Force Sense & Reactive Stiffening in Patients with Unstable - - PowerPoint PPT Presentation

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Force Sense & Reactive Stiffening in Patients with Unstable Ankles & Potential Copers Ala lan R. Ne Needle, edle, MS MS, ATC, C, CSCS CS C. Bu Buz Swan anik ik, , Ph PhD Ankle Sprains Most prevalent injury in physically

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SLIDE 1

Force Sense & Reactive Stiffening in Patients with Unstable Ankles & Potential Copers

Ala lan R. Ne Needle, edle, MS MS, ATC, C, CSCS CS

  • C. Bu

Buz Swan anik ik, , Ph PhD

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SLIDE 2

Ankle Sprains

  • Most prevalent injury in

physically active

– Hootman 2007, Waterman 2010

  • 850,000 annually in

emergency rooms

– Waterman 2010

  • Common long-term sequelae

include functional instability and ankle osteoarthritis

– Valderabanno 2006

http://1.bp.blogspot.com/_XmFW9XJVH68/TMhrE- bPcII/AAAAAAAAAQI/EsY0OWG7OD4/s1600/rondo.jpg

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SLIDE 3

Functional Ankle Instability

  • Sensations of “rolling” or “giving-

way” during normal activity

– Freeman 1965

  • Presents following 30-50% of

initial ankle sprains

– Konradsen 2002, Anandacoomarasamy 2005

  • Diagnosed using questionnaires

– No gold standard

http://4.bp.blogspot.com/_E1tEsdn7gHE/T QEygsLEExI/AAAAAAAAENI/RZwtUEh- GoU/s1600/scott_dunlap_trail_running_xte rra_2010.jpg

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SLIDE 4

Functional Ankle Instability

  • Original thought to be

secondary to damage to static restraints

  • Paradigms altered to

include damage to mechanoreceptors and loss of neuromuscular control

– Hertel 2002, Hiller 2010

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SLIDE 5

Problems

  • Mechanisms not established

– Inconsistent relationship between measures of stif iffne fness ss, proprioc priocepti eption

  • n, and insta

tabilit bility – Central versus peripheral?

Courtesy of Erik Wikstrom

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SLIDE 6

Ankle “Copers”

  • 50-70 percent of ankle sprain patients DO

NOT develop FAI

  • What is important for prevention of

subsequent sprains?

http://moblog.net/media/m/i/s/misteralfie/poor-dear-rose-broken- ankle.jpg

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SLIDE 7

Purpose

  • To understand the neuromechanical causes

behind ankle instability

  • To investigate the relationship between

laxity, stiffness, and proprioception (kinesthetic awareness, force sense) in healthy, previously injured, and unstable ankles.

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SLIDE 8

METHODS HODS

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SLIDE 9

Participants

  • 78 participants

– 22.3±3.1 yrs; 171.2±9.7 cm; 71.8±17.4 kg – Control (CON, n=20) – Copers (COP, n=19) – Functionally Unstable (UNS, n=19) – Sprainers (Mild Functional Instability) (SPR, n=20)

  • Determined using Cumberland Ankle Instability Tool with

History of Ankle Injury

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SLIDE 10

Instrumentation

  • Stiffness and Proprioception

Assessment Device (SPAD)

– Servomotor and torque sensor affixed to a foot plate – Force sense, Kinesthetic Awareness, Stiffness

  • Instrumented Ankle

Arthrometer (Blue Bay Research, Milton, FL)

– Mechanical laxity

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SLIDE 11

Methods –Laxity

  • Arthrometer affixed to foot

and shin

  • 3 Anterior-Posterior (AP)

translations to 125 N

  • 3 Inversion-Eversion (IE)

rotations to 4 Nm

  • Peak anterior displacement,

inversion rotation, and inversion-eversion range extracted

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SLIDE 12

Methods - Stiffness

  • Subjects seated on SPAD with hip flexed 120° and knee flexed

90°

  • 20° ankle supination perturbation

– 240°/sec, 3000°/sec2

  • Stiffness calculated as Δ Torque/Δ Rotation at short range, mid-

range, peak and total’

5 10 15 20 25 30 35 40 20 40 60 80 100 120 140 160

Positi ition

  • n (deg)

Tor

  • rque

e (in/lb) /lb)

Torque Position

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SLIDE 13
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SLIDE 14

Methods - Stiffness

Conditi dition

  • n

Instr structions uctions Pa Passiv sive e Stiffness fness (PS) “Remain completely relaxed throughout the entire perturbation” Ac Acti tive e Stiffness fness (AS) “Push out to [30% MVIC] prior to the move. When you feel the perturbation, hold that amount of contraction without pushing more or less.” Reacti ctive e Stiffness fness (RS) “Push out to [30% MVIC] prior to the move. When you feel the perturbation, resist it as hard and as fast as possible as if you are stopping your ankle from rolling in” Deacti ctivat ating ng Stiffness fness (DS) “Push out to [30% MVIC] prior to the move. When you feel the perturbation, turn off all your muscles and relax as quickly as possible.”

