The Shoulder Flashcards
The glenohumeral joint rotates around how many axes?
three (triaxial joint)
What is the orientation of the glenoid fossa?
laterally from the scapula (7°), posteriorly, slight (5°) superior tilt relative to the medial border of the scapula
What about the orientation of the glenoid fossa is thought to assist with joint stability?
slight superior tilt provides greater resistance to inferior forces (may assist with joint instability)
What type of connective tissue is the glenoid labrum?
fibrocartilage
What is the glenoid labrum and what role does it play in the function of the shoulder?
fibrocartilage tissue that surrounds the glenoid;
- deeps the fossa, supplies a negative intraarticular vacuum effect (seals the joint & assists with stability)
How do injury of the glenohumeral capsule or labrum lead to glenohumeral instability?
disruption of the seal of the glenohumeral joint / intraarticular vacuum effect
Describe the attachments of the glenohumeral joint capsule
arises from the glenoid neck & labrum, inserts into the articular margin of the anatomical neck of the humeral head
(Except inferio-medially, where it extends a slight ways down the humeral neck)
Where are there openings in the glenohumeral joint capsule?
- between the humeral tubercles (biceps tendon exits)
- connection between the superior and middle glenohumeral ligaments (subscapularis bursa communicates with joint cavity)
Which bursa communicates with the glenohumeral joint cavity?
subscapular(is) bursa
Where are the glenohumeral ligaments located in relation to the joint capsule?
extracapsular ligaments surround superior and anterior joint, while posterior is thin
What motion(s) does the superior glenohumeral ligament resist?
inferior translation of humeral head when arm is in adduction at side
What connective tissue structure rests over the head of the humerus & directly beneath the rotator cuff?
superior glenohumeral ligament
What is the relationship between injury of the superior glenohumeral capsule and translation of the humeral head?
- tear in the capsule at the greater tuberosity (may be seen with partial RTC tear) increases anterior & inferior translation
- defect seen in massive RTC tear increases translations in all directions
What motion does the middle glenohumeral ligament resist?
anterior humeral translation with arm in mid-range abduction, limits external rotation with arm at side
Describe the structure of the inferior glenohumeral ligament complex.
- expansive band of tissue in inferior capsule
- thick in anterior and posterior bands
- “hammock” type axillary pouch
What motions does the inferior glenohumeral ligament resist?
Anterior and posterior translation of the humeral head after 90° of abduction:
- during external rotation and abduction, the anterior band wraps around the front and limits anterior translation
- during internal rotation, the posterior band wraps around and limits posterior translation
Name the 3 borders of the scapula
superior border, axillary border, vertebral border
Name the 3 angles of the scapula.
superior medial angle, inferior medial angle, lateral (glenoid) angle
At which spinal level is the superior margin of the scapula?
T2 spinous process
At which spinal level is the medial spine of the scapula?
T3 spinous process
At which spinal level is the inferior medial angle of the scapula?
T7 spinous process
What is the plane of the scapula?
30° to 45° from the coronal plane
What are the two roles of the acromion?
- serves as a lever arm for the deltoid
- articulates with the lateral end clavicle (AC joint)
What is the shape of the sternoclavicular joint? What motions does this shape allow?
saddle-shaped: protraction/retraction, elevation/depression, & some rotation around its long axis
Describe the capsuloligamentous structures of the sternoclavicular joint.
relatively weak capsule supported by thickenings (anterior and posterior sternoclavicular ligaments)
What is the most important ligament in the sternoclavicular joint & why?
posterior sternoclavicular ligament; sectioning of this structure causes significant increases in anterior and posterior translations
What is the interclavicular ligament & what motions does it resist?
connects both clavicles medially; resists inferior forces on the medial clavicle
What are the attachments of the costoclavicular ligament complex?
runs from superior surface of 1st rib to undersurface of the medial clavicle
Which ligament runs from the 1st rib to the medial clavicle?
costoclavicular ligament
What motion does the costoclavicular ligament resist?
resists superior force on medial clavicle when the lateral clavicle / shoulder is depressed (posterior & anterior bodies)
How many degrees of freedom does the acromioclavicular joint have? What are they?
three: protraction/retraction, elevation/depression, & rotation
What ligaments stabilize the acromioclavicular joint?
