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Acute Onset Knee Pain • Xray of the Week A 68 year old female presenting with acute onset knee pain following crush injury of knee. What is the diagnosis? Figure 1. Plain radiographs of the knee AP (A), and lateral (B). ​Figure 2. Plain radiographs of the knee AP (A), and lateral (B). Green arrow demonstrating the avulsion fracture fragment due to the ruptured quadriceps tendon. Figure 3. Sagittal ​MRI of the knee. T1 weighted image (A) and T2 weighted image (B). Green arrow demonstrating the ruptured quadriceps tendon with discontinuity and retraction. Discussion: The quadriceps muscle group is the primary extension mechanism of the knee and consists of the vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris.[1] The 4 tendons of these muscles insert onto the patella as the quadriceps tendon or sometimes referred to as the quadriceps expansion.The quadriceps tendon is composed of 3 layers:The superficial layer from the rectus femoris, the middle layer composed of the vastus lateralis and medialis, and the deeper layer from the vastus intermedius [1,2]. There is some variability on the anatomic configuration of the layers of the quadriceps tendon.The vastus medialis and vastus lateralis join the superficial and deep layers of the quadriceps tendon in varying proportions as the most common anatomic arrangement [2]. Quadriceps tendon injury may be secondary to repetitive microtrauma, weakening from underlying medical conditions such as gout, diabetes, collagen vascular diseases, chronic renal failure [3,4,5] or from strong deceleration injury. Additional predisposing factors include older age, obesity and steroid use [4]. Traumatic injuries may result in acute partial or complete tears, usually a few centimeters removed from the upper patellar pole [1]. Complete tendon rupture is usually a clinical diagnosis with loss of extensor function [2,4] and MRI is performed more for surgical planning and confirmation of diagnosis whereas in partial tendon ruptures, MRI serves a more critical role in diagnosis [2]. Initial evaluation with acutely injured patients tends to be with radiographs in the emergency department. Associated radiologic findings include suprapatellar mass usually composed of the retracted tendon and associated edema as well as a joint effusion [Figs.1,2] [4]. On lateral radiographs, disruption of the normal quadriceps outline may be identified as well as a soft tissue defect superior to the patella where a corresponding palpable defect may be felt on physical examination [4], similar to our case above [Figs.1,2]. On MRI, partial rupture of the quadriceps tendon usually is manifested by edema and heterogeneity of the quadriceps tendon. With complete rupture of the quadriceps tendon, MRI demonstrates retraction of the torn ends, and surrounding edema, and frequently a joint effusion [Fig.3] [1]. Treatment needs to be prompt and will be determined by degree of injury and rupture. Partial ruptures may be treated conservatively with immobilization, however complete tendon rupture with or without associated patellar fracture need emergent orthopedic evaluation and surgery in order to regain full function and prevent retraction and fibrosis [4]. References: 1. Bencardino JT, Rosenberg ZS, Brown RR, Hassankhani A, Lustrin ES, Beltran J (2000) Traumatic musculotendinous injuries of the knee: diagnosis with MR imaging. Radiographics. 20(suppl1):S103–S120. 2. Zeiss J, Saddemi SR, Ebraheim NA. MR imaging of the quadriceps tendon: normal layered configuration and its importance in cases of tendon rupture. AJR. 1992;159:1031-1034. 3. Kim, Y.H., Shafi, M., Lee, Y.S. et al. Spontaneous and simultaneous rupture of both quadriceps tendons in a patient with chronic renal failure. Knee Surg Sports Traumatol Arthrosc. 2006 Jan;14(1):55-59. 4. Nance EP Jr, Kaye JJ (1982) Injuries of the quadriceps mechanism. Radiology 142:301–307. 5. Bikkina RS, Chaljub G, Singh H, Allen SD. Magnetic resonance imaging of simultaneous bilateral quadriceps tendon rupture in a weightlifter: case report. J Trauma. 2002; 52(3):582-584.5. Alexandra (Sasha) Roudenko, MD is originally from Siberia, Russia and grew up in New York City. After graduating magna cum laude from Barnard College - Columbia University as a chemistry major, she was invited to join the prestigious Phi Beta Kappa Society. She then received her MD degree from New York University School of Medicine. Dr. Roudenko is currently a third year radiology resident at Mount Sinai West - St. Luke's and has developed a passion for body imaging. She is particularly interested in body MRI and plans on pursuing the subspecialty throughout her career. In 2016, Dr. Roudenko was awarded a fellowship in the Introduction to Academic Radiology program at ARRS. All posts by Sasha Roudenko, MD

Acute Onset Lateral Foot Pain • Xray of the Week 63 y.o. male presented with 1 hour of aching pain on the lateral aspect of the right midfoot after he felt a pop while climbing stairs. He had no loss of sensation, stiffness, or swelling, but pain limited his range of motion. Initial x-rays of the right foot and ankle were taken with a follow up right foot MRI. What is the diagnosis? Figure 1. Prior oblique (A), current oblique (B) and current frontal (C) radiographs of the right foot. Figure 2. Prior oblique (A), current oblique (B) and current frontal (C) radiographs of the right foot demonstrate interval migration of an os peroneum from its expected position at the calcaneocuboid joint to the lateral aspect of the calcaneus (red arrows). Figure 3. Prior (A) and current (B) lateral radiographs of the right foot demonstrate interval posterior migration of an os peroneum from its expected position at the calcaneocuboid joint to the lateral anterior aspect of the calcaneus (red arrows). Figure 4. Illustration of the normal peroneus longus tendon viewed from the lateral plantar aspect of the foot. The os peroneum is a small ossicle located within the substance of the peroneus longus tendon at the inferolateral aspect of the base of the cuboid. The peroneus longus tendon passes posterior to the lateral malleolus, then curves anteriorly and obliquely down the lateral side of the foot where it curves forward under the fibular trochlea of the calcaneus. The os Peroneum is present in the substance of the The peroneus longus tendon proximal to cuboid tuberosity/tunnel. The peroneus longus tendon then extends under the foot to insert on the inferolateral aspect of the base of the first metatarsal and the distal end of the medial cuneiform. Illustration by Raf Ratinam, MBBS. Figure 5. Illustration of the ruptured peroneus longus tendon viewed from the lateral plantar aspect of the foot. The os peroneum is retracted due to a complete tear of the peroneus longus tendon at the inferolateral aspect of the base of the cuboid. Illustration by Raf Ratinam, MBBS. Figure 6: GIF. Axial PD MR images of the right foot demonstrating a complete tear of the peroneus longus tendon (red arrow) with approximately 2 cm gap. The os peroneum (labeled) is retracted to the inferior peroneal retinaculum. Note the distal peroneus longus tendon (yellow arrow) continuing through its anatomical course to the first metatarsal base. Figure 7: GIF. Sagittal T1 MR images of the right foot demonstrating a complete tear of the peroneus longus tendon (red arrow) with approximately 2 cm gap. The os peroneum (labeled) is retracted to the inferior peroneal retinaculum. Note the distal peroneus longus tendon (yellow arrow) continuing through its anatomical course to the first metatarsal base. Figure 8: Sagittal T1 MR images of the right foot demonstrating a complete tear of the peroneus longus tendon (red arrow) with approximately 2 cm gap. The os peroneum (labeled) is retracted to the inferior peroneal retinaculum. Discussion The os peroneum is an accessory ossicle found within the substance of the peroneus longus tendon. Normally seen in up to 30% of people, the os peroneum is bipartite approximately 30% of the time, and unilaterally ossified approximately 40% of the time [1-2]. Painful Os Peroneum Syndrome (POPS) is a general term to describe pain that results in an array of conditions, including fracture of the ossicle, partial or complete rupture of the peroneus longus tendon [Figs. 5-7], or diastasis of the bipartite ossicle. Primary tenosynovitis or peroneus longus tendinosis can also be a source of pain in this region[2]. POPS should be considered in patients with pain in the lateral midfoot. Palpation over the ossicle