Sports Medicine: Just the Facts

CHAPTER 43 • MAGNETIC RESONANCE IMAGING: TECHNICAL CONSIDERATIONS AND UPPER EXTREMITY 259

communicate with the cyst (Tung et al, 2000).

Unenhanced fast spin echo imaging can clearly not

only demonstrate paralabral cysts but also their com-

munication with the labrum (Fig. 43-3).

• The fibrocartilaginous glenoid labrum helps to deepen
  the glenoid and maintain glenohumeral joint stability.
  The glenoid labrum is normally seen as a smooth uni-
  form triangular hypointense focus adherent to the
  osseous glenoid on all pulse sequences. Tears of the

glenoid labrum can be diagnosed as abnormal irregu-

lar high signal coursing through the substance of the

labrum, with associated abnormal labral morphology.

Detached fragments of the glenoid can also be seen.

• In addition to the glenoid labrum and capsule, three
  glenohumeral ligaments help to maintain stability of
  the shoulder. These are the superior, middle, and infe-
  rior glenohumeral ligaments.


• The diagnosis of adhesive capsulitis, usually diag-
  nosed clinically and often confirmed with conven-
  tional arthrography, can be suggested at MR imaging,
  with thickening and occasionally hyperintensity of the
  joint capsule, preferential fluid distention of the
  biceps tendon sheath, absence of conspicuous fluid in
  the glenohumeral joint and scarring in the rotator
  interval.


• The rotator interval is the anatomic space bordered by
  the subscapularis and supraspinatus tendons containing
  the coracohumeral and superior glenohumeral liga-
  ments (Ho, 1999; Potter, 2000). Rotator interval
  injuries and lesions can be associated with gleno-
  humeral joint instability (Ferrari, 1990; Harryman et al,
  1992).
  •Various named labral injury patterns exist. These
  include the superior labrum anterior and posterior
  (SLAP) lesion (Snyder et al, 1990), the anterior
  labral ligamentous periosteal sleeve avulsion
  (ALPSA) lesion (Neviaser, 1993), and the humeral
  avulsion of the glenohumeral ligament(HAGL) lesion
  (Bui-Mansfield et al, 2002).


• SLAP lesions are generally classified into four types,
  all of which can be diagnosed on high-resolution non-
  contrast MR imaging; however, some authors have
  found the use of intra-articular gadolinium helpful
  (Jee et al, 2001).
  •Type I: Fraying and degeneration of the superior
  labrum (inhomogeneous and hyperintense on MR
  without detachment)
  •Type II: Stripping of the superior labrum and biceps
  anchor from the glenoid
  •Type III: A bucket-handle type tear of the superior
  labrum with an intact biceps
  •Type IV: Bucket handle type tear of the superior
  labrum with involvement of the biceps anchor (Snyder
  et al, 1990)


• The glenohumeral joint is the most prone to dislocate
  all the joints in the body. Types of glenohumeral joint
  dislocations include subcoracoid, subglenoid, sub-
  clavicular, and intrathoracic.


• Injuries to the acromioclavicular(AC) joint can be
  evaluated with MR imaging, with detailed depiction
  of the AC joint capsule and well as the supporting lig-
  amentous structures, such as the coracoclavicular lig-
  ament.

FIG 43-1(b) Oblique coronal fast spin echo image of the same
shoulder at a slightly more posterior level demonstrates a linear
chondral fragment in the axillary recess (arrow).

FIG 43-2 Axial fast spin echo image of the shoulder demon-
strates the sequela of an anterior dislocation. Focal contour
abnormality at the posterior aspect of the humeral head is a Hill
Sachs impaction fracture (thick white arrow). There is, in addi-
tion, a Bankart lesion (anteroinferior labral tear) (thin white
arrow).