AJR 2001; 176:429-432
© American Roentgen Ray Society
Costal Cartilage Fractures as Revealed on CT and Sonography
Jacques Malghem1,
Bruno C. Vande Berg,
Frederic E. Lecouvet and
Baudouin E. Maldague
1
All authors: Department of Radiology, University of Louvain, St. Luc
University Hospital, Hippocrate Ave., 10, B-1200 Brussels, Belgium.
Received May 11, 2000;
accepted after revision July 12, 2000.
Address correspondence to J. Malghem.
Abstract
OBJECTIVE. We describe the CT and sonographic appearance of 15
costal cartilage fractures observed in eight patients.
CONCLUSION. On CT, fracture was seen as a low-density area through
the costal cartilage, with surrounding calcifications present near old
fractures, and gas density within the cleft in some cases. On sonography,
cartilage fracture appeared as an interruption of the smooth anterior aspect
of the cartilage.
Introduction
Chest injuries are frequent. Bony rib fractures are usually revealed on
radiographs [1], but
radiography cannot show fractures occurring in costal cartilages, except for
densely calcified cartilages
[1].
Costal cartilage fractures have rarely been reported in the literature
[2,
3]. We report a series of eight
patients presenting with 15 costal cartilage fractures diagnosed on CT in all
patients and on sonography in three patients.
Materials and Methods
Fifteen costal cartilage fractures were diagnosed in eight patients (two
women and six men), who were 19-52 years old (mean age, 32 years; median age,
27.5 years) between 1989 and 1999. Four patients were initially examined at
our institution, and four were referred for advice or additional examination.
Five patients had a definite history of recent chest wall injury. In the other
three patients, practice of contact sports was noted in two, and a fall 3
months earlier in one.
CT or sonography was performed because of severe posttraumatic parasternal
pain unexplained by radiographic findings, or because of a painful parasternal
mass with clinical suspicion of tumor in patients without obvious recent
trauma. In one patient, a surgical biopsy had been performed that showed the
presence of chondroid tissue with atypical chondrocytes, raising the
possibility of a malignant chondroitic tumor. In another patient, a needle
biopsy disclosed aspecific hemorrhagic material.
Radiography and CT were available in all eight patients, and sonography in
three.
Results
Six fractures involved the first ribs; two, the second, third, and sixth
ribs; and one, the fourth, seventh, and eighth ribs
(Fig. 1). There were six right-
and nine left-sided fractures. The fractures involved the chondrosternal
(three lesions) or the chondrocostal (three lesions) junction for the first
rib lesions and the middle region of the costal cartilage for the other
locations. In three patients, fractures of bony ribs were also seen. Four
patients had multiple contiguous cartilage fractures (two patients with two
lesions, one patient with three, and one patient with four).
No fractures were seen on radiography. The diagnosis of costal cartilage
fracture was established using CT in all 15 lesions. CT images consistently
revealed a focal discontinuity of the costal cartilage, with displacement in
five (33%) of 15 lesions (Fig.
2A). Swelling of the neighboring soft tissues was seen in four
lesions. Focal surrounding calcifications were visible near three fractures on
CT scans obtained several weeks after the presumed causal trauma (Figs.
3A,3B,3C,3D,3E
and
4A,4B).
In four fractures involving the chondrosternal or chondrocostal junction, fine
linear lucencies with a gas density were present in the cartilaginous cleft
(Fig. 5A).

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Fig. 2A. 26-year-old man with multiple rib fractures after motor
vehicle collision. CT scan reveals interruption (arrows) with break
in continuity of third costal cartilage. Patient also had multiple other bony
rib and costal cartilage fractures (not shown).
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Fig. 3A. 28-year-old man with painful left parasternal lump for 6
months. Patient reported no traumatic history but was drug addict and engaged
in contact sports. Bone scan shows discrete area of increased uptake in left
parasternal area (arrow) at level of lump, and several other intense
foci in extremities of subjacent ribs corresponding to fractures.
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Fig. 3B. 28-year-old man with painful left parasternal lump for 6
months. Patient reported no traumatic history but was drug addict and engaged
in contact sports. Transverse CT (B) and sagittal oblique multiplanar
reformatted CT (C) scans perpendicular to costal cartilage of left
sixth rib show heterogeneous focal swelling, with peripheral
calcifications.