will often elicit pain, although physical exam is frequently variable. POPS may be secondary to trauma in an acute setting; however, the initial injury is often missed and the patient can present with chronic pain[1]. Plain radiographs, MRI, and increasingly ultrasound are useful in the diagnosis of POPS. Os peroneum fragment separation of ≥6mm, or proximal displacement of the proximal fragment by ≥10mm from the calcaneocuboid joint on lateral radiograph has 100% concordance with full thickness peroneus longus tendon tear demonstrated by MRI [Figs. 5-7] [3]. Fragment separation of 2 mm or less, or proximal displacement of 8 mm or less is associated with normal tendons, partial thickness tear, or only tendinosis [3]. As seen in this case prior to the peroneus longus tendon rupture, the normal os peroneum location ranges between 7 mm proximal and 8 mm distal to the calcaneocuboid joint [Fig. 3A][3]. The peroneus longus is a powerful evertor of the foot, thus surgical intervention is often necessary to repair a fully torn tendon. Since POPS may arise from a wide spectrum of conditions, the treatment is based upon the specific pathology [4]. Radiologists play an essential role in the diagnosis of POPS, and should be familiar with the appearance of both the normal os peroneum, and the various pathologic processes which may affect this accessory ossicle. References: 1. Ghagas-Neto FA, Caracas de Souza, BN, Nogueira-Barbosa MH. Painful Os Peroneum Syndrome: Underdiagnosed Condition in the Lateral Midfoot Pain. Case Reports in Radiology 8739362 (2016): 1-4. 2. Oh SJ, Kim YH, Kim SK, et al. Painful Os Peroneum Syndrome Presenting as Lateral Plantar Foot Pain. Annals of Rehabilitation Medicine 36.1 (2012): 163-66. 3. Brigido MK, Fessell DP, Jacobson JA, et al. Radiography and US of os peroneum fractures and associated peroneal tendon injuries: initial experience. Radiology. 2005;237 (1): 235-41. 4. Malhotra R, et al. Peroneal Tendon Pathology Treatment & Management. Medscape, 10 May 2016. Web. 13 Feb. 2017 Jesse Chen, MD Radiology Resident - Northwell/Staten Island University Hospital Dr. Chen is a radiology resident (class of 2020) at Staten Island University Hospital. He started residency as a general surgeon at Medstar Washington Hospital Center in DC, but transferred to radiology after 2 years. He graduated Magna Cum Laude from the University of Pennsylvania and then attended medical school at Georgetown University. Dr. Chen is currently the secretary/treasurer of the New York State Radiological Society (NYSRS) Residents and Fellows Section. Shirley Hanna, MD Section Chief, Division of Musculoskeletal Imaging - Northwell/Staten Island University Hospital Certified by the American Board of Radiology in 2011, Dr. Shirley Hanna joined the Northwell/Staten Island University Hospital faculty in 2012 after completing her fellowship in musculoskeletal and breast imaging at Yale-New Haven Hospital. Dr. Hanna graduated Magna Cum Laude from Seton Hall University and attended medical school at Rutgers-New Jersey Medical School where she was a member of ΑΩΑ. Dr. Hanna completed her transitional year of residency at St. Joseph’s Hospital Health Center in Syracuse, NY followed by her radiology residency at Yale-New Haven Hospital. She is now the the section chief of MSK imaging and Associate Chair of Radiology at Northwell/Staten Island University Hospital. Marlena Jbara, MD Attending, Division of Musculoskeletal Imaging - Northwell/Staten Island University Hospital Certified by the American Board of Radiology in 2001, Dr. Marlena Jbara has served as a member of the Bone and Joint division of Radiology at Staten Island University Hospital - Northwell Health since joining the team in 2008. Dr. Jbara, a summa cum laude graduate of the BA-MD Program at the State University of New York, was actively recruited by Dr. Javier Beltran for his nationally recognized MRI musculoskeletal and body fellowship program. Dr. Jbara is a leader in Podiatric Radiology, and has published articles and book chapters on the shoulder, knee and ankle. Her current interests include MRI evaluation of the Diabetic Foot and MR assessment of altered biomechanics, with respect to the foot and ankle. Cheryl Lin, MD Attending, Division of Musculoskeletal Imaging - Northwell/Staten Island University Hospital Certified by the American Board of Radiology in 2012, Dr. Cheryl Lin attended the 7-year BA-MD combined Sophie Davis School of Biomedical Education and graduated from SUNY Downstate College of Medicine, completed diagnostic radiology residency training in Staten Island University Hospital and musculoskeletal radiology fellowship in SUNY Stony Brook University Hospital. Dr. Lin specializes in sports injury imaging, orthopedic oncologic imaging and biopsy, podiatric medicine, musculoskeletal and general ultrasound, and cardiac coronary CTA imaging. She is also Section Chief in General Ultrasonography, and has a special interest in image-guided head/neck biopsies and musculoskeletal interventions such as therapeutic and diagnostic injections of joints and soft tissues. Ratheesraj (Raf) Ratinam, MBBS Monash University. Melbourne, Australia Dr. Raf Ratinam worked for several years as a surgical registrar at Monash Health in Melbourne, Australia. He has taken time away from his clinical work to undertake a PhD in the Department of Anatomy and Developmental Biology at Monash University. The PhD looks at applications of 3-Dimensional printing in hand surgery. Raf has worked for ten years as a medical illustrator and before commencing graduate medicine at Melbourne University he was working full time as an animator. His interests include oil painting, sculpting, calligraphy and archery. Follow Dr. Ratinam on Twitter @RafRatinam

Penetrating Wound to the Chest • Xray of the Week An 18 year-old presents with an injury to chest. What is the diagnosis? Figure 1. AP and lateral chest x-ray showing foreign bodies. What is the diagnosis? Figure 2. Annotated AP and lateral chest x-ray showing nail penetrating the right ventricle. Clip represents entry wound of the nail (red arrow). Mild enlargement of cardiac silhouette indicating pericardial effusion. Figure 3. Commercial pneumatic nail gun. Safety release (blue arrow) must be fully depressed (in the direction of red arrow) for nail to be ejected. Discussion Workplace injuries due to pneumatic nail guns are common despite manufacture safety features. Those with increased risk are workers with limited experience using nail guns or with inadequate training on the use of the devices (1,2,3). Compared to injuries to the extremities, penetrating wounds to the heart are uncommon. Though rare, the morbidity and mortality of penetrating nail gun wounds to the heart are high (2). Due to the penetrating injury, blood can accumulate in the pericardial sac. The hemopericardiun can lead to cardiac tamponade which is an immediate life-threatening situation in addition to the damage done to the heart by the nail. Surgical approaches to repair cardiac injuries for penetrating nail gun injuries include sternotomy or anterolateral thoracotomy. A pericardiocentesis may be necessary to stabilize the patient before surgery can be performed. Due to the safety features of nail guns and the difficulty of accidentally shooting one’s self in the chest, homicidal or suicidal intent should be considered (4), especially if the nail is unbent, which indicates the wound was not a result of a ricochet (5). References: 1. Beaver, A. C., & Cheatham, M. L. (1999). Life-threatening nail gun injuries. The American surgeon, 65(12), 1113. https://www.ncbi.nlm.nih.gov/pubmed/10597056 2. Chirumamilla, V., Prabhakaran, K., Patrizio, P., Savino, J. A., Marini, C. P., & Zoha, Z. (2016). Pericardiocentesis followed by thoracotomy and repair of penetrating cardiac injury caused by nail gun injury to the heart. International journal of surgery case reports, 23, 98-100. http://www.sciencedirect.com/science/article/pii/S2210261216300815 3. Lipscomb, H. J., Dement, J. M., Nolan, J., & Patterson, D. (2006). Nail gun injuries in apprentice carpenters: risk factors and control measures. American journal of industrial medicine, 49(7), 505-513.https://www.ncbi.nlm.nih.gov/pubmed/16758488 4. McCorkell, S. J., Harley, J. D., & Cummings, D. (1986). Nail-Gun Injuries: Accident, Homicide, or Suicide?. The American journal of forensic medicine and pathology, 7(3), 192-195. https://www.ncbi.nlm.nih.gov/pubmed/3788906 5. Nadesan, K, A Fatal Nail Gun Injury - An Unusual Ricochet? Medicine, Science and the Law. January 2000 http://journals.sagepub.com/doi/pdf/10.1177/002580240004000116 Christopher Williamson, MSMP 1st year medical student Medical College of Georgia at Augusta University Jayanth Keshavamurthy, MBBS Assistant Professor of Radiology Department of Radiology and Imaging Medical College of Georgia at Augusta University https://webapps.gru.edu/PROD/iflapi.viewfac?CGInetid=JKESHAVAMURTHY

