Scott
A.
Mirowitz,
MD
L. London,
Stanley
#{149}
Ulnar Collateral Pitchers: MR
Ligament Injury Imaging Evaluation’
The ulnar
collateral ligament (UCL) provides stability to the medial aspect of the elbow during valgus stress. Trauma to this ligament may result from repetitive forceful throwing. Diagnosis of UCL injury has been based on clinical findings of
pain
medialjoint ity, as direct
and valgus
instabil-
of this structure available. Eleven basewith clinical evidence of
imaging
has not been ball pitchers
UCL injury
were
magnetic
resonance
Surgical
correlation
six patients,
four
evaluated (MR)
with
imaging.
was obtained of whom
UCL reconstruction.
in
underwent
MR imaging
findings in UCL injury included laxity, irregularity, poor definition, and increased signal intensity within and adjacent to the UCL. These findings reflect the presence of hemorrhage
and/or edema within the UCL due to repeated microtears, which eventually
lead
to weakening
and
possible
disruption of the UCL. Optimization of spatial resolution, signal-to-noise ratio, and other technical factors is
critical
for evaluation of the UCL due to its small size. MR imaging is use-
in documenting
ful
the presence and to the UCL and in
seventy of injury distinguishing this entity causes of elbow pain. Index terms:
Athletic
injuries,
from
42.482
other
Elbow,
#{149}
injuries, 422.482 #{149}Elbow, MR. 422.1214 #{149} Ligaments, injuries, 42.482 #{149} Ligaments, MR. 42.1214 Radiology
1992;
MD
185:573-576
M
resonance has contributed to the noninvasive AGNETIC
ing
tially internal
derangements
I
From
the Departments (S.L.L.),Jewish
ington
University School
University
Medical
of Radiology (5A.M.) Hospital at WashCenter,
of Medicine,
Washington 216 5 Kingshigh-
way Blvd. St Louis, MO 63110. Received 10, 1992; revision requested sion received June 26; accepted reprint requests to 5A.M. ary
C RSNA,
1992
Febru-
March 24; reviJuly 2. Address
(MR) imagsubstanevaluation affecting
of
many
joints, including the knee, shoulder, wrist, temporomandibular joint, and ankle. While some authors believe that the elbow is the joint second most frequently affected by overuse injuries limited
(1), to our knowledge, number of reports
only describe
a
use of MR imaging in the diagnosis of elbow injuries. This is probably related to the technical challenges that the elbow has presented for MR imaging. Recent developments in MR imaging have allowed these challenges to be largely overcome. Athletes who undergo repetitive throwing at high velocity and force are predisposed to development
of elbow injuries.
One of the most
devastating, as athletic greatly hindered because
performance of pain
two
signals
and
T2-weighted in
averaged.
Proton
images
the coronal
scribed alignment is
and
METHODS
The patient population consisted of 11 baseball pitchers (six professional, five amateur), aged 14-34 (mean, 23) years. Clinical presentation in nine of nine patients included pain and tenderness along the medial joint line of the elbow. In addition, valgus instability was documented at physical
density-
were
ac-
and transaxial
planes by using 2,500/30, excitation. Imaging planes
altered biomechanics. The athlete must withdraw from competitive activity for prolonged periods, and often surgical treatment is required. The diagnosis of UCL injury has relied on indirect evidence obtained at physical examination and on plain radiographs, as direct visualization of the UCL has not been possible. The objeetive of this study was to evaluate the ability, with MR imaging, to depict the UCL and to allow for diagnosis of injury to this structure. AND
examination in five of nine patients. These findings led to clinical suspidon of UCL injury. MR imaging was performed with a i.5-T unit (GE Medical Systems, Muwaukee). Patients were examined with a 6.5-inch-diameter surface coil with a shallow cuplike configuration (Medical Advances, Milwaukee). The elbow was placed in the center of the coil and was secured with restraining bands in the fully extended position. The field of view was laterally off centered to allow for imaging of the elbow with the arm at the patient’s side. Ti-weighted images were acquired in the coronal, transaxial, and sagittal planes by using 500/20 (repetition time msec/echo time msec) and
quired
common injuries in such athletes is trauma to the ulnar collateral ligament (UCL). The presence of UCL injury in a throwing athlete is often
MATERIALS
and Surgery
In Baseball
80 and
one
were preto allow for true respect to the elbow
graphically with
joint. Additional
imaging
parameters
included 3-mm section thickness with a i-mm intersection gap, 14-i6-cm field of view, and 192 x 256 imaging matrix.
Spatial
presaturation
was
used
to decrease
pulsation artifacts, and oversampling (no phase wrap) was used to prevent aliasing artifacts.
RESULTS
The
bundle of the UCL was best seen on coronal Ti-weighted or proton density-weighted MR images. On these images, the UCL was depicted as a thin band of low signal intensity that extended along the medialjoint
anterior
line
of the
elbow.
