Lateralized Odontoid in Plain Film Radiography: Sign of Fractures? – A Comparison Study with MDCT

Abstract

Purpose: To evaluate X-ray standards for the detection of odontoid fractures. Summary of background data: Cervical spine fractures are a common finding in emergency medicine, accounting for 1 – 3 % of injuries. Involvement of the C1 / C2 complex is found in 25 % of cases, affecting the odontoid peg in 55 – 80 %. Regarding the consequences of missed fractures, radiographic techniques built the groundwork for further treatment procedures. As standardized X-ray measurements have not been established, the incidence of unrecognized cervical spine fracture is expected to be up to 20 %. The establishment of X-ray-based guidelines is also limited by the presumed low specificity and sensitivity of distance measurements caused by rotational distortion which leads to a rising popularity of CT.

Materials and Methods: 79 (age 60 ± 26 yrs) patients with lateralization of the odontoid process on conventional plain film radiography (anteroposterior, lateral, and open mouth odontoid process view projection) were examined. The distance between the odontoid process and lateral mass of C1, angles of vertical odontoid line and basis of C2 were measured in the ap view. In the lateral view, dorsal alignment and atlantodental distance were assessed. MDCT examinations were used as a reference. Discriminatory power test was applied to assess significance.

Results: 8/79 (10.1 %) odontoid process fractures were found. Diagnosis was achieved on conventional radiographs in 6 patients. Neither distance and angle measurements between odontoid and C1 nor the dorsal alignment of the vertebral bodies differed significantly between healthy and affected patients.

Conclusion: Decentralization of the odontoid process is not necessarily an indirect sign for its fracture. In patients with suspected injury of the odontoid process, an MDCT scan might be the method of choice to rule out a fracture.

Key points:

• Due to the wide physiological variety of odontoid process position, even a detailed metric analysis of cervical alignment and odontoid process angulation in X-ray scans is not able to facilitate the diagnosis of odontoid process fractures.

• In the case of cervical spine trauma, which necessitate medical imaging, a primary MDCT scan should be the method of choice.

Citation Format:

• Keller S., Bieck K., Karul M. et al. Lateralized Odontoid in Plain Film Radiography: Sign of Fractures? – A Comparison Study with MDCT. Fortschr Röntgenstr 2015; 187: 801 – 807

Zusammenfassung

Ziel: Die Evaluation der Wertigkeit von konventionell-radiologischen Messungen zur Detektion einer Densfraktur im Vergleich zur Schnittbildgebung (CT).

Material und Methoden: 79 Patienten (männlich 31, weiblich 48, Alter 60 ± 26 Jahre), die aufgrund einer Lateralisation des Dens axis im konventionellen Röntgen (a. p./lat. Projektion und Denszielauf-nahme) eine CT-grafische weiterführende Untersuchung der Halswirbelsäule erhielten, wurden ausgewertet. Dabei wurden verschiedene Messparameter wie die atlantodentale Distanz, Winkelmessungen zur Evaluation einer Densangulierung und die Beurteilung des Hinterkantenalignements C0-C3 in den o. g. Projektionen im Vergleich zur CT der HWS als Standard ausgewertet. Die statistische Auswertung zur Beurteilung signifikanter Unterschiede zwischen gesunden Patienten und Patienten mit CT-grafisch gesicherter Densfraktur erfolgte mit dem Discriminatory power Test.

Ergebnisse: 8 von 79 (10,1 %) der untersuchten Patienten wiesen eine Fraktur des Dens axis auf. In 6 Patienten wurde die Fraktur bereits im konventionellen Röntgen gesichert. Weder Messungen der atlantodentalen Distanz (Denszielaufnahme 0,49 ± 0,13 cm vs. 0,47 ± 0,13 cm, lat. 0,16 ± 0,09 cm vs. 0,12 ± 0,09 cm), noch die Winkelmessungen (Denszielaufnahme 87,4 ± 2,8° vs. 83,8 ± 3,5° lat. 88,5 ± 6,2° vs. 88,6 ± 6,3°) oder die Evaluation des Wirbelkörperalignements zeigten signifikante Unterschiede zwischen den gesunden Patienten und den Patienten mit Densfraktur.

Schlussfolgerung: Die Dezentralisierung des Dens axis im konventionellen Röntgen bei Patienten mit Verdacht auf eine Densfraktur ist aufgrund der großen physiologischen Variabilität kein sicheres Zeichen für eine Fraktur. Bei klinischem Verdacht auf eine Densfraktur ist eine native Computertomografie der HWS das Mittel der Wahl.

Kernaussagen:

• Auch die metrische Evaluation des zervikalen Alignements und der physiologischen Deviation des Dens axis im konventionellen Röntgenbild ermöglicht keinen sicheren Frakturausschluss.

• Bei HWS-Traumata die eine Bildgebung erfordern ist weiterhin ein primäres MDCT indiziert.

