In The Name of GOD
The Soulder Instability
A. Zarezadeh MD
Pathological anatomy
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No essential pathological lesion is responsible for every recurrent dislocation of the shoulder
Bankart in 1938 reported two types of acute dislocations
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In the first type, the humeral head forced through the weakest capsule in the antero-inferior part of the
shoulder.
In the second type, the humeral head is forced anteriorly and tears the labrum and also the capsule and
periosteum from the anterior neck of the scapula.
This detach met of the glenoid labrum has been called the Bankart lesion.
Most authors agree that Bankart lesion is the most common pathological lesion in recurrent
dislocation of the shoulder.
Pathological anatomy
• Excessive laxity of the capsule also causes the instability of the shoulder
(congenital collagen deficiency)
• A big humeral head impaction fracture at the postero-lateral aspect of the
humeral head, that has been called Hill-Sachs lesion can produce shoulder
instability.
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3D CT is the best method for evaluating the extent of the defect.
Pathological anatomy
• It seems that no single essential lesion is responsible for all recurrent
dislocations of the shoulder.
• No single operative procedure can be applied to every patient.
• The surgeon must search carefully for and identify the deficiencies to
choose proper procedure.
Classification
• Successful treatment of shoulder instability is based on the through
understanding of the pathological lesions and correct classification of the
shoulder instability.
• Classification and treatment are based on:
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The direction, degree and duration of symptoms
The trauma that resulted in instability
The patient’s age, mental set and associated medical conditions (such as: seizures,
neuromuscular disorders, collagen deficiencies and congenital disorders)
Classification
• The direction of instability can be categorized as:
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Unidirectional
Bidirectional
Multidirectional
Classification
• Anterior recurrent dislocation account for about 95%
• Posterior recurrent dislocation account for about 5%
• Inferior and superior dislocations are rare
• Superior instability generally arises secondary to severe R.C. insufficiency.
• About 50% of posterior dislocations can be missed
Classification
• Instability is categorized as:
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Subluxation or dislocation
• The duration of the symptoms should be recorded as:
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Acute
Sub acute
Chronic (when the humeral head has remained dislocated longer than 6 weeks.)
• Recurrent
Age
• Age is an important factor in predicting pathological lesions and outcomes.
• Recurrent rate is more than 90% in patients younger than 20 years old.
• Recurrent rate is about 10% in patients older than 40 years old.
• Associated R.C. tearing is about 30% in patients older than 40 years old.
• R.C. tearing in patients older than 60 years old is approximately 80%.
• Greater tuberosity fx is common in patients older than 40 years old.
• In patients with medical conditions, such as: Primary collagen disorders
(Ehlers-Danlos, Marfan) and neuromuscular disorders conservative
treatment should be the initial approach.
• Matsen’s Classification system is useful for categorizing instability patterns
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TUBS (Traumatic Unidirectional Bankart Surgery)
AMBRII (Atraumatic Multidirectional Bilateral Rehabilitation if surgery is necessary
Inferior capsular shift and Interval closure)
Matsen’s classification system
History
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The history is important in recurrent instability of the shoulder
The amount of initial trauma should be determined.
High-energy traumatic collision sports and motor vehicle accidents are associated with a
risk of bone defect.
The position, in which the dislocation or subluxation occurs, should be asked.
Dislocations that occur during sleep or with the arm in overhead position often are
associated with a glenoid defect that requires surgical treatment.
Dislocations that are reduced by the patient often are subluxations or dislocations with
ligamentous laxity.
History
• The signs and symptoms of any nerve injury should be recorded.
• In recurrent subluxations, the patient complaint is a sensation of the
shoulder sliding in and out of glenoid.
• The patient may complain of having a “dead arm” as a result of axillary
nerve injury or secondary R.C. syndrome.
• Posterior shoulder instability may present as posterior pain or fatigue with
repeated activities.
Physical examination
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In physical examination of an unstable shoulder:
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The patient should be asked, which position creates instability?
What is the direction of shoulder subluxation or dislocation?
Both shoulders should be examined with the normal shoulder used as a reference.
The examination includes:
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Evaluation for any atrophy or asymmetry
Palpation for any tenderness in anterior or posterior capsule RC and AC joint.
Active and passive ROM should be evaluated.
The muscle testing of the deltoid, RC muscles and scapular stabilizers should be done, graded and recorded from 0 to 5.
Physical examination
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The “shift and load” test is done.
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The amount of anterior and posterior translation of the humeral head in the glenoid is
observed.
The sulcus test- is done with the arm 0 degree and 45 degrees of abduction and
should be graded 0 to 3.
The anterior apprehension -is evaluated with the shoulder in 90 degrees of
abduction, elbow in 90 degrees of flexion and then slight external rotation force.
This test is positive in anterior instability.
Physical examination
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Posterior instability of the shoulder can be evaluated with a posterior clunk test.
(90 degrees abduction is brought to a forward flexion and internally rotated position while
posterior stress is applied to the elbow)
The clunk is felt and producing pain and feeling of subluxation in an unstable shoulder.
The shoulder anterior drawer test (The patient in a supine position and extremity in
abduction and external rotation)
The Jobe relocation test can be used for evaluating instability.
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A feeling of subluxation or apprehension indicates anterior instability.
Radiographic evaluation
• Diagnosis of an unstable shoulder often is made by history and physical
examination.
• An unstable shoulder can be documented by radiographs
• The initial radiographic examination is AP and axillary lateral views.
Radiographic evaluation
• If the initial radiographic evaluation is inconclusive
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Special views
Gadolinium enhanced MRI
CT arthrography can be used to show post traumatic changes
Radiographic evaluation
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The most common special views are:
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AP of the shoulder in internal rotation for evaluation of Hill-Sachs
The west point or Rokous view to show calcification of antro-inferior glenoid rim.
Stryker notch view
Standard double-contrast arthrography
CT scan, particularly 3D is the most sensitive test for detecting and measuring bone
deficiency.
Double contrast CT arthrography
MRI is useful in evaluating soft tissue lesions associated with instability.
The End