AJR 2000; 175:667-672
© American Roentgen Ray Society
MR Arthrography of the Labral Capsular Ligamentous Complex in the Shoulder
Imaging Variations and Pitfalls
Yang Hee Park1,
Ji Yeon Lee2,
Sung Hee Moon1,
Jong Hyun Mo1,
Bo Kyu Yang3,
Sung Ho Hahn3 and
Donald Resnick4
1
Department of Radiology, National Police Hospital, 58 Karakbon-dong,
Songpa-gu, Seoul, 138-169, Korea.
2
Department of Radiology, Samsung Medical Center, 50 Irwon-dong, Kangnam-gu,
Seoul, 135-710, Korea.
3
Department of Orthopedic Surgery, National Police Hospital, Songpa-gu, Seoul,
138-169, Korea.
4
Department of Radiology, University of California at San Diego Medical Center,
200 W. Arbor Dr., San Diego, CA 92103.
Received December 13, 1999;
accepted after revision February 16, 2000.
Presented at the annual meeting of the American Roentgen Ray Society, New
Orleans, May 1999.
Address correspondence to Y. H. Park.
Abstract
OBJECTIVE. Using MR arthrography, we examined normal anatomy,
anatomic variations, and pitfalls of imaging the labral capsular ligamentous
complex in the asymptomatic shoulder.
SUBJECTS AND METHODS. We obtained 108 MR arthrograms of the
glenohumeral joint in 95 asymptomatic volunteers with axial (108 shoulders)
and oblique coronal (56 shoulders) images. We examined labral shape, patterns
of capsular insertion, presence or absence of glenohumeral ligaments, and
pitfalls of imaging. Our patients were men (auxiliary policemen) between 19
and 24 years old (mean age, 21 years).
RESULTS. The shapes of labra were triangular (anterior part, 64%;
posterior part, 47%), round (17%; 33%), flat (2%; 17%), cleaved (11%; 1%),
notched (3%; 0%), or absent (2%; 2%). Using the system of Mosely and
Overgaard, the anterior capsular insertion was type 1 in 63% of shoulders,
type 2 in 20%, and type 3 in 17%; the posterior capsular insertion was type 1
in 60% of shoulders, type 2 in 31%, and type 3 in 9%. The superior and
inferior glenohumeral ligaments were present in 99% of shoulders, but the
middle glenohumeral ligament was present in only 79%. We also detected many
pitfalls of MR imaging in identifying findings such as the undercutting of the
labrum by cartilage (32% of shoulders), prominent axillary folds (46%),
sublabral holes (7%) or recesses (33%), Buford complexes (2%), and sulci
between the biceps tendon and superior labrum (30%).
CONCLUSION. Knowledge of normal anatomy and anatomic variations of
the labral complex is important for the examination of the shoulder with MR
arthrography.
Introduction
Shoulder instability is a common condition that primarily affects young
active people, especially athletes. To correctly diagnosis and properly treat
shoulder instability, many methods have been used such as routine radiography,
conventional arthrotomography, CT arthrography, and MR imaging
[1,2,3,4].
MR arthrography is also an important imaging technique for assessing the
labral capsular ligamentous complex of the shoulder joint
[5,6,7].
The labral capsular ligamentous complex is an important component of shoulder
stability [8,
9]. Many normal variations of
this complex that are seen on MR imaging and that are confused with pathologic
abnormalities have been reported in the literature, but their appearance on MR
arthrography has received little attention
[10,11,12,13].
We performed MR arthrography in asymptomatic shoulders to evaluate the
appearance and frequency of anatomic variations and imaging pitfalls.
Subjects and Methods
We obtained 108 MR arthrograms of the glenohumeral joint in 95 asymptomatic
volunteers with axial (108 shoulders) and oblique coronal (56 shoulders)
images. Our patients were men (auxiliary policemen) between 19 and 24 years
old (mean age, 21 years). Fifty right shoulders and 58 left shoulders were
examined.
MR arthrography was performed with fluoroscopic guidance, and
intraarticular positioning of the needle was confirmed with a small amount of
iodinated contrast material (Ultravist 370; Schering, Berlin, Germany).
