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Shoulder Instability Jeff Johnson
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The Amazing Human Body
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Shoulder Most mobile joint in the body
Minimally constrained articulation that must balance mobility with stability Not always successful, as it is the most likely joint to dislocate
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Laxity vs. Instability Laxity: Asymptomatic passive translation of humeral head on the glenoid Instability: Excessive symptomatic translation of humeral head on glenoid during active motion
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Definition of Terms Direction: Anterior vs. Posterior vs. MDI
Timing: Acute vs. Chronic Frequency: Single vs. Recurrent Etiology: Traumatic vs. Atraumatic Degree: Subluxate vs. Dislocate Volition: Voluntary vs. Involuntary
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The Stable Shoulder Static Restraints Dynamic Restraints Bone
Glenoid Humerus Ligaments Labrum Capsule Negative pressure Adhesion/cohesion Dynamic Restraints Rotator Cuff Concavity compression Biceps Deltoid Scapula Rotators
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Static: Bone Glenoid Articular Version Bone loss
30° anterior on Chest wall 3° upward tilt 7° retroversion (25% of people of anteversion 2-10°) Bare spot in the center and more cartilage in periphery (increases the depth) Bone loss Fracture Dysplasia
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Static: Bone Humerus Version Articular Surface
130° neck shaft angle 30° retroversion Articular Surface More of sphere in the center and elliptical in the periphery In any position, there is only 25-30% of the humeral head in contact with the glenoid Importance of soft tissue for stability Congruity Almost a perfect match with glenoid (<3mm) Behaves like a ball and socket joint with < 2mm translation Congruity less important than total surface area Hill-Sachs Reverse Engaging
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Static Restraints Labrum Anchor for capsule & ligaments
Deepens the concavity of the socket Increases depth of socket by 50% (5-9mm) Increases surface area Load bearing? Bumper or “Chock Block” Resection decreases resistance to translation by 20%
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Static Restraints Capsuloligaments
Coracohumeral ligament Primary restraint to inferior translation of the ADDucted arm and to ER SGHL Primary restraint to ER in ADDucted or slightly abducted arm Primary restraint to inferior translation in the ADDucted arm MGHL (absent in 30-40%) Primary stabilizer to anterior translation with the arm abducted to 45 (45-90) IGHLC- A&P bands, hammock Primary stabilzer for anterior and inferior instability in abduction Posterior band in flexion/adduction to posterior instability
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Static Restraints Adhesion/cohesion Suction Cup
Attraction of joint fluid to itself and to the articular surface Suction Cup The glenoid and labrum act as a suction cup Negative joint pressure Analogous to pulling on the plunger of a plugged syringe Venting the joint allows 55% increase in anterior translation
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Dynamic Restraints Rotator Cuff Concavity-Compression
Enhances the conformity of the joint and increases the force required to translate Could be more important than ligament restraints RC blend into ligaments and could provide dynamic restraints through them Importance of RC strengthening in Rehab Anterior-superior escape in CTA
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Dynamic Restraints Biceps Deltoid
Difficult to determine its actual contribution Many studies with differing results Most likely is a humeral head depressor Must be flexing or supinating forearm for any shoulder contribution Deltoid Increase activation in unstable shoulder
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Dynamic Stability Scapular Rotators Proprioception
Trapezius, Rhomboids, Lat, Serratus, Levator 2:1 ratio of GH motion to Scapulothroacic motion Provide stable platform beneath humeral head Importance rehab to include scapular rotators Proprioception Mechanoreceptors send message in reflex arc to control shoulder Increased hand position error in pts with MDI Surgery improves GH proprioception
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Breakdown of Stability
