -- analgesic effect

24
Cryotherapy and Therapy

• Research shows thermotherapeutic agents should
  NEVER be applied to an acute injury.
• Thermotherapies are useful in the final stages of
  injury repair.

• Elastic wraps work well to secure the bag to the
  body.
• Recommended protocol -- apply for 30 minutes,
  remove for 2 hours, and re-apply for another 30
  minutes

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Cryotherapy and Thermotherapy (continued)

• Risk of frostbite from a bag of crushed ice is
  minimal -- human tissue freezes at approx. 25
  degrees F (ice bag reaches a low of 32 degrees F).

26
Pharmacologic Agents

• Steroidal and non-steroidal anti-inflammatory
  drugs (NSAID)
• Both groups interfere with the inflammatory
  process.
• Steroidal drugs resemble gluococorticoids --
  exact mechanism unknown
• Side effects of steroids include interfering with
  collagen formation.

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Pharmacologic Agents

• Steroids may
• decrease permeability of capillaries
• decrease amount of chemicals released by
  lysosomes
• reduce effectiveness of WBCs in phagocytosis
• reduce local fever

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Pharmacologic Agents

• Steroids may be injected or taken orally and
  include drugs like
• cortisone, hydrocortisone, prednisone,
  prednisolone, triamcinolone, dexamethasone
• NSAIDs are very popular drugs with 1.3 million
  subscriptions in 1991
• Common NSAIDs include drugs such as, aspirin,
  ibuprofen, naproxen, indomethacin, sulindac,
  naproxen sodium

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Pharmacologic Agents (continued)

• NSAIDs have no effect on connective tissues
• As a group, NSAIDs block the breakdown of
  arachidonic acid to prostaglandins.
• Some NSAIDs also function as analgesics.
• Research is inconclusive regarding NSAIDs effect
  on healing.
• Best approach to care of soft tissue injury is
  I.C.E. along with prescribed pharmacologic agents
  and supervised rehabilitative exercise.

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The Role of Exercise Rehabilitation

• Properly supervised physical activity is most
  effective for many injuries.
• Such exercise can have a positive effect on
  collagen formation.

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The Role of Exercise Rehabilitation

• Collagen formation and tissue degeneration
  requires 2-3 weeks.
• Rehabilitation programs must be supervised by
  professionals with appropriate training, ATC or
  PT
• Rehabilitative exercise - four phases
• Passive, assisted, active, resistive