Download Chapter 9: Mechanisms and Characteristics of Sports Trauma

Chapter 9: Mechanisms and
Characteristics of Sports Trauma
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
• Tissue Properties
– Relative abilities to resist a particular load
– Strength, pressure of power is used to imply
force (defined as a push or pull)
– Load can be a singular or group of outside
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
• 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
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
parts of including tendons
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
• 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
– 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
Skeletal Muscle Injuries
• High incidence in athletics
• Anatomical Characteristics
– Composed of contractile cells that produce
movement
– Possess following characteristics
•
•
•
•
Irritability
Contractility
Conductivity
Elasticity
– Three types of muscle
• Cardiac
• Smooth
• Striated
Skeletal Muscle
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
– Can penetrate to skeletal structures causing a
bone bruise
– Usually rated by the extent to which muscle is
able to produce range of motion
• Strains
– Stretch, tear or rip to muscle or adjacent tissue
– Cause is often obscure
• Abnormal muscle contraction (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
– Muscle Strain Grades
• Grade I - some fibers have been stretched or actually
torn resulting in tenderness and pain on active
ROM, movement painful but full range present
• Grade II - number of fibers have been torn and
active contraction is painful, usually a depression or
divot is palpable, some swelling and discoloration
result
• Grade III- Complete rupture of muscle or
musculotendinous junction, significant impairment,
with initially a great deal of pain that diminishes due
to nerve damage
– Pathologically, strain is very similar to
contusion or sprain with capillary or blood
vessel hemorrhage
• Tendon Injuries
– Wavy parallel collagenous fibers organized in
bundles - upon loading (up to 8,700- 18,000
lbs) collagen straightens but will return to shape
after loading
– Breaking point occurs at 6-8% of increased
length
– Tears generally occur in muscle and not tendon
– Repetitive stress on tendon will result in
microtrauma and elongation, causing
fibroblasts influx and increased collagen
production
• May evolve into chronic muscle condition ,
weakening tendons
• Muscle Cramps and Spasms
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–
–
–
Painful involuntary contraction
Attributed to dehydration/electrolyte imbalance
Reflex reaction caused by trauma
Two types
• Clonic - alternating involuntary muscular
contractions and relaxations in quick succession
• Tonic - rigid contraction that lasts a period of time
– May lead to muscle or tendon injuries
Overexertional Muscle Problems
• Reflective in muscle soreness, decreased
joint flexibility, general fatigue (24 hours
post activity)
• Muscle Soreness
– Overexertion in strenuous exercise resulting in
muscular pain
– Generally occurs following participation in
activity that individual is unaccustomed
– 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
• 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
– Related to hard conditioning
– Tonic - result of electrolyte imbalance or
interruption of muscle synergism
– Clonic - stems from nerve irritation
• 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
Myofascial Trigger Points
• Area of tenderness in a tight band of muscle
• Develop as the result of mechanical stress
– Either acute strain or static postural positions
producing constant tension in muscle
• Typically occur in neck, upper and lower
back
• Pain with palpation, with predictable pattern
of referred pain which may also limit motion
• Pain may increase with active and passive
motion of involved muscle
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
• 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
• 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
• Atrophy and Contracture
– Atrophy is wasting away of muscle due to
immobilization, inactivity, or loss of nerve
functioning
– Contracture is and abnormal shortening of
muscle where there is a great deal of resistance
to passive stretch
• Generally the result of a muscle injury which
impacts the joint, resulting in accumulation of scar
tissue
Synovial Joints
• Anatomical Characteristics
– Consist of cartilage and fibrous connective tissue
– Joints are classified as
• Synarthrotic - immovable
• Amphiarthrotic - slightly moveable
• Diarthrotic - freely moveable (synovial articulations)
– Synovial Joint characteristics
•
•
•
•
Capsule or ligaments
Capsule is lined with synovial membrane
Hyaline cartilage
Joint cavity with synovial fluid
• Joint Capsule
– Bones are held together by a fibrous cuff
– Consists of bundles of collagen and function to
maintain relative joint position
– Extremely strong and can withstand cross
sectional forces
– Will be slack or taut depending on joint
movement
• 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
– 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 Roux’s law of functional
adaptation (organ will adapt structurally to
alteration qualitative or quantitative of function)
• Synovial Membrane
–
–
–
–
Lines articular capsule
Single layer of flattened cells and villi
Secretes and absorbs fluid - serves as lubricant
Fluid contains hyaluronic acid (changes viscosity)
• Fast movement - thins fluid
• Slow movement - fluid thickens
• Articular Cartilage
– Provides firm flexible support - semifirm
connective tissue with primarily ground substance
– No direct blood or nerve supply
– Fibrocartilage: makes up vertebral disks,
symphysis pubis and menisci
