Shoulder Instability Basics

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Shoulder Instability Basics

• 18 February 2010

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Contents

• Terminology
• Anatomy
• Pathophysiology
• Evaluation
• Nonoperative Treatment
• Operative Treatment
• Treatment Course/Outcomes

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Terminology

• Laxity
• Asymptomatic, passive translation of the humeral
  head on the glenoid unassociated with pain
• Instability
• Symptomatic pain/apprehension associated with
  excessive translation of the humeral head during
  active motion

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Shoulder Anatomyand Function
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Skeletal Anatomy
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Skeletal Anatomy
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Osteology

• Glenoid version
• 30o anterior
• Humerus
• Neck-shaft 130o to 140o
• Retrotorsion 30o

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Superficial Anatomy
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Rotator Cuff Anatomy
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GHJ Anatomy
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GHJ Anatomy (contd)
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Labrum

• Fibrocartilaginous ring
• Anchors capsuloligamentous structures
• Deepens the glenoid
• Doubles depth
• Increases Surface area

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SGHL

• Most constant ligament but variable thickness
• 3 variations of origin
• Inserts into top of humerus near tip of lesser
  tuberosity

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Function-SGHL

• Limit inferior translation and external rotation
  when arm is adducted
• Limit posterior translation when the arm flexed,
  add, IR

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Rotator Interval

• Triangular area of tissue
  from supraspinatus superiorly to subscapularis
  inferiorly
• Capsule thickened by SGHL CH lig
• Defects - ?? Significance

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MGHL

• Most variable
• Sheetlike or cordlike
• Originates from labrum or neck of glenoid just
  inf to SGHL
• Inserts just medial to lesser tub closely opposed
  to subscap

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Function

• Limits anterior translation with 60o to 90o
  abduction and ER
• Limits inferior translation with
  the arm adducted

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IGHL

• Anterior band, axillary pouch, posterior band
• Originates from labrum/glenoid neck
• Ant band 2 to 4 oclock
• Post band 7 to 9 oclock
• Inserts into anatomic neck humerus 90o arc

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Function

• Limits anterior, posterior, and inferior
  translation depending on arm position
• aIGHL limits AP translation in ext, pIGHL limits
  AP translation in flex

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Capsuloligamentous Structures
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Instability Pathophysiology

• Most motion of any joint
• Dynamic and Static Restraints
• Bankart lesion
• Avulsion of IGHL Labrum complex
• HAGL

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Stability

• Static Factors
• Articular Congruence
• Articular Version
• Glenoid Labrum
• Capsule and Ligament

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Pathology-version

• Glenoid dysplasia
• 1 to 3 of instability cases
• Avoid surgery

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Glenoid Rim Fracture

• Reduces contact area and glenoid concavity
• Less than 25 to 33 involvement not a problem if
  IGHL is reattached

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Hill-Sachs Lesion

• Impression fracture of posterolateral humeral
  head
• Little consequence if soft tissue repair is
  performed
• Some say greater than 30 involvement may lead to
  continued instability

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Bankart Lesion

• Detachment of anteroinferior labrum
• IGHL is key
• Essential lesion??
• Speer, et al JBJS 76A, 1994

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Capsular Injury

• Acute tears
• HAGL lesion
• Plastic deformation
• Bigliani, et al JORS, 1992
• Circle concept
• Need for capsular shift failure of scope repairs

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Stability

• Dynamic Factors
• Rotator Cuff
• Biceps Tendon
• Negative Pressure
• Scapulothoracic motion

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Rotator Cuff

• Compression enhances conformity
• Greater than static stabilizers
• Coordinated contractions/steering effect
• Supraspinatus most important
• Dynamization

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Scapulothoracic Motion

• 21 glenohumeral to scapulothoracic motion
• Scapulothoracic muscle (trapezius, serratus
  anterior) weakness produces winging less
  stable platform

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Negative Intra-articular Pressure

• -42 cm H2O in cadaver
• Secondary to high osmotic pressure in
  interstitial tissues
• Only clinically important in the arm at rest in
  adduction
• with lax capsule or defect

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Stability

• Static Factors
• Articular Congruence
• Articular Version
• Glenoid Labrum
• Capsule and Ligament

• Dynamic Factors
• Rotator Cuff
• Biceps Tendon
• Negative Pressure
• Scapulothoracic motion

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Instability Categories

• TUBS
• Traumatic
• Unidirectional
• Bankart lesion
• Surgery

• AMBRII
• Atraumatic
• Multidirectional
• Bilateral
• Rehabilitation
• Inferior capsule
• Interval closure

Thomas Matsen, JBJS(1989)
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Multidirectional Instability

• Definition
• symptomatic increased translation of humeral head
  on glenoid.
• Can be subluxated or dislocated, in three
  directions with reproduced symptoms with one or
  more of these directions.

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MDI

• No Single Etiology
• Inherent Ligamentous Laxity
• Trauma (Major/Repetitive Minor)
• Scapular Mechanics

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A Spectrum

• Traumatic Microtrauma Atraumatic
• Less laxity More
  laxity
• Unidirectional
  Multidirectional

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Instability

• Classification
• Frequency
• Direction
• Degree
• Etiology

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Classification

• Frequency
• Acute
• Recurrent
• Fixed (chronic)
• Cause
• Traumatic event (macrotrauma)
• Atraumatic event (voluntary, involuntary)
• Microtrauma
• Congenital condition
• Neuromuscular condition (cerebral palsy, seizures)

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Instability

• Patient Evaluation

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History

• Position of Instability
• Traumatic/Atraumatic
• Onset of Symptomsgt
• Need for Reduction
• Psychiatric Component
• Family History

