anatomy of instability

8/20/2019 Anatomy of Instability

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Anatomy of G-H Joint

Stability & Instability

Glenohumeral jointCapsule/Ligaments/Glenoid

Instability/Impingement/RC tears


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Components of Stability

Concept: Considerable individual

variations in capsuloligamentous

anatomy, inherent shoulder laxityLaxity: Asymptomatic passive translation

of the humeral head on the glenoid

Instability: Pathologic condition manifest

as pain in association with excessive G!

movement"


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Articular Surface

GeometryGlenoid surface issmall articular surfacearea, #oll$%pin$%lide

important!umeral head toglenoid &:'

Golf ball sitting on a tee

%hape of the articularsurfaces altered byvarying thic(ness oflabrum


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Glenoid Labrum

)ibrocartilaginousstructure

Attachment superior

glenoid rim loose goodmobility

Inferior attachment firmpoor mobility

*loc(s humeral head

translations

Increased area ofarticulation +mm sup$infmm ant$post


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Suction Cup - Matsen

G! -oint compressiveforce of the head of thehumerus into the soc(etexpels the synovial fluid tocreate a suction thatresists distraction"

.egative Interarticularpressure is produced bythe limited volume of fluid

Compressive loadproduced by dynamicaction of musclecontraction


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Shoulder Capsule

Large, looseredundant for large#/0

1ariable thic(ness oflayers with discretethic(ening 2 capsularligaments

Anterior glenohumeralligaments include:%uperior$ 0iddle$Inferior


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G-H Ligaments

Coracohumeral ligament isthe strongest supportingligament

Portions of theCoracohumeral ligamentform a tunnel for thebiceps tendon

Portion of the #otator CuffInterval

%uperior G! ligament andthe coracohumeral limitsexternal rotation andabduction of the humerus


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Anterior G-H Ligaments

%uperior glenohumeral

ligament forms the anterior

cover around the long

head of the biceps and partof #CI

0iddle glenohumeral

ligament blends with

portions of the

subscapularis tendon and

is taut at 34 abd, '54

extension and external

rotation Anterior stability

between 34 and 654


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Inferior glenohumeral

Hammock like

structure with

attachments to theanterior labrum

Most important

stabilizer against

anterior ineriordislocation


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otator Cuff I ter!al

#CI region of the shoulder plays a role in

the pathomechanics and intervention of

patients with shoulder instabilities"Anteriorsuperior aspect of the shoulder

7efects are associated with large sulcus

sign combined with anterior instability

!arryman +8, #owe 9', *% defects in

the #CI significant factor in instability


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otator Cuff Inter!al

*ordered by thesupraspinatus and

subscapularisCapsular tissuecovers it andreinforced by the

coracohumeral lig"; the deepestsegment of the%GL


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Isolated Closure of CI "efects

for Shoulder Instability)ield,


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ole of G-H Capsular

Ligaments Int & #$t rotation*ranch et al" Am %ports 0ed +

%ix Cadaveric shoulders

Increased flexibility of the anterior capsuleis most effected by external #ot

Increased flexibility of the posterior

capsule is most effected by internal #ot"*oth share in limiting rotation at a number

of positions


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Guanche et al% Am J Sports

Med% '%ynergistic action of the capsule andshoulder muscles

%timulation of the Anterior and inferioraxillary articular nerves $ 4licited 40Gactivity of the

*iceps, %ubscapularis,

%upraspinatus, and InfraspinatusPosterior axillary nerve > 40G activity ofthe 7eltoid


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"ynamic Stability of the G-H

(oint )ia * mechanisms'" oint compression 2 #C and

biceps increases the conforming fit

of the humeral head into glenoid $%uction cup

8" Coordinated contraction of the #C

muscles > )orce couple control thetranslations of the humeral head


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"ynamic Stability of G-H

&" %ynergistic action of capsular

mechanoreceptors and the #C

muscles Guanche3" Glenohumeral oint and

%capulothoracic must function in a

coordinated manner" %table baseallows glenoid to ad-ust to changing

arm positions"


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otator Cuff +athology

Classification:

A" Primary Compressive 7isease

*" %econdary Compressive 7isease

C" ?ensile in-ury

7" 0acrotrauma4" Anterior and Posterior Impingement


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, Secondary Compressi!e

"isease .nderlying Instability of

G-H Jt%

Budoff, Nirschl et al JBJS 1998 Debridement of

partial-thickness tears C !ithout acromioplast"#

%upraspinatus is small and relatively wea(susceptible to overuse and trauma

4ccentric overload wea(ens

musculotendinous rotator cuff unitEnable to oppose superior migration

causing secondary impingement"


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+athological Changes

7eltoid retainsstrength longer than#C loss of depressor

effect on humeral hd"7uring elevation

#eactive anddegenerative osseouschanges$ /steophytic

spurring causing awea(ened cuff torupture resulting fromimpingement


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/ype III acromion /endinosis