Key words

spine - trauma - CT - radiography

• References

• 1 Pratt H, Davies E, King L. Traumatic injuries of the c1 / c2 complex: computed tomographic imaging appearances. Curr Probl Diagn Radiol 2008; 37: 26-38
• 2 Clark CR, White 3rd AA. Fractures of the dens. A multicenter study. J Bone Joint Surg Am 1985; 67: 1340-1348
• 3 Greene KA et al. Acute axis fractures. Analysis of management and outcome in 340 consecutive cases. Spine (Phila Pa 1976) 1997; 22: 1843-1852
• 4 Chutkan NB, King AG, Harris MB. Odontoid Fractures: Evaluation and Management. J Am Acad Orthop Surg 1997; 5: 199-204
• 5 Anderson LD, D'Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am 1974; 56: 1663-1674
• 6 Elgafy H et al. Treatment of displaced type II odontoid fractures in elderly patients. Am J Orthop (Belle Mead NJ) 2009; 38: 410-416
• 7 Mulkens TH et al. Comparison of low-dose with standard-dose multidetector CT in cervical spine trauma. AJNR Am J Neuroradiol 2007; 28: 1444-1450
• 8 Kim DH et al. Early predictive value of supine and upright X-ray films of odontoid fractures treated with halo-vest immobilization. Spine J 2008; 8: 612-618
• 9 Holmes JF, Akkinepalli R. Computed tomography versus plain radiography to screen for cervical spine injury: a meta-analysis. J Trauma 2005; 58: 902-905
• 10 Davis JW et al. The etiology of missed cervical spine injuries. J Trauma 1993; 34: 342-346
• 11 Reid DC et al. Etiology and clinical course of missed spine fractures. J Trauma 1987; 27: 980-986
• 12 Gerrelts BD et al. Delayed diagnosis of cervical spine injuries. J Trauma 1991; 31: 1622-1626
• 13 Albrecht RM et al. Evaluation of cervical spine in intensive care patients following blunt trauma. World J Surg 2001; 25: 1089-1096
• 14 Grossman MD et al. National survey of the incidence of cervical spine injury and approach to cervical spine clearance in U. S. trauma centers. J Trauma 1999; 47: 684-690
• 15 Harris MB et al. Evaluation of the cervical spine in the polytrauma patient. Spine (Phila Pa 1976) 2000; 25: 2884-2891 discussion 2892
• 16 Bono CM et al. Measurement techniques for upper cervical spine injuries: consensus statement of the Spine Trauma Study Group. Spine (Phila Pa 1976) 2007; 32: 593-600
• 17 Heller JG, Carlson GD. Odontoid Fractures. In: Spine State of the Art Reviews. Philadelphia, Pennsylvania: Hanley and Belfust Inc; 1991
• 18 Platzer P et al. Clearing the cervical spine in critically injured patients: a comprehensive C-spine protocol to avoid unnecessary delays in diagnosis. Eur Spine J 2006; 15: 1801-1810
• 19 Herzenberg JE et al. Emergency transport and positioning of young children who have an injury of the cervical spine. The standard backboard may be hazardous. J Bone Joint Surg Am 1989; 71: 15-22
• 20 Sun PP et al. Spectrum of occipitoatlantoaxial injury in young children. J Neurosurg 2000; 93: 28-39
• 21 Barrett TW et al. Injuries missed by limited computed tomographic imaging of patients with cervical spine injuries. Ann Emerg Med 2006; 47: 129-133
• 22 McCulloch PT et al. Helical computed tomography alone compared with plain radiographs with adjunct computed tomography to evaluate the cervical spine after high-energy trauma. J Bone Joint Surg Am 2005; 87: 2388-2394
• 23 Penrose LS. Measurement of pleiotropic effects in phenylketonuria. Annals of eugenics 1951; 16: 134-141
• 24 Bono CM et al. Observer variability of radiographic measurements of C2 (axis) fractures. Spine (Phila Pa 1976) 2010; 35: 1206-1210
• 25 Rojas CA et al. Normal thickness and appearance of the prevertebral soft tissues on multidetector CT. AJNR Am J Neuroradiol 2009; 30: 136-141
• 26 Van Goethem JW et al. Imaging in spinal trauma. Eur Radiol 2005; 15: 582-590
• 27 Harrison DE et al. Cobb method or Harrison posterior tangent method: which to choose for lateral cervical radiographic analysis. Spine (Phila Pa 1976) 2000; 25: 2072-2078
• 28 Radcliff KE et al. Comprehensive computed tomography assessment of the upper cervical anatomy: what is normal?. Spine J 2010; 10: 219-229
• 29 Widder S et al. Prospective evaluation of computed tomographic scanning for the spinal clearance of obtunded trauma patients: preliminary results. J Trauma 2004; 56: 1179-1184
• 30 Schleehauf K et al. Computed tomography in the initial evaluation of the cervical spine. Ann Emerg Med 1989; 18: 815-817
• 31 Vandemark RM. Radiology of the cervical spine in trauma patients: practice pitfalls and recommendations for improving efficiency and communication. Am J Roentgenol Am J Roentgenol 1990; 155: 465-472