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Published online: 2023-08-04

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Rare discovery of sacral “ribs”: a cadaveric case report

Jonathan A. Millard1, Kaivon Kouhestani1, Ahmed Qizilbash1, Christine Mayuga1, Casey Moore1, Kim A. Nguyen2, Paul Anthony Carpio1, Rachel E. Haley1


Supernumerary ribs are a well-documented congenital anomaly that can occur at any point of the vertebral column, most commonly in the cervical or lumbar region. However, accessory ribs found in the sacrococcygeal region are exceptionally rare and may be difficult to distinguish from other bony manifestations of the pelvic girdle. During cadaveric dissection, a pair of sacral “ribs” were found projecting from the left posterolateral sacral region. The bony projections shared a broad base from the posterior sacrum. The projections followed an anteroinferior trajectory, mimicking the thoracic rib structure. Computed tomography (CT) revealed further bony anomalies, including bilateral ossifications embedded in the sacrotuberous ligament, and a blunt bony protrusion extending toward the ischial spine. Most documented supernumerary ribs in the lumbar and sacrococcygeal regions are asymptomatic and are incidental findings in radiographic studies during the exploration of other medical complaints. Correlated symptoms mentioned in the literature include pelvic pain and decreased hip range of motion, with potential obstetric complications. Owing to their asymptomatic nature, sacral ribs may be underreported. The primary aim of this report is to provide a detailed description of these sacral “ribs” in the unique setting of a cadaveric dissection supplemented with medical imaging to enhance visualization.

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  1. Bohutová J, Kolár J, Vítovec J, et al. Accessory caudal axial and pelvic ribs. Rofo. 1980; 133(6): 641–643.
  2. Carbo G, Balliu E, Ortuño P, et al. Costilla sacra. Med Clin (Barc). 2015; 145(12): 556.
  3. Chang KZ, Likes K, Davis K, et al. The significance of cervical ribs in thoracic outlet syndrome. J Vasc Surg. 2013; 57(3): 771–775.
  4. Chernoff N, Rogers JM. Supernumerary ribs in developmental toxicity bioassays and in human populations: incidence and biological significance. J Toxicol Environ Health B Crit Rev. 2004; 7(6): 437–449.
  5. de Miguel I, Edouard F, Alvarez L, et al. Where ribs can be found in odd places. Spine J. 2007; 7(2): 256–257.
  6. Dieulafé R. Le coccyx: etude osteologique. Arch Anat Histol Embryol (Strasb). 1933; 16: 41–91.
  7. Evangelista P, Evangelista G. Dyspareunia associated with a pelvic digit. J Surg Case Rep. 2011; 2011(12): 7.
  8. Guidera KJ, Satterwhite Y, Ogden JA, et al. Nail patella syndrome: a review of 44 orthopaedic patients. J Pediatr Orthop. 1991; 11(6): 737–742.
  9. Goshen E, Schwartz A, Zilka LR, et al. Bilateral accessory iliac horns: pathognomonic findings in Nail-patella syndrome. Scintigraphic evidence on bone scan. Clin Nucl Med. 2000; 25(6): 476–477.
  10. Granieri GF, Bacarini L. The pelvic digit: five new examples of an unusual anomaly. Skeletal Radiol. 1996; 25(8): 723–726.
  11. Heligman D, Sullivan R, Millar E. Sacral ribs: a case report. Orthopedics. 1987; 10(10): 1439–1442.
  12. Henry BM, Vikse J, Sanna B, et al. Cervical rib prevalence and its association with thoracic outlet syndrome: a meta-analysis of 141 studies with surgical considerations. World Neurosurg. 2018; 110: e965–e978.
  13. Huang R, Zhi Q, Schmidt C, et al. Sclerotomal origin of the ribs. Development. 2000; 127(3): 527–532.
  14. Irnberger T. Beobachtung eines Rippenrudimentes am menschlichen Steissbein. Anat Anz. 1938; 86: 369–378.
  15. Kaushal SP. Sacral ribs. Int Surg. 1977; 62(1): 37–38.
  16. Khatri K, Goyal D, Paul R, et al. Two pelvic digits on same side: double trouble? J Clin Diagn Res. 2015; 9(6): RD04–RD05.
  17. Kitsoulis P, Galani V, Stefanaki K, et al. Osteochondromas: review of the clinical, radiological and pathological features. In Vivo. 2008; 22(5): 633–646.
  18. MacGibbon B, Farfan HF. A radiologic survey of various configurations of the lumbar spine. Spine (Phila Pa 1976). 1979; 4(3): 258–266.
  19. Miyakoshi N, Kobayashi A, Hongo M, et al. Sacral rib: an uncommon congenital anomaly. Spine J. 2015; 15(6): e35–e38.
  20. Moreta-Suárez J, de Ugarte-Sobrón OS, Sánchez-Sobrino A, et al. The pelvic digit: a rare congenital anomaly as a cause of hip pain. J Orthop Case Rep. 2012; 2(4): 19–22.
  21. Nakajima A, Usui A, Hosokai Y, et al. The prevalence of morphological changes in the thoracolumbar spine on whole-spine computed tomographic images. Insights Imaging. 2014; 5(1): 77–83.
  22. Nastoulis E, Karakasi MV, Pavlidis P, et al. Anatomy and clinical significance of sacral variations: a systematic review. Folia Morphol. 2019; 78(4): 651–667.
  23. Pais J, Levine A, Pais SO. Coccygeal ribs: development and appearance in two cases. AJR Am J Roentgenol. 1978; 131(1): 164–166.
  24. Pasinato G, Draily R, Launois PH, et al. Incidental discovery of a sacral rib: a case report. Surg Radiol Anat. 2023; 45(5): 661–663.
  25. Podgórski M, Gwizdała D, Flont P, et al. A symptomatic pelvic rib. Folia Morphol. 2018; 77(2): 406–408.
  26. Prescher A, Bohndorf K. Anatomical and radiological observations concerning ossification of the sacrotuberous ligament: is there a relation to spinal diffuse idiopathic skeletal hyperostosis (DISH)? Skeletal Radiol. 1993; 22(8): 581–585.
  27. Rashid M, Khalid M, Malik N. Sacral rib: a rare congenital anomaly. Acta Orthop Belg. 2008; 74(3): 429–431.
  28. Spadliński Ł, Cecot T, Majos A, et al. The epidemiological, morphological, and clinical aspects of the cervical ribs in humans. Biomed Res Int. 2016; 2016: 8034613.
  29. Steiner HA. Roentgenologic manifestations and clinical symptoms of rib abnormalities. Radiology. 1943; 40(2): 175–178.
  30. Sullivan D, Cornwell WS. Pelvic rib. Report of a case. Radiology. 1974; 110(2): 355–357.
  31. Van Breuseghem I. The pelvic digit: a harmless "eleventh" finger. Br J Radiol. 2006; 79(945): e106–e107.