Chapter 9 Mechanisms and Characteristics of Sports Trauma

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Chapter 9 Mechanisms and Characteristics of
Sports Trauma
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Mechanical Injury

• Trauma is defined as physical injury or wound
  sustained in sport, produced by internal or
  external force
• Mechanical injury results from force or
  mechanical energy that changes state of rest or
  uniform motion of matter
• Injury in sports can be the result of external
  forces directed on the body or can occur within
  the body internally

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• Tissue Properties
• Relative abilities to resist a particular load
• Strength pressure or power is used to imply force
  (defined as a push or pull)
• Load can be a singular or group of outside or
  internal forces acting on the body.
• Stress is resistance to a load
• Body tissues are viscoelastic and contain both
  viscous and elastic properties
• Point at which elasticity is almost exceeded is
  the yield point
• When exceeded mechanical failure occurs resulting
  in damage

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• Tissue Stresses
• Tension (force that pulls and stretches tissue)
• Stretching (pull beyond yield point resulting in
  damage)
• Compression (force that results in tissue crush)
• Shearing (force that moves across the parallel
  organization of tissue)
• Bending (force on a horizontal beam that places
  stress within the structure)

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Soft Tissue Trauma

• Soft tissue or non -bony tissue is categorized as
  inert (noncontractile) and contractile tissue
• Inert tissues include, ligaments, skin,
  cartilage, capsules, fascia, dura mater and nerve
  roots
• Contractile tissue involves muscles and its parts
  including tendons and bony insertions

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Skin Injuries

• Break in the continuity of skin as a result of
  trauma
• Anatomical Considerations
• Skin (external covering) or integument represents
  the largest organ of the bogy and consists of 2
  layers
• Epidermis
• Dermis (corium)
• Soft pliable nature of skin makes it easy to
  traumatize

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• Injurious Mechanical Forces
• Include friction, scraping, compression, tearing,
  cutting and penetrating
• Wound Classifications
• Friction blister
• continuous rubbing over skin surface that causes
  a collection of fluid below or within epidermal
  layer
• Abrasion
• Skin is scraped against rough surface resulting
  in capillary exposure due to skin removal
• Skin Bruise (contusion)
• Compression or crush injury of skin surface that
  produces bleeding under the skin

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• Laceration
• Wound in which skin has been irregularly torn
• Skin Avulsion
• Skin that is torn by same mechanism as laceration
  to the extent that tissue is completely ripped
  from source
• Incision
• Wound in which skin has been sharply cut
• Puncture
• Penetration of the skin by a sharp object

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Acute Muscle Injuries

• Contusions
• Result of sudden blow to body
• Can be both deep and superficial
• Hematoma results from blood and lymph flow into
  surrounding tissue
• Localization of extravasated blood into clot,
  encapsulated by connective tissue
• Speed of healing dependent on the extent of damage

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• Can penetrate to skeletal structures causing a
  bone bruise
• Usually rated by the extent to which muscle is
  able to produce range of motion
• Blow can be so severe that fascia surrounding
  muscle ruptures allowing muscle to protrude
• Signs Symptoms of Severe Contusions
• Athlete reports being struck by hard object
• Impact causes pain and transitory paralysis
• Due to pressure on and shock to motor and sensory
  nerves
• Palpation reveals hardened area
• Possible ecchymosis or tissue discoloration

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• Strains
• Stretch, tear or rip to muscle or adjacent tissue
• Cause is often obscure
• Abnormal muscle contraction is the result of
  1)failure in reciprocal coordination of agonist
  and antagonist, 2) electrolyte imbalance due to
  profuse sweating or 3) strength imbalance
• May range from minute separation of connective
  tissue to complete tendinous avulsion or muscle
  rupture

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Overexertional Muscle Problems

• Reflective in muscle soreness, decreased joint
  flexibility, general fatigue (24 hours post
  activity)
• 4 indicators of possible overexertion
• Muscle Soreness
• Overexertion in strenuous exercise resulting in
  muscular pain
• Generally occurs following participation in
  activity that individual is unaccustomed

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• Two types of soreness
• Acute-onset muscle soreness - accompanies
  fatigue, and is transient muscle pain experienced
  immediately after exercise
• Delayed-onset muscle soreness (DOMS) - pain that
  occurs 24-48 hours following activity that
  gradually subsides (pain free 3-4 days later)
• Potentially caused by slight microtrauma to
  muscle or connective tissue structures
• Prevent soreness through gradual build-up of
  intensity
• Treat with static or PNF stretching and ice
  application within 48-72 hours of insult

