kin 188 mechanisms and types of injuries
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- 1. KIN 188 Prevention and Care of Athletic Injuries Mechanisms and Types of Injuries Terminology
2. Introduction
- Injury mechanisms
- Soft tissue injuries
- Bone injuries
- Nerve injuries
3. Injury Mechanisms
- Force and its effects
- Torque and its effects
4. Force
- Force is a push or pull acting on the body
- There are 2 potential effects of force application
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- Acceleration or change in velocity
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- Deformation or change in shape
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- Greater stiffness of material = less likelihood that deformation will be seen
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- Greater elasticity of material = more likelihood that deformation will be temporary
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5. Force
- When tissues exposed to force, 2 factors determine whether or not injury will occur
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- Size or magnitude of force
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- Material properties of involved tissues
6. Force
- Load deformation curve
- With small loads, response of tissue is elastic
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- When load removed, material returns to normal shape and size
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- Within elastic region, greater material stiffness leads to a steeper slope of the line
- With higher loads (exceeding yield point of material), response is plastic
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- When load removed, some amount of deformation will remain
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- Loads exceeding ultimate failure point of material result in mechanical failure of the tissue
7. Load-Deformation Curve 8. Force
- Direction of force application also has injury implication potential
- Many tissues are anisotropic better able to resist force from certain directions that others
- Force acting along long axis of structure is axial force
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- Axial loading producing a crushing/squeezing effect is called compressive force
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- Axial loading opposite compressive forces is called tensile force
- Force acting parallel to plane passing through structure is shear force
9. Compression, Tension and Shear 10. Force
- Stress
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- Magnitude of stress produced by force application also factors into injury mechanism
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- Stress is force divided by surface area over which the force is applied
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- When given force distributed over large area, resulting stress is less than if force were concentrated over smaller area and vice versa
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- High magnitude of stress, rather than high magnitude of force, tends to result in injury to tissue
11. Stress 12. Force
- Strain
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- Amount of deformation a structure undergoes in response to an applied force
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- Compressive forces produce shortening and widening of structure
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- Tensile forces produce lengthening and narrowing of structure
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- Shear forces result in internal changes in structure
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- Ultimate strength of tissues determines amount of strain a structure can withstand before being injured
13. Torque
- Generically thought of as a rotary force
- Excessive torque in the body can produce injury
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- Simultaneous application of forces from opposite directions at different points along a structure generates torque known as bending moment compression on one side and tension on the other
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- Application of torque about the long axis of a structure causes torsion (twisting) which results in shear forces throughout the structure
14. Torque 15. Soft Tissue Injuries
- Skin injuries
- Contusions
- Strains
- Sprains
- Cramps/spasms
- Myositis/fasciitis
- Tendinitis and tenosynovitis
- Myositis ossificans
- Bursitis
16. Skin Injuries
- Abrasions
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- Shear injuries occurring when skin scraped, usually in one direction, against a rough surface
- Blisters
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- Caused by repeated applications of shear forces in one or more directions with formation of fluid pocket between dermis and epidermis
- Incisions
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- Clean cut produced by application of tensile force to skin as its stretched along a sharp edge
17. Skin Injuries
- Lacerations
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- Irregular tear in skin typically resulting from a combination of tension and shear forces
- Avulsions
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- Severe laceration resulting in complete separation of skin from underlying tissue
- Punctures
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- Results when sharp, cylindrical object penetrates the skin with tensile loading
18. Contusions
- Commonly referred to as bruises
- Result from direct compressive forces
- Severity based upon area and depth over which blood vessels are ruptured
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- Mild little or no ROM restriction
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- Moderate noticeable reduction in ROM
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- Severe may rupture associated fascia causing muscle tissue to protrude from injured area
- Ecchymosis - discoloration
- Hematoma hard mass composed of blood and dead tissue at site of trauma
19. Strains/Sprains
- Strains occur to muscles and tendons
- Sprains occur to ligaments and joint capsules
- Typically occur from application of abnormally high tensile forces that damages the tissue
- Most susceptible area of muscle/tendon injury is at/near musculotendinous junction
- Most susceptible area of ligament/joint capsule is mid-substance (strongest near bony attachments)
20. Strains/Sprains
- Strains and sprains categorized as first, second or third degree injuries
- First degree (mild)
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- Microtrauma with minimal associated symptoms
- Second degree (moderate)
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- Partial tearing of tissue, detectable weakness and joint instability
- Third degree (severe)
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- Complete rupture of tissue, loss of ROM and joint stability
21. Cramps/Spasms
- Painful, involuntary muscle contractions
- Cramps appear to be brought on by biochemical imbalance and/or muscle fatigue
- Spasms can be caused by biochemical action or secondary to trauma (natural splinting mechanism)
22. Myositis/Fasciitis
- Inflammation of muscle connective tissue (myositis) or inflammation of sheaths of fascia surrounding portions of muscle (fasciitis)
- Develop over time from repeated stresses that irritate those tissues
23. Tendinitis/Tenosynovitis
- Tendinitis
