In The Name of GOD

The Soulder Instability

A. Zarezadeh MD

Pathological anatomy

• No essential pathological lesion is responsible for every recurrent dislocation of the shoulder

• Bankart in 1938 reported two types of acute dislocations• 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.

• 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:

• 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:

• 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:

• Subluxation or dislocation

• The duration of the symptoms should be recorded as:

• 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

• 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

• 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

• In physical examination of an unstable shoulder:

• 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:

• 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

• The “shift and load” test is done.

• 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

• 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.

• 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

• Special views

• Gadolinium enhanced MRI

• CT arthrography can be used to show post traumatic changes

Radiographic evaluation

• The most common special views are:• 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