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Module 6

Effects Produced by Spinal Manipulation (Herzog Chapter 5)

Biomechanics of Gait (Nordin Chapter 18 & web downloads)

Biomechanics of the Shoulder (Nordin Chapter 12)

Biomechanics (TECH 71613)

James W. DeVocht, DC, PhD

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Force-time history of chiropractic adjustment

Herzog Fig 5-1

100 – 200 msec for most manual adjustments

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Measurable responses elicited by chiropractic adjustments

Herzog page 195

1. Mechanical responses

2. Neuromuscular reflex responses

3. Physiologic responses

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1. Mechanical Response

Herzog Fig 5-4

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Mechanical Response as a function of timeof T10 & T12 for thrust on transverse process

of T11 in an unembalmed, post rigor, human cadaver

Herzog Fig 5-5

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2. Neuromuscular Reflex Responses (reflex pathway for muscle spindle)

Herzog Fig 5-6

Ia

Can be inhibitory or excitatory

7Herzog Fig 5-7

Spindle reflex response

Capsule mechanoreceptor

response

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EMG Reflex Response

Herzog Fig 5-8

50 – 200 msec

t: delay from beginning of thrust to beginning of EMG responseResponse typically lasts 100-400 msec, then disappears

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Simultaneous Responses to SM

Herzog Fig 5-9 (Manual Thrust on T4) Herzog Fig 5-10 (Activator Thrust on T6)VAG: cavitation response LAT: latissimus dorsiT6 & T4: levels of spinalis

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Time Delays Regarding EMG values

Herzog Fig 5-12

t: thrust onset to 1st EMG

t1: 1st EMG to onset of muscle force

t2: muscle force onset to peak muscle force

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Release of muscle spasm

Herzog Fig 5-13

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Activator Adjusting Instrument with accelerometer attached

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Taking surface EMG data during Activator treatment

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Release of muscle spasm

DeVocht, 2003JMPT, 26(7), 421-425

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EMG Data from Pre-Post Treatment

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Can be generated by fast or slow thrust(more likely with fast thrust)

Herzog page 204

3. Physiologic effect produced during SM:Articular noise (audible release)

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Schematic representation of force-displacement curve (includes audible release)

Herzog Fig 5-13

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Model of Joint Cavitation

Brodeur 1995, Fig 8JMPT, 18:3, p 160

A: Normal joint with no external loads

B: Initial distention, ligament invaginates

C: Tensile force up, snaps ligament back which now has some slack in it

D: Volume has increased, bubbles form

E: Ligament tightens as tensile force continues

F: Stable situation with increased volume and joint space

http://www.youtube.com/watch?v=LxtAeGtL9SE boiling:

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Joint separation before & after cavitation

Brodeur 1995 Fig 4JMPT, 18:3, p 157

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Is an audible release necessary?

Herzog page 206

Sound or feel of cavitation often used as indication that the adjustment was “successful”

Many chiropractors will repeat an adjustment if

there was no discernable “release”

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Force-time histories of 2 attempts for cavitation

Herzog Fig 5-15

1st attempt: dotted line2nd attempt: solid line

- 2nd attempt usually has higher peak force

- Usually has higher rate of force application

- Often does result in cavitation

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Recent studies suggest that there is little if any clinical significance concerning whether or not an audible pop occurs in connection with a spinal manipulation

Flynn 2006JMPT 29:1 p 44

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forefoot hindfoot(talus &calcaneus)

midfoot“instep”

Transverse Divisions of the Foot

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Lateral Foot - calcaneus - cuboid - metatarsals & phalanges of toes 4 & 5

Medial Foot - talus - navicular - cuneiforms - metatarsals & phalanges of toes 1, 2, & 3

Longitudinal Divisions of the Foot

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Ankle Joint: Pure Hingecomprised of tibia, fibula, & talus

mortise joint: rectangular space between medial & lateral malleoli

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Full Gait Cycle, or Stride(refers to movement of one leg)

Stance phase

- Foot in contact with floor

- 60% of cycle when walking

Swing phase (40% when walking)

- Foot has no contact with the floor

- 40% of cycle when walking

Nordin page 440

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Sequence of Gait Cycle (walking)

Nordin Fig 18-1

TO: toe off (left & right) HC: heel contact (left & right)

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Stance Phase has 6 Parts

1. Initial contact (hind foot touches floor)

2. Loading (sole contact floor, body weight shifts)

3. Midstance (tibia rotates over talus)

4. Terminal stance (weight shifts from hind & mid to forefoot)

5. Pre-swing (weight shifts to contralateral leg)

6. Toe off (forefoot leaves the floor)

Nordin page 440-1

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Center of pressure changes during stance phase

from www.drpribut.com/sports/spgait.html

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Swing Phase has 3 parts

1. Initial swing

(from toe off until opposite stance foot)

2. Mid-swing

(ends when tibia is vertical)

3. Terminal swing

(ends when heel contacts the floor)

Nordin page 441

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Total vertical displacement about 5 cmTotal medial-lateral displacement about 4 cm

Neumann Fig 15-13

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Spatial sequence of gait cycle (running)

Nordin Fig 18-2

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Windlass Effect

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Talofibular & Calcaneofibular Ligaments

lateral viewcommonly injured

http://video.google.com/videoplay?docid=-4399476076864988236&q=broken+ankle+tennis&total=9&start=0&num=100&so=0&type=search&plindex=5 tennis accident (35 sec)

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Biomechanics of the Shoulder(involves 4 articulations)

Nordin Fig 12-1

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Sternoclavicular Joint

Nordin Fig 12-4

Articulation with first rib

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Movements of the Sternoclavicular

Joint

Nordin Fig 12-5

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Acromioclavicular Joint

Nordin Fig 12-6

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Glenohumeral Joint

Nordin Fig 12-8

Tendon of the long headof the biceps lies downin the bicipital groove

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Glenoid Labrum(provides 50% of depth of glenohumural joint)

Nordin Fig 12-10

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SLAP lesion(Superior Labrum from A – P)

Nordin Fig 12-11

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Scapulothoracic Articulation

Nordin Fig 12-13

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Musculature Between Scapula & Thorax(stabilizes scapula – prevents winging)

Nordin Fig 12-14http://www.youtube.com/watch?v=HepHiQOsT-E

http://www.youtube.com/watch?v=814TZ4WUEKk

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Lateral bending of spine enhancesability to position upper extremity

Nordin Fig 12-15

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Rotator Cuff Musculature(4 muscles)

Nordin Fig 12-17

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Primary motions of the shoulder

Nordin Fig 12-2

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Optimal motion of the shoulder(in plane of long axis of the scapula)

Nordin Fig 12-3

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Forward elevation or abduction of armrequires synchronous rotation of scapula

Nordin Fig 12-22

http://www.youtube.com/watch?v=hGOTf3Xl6Qs&mode=related&search=