A Safe, Effective, and Economical Protocol for Rabbit Vertebral Screw Insertion

Summary

This article describes a safe, effective, and cost-efficient step-by-step protocol for posterior lumbar screw fixation in New Zealand White rabbits, establishing a standardized approach for vertebral screw insertion in this animal model.

Abstract

Posterior lumbar screw fixation is the most common surgical method for lumbar disc herniation, but patients often face multiple complications postoperatively. The occurrence of screw track loosening can lead to fusion failure and even life-threatening screw track extrusion. However, there is currently a lack of animal models specifically targeting changes in the screw track following lumbar screw fixation. This study developed a vertebral screw insertion method based on New Zealand white rabbits, designed to minimize the risk of postoperative screw penetration into the spinal canal, thus avoiding spinal cord injury. In this protocol, the intersection point of the horizontal line from the upper edge of the transverse process and the junction of the pedicle is recommended as the entry point. The insertion angle should be approximately 45°-55° outward and 20°-40° downward. Additionally, based on screw placement under direct vision and the use of commercial instruments,this method is simpler and more cost-effective compared to existing large animal modeling techniques. It provides an animal model for subsequent basic research on screw track loosening and the microenvironment surrounding the screw track.

Introduction

Lumbar Disc Herniation (LDH) is a common cause of chronic lower back pain and radiating leg pain, particularly in young and middle-aged individuals^1,2,3. The condition usually results from a tear in the annulus fibrosus of the intervertebral disc, leading to the herniation of the nucleus pulposus and compression of the nerve roots^4,5. While many patients benefit from conservative treatments like rest and lifestyle modification, medication therapy, physical therapy, rehabilitation exercises, wearing a brace, and nerve ....

Protocol

The animal experimental protocol was reviewed and approved by the Ethics Committee of Laboratory Animal Welfare and Ethics of the Institute of Radiological Medicine, Chinese Academy of Medical Sciences (Ethics Number: IRM/2-IACUC-2404-005). All handling procedures for the animals complied with the relevant national regulations on animal welfare and ethics.

NOTE: In this study, New Zealand white rabbits were used for experimental investigation. The rabbits were of common grade, weighing approximately 2.5-3.0 kg, aged 3-5 months, and female. The rabbits were housed in a standardized ordinary-grade rabbit room.

Results

Motor function assessment after awakening
Immediately after the rabbit regained consciousness from anesthesia, the motor function of its hind limbs was assessed. It was found that the insertion of the lumbar screw fixation system did not affect the rabbit's motor function (See Supplementary video 1), indicating that the spinal cord was not injured during the procedure.

Micro-CT and X-ray evaluation
To investigate the exact position of .......

Discussion

The most severe complication of posterior lumbar screw fixation (PLF) is the potential for spinal cord injury caused by the screw penetrating the spinal canal during insertion¹⁰. The most critical aspect of this method is the exposure of the transverse process and pedicle, as well as the angle at which the screws are inserted. Adjusting the insertion angle can prevent the screw from entering the spinal canal and causing spinal cord injury. Additionally, due to the anatomical characteristics of the.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
CTAn	BURKER		used in anaylsis
Datviewer	BURKER		used in anaylsis
Micro-CT	BURKER		used in anaylsis
New Zeland Rabbit Pentobarbital	Tianjin Yuda Laboratory Animal Breeding Co., Ltd. Beijing Jiehui Biotechnology Co. MCE		used in this research
pedicle screws	Hebei Ruihe Medical Equipment Co., Ltd	532003510	used in Surgical Procedure
penicillin	MCE	HY-17591R	used in Postoperative Care
Pentobarbital	Beijing Jiehui Biotechnology Co.		used in Anesthesia
rods	Hebei Ruihe Medical Equipment Co., Ltd	532003510	used in Surgical Procedure
surgical instruments and sutures	Hebei Ruihe Medical Equipment Co., Ltd	532003510	used in Surgical Procedure