Bilateral wrist pain • Xray of the Week 72 y.o. male presented with chronic bilateral wrist and hand pain. What is the diagnosis? Figure 1. Bilateral frontal hand and wrist radiographs. Figure 2. Right wrist radiograph. There is obliteration the radiocarpal joint between radius and scaphoid (red arrow). There is scapholunate advanced collapse (SLAC) with scapholunate dissociation and marked proximal migration of the capitate (green arrow). Deformity of the scaphoid and distal radius (red arrow) is due to remodeling related to the arthropathy. Note the radioulnar joint is relatively spared and there is no chondrocalcinosis in the joints or in the triangular fibrocartilage. Figure 3. Left wrist radiograph. There is obliteration the radiocarpal joint between radius and scaphoid (yellow arrow). There is scapholunate advanced collapse (SLAC) with scapholunate dissociation and marked proximal migration of the capitate (green arrow). Deformity of the scaphoid and distal radius (red arrow) is due to remodeling related to the arthropathy. Note the radioulnar joint is spared and there is no chondrocalcinosis in the joints or in the triangular fibrocartilage. Discussion Scapholunate Advanced Collapse (SLAC wrist) is due to advanced injury of the scapholunate and volar radioscapholunate ligaments which may lead to rotatory subluxation of the scaphoid and scapholunate dissociation. As in this severe case, the capitate may migrate proximally into the widened scapholunate space and articulate with the distal radius. ​CPPD crystal deposition disease and trauma are the major causes of SLAC wrist. Calcium Pyrophosphate Deposition Disease (CPPD Arthropathy) has the same appearance as degenerative joint disease (DJD) demonstrating sclerosis, joint space narrowing, and osteophyte formation. However, it tends to affect joints which are usually not seen with degenerative joint disease such as the radiocarpal joint, elbow, or restricted to the patellofemoral compartment of the knee. The distribution tends to be symmetric. Chondrocalcinosis is not always seen radiographically despite the presence of calcium crystals in the joint, and subchondral cysts may be prominent. Treatment options for advanced cases of SLAC wrist include partial fusion such as four-corner arthrodesis, or complete wrist arthrodesis, scaphoidectomy, proximal row carpectomy (PRC), denervation, and radial styloidectomy. References: 1. Resnick D, Niwayama G, Goergen TG, et-al. Clinical, radiographic and pathologic abnormalities in calcium pyrophosphate dihydrate deposition disease (CPPD): pseudogout. Radiology. 1977;122 (1): 1-15 2. Helms CA, Vogler JB, Simms DA, et al. CPPD crystal deposition disease or pseudogout. RadioGraphics 1982; 2 (1); 40-52 3. Brower AC, USNR DJFMDCDRMC. Arthritis in Black and White. Saunders. ISBN:1416055959. Read it at Google Books - Buy it on Amazon 4. Saffar P. Chondrocalcinosis of the wrist. Journal of hand surgery (Edinburgh, Scotland). 29 (5): 486-93. 5. Resnick D, Utsinger PD. The wrist arthropathy of “pseudogout” occurring with and without chondrocalcinosis. Radiology 1974; 113:633-641. 6. Chen C, Chandnani VP, Kang HS, Resnick D, et-al. Scapholunate advanced collapse: a common wrist abnormality in calcium pyrophosphate dihydrate crystal deposition disease. Radiology. 1990;177 (2): 459-61. 7. Doherty W, Lovallo JL. Scapholunate advanced collapse pattern of arthritis in calcium pyrophosphate deposition disease of the wrist. J Hand Surgery. 1993;18(6):1095-1098 8. Merrell GA, McDermott EM, Weiss AP. Four-corner arthrodesis using a circular plate and distal radius bone grafting: a consecutive case series. J Hand Surg Am. 2008;33 (5): 635-42. 9. Steinbach LS, Resnick D. Calcium pyrophosphate dihydrate crystal deposition disease revisited. State of the Art. Radiology. 1996;200:1-9. Kevin M. Rice, MD is president of Global Radiology CME and serves as the Chief of Staff and Chair of the Radiology Department of Valley Presbyterian Hospital in Los Angeles, California and is a radiologist with Renaissance Imaging Medical Associates. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. Dr. Rice co-founded Global Radiology CME with Natalie Rice to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All posts by Kevin M. Rice, MD Steven Kussman, MD is a Musculoskeletal Radiologist at Renaissance Imaging Medical Associates in Los Angeles, California. After completing an undergraduate degree in Biology and graduating Magna Cum Laude at Brown University, he went on to Medical School at Boston University. Dr. Kussman was selected to the become a member of the prestigious Alpha Omega Alpha Honor Medical Society in 2008 and graduated Magna Cum Laude in 2009. He was Chief Radiology Resident at Boston University and completed his radiology residency at Boston University in 2014. Following residency, Dr. Kussman then did a one year fellowship in Musculoskeletal Imaging at UC San Diego in 2014-2015. Dr. Kussman's publications can be found here. He lives in Los Angeles with his wife and son and in his spare time loves to play and watch sports.

A 47-year-old status post rock climbing injury of his finger. Now has deformity of the palmar aspect of the finger with flexion. What is the diagnosis? Figure 1. What is abnormal in this digital image? A. Sagittal image of finger in flexion. B. Axial image of finger. C. Sagittal image of finger in extension. Figure 2. ABNORMAL FINGER A. Sagittal image of finger in flexion. The flexor tendon is bow stringed with respect to the proximal phalanx. (yellow arrow) B. Axial image of finger. There is a tear of the A1 pulley with retraction of the pulley fibers dorsally. The flexor digitorum superficialis tendon is split down the middle and mildly subluxed peripherally. Notice the marked soft tissue edema and tenosynovitis surrounding the flexor tendon. (green arrow) C. Sagittal image of finger in extension. The flexor tendon is less bow stringed with respect to the proximal phalanx when extended. (red arrow) Figure 3. NORMAL FINGER A. Sagittal image of the normal adjacent finger in flexion. Notice that the flexor tendons hug the palmar surface of the proximal phalanx. (yellow arrow) B. Axial image of the normal adjacent finger in flexion. Notice that the flexor tendons hug the palmar surface of the proximal phalanx. (green arrow) C. Sagittal image of the normal adjacent finger in extension. The flexor tendons hug the palmar surface of the proximal phalanx. (red arrow) Figure 4. Diagram of the normal digital flexor pulley system. Diagram from: https://theclimbingdoctor.com/pulley-injuries-explained-part-1/ Figure 5. Diagram of the normal digital flexor pulley system. Figure 6. Diagram of the digital flexor pulley system with a tear of the A2 and A3 pulleys. Figure 7. Intraoperative images of patient in Figure 1-3. A. First picture shows torn pulley. B. Palmaris graft harvested. C. Graft dorsal to bone and volar to extensor. D. Final picture tied down. Figure 8. Rock climbing with the crimp grip. Note the extension of the MCP joints, flexion of the PIP joints, and extension of the DIP joints. When using the crimp grip rather than an open hand grip, the force on the A4 pulley increases 3.9 times and the force on the A2 pulley increases 31.5 times. Discussion: The flexor tendons of the finger travel through a fibro-osseous tunnel along the palmar aspect of the fingers. The fibrous portion of the canal includes five annular pulleys which are perpendicular to the long axis of the tunnel and are separate areas of thickening of the tendon sheaths. There are also three cruciform pulleys which crisscross fibers of the annular pulleys. The annular pulleys are named A1 through A5 and the cruciate pulleys are named C1 through C3. The A1 pulley originates in the palmar plate of the metacarpal phalangeal joint and extends to the base of the proximal phalanx and is intimately related to the metacarpal phalangeal joint. The A2 pulley originates along the volar proximal aspect of the proximal phalanx and spans the distance to the distal third of the proximal phalanx. The A3 pulley spans over the proximal interphalangeal joint, A4 is located palmar to the mid aspect of the middle phalanx, while