The
poste-
nor and transverse components of the UCL were not discretely visualized. The UCL was determined to be nor-
Abbreviation:
ment.
UCL
=
ulnar
collateral
liga-
mal in three of 1 1 patients. The final clinical diagnoses also concurred with this assessment, as medial elbow pain was ultimately attributed to ulnar nerve impingement due to osteophyte formation in two patients (both of whom underwent surgical deeompression) and to muscular inflammation in one patient. Osteophytes were also seen on plain radiographs obtamed before MR imaging. In none of these patients was valgus instability of the elbow manifested at clinical examination. The clinical course of the remaining eight patients indicated injury to the UCL. In four of eight patients, conservative measures were ineffective in alleviating
symptoms,
and
UCL
re-
with
ulnar nerve transfer was performed. Severe injury involving the UCL was confirmed surgically in these four patients, all of whom were professional athletes. The remaining four patients with presumed UCL injury were undergoing nonoperative management at the time of this writing. MR imaging findings in the presenee of UCL injury included regions of abnormal increased signal intensity within and surrounding the anterior bundle of the UCL. While these signal construction
intensity
abnormalities
were
mani-
fested
on Ti-weighted, as well as proton densityand T2-weighted images, findings were consistently more prominent and extensive on the latter images. The signal intensity alterations were of variable location and extent, predominating in the proximal (n = 3) or distal (n = 2) aspects of the UCL or occurring diffusely throughout the UCL (n = 3). Alterations of morphologic
characteristics
also
dem-
onstrated on MR images were due to UCL injury. In six patients, poor definition of the margins of the UCL was apparent and, when particularly severe, led to poor visualization of the UCL (n = 2). The UCL appeared lax and redundant without apparent discontinuity in two patients, while in the remaining patients it maintained a taut appearance. Focal discontinuity of the distal UCL was apparent in one patient. In all patients who underwent sun-
gery, the
anterior
bundle
of the
UCL
demonstrated evidence of scarring and inflammatory changes. In one surgical patient each, a longitudinal split in the UCL fibers and partial tearing of the medial flexor muscle bundle from the medial epicondyle were observed; these observations correlated abnormal
574
with signal
Radiology
#{149}
the observation intensity on
of
MR im-
ages. Degenerative and reactive changes were present at histologic examination in the reseeted UCL fragments, in addition to foci of calciflealion in two patients. Ancillary
bone
abnormalities
1).
DISCUSSION The UCL, also referred to as the medial collateral ligament of the elbow, serves as the primary means of maintaining elbow stability in the presence of valgus stress (2). Minor additional support is provided by the joint capsule, joint surfaces, and museulature of the forearm flexors. The UCL is actually a ligamentous complex that comprises three separate ligaments: the anterior, posterior, and transverse UCLs (Fig i). The anterior bundle is the dominant component and is substantially larger, better defined, and more functionally important than the other components of the UCL (2,3). The anterior UCL is a cordlike structure 27 mm in mean length and 4-5 mm in mean width (4). It arises from the inferior surface of the medial humeral epicondyle and inserts
ulnar bundle
along
the
medial
aspect
of the
cononoid process. The posterior is smaller and has a fanlike
configuration.
The
transverse
liga-
ment is very small and often difficult to define, or may be absent. The fibers of the anterior UCL are taut when the forearm
is extended,
while
bundle
in-
eluded osteophytes in seven patients. These osteophytes involved the trochlea (n = 3), capitulum humeri (eapitellum) (n = i), troehlea and eapitellum (n = 1), trochlea and coronoid process of the ulna (n = i), and olecranon (n = i). A small cyst was present in the capitellum of one patient. Aneillany soft-tissue abnormalities included the presence of joint effusion (n = ii), edema and poor definition of the ulnan nerve (n = 2), fluid within the common flexor tendon sheath (n = 2), and edema within the supinator musele(n=
Anterior
those
of
the posterior UCL are relaxed. During forearm flexion, the situation is reversed. Experimental transection of the anterior UCL results in severe elbow instability when valgus stress is applied (3,5). The posterior and transverse ligaments have not, however, been found to have a definite functional role in terms of maintaining elbow stability. Injuries to the UCL occur primarily in throwing athletes, including baseball pitchers and javelin throwers. During the process of throwing, the elbow is subjected to severe valgus
Posterior bundle
:
ligament
55 Transverse
Figure
1.
bow shows complex.
stress
while
Schematic
the three
illustration
components
in partial
flexion.
