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Chapter 9: Mechanisms and Characteristics of Musculoskeletal and Nerve Trauma
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2. What is one of the main roles of an Athletic Trainer?
Recognizing a specific injury to a musculoskeletal or nerve structure and the mechanical forces that produce that trauma.
Trauma: a physical injury or wound produced by an external or internal force.
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3. Tissue Properties Load Stiffness Stress Strain
An external force acting on the body causing internal reactions within the tissues
Stiffness
Ability of a tissue to resist a load
Greater stiffness = greater magnitude load can resist
Stress
Internal resistance to a load
Strain
Internal change in tissue (i.e. length) resulting in deformation (change)
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4. Tissue Properties continued
Elasticity: Property that allows tissue to return to normal after deformation
Yield point: when tissue is deformed to the extent that is not longer reacts elasticity
Plastic: when a load is removed, deformation of the tissue to an extent remains
Creep: Deformation of a tissue over a period of time
Mechanical Failure: exceeding the ability of the tissue to withstand the load and the tissue breaks down
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Figure 9-1
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6. With this basic knowledge, explain an ankle sprain.
There is a load on the ankle causing stress and strain to the ligaments of the ankle. This causes deformation of the ligament due to the fact that the ligaments are plastic. Depending on the load the ligament may hit its yield point and cause mechanical failure.
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Tissue Loading
Tension (Figure B)
Force that pulls and stretches tissue
Compression (Figure A)
Force that results in tissue crush – two forces applied towards one another
Shearing (Figure C)
Force that moves across the parallel organization of tissue
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Bending (Figure D)
Two force pairs act at opposite ends of a structure (4 points)
Three forces cause bending (3 points)
Already bowed structures encounter axial loading
Torsion (Figure E)
Loads caused by twisting in opposite directions from opposite ends
Shear stress encountered will be perpendicular and parallel to the loads
Figure 9-2 D & E
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9. What are the 5 types of loads? Draw each of the loads.
Compression
Tension
Shearing
Bending
Torsion
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10. Traumatic vs. Overuse Injuries Acute vs. Chronic
Debate over acute vs. chronic injuries
When injury is acute – something has initiated the injury process (usually sudden)
Injury becomes chronic when it doesn’t properly heal (over a period of time)
Could define relative to mechanism
Traumatic (i.e. a direct blow) vs. Overuse (i.e. repetitive dynamic use over time)
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11. Classification and Load Characteristics of Injuries
Go to page 241 and pick an injury.
Define the injury.
Classify it (overuse or traumatic)
Explain the mechanism of the injury or load.
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12. Musculotendinous Injuries and the Anatomy
Musculotendinous Unit:
Muscle: contractile cells or fibers that produce movement; in athletics skeletal or striated muscle fibers are the most common injured
Tendon: thicker part of muscle that connects the muscle to the bone; resilient to injury
Fascia: Fibrous covering over the muscle
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Skeletal Muscle
Figure 9-3
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Muscle Strains
Stretch, tear or rip to muscle or its tendon
Cause is often:
Abnormal muscle contraction is the result of:
1)failure in reciprocal coordination of agonist and antagonist
2) electrolyte imbalance due to profuse sweating
3) strength imbalance
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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
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Rehabilitation
Time required for healing may be lengthy
Often involves large, force-producing muscles
Treatment and recovery may take 6-8 weeks depending on severity
Return to play too soon could result in re-injury
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Figure 9-4
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18. Name the Three Grades of Muscle Strains and Define Each.
Grade I: muscle fibers stretched and slightly torn; Some tenderness but minor main with Full ROM
Grade II: Some muscle fibers have been torn; Active contraction painful; Divot with palpation; some swelling and discoloration; ROM is decreased
Grade III: complete rupture of the muscle; No Active ROM or very limited; Pain is intense and then quickly diminishes
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Muscle Cramps
Painful involuntary skeletal muscle contraction
Can coincide with heat cramps due to excessive water loss or electrolytes
Muscle Guarding
Involuntary muscle contraction in response to pain following injury
The muscles that surround the injured area contract or splint the area
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Muscle Spasms
A 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
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Muscle Soreness: pain caused by overexertion in exercise
Generally occurs following participation in activity that individual is unaccustomed
Two types of soreness
Acute-onset muscle soreness - accompanies fatigue, and is pain experienced immediately after exercise
Delayed-onset muscle soreness (DOMS) - pain that occurs hours following activity that gradually subsides (pain free 3-4 days later)
Potentially caused by slight microtrauma to muscle or connective tissue structures, eccentric or isometric contractions
Prevent soreness through gradual build-up of intensity
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Review:
What are muscle cramps?
