Shoulder Flashcards
AC joint injury grading
downward blow to lateral shoulder
ligament sprain –> disruption of AC joint capsule and coraclavicular ligaments
- Grade I: AC ligament sprain. Radiographs are normal.
- Grade II: Disruption of the AC ligament with intact CC ligaments.
- Grade III: AC joint and CC ligamentous disruption. CC interspace is widened 25–100% relative to the contralateral side.
- Grade IV: Distal clavicle displaced posteriorly into trapezius (seen on CT or axillary view).
- Grade V: Severe grade III injury, with >100% displacement relative to the other side.
- Grade VI: Inferior dislocation of the distal clavicle.
normal AC joint space , CC joint space
< 5 mm, 11-13 mm
MOA anterior shoulder dislocation? posterior?
direct force on arm; antero-inferior direction
severe muscle spasm (seizure/electrocution)
best view for anterior shoulder dislocation? posterior?
anterior: axillary view
posterior: transscapular Y view or axillary view ; overlap on Grashey vew
site of impaction fracture on humerus head/glenoid
anterior inferior glenoid
posterolateral humeral head
Hill sachs lesion, bankart, reverse bankart? ?
Hillsachs: compression fracture of humerus
Bankart: anterior inferior glenoid rim
Reverse bankart: posterior glenoid (posterior dislocation)
lightbulb sign? trough sign?
shoulder dislocation
- The lightbulb sign describes the appearance of the humeral head due to the fixed internal rotation of the arm often seen in posterior dislocation.
- The trough sign describes a compression fracture of the anteromedial aspect of the humeral head, also known as a reverse Hill–Sachs, from impaction of the humeral head on the posterior glenoid rim upon recoil.
luxatio erecta
inferior dislocation of shoulder from direct force on abducted arm
asociated with rotator cuff tear, greater tuberosity fracture; injury to axillary nerve/artery
do subacromial and subdeltoid bursa communicate? communicate with glenohumeral joint?
clinical impact?
yes, no
arthrogram fluid will extend from glenohumeral joint into bursa with rotator cuff tear
impingement syndrome
chronic compression/irritation of structures that pass through the coracoacromial arch (supraspinatus/biceps tendon, subacromial-subdeltoid bursa)
extrinsic impingement shoulder
-primary external impingement: variant coracoacromial arch (subacromial enthesiophyte, hooked acromion, ac joint osteophyte, thickened coracromial ligament, os acromiale)
subcoracoid impingement: coracohumeral distance narrows
intrinsic impingement shoulder
glenohumeral instability; abnormalities of the rotator cuff/joint capsule
types of acromion shapes, classification
Borliani
type I: flat
type II: curved
III: hooked
IV: convex undersurface
III/IV may cause external impingement –> rotator cuff tear
frequency of os acromiale
15%; best seen axial view
rotator cuff muscles
SITS: supraspinatus, infraspinatus, teres minor, subscapularis
insertion site of SITS
SIT: body of scapula and insert on greater tuberosity
subscapularis: anterior to scapula; lesser tuberosity
mucoid degeneration of tendon; without inflammation
tendinosis/tendinopathy
MR signal of tendinosis
thickening; T1/T2 intermediate signal
magic angle appears on what sequences?
short TE sequences (T1, PD, GRE)
what happens to bursa/joint in shoulder with complete tear
suacromial-subdeltoid bursa and glenohumeral joint communicate
what is the footprint? critical zone?
attachment of tendons at greater tuberosity
potential undervascularized portion of distal supraspinatus tendon (1 cm proximal to insertion on footprint)
most commonly injured rotator cuff muscles?
supraspinatus > infraspinatus »_space; teres minor
best way to diagnose partial thickness tear?
MR arthrography to show communication of fluid between glenohumeral/subacromial-subdeltoid bursa
partial thickness tear shows abnormal signal in muscle/tendon that does not extend through entire thickness
types of partial tears? most common type?
bursal, articular, intrasubstance tear
articular surface
most common type of partial tear?
rim rent or PASTA (partial thickness articular supraspinatus tendon avulsion)
what is PAINT tear?
partial articular tear with intratendinous extension; partial rotator cuff tear at articular surface that also extends into tendon
most common full thickness tear? associated tear?
supraspinatus
30-40% supraspinatus tears associated with infraspinatus
rheumatoid arthritis rotator tuff tear ?
migrated superiorly; acromion articulation
classification of full thickness tears?
length of tendon affected
Goutallier classification?
rotator cuff atrophy; degree of fatty replacement in the SITs muscles
how quickly does rotator cuff atrophy occur?
within 4 weeks of injury, usually irreversible
extent correlates with outcome following surgical repair
association with denervation atrophy?
paralabral cyst
frozen shoulder?
adhesive capsulitis; thickening/contraction of glenohumeral joint capsule due to inflammation of the joint capsule/synovium
MR findings of adhesive capsulitis
joint capsule/synovial thickness >4mm at the axillary pouch
what is the rotator interval?
triangular region that allows rotational motion around coracoid process
borders: supraspinatus and subscapularis
contents of rotator interval?
coracohumeral ligament (CHL), long head bicepts tendon, superior glenohumeral ligament
what is biceps pulley?
intraarticular biceps tendon + CHL + superior glenohumeral ligament (SGHL)
is CHL internal or external to joint capsul?