– Elastic: external ear and eustachian tubes
– Hyaline: composes nasal septum, larynx,
trachea, bronchi, and articular ends of bone
• Covers ends of bones in diarthrodial joints which
serves as cushion and sponge
• Can undergo compression and return to normal
shape
• Degeneration producing microtrauma can occur
following abnormal compressive forces
• Receives nourishment from synovium
• Provides motion control, stability and load
transmission
• Additional Synovial Joint Structures
– Fat
• Pads located in elbow, knee, to fill spaces between
bones that form joints (lie between synovial
membrane and the capsule)
– Articular Disks
•
•
•
•
•
Additional fibrocartilanginous disks
Vary in shape and size and connected to capsule
Exist in joints that operate in 2 planes of motions
Aid in dispersion of synovial fluid
Meniscus
• Nerve Supply
– Capsule, ligaments, outer aspects of synovial
membrane and fat pads are well supplied
– Inner structures (synovial membrane, cartilage
and articular cartilage) also supplied
– Myelinated mechanoreceptors provide joint
position sense in fibrous capsule
– Non-myelinated fibers supply blood vessels and
pain receptors
• Types of Synovial Joints
– 6 types
•
•
•
•
ball and socket - allows movement in all plane (hip)
hinge - allows for flexion and extension (elbow)
pivot - rotation about and axis (cervical atlas and axis)
ellipsoidal - elliptical convex and concave articulation
(wrist)
• saddle - reciprocally convex-concave (carpometacarpal
joint of thumb)
• gliding - all sliding back and forth (carpal joints)
• hinge, pivot, ellipsoidal, saddle, and gliding
• Functional Synovial Joints
– Differ in their ability to withstand trauma
depending on skeletal, ligamentous, and muscular
organization
– Synovial Joint Stabilization
• Muscle tension helps to limit synovial joint movement
• With stretching of the capsule, muscle reflex
contractions prevent overstretching
• Nerve supply is governed by Hilton’s Law (capsule,
skin and muscle have same nerve supply)
• Ligaments can extend due to right angle structural
design but are not elastic
• Joint structure vs. ligament contribution to joint
stability
• Muscles absorb forces involved in load transmission
and may provide dynamic stabilizing through
integration into joint capsule and by crossing joints
– Articular Capsule and Ligaments
• Help maintain anatomical integrity and structural
alignment of joints
• Ligaments have spiral arrangement of collagenous
tissue
• Ligaments tend to be stronger in the middle and
weak at the ends
• Respond quicker than muscle to over-stretching
• Synovial Joint Trauma
– Major factor in injury is viscoelastic properties of
ligaments and capsule
– While constant compression is damaging, periodic
tension increases overall strength of tissue
– Subject to same mechanical forces that cause injury
• Synovial Joint Injury Classifications
– Acute Joint Injuries
– Sprains
• Result of traumatic joint twist that causes stretching or
tearing of connective tissue
• Graded based on the severity of injury
• Grade I - some pain, minimal loss of function, no
abnormal motion, and mild point tenderness
• Grade II - pain, moderate loss of function, swelling,
and instability
• Grade III - extremely painful, inevitable loss of
function, severe instability and swelling, and may
also represent subluxation
• Can result in joint effusion and swelling, local
temperature increase, pain and point tenderness,
ecchymosis (change in skin color) and possibly an
avulsion fracture
• Most vulnerable joints include ankles, knees, and
shoulders
• Sometimes difficult to distinguish between sprain
and tendon strain
• Repeated joint twisting could result in arthritis or
– 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)
• 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”
• 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 absorption of
impact forces
– Osteochondrosis
• Also known as osteochrondritis dissecans
and apophysitis (if located at a
tubercle/tuberosity)
• Causes not well understood
• Degenerative changes to epiphyses of bone during
rapid child growth
• Possible cause includes 1)aseptic necrosis (disrupted
circulation to epiphysis, 2) fractures in cartilage
causing fissures to subchondral bone, 3) trauma to a
joint that results in cartilage fragmentation resulting
in swelling, pain and locking
• With the apophysis, an avulsion fracture may be
involved, including pain, swelling and disability
– Osteoarthritis
• Wearing away of hyaline cartilage as a result of
normal use
• Changes in joint mechanics lead joint degeneration
(the result of repeated trauma to tissue involved)
• May be the result of direct blow, pressure of
carrying and lifting heavy loads, or repeated trauma
from an activity such as running or cycling
• Commonly affects weight bearing joints but can also
impact shoulders and cervical spine
• Symptoms include pain (as the result of friction),
stiffness, prominent uprising in the morning,
localized tenderness, creaking, grating, and often is
localized to one side of the joint or generalized joint
pain
– Bursitis
• Fluid filled sac that develops in area 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
– Capsulitis and Synovitis
• Capsulitis is the result of repeated joint trauma
• Synovitis can occur acutely but will also develop
following mistreatment of joint injury
• Chronic synovitis can result in edema, thickening of the
synovial lining, exudation can occur and a fibrous
underlying develops --motion may be restricted and joint
Skeletal Trauma
• Anatomical
Characteristics
– Dense connective
tissue matrix
– Outer compact tissue
– Inner porous
cancellous bone
including Haversian
canals
– Bone Functions
•
•
•
•
•
Body support
Organ protection
Movement (through joints and levers)
Calcium storage