the A5 pulley spans the DIP joint. The main role of the annular pulleys is to stabilize the tendon sheaths to the phalanges. The function of the pulley system is to prevent bowstringing of the tendons on finger flexion. One analogy is the eyelets of a fishing rod. Flexor injuries are commonly encountered during forced extension on a flexed finger such as occurs when using the “crimp grip” during rock climbing. In fact, the crimp grip transfers 31.5 times more force on the A2 pulley than an open-hand grip. (Fig 8.) Flexor pulley injuries have also been reported in bowling, baseball and other sports. MRI is the main imaging method, however ultrasound is playing an increasingly important role in evaluation due to the possibility of dynamic assessment. All A2 and most A4 pulley ruptures require surgical repair in order to regain function. A1, A3 and A5 pulleys may be initially managed conservatively. References and further reading: 1. Singh AP. Flexor Tendon Pulley System of Hand. http://boneandspine.com/flexor-tendon-pulley-system-of-hand/ 2. Whitney Lowe W.Flexor Pulleys of the Fingers. Massage Today May, 2010, Vol. 10, Issue 05 http://www.massagetoday.com/mpacms/mt/article.php?id=14209 3. Awh MH. Pulley Lesions of the Fingers. http://radsource.us/pulley-lesion-of-the-fingers/ 4. Rock Climbers and Pulleys. http://musculoskeletalmri.blogspot.com/2011/05/rock-climbers-and-pulleys.html 5. Rubin DA, Kneeland JB, Kitay GS, Naranja RJ. Flexor Tendon Tears in the Hand: Use of MR Imaging to Diagnose Degree of Injury in a Cadaver Model. AJR 1996;166:615-620 6. Drape J, et al. Closed ruptures of the flexor digitorum tendons: MRI evaluation. Skeletal Radiology 1998;27:617-624. 7. Clavero JA, Alomar X, Monill JM, et. al. MR Imaging of Ligament and Tendon Injuries of the Fingers. RadioGraphics 2002 22:2, 237-256 8. Lin GT, Amadio PC, An KN, Cooney WP. Functional anatomy of the human digital flexor pulley system. J Hand Surg [Am ]1989; 14:949–956. 9. Crowley TP. The Flexor Tendon Pulley System and Rock Climbing. J Hand Microsurg (2012) 4: 25. 10. Zafonte, Brian et al. Flexor Pulley System: Anatomy, Injury, and Management. Journal of Hand Surgery ,2014, Volume 39 , Issue 12 , 2525 - 2532 11. Bianchia S, Martinoli C, de Gautarda R, et. al. Ultrasound of the digital flexor system: Normal and pathological findings. J Ultrasound. 2007 Jun; 10(2): 85–92. 11. Vigouroux L, Quaine F, Labarre-Vila A, Moutet F-O. Estimation of finger muscle tendon tensions and pulley forces during specific sport-climbing grip techniques. J Biomech. 2006;39:2583-2592. doi:10.1016/j.jbiomech.2005.08.027 12. Pulley Injuries in Fingers. http://bouldersuk.com/2013/11/pully-injuries-fingers/ Phillip Tirman, MD is the Medical Director of Musculoskeletal Imaging at the Renaissance Imaging Center in Westlake Village, California. A nationally recognized expert in the applications of MRI for evaluating MSK and spine disorders, Dr. Tirman is the co-author of three textbooks, including MRI of the Shoulder and Diagnostic Imaging: Orthopedics. He is also the author or co-author on over sixty original scientific articles published in the radiology and orthopedic literature. All posts by Phillip Tirman, MD Kevin M. Rice, MD is president of Global Radiology CME and serves as the Chief of staff and Chair of the Radiology Department of Valley Presbyterian Hospital in Los Angeles, California and is a radiologist with Renaissance Imaging Medical Associates. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. Dr. Rice co-founded Global Radiology CME with Natalie Rice to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All Posts by Kevin M Rice, MD

Fixed Abduction of Left Shoulder After a Fall • Xray of the Week 80 y.o. female with left shoulder pain and deformity after a fall. What is the diagnosis? Figure 1. Frontal left shoulder radiograph. Figure 2. Annotated frontal left shoulder radiograph. The humeral head is dislocated inferiorly (red arrow) and the shaft of the humerus is parallel to the scapular spine (yellow arrows). Figure 3. CT scan of left shoulder. A. Coronal image. There is inferior dislocation of the humeral head (red arrow) relative to the glenoid (yellow arrow). B. Sagittal image. There is inferior dislocation of the humeral head (red arrow) relative to the glenoid. Also note the well corticated old Bankart fracture of the anterior glenoid (yellow arrow) indicating previous anterior glenohumeral dislocation. Discussion Seen in less than 1% of cases, inferior shoulder dislocation is the rarest type of shoulder dislocation. The mechanism of injury is either sudden forceful arm hyperabduction or direct force on fully abducted arm. Luxatio erecta, refers to the abduction deformity that is a result of the of the humeral head situated inferior to the glenoid resulting in the patient presenting with the arm held upright. This injury has the has highest incidence of neurovascular injury of all types of shoulder dislocations with neurologic injury to the brachial plexus in up to 60% of cases and vascular injury to the axillary artery in up to 39% of cases. Plain radiographs in cases of inferior shoulder dislocation typically demonstrate the humeral head located inferior to the glenoid. The finding of fixed abduction of the shoulder with the shaft of the humerus parallel to the scapular spine (Figs. 1 and 2) is pathognomonic of luxatio erecta. Due to the high incidence of complications, MRI should be performed after the dislocation has been reduced. Common MRI findings include rotator cuff tears, glenoid labrum tears, and injury to both the anterior and posterior bands of the inferior glenohumeral ligament. Treatment consists of closed reduction and immobilization; however, surgery may be indicated in active patients who have capsulolabral damage or rotator cuff tear. • Rarely inferior hip dislocation can present with luxatio erecta as seen on this Global Radiology CME Case: Inferior Hip Dislocation with Luxatio Erecta References: 1. Yao F, Zhang L, Jing J. Luxatio erecta humeri with humeral greater tuberosity fracture and axillary nerve injury. Am J Emerg Med. 2018 Oct;36(10):1926.e3-1926.e5. https://www.ncbi.nlm.nih.gov/pubmed/30238913 2. Ngam PI, Hallinan JT, Sia DSY. Sequelae of bilateral luxatio erecta in the acute post-reduction period demonstrated by MRI: a case report and literature review. Skeletal Radiol. 2019 Mar;48(3):467-473. https://www.ncbi.nlm.nih.gov/pubmed/30151632 3. Carbone S, Papalia M, Arceri V, Placidi S, Carbone A, Mezzoprete R. Humeral head inferior subluxation in proximal humerus fractures. Int Orthop. 2018 Apr;42(4):901-907. https://www.ncbi.nlm.nih.gov/pubmed/29116358 4. Brady WJ, Knuth CJ, Pirrallo RG (1995) Bilateral inferior glenohumeral dislocation: luxatio erecta, an unusual presentation of a rare disorder. J Emerg Med 13:37–42. https://www.jem-journal.com/article/0736-4679(94)00110-3/pdf 5. Baba AN, Bhat JA, Paljor SD, et. al. Luxatio erecta: inferior glenohumeral dislocation—a case report. International Journal of Shoulder Surgery. 2007(1)3:100–102. https://doi.org/10.4103%2F0973-6042.34026 6. Yamamoto T, Yoshiya S, Kurosaka M, et. al. Luxatio erecta (inferior dislocation of the shoulder): a report of 5 cases and a review of the literature. Am J Orthop (Belle Mead NJ). 2003 Dec;32(12):601-603. https://www.ncbi.nlm.nih.gov/pubmed/14713067 7. Davids JR, Talbott RD (1990) Luxatio erecta humeri. A case report. Clin Orthop 252:144-149. https://www.ncbi.nlm.nih.gov/pubmed/2302879 8. Mallon WJ, Bassett FH, Goldner RD. Luxatio erecta: the inferior glenohumeral dislocation. J Orthop Trauma. 1990;4 (1): 19-24. https://doi.org/10.1097%2F00005131-199003000-00003 9. Camarda L, Martorana U, D'Arienzo M. A case of bilateral luxatio erecta. Journal of Orthopaedics and Traumatology, vol. 10, no. 2, pp. 97–99, 2009. https://doi.org/10.1007%2Fs10195-008-0039-x 10. Matsumoto K, Ohara A, Yamanaka K, Takigami I, Naganawa T. Luxatio erecta (inferior dislocation of the shoulder): a report of two cases and a review of the literature. Injury Extra. 2005;36:450–3. https://www.sciencedirect.com/science/article/pii/S1572346105000644?via%3Dihub 11. Mohseni MM. Images in emergency medicine: luxatio erecta (inferior shoulder dislocation). Ann Emerg Med. 2008;52:203–31. https://www.annemergmed.com/article/S0196-0644(07)01798-2/fulltext 12. Ngam PI, Hallinan JT, Sia DSY. Sequelae of bilateral luxatio erecta in the acute post-reduction period demonstrated by MRI: a case report and literature review. Skeletal Radiol. 2019 Mar;48(3):467-473. doi: 10.1007/s00256-018-3047-9 13. Hassanzadeh E, Chang CY, Huang AJ, et. al. CT and MRI manifestations of luxatio erecta humeri and a review of the literature. Clin Imaging. 2015 Sep-Oct;39(5):876-9. doi: 10.1016/j.clinimag.2015.04.009 14. Krug DK, Vinson EN, Helms CA. MRI findings associated with luxatio erecta humeri. Skeletal radiology. 39 (1): 27-33. doi:10.1007/s00256-009-0786-7 Kevin M. Rice, MD is president of Global Radiology CME and serves as the Chief of Staff of Valley Presbyterian Hospital in Los Angeles, California and is a radiologist with Renaissance Imaging Medical Associates. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. Dr. Rice co-founded Global Radiology CME with Natalie Rice to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All posts by Kevin M. Rice, MD