Subsequently, 15-20 mL of a mixed solution was injected, which was composed of
250 mL of saline, 0.1 mmol of gadolinium diethylene triamine pentaacetic acid
(Magnevist; Schering), and 0.3 mL of epinephrine (1:1000). A 0.5-T MR scanner
(Gyroscan; Philips, Ienthoven, The Netherlands) was used, and T1-weighted
spin-echo axial images (TR range/TE range, 450-500/21-26), often supplemented
with oblique coronal images, were obtained. The thickness and interval of the
slices were 3.0 mm and 0.3 mm, respectively. During MR imaging, the volunteer
was lying in the supine position with the arm in a neutral position. All MR
arthrographic images were independently interpreted by three radiologists who
were experienced in musculoskeletal MR imaging. Discrepancies among observers
were resolved by consensus. The shape of the anterior and posterior parts of
the labrum was evaluated, and descriptive terms such as triangular, round,
flat, cleaved, notched, and absent were applied
[11] (Fig.
1A,1B,1C,1D,1E,1F).
At the inferior level of the glenoid cavity, the anterior and posterior areas
of the capsular insertion were classified into one of three categories
according to the system of Mosely and Overgaard
[14]: type 1 was a capsular
insertion on the labrum, type 2 was an insertion occurring at the junction of
the labrum and the glenoid, and type 3 was an insertion more medial to this
junction on the cortical surface of the glenoid neck. The presence or absence
of glenohumeral ligaments and additional findings such as the undercutting of
the labrum by cartilage, sublabral holes, sublabral recesses, or Buford
complexes (the combination of the absence of the anterior superior labrum and
the presence of a cordlike middle glenohumeral ligament)
[15] were noted. We also
determined the presence or absence of a prominent axillary fold (simulating an
intraarticular body) and any sulci between the biceps tendon and superior
labrum on oblique coronal images.
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Fig. 1A. —Labral shapes. Drawings show triangular labrum, anteriorly and
posteriorly (A); round labrum, anteriorly and posteriorly (B);
cleaved labrum, anteriorly (C); notched labrum, anteriorly (D);
notch extends in labrum in more vertical fashion than horizontally oriented
cleft; flat labrum, anteriorly and posteriorly (E); and absent labrum,
anteriorly and posteriorly (F). Note glenoid rim has no visible
labrum.
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Fig. 1B. —Labral shapes. Drawings show triangular labrum, anteriorly and
posteriorly (A); round labrum, anteriorly and posteriorly (B);
cleaved labrum, anteriorly (C); notched labrum, anteriorly (D);
notch extends in labrum in more vertical fashion than horizontally oriented
cleft; flat labrum, anteriorly and posteriorly (E); and absent labrum,
anteriorly and posteriorly (F). Note glenoid rim has no visible
labrum.
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Fig. 1C. —Labral shapes. Drawings show triangular labrum, anteriorly and
posteriorly (A); round labrum, anteriorly and posteriorly (B);
cleaved labrum, anteriorly (C); notched labrum, anteriorly (D);
notch extends in labrum in more vertical fashion than horizontally oriented
cleft; flat labrum, anteriorly and posteriorly (E); and absent labrum,
anteriorly and posteriorly (F). Note glenoid rim has no visible
labrum.
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Fig. 1D. —Labral shapes. Drawings show triangular labrum, anteriorly and
posteriorly (A); round labrum, anteriorly and posteriorly (B);
cleaved labrum, anteriorly (C); notched labrum, anteriorly (D);
notch extends in labrum in more vertical fashion than horizontally oriented
cleft; flat labrum, anteriorly and posteriorly (E); and absent labrum,
anteriorly and posteriorly (F). Note glenoid rim has no visible
labrum.
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Fig. 1E. —Labral shapes. Drawings show triangular labrum, anteriorly and
posteriorly (A); round labrum, anteriorly and posteriorly (B);
cleaved labrum, anteriorly (C); notched labrum, anteriorly (D);
notch extends in labrum in more vertical fashion than horizontally oriented
cleft; flat labrum, anteriorly and posteriorly (E); and absent labrum,
anteriorly and posteriorly (F). Note glenoid rim has no visible
labrum.
