9/30 - Shoulder Instability Non-Op

Question 1

what direction is the GH joint deeper in

Answer 1

superior-inferior

Question 2

describe the GH joint’s set up

Answer 2

least constrained joint in body

glenoid surface 1/4 surface area of humeral head
- 1/3 of humeral head in contact w fossa at any given time

bony congruence limited

Question 3

what is the significance of limited bony congruence in the GH joint

Answer 3

relying on other structures to stay centered

Question 4

describe how the quality of the glenoid articular cartilage changes

Answer 4

thicker peripherally

Question 5

GH laxity

Answer 5

ability to translate humeral head on glenoid fossa

Question 6

GH instability

Answer 6

unwanted and excessive translation of humeral head on glenoid fossa causing alteration in comfort and/or function

Question 7

subluxation

Answer 7

complete separation of articular surfaces w spontaneous reduction

Question 8

dislocation

Answer 8

complete separation of articular surfaces without spontaneous reduction
- remains dislocated until maneuver or force

Question 9

how is time crucial when it comes to relocation of a dislocation

Answer 9

longer it takes, higher the risk of neurovascular injury
- tension and load on brachial plexus and vascular
- longer it’s there, harder to come back (esp for nerves)

this factors into our goals
important to ask if dislocation how long it was out of place for

Question 10

where do you see the biggest difference in ROM in normal laxity vs normal shoulder w no laxity

Answer 10

inferior slightly more in normal laxity
- anterior and posterior will be pretty much the same as a normal shoulder

Question 11

what structures provide stability for the shoulder (7)

Answer 11

labrum
ligaments & capsule
biceps
rotator cuff
scapula
neuromuscular control
negative intra-articular pressure

Question 12

if someone had a shoulder dislocation, what should you assess next

Answer 12

if any of the stability structures were damaged
- labrum
- ligaments & capsule
- biceps
- rotator cuff
- scapula
- neuromuscular control
- negative intra-articular pressure

Question 13

what is the labrum

Answer 13

fibrocartilage surrounding glenoid rim

Question 14

what functions does the labrum provide (3)

Answer 14

1. attachment site for glenohumeral capsule and ligaments
2. chock-block effect that limits translation
3. inc depth of glenoid fossa by 50%

Question 15

what happens if the labrum is damaged

Answer 15

back to a shallow glenoid fossa w poor bony congruence and stability

Question 16

what is the function of ligamentous structures and capsule

Answer 16

provide stability at end ranges of motion

Question 17

what ligamentous structures are involved in the shoulder

Answer 17

coracohumeral ligament
superior GH ligament
middle GH ligament
inferior GH ligament
- anterior and posterior bands

Question 18

what ligament of the shoulder has a hammock effect? what does this mean?

Answer 18

inferior GH ligament
- anterior and posterior band

as bring arm up to ABD 90 there is tension in inferior; anterior and posterior will come up to hug front and back

Question 19

how are the ligaments of the shoulders structured

Answer 19

thickenings of capsule

Question 20

what is the circle of stability concept

Answer 20

what happens if one is damaged depends on integrity of other structures there

ex: cut anterior capsule
whether it dislocates anterior:
- dependent on posterior capsule integrity
- inc translation or subluxation

Question 21

what provides primary restraint in early ROM

Answer 21

negative intra-articular pressure

Question 22

what provides primary restraint in mid-range

Answer 22

muscle function

Question 23

what provides primary restraint in end range

Answer 23

capsule
- no tension on passive structures prior to this range

Question 24

what is the structure of the long head of biceps

Answer 24

blends w superior glenoid labrum

Question 25

origin of long head of biceps function (3)

Answer 25

stabilizes arm in ABD and ER generates joint compressive forces dec anterior, superior, and inferior translation of humeral head when taut

Question 26

if seeing an overuse injury in biceps but not an event to cause overuse, what should you think and why

Answer 26

might be bc of hypermobility - if underlying shoulder hypermobility, will work harder to create stability via compressive forces >> leading to some biceps irritation