Conoid ligament (behind) & Trapezoid ligament (in front); Collectively, they are referred to as coracoclavicular ligaments
How does the acromioclavicular joint tissue change throughout life?
hyaline articular cartilage becomes fibrocartilage on the acromial side (age 17) & then on the clavicular side (age 24)
What is the role of the acromioclavicular joint meniscus?
increase stability by improving the fit between the two surfaces
What are the attachments of the conoid ligament?
runs vertically from the coracoid process to the clavicle
What motions does the conoid ligament resist?
resists elevation and protraction of the clavicle
What motions does the trapezoid ligament resist?
resists acromioclavicular joint distraction (provides joint compression), and secondarily resists clavicle elevation and protraction
These ligaments resist elevation of the distal clavicle.
Coracoacromial ligaments (conoid and trapezoid)
Due to its ligamentous attachments, what other motion does the clavicle undergo when it is elevated?
Posterior rotation of the clavicle
Describe the concept of scapulohumeral rhythm (“2 to 1”)
shoulder elevation is created by both movement of the scapula (60° rotation) and of the glenohumeral joint (120° elevation);
The rhythm of “2 to 1” refers to the fact that approximately 2° of motion occurs at the glenohumeral joint for every 1° of the scapula.
Describe the concept of a force couple.
two or more muscles or groups of muscle on opposite sides of a joint work together to provide stability or movement of a joint segment
Describe the Deltoid / Rotator Cuff force coupling that occurs in the shoulder.
The vertical force by the deltoid is offset by the horizontal (inferior and medial) forces of the rotator cuff as they act in opposite directions on either side of the center of rotation of the humeral head (infraspinatus, subscapularis, and teres minor provide inferior/medial force, while supraspinatus compresses the humeral head in the glenoid)
Without the rotator cuff, what would happen during attempted arm elevation?
the deltoid would pull the humeral head superiorly and the greater tuberosity would hit the underside of the acromion / coracoacromial arch
How does pressure from the humeral head onto the coracoacromial arch change when the rotator cuff is not working properly?
force increases 60%
At what general ranges of motion is glenohumeral cavity-compression the greatest?
compression of the humeral head into the glenoid fossa is more common at mid-ranges (where capsular structures are lax), it may also occur at end-ranges where humeral joint forces are increased
Give three examples of force couples that occur in the shoulder.
- Deltoid / Rotator Cuff
- Upper Trapezius / Serratus Anterior
- Anterior-Posterior Rotator Cuff Muscles
What are the four functions of the Trapezius / Serratus Anterior force coupling that occurs in the shoulder.
- allows for upward (lateral) rotation of the scapula, maintaining the glenoid for optimal positioning
- maintains an efficient length-tension relationship for the deltoid
- decreases “impingement”
force on subacromial structures - provides stable scapular base, “enabling appropriate recruitment of scapulohumeral muscles”
What movement is produced with the Upper Trapezius / Serratus Anterior force coupling in the shoulder?
Upward (lateral) scapular rotation
Describe the Upper Trapezius / Serratus Anterior force coupling that occurs through varying degrees of shoulder abduction.
Lower portion of Serratus Anterior & Lower Trap. contract in conjunction with Upper Trap. & Levator Scapula. The result is rotation of the scapula around a moving axis.
Early in abduction, the axis is near the medial border of the scapular spine (this gives a the Lower Trap. a very small lever arm, since it attaches near this spot).
As abduction continues, the axis moves laterally along the scapular spine toward the ACJ, creating an increasingly longer lever arm for the Lower Trap.
At 90° or more of shoulder elevation, Serratus Anterior and Lower Trap. are primary components of scapular rotation and stabilization.
What muscular abnormalities have been recorded in patients with Impingement Syndrome of the shoulder?
decreased levels of Serratus Anterior activity, delayed firing of Middle and Lower Trap., and increased activity of Upper Trap. and Levator Scapula
Describe the Anterior-Posterior Rotator Cuff force coupling in the shoulder
Subscapularis (anteriorly) and Infraspinatus & Teres Minor (posteriorly) create both inferior and compressive stability;
Describe the concept of the rotator cuff muscles as a “suspension bridge” that influences humeral head movement.
Subscapularis, Infraspinatus, and Teres Minor create inferior and compressive stability / create a stable fulcrum to allow for concentric rotation of the humeral head on the glenoid
In what ranges of shoulder elevation are the Subscapularis, Infraspinatus, and Teres Minor most active?
