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1
Department of Radiology, Health South Medical Center, 1201 11th Ave. S.,
Birmingham, AL 32505, and Advanced Imaging Associates of Alabama, P.C., P.O.
Box 660552, Birmingham, AL 35266.
2
Insall Scott Kelly Institute for Orthopaedics and Sports Medicine, 170 E. End
Ave. at 87th St., New York, NY 10016.
3
American Sports Medicine Institute and the Alabama Sports Medicine and
Orthopaedic Center, 1201 11th Ave. S., Birmingham, AL 35205.
Received December 14, 1999;
accepted after revision February 28, 2000.
Address correspondence to S. A. Mulligan.
Abstract
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MATERIALS AND METHODS. Retrospective radiographic review of 710 patients examined for elbow pain yielded 42 individuals (age range, 16-38 years) with heterotopic calcification in the ulnar collateral ligament. Radiographic and MR imaging findings were compared with surgical findings.
RESULTS. Fifty-one heterotopic calcifications were identified in 42 patients; nine patients had two sites of heterotopic calcification. Average initial calcification size in the craniocaudal dimension was 4 mm (range, 1-12 mm) and in the transverse dimension was 1 mm (range, 1-4 mm). Five of 42 patients had enlargement of the calcification on follow-up radiography. The largest heterotopic calcification that was not visualized on MR imaging measured 5 x 4 mm in craniocaudal and transverse dimensions. Of 34 patients with heterotopic calcification who underwent surgery, 26 patients (76%) had either partial or complete tears of the ulnar collateral ligament.
CONCLUSION. Heterotopic calcification in the ulnar collateral ligament may be associated with partial or complete tears. The MR imaging detection of heterotopic calcification is less sensitive than that of radiography of the elbow.
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Radiographs of the elbow were evaluated to determine the number and location of heterotopic calcifications. Anteroposterior, lateral, and bilateral oblique elbow radiographs were reviewed, and the size of each heterotopic calcification was measured to the nearest millimeter. If follow-up radiographs were available, the size and number of heterotopic calcifications seen at follow-up were documented.
Elbow MR imaging with intraarticular contrast material was performed after intraarticular injection of saline using a method previously described [9]. MR imaging was performed with a 1.5-T scanner (Signa; General Electric Medical Systems, Milwaukee, WI). Coronal T1-weighted images (TR/TE, 420/20; matrix, 256 x 128; signals averaged, four; section thickness, 3 mm; intersection gap, 1 mm; field of view, 16 cm) and multiplanar coronal gradient-echo images (450/12; flip angle, 20°; matrix, 256 x 128; signals acquired, one; section thickness, 3 mm; intersection gap, 1 mm; field of view, 16 cm) were obtained (Fig. 1A,1B). A general purpose 5-inch (12.7-cm) coil was used for each image.
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MR imaging examinations were evaluated by two radiologists to determine the visibility and appearance of heterotopic calcifications and the integrity of the ulnar collateral ligament. The radiologists reviewing the MR images knew of the presence of heterotopic calcifications; however, they were blinded to the size, number, and location of calcifications.
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All the patients with heterotopic calcification were athletes. Most (35/42) patients with heterotopic calcification were pitchers: 19 professional, 12 college, and four high school. The remaining patients included two professional baseball fielders, two college baseball fielders, one high school football lineman, one high school tennis player, and one recreational racquetball player. Thirty-nine (93%) of 42 patients with heterotopic calcification were throwing athletes. Of 497 throwing athletes whose radiographs were reviewed, 39 (7.8%) had heterotopic calcifications in the ulnar collateral ligament.
Fifty-one heterotopic calcifications were identified in 42 patients; nine patients had two heterotopic calcifications. All calcifications were smoothly marginated. The calcification size was measured on radiographs. The initial average craniocaudal dimension was 4 mm (range, 1-12 mm), and the average transverse dimension was 1 mm (range, 1-4 mm). Two patients had confluent ossification of the distal ulnar collateral ligament in addition to heterotopic calcification (Fig. 2A,2B). Five (12%) of 42 patients had an increase in size of the calcification on radiographic follow-up, and the average time to final measurement was 28 months (range, 9-91 months). The final average craniocaudal dimension was 5 mm (range, 1-13 mm), and the final average transverse dimension was 2 mm (range, 1-7 mm).