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Fig. 3C. 28-year-old man with painful left parasternal lump for 6
months. Patient reported no traumatic history but was drug addict and engaged
in contact sports. Transverse CT (B) and sagittal oblique multiplanar
reformatted CT (C) scans perpendicular to costal cartilage of left
sixth rib show heterogeneous focal swelling, with peripheral
calcifications.
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Fig. 3D. 28-year-old man with painful left parasternal lump for 6
months. Patient reported no traumatic history but was drug addict and engaged
in contact sports. Curved frontal multiplanar reformatted (D) and
maximum-intensity-projection (E) images from sets of CT slices of
anterior chest wall show that focal hypodensity and peripheral calcifications
correspond to transverse area perpendicular to costal cartilage.
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Fig. 3E. 28-year-old man with painful left parasternal lump for 6
months. Patient reported no traumatic history but was drug addict and engaged
in contact sports. Curved frontal multiplanar reformatted (D) and
maximum-intensity-projection (E) images from sets of CT slices of
anterior chest wall show that focal hypodensity and peripheral calcifications
correspond to transverse area perpendicular to costal cartilage.
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Fig. 4A. 46-year-old man with history of overlooked thoracic trauma
that occurred 3 months earlier during stay in intensive care unit. CT scans
show swelling of soft tissue surrounding irregular costal cartilage with focal
interruptions (thick arrow, A) and typical fracture
angulations (thick arrow, B). Note peripheral calcifications
(thin arrows).
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Fig. 4B. 46-year-old man with history of overlooked thoracic trauma
that occurred 3 months earlier during stay in intensive care unit. CT scans
show swelling of soft tissue surrounding irregular costal cartilage with focal
interruptions (thick arrow, A) and typical fracture
angulations (thick arrow, B). Note peripheral calcifications
(thin arrows).
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Fig. 5A. 19-year-old man who experienced sudden onset of left
parasternal pain during gymnastic training on parallel bars. S = sternum. CT
scan shows thin band of gas density (thick arrow) within gap between
cartilage of first left rib (thin arrow) and sternum.
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In the three patients who underwent sonography, the abnormalities consisted
of a discontinuity in the thin echogenic line corresponding to the anterior
aspect of the hypoechogenic cartilage in all six lesions, with a step-off in
two lesions (Fig. 2B) and a
small hyperechogenic area perpendicular to the cartilage surface in one
lesion, corresponding to the gas density observed on the CT image of the same
lesion (Fig. 5B).

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Fig. 2B. 26-year-old man with multiple rib fractures after motor
vehicle collision. Sonogram of third rib shows interruption and displacement
of hyperechogenic line, corresponding to ventral aspect of costal cartilage
(arrows).
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Fig. 5B. 19-year-old man who experienced sudden onset of left
parasternal pain during gymnastic training on parallel bars. S = sternum.
Sonogram (dual image) of same region as A shows small hyperechogenic
area (thick arrow) corresponding to gas accumulation between
hypoechogenic cartilage (thin arrow) and hyperechogenic line
delineating anterior aspect of sternum.
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Discussion
Costal cartilage fractures are not radiographically recognizable unless the
fracture involves a strongly calcified cartilage. Generally, costal cartilages
are not visible on radiographs, with the exception of irregular ossification
foci that appear during adulthood
[4]. However, costal cartilages
are easily recognizable with CT or sonography. On CT, cartilage density is
relatively uniform (70-120 H) and of higher density than that of the overlying
muscles and fat, but less dense than calcium
[5]. On sonography, the
cartilage is less echogenic than the adjacent muscle and is delineated by a
thin echogenic anterior margin. Cartilages are oriented along a horizontal or
oblique axis. They appear as a round, ovoid, or ribbonlike pattern depending
on the perpendicular or parallel orientation of the imaging plane with respect
to the cartilage axis. Sonography, usually available in every emergency
department, offers the advantage of easy multiplanar scanning capability,
which is also obtained with multiplanar reformatted images from thin CT slices
(Fig.
3A,3B,3C,3D,3E).
Fractures of costal cartilages are not often described in the literature.
Occasional illustrations are included in books or reviews discussing chest
injuries or costal lesions [4,
6,
7]. We found three reports in
the literature describing a total of 15 costal cartilage fractures diagnosed
with sonography [2,
3] or CT
[8].