Mid ranges
What imbalances are frequently found in the Anterior-Posterior Rotator Cuff force couple?
selective development of the internal rotators and subscapularis in athletes / active individuals without development of the posterior rotator cuff
What is the effect of an isolated supraspinatus tear on the “suspension bridge” phenomenon of the shoulder?
the anterior-posterior force couple remains intact
What are the 7 components of the clinical examination of the shoulder?
- Observation and posture
- Scapular evaluation
- Glenohumeral joint range of motion
- Manual muscle testing (supraspinatus, infraspinatus, teres minor, subscapularis)
- Related referral joint testing (cervical, elbow)
- Special tests (impingement, instability, labrum)
- Functional testing
What are the theoretical explanations for shoulder height asymmetry?
dominant shoulder is typically lower: increased mass in the dominant arm; elongation of periscapular musculature secondary to eccentric loading
What is the purpose of performing visual observation of the patient in standing during an examination of the shoulder?
In quiet standing and hands-on-hips standing, you can observe for muscle symmetry and focal atrophy
When performing the posture/observation portion of a shoulder examination, why have the patient perform hands-on-hips standing as opposed to neutral arm position?
it places the shoulder in 45°-50° of abduction and slight internal rotation; It allows the patient to relax the arms and allows a better chance of spotting atrophy of the muscles along the scapular border and infraspinous fossa
What might cause observable atrophy of the infraspinatus?
- rotator cuff dysfunction
- suprascapular nerve involvement (severe atrophy)
Where does impingement of the suprascapular nerve commonly occur?
suprascapular notch (a.k.a. the spinoglenoid notch)
What are paralabral cysts and how to they impact nearby tissue?
swellings / collections of fluid that occur within 1 cm of the labrum; they can compress and impinge on the suprascapular nerve as it travels around the spinoglenoid notch on its way to the infraspinatus
Injury to what area of the shoulder joint labrum is most often associated with paralabral cyst formation?
superior
Explain how a shoulder joint labral lesion can directly lead to atrophy of the infraspinatus.
Superior labral lesions can cause the formation of a paralabral cyst, which can impinge on the supraspinous nerve and disrupt the innervation of the infraspinatus.
What is the appropriate course of action if extreme wasting of the infraspinatus muscle is observed?
recommend further diagnostic testing to rule out suprascapular nerve involvement
Describe the Kibler Scapular Slide test.
Measure the distance between the closest thoracic spinous process and the inferior angle of the scapula in 3 positions:
- arms by sides
- hands on hips
- arms at 90° abduction + internal rotation
a difference between sides of 1.5cm (one finger-width) or greater may indicate scapular muscle weakness or poor overall stabilization of the scapulothoracic joint
What are the 3 dysfunctions of the scapula described by Kibler et al?
- inferior angle
- medial border
- superior
Describe inferior angle scapular dysfunction, as per Kibler et al. What other condition is this commonly seen with?
- anterior tipping of scapula in frontal plane (inferior border is prominent)
- commonly seen with subacromial pain syndrome (anterior tipping causes the acromion to press down on an elevated humerus?)
Describe medial border scapular dysfunction, as per Kibler et al. What other condition is this commonly seen with?
internal rotation of the scapula tilts the glenoid forward (“antetilting”), which allows for and opening up of the front half of the glenohumeral joint articulation.
- commonly seen with glenohumeral joint instability & thought to be a component of subluxation/dislocation
Describe superior scapular dysfunction, as per Kibler et al. What other condition is this commonly seen with?
- early & excessive superior scapular elevation during arm elevation
- typically results from rotator cuff weakness & force couple imbalances
What does a kappa score measure in research? Why is it useful? How is it measured?
- measures inter-rater or intra-rater reliability
- it’s better than a simple percentage of agreement between two raters, because it that takes into account the possibility of an agreement occurring by chance
- measured on a scale from 0.01 - 1.00.
- 0.01-0.2 = none/slight
- 0.21-.4 = fair
- 0.41-0.6 = moderate
- 0.61-0.8 = substantial
- 0.81-1.0 = almost perfect agreement
What statistical support does classification of scapular dysfunction have?
- evaluations of 26 - 56 individuals
- Interrater reliabilities range from k = 0.40 to 0.61 (moderate score)
List 4 tests that might be used during an evaluation of the scapula.
- Scapular Slide test
- Scapular Assistance test
- Scapular Retraction test
- Flip Sign
Describe the Scapular Assistance test.
