A) PULSE SEQUENCES
1.
Patient supine with the affected arm by the side of the body,
elbow extension,
and forearm in supination.
2.
Surface coils.
3.
Matrix: 256 x 192 or 256 x 256.
4.
Fov: 12- 14 cm.
5.
Axial: slice thickness 4 mm Fig. 1 .
6.
Coronal and sagittal: slice thickness 3 mm Fig. 1 .
7.
A 20 degrees posterior oblique coronal plane in relation to the
humeral shaft with the elbow extended or a coronal plane aligned
with the humeral shaft with the elbow slightly flexed
(20-30 degrees of flexion) Fig. 2 .
8.
MR arthography: axial,
coronal and sagittal FS T1 FSE,
and Coronal FS T2 FSE or STIR.
B) NORMAL ANATOMY
a) Collateral Ligements Complex Fig. 3 :
b) Collateral Lateral Ligament Complex
· Lateral ulnar collateral ligament (LUCL) Fig. 4 .
o LUCL wraps around the posterior aspect of the radial neck.
o Origin: Lateral epicondyle (indistinguishable origin of RCL).
o Insertion: Supinator crest of the ulna.
· Radial collateral ligament (RCL) Fig. 5 .
o Origin: Lateral epicondyle (indistinguishable origin of LUCL).
o Insertion: Anterolateral aspect of the anular ligament.
· Annular ligament (AL) Fig. 6 .
o AL encircles the periphery of the radial head).
o Origin: Anterior margin of the semilunar notch.
o Insertion: Supinator crest of the ulna.
· Accessory collateral ligament.
c) Collateral Medial Ligament Complex
· Anterior bundle (A-MCL) Fig. 7 .
o The A-MCL is the main stabilizer against valgus and internal
rotation stress.
o Origin: The undersurface of the medial epicondyle.
o Insertion: Sublime tubercle of the ulna.
· Posterior bundle (P-MCL) Fig. 8 .
o The P-MCL is the floor of the cubital tunnel.
o Origin: Posterior aspect of the medial epicondyle.
o Insertion: Medial aspect of the olecranon process.
o During elbow flexion the arcuate ligament tenses and
P-MCL relaxes.
o 40% of throwing athletes with medial instability
have ulnar neuropathy.
· Transverse ligament (T-MCL).
C) LATERAL COLLATERAL COMPLEX INJURY
1.
The collateral lateral ligement compplex resist excesive varus and external rotacional stress.
2.
LUCL is the most important in terms of stability.
3.
Tears can involve one or more of the three bundles.
4.
LUCL tears usually involve the humeral origin.
5.
Pathology:
· A fall on an outstretched hand.
· Iatrogenic injury during release or repair of lateral epicondylitis.
· Advanced cases of tennis elbow.
6.
Characteristic bone bruises:
· Posterior capitellum.
· Radial head.
7.
Failure to recognize radial collateral complex tears prior to surgical treatment of tennis elbow will lead to persistent postoperative symptoms.
a) Posterior Dislocation Injury and Instability
Posterolateral rotary instability (PLRI) is the most common pattern of recurrent elbow instability Fig. 9,
Fig. 10,
Fig. 11 ,
Fig. 12 ,
Fig. 13,
Fig. 14 .
Stage 1 Fig. 15 .
· Posterolateral subluxation of the ulna on the humerus.
· Insufficiency or tearing of LUCL.
Stage 2 Fig. 16 .
· The elbow dislocates incompletely.
· Tearing of LUCL and RCL.
· Anterior and posterior capsule are disrupted.
Stage 3
· The elbow dislocates completely.
· Tearing of LUCL,
RCL and articular capsule.
· The A-MCL is intact (Stage 3A) .
· The A-MCL is disrupted (Stage 3B) Fig. 17 ,
Fig. 18.
· Entire distal humerus is stripped of soft tissues (Stage 3C).
b) Posterior Dislocation and Chronic Annular Ligament Injury
Fig. 19 .
· Recurrent painful click.
· Differential diagnosis Fig. 20 :
1 Intraarticular bodies.
2 Posterolateral plica.
3 Ulnar nerve subluxation.
4 Snapping tríceps.
· Pathology:
o Adult injury: Varus elbow stress,
elbow dislocation,
PLRI.
o Children: Nursemaid´s elbow.
D) MEDIAL COLLATERAL COMPLEX INJURY:
1.
Medial joint stability to valgus stress.
2.
Anterior bundle is the main static stabilizer.
3.
Injury mechanism:
1.
Chronic microtrauma from repetitive valgus stress (overhead
throwing sports).
• Medial elbow tension overload,
lateral compression and
extension overload.
• Baseball,
football,
javelin throwing,
voleyball,
golf,
polo.
• Medial elbow pain and valgus instability.
2.
After a fall on an outstretched hand.
4.
Strain of the flexor digitorum superficialis frequently accompanies
an MCL injury.
5.
MRI acute tear: Hyperintensity,
discontinuity,
and soft tissue edema.
6.
MRI chronic tear: Thickening,
abnormally signal,
and discontinuity.
7.
Lateral compartment bone bruises suggest MCL disruption.
a) Acute Anterior Bundle of Medial Collateral Ligament Complex:
· Case 1: A 23-year-old man with pain and medial instability after a
fall on the outstretched arm Fig. 21 .
. Case 2: A 32-year-old man with pain and medial instability
after a fall on the oustretched arm Fig. 22
b) Acute Posterior Bundle of the Medial Collateral
Ligament Complex:
· Case 3: A 25-year-old man with pain and medial instability after
a fall on an outstretched hand Fig. 23 .
c) Avulsion Fracture of the Medial Epicondyle:
· Case 4: A 45-year-old woman with pain,
muscle weakness
and paresthesias after a fall on an outstretched hand Fig. 24 .
d) Repeated Valgus Stress.
Overhead Athlete Fig. 25, Fig. 26 ,
Fig. 27,
Fig. 28 .
e) Chronic A-MCL Injury often is associated with valgus
extension overhead or posteromedial impingement (valgus stress
during throwing).
o Case 5: A 35-year-old voleyball player with chronic elbow pain and
medial instability. Fig. 29 .
o Case 6: A 40-year-old golf player with medial elbow pain
and valgus instability. Fig. 30 .
f) Little Leaguer´s Elbow ( medial epicondyle apohysitis) Fig. 31 :
o Chronic stress injure medial epicondylar physis from repetitive traction
on the apophysis by the common flexor tendon and MCL
(valgus stress during throwing).
o Significant elbow injures may occur in the absence of joint effusion
in clildren.
o Although the ulnar collateral ligament may be sprained with
valgus injures,
it may normally show increased SI on fluid sensitive
sequences in children due to increased elastin content in the
anterior fibers compared with adults.