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