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• Muscle Stiffness
• Does not produce pain
• Result of extended period of work
• Fluid accumulation in muscles, with slow
  reabsorbtion back into bloodstream, resulting in
  swollen, shorter, thicker muscles --resistant to
  stretching.
• Light activity, motion, massage and passive
  mobilization assists in reducing stiffness
• Muscle Cramps
• Painful involuntary skeletal muscle contraction
• Occurs in well-developed individuals when muscle
  is in shortened position
• Experienced at night or at rest

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• Muscle Guarding
• Following injury, muscles within an effected area
  contract to splint the area in an effort to
  minimize pain through limitation of motion
• Involuntary muscle contraction in response to
  pain following injury
• Not spasm which would indicate increased tone due
  to upper motor neuron lesion in the brain

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Chronic Musculoskeletal Injuries

• Progress slowly over long period of time
• Repetitive acute injuries can lead to chronic
  condition
• Constant irritation due to poor mechanics and
  stress will cause injury to become chronic
• Chronic muscle injuries
• Representative of low grade inflammatory process
  with fibroblast proliferation and scarring
• Acute injury is improperly managed

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• Myositis/fascitis
• Inflammation of muscle tissue
• Fibrositis or inflammation of connective tissue
• Plantar fascitis
• Tendinitis
• Gradual onset, with diffuse tenderness due to
  repeated microtrauma and degenerative changes
• Obvious signs of swelling and pain
• Tenosynovitis
• Inflammation of synovial sheath
• In acute case - rapid onset, crepitus, and
  diffuse swelling
• Chronic cases result in thickening of tendon with
  pain and crepitus

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• Ectopic Calcification (myositis ossificans)
• Striated muscle becomes chronically inflamed
  resulting in myositis
• Can result in muscle that lies directly above
  bone
• Osteoid material accumulates rapidly and will
  either resolve in 9-12 months or mature with
  repeated trauma
• With maturation, surgery is required for removal
• Common sites, quadriceps and brachial muscle

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• Ligaments
• Sheets or bundles of collagen that form
  connection between two bones
• Both intrinsic (inside the capsule) and extrinsic
  (outside the capsule)
• Similar composition to tendons
• Strong in the middle, weak at the ends
• When placed under undo stress may result in
  avulsion injury
• Viscoelastic properties are primary factor in
  ligamentous injuries

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• Constant compression or tension causes ligament
  deterioration while intermittent stress
  strengthens
• Repeated microtrauma overtime makes capsule and
  ligaments more susceptible to major acute
  injuries
• Act as protective backup for joint
• Primary protection is dynamic action of muscle
• Under fast loading conditions, ligament will
  fail, however, they provide maximal protection
  during rapid movements
• Will adapt based on Rouxs law of functional
  adaptation (organ will adapt structurally to an
  alteration, qualitative or quantitative of
  function)

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• Acute Synovitis
• Synovial membrane can be acutely injured via
  contusion or strain
• Irritation of membrane results in increased fluid
  production and swelling occurs
• Results in joint pain along with skin sensitivity
• With proper treatment, effusion and pain will
  diminish
• Subluxations, Dislocations and Diastasis
• High level of incidence in fingers and shoulder
• Subluxations are partial dislocations causing
  incomplete separation of two bones
• Luxation presents with total disunion of bone
  apposition between articular surfaces
• Diastisis is the disjointing of 2 parallel bones
  or rupture of a solid joint (symphysis pubis)

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• Factors associated with dislocations - 1) loss of
  limb function, 2) gross deformity, 3)swelling and
  point tenderness
• X-ray is the only absolute diagnostic technique
  (able to see bone fragments from possible
  avulsion fractures, disruption of growth plates
  or connective tissue)
• Dislocations (particularly first time) should
  always be considered and treated as a fracture
  until ruled out
• Once a dislocation, always a dislocation

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• Chronic Joint Injuries
• Stem from microtrauma and overuse
• Include, osteochondrosis, osteoarthritis, and in
  adolescence epiphyseal injuries
• Major cause involves failure of muscle to control
  or limit deceleration
• To prevent, a combination of chronic fatigue and
  training should be avoided, and protective gear
  should be used to enhance active absorption of
  impact forces

