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

• Acceleration or change in velocity

• Deformation or change in shape

• • Greater stiffness of material = less likelihood that deformation will be seen

• • Greater elasticity of material = more likelihood that deformation will be temporary

5. Force

When tissues exposed to force, 2 factors determine whether or not injury will occur

• Size or magnitude of force

• Material properties of involved tissues

6. Force

Load deformation curve

With small loads, response of tissue is elastic

• When load removed, material returns to normal shape and size

• 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

• When load removed, some amount of deformation will remain

• 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

• Axial loading producing a crushing/squeezing effect is called compressive force

• 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

• Magnitude of stress produced by force application also factors into injury mechanism

• Stress is force divided by surface area over which the force is applied

• When given force distributed over large area, resulting stress is less than if force were concentrated over smaller area and vice versa

• High magnitude of stress, rather than high magnitude of force, tends to result in injury to tissue

11. Stress 12. Force

Strain

• Amount of deformation a structure undergoes in response to an applied force

• Compressive forces produce shortening and widening of structure

• Tensile forces produce lengthening and narrowing of structure

• Shear forces result in internal changes in structure

• 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

• 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

• 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

• Shear injuries occurring when skin scraped, usually in one direction, against a rough surface

Blisters

• Caused by repeated applications of shear forces in one or more directions with formation of fluid pocket between dermis and epidermis

Incisions

• Clean cut produced by application of tensile force to skin as its stretched along a sharp edge

17. Skin Injuries

Lacerations

• Irregular tear in skin typically resulting from a combination of tension and shear forces

Avulsions

• Severe laceration resulting in complete separation of skin from underlying tissue

Punctures

• 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

• Mild little or no ROM restriction

• Moderate noticeable reduction in ROM

• 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)

• Microtrauma with minimal associated symptoms

Second degree (moderate)

• Partial tearing of tissue, detectable weakness and joint instability

Third degree (severe)

• 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

• Inflammation of tendon itself little blood supply

• Associated with degenerative changes in tendon (tendinosis)

Tenosynovitis

• Inflammation of tendon sheath highly vascular

• If acute, often accompanied by crepitus and swelling

• If chronic, of presents with nodule formation in sheath

24. Overuse Injuries

Typically classified in four stages

• Stage 1: pain after activity only

• Stage 2: pain during activity, does not restrict performance

• Stage 3: pain during activity, restricts performance

• 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

• Broken bone portion driven inward most common on flat bones of skull

Transverse

• Break in straight line across axis of bone

Comminuted

• Bone fragments into several pieces

Oblique

• Break diagonally across axis of bone

29. Fracture Types

Spiral

• S-shaped fracture from torsion forces

Greenstick

• Incomplete fractures children (like green stick)

Avulsion

• Bone fragment pulled off by attached ligament or tendon

Impacted

• Bone driven into another bone causing injury

30. Fracture Types 31. Fracture Types

Stress fractures (aka fatigue fractures)

• From repeated low-magnitude forces (overuse injury)

• Worsen over time if untreated

• Begin as small disruption in continuity of outer layer of bone and can progress to through fracture with or without displacement

• Most common in metatarsals, tibia, femoral neck, pubis bone, pars interarticularis of spine segments

32. Fracture Types

Epiphyseal injuries (Salter classifications)

• Type I: complete separation of epiphysis from metaphysis with no fracture to bone

• Type II: separation of epiphysis and a small portion of the metaphysis

• Type III: fracture of the epiphysis

• Type IV: fracture of a part of the epiphysis and metaphysis

• 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

• Direct mechanical force on nerve tissue

• Indirect pressure from swelling in associated area

36. Tensile Injury Grades

Grade I neuropraxia

• Temporary loss of sensation/motor function without axon disruption

• Typically resolves in a few days to a few weeks

Grade II axonotmesis

• Significant motor and mild sensory function loss from axon disruption

• Typically lasts at least a couple of weeks

Grade III neurotmesis

• 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

• Altered sensation of nerve

Hyperesthesia

• Heightened sensitivity of nerve

Paresthesia

• Numbness, prickling, tingling sensations

Neuralgia

• Chronic pain along nerve distribution/path secondary to irritation and/or inflammation

39. Terminology 40. Anatomic Position 41. Planes of the Body

Sagittal

• Separates into left and right segments

Frontal/coronal

• Separates into anterior and posterior segments

Transverse

• 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