DOI:10.2214/AJR.05.1086
AJR 2006; 187:1436-1441
© American Roentgen Ray Society
Using Sonography for the Early Detection of Elbow Injuries Among Young Baseball Players
Mikio Harada1,
Masatoshi Takahara1,
Junya Sasaki1,
Nariyuki Mura1,
Tomokazu Ito2 and
Toshihiko Ogino1
1 Department of Orthopaedic Surgery, Yamagata University School of Medicine,
Iida Nishi 2-2-2, Yamagata 990-9585, Japan.
2 Department of Orthopaedic Surgery, Saiseikai Yamagata Hospital, Yamagata,
Japan.
Received June 24, 2005;
accepted after revision November 11, 2005.
Address correspondence to M. Takahara
(mtakahar{at}med.id.yamagata-u.ac.jp).
Abstract
OBJECTIVE. The aim of this study was to determine the usefulness of
sonography for detecting elbow injuries among young baseball players.
SUBJECTS AND METHODS. One hundred fifty-three volunteers ranging in
age from 9 to 12 years and belonging to youth baseball teams participated.
Sonography of the elbow was performed in the field when baseball exercises
were being conducted. We analyzed the relationship between elbow pain and
sonographic abnormalities and the relationship between pitchers and
sonographic abnormalities.
RESULTS. Sonography showed that 33 subjects had medial epicondylar
fragmentation and two had early-stage osteochondritis dissecans of the
capitellum. In 25 subjects who agreed to further examination and treatment,
radiography confirmed the sonographic findings. All of the 23 subjects with
medial epicondylar fragmentation, who stopped throwing, obtained union of the
bone and returned to baseball. The two subjects with osteochondritis dissecans
of the capitellum underwent surgery before the osteochondral fragment became
loosened. Sonographic abnormalities correlated with episodes of elbow pain.
Pitchers statistically significantly had sonographic abnormalities.
CONCLUSION. Sonography in the field can provide an opportunity to
detect and treat elbow injuries before they become more advanced.
Keywords: elbow • injury • musculoskeletal imaging • pediatric imaging • screening • sonography • sports injuries
Introduction
Elbow injuries, including medial epicondylar fragmentation, osteochondritis
dissecans of the capitellum, and ulnar collateral ligament injury, are common
throwing injuries in athletes
[1]. Radiography and MRI have
proven effective for detecting early elbow abnormalities among young baseball
players
[2-13].
Recently, sonography, which is a safe, inexpensive, and portable type of
diagnostic imaging, has been used to assess elbow injuries
[3,
14-19].
Patients with symptoms of elbow injuries usually take some time to present
to a hospital, and consequently clinical examination tends to detect a great
number of advanced injuries, making treatment more difficult
[20]. We speculate that
players continue to play baseball because their elbow pain is not severe
enough to warrant medical attention
[3]. If examination of the
elbow could be performed in the field where athletes are training, it might be
possible to detect and treat elbow injuries before they become advanced.
Therefore, we attempted to detect elbow injuries among young baseball players
during training, using sonography. Players in whom abnormalities were found
were recommended to undergo further examination and treatment. The aim of this
study was to address the efficacy of sonography for detecting elbow injuries
among young baseball players.
Subjects and Methods
Institutional review board approval was obtained before the start of this
study, and informed consent was obtained from parents and coaches. One hundred
fifty-three volunteers participated in this study from 2001 to 2003. They
belonged to youth baseball teams in a league and ranged in age from 9 to 12
years (mean, 11.0 years). The duration of their active participation in
baseball was 0.2-5.0 years (mean, 2.1 years). The number of the subjects who
had played as a pitcher in the games was 34 (pitchers). The remaining 119
players (nonpitchers) had not played as a pitcher. All subjects were asked
whether they had ever had any episodes of elbow pain. The throwing and
nonthrowing elbows of each subject were examined in a room next to the field
where the subjects played baseball. Sonography of the medial and lateral
aspects of both elbows was performed by two of the authors, who are orthopedic
surgeons, using a 10-MHz annular array transducer (Aloka), as described in
previous articles [3,
14,
19]. A photograph depicting
the scanning technique of the medial aspect of the elbow is shown in
Figure 1.