of the
el-
of the UCL
The
me-
ehanies and forceful and repetitive nature of throwing result in ongoing trauma to the UCL (i). The anterior UCL repeatedly sustains mierotears, which result in hemorrhage and edema within and around the ligament (2). Continued stress leads to weakening and laxity of the UCL, and complete ligamentous disruption or detachment from bone eventually may ensue. Athletes with UCL injury present clinically with medial joint pain and tenderness that is accentuated by recent throwing (1). Increased valgus angulation of the forearm ( > 5#{176}) with the arm in partial flexion may be elieited at physical examination or on stress radiographs, because of UCL insufficiency (6). Because the ulnar nerve is immediately adjacent to the UCL, symptoms of ulnar nerve compression may occur (2). Patients with chronic UCL injury may also develop elbow flexion contractures, which are attributed
to a physiologic
reparative
attempt. While findings at physical examinalion may suggest the diagnosis of UCL injury, other entities such as muscular or bone-related inflammalion may also lead to medial elbow pain and tenderness. A noninvasive means of providing direct visualization of the UCL has not been previously available. Arthrography has been used to demonstrate extravasalion of contrast material outside the joint capsule in the presence of complete UCL tears (2,7). Anthrograms, however, are useful only if obtained early after acute UCL rupture. Most UCL injuries do not occur under these conditions and would therefore not be depicted with anthrography. This is the first report, to our knowledge, to describe the use of MR imaging to diagnose internal derangement of the elbow, including injury to the UCL. We were able to see the UCL as a thin linear band extending along the medial aspect of the elbow joint on November
1992
must
a.
b.
Figure 2. Normal UCL (arrows) is demonstrated on coronal (a) TI-weighted (550/16) and (b) T2-weighted (2,000/80) images obtained in a patient without clinical evidence of UCL injury.
and
The
normal
an absence
ligament
of internal
is characterized
by a straight
signal
with
intensity
course,
all pulse
discretely
defined
margins,
sequences.
be
surface
a.
b.
Figure 3. (a) Proton density-weighted (2,500/30) and (b) T2-weighted (2,500/80) coronal images obtained in a baseball pitcher with UCL injury. The UCL is ill defined, with increased signal intensity indicating fluid surrounding its margins, particularly medially (arrow). In addition, a focus of abnormal increased signal intensity is present within the substance of the proximal UCL (arrowhead).
MR images (Fig 2) (8). The normal UCL is characterized by a uniform low signal intensity, similar to the appearanee of other ligamentous and tendinous structures on MR images, attributable to their highly ordered structure and collagenous composilion (9). The UCL was best seen on coronal Ti-weighted on proton density-weighted images. These images allowed for visualization of the entire extent of the anterior bundle of the UCL, which was taut, since the elbow was imaged while in full extension. The posterior and transverse eompoV,1,imo
1R
#{149} Mirnhc,r
nents
of the
UCL
complex
were
not
discretely seen, probably because of their small size, inconsistent presence, and laxity during elbow extension. While definition of the posterior bundle would likely be improved on images acquired with the elbow flexed, this this
possibility structure
was is not
not pursued, since believed to be
clinically significant and does not eontribute to the symptom complex occurling in the patients in our series. Optimization
nique was evaluation
of
found of the
MR
imaging
tech-
to be critical in the UCL. A surface coil
used
to increase
the
signal-to-
noise ratio. The signal-to-noise ratio is otherwise severely limited, given the small field of view, high-resolution imaging matrix, and thin sections, which together result in small voxel sizes. It is essential to limit patient motion, so that blurring and ghosting artifacts may be avoided. Patient motion is most frequently the result of physical discomfort experienced when the injured elbow must be held motionless in full extension for nelatively long periods. Use of off-center field of view allows for imaging of the elbow to be accomplished with the arm at the patient’s side. Otherwise, the elbow must be placed near the isocenter of the magnet, which requires that the arm be positioned over the head. Severe discomfort is rapidly experienced, and often results in substantial image degradation. We found that use of a cup-shaped coil,
originally
designed
for
shoulder imaging, was ideal for imaging of the elbow. The configuration and size of the coil allowed the elbow to rest comfortably within the depressed center of the coil, lending some stabilization to the elbow, while also providing excellent signal-tonoise ratio throughout the entire field of view. Use of restraining bindings across the elbow further decreases the possibility of patient motion. Finally, it is important to position the elbow in full extension with the hand supinated to visualize the full extent of the anterior UCL. The findings demonstrated with MR imaging in our study correspond closely to the pathologic findings described previously. Increased signal intensity within and surrounding the UCL was observed with both Tiweighted and T2-weighted pulse sequenees, corresponding to the presenee of hemorrhage and edema (Figs 3, 4). In addition
to the
abnormal
intensity,
signal
presence
of
morpho-
logic alterations were also documented. These findings included poor definition, attenuation, and laxity of the anterior UCL. In one patient, cornplete disruption of the UCL was demonstrated (Fig 5). Secondary findings depicted on MR images consisted of elbow joint effusion and osteophytes along the articular surfaces. Additional abnormalities may also occur in the setting of chronic UCL injury. The lack of valgus stability of the elbow allows for transmission of compressive
forces
Ian joint, may
the
occur
the
to the
where (2).
olecranon
lateral
bone The
radioeapitel-
impaction medial
aspect
process
may R;inv,
injury of
also .