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Fig. 1F. —Labral shapes. Drawings show triangular labrum, anteriorly and
posteriorly (A); round labrum, anteriorly and posteriorly (B);
cleaved labrum, anteriorly (C); notched labrum, anteriorly (D);
notch extends in labrum in more vertical fashion than horizontally oriented
cleft; flat labrum, anteriorly and posteriorly (E); and absent labrum,
anteriorly and posteriorly (F). Note glenoid rim has no visible
labrum.
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Results
The morphology of the anterior and posterior parts of glenoid labrum was
considerably variable, with several common dominant features
(Table 1). The most common
shape was triangular, found anteriorly in 64% of shoulders and posteriorly in
47% (Fig. 2A). The second most
common shape was round, found anteriorly in 17% of shoulders and posteriorly
in 33% (Fig. 2B). The flat
labrum was found in anteriorly 2% of shoulders and posteriorly in 17%
(Fig. 2B). The cleaved and
notched shapes were noted anteriorly in 11% and 3% of shoulders, respectively
(Figs. 2C and
2D), especially at the
superior and middle levels. Labral absence was revealed anteriorly in 2% of
shoulders and posteriorly in 2% (Fig.
2E).
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Fig. 2A. —Glenoid labral shape of various patients on T1-weighted axial MR
arthrography. MR arthrograms show triangular variation, anteriorly and
posteriorly (A; note middle glenohumeral ligament [arrow]);
round variation, anteriorly and flat, posteriorly (B); cleaved
variation, anteriorly (arrow, C); notched variation,
anteriorly (arrow, D); and absent variation, anteriorly
(E).
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Fig. 2B. —Glenoid labral shape of various patients on T1-weighted axial MR
arthrography. MR arthrograms show triangular variation, anteriorly and
posteriorly (A; note middle glenohumeral ligament [arrow]);
round variation, anteriorly and flat, posteriorly (B); cleaved
variation, anteriorly (arrow, C); notched variation,
anteriorly (arrow, D); and absent variation, anteriorly
(E).
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Fig. 2C. —Glenoid labral shape of various patients on T1-weighted axial MR
arthrography. MR arthrograms show triangular variation, anteriorly and
posteriorly (A; note middle glenohumeral ligament [arrow]);
round variation, anteriorly and flat, posteriorly (B); cleaved
variation, anteriorly (arrow, C); notched variation,
anteriorly (arrow, D); and absent variation, anteriorly
(E).
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Fig. 2D. —Glenoid labral shape of various patients on T1-weighted axial MR
arthrography. MR arthrograms show triangular variation, anteriorly and
posteriorly (A; note middle glenohumeral ligament [arrow]);
round variation, anteriorly and flat, posteriorly (B); cleaved
variation, anteriorly (arrow, C); notched variation,
anteriorly (arrow, D); and absent variation, anteriorly
(E).
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Fig. 2E. —Glenoid labral shape of various patients on T1-weighted axial MR
arthrography. MR arthrograms show triangular variation, anteriorly and
posteriorly (A; note middle glenohumeral ligament [arrow]);
round variation, anteriorly and flat, posteriorly (B); cleaved
variation, anteriorly (arrow, C); notched variation,
anteriorly (arrow, D); and absent variation, anteriorly
(E).
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Capsular insertion was considerably variable at the inferior glenoid level,
with a type 1 capsule present anteriorly in 63% of shoulders, type 2 in 20%,
and type 3 in 17%. The posterior capsular insertion was type 1 in 60% of
shoulders, type 2 in 31%, and type 3 in 9% (Figs.
3A and
3B). The superior and inferior
glenohumeral ligaments were present in all cases except one (99%), but the
presence of the middle glenohumeral ligament was not constant (present in 79%
of cases) (Fig. 4).
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Fig. 3A. —Three types of capsular insertion on T1-weighted MR arthrography. MR
arthrogram shows type 1 (insertion on labrum, solid arrow) in
posterior capsular insertion and type 3 (insertion more medial to junction of
labrum and glenoid, open arrow) in anterior capsular insertion in
21-year-old man.
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Fig. 3B. —Three types of capsular insertion on T1-weighted MR arthrography. MR
arthrogram shows type 2 (insertion at junction of labrum and glenoid,
solid arrow) in posterior capsular insertion and type 3 (open
arrow) in anterior capsular insertion in 19-year-old man.