What are the two types of muscle spasms?
What does DOMS stand for?
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Tendon Injuries- connects muscle to bone
Can produce and maintain 8, ,000 lbs/in2
Collagen straightens during loading but will return to shape after loading
Breaking point occurs at 6-8% of increased length
Tears generally occur in muscle and not tendon
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24. Tendinitis: inflammation of the tendon
Mechanism: Gradual onset, due to microtrauma of the tendon respectively becomes irritated
Signs/ Symptoms: Swelling, pain, warmth, and crepitus (crackling feeling or sound)
Management: Key to treatment is rest (substitute an activity)
A: Normal B: Inflammed
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Tendonosis: Without proper healing tendinitis may begin to degenerate
Signs and Symptoms: Less inflammation, pain with movement or touching, stiffness and restricted motion
Management: Stretching and strengthening
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Tenosynovitis
Inflammation of the tendon and the synovial sheath
Acute case: rapid onset, crepitus, and diffuse swelling
Chronic cases: result in thickening of tendon with pain and crepitus
Often occurs in long flexor tendon of the digits and the biceps tendon
Due to nature of injury anti-inflammatory agents may be helpful (NSAIDs)
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Myofascial Trigger Points
Discrete, hypersensitive nodule within tight band of muscle or fascia (knots)
Classified as latent or active
Latent trigger point
Does not cause spontaneous pain, May restrict movement or cause muscle weakness, Become aware of presence when pressure is applied
Active trigger point
Causes pain at rest, Applying pressure = pain = jump sign, Tender to palpation with referred pain, Found most commonly in muscles involved in postural support
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28. LAB: Finding Trigger Points
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Contusions: AKA bruise; compression of soft tissue that results in bleeding into surrounding area
Mechanism: Result of sudden blow to body, Can be both deep and superficial
Signs and Symptoms: ecchymosis (bluish- purple discoloration of the skin), pain with palpation and movement
Myositis ossificans: Chronically inflamed and contused tissue may result in generation of calcium deposits, bone spurs in the muscle
Prevention through protection with padding
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Atrophy and Contracture
Atrophy: wasting away of muscle due to immobilization, inactivity, or loss of nerve functioning, muscle decreasing or weakening
Contracture is an abnormal shortening of muscle where there is a great deal of resistance to passive stretch usually due to scar tissue
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Part II
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32. Synovial Joints Injuries
2 or more bones the articulate (move) with one another to allow motion in one or more places
Additional synovial joint characteristics
Joint Capsule and ligaments (connect bone to bone) for support
Capsule is lined with synovial membrane (lubrication, shock absorption and nutrition)
Hyaline or articular cartilage
Blood and nerve supply with muscles crossing joint
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Ligament Sprains
When a stress or load is applied to the joint and forces motion beyond its normal limit, injury to the ligament is likely
Graded based on the severity of injury
Grade I – some stretching of fibers, minimal instability, mild to moderate pain, localized swelling and joint stiffness
Grade II – some tearing and seperation of the fibers, moderate instability, moderate to sever pain and swelling
Grade III – total tear of the ligament which leads to severe instability, severe to no pain, severe swelling, may have subluxation (joint slides out of place)
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Can result in joint effusion and swelling, local temperature increase, pain and point tenderness, ecchymosis (change in skin color) and possibly an avulsion fracture (pulling away from the bony structure)
Greatest difficulty with grade 1 & 2 sprains is restoring stability due to stretched tissue and inelastic scar tissue which forms
To regain joint stability strengthening of muscles around the joint is critical
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37. What are the 3 Grades of Sprains and Describe them?
