Pedicle or lateral mass screws in Goel-Harms construct? A biomechanical analysis.

BACKGROUND The use of the posterior arch of C1 as pedicle has shown beneficial stability regarding screw loosening, however, the C1 pedicle screw placement is challenging. Therefore, the study aimed to analyse the bending forces of the Harms construct used in fixation of C1/C2 when using pedicle screws compared to lateral mass screws. METHODS Five cadaveric specimens with a mean age of 72 years at death and bone mineral density measuring for 512.4 Hounsfield Units (HU) on average were used. A custom-made biomechanical setup was used to test the specimens with a C1/C2 Harms construct each with the use of lateral mass screws and pedicle screws in sequence. Strain gauges were used to analyse the bending forces from C1 to C2 in cyclic axial compression (μm/m). All underwent cyclic biomechanical testing using 50, 75 and 100 N. FINDINGS In all specimens, placement of lateral mass screws and pedicle screws was feasible. All underwent cyclic biomechanical testing. For the lateral mass screw, a bending of 142.04 µm/m at 50 N, 166.56 µm/m at 75 N and 188.54 µm/m at 100 N was measured. For the pedicle screws, bending force was slightly elevated with 165.98 µm/m at 50 N, 190.58 µm/m at 75 N and 195.95 µm/m at 100 N. However, bending forces did not vary significantly. In all measurements, no statistical significance was found when comparing pedicle screws and lateral mass screws. INTERPRETATION The lateral mass screw used in the Harms Construct to stabilize C1/2 showed less bending forces, therefore the construct with lateral mass screws appears more stable in axial compression compared to the one with pedicle screws. However, bending forces did not vary significantly.

[1]  T. Albert,et al.  Bone Density Distribution in the Cervical Spine , 2022, Global spine journal.

[2]  S. You,et al.  Hounsfield unit measurement method and related factors that most appropriately reflect bone mineral density on cervical spine computed tomography , 2022, Skeletal Radiology.

[3]  L. Müller,et al.  Locking suture repair versus ligament augmentation—a biomechanical study regarding the treatment of acute lateral collateral ligament injuries of the elbow , 2022, Archives of Orthopaedic and Trauma Surgery.

[4]  M. Scheyerer,et al.  Suggestion of a safe zone for C1 pedicle screws depending on anatomical peculiarities , 2021, European Spine Journal.

[5]  L. Müller,et al.  The role of the brachialis muscle in elbow stability with collateral ligament injury: A biomechanical investigation. , 2021, Clinical biomechanics.

[6]  L. Müller,et al.  The effect of glenoid lateralization and glenosphere size in reverse shoulder arthroplasty on deltoid load: A biomechanical cadaveric study. , 2021, Journal of orthopaedics.

[7]  P. Eysel,et al.  The role of the transversal ligament on the atlantoaxial complex - Bending forces at C1/2 flexion limits in the elderly. , 2021, Clinical biomechanics.

[8]  O. Danisa,et al.  Measurement Techniques and Utility of Hounsfield Unit Values for Assessment of Bone Quality Prior to Spinal Instrumentation: A Review of Current Literature , 2019, Spine.

[9]  R. Hurlbert,et al.  Management of Odontoid Fractures in the Elderly: A Review of the Literature and an Evidence-Based Treatment Algorithm , 2018, Neurosurgery.

[10]  S. Batra,et al.  Morphometric Study of C1 Pedicle and Feasibility Evaluation of C1 Pedicle Screw Placement with a Novel Clinically Relevant Radiological Classification in an Indian Population , 2017, Asian spine journal.

[11]  S. Mirza,et al.  C2 Vertebral Fractures in the Medicare Population: Incidence, Outcomes, and Costs. , 2016, The Journal of bone and joint surgery. American volume.

[12]  C. Matthiessen,et al.  Epidemiology of atlas fractures--a national registry-based cohort study of 1,537 cases. , 2015, The spine journal : official journal of the North American Spine Society.

[13]  G. Huber,et al.  Biomechanical advantage of C1 pedicle screws over C1 lateral mass screws: a cadaveric study , 2014, European Spine Journal.

[14]  D. Hao,et al.  Is the 4 mm height of the vertebral artery groove really a limitation of C1 pedicle screw insertion? , 2014, European Spine Journal.

[15]  D. Gelb,et al.  Biomechanical comparison of the pullout strengths of C1 lateral mass screws and C1 posterior arch screws. , 2013, The spine journal : official journal of the North American Spine Society.

[16]  B. Chang,et al.  Routine insertion of the lateral mass screw via the posterior arch for C1 fixation: feasibility and related complications. , 2012, The spine journal : official journal of the North American Spine Society.

[17]  R. Fessler,et al.  An alternate method for placement of C-1 screws. , 2010, Journal of neurosurgery. Spine.

[18]  S. You,et al.  Troublesome occipital neuralgia developed by c1-c2 harms construct. , 2008, Journal of Korean Neurosurgical Society.

[19]  M. Murphy,et al.  Evaluation of morbidity, mortality and outcome following cervical spine injuries in elderly patients , 2008, European Spine Journal.

[20]  S. Zhong,et al.  Anatomic Considerations for the Pedicle Screw Placement in the First Cervical Vertebra , 2005, Spine.

[21]  D. Resnick,et al.  Anatomic Suitability of the C1-C2 Complex for Pedicle Screw Fixation , 2002, Spine.

[22]  J. Harms,et al.  Posterior C1–C2 Fusion With Polyaxial Screw and Rod Fixation , 2001, Spine.

[23]  L. Anderson,et al.  Fractures of the odontoid process of the axis. 1974. , 1974, The Journal of bone and joint surgery. American volume.

[24]  T. Sui,et al.  Comparison of perpendicular to the coronal plane versus medial inclination for atlas pedicle screw insertion: an anatomic and radiological study in human cadavers , 2015, International Orthopaedics.