In our series, fractures were recognized by visualizing focal interruption
in the relatively high costal cartilage density on CT images, or in the linear
echogenic anterior margin of the hypoechogenic cartilages on sonography. A
significant displacement of the adjacent segments was evident in one third of
the lesions and soft-tissue swelling on CT images in four of the 15 lesions.
Two additional abnormalities were observed. First, calcifications surrounding
the fracture sites were seen in three lesions examined several weeks after the
presumed causal trauma. Milgram
[7] also observed focal
calcifications near a costal cartilage on a histopathologic specimen from a
patient engaged in karate who had noticed a lump on his chest cage for several
months. Second, a thin area with gas density within the cartilage cleft was
seen in four of the six lesions involving the chondrocostal or chondrosternal
junctions. This accumulation of gas is probably the result of a vacuum
phenomenon in the fracture cleft.
Costal cartilage fractures probably occur more frequently than is currently
recognized because of underdiagnosis. Flail chest fractures may involve the
chondrocostal or chondrosternal junctions, which cannot be identified
radiographically [1]. In a
sonographic study of patients with suspected rib fracture, Griffith et al.
[3] found that 11% of all
fractures were located in the costal cartilage or at the chondrocostal
junction.
In our patients, none of the lesions were diagnosed using radiography. CT
or sonography was performed either because of unexplained considerable local
acute posttraumatic pain, or because of a chronic painful lump without an
obvious origin. Chronic symptoms may be caused by the inability of
chondrocytes to respond effectively to cartilage fracture
[9], contrary to bone cells
that generate a neoformative process generally leading to consolidation of
bony rib fractures within several weeks. When a chronic fracture of the
cartilage is not recognized, the lesion may be misdiagnosed. Histologic
analysis of the biopsy can reveal chondroid tissue with atypical cells
suggestive of a malignant tumor, as we found in a 46-year-old man with a
painful lump in the anterior thoracic chest wall 3 months after an overlooked
thoracic trauma (Fig.
4A,4B).
Cartilage fractures in our series were located at the chondrocostal or
chondrosternal junction for the first ribs, and the middle region of the other
costal cartilages. Most lesions were observed in patients who were relatively
young (median age, 27.5 years) and male (6/8). A larger series is needed to
determine whether this sex, age, and topographic distribution reflects the
true prevalence of these fractures that could result from peculiar mechanical
characteristics (i.e., increased risk for cartilage fractures, especially when
the bony ribs are strong in young men).
Differential diagnosis includes other painful lesions of the costal
cartilage, such as costochondritis and Tietze's and Cyriax's syndromes.
Costochondritis and Tietze's syndromes are ill-defined disorders characterized
by pain originating from the chondrocostal articulations of the second to
fifth ribs, with local swelling in Tietze's syndrome. Pathogenesis is unclear
and could be of traumatic origin. Diagnosis of Tietze's syndrome is generally
based on clinical findings, although cartilage swelling may be visible on CT
[5] or sonography
[10]. However, no abnormal
findings were found either on CT or sonography in another series
[11]. Cyriax's syndrome
("slipping rib syndrome") is a disorder affecting the anterior
extremity of the eighth, ninth, and 10th ribs, which articulate with the
superjacent ribs and not with the sternum. This syndrome, encountered
especially in women around the age of 50 years, seems to be a result of
posttraumatic subluxation of these costocostal articulations. The
diagnosis is also based on clinical findings
[12]. When the dominant
symptom is a focal mass, tumoral or infectious lesions of the chest wall must
be also considered [4].
Chondral fracture with soft-tissue swelling can be differentiated from these
entities by visualization of the fracture line (the curved multiplanar
reformatted CT images are especially helpful in this evaluation), a step-off
deformity, and contained gas within the cartilage cleft, which is present in
some cases.
In conclusion, our observations show that CT and sonography enable
recognition of costal cartilage fractures, a diagnosis often overlooked on
radiography. A search for such lesions using CT or sonography is indicated in
cases of severe acute posttraumatic parasternal pain, or painful parasternal
mass without obvious recent trauma. It is difficult to say whether the costal
cartilage fractures, infrequently reported in the literature, are truly
exceptional or if they are just underdiagnosed.
Acknowledgments
We thank J. L. Doyen, C. Villers, and C. Lebon for referring patients; P.
Michel and H. Noël for the histologic analysis
of the biopsied specimens; and Françoise
Martin, Martine Millecan, Jocelyne Burion, and Anne Smith for editorial
assistance.
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