MR Imaging of Glenohumeral Instability

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MR Imaging of Glenohumeral Instability

• Timothy G. Sanders, M.D.
• Assistant Professor
• Uniform Services University
• Bethesda, MD

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Glenohumeral Joint

• Intrinsically Unstable joint
• Shallow glenoid fossa
• Large articular surface of the humeral head
• Static Stabilizers
• Joint capsule
• Glenohumeral Ligaments
• Glenoid labrum
• Dynamic Stabilizers
• Rotator cuff
• Tendon of the long head of the biceps

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Classification

• TUBS
• Traumatic
• Unidirectional
• Bankart
• Surgery

• AMBRI
• Atraumatic
• Multidirectional
• Bilateral
• Rehabilitation
• Inferior Capsular Shift

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Multidirectional Instability

• AMBRI Patient
• Causes of Multidirectional Instability
• Hypermobility or Laxity
• Stretching or Overuse of Support Structures
• MR Imaging not usually Required
• MR Findings Nonspecific
• MR Useful if Direction Unknown to Rule Out
  Conventional Causes

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Anterior Stabilizers

• Labrum
• Glenohumeral Ligaments
• Capsule
• Subscapularis Muscle
• Most Important Anterior Stabilizer Inferior
  Glenohumeral Labroligamentous complex
• Anteroinferior labrum
• Anterior Band of the Inferior Glenohumeral
  Ligament

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Normal Labrum
Anterior and Posterior Labrum best seen in the
Axial Plane
LABRUM -Dark on all Pulse Sequences -May be
triangular, rounded, or blunted
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Normal Superior Labrum
Seen Best in the Coronal Plane
Superior Labrum -Dark on all pulse
sequences -Triangular -Extends off of Superior
Glenoid
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Glenohumeral Ligaments
Superior GH Ligament
Middle GH Ligament
Anterior Band of the Inferior GH Ligament
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Superior Glenohumeral Ligament
-Prevents inferior subluxation with arm in 0º
abduction
-Courses from superior glenoid tubercle to lesser
tuberosity -Parallels Coracoid process
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Middle Glenohumeral Ligament
-Prevents external rotation of humeral head when
arm is between 45º and 60º of abduction
-Originates at superior glenoid tubercle
-Courses obliquely superficial to the anterior
labrum -Blends with the deep fibers of
subscapularis
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Middle Glenohumeral Ligament
Most Variable of the GH Ligaments
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Inferior Glenohumeral Ligament
-Most important GHL -Prevents anterior
subluxation with arm in full abduction and
external rotation
-Extends from anterior inferior labrum to humeral
neck
-Lax with arm in neutral position
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Inferior Glenohumeral Ligament
-Redundant when the Arm is in Neutral Position
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ABER Positioning
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Scout Position and Scan Plane for ABER
-Coronal scout with arm in ABER position
-Scan plane along the long axis of the humeral
shaft
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Inferior Glenohumeral Ligament ABER Imaging
-Provocative position -Stretches the anterior
band of IGHL and places tension on the anterior
labrum -Helps in the identification of subtle
nondisplaced anterior labral tears
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Normal Anatomic Variants
Cartilage Undermining
-Articular Cartilage Hyaline- Intermediate -Labrum
- Fibrocartilage Dark Signal
-Smooth, tapering -Does not Extend Completely
Beneath Labrum
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Normal Anatomic Variant
Labral Tear
Cartilage Undermining
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Normal Anatomic Variants
Sublabral Foramen (Hole)
-Complete detachment of the labrum from the
glenoid -Occurs only in the anterosuperior
quadrant
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Normal Anatomic Variant
Sublabral Recess
-Smooth, Tapering -Extends Toward the Glenoid
-No Signal Extends into the Black Triangle of the
Superior Labrum -Can Mimic a SLAP Tear
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Normal Anatomic Variant
Sublabral Recess
-Axial Plane -Smooth Linear collection of
Contrast between Superior Labrum and Osseous
Glenoid
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Normal Anatomic Variant
-Buford Complex -1.5 of Patients -Can Mimic
Anterior Labral Tear
-Thick Cord-like MGHL
-Absent or Diminutive Anterior-Superior Labrum
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Buford Complex
1
2
3
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Anterior Instability

