Chapter 8
The Injury Process
The Physics of Sports Injury
Connective Tissue
• Connective tissues are the most common
type of tissue in the body.
• Connective tissues include ligaments,
retinaculum, joint capsules, bone, cartilage,
fascia, and tendons.
• In some sports, nearly 50% of acute
injuries involve either tendon or muscle.
The Physics of Sports Injury
(cont.)
Muscle/fascia are thought to be injured by
excessive tension during contractions.
• Tendons are extremely strong structures;
strains occur most often at the distal
musculotendinous junction (MTJ).
• These strains are the most common soft
tissue injuries related to sports.
Mechanical Forces of Injury
Types of Force
• Compressive
• Tensile
• Shear
Mechanical Forces of Injury
(cont.)
• Tendons resist tensile forces.
• Bones resist compressive forces.
• Ligaments resist tensile forces.
Each type of tissue has a limit for how much
force it can withstand (critical force).
The Physiology of Sports
Injury
The inflammatory process:
• Is a predictable sequence of physiologic
actions that occur when the body reacts in a
manner to repair damaged tissues.
• Begins during the first few minutes following
an injury.
The body’s initial response to trauma is
commonly called swelling.
The Inflammatory Process
(cont.)
Normal signs and symptoms of inflammation
include:
• Swelling.
• Pain.
• Reddening of skin (erythema).
• Increased temperature in the affected area.
Acute Inflammatory Phase
• Initial trauma destroys millions of cells.
• Vasoconstriction is followed by vasodilation.
• Damage to blood vessels results in blood flow
into interstitial spaces causing a hematoma.
• A hematoma is the “localized collection of
extravasted blood.”
• Secondary hypoxic injury results in additional
cellular destruction.
Acute Inflammatory Phase
(cont.)
In response to injury, chemicals are released
that affect nearby cells. The effects of these
chemicals are:
• Degradative (cellular breakdown).
• Vasoactive (vasodilators).
• Chemotactic (attract scavenger cells).
Acute Inflammatory Phase
(cont.)
Hageman Factor is responsible for the
manufacture of bradykinin.
• Bradykinin increases vascular
permeability and triggers the release of
prostaglandins resulting in:
• Vasodilation.
• Increased vascular permeability.
• Pain.
• Blood clotting.
Acute Inflammatory Phase
(cont.)
• Plasma proteins, platelets, and leukocytes
move out of capillaries and into damaged
tissue.
• Leukocytes engage in phagocytosis (damaged
cell absorption).
• Macrophages migrate into the damaged area.
Arachidonic acid is formed by a combination of
leukocyte enzymes and phospholipids derived
from cell membranes.
• Arachidonic acid catalyzes the production of
leukotrienes.
Acute Inflammatory Phase
(cont.)
The acute inflammatory process results in a
walling off of the damaged area from the rest
of the body.
The process acts to clean up the debris and
provide components for healing.
The acute phase lasts up to 3 or 4 days, unless
aggravated by additional trauma.
Resolution (Healing) Phase
During this phase, special leukocytes
(polymorphs and monocytes) and a type of
macrophage (histocytes) migrate into the
area of injury.
• These cells break down cellular debris and
set the stage for regeneration and repair.
Regeneration and Repair
Except for bone, connective tissues heal by
forming scar tissue that begins to develop 3–
4 days after the injury.
• Fibroblasts (proteoglycan- and collagenproducing cells) migrate into the damaged
area.
• Fibroblasts are immature connective tissue
fibers that can mature into several different
types of cells.
Regeneration and Repair
(cont.)
• Angiogenesis is the formation of new
capillaries.
• Scar formation may take up to four
months.
• Scar tissue can be 95% as strong as
the original tissue. Stress on the tissue
is helpful for rehabilitation; exercises
are critical to this process.
• Bone tissue heals by way of specialized
cells (osteoclasts and osteoblasts).
Pain and Acute Injury
• Everyone copes with pain differently.
• Pain is as much psychological as
physiological.
• Pain results from sensory input received
through the nervous system and indicates
location of tissue damage.