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SLIDE 15
  • Subjects seated on SPAD as previously descibed
  • Blindfolded with noise cancelling headphones
  • Ankle supinated at 0.5°/sec

– controlled accelerations (0.1, 1, 1000°/sec2)

  • Identify motion (det

etecti ection

  • n) OR recognize direction of motion (recogn
  • gnit

ition ion)

Methods – Kinesthesia

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SLIDE 16

Methods – Force Sense

  • Subjects seated on SPAD as previously described
  • Practice replicating 30% and 50% of MVC
  • Replicate force level 3 times w/out feedback
  • Relative Error, Variable Error, Coefficient of

Variation over 500ms match window of match

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SLIDE 17

Data Analysis

  • ANOVAs used to compare between groups

and across conditions

  • Pearson’s product-moment correlation

coefficients used to compare variables

  • Alpha set a priori less than 0.05
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SLIDE 18

RE RESU SULTS

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SLIDE 19

Results - Laxity

  • UNS displayed ↑ laxity

compared to CON & COP p=.024 & p=.007

  • No differences between

groups in inversion rotation (F=0.105, p=0.95)

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SLIDE 20

Results - Stiffness

  • Significant 3-way interaction of Group,

up, Condi

  • ndition,

tion, an and Ran ange ge

  • F=1.73, p=0.012
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SLIDE 21

Passive Stiffness

  • Short-range stiffness is affected in SPR
  • Total stiffness ↑ in COP
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SLIDE 22

Active Stiffness

  • Short-range stiffness ↓ in SPR
  • Mid-range & Total stiffness ↓ in UNS
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SLIDE 23

Reactive Stiffness

  • CON & COP has ↑ short-range and mid-range

stiffness than UNS

– SPR again has ↓ short-range

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SLIDE 24

Deactive Stiffness

  • Short-range stiffness ↓ in SPR
  • Mid-range & total stiffness ↓ in UNS
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SLIDE 25

Results - Stiffness

  • Short-range stiffness ↓ in SPR ankles

across conditions

  • Active & reactive stiffness ↓ in UNS

ankles

– Mid-range and total most affected

  • Short-range stiffness – parallel and

series elastic components of muscle

  • Mid-range stiffness – regulation of

reverse cross-bridge cycling

http://i.quizlet.com/i/f0LQLxzHd8obaSPf4I8e_g _m.jpg http://www- rohan.sdsu.edu/~jmahaffy/courses/f00/math1 22/lectures/images/actin.gif

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SLIDE 26

Results – Force Sense

  • COP and UNS had

better force sense compared to CON

– Lower variable error at 30% MVC

  • No other variable

significantly different between groups

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SLIDE 27

Results – Kinesthesia

  • No differences between groups or accelerations
  • Significant difference between instructions
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SLIDE 28

Results – Kinesthesia

  • Negatively correlated with inversion stiffness

– Short-range stiffness negatively correlated with detection & recognition of motion (r=-0.23 to -0.40, p<0.03) – Total stiffness of passively & reactively correlated with recognition of motion (r=-0.23 to -0.37, p<0.03) – Recognition errors positively correlated with short- range stiffness (r=-0.24 to -0.40, p<.03)

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SLIDE 29

DI DISC SCUSSION USSION

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SLIDE 30

Discussion

  • Both mechanical and sensory

alterations observed in functionally unstable ankles

  • Increased laxity observed in

UNS

– Mechanical instability may exist simultaneously or independently

  • f functional instability Delahunt et al

2010

– Laxity not correlated with measures of proprioception

http://tinypic.com/fcpsmb.jpg

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SLIDE 31

Stiffness Alterations

  • Altered stiffness regulation strategies
  • bserved in COP, UNS, and SPR
  • Patterns suggest mechanical alterations in

mild instability (short-range), and copers (total)

  • Unstable ankles demonstrate altered

stiffness regulation strategies

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SLIDE 32

Force Sense

  • Previous studies suggested

diminished force sense in unstable ankles Arnold et al 2010

  • COP & UNS have improved

ability to match loads compared to CON

  • Potential adaptation of

musculotendinous receptors following injury to capsuloligamentous tissue Needle 2010,

Needle 2011

http://jnnp.bmj.com/content/73/5/473/F1.large.jpg

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SLIDE 33

Kinesthesia

  • Increased short-range

stiffness appears beneficial for improving kinesthesia

  • Stiffness regulation may

be optimized based on mechanical properties Needle

2011

  • Recognition & Detection of

passive motion may test different components of the nervous system

http://www.bandhayoga.com/images/spindle_organ.jpg

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SLIDE 34

Future Directions

  • How are muscle activation strategies

affecting stiffness regulation?

  • Where in the nervous system are these

changes occurring?

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SLIDE 35

Thank You

  • C. Buz Swanik, PhD, ATC
  • Thomas Kaminski, PhD, ATC,

FNATA, FACSM

  • Jim Richards, PhD
  • Stephen Thomas, PhD, ATC
  • Laura Miller, MS, ATC
  • Kathy Liu, MS, ATC
  • Allison Kim, MS, ATC
  • Jenifer Halterman, MS, ATC
  • Craig Oates, ATC
  • Christina Shields, ATC
  • Yong Woo An, MS, ATC
  • Brittany Walls, ATC

For copies of slides, please contact me at aneedle@udel.edu