• 95 of all Dislocations
• Mechanism
• Fall on an outstretched arm
• Abduction and external rotation

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Bankart Lesions

• The Most Common Injury Following Anterior
  Dislocation
• First-Time Dislocators Under 35 y.o.
• Anterior Labro-Ligamentous Avulsion with
  Disruption of the Medial Scapular Periosteum

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Bankart Lesion
1. Anterior labroligamentous avulsion
2. Disruption of the medial scapular periosteum
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Bankart Lesion
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Osseous Bankart
-Fracture of Inferior Glenoid -Disruption of the
Cortex of the Anteroinferior Glenoid
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Hill-Sachs Lesion
-Results from Impaction of Humeral Head against
Anterior-inferior Glenoid -Associated with
Bankart Lesion -Normally Top 3 Images
Round -Hill-Sachs Flattening or Concavity
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Double Axillary Pouch Sign
-Normal anteroinferior labrum on coronal image
-Double axillary pouch Small collection of
contrast in inferior labrum
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Double Axillary Pouch Sign
-Normal anteroinferior labrum on coronal image
-Double axillary pouch Small collection of
contrast in inferior labrum
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Perthes Lesion Nondisplaced Bankart

• Bankart Variation
• Labro-Ligamentous Disruption
• Medial Scapular Periosteum Intact
• May Resynovialize in Place
• Best Detected on ABER View

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Perthes Lesion
1. Anterior labroligamentous avulsion
2. Medial scapular periosteum remains
intact --Nondisplaced Bankart
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Nondisplaced Tear Anteroinferior Labrum
Cartilage Undermining
Perthes Lesion
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ABER Positioning
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Perthes Lesion
Normal Anteroinferior Labrum
Nondisplaced Labral Tear
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ALPSA Lesion Medialized Bankart

• Anterior Labroligamentous Periosteal Sleeve
  Avulsion
• Intact Medial Scapular Periosteum
• Medialized Bankart Lesion
• Surgical Repair Technique Differs From Bankart

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ALPSA Lesion
Medialized Bankart
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Medialized Bankart Lesion
ALPSA
-Avulsed Labrum Pulled Medially by an intact
Medial Scapular Periosteum -Easily Identified in
the Acute Setting
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Chronic Medialized Bankart Lesion
-Labrum scars down medially
-Scar tissue mounds up covering medialized labrum
and resynovializes -Treatment complete Bankart
and reconstruction
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Axillary Nerve Neuropraxy
Axillary Nerve can be stretched at time of
anterior dislocation resulting in denervation
atrophy Deltoid and Infraspinatus muscles
Denervation atropy -Acute edema -Chronic fatty
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First Time Dislocation Over Age 35

• Clinical Presentation can be Confusing
• Tear Supraspinatus Tendon
• Fracture Greater Tuberosity
• Avulse Subscapularis and Anterior Capsule from
  the Humerus
• MRI can Play Pivotal Role in Directing Patient
  Therapy

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Tear of the Supraspinatus Tendon
First Time Dislocation Over Age 35 Bankart
Lesion is Uncommon
Rotator Cuff becomes the Weak Link
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First Time Dislocation Over Age 35
Avulsion fracture of the greater tuberosity
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Greater Tuberosity Fracture
-Avulsion of the Greater Tuberosity is often
Occult Radiographically -Can Mimic RCT
-Treated Conservatively -MRI can Accurately
Distinguish
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Avulsion of Subscapularis
-Subscapularis Muscle can Avulse off of Lesser
Tuberosity -Associated with Dislocation of the
Biceps Tendon -Seen best in Axial Plane
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Disruption of Subscapularis
-Disruption of Subscapularis at Musculotendinous
Junction -Requires Surgical Repair
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HAGL LESION

