Finding Your Way Around the Spinal Canal: Strategies for Intra-op Implant Placement

This presentation will provide a comprehensive approach to free-hand placement of implants in the vertebral column of dogs and cats. The consequences of poor implant placement can be severe, with the two most common being violation of the spinal canal or foramina, resulting in injury to important neurovascular structures, and inadequate bone purchase, leading to insufficient implant stability. Understanding canine and feline vertebral anatomy is an important prerequisite for spinal fixation. In addition, it is critical to become familiar with the patient-specific anatomy and potential trauma-related changes based on preoperative CT imaging. The time and effort spent on preoperative CT planning will create a roadmap for implant placement that minimizes risk and enhances accuracy during the procedure.
A key aspect of spinal implant placement is identifying anatomic landmarks. While textbook and publication recommendations of implant entry points can serve as a general guide, the surgeon must transfer information from identifiable anatomical points seen on the CT to the visible vertebral surface during surgery. Having an excellent plan on CT is one thing, but transferring it when you are in surgery is another.
Intraoperative CT or image-guided navigation is not commonplace in veterinary surgical practice, which is different from intraoperative X-ray or fluoroscopy. X-rays or fluoroscopy obtained in standard orthogonal planes document overall implant location and angles, and can identify obvious breaches into the intervertebral disk and assess insertion length. However, with diagonally positioned implants, orthogonal views offer poor accuracy in determining implant breach into the spinal canal. End-on fluoroscopy can offer a way to view implants more accurately.
Apart from intraoperative imaging, we will review a variety of surgical techniques that can be used to create and assess drill tunnels, hopefully reducing the risk of spinal canal penetration.