• Inf. Instab. pain with carrying
  suitcase/shopping bags _at_ side
• Ant. Instab. throwing, reaching objects
  ABD/ER
• Post. Instab. pushing heavy doors FF/IR

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Anterior Instability

• Traumatic, acute, dislocation
• Traumatic, acute, subluxation
• Recurrent anterior instability
• Chronic recurrent anterior dislocations
• Chronic recurrent anterior subluxation
• Fixed (locked) anterior dislocation

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Posterior Instability

• Traumatic acute dislocation
• Traumatic acute subluxation
• Recurrent posterior instability
• Recurrent posterior dislocation
• Recurrent posterior subluxation
• Voluntary
• Positional
• Muscular
• Chronic (locked) dislocation
• lt25 of articular surface
• 25-40 of articular surface
• lt40 of articular surface

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Multidirectional Instability

• Type I - Global, atraumatic, instability
• Type II - Anterior/inferior instability
• Macrotrauma in setting of hyperlaxity
• Type III - Posterior/inferior instability
• Microtrauma in setting of hyperlaxity
• Type IV - Anterior/posterior instability

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Clinical Evaluation - History

• Careful history is paramount
• 1st episode of dislocation or subluxation
• Degree of trauma - major, trivial, none
• Dislocation vs. subluxation
• Position of arm
• More frequent episodes
• Treatment

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History - Present Symptoms

• Arm slips out
• Dead arm syndrome
• Pain
• Anterior/posterior pain ant/post instability
• Pain in context of arm position
• Cocking vs. follow-through
• Carrying heavy items
• Secondary impingement
• Popping/clicking

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History- contd

• Functional losses
• ADLs vs. sports
• Activity modification
• Voluntary control
• Positional
• Muscular

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Physical Examination

• Inspection
• Palpation/ROM
• Ligamentous laxity
• Load-Shift test
• Apprehension test/ Relocation test
• Sulcus sign
• RC pathology

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Physical Examination

• Examine both shoulders
• Cervical spine
• Generalized ligamentous laxity

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Generalized Joint Laxity Tests

• Passive thumb apposition
• Passive finger hyper-extension so finger
  parallels forearm
• Elbow hyper-extension gt10 degrees
• Knee hyper-extension gt10 degrees
• Excessive ankle dorsiflexion and foot eversion

Carter and Wilkinson in (Brown CORR, 2000)
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Shoulder Exam

• Muscular atrophy
• Tenderness
• AC and SC joint tenderness
• ROM - active passive
• Winging
• Muscle strength
• Supraspinatus - 90o scap elevation/45o int rot
• Infraspinatus - 0o scap elevation/ -45o rot
• Subscapularis - lift-off/ Napoleans
• Deltoid/Biceps/triceps/trapezius

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Anterior Apprehension Test
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Relocation Test
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Posterior Apprehension
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Load and Shift Test

• Grade I - to the glenoid rim
• Grade II - Over the rim, spontaneous reduction
• Grade III - Remains dislocated

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Sulcus Sign

• 1 Less than 1 cm
• 2 1-2 cm
• 3 Greater than 2 cm
• Pathognomonic of MDI
• Neutral vs. ER

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Imaging Studies

• Radiographs
• True AP Glenohumeral joint
• Trans Scapular Y
• Axillary
• West Point axillary
• Stryker notch view

• Arthrography
• CT
• MRI

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True AP Scapular Y
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Axillary and West Point
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Stryker Notch View
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Get an Axillary!
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Computed Tomography
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Magnetic Resonance Imaging
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Diagnostic Arthroscopy
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Arthroscopic Pathology

• Bankart lesion 80-90
• Hill-Sachs lesion 80
• Other signs
• Labral wear, splitting, blunting
• Chondral injuries
• Patulous capsule
• HAGL lesion
• SLAP posterior cuff
• Drive through sign

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Treatment
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First Time Dislocation

• Mechanism
• Bony Defects
• Genetics
• Future goals
• AGE

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Nonoperative Treatment

• Rest/ Brief immobilization
• NSAIDS
• Exercise program 6 months minimum, indefinite
  maintenance esp. MDI
• Resistance exercise
• Proprioception exercises
• Rockwood and Burkhead (JBJS 1992) 80
  satisfactory results with atraumatic subluxation

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Instability- Operative Treatment
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MDI -Operative Treatment

• Indications
• Symptomatic
• Involuntary
• Global glenohumeral instability
• Six month nonoperative exercise compliance

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MDI -Operative Treatment

• Contraindications
• Voluntary dislocation
• Psychiatric history
• Neurologic injury (Ax and SS nerves)
• Glenoid aplasia/hypoplasia

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Instability Procedures

• Soft tissue defects
• Open Inferior Capsular Shift
• Arthroscopic Capsular Shift
• Thermal Capsulorrhaphy
• Bony Defects
• Humerus
• Glenoid

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Postoperative Management

• Six Weeks Immobilization
• Progressive Resistance Exercises
• Go Slowly
• Repair Failure versus Stiffness

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Complications

• Recurrent instability
• Opposite direction subluxation
• Poor patient selection

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Outcomes
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Open Capsular Shift

• Altchek and associates (JBJS 1991)
• Bigliani and associates (AJSM 1994)
• Bak and associates (AJSM 2000)
• Pollock and associates (JBJS 2000)

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Arthroscopic Technique

• Altchek and assoc. (JBJS 1991)
• Gartsman and assoc. (Arthroscopy 2001)
• Nelson and assoc. (AJSM 2000)

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Thermal Capsulorrhaphy

• Savoie and assoc. (Arthroscopy 2001)
• Rotator interval capsule doesnt respond well
  to shrinkage - Plication with sutures

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Questions??