Minimal loads: Negative intraarticular pressure Adhesion/Cohesion Suction Cup Moderate loads, Mid-range: Concavity-compression Labrum Scapulothoracic Rhythm & Proprioception Large loads, End-range: IGHL
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Pathoanatomy of Instability: Bankart Lesion
“Essential lesion” Separation of inferior capsulolabral complex from glenoid neck Broca and Hartmann 1890 Perthes 1906 Bankart 1923, 1939
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Bankart Lesion: 1. Disrupts the conacavity compression
2. Eliminates the chock-block 3. Decreases depth by 50% 4. Detaches capsuloligamentous structures 5. May eliminate the negative intraarticular pressure
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Pathoanatomy of Instability: Capsular injury
Bankart Less often considered the all-or-none “Essential lesion” but still the most common lesion: 62-97% Incidence Simulation of Bankart results in only minimal increase in translation Plastic deformity of the capsule is required ALPSA: anterior labral periosteal sleeve avulsion HAGL/BHAGL: humeral avulsion of the glenohumeral ligaments GLAD: glenolabral articular disruption
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Pathoanatomy of Instability:
ALPSA Lesion
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Pathoanatomy of Instability:
HAGL Lesion
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Pathoanatomy of Instability: Bone Loss
Humerus Hill-Sachs or Reverse Hilll-Sachs 80-100% of anterior dislocations 25% of subluxations Larger defects Longer dislocations Recurrent Inferior >30% defect may lead to recurrent instability Tendon Allograft Replacement
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Pathoanatomy of Instability: Bone Loss
Glenoid Bony Bankart Erosion from Recurrent dislocation Defects < 20% repair labrum/capsule Bigliani – loss of > 25% warrants bony reconstruction Burkart – inverted pear glenoid requires bony reconstruction 61% recurrence w/ inverted pear or engaging Hill Sachs 4% recurrence without Measure bare spot to anterior rim. Reconstruction Iliac crest Coracoid (Latarjet)
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Glenoid Greis – Glenoid defect of 30% of the diameter at the anterior inferior quadrant Contact area across entire glenoid decreased 41% Contact pressure increased by almost 100%
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Pathoanatomy of Instability: Associated Injuries
Rotator cuff tear Under 30 rare Over 40 85% Nerve injuries Axillary: up to 33% Musculocutaneous
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Clinical Evaluation Etiology: Traumatic vs. Atraumatic
Direction: Ant vs. post vs. MDI Timing: Acute vs. chronic Frequency: Single vs. recurrent Degree: Sublux vs. Dislocate Volition: Voluntary vs. involuntary
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Clinical Evaluation History PE EUA Arthroscopy Radiographs
Acute vs. Chronic Isolated vs. recurrent Dislocation vs. subluxation Direction Past treatment PE ROM Atrophy Winging Sulcus Load and Shift Apprehension Relocation Release test EUA Arthroscopy Radiographs
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Hill Sachs Evaluation Stryker notch view CT preferred over MRI
Hand to head, elbow up Beam angle up 10 degrees Centered over coracoid CT preferred over MRI MRI underestimates bone defect
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West Point view Prone, 25 degree from midline, directed through axilla
Itoi – correlated West Point view with CT for glenoid bone loss Axillary view underestimates
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Anterior Dislocation 85-95% of dislocations Treatment
Prompt atraumatic reduction Immobilization Risk of Recurrence Age (<30) Activity level Compliance with rehab Contralateral shoulder instability Bony defects
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Emergent Management Closed reduction
Adequate sedation and analgesia needed Analgesic techniques Intravenous Intra-articular lidocaine (Kosnik et al., 1999; Miller et al., 2002) Reduced time and resources Equivalent success
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Emergent Management Hippocratic Counter traction Stimson Milch
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Emergent Management Immobilization (duration)
No change in outcome ? (Hovelius et al., 1983; Rowe et al. 1961) One week (Kazar et al., 1969) Three weeks (Kiviluoto et al., 1980; Stromsoe et al 1980) Dependent on age ? >40 1 week <40 3 weeks