29F with trauma and headache • Xray of the Week Figure 1. What is the important finding on this CT scan. Figure 2. A. Coronal CT brain with standard window width of 70. It is very difficult to visualize the left superior parietal acute subdural hematoma. B. Coronal CT brain with wider window width of 150. Note the small superior parietal acute subdural hematoma (red arrow). Figure 3. Coronal and axial CT brain with standard window width of 70. It is very difficult to visualize the left superior parietal acute subdural hematoma. SDH is not well seen on the axial image, even on a wide window, due to the hematoma being in the same plane. Figure 4. Sagittal CT of a different patient with atrophy which demonstrates several bridging cortical veins (white arrows) as they cross the subdural space and drain into the superior sagittal sinus. Subdural hemorrhages are due to tearing of these veins when there is a rapid acceleration or deceleration of the head. Discussion: Acute subdural hematoma (SDH) occurs when blood accumulates in the subdural space, between the arachnoid and dura layers of the brain (1,4). They can result from traumatic accidents that cause tears in the bridging veins that cross the subdural space. Acute SDH's are common in the elderly because brain atrophy during aging causes the bridging veins to stretch, making them more susceptible to tears (2) (Fig. 4). Other etiologies of acute SDH include coagulopathy or medical coagulation, non-traumatic hemorrhage, surgery, and intracranial hypotension (3). Acute SDH's are typically unilateral and can be visualized as crescent-shaped and hyperdense regions on CT (1,4). The acute SDH in this case is seen only with wide windowing. Small SDH's such as the one in this case may be difficult to detect with standard brain windows compared to the subdural window so it is important to window the CT scan appropriately for smaller hematomas (1). In addition, this SDH was not well seen on the axial images due to the hematoma being in the same plane (Fig.3). SDH's can usually be distinguished from epidural hematomas since epidural hematomas have a biconcave-lens appearance on CT and show pooling of blood between the skull and the dura mater and they cannot expand past the sutures of the skull (1,4). Purulent accumulation of cerebrospinal fluid in the subarachnoid space can also have a similar appearance to SDH's, especially when there is decreased brain mass (4). Patients with subarachnoid hemorrhage due to ruptured aneurysms may also present with hyperdense subdural effusions which appear similar to acute SDH's but they may resolve on follow-up examination (5). Acute SDH can be distinguished from subacute and chronic SDH on CT. Subacute SDH will appear isodense to grey matter on CT (6). Chronic SDH will appear isodense to CSF on CT often with a biconvex shape rather than a crescentic shape, and it can also appear as a calcified mass (7). Treatment for acute SDH is usually surgical particularly when there is neurologic deficit. Moreover, surgery is indicated if the clot thickness is more than 1 cm or midline shift is more than 0.5 cm, even without significant neurologic deficit (8). Conservative management may be used in asymptomatic patients with small or chronic SDH (8). In this particular case, the SDH resolved without surgery. ​​​​ References: 1. Heit JJ, Iv M, Wintermark M. Imaging of Intracranial Hemorrhage. J Stroke. 2017;19(1):11-27. doi:10.5853/jos.2016.00563 2. Miller JD, Nader R. Acute subdural hematoma from bridging vein rupture: a potential mechanism for growth. J Neurosurg. 2014;120(6):1378-1384. doi:10.3171/2013.10.JNS13272 3. Vega RA, Valadka AB. Natural History of Acute Subdural Hematoma. Neurosurg Clin N Am. 2017;28(2):247-255. doi:10.1016/j.nec.2016.11.007 4. Pierre L, Kondamudi NP. Subdural Hematoma. [Updated 2019 Dec 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532970/ 5. Zamora CA, Lin DD. Enhancing subdural effusions mimicking acute subdural hematomas following angiography and endovascular procedures: report of 2 cases. J Neurosurg. 2015;123(5):1184-1187. doi:10.3171/2014.10.JNS142172 6. Yadav YR, Parihar V, Namdev H, Bajaj J. Chronic subdural hematoma. Asian J Neurosurg. 2016;11(4):330-342. doi:10.4103/1793-5482.145102 7. Kpelao E, Beketi KA, Moumouni AK, et al. Clinical profile of subdural hematomas: dangerousness of subdural subacute hematoma. Neurosurg Rev. 2016;39(2):237-240. doi:10.1007/s10143-015-0669-4 8. Gerard C, Busl KM. Treatment of Acute Subdural Hematoma. Curr Treat Options Neurol. 2014 Jan;16(1):275. doi: 10.1007/s11940-013-0275-0 Amara Ahmed is a medical student at the Florida State University College of Medicine. She serves on the executive board of the American Medical Women’s Association and Humanities and Medicine. She is also an editor of HEAL: Humanism Evolving through Arts and Literature, a creative arts journal at the medical school. Prior to attending medical school, she graduated summa cum laude from the Honors Medical Scholars program at Florida State University where she completed her undergraduate studies in exercise physiology, biology, and chemistry. In her free time, she enjoys reading, writing, and spending time with family and friends. Follow Amara Ahmed on Twitter @Amara_S98 All posts by Amara Ahmed Kevin M. Rice, MD is the president of Global Radiology CME Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All posts by Kevin M. Rice, MD

29F with trauma and headache • Xray of the Week Figure 1. What is the important finding on this CT scan. Figure 2. A. Axial CT brain showing epidural hematoma in frontal region (yellow arrow). B. Axial CT brain showing fracture of right frontal bone (red arrow) C. Coronal CT brain showing right frontal epidural hematoma extending across the midline to the left frontal region (yellow arrows). D. 3D CT showing linear fracture of right frontal bone (red arrow) and left parietal bone (green arrow). Discussion: Epidural hematomas (EDH) refer to bleeding between the skull and the dura mater (1). EDH can occur when skull fractures result in arterial or venous injuries, causing pooling of blood in the epidural space (1). The majority of EDH's are unilateral and supratentorial, and 20% are frontal (2). Damage to a branch of the middle meningeal artery is the most common source of bleeding, but some EDH's can be attributed to venous bleeding after laceration of a dural venous sinus (3). Patients with EDH may initially lose consciousness and then regain consciousness and appear normal during a “lucid interval” before losing consciousness again (4). This lucid interval is an important characteristic of EDH that may help in diagnosis. On CT scan, EDH's present as a hyperdense, biconvex-shaped mass. Whereas subdural hematomas are not limited by the sutures, EDH's usually do not cross suture lines since blood cannot expand beyond the point where the dura attaches to the cranial sutures (1). However, the EDH in this case is unique because it does cross the sagittal suture. This can occur when diastatic fractures cause widening of sutures, allowing blood to cross the suture lines (3,10). In this case, the fracture crosses the sagittal suture (Fig. 2D) with resultant acute bifrontal EDH. Larger EDH's can also present with midline shift or compression of the ventricles due to mass effect (3). In acute bleeding, the non-clotted fresh blood appears as areas of low density on CT, also known as a swirl sign (5). Subacute EDH occurs between days 2-4 and appears solid while chronic EDH occurs between days 7-20 and appears as mixed or lucent with contrast enhancement (3). MRI can also be used to visualize EDH as it is more sensitive than CT. The presence of the displaced dura as a hypointense line on T1 and T2 on MRI is a key finding in EDH (6). MRI can also be used to differentiate between acute and chronic EDH. Acute EDH appears isointense on T1 with varying intensities on T2 while chronic EDH appears hyperintense on T1 and T2 (6). Angiography of EDH can show tears of the middle meningeal artery. In rare cases, EDH can appear with a “tram track sign” on angiography due to extravasation of contrast into the paired meningeal veins (7, 8). Treatment for acute and symptomatic EDH is hematoma evacuation to reduce pressure on the brain (9). Burr hole evacuation can also be used, and craniotomy may be necessary in large hematomas (3, 9). Non-surgical treatment is rare, but can be appropriate if there is a midline shift less than 5 mm, an EDH volume less than 30 ml, clot diameter less than 15 mm, and Glasgow Coma Score greater than 8 with no focal neurological symptoms (3). Follow up includes neurological examinations and surveillance with brain imaging to ensure that the hematoma does not expand (3, 9). ​​​​ References: 1. Heit JJ, Iv M, Wintermark M. Imaging of Intracranial Hemorrhage. J Stroke. 