Injury Mechanisms and Classifications

Core Concepts in Athletic Training and TherapySusan Kay Hillman

Objectives Describe the anatomical reference position.

Use appropriate anatomical terminology to describe the location and position of a structure relative to the rest of the body.

Identify characteristics relating to the various stages of physical maturity.

Explain distinctiveness of the various types of musculoskeletal tissue.

Differentiate between elastic and plastic tissue properties.

Classify injuries as either acute or chronic based on the onset and duration of symp toms.

Define the common chronic inflammatory conditions, including signs and symptoms.

Define the various classifications of closed soft tissue wounds, including degrees of severity.

Define and classify closed and open wounds of the bone and joint articulations.

Classify nerve injuries according to mechanism, severity, and signs and symptoms.

Identify the classifications of open (exposed) wounds.

Introduction Proper reference to anatomical positions,

knowledge of injury terminology, and mechanisms essential for communicating effectively with other health care professionals

Assist you in documenting findings, convey history information during medical referrals, and collaborate with other healthcare professionals regarding care of your athlete

Anatomical Reference Terminology

All anatomical descriptions and references are based on standardized position of the body Anatomical Position

Allows us to reference specific body regions in relation to the body as a whole and one anatomical landmark to another Avoid confusion and misinterpretation of

your findings Can be standing or supine (on the spine)

Standing most common and easiest to visualize

Anatomical Reference Terminology

Anatomical position

Feet together, flat on the ground, toes facing forward

Legs and knees straight and in line with hip, torso and head, which are also straight and facing forward

Upper limbs positioned at persons side, with elbows straight

Shoulders rotated so palms are facing forward

Anatomical Reference Terminology

Once in anatomical position one can begin to refer to specific structure using various anatomical terms

Describe position of body parts with reference to other body parts or the body as a whole

Also synonyms reserved for particular body regions For example anterior=structure near front of

body, and anterior surface of hands is referred to as palmar or ventral

Anatomical Reference Terminology

From anatomical position can also define three anatomical planes of movement useful in describing postural positions, motions, and function of various muscles and joints Imaginary planes that separate the body into left and

right (sagittal or median), top and bottom (Transverse), and front and back (frontal or coronal) For example when nodding your head or flexing your

elbow this occurs in the sagittal plane Shaking your head no or rotating your palms so it is

facing backwards takes plane in the transverse Lifting arms out to the side occurs in the frontal

plane

Anatomical Reference Terminology

Patient positioning terminology important and helpful for understanding starting positions for various medical testing Supine (face up) and prone (face down)

refers to patient laying down Short sitting-patient sitting on edge of table

with legs hanging off the edge Long sitting patient sitting with legs out in

front of them with legs on the table or floor

Physical Maturity Classifications

Allows us to define stages of physical growth Normal anatomic and physiologic development from

infancy to older adulthood Infancy: (0-12 months) physical changes occur most

rapidly. Dependent neonate to a child learning motor skills such

as turning, sitting, crawling and walking Gain 3 x birth weight in this time

Childhood: (1-11 years) infancy to onset of puberty Steady growth and development Skeleton is immature with epiphyseal plates open to

allow bones to elongate 1-5 early childhood, 6-11 middle childhood

Physical Maturity Classifications

Adolescence: ( 11-13 through 18-20) Onset of puberty through full skeletal maturity Onset of Puberty marked by development of secondary sexual

characteristics Females: menarche, pubic hair, development of breast Males: Deepening of voice, pubic hair, and facial hair

Skeletal maturity marked by full closure (ossification) of epiphyseal plates and cessation of further growth in height Age at which bones complete ossification varies widely

from early teens to early 20’s Adulthood (18-40 years)

Indicate full skeletal maturity and development Bone and muscle mass increase through 25 to 30 years of age

after which mass levels off and then slowly declines

Middle adulthood (40-60 years) Gradual decline in strength coordination and

balance

Older adulthood (> 60 years) Spans rest of human beings life Accelerating decline in strength, coordination

and balance Highly individual depending on lifestyle,

activity, nutrition and disease

Injury Mechanisms

Foundation of body movements made up of several simple machines Levers, pulleys, and wedges among other more

complex systems Bodies capable of performing very intricate and

detailed work along with incredible feats of strength, power and endurance

However, body influenced by internal and external mechanical forces that can negatively affect performance

Important to understand musculoskeletal system, physical properties of the musculoskeletal tissue, internal and external mechanical forces that can cause injury

