Novel Calcium Phosphate Promotes Interbody Bony Fusion in a Porcine Anterior Cervical Discectomy and Fusion Model

Maria Östman; Peter Försth; Patricia Hedenqvist; Håkan Engqvist; Leticia Marcelino; Bjørnar Ytrehus; Gry Hulsart-Billström; Michael Pujari-Palmer; Caroline Öhman-Mägi; Odd Höglund; Franck Forterre

doi:10.1097/BRS.0000000000004916

Novel Calcium Phosphate Promotes Interbody Bony Fusion in a Porcine Anterior Cervical Discectomy and Fusion Model

Spine (Phila Pa 1976). 2024 Jan 12. doi: 10.1097/BRS.0000000000004916. Online ahead of print.

Affiliations

¹ Department of Clinical Veterinary Medicine, Division of Small Animal Surgery, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
² Dept of Surgical Sciences, Division of Orthopedics, Uppsala University, Uppsala, Sweden.
³ Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
⁴ Dept of Materials Science and Engineering, Division of Applied Materials Science, Uppsala University, Uppsala, Sweden.
⁵ University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden.
⁶ Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
⁷ Norwegian Veterinary Institute, Ås, Norway.
⁸ Department of Medicinal Chemistry, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.

PMID: 38213106
DOI: 10.1097/BRS.0000000000004916

Abstract

Study design: Experimental porcine anterior cervical discectomy and fusion (ACDF) model: a proof-of-concept study.

Objective: The effect of monetite synthetic bone graft containing calcium pyrophosphate (Ca-PP) and β-tricalcium phosphate (β-TCP) on cervical spinal fusion in a non-instrumented two-level large animal model.

Summary of background data: ACDF is the gold standard surgical technique for the treatment of degenerative cervical spinal diseases. However, pseudarthrosis associated with increased patient morbidity occurs in approximately 2,6% of the surgeries. Synthetic bone graft (SBG) may enhance bony fusion and subsequently decrease the risk of pseudarthrosis. Recent studies on monetite-based synthetic bone grafts for use in large cranial defects in humans have shown promising bone healing results, necessitating further investigation of their use in cervical spinal fusion.

Methods: Four adult female Danish Göttingen mini-pigs received partial cervical anterior discectomy and intervertebral defects at an upper and lower level. One defect was filled with SBG and the other was left empty. Bony fusion was evaluated using computed tomography (CT) at three-month intervals for 12 months. Fifteen months post-surgery, the animals were euthanized for further ex vivo qualitative histopathological and micro-CT evaluations. Fusion rates were compared using Fisher´s exact test at each time point.

Results: Increased interbody bony fusion rates were observed at synthetic bone graft levels (4/4) compared with control levels (0/4) evaluated by CT at 6- and 9-months post-surgery ( P = 0.029). Fusion was observed at all synthetic bone graft levels 12 months post-surgery and at only one control level. Histopathological evaluation confirmed high-quality interbody bony fusion at all synthetic bone graft levels, and fusion by spondylosis at one control level.

Conclusion: This proof-of-concept study provides preliminary evidence of a novel, Ca-PP -and β-TCP-containing monetite SBG that promotes bony fusion compared to a negative control in a clinically relevant porcine model of ACDF.

Level of evidence: N/A.