2017;19(1):11-27. doi:10.5853/jos.2016.00563 2. Bonfante, Eliana, and Roy Riascos. “Imaging of Brain Concussion.” Neuroimaging Clinics of North America, vol. 28, no. 1, Feb. 2018, p. i. doi:10.1016/S1052-5149(17)30140-5. 3. Khairat A, Waseem M. Epidural Hematoma. [Updated 2020 Jul 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK518982/ 4. Ganz JC. The lucid interval associated with epidural bleeding: evolving understanding. J Neurosurg. 2013;118(4):739-745. doi:10.3171/2012.12.JNS121264 5. Gupta VK, Seth A. "Swirl Sign" in Extradural Hematoma. World Neurosurg. 2019;121:95-96. doi:10.1016/j.wneu.2018.10.010 6. Marincek BF, Dondelinger RF. Emergency Radiology: Imaging and Intervention. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg; 2007:109-110. doi:10.1007/978-3-540-68908-9 7. Yu J, Guo Y, Xu B, Xu K. Clinical importance of the middle meningeal artery: A review of the literature. Int J Med Sci. 2016;13(10):790-799. Published 2016 Oct 17. doi:10.7150/ijms.16489 8. Paiva WS, Andrade AF, Amorim RL, et al. Computed tomography angiography for detection of middle meningeal artery lesions associated with acute epidural hematomas. Biomed Res Int. 2014;2014:413916. doi:10.1155/2014/413916 9. Ren H, Yin L, Ma L, Wei M, Ma X. Emergency bedside evacuation of a subset of large postoperative epidural hematomas after neurosurgical procedures. Medicine (Baltimore). 2018;97(30):e11475. doi:10.1097/MD.0000000000011475 10. Huisman TA, Tschirch FT. Epidural hematoma in children: do cranial sutures act as a barrier?. J Neuroradiol. 2009;36(2):93-97. doi:10.1016/j.neurad.2008.06.003 Amara Ahmed is a medical student at the Florida State University College of Medicine. She serves on the executive board of the American Medical Women’s Association and Humanities and Medicine. She is also an editor of HEAL: Humanism Evolving through Arts and Literature, a creative arts journal at the medical school. Prior to attending medical school, she graduated summa cum laude from the Honors Medical Scholars program at Florida State University where she completed her undergraduate studies in exercise physiology, biology, and chemistry. In her free time, she enjoys reading, writing, and spending time with family and friends. Follow Amara Ahmed on Twitter @Amara_S98 All posts by Amara Ahmed Kevin M. Rice, MD is the president of Global Radiology CME Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All posts by Kevin M. Rice, MD

48 year old male with chest pain following a motor vehicle collision • Xray of the Week Figure 1. Name the important findings on this CXR and CT Scan. Figure 2. Imaging results of a trauma patient who was in a motor vehicle collision. A: Chest X-ray demonstrating a widening of the mediastinum (yellow arrows). B: Axial CT image of the chest showing subtle pseudoaneurysm along the lateral aspect of the aortic arch (red arrow). C: Coronal CT image of the chest showing hematoma adjacent to the site aortic injury (blue arrow). Figure 3. Same patient as in figure 2, one month after aortic stent graft. A: Chest X-ray showing a normal width of the mediastinum after the placement of the stent graft (yellow arrow). B & C: Axial and coronal CT images of the chest showing a good expansion of the stent without adjacent hematoma or leak (red and blue arrows). Figure 4. Traumatic Aortic Injury Grading System (5)- Diagram by Han Ngo Grade 1: Intimal flap/intimal tear. Grade 2: Intramural hematoma (hemorrhage without an intimal tear). Grade 3: Aortic pseudoaneurysm (false aortic rupture contained by the thin wall of adventitia). Grade 4: Aortic transection (true aortic rupture due to the damage of all three layers). Discussion: Thoracic aortic injury is the most common type of traumatic aortic injury (TAI), a life-threatening condition that frequently occurs as a result of crush or deceleration injuries. As the second most common cause of death in patients with blunt trauma, TAI has a very high mortality rate with up to 80% of patients die at the scene of trauma and of those who survive the arrival to the ER, 30% die within the first 24 hours (1). Early diagnosis of TAI relies on appropriate imaging since clinical symptoms and examination are nonspecific. Chest X-ray can detect indirect signs of TAI such as widened mediastinum (Figs. 1,2), trachea displacement, depression of left main bronchus, obliteration of aortic knob contour, left apical pleural cap, or hemothorax. Although nonspecific, these findings should raise high suspicion for TAI when present in blunt trauma cases. CT scan can reveal direct signs of TAI through the visualization of aortic injuries (Figs. 1,2). Aortic injuries are categorized into four grades based on severity: intimal flap, intramural hematoma, pseudoaneurysm, or aortic transection (2-5) (Fig. 4). This is a case of Grade 3 injury due to the presence of a pseudoaneurysm (Fig. 1,2). Aortic stent graft (Fig. 3) is the preferred treatment for TAI because of its higher success rate and lower rate of complication than open surgical repair. The stent is placed by inserting a catheter with the compressed stent through an artery, most commonly the femoral artery. Once the stent reaches the site of aortic lesion, it is expanded to form a new aortic wall and prevent more blood from entering the pseudoaneurysm (3-5). ​​​​ References: 1. Igiebor OS, Waseem M. Aortic Trauma. StatPearls Publishing LLC. https://www.ncbi.nlm.nih.gov/books/NBK459337/. Published December 16, 2019. Accessed June 30, 2020. 2. Yahia DAA, Bouvier A, Nedelcu C, et al. Imaging of thoracic aortic injury. Diagn Interv Imaging. 2015;96(1):79-88. doi:10.1016/j.diii.2014.02.003 3. Mokrane FZ, Revel-Mouroz P, Saint Lebes B, Rousseau H. Traumatic injuries of the thoracic aorta: The role of imaging in diagnosis and treatment. Diagn Interv Imaging. 2015;96(7-8):693-706. doi:10.1016/j.diii.2015.06.005 4. Yamane BH, Tefera G, Hoch JR, et al. Blunt thoracic aortic injury: Open or stent graft repair? Surgery. 2008;144(4):575-582. doi:10.1016/j.surg.2008.06.007 5. Azizzadeh A, Keyhani K, Miller CC, et al. Blunt traumatic aortic injury: Initial experience with endovascular repair. J Vasc Surg. 2009 Jun;49(6):1403-8. doi:10.1016/j.jvs.2009.02.234 Han Ngo is a medical student at Oakland University William Beaumont School of Medicine (OUWB) in Rochester, Michigan. She graduated from UCLA, receiving her B.S. degree in Biochemistry. Prior to starting medical school, Han spent 4+ years (including her undergraduate years) working as a medical scribe for a psychiatrist at Ronald Reagan UCLA Medical Center. Interested in radiology, Han is now serving as the President of both diagnostic radiology and interventional radiology interest groups at OUWB. She is also a committee member on the Medical Student Council of the Society of Interventional Radiology (SIR). After deciding on her specialty, Han plans to continue learning and striving to make a difference in patients’ lives. Follow Han Ngo on Twitter @Han_Ngoo All posts by Han Ngo Kevin M. Rice, MD is the president of Global Radiology CME Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All posts by Kevin M. Rice, MD

