Of 27 patients who underwent magnetic resonance (MR) imaging of the elbow, 11 underwent elbow arthroscopy and/or an open surgical procedure. Surgical findings were compared with those from MR imaging. Five healthy volunteers also underwent MR imaging to demonstrate anatomic relationships. Transchondral fracture (osteochondritis dissecans) was identified in three of the 11 patients and was proved at surgery. Loose bodies were suspected at MR imaging in the three patients but were found in only two. One complete avulsion of the ulnar collateral ligament (UCL) and four cases of intact, thickened UCLs were identified at MR imaging and surgery. Loose bodies from the olecranon tip were found in three patients at surgery but were seen on MR images in only two. MR imaging depicted olecranal osteophytes in three cases, which were confirmed at surgery. Two complete avulsions of the biceps tendon and one partial triceps tendon tear were identified with MR imaging and proved at surgery. A postoperative soft-tissue infection and a synovial cyst were also seen at MR imaging and surgery. These results suggest that MR imaging is useful in the evaluation of the elbow. Index

terms:

Elbow,

injuries,

422.482

MR, 422.i2i4 #{149} Ligaments, injuries, Ligaments, MR, 42.i214 #{149} Tendons, 42.482 #{149} Tendons, MR. 42,1214 Radiology

i992;

#{149} Elbow, 42.482 injuries,

184:525-529

I From the Department of Diagnostic Radiology, Magnetic Resonance Imaging Center, Siemens Medical Systems Muscuhoskeletal Research-Reference Site, Healthsouth Doctors’ Hospital, 5000 University Dr. Coral Gables, FL 33146. Received January 22, 1992; revision requested February 26; revision received March 20; accepted March 27. Address reprint requests to the author. C RSNA, 1992

M

resonance (MR) imaging has proved useful in the evaluation of tendons and fibrocartilage in the knee, shoulder, ankle, and wrist (1-6). The anterior cruciate ligament, the small ankle ligaments, and the intracarpal ligaments of the wrist can be routinely identified with stateof-the-art MR imaging systems. These ligaments are of similar size or smaller than the ulnar collateral ligaments (UCLs) and radial collateral ligaments (RCLs) of the elbow. It has recently been shown that complete anterior cruciate ligament tears can usually be distinguished from injuries of lesser severity with high-resolution proton-density and T2-weighted imaging (7). This requires the use of technologically advanced surface coils and pulse sequences capable of producing thin sections and small fields of view with a high signal-to-noise ratio. If these criteria are met, MR imaging seems ideally suited for the visualization of pathologic processes affecting the elbow because of its ability to depict ligaments and tendons with superior resolution. The elbow is a highly mobile hinge joint; half of its stability is a function of its bony configuration and half is a function of its ligamentous and capsular configuration (8). The UCL cornplex consists of anterior, posterior, and oblique (ie, the transverse ligament) bundles. The anterior bundle is the primary contributor to medial stability (ie, it resists valgus stress) and can best be visualized in the coronal plane (Fig 1). Injury to the UCL is not uncommon in throwing athletes (9-11). The RCL complex consists of the RCL “proper,” which originates from the lateral epicondyle and inserts onto the annular ligament; the accessory collateral ligament and the lateral UCL also contribute to the RCL complex. Functionally, the RCL cornplex does not contribute to joint stabifity to the same degree as the UCL AGNETIC

complex (10). The anconeus muscle traverses the articulation laterally and contributes substantially to joint stability. To a lesser extent, the flexor forearm mass affords dynamic support medially (10). Important musculotendinous structures around the elbow include the elbow flexors, the brachialis, the biceps, and the brachioradialis. The biceps tendon courses obliquely in an anterior to posterior direction to insert on the radial tuberosity. The superficial flexor-pronator group originates from the medial epicondyle and consists of the flexor carpi radialis, flexor digitorum superficialis, pronator teres, palmaris longus, and flexor carpi ulnaris. On the lateral aspect of the elbow, the brachioradialis, extensor carpi radialis longus and brevis, and a portion of the common extensor tendons originate from the lateral epicondylar region. The extensor carpi radialis longus and brevis are important clinically in lateral epicondylitis (ie, tennis elbow) (10). Posteriorly, the triceps tendon inserts onto the olecranon process posterior to the bony tip of the olecranon, which is an intraarticular structure. Olecranal osteophytes and loose bodies within the posterior compartment are important pathologic processes in baseball pitchers (11,12). Although the normal structure of the elbow has been described with MR imaging (13), the purpose of this study is to correlate the MR appearance of several common elbow injuries with the findings obtained at surgery.