• Humeral Avulsion of the Glenohumeral Ligament
• Results from Dislocation
• No Age Predilection
• MR Findings Contrast Extravasation from Joint
  Capsule/ Avulsion of Subscapularis

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HAGL Variants
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HAGL Lesion
Disrupted IGHL at humeral attachment site
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HAGL Lesion
-Inferior GHL can Disrupt Anywhere Along
Course -Humeral Attachment/ Mid Substance
-Difficult to Detect with Scope -Cause of Failed
Repairs
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HAGL Lesion
-Can Present on MRI as Avulsion of Subscapularis
Muscle
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Posterior Instability

• 2 - 4 of all traumatic dislocations
• 20 - 25 of shoulder instability cases in active
  duty military population
• Adduction with internal rotation
• Seizure, electrocution, weight lifting, swimming,
  lineman blocking
• Reverse Hill Sachs, Bankart

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Posterior Instability
Reverse Bankart
Reverse Hill Sachs
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Posterior Instability
-Repetitive Microtrauma Nondisplaced posterior
labral tear
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GLAD Lesion

• Glenolabral Articular Disruption
• Forced adduction injury (humeral head impacts the
  glenoid fossa)
• Clinically a Stable Lesion
• Partial Tear Anteroinferior Labrum / Articular
  Cartilage Injury

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GLAD Lesion
-Non displaced tear anteroinferior labrum
-Articular Cartilage Injury
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GLAD Lesion
-Non displaced tear anteroinferior labrum -Best
seen on ABER
-Articular Cartilage Injury -Best seen on axial
or coronal
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Posterior Superior Glenoid Impingement

• Also known as Internal Impingement
• Undersurface tearing of posterior rotator cuff
  (posterior SST or IST)
• Impingement between posterior labrum and greater
  tuberosity
• Throwing athletes- posterior shoulder pain
• Associated with anterior instability

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Posterior Superior Glenoid Impingement
-Undersurface of posterior rotator cuff impinged
between the greater tuberosity and the
posterosuperior labrum -Seen best on ABER view
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Posterior Superior Glenoid Impingement
1) undersurface tear of posterior rotator cuff
2) degenerative changes of posterosuperior labrum
3) cystic change in greater tuberosity
4) internal impingement seen on ABER view
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Glenohumeral Internal Rotation Deficit (GIRD)
-Scarring and thickening of the posterior capsule
and has recently been described as a source of
potential pain in throwing athletes - MR imaging
demonstrates thickening of the posterior capsule
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SLAP Tears

• The Superior labrum, anterior-to-posterior
  lesion, can include biceps tendon
• Mechanism
• Fall on outstretched arm
• Repetitive overhead activity (throwing, swimming)
• Symptoms pain with overhead activity, catching,
  popping sensation

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SLAP Tear Type I
Fraying of the undersurface of the superior labrum
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SLAP Tear Type II
Avulsion of the labrum from the osseous glenoid
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SLAP Tear Type III
Bucket handle tear of the superior labrum
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SLAP Tear Type IV
Extension of the SLAP tear to involve the biceps
anchor
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Important factors to observe

• Abnormal signal in superior labrum
• Extent of lesion
• Posterior labrum
• Anteroinferior quadrant
• Biceps involvement
• Type of SLAP tear

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SLAP Lesion
-Normal Superior Labrum -No internal Signal
-TYPE 1 -Fraying and degeneration but labrum
firmly attached
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SLAP Lesions
-TYPE 2 -Fraying of labrum and superior labrum
avulsed from glenoid
-Signal extends into the triangle of the superior
labrum
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SLAP Lesions
-TYPE 3 -Bucket-handle tear of the superior
labrum Biceps tendon remains intact
-On MR imaging Fragment seen displaced into
superior joint space
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SLAP Lesions
-TYPE 4 -Bucket-handle tear of superior labrum
involves biceps anchor
-Biceps involvement best seen on axial/coronal
images
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Pitfalls SLAP Tears
-SLAP tear -Any signal extending into black
triangle
-Sublabral recess -Smooth, tapering -No signal in
sup labrum
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Pitfalls SLAP Tears
-SLAP on axial images -Irregular contrast
collection
-Sublabral recess axial images -Smooth linear
collection of contrast
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Pitfalls SLAP Tears
-Sublabral recess -No displacement of sup labrum
-Type 2 SLAP tear -Labrum pulled away from glenoid
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Paralabral Cyst