Forced plantar flexion on an extended foot. Anterior ankle pain and weakness • Xray of the Week What is the diagnosis? Figure 1. What is the important finding on this MRI of the ankle. Figure 2. A: T1 weighted axial image with tibialis anterior rupture (yellow arrow). B: T1 weighted sagittal image with tibialis anterior tendon discontinuity, retraction and soft tissue edema (yellow arrow). C: T2 weighted axial image with tibialis anterior rupture (yellow arrow). D: T2 weighted sagittal image with tibialis anterior tendon discontinuity, retraction, and soft tissue edema (yellow arrow). Discussion: Anterior ankle tendinopathy can involve the tibialis anterior, extensor digitorum longus, or extensor hallucis longus. Anatomically, the anterior tibialis muscle tendon inserts at the plantar and medial aspect of the first metatarsal and cuneiform bones (4). The tibialis anterior muscle is the main dorsiflexor for the foot. Since the tendon is under the retinaculum, mechanical demand is less compared to the other tendons, leading to less irritation and tearing (4). Rupture of the tibialis anterior tendon can occur due a sudden force typically in the opposite direction of tendon function: forced plantar flexion of an extended foot. Rupture can also occur with degenerative processes typically affecting the distal avascular portion of the tendon (1). These degeneration etiologies can include impingement, inflammatory arthritis, diabetes mellitus, or chronic microtrauma leading to tendinosis (4). Upon tendon rupture, patients may present with anterior ankle pain and weakness. In addition, there may be a painless mass on the anteromedial aspect of the ankle due to the ruptured tendon and adjacent inflammation. Patients can have delayed presentation due to the compensation of the extensor hallucis longus and extensor digitorum muscles (1,3). This injury typically presents more in an older population due to the decreased tendon elasticity (2). In this case, the patient presented due to forced plantar flexion on an extended foot leading to a retracted full thickness tear. Imaging can prove helpful in making the diagnosis of tendon rupture, especially when the clinical and physical findings are vague. When evaluating an MR image of the ankle, normal tendons have low signal intensity on all sequences (4). With complete anterior tibial tendon rupture, discontinuity and retraction of the proximal tendon segment is apparent (4). Figures 2B and 2D demonstrate discontinuity, with rupture of the tendon and adjacent soft tissue swelling. In the setting of a tendon rupture, the tibialis anterior tendon is visualized on the medial side of the ankle with surrounding edema denoted by the yellow arrow on Figures 2A and 2C. Common sequelae of tendon rupture include foot drop, flatfoot, and compromised gait (3). Initial treatment includes conservative methods such as casting or orthotics. Surgery with direct repair or reconstruction may be indicated in athletes or after failure of conservative management (3). ​​​​ References: Waizy H, Bouillon B, Stukenborg-Colsman C, et al. Ruptur der Musculus-tibialis-anterior-Sehne : Ätiologie, klinische Symptome und Therapie [Rupture of the tendon of the tibialis anterior muscle : Etiology, clinical symptoms and treatment]. Unfallchirurg. 2017;120(12):1015-1019. doi:10.1007/s00113-017-0417-z Kausch T, Rütt J. Subcutaneous rupture of the tibialis anterior tendon: review of the literature and a case report. Arch Orthop Trauma Surg. 1998;117(4-5):290-293. doi:10.1007/s004020050250 Christman-Skieller C, Merz MK, Tansey JP. A systematic review of tibialis anterior tendon rupture treatments and outcomes. Am J Orthop (Belle Mead NJ). 2015;44(4):E94-E99. https://pubmed.ncbi.nlm.nih.gov/25844597/ Khoury NJ, el-Khoury GY, Saltzman CL, Brandser EA. Rupture of the anterior tibial tendon: diagnosis by MR imaging. AJR Am J Roentgenol. 1996;167(2):351-354. doi:10.2214/ajr.167.2.8686602 Amer Ahmed is a fourth-year medical student at Midwestern University Chicago College of Osteopathic Medicine. There, he has served as the President for the Medical Business Association and Secretary for the Radiology Interest Group. Before medical school, Amer earned a degree in Economics at Loyola University Chicago and spent some time as an Investment Specialist at Merrill Edge before deciding to pursue his interest in medicine. Radiology intrigued Amer following a back injury requiring him to get an MRI. That is when he was able to appreciate the eye for detail Radiologists possess. Amer is passionate about finance, medicine, and technology. Follow Amer Ahmed on Twitter @amer_ahmed401 All posts by Amer Ahmed Phillip Tirman, MD is the Medical Director of Musculoskeletal Imaging at the Renaissance Imaging Center in Westlake Village, California. A nationally recognized expert in the applications of MRI for evaluating MSK and spine disorders, Dr. Tirman is the co-author of three textbooks, including MRI of the Shoulder and Diagnostic Imaging: Orthopedics. He is also the author or co-author of over sixty original scientific articles published in the radiology and orthopedic literature. All posts by Phillip Tirman Kevin M. Rice, MD is the president of Global Radiology CME Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All posts by Kevin M. Rice, MD

28 yo male with wrist pain due to a fall • Xray of the Week What is the eponymous name of this fracture? Figure 1: Type 1 Smith fracture: Volar displacement of distal fragment of radius fracture (blue arrow). Note that this is an extraarticular fracture. Figure 2: Type 2 Smith fracture in a different patient: Volar and proximal displacement of distal fragment of radius fracture (blue arrow). Note that this is an intraarticular fracture (yellow arrow). Figure 3: Mechanism of injury for Smith fracture. Diagram by Shama Jaswal. Discussion: A Smith fracture or a reverse Colles fracture is an extraarticular fracture of the distal radius with a volar displacement or angulation of the distal fragment (Figs. 1,2). It was named by Irish surgeon Robert William Smith in 1847, who incidentally followed Abraham Colles as Professor of Surgery at Trinity College in Dublin [1]. Smith fractures are rare, making up approximately 5% of all radial and ulnar fractures combined. It commonly occurs either after a fall onto a flexed wrist or as a direct blow to the dorsal aspect of the wrist (Fig. 3). One of the diagnostic criteria includes deformed wrist with swelling visible on the volar side and the prominence of the ulna along the dorsum of the wrist [1]. Up to 15% of these fractures may show symptoms related to compression of the median and/or ulnar nerve; therefore, neurovascular evaluation is imperative [2,3]. Standard wrist radiographs are usually adequate to differentiate between Colles and Smith fractures. (Figs. 1,2) [4]. When there is extensive comminution or intra-articular fracture, CT helps define the injury and assist with surgical planning. Disruption of the distal radioulnar joint (DRUJ) and the triangular fibrocartilage complex (TFCC) are often seen along with other soft tissue injuries which are well assessed with MRI [5]. Smith fracture is divided into three types: [6] • Type I - most common type, accounting for about 85% of cases, is an extraarticular fracture through the distal radius (Fig. 1) • Type II - less common, accounting for approximately 13%, is an intraarticular oblique fracture, also referred to as a reverse Barton fracture (Fig. 2) • Type III - uncommon, less than 2%, is a juxta-articular oblique fracture The mainstay of treatment of non-displaced and stable distal radius fractures is closed reduction and immobilization [6]. Closed reduction using percutaneous pinning with K-wires can be performed in patients with good bone quality and minimal comminution [6,7]. For an unstable or irreducible fracture, ORIF with a volar plate is required [8-11]. Complications include malunion and compression of the median nerve causing carpal tunnel syndrome [12]. Entrapment of the extensor pollicis longus (EPL) tendon with malunion is seen in both conservative and ORIF surgeries [13-15]. Late rupture of the EPL has been demonstrated previously [16, 17]. Similarly development of complex regional pain syndrome (CRPS) has been reported in up to nearly 40% of fractures [18]. ​​​​ References: 1. Shah, H.M. and K.C. Chung, Robert William Smith: his life and his contributions to medicine. J Hand Surg Am, 2008. 33(6): p. 948-51 DOI: 10.1016/j.jhsa.2007.12.020 2. Ford, D.J. and M.S. Ali, Acute carpal tunnel syndrome. Complications of delayed decompression. J Bone Joint Surg Br, 1986. 68(5): p. 758-9. 3. McKay, S.D., et al., Assessment of complications of distal radius fractures and development of a complication checklist. J Hand Surg Am, 2001. 26(5): p. 916-22 DOI: 10.1053/jhsu.2001.26662 4. Dóczi, J., et al., Occult distal radial fractures. J Hand Surg Br, 1995. 20(5): p. 614-7 DOI: 10.1016/s0266-7681(05)80121-4 5. Mills, T.J., Smith's fracture and anterior marginal fracture of radius. Br Med J, 1957. 