Formation of blood cells (hematopoiesis)
– Types of Bone
•
•
•
•
•
Classified according to shape
Flat bones - skull, ribs, scapulae
Irregular bones - vertebrae and skull
Short bones- wrist and ankle
Long bones - humerus, ulna, tibia, radius, fibula,
femur
- bones most commonly injured
– Gross Structures
• Diaphysis -shaft - hollow and cylindrical
- covered by compact bone)
- medullary cavity contains yellow
marrow
• 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
– Microscopic Structures
• Calcium salts impregnate intracellular bone
substance (makes bone hard)
• Osteocytes located in hollow spaces are called
lacunae
• Haversian systems are the structural units of bone
• Compact bone has interspersed lamellae to fill
spaces between canals
• Cancellous bone has numerous open spaces between
thin processes of trabeculae
• Trabeculae serve as scaffolding and align along
points of stress within the bone to add structural
strength
• Blood circulation connects perisosteum with
haversian canals through Volkmann’s canal
• Medullary cavity and bone marrow are supplied
directly by one or more arteries
– Bone Growth
• Ossification occurs from synthesis of bones organic
matrix (work of osteoblasts and osteoclasts)
• Involves the epiphyseal growth plates located at the
ends of long bones
• As cartilage matures, immature osteoblasts replace
to ultimately form bone
• Deforming forces, premature injury and growth
plate dislocation can alter growth patterns and/or
result in deformity of bone
• Bone diameter increases via the activity of
osteoblasts adding to the exterior while osteoclasts
break down bone in medullary cavity
• At full size, bone maintains state of balance between
osteoblastic and -clastic activity
• Changes in activity and hormonal levels can alter
balance
• Bone loss begins to exceed external bone growth
overtime
• As thickness decreases, bones are less resistant to
forces --osteoporosis
• Bone’s functional adaptation to stresses follow’s
Wolff’s Law --every change in form and function or
in its function alone is followed by changes in
architectural design
• Bone Injuries
– While 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
– Load Characteristics
• Bones can be stressed or loaded to fail by tension,
compression, bending, twisting and shearing
• Either occur singularly or in combination
• Amount of load also impact the nature of the
fracture
• More force results in a more complex fracture
• While force goes into fracturing the bone, energy
and force is also absorbed by adjacent soft tissues
• Some bones will require more force than others
• Bone’s magnitude of stress and strain in most
prevalent at it outer surface and decreases to zero at
its center
– Bone Trauma Classifications
• Periostitis - inflammation of the periosteum, result
primarily of contusions and produces rigid skin
overlying muscle (acute and chronic)
• Acute bone fractures - partial or complete
disruption that can be either closed or open (through
skin); serious musculoskeletal condition
• Type of fractures include, depressed, greenstick,
impacted, longitudinal, oblique, serrated, spiral,
transverse, comminuted, blowout, and avulsion
• Stress fractures- no specific cause but with a
number of possible causes
– Overload due to muscle contraction, altered stress
distribution due to muscle fatigue, changes in surface,
rhythmic repetitive stress vibrations
• 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
–
–
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–
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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
• Major signs and symptoms include focal tenderness
and pain, (early stages) pain with activity, (later
stages) pain becomes constant and more intense,
particularly at night, 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)
• 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 yrs. 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 Sever’s disease and
Osgood-Schlatter’s disease
Nerve Trauma
• Abnormal nerve responses can be attributed
to injury or athletic participation
• The most frequent injury is neuropraxia
produced by direct trauma
• Lacerations of nerves as well as
compression of nerves as a result of
fractures and dislocations can impact nerve
function
• Anatomical Characteristics
– Provides sensitivity and communication from
the CNS to muscles, sense organs and various
systems in the periphery
– Neuron cell body has a large nucleus with
branched dendrites which respond to
neurotransmitter substances
– Each nerve cell has an axon that conducts nerve
impulse
– Axons are encased in neurilemmal sheaths
(Schwann and satellite cells)
– Various neurological cells in CNS help to form
framework for nervous tissue
• Nerve Injuries
– Two main causes of injury - compression and
tension
– May be acute or chronic
– Physical trauma causes pain and can result in a
host of sensory responses (pinch, burn, tingle,
muscle weakness, radiating pain)
– Long term problems (neuritis) can go from
minor nerve problems to paralysis
– Pain can be referred as well
Body Mechanics
• Body move 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
• 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, OsgoodSchlater’s disease, runner’s and jumper’s knee,
patellar chondromalacia and apophyseal avulsion
• Postural Deviations
– Often an underlying cause of injury
– May cause unilateral muscle use as well as
bony and soft tissue asymmetries
– Results in poor pathomechanics
– Imbalance is manifested by postural deviations
as body tries to regain balance relative to CoG
– Injury generally becomes chronic and
participation must stop
– Athletic trainer should attempt to correct
postural conditions
– Postural conditions can make athletes
exceedingly more prone to injury