SPECTRUM OF MRI FINDINGS IN
GLENOHUMERAL INSTABILITY
ABSTRACT ID NO: 50
INTRODUCTION
The shoulder joint is a ball and socket type of joint that has two main
stabilizers:
the rotator cuff muscles (dynamic)
the labral-ligamentous complex (static).
 The primary function of the rotator cuff muscles is to centralize the
humeral head, limiting superior translation during abduction.
 The glenohumeral joint is the most commonly dislocated joint. The normal
glenoid labrum height and width are 3 mm and 4 mm.
 The glenoid labrum is the ring of fibrocartilage that provides attachment to
the glenohumeral ligaments and the capsule at the glenoid rim and deepens
the glenoid fossa. The attachments of the glenohumeral ligaments and the
long head biceps anchor to the labrum are stronger than the attachment of
the labrum to the glenoid rim. Therefore, the glenoid labrum is commonly
torn or avulsed when excessive force is applied to a glenohumeral
ligament or the long head biceps
ANATOMY
LATERAL VIEW OF THE GLENOID FOSSA WITH ITS LIGAMENTS
The glenohumeral ligaments (inferior, middle, and superior)
are thickened bands of the joint capsule that extend from the
inferior and anterior glenoid and glenoid labrum, to the
anatomic neck region of the humerus.
 The inferior glenohumeral
ligament (IGHL) is a
hammock-like structure that
attaches to the inferior
glenoid, glenoid labrum, and
the humeral neck. Thickened
portions of the IGHL
anteriorly and posteriorly are
referred to as the anterior and
posterior bands.
 The middle glenohumeral
ligament (MGHL) varies in
thickness, shares a common
origin with the SGHL & helps
stabilize the shoulder anteriorly
from 0-45 degrees of abduction
and external rotation.
MGHL
 The superior glenohumeral
ligament (SGHL) is the
smallest ligament and acts with
the coracohumeral ligament to
stabilize the glenohumeral joint
It prevents posterior and inferior
translation of the humeral head.
CHL
SGHL
LH –BICEPS
TENDON
GL
DISCUSSION
On MRI the normal labrum demonstrates low signal
intensity on all pulse sequences, due to the lack of mobile
protons in this dense fibrocartilage. On cross sectional
imaging, the normal labrum is most commonly triangular, but
can also be round, cleaved, notched, flat, or absent
 For localization purposes,
the labrum is divided into
six zones includes:
superior, anterosuperior,
anteroinferior, inferior,
posteroinferior, and
posterosuperior.
MRI diagnosis of labral tears is based on abnormalities in the
signal intensity, morphology, and location (displacement) of
the labrum. The labrum may be frayed, crushed, avulsed, or
torn.
 Tears are classified by morphology, displaced or nondisplaced,
and by location. Labral tears can extend into the biceps anchor as
well as the glenohumeral ligaments.
MRI criteria for diagnosing labral tears include :
 Surface irregularity,
 Increased signal within the substance of the labrum that extends
to the labral surface ,
 Fluid or contrast imbibed into the substance of the labrum ,
 Labral avulsions.
Secondary signs of labral tears include paralabral cysts , periosteal
stripping and tearing, labral associated bone injuries .
Anterior Instability
Posterior Instability
 A Bankart lesion is a
tear of the
anterioinferior glenoid
labrum with an
associated tear of the
anterior scapular
periosteum, with or
without associated
fracture of the anterior
inferior glenoid rim
Classic Bankart
lesion
Bony Bankart lesion
 A Perthes lesion is a
variant of the Bankart,
where the anterioinferior
labrum is avulsed from the
glenoid and the scapular
periosteum remains intact
but is stripped medially.
 A HAGL lesion is humeral
avulsion of the glenohumeral
ligament that occurs from
shoulder dislocation, with
avulsion of the inferior
glenohumeral ligament from the
anatomic neck of the humerus.
HAGL
 A BHAGL is a bony HAGL,
that involves a bone fragment.
 Reverse HAGL lesion: In
posterior instability there is
complete avulsion of the
posterior attachment of the
shoulder capsule and the
glenohumeral ligament from the
posterior humeral neck
Reverse HAGL lesion
GLAD
 The GLAD lesion refers to
glenolabral articular
disruption, which involves
a tear of the anterior
inferior labrum with an
associated glenoid
chondral defect
GAGL
 Glenoid avulsion of the
glenohumeral ligaments
(GAGL) implies an
avulsion of the IGHL from
the inferior pole of the
glenoid, without an
associated inferior labral
disruption
AVUL OF IGHL
ALPSA
 The ALPSA lesion is
characterized by a torn
anteroinferior labrum with an
intact but stripped periosteum
and medial displacement of
the labrum and inferior
glenohumeral ligament
 Inferior ALPSA or cul-de-sac
lesion is medial displacement
of both the anterior-inferior
labrum and the IGHL under
the inferior neck of the
glenoid
TORN ANTR INF
LABRUM
IGHL
Inferior ALPSA
AIL
IGHL
Hill-Sachs lesion
 Hill-Sachs lesion consists of
bony injury to the
posterosuperior humeral
head as a result of inferior
displacement (which occurred
when the humeral head struck the
anterior inferior glenoid during
anterior dislocation).
 Reverse Hill-Sachs lesion
consists of an anteromedial
superior humeral head
impaction fracture
 Bennett lesion is an extra-
articular crescentic posterior
ossification associated with
posterior labral injury and
capsular avulsion
Reverse Hill-Sachs lesion
Bennett
lesion
 Rotator cuff interval
Rotator cuff interval tear
tear do not appear as
complete disruption of the
fibers of its components but
as thinning, irregularity, or
focal discontinuity of the
rotator interval capsule.
 Posterosuperior labral tear
in association with a
paralabral cyst may be
seen in patients with
posterior instability
Paralabral cyst
The SLAP lesion is an injury involving the superior aspect of the
glenoid labrum, which includes the biceps tendon anchor.
SLAP CLASSIFICATION
Type II
Type IV
BHL with extension into biceps tendon
TYPE VII
SLAP CLASSIFICATION
TYPE V
SLAP lesion with
anteroinferior
extension
Superior labral
tear with
MGHL
extension
TYPE IX
Fraying of MGHL
global labral
abnormality
CONCLUSION
 Anterior instability is the most common type of shoulder instability.
 It is associated with a Bankart lesion and its variants and abnormalities of
the anterior band of the inferior glenohumeral ligament, whereas
posterior instability is associated with reverse Bankart and reverse HillSachs lesions.
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