2(5045): p. 603-5 DOI: 10.1136/bmj.2.5045.603 6. Schroeder, J.D. and M. Varacallo, Smith's Fracture Review, in StatPearls. 2020, StatPearls Publishing Copyright © 2020, StatPearls Publishing LLC.: Treasure Island (FL). 7. Glickel, S.Z., et al., Long-term outcomes of closed reduction and percutaneous pinning for the treatment of distal radius fractures. J Hand Surg Am, 2008. 33(10): p. 1700-5 DOI: 10.1016/j.jhsa.2008.08.002 8. Downing, N.D. and A. Karantana, A revolution in the management of fractures of the distal radius? J Bone Joint Surg Br, 2008. 90(10): p. 1271-5 DOI: 10.1302/0301-620x.90b10.21293 9. Orbay, J.L. and A. Touhami, Current concepts in volar fixed-angle fixation of unstable distal radius fractures. Clin Orthop Relat Res, 2006. 445: p. 58-67 PubMed: https://pubmed.ncbi.nlm.nih.gov/16505728/ DOI:10.1097/01.blo.0000205891.96575.0f 10. Schneppendahl, J., J. Windolf, and R.A. Kaufmann, Distal radius fractures: current concepts. J Hand Surg Am, 2012. 37(8): p. 1718-25 DOI: 10.1016/j.jhsa.2012.06.001 11. Tang, J.B., Distal radius fracture: diagnosis, treatment, and controversies. Clin Plast Surg, 2014. 41(3): p. 481-99 DOI: 10.1016/j.cps.2014.04.001 12. Mackinnon, S.E., Pathophysiology of nerve compression. Hand Clin, 2002. 18(2): p. 231-41 DOI: 10.1016/s0749-0712(01)00012-9 13. Franz, T., Entrapment of Extensor Pollicis Longus Tendon after Volar Plating of a Smith Type Pediatric Distal Forearm Fracture. J Hand Surg Asian Pac Vol, 2016. 21(2): p. 253-6 DOI: 10.1142/s2424835516720085 14. Mansour, A.A., 3rd, J.T. Watson, and J.E. Martus, Displaced dorsal metaphyseal cortex associated with delayed extensor pollicis longus tendon entrapment in a pediatric Smith's fracture. J Surg Orthop Adv, 2013. 22(2): p. 173-5 DOI: 10.3113/jsoa.2013.0173 15. Murakami, Y. and K. Todani, Traumatic entrapment of the extensor pollicis longus tendon in Smith's fracture of the radius-case report. J Hand Surg Am, 1981. 6(3): p. 238-40 DOI: 10.1016/s0363-5023(81)80076-7 16. Bonatz, E., T.D. Kramer, and V.R. Masear, Rupture of the extensor pollicis longus tendon. Am J Orthop (Belle Mead NJ), 1996. 25(2): p. 118-22. 17. Roth, K.M., et al., Incidence of extensor pollicis longus tendon rupture after nondisplaced distal radius fractures. J Hand Surg Am, 2012. 37(5): p. 942-7 DOI: 10.1016/j.jhsa.2012.02.006 18. Li, Z., et al., Complex regional pain syndrome after hand surgery. Hand Clin, 2010. 26(2): p. 281-9 DOI: 10.1016/j.hcl.2009.11.001 Shama Jaswal is an International Medical Graduate, currently doing research at Mallinckrodt Institute of Radiology (MIR), Saint Louis. She aims at pursuing Diagnostic Radiology residency and poses a keen interest in research alongside academics. At MIR, she has been fortunate to work on various oncology projects including the project in which they studied how the difference in fat metabolism in both sexes can affect the cancer survival and outcome, and how this study can further improve prognosis through treatment modification. Shama is both an accomplished sprinter and singer having won several national competitions in in each discipline in India. She also has a strong passion for cooking and gardening. Follow Shama Jaswal on Twitter @Jaswal_Shama All posts by Shama Jaswal Kevin M. Rice, MD is the president of Global Radiology CME Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All posts by Kevin M. Rice, MD

Trauma. Wrist pain. • Xray of the Week Figure 1. What is the diagnosis? Figure 2. A. PA radiograph of lunate dislocation with triangular, “piece of pie” lunate appearance (green arrows), disruption of carpal arcs, increased radiolunate space, and overlap of lunate with other carpals. B. Lateral radiograph showing the “spilled teacup” appearance of lunate dislocation (yellow arrows), with the concavity of the lunate facing anteriorly. The lunate has volar displacement and angulation, and has lost articulation with the radius and capitate. Discussion: Lunate dislocations are typically a consequence of traumatic forces causing wrist hyperextension, such as a fall on an outstretched hand (1,2). Mayfield and colleagues described a progression of perilunate dislocation, with complete lunate dislocation representing the final stage of ligamentous and osseous failure with the greatest degree of carpal instability (Fig. 3) (2,3). Herzberg et al. further classified lunate dislocation according to volar displacement and rotation, with degree of rotation corresponding to increased probability of soft-tissue interposition and decreased likelihood of successful closed reduction (1,4). Patients may present with wrist swelling and pain, reduced range of motion, and symptoms of median nerve impingement (2). Figure 3. Mayfield Classification of Carpal Dislocations. from https://wikem.org/wiki/Perilunate_and_lunate_dislocations On plain radiographs, the PA view is useful for evaluating Gilula’s carpal arcs, three contours normally formed by the proximal and distal carpal rows that are interrupted by lunate dislocation (2,5). Figures 1A and 2A demonstrate this finding, along with overlapping of the lunate with the capitate, increased radiolunate distance, loss of total carpal height, and triangular “piece of pie” lunate appearance (1,2,5). The lateral radiograph is useful for detecting palmar dislocation and rotation of the lunate. Figures 1B and 2B show volar dislocation of the lunate from the lunate fossa, volar angulation of the lunate, loss of articulation and alignment with the radius and capitate, an abnormal scapho-lunate angle, and a “spilled teacup” appearance (1,2,5). The lateral view can also distinguish lunate dislocation from perilunate dislocation, in which the lunate remains articulated with the radius and the remainder of the carpal bones are displaced dorsally (1,2). Evaluation of wrist pathology can also be aided by CT, US, or fluoroscopy when radiographs are indeterminate (1,6). Diagnosis of lunate and perilunate dislocation following wrist trauma is missed in up to 25% of cases, and reduction and ligament repair are necessary to prevent joint dysfunction (4). Late presentation can lead to avascular necrosis (2). Even with early treatment, however, over 50% of patients in a multi-center study experienced post-traumatic arthritis (4). Other complications include wrist pain and stiffness, median nerve injury, tendon rupture, and carpal instability (1,2,5). Closed reduction was previously the recommended treatment and is employed in the acute setting, though open reduction with fixation and ligament repair is now preferred (1,2). ​​​​ References: 1. Scalcione LR, Gimber LH, Ho AM, Johnston SS, Sheppard JE, Taljanovic MS. Spectrum of carpal dislocations and fracture-dislocations: imaging and management. AJR Am J Roentgenol. 2014;203(3):541-550. doi:10.2214/AJR.13.11680 2. Grabow RJ, Catalano L 3rd. Carpal dislocations. Hand Clin. 2006;22(4):485-vii. doi:10.1016/j.hcl.2006.07.004 3. Mayfield JK, Johnson RP, Kilcoyne RK. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg Am. 1980;5(3):226-241. doi:10.1016/s0363-5023(80)80007-4 4. Herzberg G, Comtet JJ, Linscheid RL, Amadio PC, Cooney WP, Stalder J. Perilunate dislocations and fracture-dislocations: a multicenter study. J Hand Surg Am. 1993;18(5):768-779. doi:10.1016/0363-5023(93)90041-Z 5. Tucker A, Marley W, Ruiz A. Radiological signs of a true lunate dislocation. BMJ Case Rep. 2013;2013:bcr2013009446. Published 2013 Apr 23. doi:10.1136/bcr-2013-009446 6. Kim K, Kim MW. Ultrasonography Detected Missed Lunate Volar Dislocation Associated With Median Neuropathy: A Case Report. Ann Rehabil Med. 2017;41(4):709-714. doi:10.5535/arm.2017.41.4.709 Ian Rumball is a medical student and aspiring radiologist at the Zucker School of Medicine at Hofstra/Northwell in Hempstead, NY. He serves as chair for his school’s radiology interest group. Prior to medical school, he attended the University of Wisconsin - Madison and graduated with degrees in biology, history, global health, and African studies. As an undergraduate, he did research in the fields of oncology, hematology, and neuroendocrinology. He also published work in undergraduate journals of creative writing, history, and physiology. In his free time, Ian enjoys playing guitar, hiking his local state parks, and watching classic films. Follow Ian Rumball on Twitter @RumballIan All posts by Ian Rumball Kevin M. Rice, MD is the president of Global Radiology CME Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. Follow Dr. Rice on Twitter @KevinRiceMD All posts by Kevin M. Rice, MD