Keywords:
Musculoskeletal system, Musculoskeletal bone, CT, Education, Education and training, Outcomes, Patterns of Care
Authors:
V. B. Pai, C. Trivedi, A. Kadavkolan, K. Gupta, A. Agrawal, D. Lokhande, B. Pai; Mumbai/IN
DOI:
10.1594/essr2018/P-0158
Background
GENERAL ANATOMY: (Fig. 1)
The glenohumeral joint (GHJ) is the articulation between the glenoid fossa (GF) of the scapula and the head of the humerus (HH).
The GF is shallow,
thus lending an increased range of motion while providing minimal stability.
The GF is lined by a fibrocartilage,
the glenoid labrum,
which to a certain degree,
increases the depth of the fossa.
.
These osseous structures are surrounded by a fibrous network known as the glenohumeral capsule.
Thickenings of the capsule are known as the superior,
middle,
and inferior glenohumeral ligaments,
which play a crucial role in the static stabilization of the GHJ.
The congruent articular surfaces also provide stability through the principle of concavity compression,
which is particularly important during the midrange of glenohumeral movement when the capsular ligaments are lax.
.
A group of muscles,
collectively called the rotator cuff,
surround this capsule and ensure a balanced force,
which is key to the dynamic stabilization of the HH during motion.
To a lesser degree relative to the rotator cuff,
dynamic constraints are also provided by the long head of biceps,
the pectoralis major,
latissimus dorsi,
and periscapular muscles.
.
PATHOPHYSIOLOGY OF ANTERIOR DISLOCATIONS:
Anteroinferior dislocation is commonly encountered in clinical practice,
as compared to its superior or posterior counterparts.
They dislocations occur due to direct trauma or fall on an outstretched hand.
Following a dislocation,
osseo-labral injuries are commonplace.
In a typical setting,
the dislocated HH impinges on the anteroinferior glenoid labrum,
leading to its detachment (labral injury) along with a tear of the anterior scapular periosteum (Bankart’s lesion).
This may be associated with a fracture of the underlying glenoid (Bony Bankart’s lesion).
Simultaneously,
the impaction of the HH,
more precisely its postero-supero-lateral aspect,
against the glenoid leads to a compression fracture called as the Hill-Sachs lesion.
A variety of permutations and combinations of these osseo-labral injuries are known but are beyond the scope of this review.