Chalk Stick Fracture in Ankylosing Spondylitis

79 year old male. Back pain and lower extremity weakness after a fall • Xray of the Week

Figure 1.What are the important findings in each image.

Figure 2. Coronal CT (A) and sagittal CT (B) images demonstrate fracture at the T11-12 level with significant offset (red arrows) causing the neurologic deficit. Note also the extensive ankylosis throughout the spine. Axial CT image (C) demonstrates edema adjacent to the acute fracture (green arrows). Axial CT image (D) shows fused sacroiliac joints (yellow arrows).

Ankylosing Spondylitis:

Ankylosing spondylitis (AS) is a seronegative spondyloarthropathy and chronic inflammatory disease of the axial skeleton that leads to the partial or complete fusion and rigidity of the spine. The disease triggers the innate immune response to mobilize macrophages, CD4+ T cells, and CD8+ T cells into the paravertebral and sacroiliac entheses.1 Chronic enthesitis erodes the iliac component of the sacroiliac joints and forms vertical syndesmophytes along the spinal ligament or around the annulus fibrosus of intervertebral discs. These syndesmophytes may fuse at the intervertebral discs and vertebral bodies.2 Ossification of vertebral ligaments present as the dagger sign on X-ray, while ossification of the outer fibers of the annulus fibrosus presents as a bamboo spine.3 [Figs. 1,2] These inflammatory changes additionally lead to osteopenic vertebrae and reduced spinal mobility.

Chalk stick fracture:

Patients with AS should be monitored to prevent serious complications such as chalk stick fractures: a complete separation of fused vertebrae. The fused osteopenic bones in AS increase the rigidity of the bony spinal structure overall and the risk of patients experiencing low-energy fractures.4 Chalk stick fractures may lead to anterior subluxation and narrowing of the spinal canal.5 As in this case, nearly 67% of chalk stick fractures from AS present with neurologic deficits.6 They typically occur in the cervical spine (81%) followed by the thoracic (11%) and lumbar (8%) regions.7 Primary diagnosis of AS involves radiography of sacroiliac joints and symptomatic areas of the spine (Figs. 1,2). Because radiography may not detect early signs of AS, non-enhanced MRI is recommended in identifying early signs of disease.8

References:

1. Van Praet L, Van den Bosch F, Mielants H, Elewaut D. Mucosal inflammation in spondylarthritides: past, present, and future. Curr Rheumatol Rep. 2011;13(5):409-415. doi:10.1007/s11926-011-0198-2

2. Ward MM, Deodhar A, Gensler LS, et al. 2019 Update of the American College of Rheumatology/Spondylitis Association of America/Spondyloarthritis Research and Treatment Network Recommendations for the Treatment of Ankylosing Spondylitis and Nonradiographic Axial Spondyloarthritis. Arthritis Rheumatol. 2019;71(10):1599-1613. doi:10.1002/art.41042

3. Kumar RR, Jha S, Sharma A. Dagger sign of ankylosing spondylitis. Oxf Med Case Reports. 2019;2019(12):502-503. doi:10.1093/omcr/omz117

4. Chaudhary SB, Hullinger H, Vives MJ. Management of acute spinal fractures in ankylosing spondylitis. ISRN Rheumatol. 2011;2011:150484. doi:10.5402/2011/150484

5. Akhaddar A, Salami M. Fracture of the bamboo spine (chronic ankylosing spondylitis) after cervical injury. Pan Afr Med J. 2014;17:113. doi:10.11604/pamj.2014.17.113.3888

6. Westerveld LA, Verlaan JJ, Oner FC. Spinal fractures in patients with ankylosing spinal disorders: a systematic review of the literature on treatment, neurological status and complications. Eur Spine J. 2009;18(2):145-156. doi:10.1007/s00586-008-0764-0

7. Skarentzos K, Karamanou G, Chrysafis I, Papagoras C. Chalk-stick fracture in ankylosing spondylitis. Clin Rheumatol. 2020;39(8):2469-2470. doi:10.1007/s10067-020-05117-0

8. Bernard SA, Kransdorf MJ, Beaman FD, et al. ACR Appropriateness Criteria® Chronic Back Pain Suspected Sacroiliitis-Spondyloarthropathy. J Am Coll Radiol. 2017;14(5):S62-S70. doi:10.1016/j.jacr.2017.01.048

Eric Errampalli is a passionate medical student at the University of Missouri – Kansas City Six-Year BA/MD Program, with a steadfast commitment to becoming a radiologist. His fascination with the field stems from its integral role in healthcare and the endless possibilities for technological advancements waiting to be made. At UMKC, Eric has made significant contributions to the Radiology Interest Group, serving in various executive roles and currently as the interventional radiology chair. His leadership has inspired his peers to explore the field and discover the boundless opportunities for growth and impact. Beyond UMKC, Eric's interests have risen to a national level, as he serves on the Society of Interventional Radiology Medical Student Council Education Committee and TheRadRoom IR Team. Through these platforms, he has been instrumental in shaping the future of interventional radiology education and promoting awareness of the field among medical students.

Eric's passion for innovation extends beyond the classroom, as he strives to help drive change in the field of radiology through his medical entrepreneurial ventures. He believes that entrepreneurship can unlock untapped potential in the field and pave the way for transformative breakthroughs that can improve patient outcomes and revolutionize healthcare.

To stay up to date on Eric's journey and learn more about his work, follow Eric on Twitter @EricErrampalli and connect with him on LinkedIn www.linkedin.com/in/eric-errampalli/

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Kevin M. Rice, MD is the president of Global Radiology CME and is a radiologist with Cape Radiology Group. He has held several leadership positions including Board Member and 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. He was once again a semifinalist for a "Minnie" for 2021's Most Effective Radiology Educator by AuntMinnie.com. He has continued to teach by mentoring medical students interested in radiology. Everyone who he has mentored has been accepted into top programs across the country including Harvard, UC San Diego, Northwestern, Vanderbilt, and Thomas Jefferson.

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