Transcript tear to the muscle

Richard V. Baratta, Ph.D., P.E.
The Subro
Grapevine
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Basics of tissue biomechanics
Basics of injury causation
Injury biomechanics
Situations & their injury potential
Reading medical reports regarding injuries
Warning! Graphic images...
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Anterior: Forward
Posterior: Rear
Medial: Towards the middle
Lateral: Towards the side
Proximal: Close to the head
Distal: Further from the head
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Bone
Ligament
Tendon
Muscle
Other soft tissues
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Hard, mineralized
tissue
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Cortical – outside, hard
Medullary – inside,
“spongy”
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Stronger along the lines
where forces are
naturally applied
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If you read “spiral fracture”
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If you read “transverse fracture”
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Think bending
If you read “oblique fracture”
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Think torsion
Think axial force
If you read “comminuted”
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Think high energy/velocity
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Tough rope-like
connective tissue
between 2 bones
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Can tear in the middle
(midsubstance tear)
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Partial or complete
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Can pull off from a
bone (avulsion)
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Contractile
Made up of sliding
fibers
Create greatest force
when forcefully
stretched while
contracting
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Most tears happen
when contracts but is
still being lengthened
Most tears happen at
the junction between
muscle and tendon
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Connect muscle to
bone
Structure similar to
ligaments
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Can tear
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Partial or complete
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Can tear
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Partial or complete
Can avulse
Takes great force to tear
or avulse normal tendon
Happens when its muscle
lengthens against a
contraction
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Soft tissues surrounding
joints
Thinner than ligaments
Contain joint fluid
within the joint
Tear with dislocations
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Muscle
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Strain
Tear
Rupture
Most often, muscle tears
occur at junction
between muscle and
tendon
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Ligament
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Sprain
Partial Tear
Complete Tear
Joint Dislocation
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Skeletal System Anatomy
Upper Extremity
Lower Extremity
Spine
Head
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Radius, Ulna, Carpal
bones
Ligaments
Tendons
Carpal Tunnel
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Carpal Tunnel
Syndrome “cumulative
trauma disorder”
Sprains
Fractures -
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Tennis Elbow (overuse)
Golfer’s Elbow (overuse)
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Fractures
Medial Ligaments
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Ball and Socket joint
Head of Humerus (ball)
Glenoid (socket)
Scapula
Acromion
Clavicle
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P-A force on shoulder
or humerus
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Head of humerus comes
forward (anterior) out
of the socket
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Fairly uncommon (5%)
A-P force on shoulder or
humerus
Seizures
Electrocution
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Downwards force on
shoulder
Separates clavicle
and rest of shoulder
Falls
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Muscles that rotate the upper
arm
Injuries are to the tendons,
not muscle fibers
Overuse or violent humerus
external rotation
Depends on position
(abduction)
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Femur, Tibia, Patella
Anterior and Posterior
Cruciate Ligaments
Medial and Lateral
Colateral Ligaments
Meniscus
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ACL prevents the tibia
from moving forward
on the femur and from
rotating inwards
Cutting
Hyperextension
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Can be injured when a
force tries bend the
knee in a lateral
direction
The ligament getting
stretched is the one that
gets injured
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Segment Curvatures
Segment Mobilities
Vertebral Body Sizes
Atlanto-Axial Joint
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Viscoelastic (like silly putty)
On high speed impacts, vertebral fractures are
more likely than disc ruptures!
The only way to
“pop a disc” on a single
event is combined
compression and
bending (torsion helps)
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Injury pattern depends on mechanics
Danger of injuring spinal cord
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High Speed auto
accidents
Often fatal
“Raccoon eyes”
when not fatal
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Concussion – No structural damage, but some
temporary loss of function
Contusion – More serious, bruising of the brain
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Subdural hematoma
Subarachnoid
hemorrhage
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Direct impacts to the
skull may injure
brain on the same
side, opposite side, or
both sides of where
the force is applied
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One of the most highly
stressed joints in the
body
Direct impact to the jaw
or joint
TMJ syndrome –
chronic!
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Mechanism of injury
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Direct Contact
Exceeding range of motion
Indirect forces
Acceleration (brain injuries)
Loads sustained by tissue
Tissue tolerance to loads
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Pre existing conditions (tissue attenuation)
Assessment of Situation Mechanics
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Witness statements
Site inspection (regulations, standards, laws)
Other information (police reports)
Modeling
Review of Medical Records
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Determination of claimed injuries
Pre-existing conditions
Analysis
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Correlation between claimed injuries and event mechanics
Differentiate acute and chronic conditions
Assess effect of pre-existing conditions
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Arrange in understandable terms
Oral report
Written report
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Letter report
Formal report
Litigation support: Posters, demonstrative evidence,
video animation
Coordination with attorney
Testimony
True?
False?
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“Airbag blew up and
flung my arm back and
out”
“Bus hit a pothole and
steering wheel jerked
left”
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“Fell back onto my
outstretched hand”
“In the accident
(sideswipe)”
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X
Dx: Lumbar disc
herniation with
osteophytes
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“Years of heavy
labor”
“In the accident (low
speed rear end
collision)”
X
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“In the accident (low
speed rear end
collision)”
“Airbag blew up and
hit me in the jaw”
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26 y/o woman sustained fatal slip and fall injury in bathroom
Cause of death: brain hemorrhage due to head hitting toilet rim
Reported injuries: 2 scalp lacerations, contusion on right side of
neck, anterior iliac spines
Non-reported injuries (evident photographically)
Abrasions on left side of neck (3), chin, both shoulders
 Cut lip
 2 parallel linear marks on back
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X
Accidental slip and fall?