Spine Surgery Set-Up

A detailed understanding of surgical anatomy is essential in anterior cervical spine surgery to prevent unintentional damage to critical structures such as the esophagus, vertebral artery, spinal cord, and nerve roots, which are closely located to the surgical site.

While knowledge of anatomy remains paramount, the emerging method of stereotactic intraoperative imaging can support surgeons during cervical spine procedures.

Stereotactic intraoperative imaging is especially beneficial in situations where typical anatomical reference points are absent or modified due to factors such as deformities, trauma, revision surgery, morbid obesity, or ossification of the posterior longitudinal ligament.

This technique provides real-time imaging throughout the surgical procedure, assisting the surgeon in navigating intricate anatomical structures, achieving accurate instrument placement, and reducing the likelihood of complications.

However, it is crucial to emphasize that although stereotactic intraoperative imaging is advantageous, it cannot replace the need for a thorough comprehension of surgical anatomy. Surgeons must have extensive knowledge to ensure the safety and success of anterior cervical spine surgeries.

Stereotactic operations have been used for intracranial surgery since the early 20th century. In spine surgery, computer-assisted navigation emerged in the 1990s. Initially, it relied on frame-based stereotaxis, but advancements now allow for intraoperative imaging and frameless registration. These improvements have made computer-assisted navigation standard in complex anterior cervical spine cases, enhancing accuracy and reducing operative time.

Utilizing intraoperative O-arm navigation facilitates successful and secure performance of minimally invasive anterior transcorporeal foraminotomies and decompressions. It enables the precise extraction of diseased tissue while safeguarding vital anatomical structures. Moreover, this advanced technology enhances the accuracy of screw placement and minimizes radiation exposure for surgeons, surpassing the capabilities of conventional methods

Navigation technology is a useful tool in complex spinal surgeries, but it should not replace the surgeon’s knowledge of anatomy. It should be used as a supportive guide, and confirmation from anatomical landmarks is essential to ensure patient safety.

Approach Stereotactic Navigation

Room Setup

The preferred method for setting up the operating room with stereotactic navigation involves a spacious environment, utilizing a large operative theater to accommodate the O-arm. After patient sedation and intubation, baseline motor functions are established, and the patient is positioned in a supine position with their head secured in a Mayfield 360 head holder. Care is taken to maintain a neutral neck position.

The C-Arm is brought into the room for confirmation of corpectomy location, while the passive reference frame and StealthStation are positioned at the head of the bed. To save space, the O-Arm and Navigation station remain outside the room during C-Arm usage. If the surgeries are scheduled at different times, multiple surgeons can share a single O-arm.

Instruments Equipped With Tracking Technology And The Reference Frame

Reflective spheres are attached to instruments used during the navigated part of the procedure, allowing for optical tracking. The standard instrument set includes a navigated drill and ball-tip probe, with the option to incorporate additional instruments if required. Accurate tracking relies on ensuring the spheres are properly seated, while any interference such as blood or tools can disrupt the tracking process.

To ensure accurate alignment, it is recommended to register the instruments and frame to the StealthStation before attaching the frame. This registration process establishes the spatial relationship between the instruments and frame. It is preferable to perform this registration prior to making the incision to avoid any potential inaccuracies caused by accidental movement when the frame is already attached to the Mayfield head holder.

For optimal use of space during anterior spine exposure, it is suggested to firmly attach the reference array to the Mayfield within a range of 6 to 8 inches from the operative field. This ensures a stable reference position while keeping it away from the surgical area.

To maintain sterility, the non-sterile post is covered with transparent plastic draping, and a small opening is created using scissors to allow for frame insertion. The scissors are subsequently removed from the sterile field.

Method And In-Surgery Spin

Once the frame is attached, the surgical team proceeds with the Smith-Robinson surgical approach. The location of the pathology is confirmed visually and through fluoroscopy. Caspar pins are carefully placed, and distraction is applied. Subsequently, an imaging scan is performed following the approach and Caspar pin distraction.

To prevent tissue desiccation and enhance image quality, the wound is irrigated and left undisturbed. Retracting the soft tissues is essential for accurate imaging. The frame is shielded with surgical drapes, and a sterile towel safeguards it during O-arm closure. Positioning the O-Arm correctly, the green towel is removed before image acquisition commences.

Direct Referencing and Localization

To maintain accuracy, precautions must be taken when removing the protective drape due to the frame’s vulnerability to unintended movement. It is recommended to verify instrument positioning by aligning it with referenced images using a probe on a bony landmark.

If accuracy declines, alternatives include re-registering the system, employing fluoroscopy, or opting for a free-hand technique. Once the imaging scan is completed, the microscope is introduced into the field and remains present throughout the case. Discectomy is performed at both the cranial and caudal levels to aid in subsequent corpectomy.

Screens display images of instruments and the targeted area for the surgeon’s monitoring, while the StealthStation monitor offers supplementary views and trajectory projections managed by the O-arm operator. The corpectomy commences at a designated point, typically the mid-portion of the vertebral body, using a burr. The remaining course of the procedure is determined based on the surgeon’s preference.

Limitations

Although intraoperative stereotactic navigation may not be indispensable or cost-effective for routine procedures, it can offer significant value and dependability for patients with intricate anatomy, severe pathology, or worrisome characteristics.

It is essential to avoid excessive confidence or complacency when utilizing navigation assistance, and regular accuracy checks should be conducted throughout the case. The cervical spine’s flexibility makes it vulnerable to even minor movements that can result in accuracy loss, highlighting the need for verification through anatomical landmarks or fluoroscopy.

The potential drawbacks of this technique, including increased operative time, a learning curve, and disruptions to workflow, should be taken into consideration. However, with an increase in the number of cases and adaptability, these disadvantages can be overcome, as is typical with the introduction of any new technology.

The use of navigation-assisted spine surgery is a developing technology that provides valuable support in a range of spine procedures. This guide is designed to enhance the precision and efficiency of complex anterior cervical spinal surgery. The described technique has been demonstrated to be trustworthy and successful, empowering cervical spine surgeons to undertake more intricate or minimally invasive procedures with heightened levels of safety and accuracy.