Briefly, sonography of the medial aspect of the elbow showed the humeral
medial epicondyle, humeral trochlea, and ulnar collateral ligament (Figs.
2A and
3A). The growth plate of the
humeral medial epicondyle was visible on the coronal view (Figs.
2B,
2C, and
2D). On the lateral aspect of
the elbow, the sonograms showed the humeral capitellum, and the radial head
was visible on the sagittal view. The subchondral bone of the capitellum was
identified as a hyperechoic area, whereas its articular cartilage was
identified as a hypoechoic area (Figs.
3B,
3C, and
3D). We recommended
radiographic examination only to subjects who showed abnormal sonographic
findings. Twenty-five subjects agreed to undergo radiography within several
days after their examination in the field.
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Fig. 2A —Sonography and radiography of medial aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Imaging technique: transducer is placed on medial
aspect of elbow in 90° of flexion.
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Fig. 3A —Sonography and radiography of lateral aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Imaging technique: Transducer is placed on lateral
aspect of elbow in 0° of extension.
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Fig. 2B —Sonography and radiography of medial aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Diagram shows imaging plane of medial aspect of
elbow. Asterisk indicates medial epicondyle.
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Fig. 2C —Sonography and radiography of medial aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Sonogram (C) and corresponding diagram
(D) show medial aspect of elbow on nonthrowing side. Asterisk indicates
medial epicondyle; large arrow, growth plate between humeral medial epicondyle
and trochlea; small arrows, humeral trochlea; and arrowheads, ulnar collateral
ligament.
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Fig. 2D —Sonography and radiography of medial aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Sonogram (C) and corresponding diagram
(D) show medial aspect of elbow on nonthrowing side. Asterisk indicates
medial epicondyle; large arrow, growth plate between humeral medial epicondyle
and trochlea; small arrows, humeral trochlea; and arrowheads, ulnar collateral
ligament.
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Fig. 3B —Sonography and radiography of lateral aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Diagram shows imaging plane of lateral aspect of
elbow.
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Fig. 3C —Sonography and radiography of lateral aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Sonogram (C) and corresponding diagram
(D) of lateral aspect of elbow on nonthrowing side show humeral
capitellum (C) and radial head (R) from sagittal view. Subchondral bone of
capitellum is identified as hyperechoic area (arrows), whereas its
articular cartilage is identified as hypo-echoic area
(arrowheads).
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Fig. 3D —Sonography and radiography of lateral aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Sonogram (C) and corresponding diagram
(D) of lateral aspect of elbow on nonthrowing side show humeral
capitellum (C) and radial head (R) from sagittal view. Subchondral bone of
capitellum is identified as hyperechoic area (arrows), whereas its
articular cartilage is identified as hypo-echoic area
(arrowheads).
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We investigated sonographic abnormalities, such as medial epicondylar
fragmentation and osteochondritis dissecans of the capitellum, and then
statistically analyzed the relationship between elbow pain and these
sonographic abnormalities, and the relationship between pitchers and the
sonographic abnormalities using chi-square tests. For the subjects who
underwent radiography, two of the authors compared the radiographic findings
with the sonographic findings. In subjects with medial epicondylar
fragmentation, the periods from the examination to bone union and complete
return to baseball were investigated. Also, the size of the fragment in cases
of medial epicondylar fragmentation, shown on sonography and anteroposterior
radiography with the elbow flexed at 45°, was measured using a vernier
caliper. This measurement was performed by one of the authors. Statistical
analyses of the data were performed using a paired Student's t test.
Values were the mean ± SD, and differences at p < 0.05 were
considered to be significant.
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Fig. 2E —Sonography and radiography of medial aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Sonogram (E) and corresponding diagram
(F) show medial aspect of elbow on throwing side. Medial epicondylar
fragmentation (arrow) is evident as discontinuity of medial
epicondyle (asterisk).
