Dynamic cervical flexion/extension atlantodental interval and functional outcome of the Harms technique for posterior C1/2 fixation: A retrospective analysis of 16 atlantoaxial subluxation cases in a tertiary medical center

M-L Su; Z-H Liu; P-H Tu; Y-C Huang

doi:10.1016/j.neuchi.2021.10.003

Dynamic cervical flexion/extension atlantodental interval and functional outcome of the Harms technique for posterior C1/2 fixation: A retrospective analysis of 16 atlantoaxial subluxation cases in a tertiary medical center

Neurochirurgie. 2022 Feb;68(2):168-174. doi: 10.1016/j.neuchi.2021.10.003. Epub 2021 Nov 10.

Authors

M-L Su¹, Z-H Liu², P-H Tu², Y-C Huang³

Affiliations

¹ Department of Neurosurgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Neurosurgery, Taipei Medical University Hospital, Taipei, Taiwan.
² Department of Neurosurgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan.
³ Department of Neurosurgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan. Electronic address: ns3068@gmail.com.

PMID: 34774580
DOI: 10.1016/j.neuchi.2021.10.003

Abstract

Background: The aim of this study was to assess the relationship between the atlantodental interval (ADI) on dynamic flexion/extension cervical radiographs and functional outcomes of posterior spinal fixation by the Harms technique for atlantoaxial subluxation (AAS). Dynamic flexion/extension on cervical radiographs is a standard assessment for evaluation of C1/2 instability in AAS patients. Most studies focused on postoperative ADI and functional outcome, including pain and fusion rate; only few studies compared dynamic ADI change pre- to post-operatively.

Material and methods: Retrospectively, we reviewed the medical records of 16 patients who underwent posterior spinal fixation in our center from 2018 to 2019. We used dynamic cervical flexion/extension radiographs to assess the pre- to postoperative change at 12 months in ADI of flexion (ADI_f), ADI of extension (ADI_e), ADI between flexion/extension (ADI_Δ), C1/2 fusion rate and functional outcomes measured by the modified Japanese Orthopaedic Association scale (mJOA scale). Postoperative CT at 3∼12 months assessed screw positioning on the Gertzbein and Robbins classification.

Results: In the 16 patients included in this study, ADI_f, ADI_e and ADI_Δ were significantly reduced, from respectively 8.0mm, 5.0mm and 3.0mm preoperatively to 4.6mm, 3.8mm and 0.8mm at 12 months' follow-up. The fusion rate was 81% and the mJOA score recovery rate was 34.9±14.7%. Although the screw malposition rate was higher than in other studies in C1(10%) and C2(20%), there were no new neurologic deficits or worsening of symptoms at follow-up.

Conclusions: The ADI_Δ showed significant reduction, showing that the Harms technique of posterior spinal fixation can effective in maintaining the stability of the atlantoaxial joint and improving functional outcome.

Keywords: Atlantoaxial subluxation; Atlantodental interval; C1 lateral mass-C2 pedicle screw fixation; C1–2 harms technique; Radiological measurement.

MeSH terms

Atlanto-Axial Joint* / diagnostic imaging
Atlanto-Axial Joint* / surgery
Cervical Vertebrae / diagnostic imaging
Cervical Vertebrae / surgery
Humans
Joint Instability* / surgery
Retrospective Studies
Spinal Fusion*
Treatment Outcome