MATERIALS

AND

METHODS

Twenty-seven patients underwent imaging of the elbow between May

Abbreviations: steady-state

RCL = collateral

FISP

precession, radial collateral

=

MR 1990

fast imaging with FOV = field of view, ligament, UCL = uhnar

ligament.

525

and November 1991 because of elbow pain or soft-tissue swelling. There were 24 male and three female subjects. Their ages ranged from 11 to 64 years (median age, 26 years). Of this

group,

underwent

teers

11 patients surgery.

also

subsequently

Five

underwent

healthy

volun-

MR imaging

of the

elbow. MR imaging was performed with the patient supine, head first into the magnet. The bottom half of a cylindrical Helmholtz receive-only surface coil was used to evaluate the extremity. The patient was positioned obliquely on the table in a 45#{176} postenor-oblique position, allowing the elbow and coil to rest flat on the table surface. A 240-cm field of view (FOV) axial off-centered pilot image was obtained, and the humeral epicondyles were identified. Then, coronal images were obtained in alignment with All examinations

the

epicondyles.

were

performed

with

a

1.0-T imager (Magnetom SP 42; Siemens Medical Systems, Iselin NJ) with the following parameters: coronal TI-weighted (repetition time msec/echo time msec = 600/20) images with a 20-cm FOV, a 3-mm section thickness, three signals averaged, and a 256 x 256 matrix (phase encoding 20,

X readout); 90)

coronal

images

with

section thickness, and a 200 x 256

dual-echo

a 20-cm

two signals matrix.

(2,000/

FOV,

a 4-mm

averaged,

Three-dimen-

sional fast imaging with steady-state precession (FISP) was performed with a 20-cm FOV, an 8-cm section thickness, and 64 partitions for an effective section thickness of 1.25 mm (30/12, 20-cm FOV, 1.25-mm section thickness, one excitation, 256 x 256 matrix,

12#{176} flip

angle).

The coronal views were used to evatuate the UCL and RCL complexes, the distal humeral articulation for transchondral fracture (also known as osteochondritis dissecans), and the olecranon fossa for fragmentation of the olecranon and loose bodies.

The

sagittal

three-dimensional

im-

ages were used to evaluate the olecranon and to determine the presence of loose bodies. Sagittal and axial dual-echo sequences were performed to evaluate the triceps and biceps tendons when clinically indicated. The MR imaging results were compared with surgical findings in 1 1 patients. All 11 patients had undergone elbow arthroscopy with anterior and posterior portals. Open incisions were performed for ligament and tendon repairs and for removal of large loose bodies or osteophytes.

RESULTS Normal

Findings

The radial head, ulna, olecranon, and distal humerus have homogeneous signal intensity throughout the marrow on spin-echo images. Musculotendinous attachments to the epicondyles appear smooth and uninterrupted on Ti-weighted coronal images (Fig 1). High signal intensity within the musculotendinous attach526

#{149} Radiology

b.

a.

Figure 1. Coronal Ti-weighted MR images (600/20). (a) MR image of normal UCL. The primary contributor to stability is the anterior band of the UCL (arrow). It appears smooth and thin and interdigitates with fat of high signal intensity at the humeral attachment. (b) MR image of normal capiteltum and UCL. The articutar plate of the capitetlum appears smooth and

regular cernible

in the coronal plane. (arrow). h = humerus,

The r

UCL was imaged =

radial

slightly

anterior

to its axis but is still dis-

head.