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Emergent Management Immobilization (position)
Internal rotation and adduction (sling) Labrum anatomically better position in ER (Itoi et al, 2001)
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Emergent Management Immobilization (position)
Clinical follow-up for 15 months (Itoi et al., 2003) No recurrent dislocation with ER immobilization 30% dislocation with IR immobilization 0% vs. 45% for patients younger than 30
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Goals of Rehabilitation
Return dynamic stabilizers to functional state Protect healing of static stabilizers Minimal immobilization Early ROM, avoid ER Strengthening in plane of scapula Bracing/harnessing for return to sports
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Success of Rehabilitation
Aronen 1984: 75% in 20 athletes Arciero 1994: 20% in 15 athletes Higher patient expectations Patients are less willing to alter activities
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Anterior dislocation Surgery Early vs. Late Open vs. Arthroscopic
<30 y/o surgery may be first line? Open vs. Arthroscopic Open still “gold standard” Reader beware Some open techniques not anatomic (high OA) Early scopic studies with poor techniques and implants
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Scope vs. Open Arthroscopic Open Minimizes dissection
Decreased damage to soft tissues Subscap Earlier Rehab Better ROM Hard to over tighten Better visulaization Treat other pathology Learning Curve Outpatient Open Gold standard Initially lower recurrence Possibly over constrained Still required for Large bony defects HAGL? Capsular insufficiency Revision Cosmesis OR time Inpatient
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Scopic vs. Open Open (recurrence) Scopic Anchors Bacilla 7% Gartsman 8
Putti-Platt % Mag-Stack Eden-Hybbinette Gallie 2.9 DuTolt & Roux Bristow 1.7 Bankart 3.3 Capsulorrhaphy Classic Bankart Rowe and Bankart 96% success Scopic Anchors Bacilla 7% Gartsman Cole 0 Kim 4 Kim 10 Abrams 6.6 Mazzocca Fabbriciani 0 Recent scopic anchor technique also with 96% success
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Open Capsular Subscap Bony Bankart repair Putti-plat Magnuson-Stack
Bristow Latarjet
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Arthroscopic Lateral decubitus Bump in axilla or Arthrex Star Sleeve
2-3 portals Anchors Knotless? Bioabsorbable? Fiberwire?
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Arthroscopic Bankart EUA Portals Address posterior first
Posterior- more superior and lateral Anterior- leave room for 2 if needed Address posterior first Labrum/capsule Back anteriorly Mobilize labrum Debride surface Place anchor Pass suture through capsule shifting north/south and east/wet Tie- horizontal mattress? Rotator interval if needed
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Posterior Acute posterior Chronic Volitional Recurrent
<5% Unrecognized in 50-80% of patients initially Chronic > 6weeks locked out the back Volitional Recurrent Habitual dislocator (psych issues) Voluntary (can selectively fire muscles) May become involuntary Dysplastic Recurrent Hypoplasia, glenoid or humeral retroversion
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Posterior Treatment Nonop Surgery Results
Rehab focusing on infraspinatus/teres minor/posterior deltoid/scapula 63-68% success Surgery OPEN vs. Scopic Capsulorrhaphy/shift Reverse bankart Bone block Glenoid osteotomy Infraspinatous Capsular tenodesis Results 85-91% success
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MDI Subluxate or dislocate in multiple directions, with concurrent reproduction of symptoms in at least 2 directions, one being inferior Symptoms usually in mid-range of motion (ADL’s) Positive Sulcus with symptoms Pathology Widened Rotator Interval Redundant inferior capsule Collagen abnormality? Mechanoreceptor Abnormal muscle control
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MDI Nonop – Rehab Surgery Results Rockwood 88% success rate
Must prove that they will be compliant Surgery Open or scopic inferior shift Scopic Posterior capsule Anterior capsule Rotator Interval Post-op Cast or brace Results Pollack % Brems 85% Hawkins 60% Savoie 88% Gartsman 94% McIntyre 95%
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Conclusion
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