• Messages concerning sensory information
that travel quickly through the nervous system
are given higher priority than pain messages
that travel more slowly.
• Pain is not a useful indicator of injury severity.
Intervention Procedures
• Sports medicine community has no clear set
of criteria for first aid treatment of acute softtissue injury.
Cryotherapy includes bags of crushed ice,
aerosol coolants, ice cups, ice water
immersion, and commercial cold packs.
After the acute phase, thermotherapy is
appropriate (i.e., hydrocollator packs, moist
warm towels, and ultrasound diathermy).
Intervention Procedures
(cont.)
• Modalities such as ultrasound should ONLY be
used under the supervision of trained allied
health personnel.
• Pharmacologic agents can be used, such as
anti-inflammatories and analgesics.
• If they must be prescribed by a physician,
these agents represent treatments that are
beyond the scope of the coach.
• OTC drugs should also be used with caution.
(Consult parents when athlete is under 18 years
of age.)
Cryotherapy
• Direct application of
cold may reduce
vasodilation in the first
few minutes after
injury.
• Application of cold
can decrease
recovery time by
reducing secondary
hypoxic injury.
Courtesy of Ron Pfeiffer
Cryotherapy (cont.)
• In extremities, elevation and compression are
also helpful in treatment.
• Crushed ice in a plastic bag is an inexpensive
modality.
• Elastic wrap secures the ice bag to the body.
• Cold application has analgesic effect and
reduces muscle spasm.
• Recommended protocol: Apply for 20
minutes, remove for 2 hours, and reapply for
another 30 minutes, if needed.
• Risk of frostbite is minimal with crushed ice.
Thermotherapy
Thermotherapeutic agents:
• Should NEVER be applied to
an acute injury.
• Increase vasodilation.
• Are useful in the final phases
of injury repair.
Pharmacologic Agents
Steroidal and NSAIDs
• Both affect aspects of the inflammatory process.
• Steroidal drugs resemble gluococorticoids, but
the exact mechanism of their action is unknown.
Steroids may:
• Decrease amount of chemicals released by
lysosomes.
• Decrease permeability of capillaries.
• Reduce WBC phagocytosis.
• Reduce local fever.
Pharmacologic Agents
(cont.)
Steroids must be used with care.
• They can interfere with collagen
formation, decreasing connective tissue
strength in injured area.
Steroids may be injected or taken orally and
include drugs such as:
• Cortisone, hydrocortisone, prednisone,
prednisolone, triamcinolone, and
dexamethasone.
NSAIDs
NSAIDs do not have the negative effects of
steroids.
• NSAIDs are very popular drugs.
• Common NSAIDs include aspirin,
ibuprofen, naproxen, indomethacin,
and naproxen sodium.
NSAIDs (cont.)
• NSAIDs block the conversion of arachidonic
acid to prostaglandin.
• Aspirin has anti-inflammatory, analgesic, and
antipyretic effects.
• Research is inconclusive regarding NSAIDs’
effect on tissue healing and strength.
RICE
Best approach to the care of soft tissue injury is
RICE along with prescribed pharmacologic
agents and supervised rehabilitative exercise.
R = Rest
I = Ice
C = Compression
E = Elevation
The Role of Exercise
Rehabilitation
• Properly supervised
physical activity is
very effective for
many injuries.
• Such exercise can
have a positive
effect on collagen
formation.
© AbleStock
Exercise Rehabilitation
• Collagen formation and tissue regeneration
require 2 to 3 weeks.
• Rehabilitation must be supervised by
professionals with appropriate training, such
as a BOC-certified Athletic Trainer or a
Physical Therapist with sports medicine
training.
Exercise Rehabilitation
(cont.)
Rehabilitative exercise is a four-phase
process.
• Passive exercise
• Active assisted
• Active exercise
• Resistive
Injury Rehabilitation
• Injury rehab should be considered an ongoing
process.
• Injury-specific exercise should be a
permanent component in training and
conditioning.
• Without this approach, the likelihood of
reinjury is high.