Examiner’s hands on inferior medial aspect & superior base of scapula; examiner assists with rotation during active elevation in either scaption or flexion;
(+) if ROM is increased or pain is decreased
Describe the Scapular Retraction test.
Examiner manually retracts the scapula while the patient performs the painful movement (usually IR or ER at 90° abduction - common in overhead athletes with posterior impingement and RTC pathology);
(+) if ROM is increased or pain is decreased
Describe the Flip Sign.
Examiner resists ER with shoulder in slight abduction;
(+) if medial border of scapula “flips” away from the thorax;
indicates a loss of scapular stability
If a patient with shoulder pain presents with a (+) Flip Sign, what exercises are likely to help.
(+) Flip Sign is indicative of a loss of stability of the scapula; Exercises to strengthen/increase the serratus anterior / trapezius force couple will help to increase scapular stability
Why is the loss of glenohumeral internal rotation clinically important? What populations consistently present with this issue?
- loss of IR can indicate posterior capsule tightness
- can cause increased anterior humeral head translation
- increased anterior humeral shear (happens during the follow-through of a throw or swing/serve)
- increased superior migration of humeral head during shoulder elevation
- cadaver studies show that humeral head shifts antero-/superiorly with arm in 90° abd / 90° ER position
- increased subacromial contact area & contact forces on RTC
- common in overhead athletes (esp. tennis players and baseball pitchers)
List 3 manual muscle test positions are used to evaluate the supraspinatus? Which is most highly recommended by the monograph’s authors & why?
- Full can test
- Empty can test
- Champagne Toast test;
authors recommend Champagne Toast test, because it seems to have the best ratio of supraspinatus to deltoid activation
What is the optimal position to test the strength of the infraspinatus muscle, according to Kelly et al?
- Patient seated
- 0° shoulder flexion
- 45° internal rotation
Describe the purpose and performance of the Patte test.
- isolate the teres minor muscle to assess strength / tolerance for loading
- 90° shoulder scaption
- 90° external rotation
- pt resists external rotation
According to Kelly et al, what is the optimal position for testing the strength of the subscapularis muscle?
Gerber lift-off position
(back of hand lifting away from inferior border of ipsilateral scapula)
Using handheld dynamometers, what did Reimann et al conclude about rotator cuff strength differences between dominant and non-dominant shoulders?
The dominant limb was found to have significantly stronger internal rotation. External rotation was equal.
Describe the interpretation of the Spurling’s Compressive Test in an examination of a patient with shoulder pain.
Spurling’s test is not sensitive (30%), but it is specific (93%) for cervical radiculopathy. Just because it doesn’t recreate shoulder pain doesn’t mean there isn’t any cervical involvement/referral.
What are two reasons that you might screen the elbow when you suspect shoulder pathology?
- Shoulder injury can refer symptoms to the elbow
- Elbow injuries can occur alongside shoulder injuries (in throwing athletes & during sling use following surgery)
During a shoulder examination, what two elbow tests are recommended by the monograph authors?
- Valgus Stress Test
- Laterally-based Extensor Provocation Test
Describe the Valgus Stress test of the elbow. What is this testing?
- elbow placed in 15-25° of flexion (puts capsule on slack and “unlocks” the olecranon from the olecranon fossa)
- apply medial force to stress the Ulnar Collateral Ligament
Describe the Laterally-based Extensor Provocation Test. What is this testing?
- elbow is fully extended
- resist wrist extension
- loads the lateral epicondylar region
What are the three categories of special tests for the shoulder described by the monograph authors?
- Impingement tests
- Instability tests
- Labral tests
Describe the 5 shoulder impingement tests listed in the monograph. Which of these are the best supported?
- Neer Impingement test
- Hawkins-Kennedy Impingement test
- Coracoid Impingement test
- Cross-arm Adduction test
- Yocum test
- Neer test is 53% sp, 79% sn; Hawkins-Kennedy is 59% sp, 79% sn
Compare/contrast the Hawkins-Kennedy Impingement with the Coracoid Impingement test.
both include forced shoulder internal rotation, but the Hawkins-Kennedy test is 90° of scaption. The Coracoid Impingement test is performed in 90° of flexion.
What are the two main types of shoulder instability tests?
- Humeral head translation tests
- Provocation tests
What is the approximate ratio of normal anterior-to-posterior humeral head translation in the glenoid?