‘7
impact fossa,
on the leading
wall of the to development
oleeranon of loose
bodies
(i). of UCL injury are initially managed with a program of nest, heat or ice application, muscle strengthening exercises, and administration of Cases
systemic antiinflammatory tions or local steroid
medica-
injections (10). Pain, however, is often persistent, and the ability to effectively perform in competitive
athletics
is frequently
not
regained. When a trial of such conservative measures fails, surgical therapy is often undertaken. Direct primary anastomosis
tached
or reinsertion
UCL
condyle
into
or ulna
the can
of a de-
medial
epi-
occasionally
be
performed. Much more frequently, however, the UCL is too friable to allow for primary repair, and UCL reconstruction
is required
to it during
surgery
or during
the postoperative period from swelling and hematoma. Ulnan nerve injury is the most frequent surgical complication related to this procedure, and patients may experience ulnar nerve palsy or paresthesias that necessitate repeated surgery (10). Postoperative rehabilitation consists of splints, orthotic devices, and an exercise program that is designed to develop strength and range of motion. At least 1 year is required to allow for complete incorporation and vaseularization of the tendon graft. After a 12-18-month recuperative period, most patients are able to resume competitive athletic activity at their previous level of performance (10). In summary, MR imaging has been used to visualize injuries involving the UCL. In the presence of UCL injury, MR imaging demonstrates ligamentous laxity, poor definition, and irregularity, as well as increased signal intensity within and adjacent to the UCL. These findings reflect the presence of hemorrhage and edema
576
Radiology
#{149}
4. Increased within the
signal proximal
intensity surrounds the UCL (arrow) on coronal
weighted somewhat
(2,200/80) images obtained less prominent than those
weighted
image
UCL, with a focus of abnormal (a) Ti-weighted (400/12) and
in a baseball pitcher displayed in Figure
signal (b) T2-
in-
with UCL injury. These findings are 3 and are best depicted on the T2-
(b).
(10).
In our patients, a tendon graft was harvested from the palmaris longus; when this tendon is absent the plantaris, Achilles, toe extensor, or fascia lata femoris may be used. The tendon graft is passed through holes that are drilled in the medial epicondyle and ulna at the sites of UCL insertion, and the native UCL is oversewn around the graft. The ulnar nerve is dissected and transferred anteriorly, to prevent injury
b.
a.
Figure tensity
a.
b.
Figure weighted tracted
5.
Complete (2,250/30) proximally
nal intensity
rupture of the distal UCL is demonstrated and (b) T2-weighted (2,250/80) images. from the site of detachment (arrow), and
surrounding
the UCL represents
within the UCL due to mienotears resulting from repetitive injury. Use of appropriate surface coil, imaging planes, and optimization of spatial resolution and signal-to-noise ratio are critical to evaluation of the UCL. Our results indicate that MR imaging is useful in documenting the presence and severity of UCL injury, and in distinguishing causes of elbow
this entity pain.
from
edema
4.
5.
6.
hemorrhage.
Morrey BF, An KNA. Functional anatomy of the ligaments of the elbow. Clin Orthop 1985; 201:84-90. Hotchkiss RN, Weiland AJ. Valgus stability of the elbow. J Orthop Res 1987; 5:372377. Morrey BF, Tanaka S. An KNA. Valgus stability of the elbow: a definition of primary and secondary contraints. Clin Orthop 1991; 265:187-195.
7.
Kuroda
8.
ligament tears of the elbow thop 1986; 208:266-271. Macrander SJ. The elbow.
other
a
and
on coronal (a) proton densityThe UCL is thickened and reextensive abnormal increased sig-
S, Sakamaki
WD, Lawson
References 15
2.
35
Jobe FW, Nuber C. Throwing injuries of the elbow. Clin Sports Med 1986; 5:621636. Bennett JB, Tullos HS. Ligamentous and articular injuries in the athlete. In: Morrey BF, ed. The elbow and its disorders. Philadelphia: Saunders, 1985; 502-522. SojbjergJO, Ovesen J, Nielsen S. Experimental elbow instability after transection of the medial collateral ligament. Clin Orthop 1987; 218:186-190.
9.
10.
K.
Ulnar
collateral
joint.
Clin
Or-
In: Middleton
TL, eds. Anatomy
and MRI of
the joints: a multiplanar atlas. New York: Raven, 1989; 49-81. Beltran J, Noto AM, Herman U, Lubbers LM. Tendons: high field-strength surface coil MR imaging. Radiology 1987; 162:735740. Jobe FW, Stark H, Lombardo SJ. Reconstruction of the ulnar collateral ligament in athletes. J Bone Joint Surg (Am] 1986; 68: 1158-1163.