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Fig. 4. —21-year-old man with back pain. T1-weighted axial MR arthrogram
fails to show middle glenohumeral ligament at superomedial level of
glenohumeral joint, indicating absence of ligament. Note tendon of
subscapularis muscle (arrow).
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We noted many appearances resembling labral defects, such as the
undercutting of the labrum by hyaline cartilage (32% of shoulders)
(Fig. 5A), sublabral holes
(7%) (Figs. 5B and
5C) or recesses (33%)
(Fig. 5D), and Buford
complexes (2%) (Fig. 5E). Prominent axillary folds mimicked intraarticular bodies (46%)
(Fig. 5F), and a sulcus was
seen between the biceps tendon and superior labrum (30% of shoulders) (Figs.
5C and
5G).
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Fig. 5B. —T1-weighted MR arthrograms show findings resembling labral tears.
Sublabral hole (arrow) is noted in anterosuperior portion of glenoid
(high-signal-intensity effusion is interposed in this foramen).
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Fig. 5C. —T1-weighted MR arthrograms show findings resembling labral tears.
Oblique coronal view of same patient as in B shows "double Oreo
cookie configuration" with black (glenoid cortex, open arrow),
white (sublabral hole, solid arrow), black (labrum,
arrowhead), white (sulcus, open arrowhead), and black
(biceps tendon, white arrow) areas, which are not superior labrum
anteroposterior lesions.
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Fig. 5E. —T1-weighted MR arthrograms show findings resembling labral tears.
Middle glenohumeral ligament (arrow) is thick and cordlike with
absence of anterosuperior labrum, indicating Buford complex.
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Fig. 5G. —T1-weighted MR arthrograms show findings resembling labral tears.
Oblique coronal MR arthrogram shows small sulcus (solid arrow)
between superior labrum (arrowhead) and biceps tendon (open
arrow).
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Discussion
Several imaging methods have been used to evaluate the glenoid labrum,
ligaments, and joint capsule. Although MR imaging has been used in the
examination of the glenoid labrum, there are some difficulties with the
technique [13,
16]. Hajek et al.
[17] were the first to perform
MR arthrography with the injection of a mixture of saline solution and
gadopentetate dimeglumine into the joint space; they found that many anatomic
structures were better delineated because of capsular distention. The origin
and course of the glenohumeral ligaments, tears of the glenoid labrum, and
relationship of the labrum with the bicipital tendon and glenohumeral
ligaments are better revealed on MR arthrography than on conventional MR
imaging [5,
12]. It is essential to
understand the normal anatomy and anatomic variations of the labral capsular
ligamentous complex for the accurate interpretation of MR arthrograms in
patients with clinically suspected shoulder instability.
The glenoid labrum is composed of fibrocartilaginous tissue that has low
signal intensity on T1- and T2-weighted MR images. The labrum deepens the
glenoid cavity, from which the bicipital tendon and glenohumeral ligament
originate. The size and shape of the glenoid labrum in asymptomatic subjects
are variable. Neumann et al.
[11] reported that the most
common labral shape was triangular (anterior part, 45%; posterior part, 73%),
and the next most frequent appearance was round (19%; 12%). We found that, in
the anterior part of the labrum, a round shape increased in frequency at
inferior levels, and cleaved or notched shapes increased in frequency at the
superior and middle levels, results comparable with those of Neumann et al.
Liou et al. [10] suggested
that the apparent cleft in the labrum was actually caused by the orgin of the
inferior glenohumeral ligament at this location. In our study, in Figures
2C and
2D, we followed the clefts and
notches inferiorly; however, we noted no relationship between the cleft and
the orgin of the inferior glenohumeral ligament. Round and flat labra were
more common posteriorly than anteriorly, unlike the results of Neumann et al.
This discrepancy may be explained by capsular distention related to the
intraarticular injection of contrast material.
The attachment of the anterior part of the inferior capsule was most
commonly type 1 (63% of shoulders), a finding that is comparable with that of
a previous report [11]. In the
posterior part of the capsule, type 1 (60%) and type 2 (31%) capsular
attachments were commonly seen, findings that differ from those of Neumann et
al. [11], who found type 1 in
100% of shoulders and type 2 in 0%. Types 2 and 3 insertions might be more
commonly observed because of the capsular expansion seen on MR arthrography.
