June 20, 2024

Shoulder Instability is important in early diagnosis and treatment. So here we discuss the different views to diagnose different pathology regarding unstable shoulder.

IMAGING STUDIES on Shoulder Instability

GLENOHUMERAL INSTABILITY

Roentgenographic Findings:

Anterior Posterior view

Grashey View

Axillary view

West Point view

Scapular Y view

Stryker Notch View

Anterior Posterior view:

True AP

Can be taken in neutral, Internal Rotation, and External Position

The beam is centered in the coracoid process with the scapular blade parallel to the film

AP in external rotation

AP view with Internal Rotation  HILL-SACHS LESION

Round humeral head, smooth posterior contour,
Fat along the sub acromial and subdeltoid bursa is seen as a lucent cresent.
Fracture most frequently occurs in the
posterolateral aspect of the humeral head at the junction with the neck, producing a “hatchet” defect called the Hill-Sachs lesion; it is best demonstrated on the anteroposterior projection of the shoulder with the arm internally rotated

Grashey View:

True AP view in the line of the scapula

35 to 40 degrees rotating to the affected side

Better evaluation for Glenn humeral cartilage space, joint congruity, and gleno- humeral subluxation

Axillary View:

An excellent method for evaluation of glenohumeral subluxation/dislocation and osseous bankart lesion.

 Arm abducted to 90 degrees, the beam is tilted 5-10 degrees towards the spine

West Point View:

•Anterio- Inferior Glenoid rim is better visualized

•Osseous Bankart lesion is better visualized

Scapular Y-View

the patient is erect, with the injured side against the radiographic table.

The patient’s trunk is rotated approximately 20 degrees from the table to allow for the separation of the two shoulders (inset).

 The arm on the injured side is slightly abducted and the elbow flexed, with the hand resting on the ipsilateral hip.

 The central beam is directed toward the medial border of the protruding scapula. (This view may also be obtained with the patient lying prone on the radiographic table and the uninjured arm elevated approximately 45 degrees.)

The Y-shaped intersection between the scapular body, acromion process, and coracoid process and access fracture.

The humeral head can be centered on the transaction point

True lateral view of scapula/ oblique view of the humerus

Stryker Notch View:

Better visualization of the posterolateral aspect of the humeral head

 Excellent for depleting a Hill Sachs deformity or flatting of the humeral head.

Anterior Dislocation of Shoulder Joint

HILL SACHS LESION

Bankart Lesion

Posterior Dislocation of Shoulder

AP radiographs may appear nearly normal in patients with posterior dislocation.

The additional axillary view gives 100% diagnosis.

Inferior Shoulder Dislocation

An arm is abducted and cannot be lowered down

An inferior dislocation can mimic a subcategory of glenohumeral dislocation known as subglenoid anterior dislocation, where the humeral head rests directly inferior to the glenoid in the AP and lateral projections 4. It is distinguished from the latter by the humeral shaft’s position parallel to the scapular spine.

CT SCAN/CT Arthrography on Shoulder Instability

Excellent modality to define osseous details

3D CT is best for quantification of bone loss

Superior to MRI in documenting the glenoid bone loss and bony bankart lesion

Limitations:

Exposure to ionizing radiation

Poor specificity to labrum lesion

MRI

Superior in visualization of soft tissues

Better visualization for labrum lesion and capsuloligamentous pathology

Also demonstrate:

Rotator cuff tears

Labrum morphology

Increase joint volume

Chondral lesions

GT fractures / edemas

MR Arthrography increases sensitivity and specificity for diagnosing instability and cuff lesion.

Recently MRA is done in the ABER position: to detect undisplaced tears

Used to access elongation of the capsule with chronic anterior instability, multidirectional instability and posterior instability.

Detects:

Perthes lesion

Anterior labrum periosteal sleeve avulsion(ALPSA)

Glenoid Labrum Articular Defects(GLAD)

Humeral Avulsion of Glenohumeral Ligaments (HAGL)

BANKART LESION

OSSEOUS BANKART LESION

PERTHES LESION

HILL SACHS LESION

ALPSA

GLAD

HAGL