November
1992
A.
Mirowitz,
MD
L. London,
Stanley
#{149}
Ulnar Collateral Pitchers: MR
Ligament Injury Imaging Evaluation’
The ulnar
collateral ligament (UCL) provides stability to the medial aspect of the elbow during valgus stress. Trauma to this ligament may result from repetitive forceful throwing. Diagnosis of UCL injury has been based on clinical findings of
pain
medialjoint ity, as direct
and valgus
instabil-
of this structure available. Eleven basewith clinical evidence of
imaging
has not been ball pitchers
UCL injury
were
magnetic
resonance
Surgical
correlation
six patients,
four
evaluated (MR)
with
imaging.
was obtained of whom
UCL reconstruction.
in
underwent
MR imaging
findings in UCL injury included laxity, irregularity, poor definition, and increased signal intensity within and adjacent to the UCL. These findings reflect the presence of hemorrhage
and/or edema within the UCL due to repeated microtears, which eventually
lead
to weakening
and
possible
disruption of the UCL. Optimization of spatial resolution, signal-to-noise ratio, and other technical factors is
critical
for evaluation of the UCL due to its small size. MR imaging is use-
in documenting
ful
the presence and to the UCL and in
seventy of injury distinguishing this entity causes of elbow pain. Index terms:
Athletic
injuries,
from
42.482
other
Elbow,
#{149}
injuries, 422.482 #{149}Elbow, MR. 422.1214 #{149} Ligaments, injuries, 42.482 #{149} Ligaments, MR. 42.1214 Radiology
1992;
MD
185:573-576
M
resonance has contributed to the noninvasive AGNETIC
ing
tially internal
derangements
I
From
the Departments (S.L.L.),Jewish
ington
University School
University
Medical
of Radiology (5A.M.) Hospital at WashCenter,
of Medicine,
Washington 216 5 Kingshigh-
way Blvd. St Louis, MO 63110. Received 10, 1992; revision requested sion received June 26; accepted reprint requests to 5A.M. ary
C RSNA,
1992
Febru-
March 24; reviJuly 2. Address
(MR) imagsubstanevaluation affecting
of
many
joints, including the knee, shoulder, wrist, temporomandibular joint, and ankle. While some authors believe that the elbow is the joint second most frequently affected by overuse injuries limited
(1), to our knowledge, number of reports
only describe
a
use of MR imaging in the diagnosis of elbow injuries. This is probably related to the technical challenges that the elbow has presented for MR imaging. Recent developments in MR imaging have allowed these challenges to be largely overcome. Athletes who undergo repetitive throwing at high velocity and force are predisposed to development
of elbow injuries.
One of the most
devastating, as athletic greatly hindered because
performance of pain
two
signals
and
T2-weighted in
averaged.
Proton
images
the coronal
scribed alignment is
and
METHODS
The patient population consisted of 11 baseball pitchers (six professional, five amateur), aged 14-34 (mean, 23) years. Clinical presentation in nine of nine patients included pain and tenderness along the medial joint line of the elbow. In addition, valgus instability was documented at physical
density-
were
ac-
and transaxial
planes by using 2,500/30, excitation. Imaging planes
altered biomechanics. The athlete must withdraw from competitive activity for prolonged periods, and often surgical treatment is required. The diagnosis of UCL injury has relied on indirect evidence obtained at physical examination and on plain radiographs, as direct visualization of the UCL has not been possible. The objeetive of this study was to evaluate the ability, with MR imaging, to depict the UCL and to allow for diagnosis of injury to this structure. AND
examination in five of nine patients. These findings led to clinical suspidon of UCL injury. MR imaging was performed with a i.5-T unit (GE Medical Systems, Muwaukee). Patients were examined with a 6.5-inch-diameter surface coil with a shallow cuplike configuration (Medical Advances, Milwaukee). The elbow was placed in the center of the coil and was secured with restraining bands in the fully extended position. The field of view was laterally off centered to allow for imaging of the elbow with the arm at the patient’s side. Ti-weighted images were acquired in the coronal, transaxial, and sagittal planes by using 500/20 (repetition time msec/echo time msec) and
quired
common injuries in such athletes is trauma to the ulnar collateral ligament (UCL). The presence of UCL injury in a throwing athlete is often
MATERIALS
and Surgery
In Baseball
80 and
one
were preto allow for true respect to the elbow
graphically with
joint. Additional
imaging
parameters
included 3-mm section thickness with a i-mm intersection gap, 14-i6-cm field of view, and 192 x 256 imaging matrix.
Spatial
presaturation
was
used
to decrease
pulsation artifacts, and oversampling (no phase wrap) was used to prevent aliasing artifacts.
RESULTS
The
bundle of the UCL was best seen on coronal Ti-weighted or proton density-weighted MR images. On these images, the UCL was depicted as a thin band of low signal intensity that extended along the medialjoint
anterior
line
of the
elbow.
