The direct lateral approach is an alternative to the transoral or endonasal approaches to ventral epidural lesions at the lower craniocervical junction. In this study, the authors performed, to their knowledge, the first in vitro biomechanical evaluation of the craniovertebral junction after sequential unilateral C1 lateral mass resection. The authors hypothesized that partial resection of the lateral mass would not result in a significant increase in range of motion (ROM) and may not require internal stabilization.
The authors performed multidirectional in vitro ROM testing using a robotic spine testing system on 8 fresh cadaveric specimens. We evaluated ROM in 3 primary movements (axial rotation [AR], flexion/extension [FE], and lateral bending [LB]) and 4 coupled movements (AR+E, AR+F, LB + left AR, and LB + right AR). Testing was performed in the intact state, after C1 hemilaminectomy, and after sequential 25%, 50%, 75%, and 100% C1 lateral mass resection.
There were no significant increases in occipital bone (Oc)–C1, C1–2, or Oc–C2 ROM after C1 hemilaminectomy and 25% lateral mass resection. After 50% resection, Oc–C1 AR ROM increased by 54.4% (p = 0.002), Oc LB ROM increased by 47.8% (p = 0.010), and Oc–C1 AR+E ROM increased by 65.8% (p < 0.001). Oc–C2 FE ROM increased by 7.2% (p = 0.016) after 50% resection; 75% and 100% lateral mass resection resulted in further increases in ROM.
In this cadaveric biomechanical study, the authors found that unilateral C1 hemilaminectomy and 25% resection of the C1 lateral mass did not result in significant biomechanical instability at the occipitocervical junction, and 50% resection led to significant increases in Oc–C2 ROM. This is the first biomechanical study of lateral mass resection, and future studies can serve to validate these findings.
AR = axial rotation; E = extension; F = flexion; LAR = left AR; LB = lateral bending; Oc = occipital bone; RAR = right AR; ROM = range of motion.
Correspondence Varun R. Kshettry: Cleveland Clinic, Cleveland, OH. email@example.com.
INCLUDE WHEN CITING Published online October 1, 2021; DOI: 10.3171/2021.4.SPINE21226.
Disclosures Callan M. Gillespie: received royalties from CCF/simVITRO. Robb W. Colbrunn: received royalties from simVITRO-Cleveland Clinic. Michael P. Steinmetz: received royalties from Zimmer/Biomet and Elsevier; consultant for Globus and Stryker; received honoraria from Medtronic and Globus. Varun R. Kshettry: consultant for Integra and Stryker.
Morales-ValeroSF, SerchiE, ZoliM, Endoscopic endonasal approach for craniovertebral junction pathology: a review of the literature. Neurosurg Focus. 2015;38(4):E15.10.3171/2015.1.FOCUS1483125828491)| false
PanjabiMM, OdaT, CriscoJJIII, Experimental study of atlas injuries. I. Biomechanical analysis of their mechanisms and fracture patterns. Spine (Phila Pa 1976).1991;16(10)(suppl):S460–S465.180125310.1097/00007632-199110001-00001)| false
KshettryVR, HealyAT, ColbrunnR, et al.Biomechanical evaluation of the craniovertebral junction after unilateral joint-sparing condylectomy: implications for the far lateral approach revisited. J Neurosurg. 2017;127(4):829–836.
KshettryVR, HealyAT, ColbrunnR, Biomechanical evaluation of the craniovertebral junction after unilateral joint-sparing condylectomy: implications for the far lateral approach revisited. J Neurosurg. 2017;127(4):829–836.10.3171/2016.7.JNS1629327739941)| false
TechyF, MageswaranP, ColbrunnRW, Properties of an interspinous fixation device (ISD) in lumbar fusion constructs: a biomechanical study. Spine J. 2013;13(5):572–579.10.1016/j.spinee.2013.01.04223498926)| false
PanjabiM, DvorakJ, CriscoJIII, Flexion, extension, and lateral bending of the upper cervical spine in response to alar ligament transections. J Spinal Disord. 1991;4(2):157–167.10.1097/00002517-199106000-000051806080)| false