1:1 (7.8-7.9 mm)
What is the average normal inferior displacement of the humeral head in the glenoid?
1 cm
Describe the MDI Sulcus test
a.k.a. Multi-directional Instability Sulcus Test
- patient seated
- shoulder in neutral
- hands resting on lap
- several brief, relatively rapid downward pulls on the humerus
- (+) “sulcus sign” if there is tethering of the skin between the lateral acromion and the humerus (widening of subacromial space)
The MDI Sulcus test assesses the integrity of which two structures of the shoulder?
superior GH ligament & coracohumeral ligament
Which shoulder special test is used to assess the integrity of the superior glenohumeral ligament and/or the coracohumeral ligament?
Multi-directional Instability Sulcus test
Why should a patient be positioned in supine in order to test for anterior/posterior shoulder joint laxity?
allows the patient’s shoulder to be tested in multiple degrees of abduction (selectively stresses different portions of the capsule and capsular ligaments)
List the 5 shoulder instability tests described in the monograph.
- MDI Sulcus test
- Supine Anterior Humeral Head Translation test
- Supine Posterior Humeral Head Translation test
- Subluxation Relocation test
- General hypermobility testing (e.g. the Beighton hypermobility scale/index)
Describe the Anterior and Posterior Humeral Head Translation tests.
- designed to assess laxity of the anterior/posterior capsule and/or capsular ligaments
- patient is supine, shoulder in scapular plane
- because the glenoid is angled at 30°, translation should be antero-medial / postero-lateral
- anterior translation performed at 3 ranges of abduction (0-30°, 30-60°, 90°)
- posterior translation only performed at 90°
During the Anterior Humeral Head Translation test, in what range of degrees of abduction would you place the shoulder in order to test the integrity of the superior glenohumeral ligament?
0-30° abduction
During the Anterior Humeral Head Translation test, in what range of degrees of abduction would you place the shoulder in order to test the integrity of the middle glenohumeral ligament?
30-60° abduction
During the Anterior Humeral Head Translation test, in how many degrees of abduction would you place the shoulder in order to test the integrity of the inferior glenohumeral ligament?
90°
Why is the Posterior Humeral Head Translation test performed in 90° of abduction?
there’s no distinct thickenings of the capsule in the posterior portion aside from the posterior band of the inferior glenohumeral ligament complex, which is stressed most in 90° of abduction
Describe the grading system for Humeral Head Translation testing.
Grade I: translation of humeral head without “edge loading” or translation of the humeral head over the glenoid rim
Grade II: translation up and over the glenoid rim with spontaneous return
Grade III: no return/relocation (rare in PT clinic)
How reliable is the grading system Humeral Head Translation testing?
- Of the 3 grades, interrater reliability is best in distinguishing between grades I and II (does the head of the humerus traverse the glenoid rim?)
- adding on other estimators like end-feel decreases interrater reliability
Describe the Subluxation Relocation test. Why is this test a useful supplement to the MDI Sulcus test and Anterior/Posterior Translation testing?
- pt supine
- 90° shoulder abduction
- max ER
- PT provides mild anterior subluxation force
- if anterior/posterior sx are reproduced, PT applies a gentle postero-lateral force to the anterior shoulder
- failure to reproduce symptoms leads PT to reattempt at 110° and 120° abduction
- (+) test is when symptoms are reproduced with anterior translation & diminished with poster-lateral translation
What is “occult” shoulder instability? What is a clinical indicator of this type of instability, according to the monograph authors?
- Shoulder pain (common to overhead athletes) due to subtle lack of ligamentous restraint that is currently difficult to measure
- apprehension with anterior translation of the humeral head during the Subluxation Relocation test is (+) indicator
Contrast the reproduction of anterior vs posterior shoulder pain during the Subluxation Relocation test.
- anterior pain: anterior instability / secondary glenohumeral joint impingement
- posterior pain: posterior or internal impingement
Aside from shoulder joint instability, what other condition may be implicated in patients with a positive Subluxation Relocation test?
Type II superior labrum anterior to posterior (SLAP) lesion
What scale is used in assessing general hypermobility?
the Beighton hypermobility scale/index
Describe the 9 items in the Beighton hypermobility scale/index.
