Biomechanical evaluation of 2 insertion points for ventral screw fixation of C-2 dens fractures

Laboratory investigation

Restricted access

Object

For many Type II fractures of the dens (Anderson and D'Alonzo classification), a double anterior screw fixation is performed. If screw disruption occurs, the location is most often at the anterior caudal endplate and body of the axis and not directly at the fracture line. The authors' objective was to determine the differences in primary mechanical stability at 2 insertion points used in ventral screw fixation of Type II fractures of the C-2 dens.

Methods

Screw fixation was performed on 16 formalin-fixed human C-2 dens specimens. The specimens were divided into 2 groups. For Group 1, the screws were inserted directly at the anterior lower endplates; for Group 2, the screws were inserted 2 mm dorsal to the anterior wall of the vertebral body. After a Type II odontoid fracture was created with an oscillating saw, screw fixation was performed using two 3.5-mm partially threaded lag screws with washers. Subsequently, each vertebral body was continuously loaded. The criterion for breakage was reversal of the force vector.

Results

In Group 1, screw disruption occurred at the point of entry; the mean load failure was 290.5 ± 106 N. In Group 2, no screw disruption occurred; the mean load failure was 574.2 ± 170.5 N. These results were significant (p < 0.05).

Conclusions

For double screw fixation of Type II fractures of the dens (Anderson and D'Alonzo classification), placement of the screws as far dorsal to the anterior lower endplate as possible seems to favorably affect primary stability. In actual clinical practice, care should be taken to not damage the anterior wall of the vertebral body of the axis during screw insertion.

Article Information

Address correspondence to: Ludwig Oberkircher, M.D., Department of Trauma, Hand and Reconstructive Surgery, Philipps University Marburg, Baldingerstrasse, D-35043 Marburg, Germany. email: oberkirc@med.uni-marburg.de.

Please include this information when citing this paper: published online April 5, 2013; DOI: 10.3171/2013.3.SPINE12745.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Intraoperative images after screw fixation, lateral views. A: Group 1 (point of insertion directly at the anterior lower endplate). B: Group 2 (point of insertion 2 mm dorsal to the anterior lower endplate). Insertion points are marked by arrows.

  • View in gallery

    Intraoperative images after screw fixation of a previously generated Type II fracture according to the Anderson and D'Alonzo classification. A: Anteroposterior view. B: Lateral view.

  • View in gallery

    Vertebral body being subjected to load by an Instron 5566. The maximum pressure point was at the midpoint of the dens.

  • View in gallery

    Interruption of loading after reversal of the force vector. A: Group 1 (point of insertion directly at the anterior lower endplate). The screws are clearly breaking loose ventrally at the base of the body of the axis. B: Group 2 (point of insertion 2 mm dorsal to the anterior lower endplate). Note there is no fracture at the ventral wall of the axis.

  • View in gallery

    Mean load failure, in newtons, of the different insertion points. *p < 0.05.

References

  • 1

    Aebi MEtter CCoscia M: Fractures of the odontoid process. Treatment with anterior screw fixation. Spine (Phila Pa 1976) 14:106510701989

  • 2

    Agrillo ARusso NMarotta NDelfini R: Treatment of remote type ii axis fractures in the elderly: feasibility of anterior odontoid screw fixation. Neurosurgery 63:114511512008

  • 3

    Alfieri A: Single-screw fixation for acute Type II odontoid fracture. J Neurosurg Sci 45:15182001

  • 4

    Anderson LDD'Alonzo RT: Fractures of the odontoid process of the axis. 1974. J Bone Joint Surg Am 86-A:20812004

  • 5

    Apfelbaum RILonser RRVeres RCasey A: Direct anterior screw fixation for recent and remote odontoid fractures. J Neurosurg 93:2 Suppl2272362000

  • 6

    Böhler J: Anterior stabilization for acute fractures and nonunions of the dens. J Bone Joint Surg Am 64:18271982