• High association with labral tears and GH joint
  instability
• Superior labral cyst SLAP tears
• Posterior labral cyst Posterior labral tears
• Labral tear may resynovialize
• Can result in shoulder pain and adjacent nerve
  entrapment

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Paralabral Cysts
-Suprascapular nerve entrapment -Denervation
edema
-SLAP tear with superior paralabral
cyst -Suprascapular notch
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Paralabral Cysts
-Posterior paralabral cysts -Extend into
spinoglenoid notch -Entrapment of suprascapular
nerve
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Paralabral Cysts
-Persistent shoulder pain for 3 years -Small
anterior labral tear with small adjacent
paralabral cyst
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Paralabral cysts
-3 years later persistent pain -Paralabral cyst
larger -Axillary nerve entrapment -Atrophy Teres
Minor
-Small inferior labral cyst -Teres Minor normal
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Labral RepairSurgical Approach

• Direct repair of labral and capsular lesions
• Indirect repairs
• Staple capsulorapphy (Du Toit Roux)
• Subscapularis manipulation to tighten anterior
  capsule (Putti Platt/ Magnuson Stack)
• Movement of the coracoid process (Bristow
  procedure)

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Direct Repairs

• Arthroscopic/ open (deltopectoral interval)
• Suture anchors 3-,4-,5-, oclock position
• Capsulorapphy (open/ arthroscopic)
• Staple redundant capsule
• Done in conjunction with direct repair
• High failure rate if done as isolated procedure
• Osseous Bankart
• Screw fixation

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MR Findings of Bankart Repair

• Suture anchor artifact from repair may obscure
  visualization

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MR Findings of Failed Bankart Repair

• Recurrent displaced anterior labrum

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Failed Bankart Repair

• Missed HAGL lesion
• In one series up to 30 of failed repairs

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Subscapularis Tendon Transfer (Magnuson-Stack)

• Repositioned subscapularis tendon
• Labral pathology still evident (indirect)

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Putti - Platt
MR Findings -Thick anterior capsule -OA -Original
instability lesion still present

• Subscapularis tendon split lateral portion
  attached to glenoid medial portion is imbricated
  over it
• Dec ROM poor pt satisfaction recurrence 2-10

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Bristow Repair

• Move coracoid process to cause bone block to
  prevent ant dislocation
• Attached to anterior inferior glenoid

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Recurrent SLAP Following Repair

• Displaced fragment anterosuperior labrum
• Osteochondral defect anterosuperior glenoid

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5 Months Following SLAP Repair Recurrent Pain

• Fraying and irregularity of superior labrum no
  displaced fragment
• Partial thickness articular surface tear rotator
  cuff

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Multidirectional Instability

• Treated first with rehabilitation
• Surgery
• Inferior capsular shift/plication
• Decrease volume of GHJ anteriorly, inferiorly,
  posteriorly
• MR capsular thickening

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Multidirectional Instability

• Treated first with rehabilitation
• Surgery
• Inferior capsular shift/plication
• Decrease volume of GHJ anteriorly, inferiorly,
  posteriorly
• MR capsular thickening

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Hardware Failure
Displaced tack
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Hardware Complication
Proud suture anchor
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SynovitisPrior SA Decompression and Rotator Cuff
Debridement Recurrent Pain

• Synovitis 4 mm adhesive capsulitis
• Normal postop capsule
• 2-4 mm after surgical procedure
• Thickened and nodular capsule

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Postop Infection

• Infectious versus reactive synovitis difficult to
  differentiate with imaging
• Thickened enhancing capsule effusion/ joint
  destruction/ cartilage loss/ cysts, erosions