ments and adjacent soft tissues is not normally present on T2-weighted irnages, and the low-signal-intensity cortical bone of the epicondyles appears smooth and regular. The subchondral bone of the articular surfaces also appears smooth and is visualized extrernely well on the three-dirnensional FISP images. Imaging in the coronal plane dernonstrates the anterior bundle of the UCL along its axis when the elbow is in extension (Fig 1). The fibers of this ligament appear as well-defined, lowsignal-intensity striations that interdigitate with high-signal-intensity fatty tissue of the humeral attachment on Ti-weighted images. The proximal attachment of the UCL demonstrates moderately low signal intensity on T2-weighted images. The RCL cornplex is not as well defined on the coronal views but demonstrates uniform low signal intensity with spinecho pulse sequences. Three-dirnensional coronal FISP did not delineate ligamentous structures as well as spin-echo imaging, despite the thin, contiguous 1.25-mm sections. The biceps tendon (Figs 2, 3b) courses obliquely in an anterior to posterior direction to insert at the anteromedial aspect of the radius distal to the radial head (at the posterior aspect of the radial tuberosity). It appears round and of low signal intensity on spin-echo images, and the insertion site is visualized best on axial images. The triceps tendon insertion into the olecranon is well demonstrated on sagittal images (Fig 3) and should appear taut when the elbow is flexed. The olecranon process ap-

Figure 2. Axial Ti-weighted MR image (600/20) shows biceps tendon (arrow). At the level of the radial head (r), the tendon appeared round and had homogeneous low signal intensity with alt pulse sequences. U = ulna.

peared smooth on both the sagittal and coronal images. The olecranon bursa did not contain fluid on the T2weighted images in normal elbows. Transchondral

Fracture

Transchondral fracture of the capitellum was seen in three patients. The coronal Ti-weighted images showed subchondral low signal intensity that extended into the marrow fat (Fig 4). In two patients, fluid of high signal intensity was visualized within the defect on T2-weighted images. Loose bodies were identified with MR irnaging in three patients. These loose bodies were suspected on plain radiographs or tomograms in all three patients

but

were

found

at surgery

August

in

1992

a. Figure

b. 3.

MR

images

(600/20)

flexion (a) and extension tal views of the elbow.

show

normal

(b). The biceps h

=

distal

insertion

tendon

humerus,

o

=

of the

triceps

tendon

(straight

arrow) in sagit-

(curved arrow in b) is also visualized on olecranon, r = radius, s = shaft of humerus.

derwent MR imaging. In two patients, loose bodies adjacent to the olecranon were present on MR images and were visualized best with three-dirnensional FISP imaging; loose bodies were found in these locations at surgery (Fig 7). In one patient, a loose body was found at surgery that was not visualized at MR imaging. Olecranal osteophytes were seen with threedimensional FISP imaging in three patients. In one of these patients, the subchondral osteophyte was secondary to a healed olecranal stress fracture. These cases were confirmed at surgery. In four of the six patients, chondrornalacia of the trochlear notch was found at surgery but could not be identified on MR images. Additionally, one patient had hypertrophic synovium, which was not well seen on the MR image. Biceps

Figure (600/20)

Ti-weighted coronal MR image shows transchondral fracture (arrow) of the capitellum. An osteochondral fragment was positioned obliquely in the defect at surgery. r = radial head.

raphy

and/or

trispiral

tomography

showed the transchondral fracture in two patients but did not depict the capitellurn defect in the third. MR irnaging showed the capitellurn defect in all three patients. UCL Five patients demonstrated abnormal UCLs; all were baseball pitchers at the high-school, college, or minorleague level. One patient had cornplete avulsion of the UCL from its humeral attachment, which was proved at surgery (Fig 5). In the other four patients, the UCL appeared thickened, irregular, and had inVolume

MR imaging demonstrated cornplete avulsions of the biceps tendon from the radial tuberosity in two patients, which were proved at surgery (Fig 8). The tendon sheath had moderate to high signal intensity on T2weighted images, and the low-signal-intensity tendon could not be identified in its normal position. The retracted tendon edge could be identified more proximally in each case on MR images. The T2-weighted images were most helpful in delineating the torn tendon.

