Unilateral biportal endoscopy (UBE) spine surgery for thoracolumbar intervertebral disc diseases in dogs: An ex vivo cadaveric and in vivo preclinical study.

Abstract

OBJECTIVE: To determine optimal portal position for thoracolumbar unilateral biportal endoscopy (UBE) spine surgery in dogs. STUDY DESIGN: Experimental ex vivo cadaveric and in vivo preclinical study. ANIMALS: Seven cadavers and three healthy purpose-bred Beagles. METHODS: In the ex vivo phase, thoracolumbar mini-hemilaminectomy was performed at T13-L1, L1-L2, and L2-L3 in seven cadavers using two UBE portal positions. The distance (X) from the spinous process to the mammillary process was measured fluoroscopically. Group A portals were placed from X to 2X; Group B portals from 2X to 3X. Visualization and instrument accessibility were compared. Based on cadaveric results, mini-hemilaminectomy was performed in three live dogs using the superior (Group B) portal position. Intraoperative epidural pressure was measured. Postoperative magnetic resonance image (MRI) on day 0, 14, and 28 evaluated muscle recovery, fluid extravasation, and spinal/dural compression. RESULTS: Mini-hemilaminectomy was successfully performed with both portal positions. Surgical time and number of fluoroscopic scans did not differ between groups. Scope insertion angles were steeper in Group B (p&#x2009;<&#x2009;.001), which also showed higher visualization and accessibility scores (p&#x2009;<&#x2009;.001). Group B portals were used in the in vivo study. Epidural pressure remained stable, and MRI revealed transient postoperative muscle edema that resolved by day 28. CONCLUSION: UBE was feasible in cadavers and safe in live dog models. Group B portal positioning provided better visualization and accessibility. CLINICAL SIGNIFICANCE: UBE presents a potential minimally invasive approach for thoracolumbar spinal surgery in dogs.