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Fig. 2F —Sonography and radiography of medial aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Sonogram (E) and corresponding diagram
(F) show medial aspect of elbow on throwing side. Medial epicondylar
fragmentation (arrow) is evident as discontinuity of medial
epicondyle (asterisk).
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Fig. 2G —Sonography and radiography of medial aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Anteroposterior radiograph of elbow on throwing side
flexed at 45°. Asterisk indicates medial epicondyle.
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Fig. 2H —Sonography and radiography of medial aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Magnification of radiograph shows medial aspect of
elbow on throwing side. Asterisk indicates medial epicondyle. Extent of medial
epicondylar fragmentation (arrows) shown on radiography appears
smaller than that shown on sonography.
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Among 105 subjects examined in 2002, physical examination of the elbow,
including an examination for tenderness and a stress test, was also performed
by one of the authors. We analyzed the relationship between these physical
findings and the sonographic findings. The physicians performing the
sonography and those performing the physical examination were unaware of the
results of the other tests. Comparison between sonographic and physical
examinations was performed using chi-square tests, and differences at
p < 0.05 were considered to be significant.
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Fig. 3E —Sonography and radiography of lateral aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Sonogram (E) and corresponding diagram
(F) of lateral aspect of elbow on throwing side. Gap between fragment
(asterisk) and its base (arrows) in capitellum indicates
osteochondritis dissecans. R = radial head, C = capitellum.
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Fig. 3F —Sonography and radiography of lateral aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Sonogram (E) and corresponding diagram
(F) of lateral aspect of elbow on throwing side. Gap between fragment
(asterisk) and its base (arrows) in capitellum indicates
osteochondritis dissecans. R = radial head, C = capitellum.
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Fig. 3G —Sonography and radiography of lateral aspect of elbow in
12-year-old male baseball player. No player was symptomatic at time of
sonographic examination. Anteroposterior radiograph of elbow on throwing side
flexed at 45°. Early stage of osteochondritis dissecans of humeral
capitellum is shown as radiolucent region (arrows).
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Results
Among the 153 subjects, 62 experienced episodes of elbow pain while
throwing. The remaining 91 never experienced elbow pain. Sonography showed
that, in the throwing elbow, 35 subjects had sonographic abnormalities,
including medial epicondylar fragmentation in 33 (Figs.
2E and
2F) and osteochondritis
dissecans of the capitellum in two (Figs.
3E and
3F). Statistical analysis
showed that most subjects with sonographic abnormalities had experienced
episodes of elbow pain (Table
1). Sonography also showed that, in the nonthrowing elbow, no
subjects had sonographic abnormalities. Fourteen of 34 pitchers and 21 of 119
nonpitchers had sonographic abnormalities in the throwing elbow. Pitchers
statistically significantly had sonographic abnormalities.
Twenty-five subjects agreed to undergo radiography, which showed medial
epicondylar fragmentation in 23 (Figs.
2G and
2H) and osteochondritis
dissecans of the capitellum in two (Fig.
3G). Radiography confirmed the sonographic findings in all cases.
All 23 subjects with medial epicondylar fragmentation stopped throwing. They
all obtained radiographic union of the bone within 2-9 months (mean, 4.5
months) and made a complete return to baseball within 2-9 months (mean, 4.9
months) after the examination. One of the two subjects with osteochondritis
dissecans of the capitellum underwent fragment fixation. The other underwent
arthroscopic removal of a small osteochondral fragment after most of the
lesion had healed with conservative treatment. The remaining 10 subjects with
sonographic abnormalities did not undergo radiography or treatment because
their symptoms were not severe enough to warrant medical consultation.
The mean size of the fragment in cases of medial epicondylar fragmentation
was 4.0 ± 0.8 mm (range, 2.7-5.1 mm) on the sonograms and 3.4 ±
1.3 mm (range, 1.6-6.0 mm) on the radiographs. Although our statistical
analysis showed no significant difference in the fragment size between these
examinations (p = 0.26), sonography tended to show a greater degree
of medial epicondylar fragmentation than radiography.