4.

only two. In the third case, hypertrophic synovium was present at surgery and was removed. This was not identified on the MR image. Plain radiog-

184

Number

#{149}

2

Tendon

Figure 5. T2-weighted coronal MR image (2,000/90) shows avulsion of the UCL from its humerat attachment. A fluid of high signal intensity (solid arrow) is present between the cortex of the humerus and the frayed UCL (open arrows). A single strand of the ligament seems to remain attached laterally. U = utna.

creased signal intensity within its fibers on T2-weighted coronal images. In these four patients, the UCL was thought to be intact but with thickening and inflammation at MR imaging. In all four patients, the UCL was intact at surgery. The UCL was debrided in three patients, and a calcifled loose body within the ligament was

removed

Olecranal Bodies and

Six patients histories

ies and/or

subsequently

in one

Osteophytes

(Fig

6).

and

Loose

with clinical symptoms suggestive of loose bodolecranal osteophytes who underwent surgery un-

Triceps

Tendon

Two patients had avulsions of the triceps tendon. One partial triceps avulsion was visualized with MR imaging and proved at surgery (Fig 9). The tendon was replaced by increased signal intensity at its insertion with all but the T2-weighted sequences, where “normal” appearing tendon of low signal intensity was visualized at the olecranon insertion. This region of tendon maintained a constant relationship to the olecranon with flexion and extension, suggesting that intact fibers attached to the olecranon were present. The second case showed an intact triceps after surgical repair. Increased signal intensity on T2-weighted images was present in the olecranon bursa, and there was enhancement in this region on Ti-weighted images after injection of contrast material (Magnevist; Berlex, Wayne, NJ), which suggested postoperative softtissue infection and bursitis. At surgery, the tendon was intact, and an Radiology

#{149} 527

a. Figure

6.

(30/12) thickened gery. A is seen, opacity graph.

Three-dimensional

shows a calcified UCL, which tow-signal-intensity which correlated at this position

inflammatory from

the

FISP image

loose body within a was proved at surstructure (arrow) with a calcified on a plain radio-

collection olecranon

Juxtarticular

was

FISP images

non tip. A bony sagittal (a) and

loose coronal

(30/12)

show

body (arrow) (b) views.

fragmentation

is present o = olecranon.

with

adjacent

loose

body

formation

to its donor

site

on

at the olecra-

three-dimensional

bursa.

Mass

DISCUSSION These cases illustrate that several soft-tissue and bone lesions responsible for elbow pain can be visualized with MR imaging. Biceps and triceps tendon injuries are particularly well suited for MR imaging because the pattern of injury mimics that for other tendons, which have been well described previously (ie, Achilles tendon) (14). Ligarnentous injury frequently involves the UCL, especially in throwing athletes. These athletes frequently develop olecranal osteophytes and posterior compartment loose bodies as well. Plain radiography and complex motion tomography are extremely valuable and should be performed routinely in this population. Some loose bodies are extremely difficult to identify on MR images but may be obvious on plain radiographs. Additionally, bone fragments may be Radiology

#{149}

b.

7.

drained

One patient had a 3-cm mass in the medial soft tissues adjacent to the elbow joint. The mass was multilocular and had high signal intensity similar to that of fluid on T2-weighted images. The MR imaging features were suggestive of a synovial cyst. This collection was drained after administration of local anesthesia, and its contents were consistent with a synovial cyst. The mass did not recur after 1-year follow-up.

528

Figure

Figure 8. Axial T2-weighted MR image (2,000/90) shows complete avutsion of the biceps tendon. Fluid (arrow) is seen adjacent to the radial tuberosity and completely filling the tendon sheath. The torn tendon edge could not be identified at this level.

Figure 9. Sagittal Ti-weighted (600/20) of partial triceps tear. nat intensity is present within sertion (arrow). o = olecranon.

MR image Increased sigthe triceps in-

on gradient-echo images. This may be due to the very thin section thickness; however, improved visualization of cortical

bone

seems

inherent

three-dimensional

tears).