(Bilateral)
1 & 2: 5th MCP hyperextension
3 & 4: Passive thumb to forearm
5 & 6: Elbow hyperextension
7 & 8: Knee hyperextension
9: Standing trunk flexion with knees fully extended
How many items does the Beighton hypermobility scale/index consist of?
9
How many items of the Beighton scale must be positive in order to grade the patient as “hypermobile”?
No consensus. Some studies say 2 out of 9, some say 4 out of 9. The testing is better for an overall understanding of the patient’s tendency toward ligamentous laxity & guide progression rates for ROM or mobilization.
List the 8 shoulder labral tests described in the monograph.
General tests:
1. Clunk test
2. Circumduction test
3. Compression Rotation test
4. Crank test
Location-specific tests:
5. O’Brien Active Compression test
6. Mimori test
7. Biceps Load test
8. ER Supination test
What are the 2 categories of shoulder labral tests described in the monograph? What is the difference between the two?
- General: uses long axis compression to scour the glenoid with the humeral head (traps torn/detached labral segment)
- Location-specific: use muscular tension via the long head of the bicep on the superior labrum (specifically used for identifying superior labral lesions)
What are the two main functions of the glenoid labrum?
- deepens the glenoid fossa, enhancing the concavity
- serves as an attachment site for the glenohumeral ligaments (secures the humeral head in the glenoid)
What is the effect of injury to the labrum on glenohumeral joint compression?
labral injury has been shown to decrease concavity compression up to 50%
Describe the effect of anterior translation forces on the humeral head in overhead throwing athletes.
Anterior translation forces can be up to 50% of body weight during arm acceleration of the throwing motion (arm in 90° abduction & ER)
How does increased capsular laxity / generalized joint hypermobility affect forces on the glenoid labrum in both the short- and long-term?
increased humeral head translation, which can subject the labrum to increased shear forces
- repeated translation of the head against the labrum can lead to tearing or detachment from the glenoid
List the 5 types of glenoid labrum tears described in the monograph.
- transverse
- longitudinal
- flap
- horizontal cleavage
- fibrillated
In what parts of the labrum do tears most commonly occur?
- anterior-superior (60%)
- posterior-superior (18%)
- only 1% in anterior-inferior labrum
- multiple areas (22%)
What are the general outcomes of arthroscopic labral debridement procedures in patients with shoulder joint hypermobility? What are the clinical implications of these outcomes?
- 72% of people report acute relief of symptoms during the first year, but only 7% reported relief at 2 years
- debridement is not an effective long-term solution for labral tears
- underlying instability in overhead athletes needs to be address to improve pain and return to function in the long run
What is the difference between a SLAP or Bankart lesion vs. a labral tear?
SLAP / Bankart lesions are labral detachments of the labrum from the rim
What are the two most common labral detachments?
SLAP lesion & Bankart lesion
What is a Bankart lesion? What is its relationship to dislocation?
labral detachment that occurs between 2 o’clock and 6 o’clock (on a right shoulder)
- up to 85% of people with dislocation have a Bankart lesion
What is a SLAP lesion? Why is the loss of shoulder stability so significant with these lesions?
- labral detachment that occurs in the superior aspect of the labrum
- involves the tendon of the long head of the biceps, which is no longer anchored to the glenoid (loss of static stability)
What was the effect of a surgically-induced SLAP lesion on glenohumeral joint stability?
- experimenters created a SLAP lesion between the 10 o’clock and 2 o’clock positions
- 11-19% decrease in ability of the GH joint to withstand rotational force
- 100%-120% increase in strain on anterior band of the inferior GH ligament
What is the “peel back mechanism” that is hypothesized to cause glenoid labral injury?
the torsional force created with the abducted arm is brought into maximal ER “peels back” the biceps and labrum
What activity puts the most strain through the biceps tendon in overhead athletes? What other forces on the shoulder are relevant in this situation?
decelerates the extending elbow during the follow-through phase of pitching
- coupled with the large (“violent”) distraction forces produced during follow-though, this is a hypothesized mechanism of SLAP lesions
What can cadaver studies tell us about mechanisms of superior labral injuries?
- experimenters looked at load vs failure in cadavers
- compared distraction vs “peel back” simulation models
- significantly lower load to failure for peel back model (90° abduction, max ER)
Which 4 special tests of the shoulder attempt to mimic the “peel back” mechanism?
- O’Brien Active Compression test
- Mimori test
- Biceps Load test
- ER Supination test
Discuss the diagnostic accuracy of clinical tests to identify glenoid labrum pathology.