The
poste-
nor and transverse components of the UCL were not discretely visualized. The UCL was determined to be nor-
Abbreviation:
ment.
UCL
=
ulnar
collateral
liga-
mal in three of 1 1 patients. The final clinical diagnoses also concurred with this assessment, as medial elbow pain was ultimately attributed to ulnar nerve impingement due to osteophyte formation in two patients (both of whom underwent surgical deeompression) and to muscular inflammation in one patient. Osteophytes were also seen on plain radiographs obtamed before MR imaging. In none of these patients was valgus instability of the elbow manifested at clinical examination. The clinical course of the remaining eight patients indicated injury to the UCL. In four of eight patients, conservative measures were ineffective in alleviating
symptoms,
and
UCL
re-
with
ulnar nerve transfer was performed. Severe injury involving the UCL was confirmed surgically in these four patients, all of whom were professional athletes. The remaining four patients with presumed UCL injury were undergoing nonoperative management at the time of this writing. MR imaging findings in the presenee of UCL injury included regions of abnormal increased signal intensity within and surrounding the anterior bundle of the UCL. While these signal construction
intensity
abnormalities
were
mani-
fested
on Ti-weighted, as well as proton densityand T2-weighted images, findings were consistently more prominent and extensive on the latter images. The signal intensity alterations were of variable location and extent, predominating in the proximal (n = 3) or distal (n = 2) aspects of the UCL or occurring diffusely throughout the UCL (n = 3). Alterations of morphologic
characteristics
also
dem-
onstrated on MR images were due to UCL injury. In six patients, poor definition of the margins of the UCL was apparent and, when particularly severe, led to poor visualization of the UCL (n = 2). The UCL appeared lax and redundant without apparent discontinuity in two patients, while in the remaining patients it maintained a taut appearance. Focal discontinuity of the distal UCL was apparent in one patient. In all patients who underwent sun-
gery, the
anterior
bundle
of the
UCL
demonstrated evidence of scarring and inflammatory changes. In one surgical patient each, a longitudinal split in the UCL fibers and partial tearing of the medial flexor muscle bundle from the medial epicondyle were observed; these observations correlated abnormal
574
with signal
Radiology
#{149}
the observation intensity on
of
MR im-
ages. Degenerative and reactive changes were present at histologic examination in the reseeted UCL fragments, in addition to foci of calciflealion in two patients. Ancillary
bone
abnormalities
1).
DISCUSSION The UCL, also referred to as the medial collateral ligament of the elbow, serves as the primary means of maintaining elbow stability in the presence of valgus stress (2). Minor additional support is provided by the joint capsule, joint surfaces, and museulature of the forearm flexors. The UCL is actually a ligamentous complex that comprises three separate ligaments: the anterior, posterior, and transverse UCLs (Fig i). The anterior bundle is the dominant component and is substantially larger, better defined, and more functionally important than the other components of the UCL (2,3). The anterior UCL is a cordlike structure 27 mm in mean length and 4-5 mm in mean width (4). It arises from the inferior surface of the medial humeral epicondyle and inserts
ulnar bundle
along
the
medial
aspect
of the
cononoid process. The posterior is smaller and has a fanlike
configuration.
The
transverse
liga-
ment is very small and often difficult to define, or may be absent. The fibers of the anterior UCL are taut when the forearm
is extended,
while
bundle
in-
eluded osteophytes in seven patients. These osteophytes involved the trochlea (n = 3), capitulum humeri (eapitellum) (n = i), troehlea and eapitellum (n = 1), trochlea and coronoid process of the ulna (n = i), and olecranon (n = i). A small cyst was present in the capitellum of one patient. Aneillany soft-tissue abnormalities included the presence of joint effusion (n = ii), edema and poor definition of the ulnan nerve (n = 2), fluid within the common flexor tendon sheath (n = 2), and edema within the supinator musele(n=
Anterior
those
of
the posterior UCL are relaxed. During forearm flexion, the situation is reversed. Experimental transection of the anterior UCL results in severe elbow instability when valgus stress is applied (3,5). The posterior and transverse ligaments have not, however, been found to have a definite functional role in terms of maintaining elbow stability. Injuries to the UCL occur primarily in throwing athletes, including baseball pitchers and javelin throwers. During the process of throwing, the elbow is subjected to severe valgus
Posterior bundle
:
ligament
55 Transverse
Figure
1.
bow shows complex.
stress
while
Schematic
the three
illustration
components
in partial
flexion.
