Ventral Surgical Approach for an Intervertebral Disc Degeneration and Regeneration Model in Sheep Cervical Spine: Anatomic Technical Description, Strengths and Limitations

Abstract

Objective Sheep are used as a large animal model for intervertebral disc research. However, for the ovine ventral surgical approach to the cervical disc, limited descriptions exist. We, therefore, give a detailed in vivo anatomical description of this approach in sheep for the use in intervertebral disc regeneration and degeneration models to increase the reproducibility of such interventions. Materials and Methods Eighteen female Swiss white alpine sheep, with an age range of 2 to 4 years, were used. A ventral surgical access was performed to establish defined intervertebral disc punch defect from cervical levels C3/4 to C5/6. Cervical levels C2/3 and C6/7 were used as negative controls. Intraoperative findings, radiographical controls and postoperative clinical follow-up were documented and collected for this clinical report. Results All sheep recovered rapidly from the surgical intervention. Two sheep developed wound seroma, which resorbed spontaneously. Two further sheep showed wound dehiscence within 3 days after surgery, which had to be revised. No clinical wound infections occurred and all sheep healed well and did not show any side effects related to the surgical procedure. Conclusion The ventral surgical access to the ovine cervical spine is a safe and reliable procedure. The advantage of the cervical intervertebral disc is the easier surgical access and the increased disc height compared to the sheep lumbar spine. Since the ovine cervical intervertebral disc shows a high grade of similarities (e.g. molecular characteristics) compared to human discs, it is a promising degeneration and regeneration model for disc diseases.

Morphological and biomechanical effects of annulus fibrosus injury and repair in an ovine cervical model

“…Three blinded board‐certified orthopedic surgeons assessed the Pfirrmann grade of each cervical IVD. Disc and vertebral body height was measured by tracing a spline along the cartilaginous endplate with FIJI and calculating the Euclidean distance between the dorsal, central and ventral parts of the spline with a custom Matlab script. Central disc height is presented.…”

The Role of Hyaluronic Acid in Intervertebral Disc Regeneration

“…Several disc degeneration replicas are present to study disc degeneration in in vivo models: spontaneous (genetic aberration induces early disease onset) [89] puncture (physical trauma activating inflammatory response) [90,91] mechanical loading (non-traumatic induction) [92,93] and biochemical (Chondroitinase ABC treatment) [94]. Preclinical models were also used to introduce novel surgical approaches, especially in large animals [95]. Rodent tails have been extensively used to study the pathophysiology of the IVD degeneration and assess the effect of different therapeutics because they are easily accessible with minimal interference with the surrounding tissues and their normal physiological functions [92,93,[96][97][98][99][100][101][102][103][104].…”