Question 27

what is the primary role of the rotator cuff

Answer 27

provides dynamic stabilization by compressing humeral head into glenoid

Question 28

where do RC ms insert into and why is this important

Answer 28

blend w capsule & creates dynamic ligament tension if laxity in ligamentous structures, the RC ms working can create stability via dynamic ligament tension

Question 29

what is the function of scapula upward rotation

Answer 29

provides stable environment of joint contact

Question 30

what other motions do you see at the scapula during upward rotation/elevation

Answer 30

ABD and tilts posteriorly

Question 31

what is required for distal mobility

Answer 31

proximal stability

Question 32

what is proximal stability needed for

Answer 32

distal mobility

Question 33

what are the advantages to exercises done in the scapula plane (4)

Answer 33

inc stability w joint congruence - good bony stability - good stability of capsular ligamentous minimal capsular tightness functional plane of motion ideal position for RC strengthening

Question 34

what is the scapula plane referring to

Answer 34

position of the glenoid

Question 35

what are components contributing to neuromuscular control

Answer 35

efferent/motor responses to afferent/sensory info

Question 36

proprioception

Answer 36

awareness of joint position

Question 37

kinesthesia

Answer 37

awareness of joint motion

Question 38

why are we concerned if a person w an unstable shoulder has poor proprioceptive and kinesthetic sensation

Answer 38

when brain doesn't know where joint is in space, inc risk for injury - won't tell you when in an end range injury provoking situation and won't enact protective measures (ie late cocking phase)

Question 39

what is negative intra-articular pressure

Answer 39

creates sealed compartment vacuum effect b/w articular surfaces - compresses head of humerus

Question 40

why is negative intra-articular pressure lost w surgery and why is this important

Answer 40

surgery cutting thru capsule, will be venting it - inc mobility, 40-60% inc in translation

Question 41

why are AMBRI joints best served by a PT intervention instead of surgery

Answer 41

if tighten structures in surgery, likely stretch back out over time

Question 42

what are considerations for instability (8)

Answer 42

severity direction etiology frequency (# of episodes) +/- underlying soft tissue laxity or connective tissue disorder concomitant path end-range NM control premorbid activity level

Question 43

what about the severity of the instability should be considered

Answer 43

subluxation - physiologic integrity exceeded dislocation - physiologic & anatomic integrity exceeded

Question 44

direction of instability possibilities?

Answer 44

unidirectional multidirectional (MDI)

Question 45

etiologies for instability

Answer 45

traumatic atraumatic

Question 46

frequencies for instability

Answer 46

primary recurrent

Question 47

why does it take less for a subsequent dislocation or subluxation

Answer 47

load on passive structures will stretch out won't take as much load for same things to happen

Question 48

what are concomitant pathologies for instability

Answer 48

SLAP lesion bankart lesion

Question 49

SLAP vs Bankart

Answer 49

SLAP - superior labrum anterior posterior Bankart - anterior inferior damage

Question 50

what is a commonly associated w a hill-sachs lesion? why?

Answer 50

associated glenoid bone loss HOH rolls over rim of glenoid when dislocates - compressive forces that damage the glenoid (bone and cartilage loss)

Question 51

why is there value to imaging if a dislocated shoulder has already been relocated

Answer 51

see integrity of the bone - if there is bone loss, can continue to waste away

Question 52

what is a SLAP lesion

Answer 52

disruption of superior labral-biceps complex involving tearing, separation or both of the superior labrum beginning posterior to biceps tendon insertion and then extending anteriorly

Question 53

what is the peel back mechanism

Answer 53

ABD & ER in late cocking phase of throwing twisting at base of biceps transmits torsional force to anchor

Question 54

what is a concern w traumatic anterior instability

Answer 54

brachial plexus injuries (esp axillary n.) - humerus comes out the front - that is where the NM structures are

Question 55

what is a negative to the use of slings

Answer 55

minimize strength and motor control from disuse - more for comfort usually