Among the 105 subjects examined in 2002, 24 had tenderness of the medial
epicondyle, nine had elbow pain due to valgus stress, and 20 had medial
epicondylar fragmentation, as shown on sonography. The results of physical
examination correlated with the sonographic findings of medial epicondylar
fragmentation (Tables 2 and
3). However, tenderness of the
medial epicondyle was absent in 11 subjects with medial epicondylar
fragmentation as shown on sonography, and elbow pain due to valgus stress was
absent in 15 subjects with medial epicondylar fragmentation.
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TABLE 3: Relationship Between Elbow Pain at Valgus Stress Test and Medial
Epicondylar Fragmentation on Sonography
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Discussion
In our study, most subjects with sonographic abnormalities, including
medial epicondylar fragmentation and osteochondritis dissecans of the
capitellum, experienced episodes of elbow pain. However, according to the
results of our questionnaire, they never considered taking a break from
throwing or consulting a clinic. These results suggest that such elbow
injuries may be at an early stage and have a risk of becoming advanced if
individuals continue throwing.
In our study, 35 of the 153 subjects examined had sonographic
abnormalities, including medial epicondylar fragmentation and osteochondritis
dissecans of the capitellum. Findings obtained by radiography conformed
exactly to those obtained by sonography. These results suggest that sonography
can detect medial epicondylar fragmentation and osteochondritis dissecans of
the capitellum.
In our study, the findings of physical examination correlated significantly
with the findings of sonography. However, aspects of the physical examination,
including tenderness and stress test results, were not definitive for the
detection of medial epicondylar fragmentation, and false-negative findings
were obtained in some subjects. If sonography of the medial elbow had not been
performed, half of the present cases of medial epicondylar fragmentation would
not have been detected. These results indicate that sonography has a greater
ability to detect medial epicondylar fragmentation than physical examination
has.
For the early detection of osteochondritis dissecans of the capitellum,
Takahara et al. [3] performed
MRI and sonography and detected capitellar abnormalities in three of 44 young
baseball players. Those authors showed the early findings of osteochondritis
dissecans of the capitellum. Watanabe et al.
[16] performed sonography of
the elbows in 316 young baseball players and detected medial epicondyle
irregularity in 86 and capitellar abnormalities in three. Those authors also
suggested the possible effectiveness of sonography for detecting the early
changes of elbow injuries.
In our study, we visited the field where baseball exercises were being
performed, performed sonography, and detected elbow injuries among young
players. All 23 subjects with medial epicondylar fragmentation who stopped
throwing obtained bone union and returned to baseball without elbow pain. The
two cases of osteochondritis dissecans of the capitellum were also found
before the osteochondral fragment of the capitellum had become loosened. These
results suggest that our attempt to detect elbow injuries in the field was
successful and provided an opportunity to treat the injuries before they
became more advanced.
Sasaki et al. [19]
evaluated medial elbow laxity in college baseball players using sonography. In
our study, we could not assess the medial joint space. In the young subjects
whose humeral trochlea and coronoid process of the ulna are not sufficiently
ossified, it is impossible to identify the joint space using sonography. We
did not recommend radiography to subjects who did not have any sonographic
abnormalities. Therefore, the sensitivity of sonography could not be
determined in this study; however, we speculate that the sensitivity would be
fairly high because sonography had a higher sensitivity than physical
examination and tended to show a greater degree of the fragment than
radiography.
In summary, sonography in the field makes it possible to detect medial
epicondylar fragmentation and osteochondritis dissecans of the capitellum.
These elbow injuries can be detected even in their asymptomatic stage. Our
attempt to detect these injuries in the field was successful and provided an
opportunity to treat the injuries before they became more advanced. We
conclude that sonography of the elbow in the field is useful for early
detection of elbow injuries among young baseball players.
Acknowledgments
We thank the coaches and parents of the youth baseball teams for their
assistance and support in this study.
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Abstract
Introduction