Injury Mechanisms

Musculoskeletal Tissue

Five tissue types Categorized by Soft and Skeletal Tissue

Soft tissue Muscles, tendons, ligaments, and

cartilage

Skeletal Tissue Bone

Injury Mechanisms

Musculoskeletal Tissue Properties Degree and location of injury often

determined by tissue strength Musculoskeletal tissue has elastic and plastic

(inelastic) properties. Elastic properties manifested as response

to loading, stress or mechanical forces that cause stretching or deformation of tissue After stress is removed tissue returns to

relatively normal state

Injury Mechanisms

Plastic Properties manifested at end range of elastic properties rendering tissue unable to return to normal

state

Tissue retains some amount of deformation due to structural injury

• Yield point: determined by specific amount or level of stress

• Example: stretching a rubber band. Point at which it breaks is considered yield point

• Enough force to eliminate elastic property recovery and cause rubber band to undergo

plastic deformation

Injury Mechanisms

Athletic injuries occur much the same way Tissue stress determined by amount of

mechanical force divided by total area affected If tissue stress, is low enough that tissue

remains in elastic property zone patient may only occur minor injury or none at all

If stress in high enough to force tissue to plastic property zone injury severity and tissue damage more significant

Injury Mechanisms

Individuals and individual tissue have an ability to respond to and resist a certain amount of load or stress before deformation As load or stress increases the potential for tissue

deformation also increases Type of force applied, along with the surface area

acted upon by the force , also affects the injury Given same velocity localized force can result in

substantially greater tissue damage than the dame force applied over a broader surface area

Injury Mechanisms

Tissue damage may be the result: unpredictable accident or injury Overuse Overload Poor posture Skeletal immaturity Lack of conditioning Improper mechanics Fatigue Inflexibility Muscle imbalance Genetics

Mechanical Forces

Stress or load applied to the body to cause injury or tissue deformation is a result of 1 of 5 types of mechanical force Excessive compression

Squeezing or condensing of tissue due to external forces applied directly opposite of each other Bruises (contusions) Crushing injuries (compression fractures) Pinching Injuries due to direct impact

Mechanical Forces

Shear Forces that cause tissue to “slide” over

adjoining surfaces or structures in a parallel fashion Brain injuries Tibiofemoral translation injuries such as

ACL and PCL injuries Blisters Lumbar spine injuries

Mechanical Forces

Torsion Twisting mechanism that causes rotation

along long axis or fixed point Opposite ends of tissue are rotated in

opposite directions Example: Body rotating over Foot fixed or

lower leg Occurs to bones and ligaments

Tension Stretching or lengthening of musculoskeletal

tissue due to stress or strain Caused by pulling or drawing apart Pull of tissue in opposite direction causes

tissue in between to stretch Muscle strains or ruptures commonly

caused by tension within the musculotendinous unit Where muscle makes transition into

tendon

• Weak part of muscle

Mechanical Forces

Bending Deformation of tissue into convex or concave

shapes due to axial loading Forces acting in opposite directions at

different ends of tissue Or significant impact to middle of tissue

while the ends are stable Convex surface undergoes tensile forces

while concave surface undergoes compression forces Example: Fibula fracture with direct

blow

Mechanical Forces

Mechanical forces are not isolated Usually 2 or more mechanical forces acting

on tissue at one time Complex mechanisms and forces that come

together to cause injury Example: Lateral blow to knee with foot

planted Compressive forces to lateral knee,

bending force to medial knee, shear and tension forces to middle of knee

Valgus force: toward midline Varrus Force: Away from midline

Time Classification Relating to Mechanism of Injury

Acute Injuries Conditions that have sudden onset, short

duration, and occur via mechanical forces that exceed elastic properties causing tissue deformation

Single traumatic event: blunt force trauma, dynamic overload of muscle, tendon, joint capsule or ligamentous tissue

Time Classification Relating to Mechanism

of Injury Chronic Injuries

Gradual onset, prolonged duration, and occur as a result of accumulation of minor insults or repetitive stresses

Exact mechanism not often known Overuse, accumulative microtrauma, repetitive

overloading, abnormal friction that is greater than body's ability to heal and recover before additional stress is added

“too much, too soon, too often” Often more difficult to treat overuse (chronic)

injuries than acute injuries

Injury Classifications

Sign: finding that is observable or that can be objectively measured Swelling, discoloration, deformity Crepitus: crackling, grating, or grinding

sensation

Symptom: subjective complaint or an abnormal sensation the patient describes but cannot be directly observed Pain, nausea, altered sensation, fatigue