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- Inflammation of tendon itself little blood supply
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- Associated with degenerative changes in tendon (tendinosis)
- Tenosynovitis
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- Inflammation of tendon sheath highly vascular
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- If acute, often accompanied by crepitus and swelling
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- If chronic, of presents with nodule formation in sheath
24. Overuse Injuries
- Typically classified in four stages
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- Stage 1: pain after activity only
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- Stage 2: pain during activity, does not restrict performance
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- Stage 3: pain during activity, restricts performance
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- Stage 4: chronic, unremitting pain, even at rest
25. Myositis Ossificans
- Accumulation of mineral deposits in muscle (ectopic calcification) secondary to prolonged chronic inflammation
- If occurs in tendons, referred to as calcific tendinitis
- Common site is quadriceps muscle group secondary to moderate or severe contusion
- Hardened mass often palpable and can be visualized on x-ray after ~3 weeks
26. Bursitis
- Irritation of fluid-filled sacs that serve to reduce friction in the tissues surrounding joints
- May be associated with single traumatic event or secondary to repeated applications of stress with overuse conditions
- Common to olecranon area (elbow) and pre-patellar area (knee)
27. Bone Injuries
- Fracture disruption in continuity of a bone
- Type of fracture depends upon type of mechanical loading that caused it as well as on health of bone at the time of injury
- Closed fracture bone ends remain intact within surrounding soft tissue
- Open/compound fracture one or both bone ends protrudes from the skin
28. Fracture Types
- Depressed
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- Broken bone portion driven inward most common on flat bones of skull
- Transverse
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- Break in straight line across axis of bone
- Comminuted
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- Bone fragments into several pieces
- Oblique
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- Break diagonally across axis of bone
29. Fracture Types
- Spiral
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- S-shaped fracture from torsion forces
- Greenstick
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- Incomplete fractures children (like green stick)
- Avulsion
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- Bone fragment pulled off by attached ligament or tendon
- Impacted
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- Bone driven into another bone causing injury
30. Fracture Types 31. Fracture Types
- Stress fractures (aka fatigue fractures)
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- From repeated low-magnitude forces (overuse injury)
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- Worsen over time if untreated
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- Begin as small disruption in continuity of outer layer of bone and can progress to through fracture with or without displacement
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- Most common in metatarsals, tibia, femoral neck, pubis bone, pars interarticularis of spine segments
32. Fracture Types
- Epiphyseal injuries (Salter classifications)
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- Type I: complete separation of epiphysis from metaphysis with no fracture to bone
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- Type II: separation of epiphysis and a small portion of the metaphysis
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- Type III: fracture of the epiphysis
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- Type IV: fracture of a part of the epiphysis and metaphysis
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- Type V: compression of the epiphysis without fracture resulting in compromised epiphyseal function
33. Epiphyseal Fractures 34. Nerve Injuries
- Tension vs. compression
- Tensile injury grades
- Compression considerations
- Symptoms of nerve injuries
35. Tension vs. Compression
- Tensile nerve injuries typically associated with high-speed impacts/collisions in contact sports
- Nerve roots particularly susceptible to tensile forces cervical spine/brachial plexus stingers
- Compressive forces pinch on nerves
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- Direct mechanical force on nerve tissue
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- Indirect pressure from swelling in associated area
36. Tensile Injury Grades
- Grade I neuropraxia
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- Temporary loss of sensation/motor function without axon disruption
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- Typically resolves in a few days to a few weeks
- Grade II axonotmesis
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- Significant motor and mild sensory function loss from axon disruption
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- Typically lasts at least a couple of weeks
- Grade III neurotmesis
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- Complete rupture of nerve tissue with associated motor and sensory deficits that are typically permanent
37. Compression Considerations
- Severity of nerve compression injury dependent upon magnitude and duration of loading and on whether the applied compression is direct or indirect
- Nerve function highly dependent upon oxygen, so associated vascular injury caused by compressive injury results in further damage to the nerve
38. Symptoms of Nerve Injuries
- Hypoesthesia
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- Altered sensation of nerve
- Hyperesthesia
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- Heightened sensitivity of nerve
- Paresthesia
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- Numbness, prickling, tingling sensations
- Neuralgia
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- Chronic pain along nerve distribution/path secondary to irritation and/or inflammation
39. Terminology 40. Anatomic Position 41. Planes of the Body
- Sagittal
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- Separates into left and right segments
- Frontal/coronal
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- Separates into anterior and posterior segments
- Transverse
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- Separates into superior and inferior segments
42. Terminology
- Anterior toward front of body
- Posterior toward back/rear of body
- Superior (cephal) toward head
- Inferior (caudal) toward tail
- Proximal closer to trunk
- Distal further from trunk
43. Terminology
- Medial toward midline of body
- Lateral away from midline of body
- Abduction movement away from midline
- Adduction movement toward midline
- Pronation foot: lowering medial arch, hand: turning palm down
- Supination foot: raising medial arch, hand: turning palm up
44. Terminology
- Flexion to bend (joint angle increases)
- Extension to extend (joint angle decreases)
- Internal rotation rotary movement toward midline
- External rotation rotary movement away from midline
- Varus distal segment of body part toward midline
- Valgus distal segment of body part away from midline