  • 7

    Campanelli MKattner KAStroink AGupta KWest S: Posterior C1–C2 transarticular screw fixation in the treatment of displaced type II odontoid fractures in the geriatric population— review of seven cases. Surg Neurol 51:5966011999

  • 8

    Chang KWLiu YWCheng PGChang LSuen KLChung WL: One Herbert double-threaded compression screw fixation of displaced type II odontoid fractures. J Spinal Disord 7:62691994

  • 9

    Chi YLWang XYXu HZLin YHuang QSMao FM: Management of odontoid fractures with percutaneous anterior odontoid screw fixation. Eur Spine J 16:115711642007

  • 10

    Denaro VPapalia RDi Martino ADenaro LMaffulli N: The best surgical treatment for type II fractures of the dens is still controversial. Clin Orthop Relat Res 469:7427502011

  • 11

    Dickman CASonntag VKHPapadopoulos SMHadley MN: The interspinous method of posterior atlantoaxial arthrodesis. J Neurosurg 74:1901981991

  • 12

    Dunn MESeljeskog EL: Experience in the management of odontoid process injuries: an analysis of 128 cases. Neurosurgery 18:3063101986

  • 13

    Eysel PRoosen K: [Ventral or dorsal spondylodesis in dens basal fracture—a new classification for choice of surgical approach.]. Zentralbl Neurochir 54:1591651993. (Ger)

  • 14

    Greene KADickman CAMarciano FFDrabier JBHadley MNSonntag VK: Acute axis fractures. Analysis of management and outcome in 340 consecutive cases. Spine (Phila Pa 1976) 22:184318521997

  • 15

    Hanssen ADCabanela ME: Fractures of the dens in adult patients. J Trauma 27:9289341987

  • 16

    Harms JMelcher RP: Posterior C1–C2 fusion with polyaxial screw and rod fixation. Spine (Phila Pa 1976) 26:246724712001

  • 17

    Heggeness MHDoherty BJ: The trabecular anatomy of the axis. Spine (Phila Pa 1976) 18:194519491993

  • 18

    Henry ADBohly JGrosse A: Fixation of odontoid fractures by an anterior screw. J Bone Joint Surg Br 81:4724771999

  • 19

    Ivancic PCBeauchman NNMo FLawrence BD: Biomechanics of halo-vest and dens screw fixation for type II odontoid fracture. Spine (Phila Pa 1976) 34:4844902009

  • 20

    Julien TDFrankel BTraynelis VCRyken TC: Evidence-based analysis of odontoid fracture management. Neurosurg Focus 8:6e12000

  • 21

    Maak TGGrauer JN: The contemporary treatment of odontoid injuries. Spine (Phila Pa 1976) 31:11 SupplS53S602006

  • 22

    Magee WHettwer WBadra MBay BHart R: Biomechanical comparison of a fully threaded, variable pitch screw and a partially threaded lag screw for internal fixation of Type II dens fractures. Spine (Phila Pa 1976) 32:E475E4792007

  • 23

    Penning L: Normal movements of the cervical spine. AJR Am J Roentgenol 130:3173261978

  • 24

    Platzer PThalhammer GOstermann RWieland TVecsei VGaebler C: Anterior screw fixation of odontoid fractures comparing younger and elderly patients. Spine (Phila Pa 1976) 32:171417202007

  • 25

    Sasso RDoherty BJCrawford MJHeggeness MH: Biomechanics of odontoid fracture fixation. Comparison of the one- and two-screw technique. Spine (Phila Pa 1976) 18:195019531993

  • 26

    Schatzker JRorabeck CHWaddell JP: Fractures of the dens (odontoid process). An analysis of thirty-seven cases. J Bone Joint Surg Br 53:3924051971

  • 27

    Vaccaro ARMadigan LEhrler DM: Contemporary management of adult cervical odontoid fractures. Orthopedics 23:110911152000

  • 28

    Ziai WCHurlbert RJ: A six year review of odontoid fractures: the emerging role of surgical intervention. Can J Neurol Sci 27:2973012000

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