Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Sep 25.
doi: 10.1097/BSD.0000000000001922. Online ahead of print.

Perioperative Change in Bone Quality Following Posterior Cervical Fusion and Its Effects on Postoperative Outcomes

Hannah A Levy  1 , Caden Messer  1 , Tissiana Vallecillo  1 , Zachariah W Pinter  1 , Tyler Allen  1 , Harold I Salmons  1 , Sarah Townsley  1 , Karim Nathani  2 , Mohamad Bydon  2 , Jeremy L Fogelson  2 , Benjamin D Elder  2 , Bradford Currier  1 , Ahmad N Nassr  1 , Brett A Freedman  1 , Brian A Karamian  3 , Arjun S Sebastian  1
Affiliations

Perioperative Change in Bone Quality Following Posterior Cervical Fusion and Its Effects on Postoperative Outcomes

Hannah A Levy et al. Clin Spine Surg. .

Abstract

Study design: Retrospective cohort analysis.

Objective: To determine the effect of long-segment posterior cervical decompression and fusion (PCDF) on perioperative changes in vertebral Hounsfield Units (HUs) and the impact of these changes on radiographic outcomes and fusion status.

Summary of background data: Low preoperative CT HUs have been associated with adverse outcomes after spinal fusion, including hardware complications and reoperation. No existing studies have investigated the preoperative to postoperative change in HUs after cervical spinal fusion. Stress shielding may decrease bone quality within the fusion construct. Whereas, altered junctional loading and increased segmental mobility may precipitate bony hypertrophy in the terminal and adjacent levels.

Methods: All adult patients who underwent C2-T2 PCDF for myelopathy/ myeloradiculopathy at an academic center between 2013 and 2020 were retrospectively identified. Preoperative and postoperative HUs were assessed on axial CT images in the cranial, middle, and caudal C2, C6, T2, and T3 vertebral bodies, outside of the region of instrumentation and artifact by 2 independent reviewers. Paired t test compared preoperative to postoperative changes in HUs. Preoperative and long-term postoperative cervical alignment, fusion, and revision rates were assessed. Univariate and regression analysis compared patient factors and outcomes between groups with perioperative increase versus decrease in vertebral HUs.

Results: One hundred patients were included. The average preoperative to postoperative change in HUs in the C2, C6, T2, and T3 vertebral bodies were -19.80 (P=0.008), -52.63 (P<0.001), 15.15 (P=0.014), and 9.41 (P=0.346), respectively. Perioperative increase in C2 HUs was predictive of increased postoperative distal junctional angle (β=3.41, P=0.048) and increased T1-T4 kyphosis (β=6.50, P=0.003). Perioperative increase in C6 HU predicted pseudoarthrosis (fusion odds ratio: 0.19, P=0.007).

Conclusions: Significant perioperative decreases in C6 HUs within a long-fused construct may demonstrate stress shielding. The significant association between greater distal kyphosis and an increase in C2 HUs may be attributed to a stress riser effect.

Level of evidence: Level III.

Keywords: Hounsfield unit; bone quality; posterior cervical fusion; stress shielding.

PubMed Disclaimer

Conflict of interest statement

Funding and disclosure statement: The authors, their immediate family, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article. All authors significantly contributed to the document and have reviewed the final manuscript. Outside of this manuscript, the following conflict of interests exist: Mohamad Bydon: Consulting Fees- Zimmer, Medtronic, Pacira, Longeviti. Jeremy Fogelson: Consulting Fees- Medtronic. Benjamin Elder: Grants or contracts from any entity- SI bone, Stryker, Board or Committee member- AANS/CNS Spine Section, Congress of Neurological Surgeons, Lumbar Spine Research Society, North American Spine Society, Scoliosis Research Society, PLOS ONE. Bradford Currier: DePuy, A Johnson & Johnson Company: IP royalties, SpinologyTenex: Stock or stock Options, Surgalign: Paid consultant, Wolters Kluwer Health - Lippincott Williams & Wilkins: Publishing royalties, financial or material support, Zimmer: IP royalties. Brett A. Freedman: Ankasa: Research support, AO Spine: Paid presenter or speaker, Clear Choice Therapeutics: Stock or stock Options, Kuros: Paid consultant, Medtronic: Paid consultant; Research support, Neuroinnovations: Stock or stock Options, Synthes: Paid consultant, Theradaptive: Paid consultant. Ahmad Nassr: American Orthopaedic Association: Board or committee member, AO Spine: Research support, Cervical Spine Research Society: Board or committee member, Lumbar spine research society: Board or committee member, Pfizer: Research support, Premia Spine: Research support, Scoliosis Research Society: Board or committee member, Techniques in Orthopedics: Editorial or governing board. Brian Karamian: Clinical Spine Surgery: Editorial or governing board. Arjun Sebastian: Cerapedics: Paid consultant; Paid presenter or speaker, CTL Amedica: IP royalties, DePuy, A Johnson & Johnson Company: Paid consultant, Jaypee Publishers: IP royalties.

References

    1. Sardar ZM, Coury JR, Cerpa M, et al. Best practice guidelines for assessment and management of osteoporosis in adult patients undergoing elective spinal reconstruction. SPINE. 2022;47:128–135.
    1. Diebo BG, Sheikh B, Freilich M, et al. Osteoporosis and spine surgery: a critical analysis review. JBJS Rev. 2020;8:e0160–e0160.
    1. Guzman JZ, Feldman ZM, McAnany S, et al. Osteoporosis in cervical spine surgery. SPINE. 2016;41:662–668.
    1. Deshpande N, Hadi MS, Lillard JC, et al. Alternatives to DEXA for the assessment of bone density: a systematic review of the literature and future recommendations. J Neurosurg: Spine. 2023;38:436–445.
    1. Choi MK, Kim SM, Lim JK. Diagnostic efficacy of Hounsfield units in spine CT for the assessment of real bone mineral density of degenerative spine: correlation study between T-scores determined by DEXA scan and Hounsfield units from CT. Acta Neurochir. 2016;158:1421–1427.

LinkOut - more resources