Grade I: Some stretching, minimal instability, mild to moderate pain, localized swelling
Grade II: Some tearing and stretching, moderate instability, moderate to severe pain, moderate to severe swelling
Grade III: Total tear, instable, severe then no pain, severe swelling
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Dislocations and Subluxations
Result in separation of bony articulating surfaces (diastasis)
Dislocations: Occurs when at least one bone in a joint is forced out of alignment and must be manually or surgically reduced
High level of incidence in fingers and shoulder
Gross deformity is typically apparent with bilateral comparison revealing asymmetry
Subluxation: Partial dislocations causing incomplete separation of two bones
Bones come back together in alignment
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Dislocations and Subluxations (cont.)
Stabilizing structures of the joint are disrupted
Joint often becomes susceptible to subsequent dislocations or subluxations
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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Osteoarthritis: Wearing away of hyaline or articular cartilage may expose, erode and polish the underlying bone
Changes in joint mechanics lead to 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 morning pain, localized tenderness, creaking, grating
Either generalized joint pain or localized to one side of the joint
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Bursitis: Inflammation of the bursae usually at sites of bony prominence between muscles and tendon
Bursa are synovial 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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Questions:
What is the difference between an dislocation and a subluxation?
What causes osteoarthritis?
Where is bursitis commonly found?
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Bones
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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
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Bone Injuries
Anatomical Characteristics
Dense connective tissue consisting of bone cells or osteocytes
Outer compact tissue
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Gross Structures
Diaphysis -shaft - hollow and cylindrical, covered by compact bone
Epiphysis - composed of cancellous bone and has hyaline cartilage covering , provides areas for muscle attachment
Periosteum - dense, white fibrous covering, contains blood vessels and osteoblasts
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Bone Growth
Epiphyseal Growth Plate: near the end of each long bone, aid in the growth of bone (growth plate)
Injury to this can cause deformity or disruption in growth
Bone Diameter caused by
Osteoblasts: bone-producing cells
Osteoclast: bone- remodeling cells
Leads to osteogenesis- bone formation
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QUESTIONS:
Name some functions of bones. Name and describe the 3 gross anatomy of a bone. How does bone grow?
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Bone Fractures:
Closed fractures: where there is little movement or displacement
Open fractures: involves displacement of the fractured ends and breaking through the surrounding tissue
Serious condition if not managed properly
Signs & symptoms
Deformity, pain, point tenderness, swelling, pain on active and passive movements
Possible crepitus
X-ray will be necessary for definitive diagnosis
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Mechanism of Injury
Fracture may be direct (at point of force application) or indirect
Sudden violent and forceful muscle contraction
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Types of Fractures
Greenstick: incomplete breaks in the bone, adolescents Comminuted: 3 or more fragments at the fracture site Linear: bone split along its length Transverse: straight line, more or less a right angle Oblique: similar to spiral, one end receives torsion while the other is fixed Spiral: S-shaped separation, foot planted and body twisted in other direction Impacted: Fall from a height compressing the bone, need traction
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Less common types of fractures
Avulsion: Separation of bone fragment from cortex via pull of ligament or tendon
Blowout fracture: wall of the eye orbit
Serrated fracture: saw-tooth fracture line, may cause internal damage
Depressed fracture: in flat bones, fall or blunt trauma
Contrecoup fracture: opposite side from the point of trauma
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57. Factors that Affect Bone Strength
Strength of bone can be impacted by changes in shape and direction
Long bones with gradual changes are less prone to injury
Cylindrical and hollow nature of bones make them very strong - resistant to bending and twisting
Bones can be stressed or loaded to failure by tension, compression, bending, twisting and shearing
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QUESTION:
What is the difference between closed and open fracture? What is a Greenstick fracture? Where is the bone the “weakest”?
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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 (bones become weaker before stronger)
Early detection is difficult, bone scan is useful, x-ray is effective after several weeks, MRIs
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Typical causes (Mechanism) in sports 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
Signs and symptoms
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
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Question
What are some athletic mechanisms to stress fractures?
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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 years old
Classified by Salter-Harris into five types (see photo on next slide)
Apophyseal Injuries
Serve as sites of origin and insertion for muscles
Common avulsion conditions include Sever’s disease and Osgood-Schlatter’s disease
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Nerve Trauma
Reponses Include:
Hypoesthesia- diminished feeling
Hyperesthesia- increased feeling
Paresthesia- numbness or tingling
Neuropraxia: interruption in conduction of the impulse of the nerve fiber (last hours to months)
Neuritis: chronic inflammation of the nerve (minor to severe- paralysis)
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