The capsular attachments observed by Mosely and Overgaard
[14] were at the level of the
insertion site of the middle glenohumeral ligament. We observed the capsular
attachment at the inferior level of the glenoid, but our results may have a
considerable validity to verify the tendency of the capsular attachment.
The glenohumeral ligaments are important for the stability of the shoulder
joint [18]. The middle
glenohumeral ligament may originate from the labrum or neck of the glenoid
fossa and course posterior to the subscapularis tendon. The middle
glenohumeral ligament is an important stabilizing structure at 40° of
abduction and external rotation of the humerus
[5,
12]. The middle glenohumeral
ligament is most variable in size and frequency and may be attenuated or
absent in up to 30% of normal shoulders
[12].
One pitfall of MR imaging is that findings may mimic lesions suggestive of
glenohumeral instability. In the superior portion of the labrum, a sublabral
hole and recess have been recognized by other investigators
[9,
19]. Cooper et al.
[9] reported that the labrum
was loosely attached by thin capsular tissue (sublabral recess) in five
specimens and was not attached to the glenoid rim at all (sublabral hole) in
four specimens among 23 newly frozen shoulders. De Palma et al.
[19] reported that the
superior labrum in fetuses and infants was firmly attached to the hyaline
cartilage without evidence of a sublabral foramen, and alterations were seen
in the superior labrum by the second decade of life. They concluded that the
detachment of the superior labrum was an age-dependant degenerative phenomenon
because its prevalence increased with the subject's age. In that study,
nonattachment of the superior labrum was noted in only 17% of specimens from
subjects in the second decade of life, more than 50% of subjects older than 20
years, and more than 95% of subjects in the seventh and eight decades of life.
In our study, a sublabral hole was revealed in 7% of subjects, and a sublabral
recess was revealed in 33% of subjects, findings probably related to the young
age of our volunteers. In 30% of subjects imaged in the oblique coronal view
(56 shoulders), a sulcus was revealed between the superior labrum and the
biceps tendon. In some cases, a sublabral hole and a sulcus between the
superior labrum and biceps tendon were revealed simultaneously (Figs.
5C and
6A,6B),
a finding called the "double Oreo cookie configuration." In our
volunteers, this configuration was different from the description of Smith et
al. [20]. They described
glenoid cortex (black), sublabral recess (white), labrum (black), superior
labrum anteroposterior tear (white), and labrum (black) as the double Oreo
cookie configuration.
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Fig. 6A. —Sublabral hole and sulcus between labrum and biceps tendon. Drawing
shows glenolabral junction with normal sublabral hole (solid arrow)
and sulcus (double arrow) between labrum (arrowhead) and
biceps tendon (open arrow).
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Fig. 6B. —Sublabral hole and sulcus between labrum and biceps tendon. Drawing
shows "double Oreo cookie configuration" with black (glenoid
cortex), white (fluid in sublabral hole, single arrow), black
(labrum), white (fluid in sulcus between labrum and biceps tendon, double
arrow), and black (biceps tendon) areas.
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The absence of the anterosuperior labrum and the presence of a cordlike
middle glenohumeral ligament, known as the Buford complex, was revealed in 2%
of shoulders in this study. Williams et al.
[21] reviewed 200 arthroscopic
videotapes and reported that 1.5% of patients had findings suggestive of a
Buford complex, which should not be interpreted as detached labra.
Some limitations may have affected our study. All subjects were young men,
so the effect of increasing age or sex cannot be evaluated. Normal shoulders
were not verified with arthroscopy or surgery, although no history of shoulder
instability or subjective shoulder symptoms were noted.
In conclusion, knowledge of normal anatomy, anatomic variations, and
pitfalls of labral capsular ligamentous complex is important for the
examination of the shoulder with MR arthrography.
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M. J. Tuite, D. G. Blankenbaker, M. Seifert, A. J. Ziegert, and J. F. Orwin
Sublabral Foramen and Buford Complex: Inferior Extent of the Unattached or Absent Labrum in 50 Patients
Radiology,
April 1, 2002;
223(1):
137 - 142.
[Abstract]
[Full Text]
[PDF]
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Abstract
Introduction