Injury Classifications Closed (Unexposed) Wounds: Injury that

does not disrupt surface of skin Contusion or bruise

Signs: swelling discoloration and deformity

Compression of soft tissue due to direct blow or impact

Damage to small capillaries in tissue Local bleeding (hemorrhage), causing

ecchymosis (discoloration of tissue), may be immediate or delayed

Contusion Severity

• First degree: superficial damage, minimal swelling, localized tenderness, no limitations to strength or ROM

• Second Degree: Increased pain and hemorrhage, increased area and depth of tissue damage, mild to moderate limitation sin ROM and muscle function or both

• Third degree: severe tissue compression, severe pain, significant hemorrhage and development of hematoma• Significant limitations in ROM and muscle function• Suspect damage to deeper structures such as none

Closed Wounds

Sprains: injury to ligaments or capsular structure Ligaments attach bone to bone

Injury occurs when 2 bones separate or go beyond normal ROM

First Degree: mild overstretching Mild pain and tenderness, little or no disability AROM and PROM not limited but some pain at

end range Firm definitive end point (feel) Degree of swelling and discoloration not great

indicator of severity

Sprain Severity

Second Degree: Further stretching and partial disruption or macro tearing of ligament Moderate to sever pain Point tenderness Eccyhmosis Swelling ROM and normal function limited secondary to pain

and swelling Stress testing shows instability or laxity but still feel

an end point

Sprain severity

Third Degree: Complete disruption or rupture or loss of ligament integrity Associated with feeling or sound of a pop Immediate pain and disability Rapid swelling. Eccyhmosis and loss of function Stress test shows moderate to severe instability with

no firm end point “ soft or mushy” Can be deceiving because Rom and stress testing less

painful because ligament not intact

Strains

Stretching or tearing of muscle or tendon Violent, forceful contraction or

overstretching Fatigue, lack of warm up muscle strength

imbalance, and dyssynchrony

Strain Severity

First Degree: overstretching and micro tearing of muscle or tendon. No gross fiber disruption Mild pain and tenderness Typically full AROM and PROM Pain with resisted muscle contraction

Strain Severity

Second Degree: further stretching or partial tearing of muscle or tendon fibers Immediate pain, localized tenderness and

disability Varying degrees of swelling, eccyhmosis, and

decreased ROM and strength Pain with active muscle contraction and

passive muscle stretch May have palpable defect

Strain Severity

Third Degree: Muscle or tendon completely ruptured Audible pop Immediate pain and loss of function Palpable defect on superficial muscles Muscle hemorrhage and diffuse swelling ROM and strength may or may not be

affected or painful

Injury Classifications Open (Exposed) Wounds

Injuries that involve disruption of the skin Caused by friction or blunt or sharp trauma Susceptible to infection

Monitor for pus increased pain, redness, swelling, heat and red streaks running from wound to trunk If signs of infection are present refer to

medical professional

Injury Classifications

Bone and Joint Injuries Closed Fractures: disruption in continuity of bone without disruption

of skin surface Traumatic (Acute): immediate pain, rapid swelling, bony

tenderness, false joint, crepitus, deformity Displaced fracture concern with secondary injury

• Evaluate neurovascular status distal to fracture site

Stress Fracture: S & S not always as obvious Onset of pain is gradual Pain or deep ache may be first noticeable during activity and

subside with rest, • progresses to more constant pain if offending

activity continues Swelling is minimal and localized tenderness over fracture site

Bone and Joint Injuries Epiphyseal Injury

Disruption of epiphysis or epiphyseal plate (growth plate) Can cause premature closing and growth abnormalities

Dislocation Complete disassociation of 2 joint surfaces Forces cause joint to exceed passed its normal ROM Severe Stretching or complete disruption of joint capsule

and supporting ligaments Pain swelling, loss of function, deformity

Subluxation Incomplete disassociation of 2 joint surfaces Disability, pain, selling and joint instability varies Often history of sensation of joint slipping or giving out

Injury ClassificationsNerve Injuries

Compression or tensioning of neural structure

Laceration of nerve can occur secondary to fracture, dislocation, penetrating trauma

Anesthesia: no sensation

Parathesia: tingling, burning, numbness

Hyperesthesia: hypersensitivity

Paralysis: complete loss of muscle function

Nerve Injuries Neuropraxia: transient and reversible

loss of nerve function

Axontmesis: partial disruption of nerve Considerable atrophy and

weakness due to prolonged healing 2 weeks to a year

Neurotmesis: most severe nerve injury, complete severance of the nerve

Neuralgia: achiness or pain along distribution of nerve secondary to irritation or inflammation

Neuroma: thickening of a nerve or “nerve tumor”, secondary to chronic irritation or inflammation