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Acromioplasty

%urgery results most predictable forpain relief$less for increased strength

7isrupts periosteum and corticalbone of acromion, predisposes toextensive scar

%ubacromial decompressionpartialthic(ness tears 2 relief from pain dueto Postop rest and denervation


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C,/ensile 1!erload

#epetitive intrinsictension overload" !eavyrepetitive eccentric forcesincurred by the posterior #C

during deceleration and followthru of overhead sport activitiescan lead to tendon failure"

Pathologic changesdegenerative process densefibroblasts and disorganiFedcollagen 2 absence of

inflammatory cells)orce '5+5. to the #Cduring arm decelerationphase of throwing


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",Macotraumatic /endon 0ailure

%ingle event that create

forces greater than the

tendon can tolerate

)ull thic(ness tears of the#C with bony avulsions of

the greater tuberosity

Classification:

Partial thic(ness %uperior

surface$*ursal impingeEndersurface tensile strength

less


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#, Internal Impingement

$mpin%ement of deep surface of the subscap tendon

and the reflection pulle" on the ant&sup %lenoid rim:'erber et al J Sh&(lbo! Sur% )***#

Increased internal rotation with '55 deg )lexionthe lesser tuberosity and biceps tendon are

brought closer to the ant$sup glenoid rim and the

superior G! lig becomes lax"

At +5 deg flexion and internal rotation the deepsurface of the subscap is impinging against the

glenoid rim


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+osterior G-H pain in o!erhead

thro2ing athletes

Superior Glenoid Impingement Jobe3

Clin 1rtho 454xternal rotation +5 deg"

Abduction and horiFontal

extension early part of the

acceleration phase of

overhead throwingBImpingement of inner fibers

of the #C ; post sup" labrum

between the grt" tub and

post"sup glenoid

%econdary to lac( ofresistance from the

subscapularis causing

angulation of the humeral

head instead of translation


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Scapula Asymmetry


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Loehr & .hthoff 675

cada!eris C

!0ost degenerative tears originated onarticular side supraspinatus near insertion

Poor blood supplyunable to repair itself Pain develops if the degeneration of tissue

becomes inflamed

.o evidence that full thic(ness tear heals

%mall tears usually get larger Pain not associated to tear siFe$ strength is

related to siFe of tear


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+oor lood Supply

Supraspinatus"pa#ue dye into micro blood $essels

%rm in &'( abd %rm in adduction


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otator Cuff +artial /hic8ness

/ear ursal SurfaceInternal rotation and

le)ion o the sh*


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+atient +rognostic 0actors

Poor outcomes associated with:

'" ?ear greater than ' cm

8" !istory of symptoms greater

than one year

&" %ignificant functional

impairment


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Surgical epair !s ehab

)altow et al Prospective patient

study surgery vs exercise

69D of the surgical patients

66D of the exercise patients were

successful )$E 6 mo" 2 8"6 years

8D of the exercise group and 5D of

the placebo group had surgery


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1pen C epair !s Arthroscopic

"ebridement and "ecompression*ur(art /rthop Clin .orth Am '++&

8 patients 7ebridement and

7ecompression&5 mo )$E 2 95D pts" Good or excellentresults

0ontgomery %h 4lbow %urg '++3

9 patients )ull thic(ness #C tears8 year )$E open repair superior resultsas compared to arthroscopic group


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Impingement Syndrome

/reatment approachBan% + De"le ' Comparsion of super.ised

e/ercise !ith !ithout manual 0 for patients !ith

shoulder impin%ement s"ndrome J2S0 )***

.>8 8x$w( for & wee(s

*oth groups had the same exercise regime

0anual therapy group 0aitlandB %uperior to

exercise group only

0anual therapy group had significant increase in

strength, #/0, and decreased pain


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Scapular 9i ematics,

Stre gthe i g & Stretchi g


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/reatment Approach to

C /ears#educe pain andrestore scapulamobility andstrength

#estoration of G! -oint #/?A?I/.,arthro(inematics

Increase strengthand balance oflocal muscles


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Scapula Mobili:ation


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Scapula otator - #$ercises

7ec(er et al A%0 '+++

7ynamic !ug greatest

40G activity of

%erratus anterior

Lear ; Gross /%P? +9

Increase 40G for

serratus and upper

traps with pushup

with a plus and

elevation of the feet


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Scapula Strengthening

"ynamic Hug


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Case +resentation

Impingement %yndrome

!istory of thyroid resection

secondary to cancer of the thyroidEnable to palpatesternocleidomastoid, Anterior

scalene)orward head posture 2 Poorscapula rotator strength


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efore After


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efore After


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Scapula otator ;ea8ness


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#$ercises


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Case st d 0ootball +la er


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Case study 0ootball +layer

Impingement "iagnosis

efore After


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Strength /raining


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Summary

Anatomical factors stability and instabilityeg" Central position of humerus on glenoid

7ynamic stability importance of the rotatorcuff and scapula rotators

#otator Cuff 7isease is results frominstability, impingement, #C tear

0uscle activity can cause instability andcompressive force to the -oint" Improperexercise may cause shoulder dysfunction

anatomy of instability

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