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Thirty-four of 42 patients underwent MR imaging of the elbow at the time of their examination for elbow pain. Twenty-seven patients underwent contrast-enhanced MR imaging of the elbow at our institution. Seven patients underwent MR imaging examinations outside our institution; these examinations were performed without intraarticular contrast material. One outside MR imaging study that was unavailable for review reported a complete tear of the ulnar collateral ligament that was confirmed at surgery. Five patients had multiple MR imaging studies: four patients had two MR imaging examinations, and one patient had five MR imaging studies over 7 years. Forty-one MR imaging examinations for 33 patients were reviewed.
Of the 33 patients with MR imaging studies available for review, heterotopic calcification was visualized in the ulnar collateral ligament in 24 patients; nine patients had MR imaging examinations that failed to reveal heterotopic calcification that was present on radiography. The largest heterotopic calcification that was not visualized on MR imaging was 5 mm in craniocaudal dimension and 4 mm in transverse dimension. The sensitivity of MR imaging of the elbow for the depiction of heterotopic calcification in the ulnar collateral ligament was 73% (24/33 patients).
Surgical findings were available for comparison in 34 of 42 patients with heterotopic calcification; eight patients did not undergo surgery. At surgery, the ulnar collateral ligament was intact in eight patients, partially torn in six, and completely torn in 20. Therefore, of 34 patients with heterotopic calcification who underwent surgery, 26 (76%) had either partial or complete tears of the ulnar collateral ligament.
Of 34 patients who underwent surgery, 30 had MR imaging performed before surgery. The time between MR imaging and surgery averaged 3 days (range, 1-185 days). In seven of seven patients, an intact ulnar collateral ligament on MR imaging correlated with findings at surgery. In five of six patients, a partial tear of the ulnar collateral ligament on MR imaging correlated with findings at surgery (Fig. 3A,3B); one patient had a partial tear of the ulnar collateral ligament at surgery that was interpreted as normal on MR imaging. A complete ulnar collateral ligament tear diagnosed on MR imaging correlated with findings at surgery in 14 of 17 patients (Fig. 4A,4B). MR imaging revealed partial tears in three patients who had complete tears of the ulnar collateral ligament at surgery.
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The sensitivity of MR imaging was 96% for all tears of the ulnar collateral ligament (22/23 tears) and 83% (5/6 tears) and 82% (14/17 tears), respectively, for partial and complete tears. We noted no false-positive MR imaging interpretations. The positive predictive value of MR imaging of the elbow for tears of the ulnar collateral ligament was 100%, and the negative predictive value was 88%.
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A positive association between heterotopic calcification and partial or complete tears of the ulnar collateral ligament is revealed in our series of patients. Of 34 patients with ulnar collateral ligament heterotopic calcification who underwent surgery, 26 (76%) had either partial or complete tears of the ulnar collateral ligament at surgery. However, the retrospective design of this study may artificially increase the number of patients with surgical intervention and ulnar collateral ligament tears because the patient series was formed from individuals examined for elbow pain by an orthopedic surgeon. The origin of heterotopic calcification may have resulted from recurrent stress, avulsion injury of the medial epicondyle, or both.
Other causes of calcification or osseous deposition in the elbow should be differentiated from ulnar collateral ligament heterotopic calcification. Intraarticular loose bodies are surrounded by intraarticular contrast material, whereas ulnar collateral ligament heterotopic calcification is identified in an extraarticular location. Avulsion fractures of the sublime tubercle of the ulna result in bone density adjacent to the sublime tubercle [12]. Bone fragments of avulsion fractures of the sublime tubercle have irregular margins contiguous to the donor site of origin in the proximal ulna. Ulnar collateral ligament heterotopic calcifications are smoothly marginated without evidence of ulnar avulsion. In patients with avulsion fractures of the sublime tubercle, the ulnar collateral ligament is intact.
Medial elbow pain is a common complaint of throwing athletes, with multiple causes that include medial epicondylitis, common flexor tendinosis, partial or complete tears of the ulnar collateral ligament, intraarticular loose bodies, and fracture. Heterotopic calcification in the ulnar collateral ligament may be associated with ulnar collateral ligament injury and tear. However, ulnar collateral ligament heterotopic calcification may be difficult to visualize on MR imaging; our series revealed an overlooked heterotopic calcification of the ulnar collateral ligament measuring 5 x 4 mm. The decreased sensitivity of MR imaging in the detection of heterotopic calcification in the ulnar collateral ligament may result from tissue contrast similarities and volume-averaging of the calcification with adjacent soft-tissue structures. The difficulty detecting heterotopic calcifications of the ulnar collateral ligament on MR imaging of the elbow is similar to the problem of diagnosing calcific tendinosis of the shoulder on MR imaging. Comparison of MR imaging of the elbow with radiography is required in the detection of heterotopic calcification in the ulnar collateral ligament.
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