of the
el-
of the UCL
The
me-
ehanies and forceful and repetitive nature of throwing result in ongoing trauma to the UCL (i). The anterior UCL repeatedly sustains mierotears, which result in hemorrhage and edema within and around the ligament (2). Continued stress leads to weakening and laxity of the UCL, and complete ligamentous disruption or detachment from bone eventually may ensue. Athletes with UCL injury present clinically with medial joint pain and tenderness that is accentuated by recent throwing (1). Increased valgus angulation of the forearm ( > 5#{176}) with the arm in partial flexion may be elieited at physical examination or on stress radiographs, because of UCL insufficiency (6). Because the ulnar nerve is immediately adjacent to the UCL, symptoms of ulnar nerve compression may occur (2). Patients with chronic UCL injury may also develop elbow flexion contractures, which are attributed
to a physiologic
reparative
attempt. While findings at physical examinalion may suggest the diagnosis of UCL injury, other entities such as muscular or bone-related inflammalion may also lead to medial elbow pain and tenderness. A noninvasive means of providing direct visualization of the UCL has not been previously available. Arthrography has been used to demonstrate extravasalion of contrast material outside the joint capsule in the presence of complete UCL tears (2,7). Anthrograms, however, are useful only if obtained early after acute UCL rupture. Most UCL injuries do not occur under these conditions and would therefore not be depicted with anthrography. This is the first report, to our knowledge, to describe the use of MR imaging to diagnose internal derangement of the elbow, including injury to the UCL. We were able to see the UCL as a thin linear band extending along the medial aspect of the elbow joint on November
1992
must
a.
b.
Figure 2. Normal UCL (arrows) is demonstrated on coronal (a) TI-weighted (550/16) and (b) T2-weighted (2,000/80) images obtained in a patient without clinical evidence of UCL injury.
and
The
normal
an absence
ligament
of internal
is characterized
by a straight
signal
with
intensity
course,
all pulse
discretely
defined
margins,
sequences.
be
surface
a.
b.
Figure 3. (a) Proton density-weighted (2,500/30) and (b) T2-weighted (2,500/80) coronal images obtained in a baseball pitcher with UCL injury. The UCL is ill defined, with increased signal intensity indicating fluid surrounding its margins, particularly medially (arrow). In addition, a focus of abnormal increased signal intensity is present within the substance of the proximal UCL (arrowhead).
MR images (Fig 2) (8). The normal UCL is characterized by a uniform low signal intensity, similar to the appearanee of other ligamentous and tendinous structures on MR images, attributable to their highly ordered structure and collagenous composilion (9). The UCL was best seen on coronal Ti-weighted on proton density-weighted images. These images allowed for visualization of the entire extent of the anterior bundle of the UCL, which was taut, since the elbow was imaged while in full extension. The posterior and transverse eompoV,1,imo
1R
#{149} Mirnhc,r
nents
of the
UCL
complex
were
not
discretely seen, probably because of their small size, inconsistent presence, and laxity during elbow extension. While definition of the posterior bundle would likely be improved on images acquired with the elbow flexed, this this
possibility structure
was is not
not pursued, since believed to be
clinically significant and does not eontribute to the symptom complex occurling in the patients in our series. Optimization
nique was evaluation
of
found of the
MR
imaging
tech-
to be critical in the UCL. A surface coil
used
to increase
the
signal-to-
noise ratio. The signal-to-noise ratio is otherwise severely limited, given the small field of view, high-resolution imaging matrix, and thin sections, which together result in small voxel sizes. It is essential to limit patient motion, so that blurring and ghosting artifacts may be avoided. Patient motion is most frequently the result of physical discomfort experienced when the injured elbow must be held motionless in full extension for nelatively long periods. Use of off-center field of view allows for imaging of the elbow to be accomplished with the arm at the patient’s side. Otherwise, the elbow must be placed near the isocenter of the magnet, which requires that the arm be positioned over the head. Severe discomfort is rapidly experienced, and often results in substantial image degradation. We found that use of a cup-shaped coil,
originally
designed
for
shoulder imaging, was ideal for imaging of the elbow. The configuration and size of the coil allowed the elbow to rest comfortably within the depressed center of the coil, lending some stabilization to the elbow, while also providing excellent signal-tonoise ratio throughout the entire field of view. Use of restraining bindings across the elbow further decreases the possibility of patient motion. Finally, it is important to position the elbow in full extension with the hand supinated to visualize the full extent of the anterior UCL. The findings demonstrated with MR imaging in our study correspond closely to the pathologic findings described previously. Increased signal intensity within and surrounding the UCL was observed with both Tiweighted and T2-weighted pulse sequenees, corresponding to the presenee of hemorrhage and edema (Figs 3, 4). In addition
to the
abnormal
intensity,
signal
presence
of
morpho-
logic alterations were also documented. These findings included poor definition, attenuation, and laxity of the anterior UCL. In one patient, cornplete disruption of the UCL was demonstrated (Fig 5). Secondary findings depicted on MR images consisted of elbow joint effusion and osteophytes along the articular surfaces. Additional abnormalities may also occur in the setting of chronic UCL injury. The lack of valgus stability of the elbow allows for transmission of compressive
forces
Ian joint, may
the
occur
the
to the
where (2).
olecranon
lateral
bone The
radioeapitel-
impaction medial
aspect
process
may R;inv,
injury of
also .