In summary, MR imaging can enable visualization of injuries to the biceps and triceps tendons, the UCL, loose bodies, osteophytes, and defects in subchondral bone. It is useful in the evaluation of soft-tissue masses and cysts, as it is elsewhere in the

T2-weighted

images

show

the

torn tendon edge to best advantage. Gradient-echo sequences, such as FISP, are helpful in evaluating bone surfaces, such as subchondral bone or the intraarticular part of the olecranon. Fragmentation of the olecranon, osseous

are usually

loose

bodies,

seen

and

to better

osteophytes

advantage

FISP

with

present only on radiographs obtained at sites that are suggestive of ligamentous avulsion with avulsion fracture, and the combination of radiography or tomography with MR imaging can help establish a reliable diagnosis. My results suggest that hypertrophic synovial tissue and trochlear chondromalacia are not well demonstrated with the MR imaging techniques described herein. In tendon and ligament injuries of the elbow, my results show that spinecho pulse sequences performed in several planes are most useful in the characterization of the severity of injury (eg, complete avulsions vs partial

gradient-echo

and

other

sequences.

Agreement

findand tendon injuries is encouraging, but further study is needed to determine the role of MR imaging in the evaluation of these patients. MR imaging could not depict hypertrophic synovium

ings

in

the

with

cases

that impinged dromalacia,

ered ing.

into

and

study,

tion malities

surgical

ligament

the

joint

or chon-

this must be considlimitation of MR imag-

a current Although

correlation

the

of

only

cases

with

surgical

were

included in this precise histopathologic correlawith observed MR signal abnorwas

musculoskeletal tic radiologist

not

has

possible.

system. The traditionally

diagnosplayed

August

1992

only a somewhat minor role in the workup of elbow injury. His or her armamentarium consisted of plain radiography, tomography, computed tomography, and elbow arthrography. Although these modalities are useful, the diagnosis of soft-tissue injury has remained largely a clinical one. Not infrequently, therapeutic decisions have been formulated by the orthopedic surgeon before the radiologist

interprets

the

Acknowledgments: The author acknowledges Marion Figueredo for writing and editorial assistance, and Bill Leon, RT, and Ken Nash, RT, for excellent technical assistance.

1.

2.

Lee JK, Yao L, Phelps pared

3.

4.

5.

6.

ligament

with arthroscopy

cuff lesions:

Murphy

BJ, Smith signal

complete

2

com-

and clinical

tests.

signal

1992; 182:

BF, An KN. contributions

joint.

Articular and ligato the stability of Am J Sports Med 1983; Ii:

patterns

tears

9.

Schwab GH, Bennott HS. Biomechanics

the rote of the medial 10.

11.

Sports Wilson Clusky

13.

i4.

ligament.

players:

a review

of 25 cases. Am

Med 1979; 7:72-80. FD, Andrews JR. Blackburn TA, McG. Valgus extension overload in

the pitching

at MR

collateral

Clin Orthop 1980; 146:42-52. Jobe FW, Newber G. Throwing injuries of the elbow. Clin Sports Med 1986; 5:621635. Indelicato PA,Jobe FW, Kertan RK, et at. Correctable elbow lesions in professional

baseball 12.

JB, Woods GW, Tullos of elbow instability:

elbow.

Am J Sports

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i(suppl):43-49. Bunnell DH, Fisher DA, Bassett LW, Gold RH, Ellman H. Elbow joint: normal anatomy on MR images. Radiology 1987; 165: 527-531. Marcus DS, Reicher MA, Kellerhouse LE. Achilles tendon injuries: the role of MR imaging. J Comput Assist Tomogr 1989; 13:480-485.

RL, Uribe JW, et at.

abnormalities

eral tibia and lateral

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Anterior

MR imaging

imaging. Radiology 1990; 177:817-823. Beltran J, Munchow AM, Khabiri H, et at. Ligaments of the lateral aspect of the ankle and sinus tarsi: an MR imaging study. Radiology 1990; 177:455-458. Zlatkin MB, Chao PC, Osterman AL, et al. Chronic wrist pain: evaluation with highresolution MR imaging. Radiology 1989; i73:723-729. Bone

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#{149} 529