The sensitivity and specificity of these tests varies among studies (Sn 76-92%, Sp 42-91%), so they should be used in clusters and confirmed by MRI with contrast.
What pathologies might be detected via shoulder radiographs?
fracture, calcification (esp. in supraspinatus), rotator cuff tears
How might a shoulder radiograph show signs of a rotator cuff tear?
- irregularity of greater tuberosity
- sclerosis of underside of acromion
- elevated humeral head (deltoid unopposed by RTC)
How does calcification of the supraspinatus typically occur?
bloody hemorrhage coagulates and calcifies
What shoulder pathologies might be detected via computed tomography?
-subtle or complex fractures of humerus or glenoid
- arthritic changes
- loose bodies
- Hill-Sachs lesions
What intra- and extra-articular structures of the shoulder can be assessed using MRI?
- Intra-articular: ligaments, capsules, synovium, labrum
- Extra-articular: ligaments, bursae, tendons
What is the effect of adding contrast to a shoulder MRI?
- increases the ability to determine RTC tears and labral tears
- gadolinium distends the joint and separates intraarticular structures, extending into defects/tears in the tissue
What 2 functional tests for the shoulder are recommended by the monograph authors?
- Closed Kinetic Chain Upper Extremity Stability test
- Functional Throwing Performance Index
Describe the Closed Kinetic Chain Upper Extremity Stability test.
- 2 pieces of tape 3 feet apart on floor
- patient assumes push-up position with hands just inside the tape
- patient alternates touching opposite tape for 15 seconds
What does the Closed Kinetic Chain Upper Extremity Stability test assess? Why is this better than simply performing a push-up?
- the ability of the shoulder to function in a closed kinetic chain environment
- better than a push-up, because it doesn’t stress the anterior shoulder (happens during push-up descent)
Describe the Functional Throwing Performance Index.
- series of repetitive throws at a target
- scores both accuracy and ability to functionally perform the throwing motion
Why might isokinetic testing of shoulder musculature be more beneficial than manual muscle testing?
accommodating resistance & ability to test glenohumeral joint at faster, more functional angular velocities
What are the limitations of manual muscle testing of the shoulder joint?
- when there is a minor strength impairment or isolated strength deficit
- difficult to assess antagonist/agonist muscular strength imbalances
What are the 5 key pathophysiologic factors that lead to rotator cuff disease?
- Primary impingement
- Secondary impingement
- Tensile overload
- Microtraumatic tendon failure
- Posterior / undersurface impingement
What is primary rotator cuff compressive disease also known as?
primary impingement
What is primary rotator cuff impingement?
compression of rotator cuff tendons between the humeral head and the anterior 1/3 of the acromion, coracoacromial ligament, coracoid, or acromioclavicular joint
During primary rotator cuff impingement, the rotator cuff tendons can be compressed between the humeral head and what 4 structures?
- anterior 1/3 of the acromion
- coracoacromial ligament
- coracoid
- acromioclavicular joint
What did Poppen & Walker discover about subacromial
compressive forces during shoulder elevation?
compressive forces are 42% of body weight
At what angles of shoulder elevation are subacromial compressive forces the highest?
between 85° and 136° of elevation
What phases of the throwing motion are most likely to produce subacromial compression?
acceleration and follow-through
What are the shoulder motions during the follow-through phase of throwing that cause subacromial compressive forces?
flexion, horizontal adduction, and internal rotation
What musculotendinous structures are most likely to experience abrasion due to subacromial impingement/compression during the throwing motion.
supraspinatus, infraspinatus, or biceps tendon
According to Neer, what are the 3 stages of primary rotator cuff impingement?
- Stage I: edema and hemorrhage
- Stage II: fibrosis and tendonitis
- Stage III: bone spurs and tendon rupture
What is Stage I Primary Rotator Cuff Impingement?
a.k.a edema and hemorrhage
- mechanical irritation of tendon via impingement during overhead activity
- reversible with PT
Describe the typical profile and clinical presentation of a patient with stage I primary rotator cuff impingement.
- young, athletic patients
- painful arc
- (+) impingement sign
- varying degrees of muscular weakness
What is Stage II Primary Rotator Cuff Impingement?
a.k.a fibrosis and tendonitis
- repeated episodes of inflammation
- thickening/fibrosis of the bursa
- ages 25-40