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• Bursitis
• Bursa are fluid filled sacs that develop in areas
  of friction
• Sudden irritation can cause acute bursitis, while
  overuse and constant external compression can
  cause chronic bursitis
• Signs and symptoms include swelling, pain, and
  some loss of function
• Repeated trauma can lead to calcification and
  degeneration of internal bursa linings

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• Gross Structures
• Diaphysis - shaft - hollow and cylindrical
• - covered by compact bone
• - medullary cavity contains yellow
• marrow and lined by
  endosteum
• Epiphysis - composed of cancellous bone and
• has hyaline cartilage
  covering
• - provides areas for muscle
  attachment
• Periosteum - dense, white fibrous covering which
• penetrates bone via
  Sharpey fibers
• - contains blood vessels
  and osteoblasts

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• Bone Injuries
• While bones have viscoelastic properties, bone
  is fairly rigid and serves as a poor shock
  absorber
• Brittle nature increases under tension rather
  than compression
• Cylindrical nature of bones make them very strong
  - resistant to bending and twisting
• Anatomical Weak Points
• Stresses become concentrated in areas where
  changes in shape and direction occur
• Gradual changes in shape are much more
  advantageous

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• Load Characteristics
• Bones can be stressed or loaded to failure by
  tension, compression, bending, twisting and
  shearing
• Either occur singularly or in combination
• Amount of load also impacts the nature of the
  fracture
• More force results in a more complex fracture
• While force goes into fracturing the bone, some
  energy and force is also absorbed by adjacent
  soft tissues
• Some bones will require more force than others
• Bones magnitude of stress and strain is most
  prevalent at it outer surface and decreases to
  zero at its center

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• Bone becomes susceptible early in training due
  to increased muscular forces and initial
  remodeling and resorption of bone
• Progression involves, focal microfractures,
  periosteal or endosteal response (stress fx)
  linear fractures and displaced fractures
• Typical causes include
• Coming back to competition too soon after injury
• Changing events without proper conditioning
• Starting initial training too quickly
• Changing training habits (surfaces, shoes.etc)
• Variety of postural and foot conditions
• Early detection is difficult, bone scan is
  useful, x-ray is effective after several weeks

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• Major signs and symptoms include focal tenderness
  and pain, (early stages) pain with activity,
  (later stages) with pain becoming constant and
  more intense, particularly at night, (exhibit a
  positive percussion tap test)
• Common sites involve tibia, fibula, metatarsal
  shaft, calcaneus, femur, pars interarticularis,
  ribs, and humerus
• Management varies between individuals, injury
  site and extent of injury
• More easily managed and healed if on compression
  side of bone vs. tension (may result in complete
  fx)

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• Epiphyseal Conditions - three types can be
  sustained by adolescents (injury to growth plate,
  articular epiphysis, and apophyseal injuries)
• Occur most often in children ages 10-16 years old
• Classified by Salter-Harris into five types (see
  photo on next slide)
• Apophyseal Injuries - Young physically active
  individuals are susceptible
• Apophyses are traction epiphyses in contrast to
  pressure epiphyses.
• Serve as sites of origin and insertion for
  muscles
• Common avulsion conditions include Severs
  disease and Osgood-Schlatters disease

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Body Mechanics and Injury Susceptibility

• Body moves very effectively in upright position -
  able to overcome great forces even with
  inefficient lever system
• Body must overcome inertia, muscle viscosity and
  unfavorable angles of pull
• Mechanical reasons for injury - hereditary,
  congenital, or acquired defects may predispose
  athlete to injury
• Body build, structural make-up, habitual
  incorrect application of skill may also
  predispose individual to injury

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• Microtrauma and Overuse Syndrome
• Injuries as a result of abnormal and repetitive
  stress and microtraumas fall into a class with
  certain identifiable syndromes
• Frequently result in limitation or curtailment of
  sports involvement
• Often seen in running, jumping, and throwing
  activities
• Some of these injuries while small can be
  debilitating
• Repetitive overuse and stress injuries include
• Achilles tendinitis, shin splints, stress fx,
  Osgood-Schlaters disease, runners and jumpers
  knee, patellar chondromalacia and apophyseal
  avulsion

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• Postural Deviations
• Often an underlying cause of injury
• May be the result of unilateral muscle or bony
  and soft tissue asymmetries
• Sports activities may cause asymmetries to
  develop
• Results in poor pathomechanics
• Imbalance is manifested by postural deviations as
  body tries to regain balance relative to CoG
• May be primary cause of injury