Costal Cartilage Injury in Acute Trauma

Costal Cartilage Injury in Acute Trauma
Matthew O’Brien MD, David Spizarny, MD, Daniel T Myers, MD
Department of Radiology, Henry Ford Health System, Detroit, Michigan
Abstract
Characterization and Trauma Score
The costal cartilages, (CC’s,) which can be indicative of sex, bone age, and underlying
systemic disease processes, 1-5 often experience the large, sudden forces of acute body
trauma including that of motor vehicle collisions. Despite descriptions of the imaging
appearances on Radiographs, Ultrasound, and Magnetic Resonance Imaging, 6,7 there is a
paucity of literature describing CC injuries on Computed Tomography. Our primary intent is
to review and characterize the spectrum of CC injuries based on a ten-year retrospective
review of blunt trauma related body CT studies performed at our institution between 2003
and 2013 in which such injuries were prospectively identified. Secondly we propose a
simple schema for characterization and classification of costal cartilage injuries based on our
review. We then relate that classification system to the American Association for the Surgery
of Trauma (AAST) Chest Wall Trauma Score. Finally we demonstrate some characteristic
imaging appearances of costal cartilage injuries, and related injuries and complications.
We advocate for a simple classification scheme based on type of CC disruption, (fracture,
separation,) location, (costochondral, midchondral, costosternal or costomanubrial,) percent
displacement in terms of shaft width, and separation distance.
Rib fractures play a major role in assessment of the Chest Wall Trauma Score. A summary of
this impact is in the table below:
Rib Fracture Impact on Chest Wall Trauma Score
Grade
I
II
III
Rib Fractures
≥ 3 closed
< 3 segment
unilateral flail chest
V
≥ 3 segment
unilateral flail chest
Bilateral flail chest
We propose that costal cartilage injuries be considered similar to rib fractures in the chest wall
trauma score as in our experience they appear to impart similar risks and the two often coexist.
c.
d.
18
16
60
14
Number of Injuries
Percent of Injuries
50
40
30
20
12
Rib Fractures
10
CI's
8
6
4
10
2
0
CCh
MC
CS/CM
Type of Injury
0
1
2
3
4
5
6
7
8
9
10
11
12
Rib Number
Figure 2.
Most injuries are costochondral, (CCh,)
followed by midchondral, (MC,) then
costosternal and costomanubrial, (CS/CM.)
e.
f.
Figure 3.
The distribution of injuries roughly follows the distribution of rib
fractures in the same group of patients. Notably, the frequency of both
cartilaginous injuries (CI’s,) and rib fractures by location is directly
correlated with rib length; increasing in frequency from ribs 1-7, and
decreasing from 7-12.
Figure 5.
A right costochondral separation, (a) associated with trauma. After a coughing episode, a follow up study for chest wall swelling
reveals a large right anterior lung herniation, (b, c, d) into the chest wall soft tissues through the cartilaginous defect. A
postoperative study after emergent intervention (e) demonstrates reduction of the herniated lung, with internal and external
fixation of the chest wall.
• CC injuries are uncommon injuries and, in our experience, may easily be overlooked.
• CC trauma commonly occurs in three locations:
1. The CC attachment to the ossified rib end, or “costochondral junction,”
2. In the mid-cartilage, or “midchondral” location, or
3. At the costosternal/costomanubrial attachment.
• Potential complications mimic those of rib fractures, and include:
• Associated rib fractures and other costal cartilage injuries
• Mediastinal hematomas
• Sternal, manubrial, clavicular, and pelvic fractures
• Pneumothorax and hemothorax
• Chest wall lacerations and subcutaneous emphysema
• Greater awareness of spectrum of injuries and their appearances is intended to lead to
greater recognition of this traumatic injury.
Figure 4.
A Costochondral fracture of the 6th rib, (a) with associated clavicular fracture, (b) indicating high energy trauma.
Displaced midchondral separations are seen in noncalcified, (c) and calcified, (d) cartilages.
A mildly displaced calcified costomanubrial fracture is seen in a patient status post MVC, (e). Note the well-defined
hypoattenuation through the noncalcified portion of the cartilage. In another patient, multiple contiguous midchondral cartilage
fractures (f) are significantly displaced on this coronal view.
Associated Injuries / Complications
Figure 2: Distribution of Injuries
e.
Learning Points
Methods
Figure 1: Distribution by Location
d.
b.
Figure 1.
Diagrammatic representation
of the costal cartilages,
(blue,) in the thoracic cage.
Adapted from Gray’s
Anatomy, 20th edition, 1918.
Common Sites and Types of CC Injury
c.
Pictorial Review of injuries
a.
After approval by our Institutional Review Board (IRB), a retrospective review of
radiology reports and CT images from the radiology archive for the prospective diagnosis of
costochondral injury in patients undergoing CT scan of the thorax for trauma was performed.
We used a medical search engine (Softek Illuminate, Prairie Village, KS, USA) to search a
10 year time frame, (January 2003–December 2013,) in patients 18 years of age or greater.
Data search utilized key phrases including “costal”, “chondral”, “cartilage” and
“costochondral,” resulting in 44 cases. Each case was reviewed by a Radiologist with 15
years post fellowship experience in trauma imaging to confirm the presence of costal
cartilage injury. Review of the electronic medical record was conducted to determine
associated injuries and complications.
b.
*Increase one grade for bilaterality
Anatomy of Ribs and Costal Cartilages
• Costal Cartilages are the anterior-most portions of the 7 true and 3
false costal rings.
• True ribs are individually attached to the sternum via CC’s.
• False ribs share a cartilaginous attachment to the sternum.
• Floating ribs do not contact the sternum.
• Ribs 1 and 2 are uniformly thick and quite dense, with short CC’s.
• Ribs increase in length from 1-7, then decrease from 7-12.
• CC’s originate from the same mesenchymal sclerotomes as their
corresponding ribs. 8
• Each rib and CC form a ring, with most plasticity imparted by
the CC’s. 9
• CC’s vascularize and calcify or ossify with age in various
patterns which vary somewhat predictably by sex, age and
race. 1-5, 10, 11
• Calcification is present in most 20-80 year old patients, begins
in the third decade, and may decrease plasticity. 1, 12, 13, 14
< 3 closed
IV
a.
Most associated injuries observed in our case series were also associated with rib fractures.
The frequency of such injuries included rib fractures, (seen in 50% of cases,) additional CC
injuries, (48%,) mediastinal hematomas, (32%,) sternal/manubrial fractures, (22%,) chest wall
hematoms, (18%,) pneumothoraces, (20%,) hemothoraces, (9%,) chest wall lacerations, (9%,) and
clavicular fractures, (7%.)
In a few unique cases, there were late complications as well, as in one particular case in which
multiple small chondral separations, (figure 5,) when combined with contralateral rib fractures,
functioned as a flail segment and resulted in a dramatic lung herniation which required surgical
closure.
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