Abstract Characterization and Trauma Score

Associated Injuries / Complications

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:

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.

Anatomy of Ribs and Costal Cartilages Pictorial Review of injuries

Learning Points

• 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

Common Sites and Types of CC Injury References1. Ontell FK, Moore EH, Shepard JA, Shelton DK. The costal cartilages in health and disease. Radiographics. 1997;17(3):571-7.

2. Moskovitch G, Dedouit F, Braga J, Rougé D, Rousseau H, Telmon N. Multislice computed tomography of the first rib: a useful technique for bone age assessment. J Forensic Sci. 2010;55(4):865-70.

3. Navani S, Shah JR, Levy PS. Determination of sex by costal cartilage calcification. Am J Roentgenol Radium Ther Nucl Med. 1970;108(4):771-4.

4. Rao NG, Pai LM. Costal cartilage calcification pattern--a clue for establishing sex identity. Forensic Sci Int. 1988;38(3-4):193-202.

5. Rejtarová O, Slízová D, Smoranc P, Rejtar P, Bukac J. Costal cartilages--a clue for determination of sex. Biomed Pap Med Fac UnivPalacky Olomouc Czech Repub. 2004;148(2):241-3.

6. Griffith JF, Rainer TH, Ching AS, Law KL, Cocks RA, Metreweli C. Sonography compared with radiography in revealing acute rib fracture. AJR Am J Roentgenol. 1999;173(6):1603-9.

7. Subhas N, Kline MJ, Moskal MJ, White LM, Recht MP. MRI evaluation of costal cartilage injuries. AJR Am J Roentgenol. 2008;191(1):129-32.

8. Huang R, Zhi Q, Schmidt C, Wilting J, Brand-saberi B, Christ B. Sclerotomal origin of the ribs. Development. 2000;127(3):527-32.

9. Lau A, Oyen ML, Kent RW, Murakami D, Torigaki T. Indentation stiffness of aging human costal cartilage. Acta Biomater. 2008;4(1):97-103.

10. Kampen WU, Claassen H, Kirsch T. Mineralization and osteogenesis in the human first rib cartilage. Ann Anat. 1995;177(2):171-7.

11. Sunwoo WS, Choi HG, Kim DW, Jin HR. Characteristics of rib cartilage calcification in Asian patients. JAMA Facial Plast Surg. 2014;16(2):102-6.

12. Lau AG, Kindig MW, Kent RW. Morphology, distribution, mineral density and volume fraction of human calcified costal cartilage. ActaBiomater. 2011;7(3):1202-9.

13. Forman JL, Kent RW. The effect of calcification on the structural mechanics of the costal cartilage. Comput Methods Biomech Biomed Engin. 2014;17(2):94-107.

14. Lucet L, Le loët X, Ménard JF, et al. Computed tomography of the normal sternoclavicular joint. Skeletal Radiol. 1996;25(3):237-41.

15. Graeber GM, Nazim M. The anatomy of the ribs and the sternum and their relationship to chest wall structure and function. Thorac SurgClin. 2007;17(4):473-89, vi.

• 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.

Costal Cartilage Injury in Acute TraumaMatthew O’Brien MD, David Spizarny, MD, Daniel T Myers, MD

Department of Radiology, Henry Ford Health System, Detroit, Michigan

0

10

20

30

40

50

60

CCh MC CS/CM

Per

cen

t o

f In

juri

es

Type of Injury

Figure 1: Distribution by Location

0

2

4

6

8

10

12

14

16

18

1 2 3 4 5 6 7 8 9 10 11 12

Nu

mb

er o

f In

juri

es

Rib Number

Figure 2: Distribution of Injuries

Rib Fractures

CI's

Grade I II III IV V

Rib Fractures < 3 closed ≥ 3 closed < 3 segment

unilateral flail chest

≥ 3 segment

unilateral flail chest

Bilateral flail chest

*Increase one grade for bilaterality

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.

a.

e.

b. c.

d.

MethodsAfter 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.

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 2.

Most injuries are costochondral, (CCh,)

followed by midchondral, (MC,) then

costosternal and costomanubrial, (CS/CM.)

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.

a. b.

c.

e. f.

d.

Rib Fracture Impact on Chest Wall Trauma Score

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.

Figure 1.

Diagrammatic representation

of the costal cartilages,

(blue,) in the thoracic cage.

Adapted from Gray’s

Anatomy, 20th edition, 1918.