‘7
impact fossa,
on the leading
wall of the to development
oleeranon of loose
bodies
(i). of UCL injury are initially managed with a program of nest, heat or ice application, muscle strengthening exercises, and administration of Cases
systemic antiinflammatory tions or local steroid
medica-
injections (10). Pain, however, is often persistent, and the ability to effectively perform in competitive
athletics
is frequently
not
regained. When a trial of such conservative measures fails, surgical therapy is often undertaken. Direct primary anastomosis
tached
or reinsertion
UCL
condyle
into
or ulna
the can
of a de-
medial
epi-
occasionally
be
performed. Much more frequently, however, the UCL is too friable to allow for primary repair, and UCL reconstruction
is required
to it during
surgery
or during
the postoperative period from swelling and hematoma. Ulnan nerve injury is the most frequent surgical complication related to this procedure, and patients may experience ulnar nerve palsy or paresthesias that necessitate repeated surgery (10). Postoperative rehabilitation consists of splints, orthotic devices, and an exercise program that is designed to develop strength and range of motion. At least 1 year is required to allow for complete incorporation and vaseularization of the tendon graft. After a 12-18-month recuperative period, most patients are able to resume competitive athletic activity at their previous level of performance (10). In summary, MR imaging has been used to visualize injuries involving the UCL. In the presence of UCL injury, MR imaging demonstrates ligamentous laxity, poor definition, and irregularity, as well as increased signal intensity within and adjacent to the UCL. These findings reflect the presence of hemorrhage and edema
576
Radiology
#{149}
4. Increased within the
signal proximal
intensity surrounds the UCL (arrow) on coronal
weighted somewhat
(2,200/80) images obtained less prominent than those
weighted
image
UCL, with a focus of abnormal (a) Ti-weighted (400/12) and
in a baseball pitcher displayed in Figure
signal (b) T2-
in-
with UCL injury. These findings are 3 and are best depicted on the T2-
(b).
(10).
In our patients, a tendon graft was harvested from the palmaris longus; when this tendon is absent the plantaris, Achilles, toe extensor, or fascia lata femoris may be used. The tendon graft is passed through holes that are drilled in the medial epicondyle and ulna at the sites of UCL insertion, and the native UCL is oversewn around the graft. The ulnar nerve is dissected and transferred anteriorly, to prevent injury
b.
a.
Figure tensity
a.
b.
Figure weighted tracted
5.
Complete (2,250/30) proximally
nal intensity
rupture of the distal UCL is demonstrated and (b) T2-weighted (2,250/80) images. from the site of detachment (arrow), and
surrounding
the UCL represents
within the UCL due to mienotears resulting from repetitive injury. Use of appropriate surface coil, imaging planes, and optimization of spatial resolution and signal-to-noise ratio are critical to evaluation of the UCL. Our results indicate that MR imaging is useful in documenting the presence and severity of UCL injury, and in distinguishing causes of elbow
this entity pain.
from
edema
4.
5.
6.
hemorrhage.
Morrey BF, An KNA. Functional anatomy of the ligaments of the elbow. Clin Orthop 1985; 201:84-90. Hotchkiss RN, Weiland AJ. Valgus stability of the elbow. J Orthop Res 1987; 5:372377. Morrey BF, Tanaka S. An KNA. Valgus stability of the elbow: a definition of primary and secondary contraints. Clin Orthop 1991; 265:187-195.
7.
Kuroda
8.
ligament tears of the elbow thop 1986; 208:266-271. Macrander SJ. The elbow.
other
a
and
on coronal (a) proton densityThe UCL is thickened and reextensive abnormal increased sig-
S, Sakamaki
WD, Lawson
References 15
2.
35
Jobe FW, Nuber C. Throwing injuries of the elbow. Clin Sports Med 1986; 5:621636. Bennett JB, Tullos HS. Ligamentous and articular injuries in the athlete. In: Morrey BF, ed. The elbow and its disorders. Philadelphia: Saunders, 1985; 502-522. SojbjergJO, Ovesen J, Nielsen S. Experimental elbow instability after transection of the medial collateral ligament. Clin Orthop 1987; 218:186-190.
9.
10.
K.
Ulnar
collateral
joint.
Clin
Or-
In: Middleton
TL, eds. Anatomy
and MRI of
the joints: a multiplanar atlas. New York: Raven, 1989; 49-81. Beltran J, Noto AM, Herman U, Lubbers LM. Tendons: high field-strength surface coil MR imaging. Radiology 1987; 162:735740. Jobe FW, Stark H, Lombardo SJ. Reconstruction of the ulnar collateral ligament in athletes. J Bone Joint Surg (Am] 1986; 68: 1158-1163.
November
1992