external?
connection of SGHL?
lesser tuberosity to supraglenoid tubercle of scapula
connection of MGHL? always present?
lesser tuberosity to supraglenoid tubercle of scapula
congenitally absent 30% pts
association with tear of MGHL?
superior labral tear
connection of IGHL? role?
anatomical neck of humerus to inferior glenoid labrum.
important for stability in abduction/external rotation
components of IGHL
anterior band, axillary pouch, posterior band (seen on sagittal)
connection of LHBT
anterosuperior glenoid rim along with the SGHL and MGHL
biceps tendon origin
superior labrum along intertubercular groove; communicates with glenohumeral joint
capsuloligamentous complex that stabilizes the biceps tendon?
biceps pulley; SGHL, CHL, subscapularis tendon
biceps tendon tear association?
supraspinatus tear
complication in biceps with supraspinatus tear?
impingement
association with biceps tendon subluxation?
injury to transverse ligament (which insert at greater/lesser tuberosities to hold tendon in place)
best view biceps tendon dislocation?
association with biceps tendon dislocation?
axial MRI –bicipital groove is empty
injury to subscapularis tendon; injury of transverse ligament/pulley
(bicep tears associated with supraspinatus injury)
shoulder instability types
atraumatic: AIOS (acquired, instability, overstress, surgery) OR AMBRI (atraumatic, multidirectional, bilateral, rehabilitation, inferior capsule shift) congenital joint laxity
traumatic: TUBS, (traumatic, unidirectiona, bankart, surgical)
most common instability of the shoulder?
anterior instability
classification of labral injury
using sextants or clock face
role of the labrum?
fibrocartilage that surrounds glenoid and increases surface/depth of glenoid cavity (suction effect)
labral variants
sublabral foramen: anterosuperior segment is not attached to the bony glenoid.
Buford complex : ormal variant where a cord-like middle glenohumeral ligament is seen in combination with an absent anterosuperior labrum.
bankart lesion vs osseous bankart location
anteroinferior labral injury from anterior glenohumeral dislocation; stripping of scapular periosteum
fracture of anterior-inferior glenoid rim; predisposition to recurrent dislocation
GLOM sign
glenoid labrum ovoid mass sign; labrum migrates superiorly
ddx for black intraarticular mass
GLOM sign, dislocated biceps tendon, air bubble if MR arthrogram
Hill sachs location
posterolateral humeral head; anterior dislocation
How to find a hill sachs lesion
axial images; normal humeral head is round on 3 consecutive slices
posterolateral notch in humeral head, bone marrow edema
what does ALPSA stand for?
anterior labro-ligamentous periosteal sleeve avlusion; Bankart variant from anterior-inferior labral injury
scapular periosteal is intact
which way is labrum displaced in ALPSA?
inferomedially; GLOM sign is superiorly displaced
What is perthes lesion?
avulsion of anterioinferior labrum; labrum attached to scapular periosteum
best view for perthes lesion?
ABER: abduction, external rotation
HAGL? opposite what lesion?
humeral avulsion of the inferior glenohumeral ligament at attachment of IGHL
opposite to Bankart, ALPSA, Perthes
BHAGL?
bony HAGL from avulsion of anatomic neck of humerus
posterior instability lesions
posterior HAGL (PHAGL), reverse bankart, reverse Hill Sachs/trough sign
what muscle tears associated with posterior injuries?
infraspinatus, teres minor (insert on posterior aspect of greater tuberosity)
congenital cause for posterior instability?
hypoplastic posterior glenoid
thrower’s exostosis
extra-articular posterior ossification associated with posterior labral injury (Bennet lesion)
SLAP lesion acronym
superior labrum anterior posterior tear; AP oriented tear of the superior labrum centered at biceps tendon
SLAP classification, most frequent type ?
4 originally, now up to 10
I: fraying of superior portion of labrum ,no frank tear, biceps intact
II: most frequent ; labray fraying with stripping of superior labrum (repetitive microtruam)
III: bucket handle tear
IV: buket handle tear with extension into biceps tendon
GLAD
glenoid labral articular disruption; superficial tear of anterior inferior labrum
complications of GLAD
posttraumatic arthritis, intra-articular bodies
GLAD occurs at same site as?
anterior inferior labrum
same as Bankart, ALPSA, perthes
paralabral cysts cause? complication?
labral tears; soft tissues adjacent the labrum but may extend into bone
specific finding for labral tear; may cause entrapment neuropathy if they cmopress a nerve
quadrilateral space syndrome?
posterior aspect of axilla, can result in axillary nerve entrapment –> teres minor paresthesi and atrophy; deltoid can be involved
borders of quadrilateral space ? contains?
humerus, triceps, teres minor, teres major
contains the axillary nerve, posterior humeral circumflex artery
innervation to supraspinatus and infraspinatus muscle
proximal suprascapular nerve; distal suprascapular nerve provides motor innervation to infraspinatus muscle only
where does suprascapular nerve get entraped? cause?
suprascapular notch; entrapment commonly from paralabral cyst with superior labral tear
innervation to infraspinatus muscle?
distal supraspinatus nerve
isolated atrophy of infraspinatus, cause?
entrapment of distal suprascapular nerve at spinogelnoid notch
