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 We advocate for a simple classification scheme based on type of CC disruption, (fracture, a. b. c. systemic disease processes, 1-5 often experience the large, sudden forces of acute body separation,) location, (costochondral, midchondral, costosternal or costomanubrial,) percent trauma including that of motor vehicle collisions. Despite descriptions of the imaging displacement in terms of shaft width, and separation distance. appearances on Radiographs, Ultrasound, and Magnetic Resonance Imaging, 6,7 there is a fractures play a major role in assessment of the Chest Wall Trauma Score. A summary of paucity of literature describing CC injuries on Computed Tomography. Our primary intent is this impact is in the table below: 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 Rib Fracture Impact on Chest Wall Trauma Score Grade I II III IV V and 2013 in which such injuries were prospectively identified. Secondly we propose a Rib Fractures < 3 closed ≥ 3 closed < 3 segment ≥ 3 segment Bilateral flail chest simple schema for characterization and classification of costal cartilage injuries based on our unilateral unilateral flail chest review. We then relate that classification system to the American Association for the Surgery *Increase one grade for bilaterality of Trauma (AAST) Chest Wall Trauma Score. Finally we demonstrate some characteristic We propose that costal cartilage injuries be considered similar to rib fractures in the chest wall imaging appearances of costal cartilage injuries, and related injuries and complications. trauma score as in our experience they appear to impart similar risks and the two often coexist. d. e.

Anatomy of and Costal Cartilages Pictorial Review of injuries • Costal Cartilages are the anterior-most portions of the 7 true and 3 false costal rings. a. b. • True ribs are individually attached to the 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 Figure 5. corresponding ribs. 8 A right costochondral separation, (a) associated with trauma. After a coughing episode, a follow up study for chest wall swelling • Each rib and CC form a ring, with most plasticity imparted by reveals a large right anterior herniation, (b, c, d) into the chest wall soft tissues through the cartilaginous defect. A 9 postoperative study after emergent intervention (e) demonstrates reduction of the herniated lung, with internal and external the CC’s. c. d. fixation of the chest wall. • CC’s vascularize and calcify or ossify with age in various patterns which vary somewhat predictably by sex, age and Figure 1. race. 1-5, 10, 11 Diagrammatic representation of the costal cartilages, Learning Points • Calcification is present in most 20-80 year old patients, begins (blue,) in the thoracic cage. 1, 12, 13, 14 in the third decade, and may decrease plasticity. Adapted from Gray’s Anatomy, 20th edition, 1918. • 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,” Methods 2. In the mid-cartilage, or “midchondral” location, or After approval by our Institutional Review Board (IRB), a retrospective review of e. f. 3. At the costosternal/costomanubrial attachment. radiology reports and CT images from the radiology archive for the prospective diagnosis of • Potential complications mimic those of rib fractures, and include: costochondral injury in patients undergoing CT scan of the for trauma was performed. • Associated rib fractures and other costal cartilage injuries We used a medical search engine (Softek Illuminate, Prairie Village, KS, USA) to search a • Mediastinal hematomas 10 year time frame, (January 2003–December 2013,) in patients 18 years of age or greater. • Sternal, manubrial, clavicular, and pelvic fractures Data search utilized key phrases including “costal”, “chondral”, “cartilage” and • Pneumothorax and hemothorax “costochondral,” resulting in 44 cases. Each case was reviewed by a Radiologist with 15 • Chest wall lacerations and subcutaneous emphysema years post fellowship experience in trauma imaging to confirm the presence of costal • Greater awareness of spectrum of injuries and their appearances is intended to lead to cartilage injury. Review of the electronic medical record was conducted to determine greater recognition of this traumatic injury. Figure 4. associated injuries and complications. 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 Common Sites and Types of CC Injury fractures (f) are significantly displaced on this coronal view. References 1. 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 Figure 1: Distribution by Location 18 Figure 2: Distribution of Injuries for bone age assessment. J Forensic Sci. 2010;55(4):865-70. 16 3. Navani S, Shah JR, Levy PS. Determination of sex by costal cartilage calcification. Am J Roentgenol Radium Ther Nucl Med. 60 Associated Injuries / Complications 1970;108(4):771-4. 14 50 4. Rao NG, Pai LM. Costal cartilage calcification pattern--a clue for establishing sex identity. 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