The new stereotactic guidance system saved time and provided reliable guidance to for determining the needle entry point for discography and consecutive PELD. However, the stereotactic system version 2 requires improvements such as lighter weight and increased reproducibility.
An ideal stereotactic system requires accurate guidance to the target. Factors, such as patient movement during the operation, change of lumbar lordosis in the prone position with different pillow heights, or change in the angle of the fluoroscopic view, may result in a different distance or angle of needle entry.
Previous reports have stated that compared to open surgery, minimally invasive spine surgery (MISS) has great merits, including lower infection rates, more tolerate postoperative pain, and a shorter hospital stay. A drawback of this approach is that multiple fluoroscopic images must be obtained to ensure correct tube positioning; this exposes the surgeon and surgical team to increased doses of ionizing radiation relative to those in traditional open procedures. Surgeons performing minimally invasive operations receive 10 to 22 times more radiation than that received by surgeons performing open operations [5
PELD is a mainstay of MISS. Sufficient analgesia during the surgery makes the patient feel as if it is real MISS. The preferred route of performing PELD is under local anesthesia with intravenous analgesia rather than under general anesthesia, which is accompanied by complicated neural monitoring systems and risks such as accidental extubation or disposition of the endotracheal tube during surgery with the patient in a prone position [6
]. Monitored anesthetic care greatly facilitates to the performance of MISS. Dexmedetomidine ensures cooperative sedation during the operation without the risk of respiratory depression [7
]. Dexmedetomidine is administrated at least 10 minutes before surgery and is titrated intraoperatively to ensure that the patient will be appropriately sedated and will not move during surgery. In addition, a preoperative analgesic patch of 5% lidocaine provides pain relief during PELD, especially at the stages of needle insertion, skin incision, serial dilation and insertion of the working channel, and subcutaneous suture [6
]. During surgery, anular infiltration of 1% lidocaine helps to reduce pain-related motion of the patient unconsciously. Traditionally, intravenous analgesia with local skin infiltration has been used to prevent patient's movement resulting from incisional pain.
To accurately target the HNP, it is important to properly place the needle for discography and subsequent discectomy. A "push and pull technique" is the best and quickest method for a contained HNP based on preoperative MRI evaluation [8
]. "Pushing the HNP into the anterior 1/3 of the disc and then pulling it out" is a simple technique under fluoroscopy with/without endoscopic vigilance. However, both the distance from the midline and the angle from the skin may result in needle entering at a different point based on the direction of herniation in downward or upward migration or to the central, subarticular, foraminal, or extraforaminal zone [4
Many manufactures have produced different types of surgical navigation systems for spine surgery. The main purpose of these systems is to provide an accurate insertion point for the best route to the target organ with minimal destruction of normal tissues. However, the main concerns of using these systems are radiation exposure from using an image-guided navigation system and cost-effectiveness. Most operating rooms do not have adequate space for accommodating these surgical navigation systems.
Thus far, clinical data strongly supporting the use of image-guidance techniques have only been published for pedicle screw implantation in the cervical and lumbar spine [9
]. A major advantage of image-guidance system-based education modules, if systematically used in a lab setting, is that they allow a trial-and-error based educational approach. Interesting developments are expected from the integration of image analysis techniques and endoscopy. Image-guided techniques have reached a high level of development, as the accuracies that can be achieved technically meet the anatomical demands [10
]. Intraoperative CT or MRI is also now available in the surgical field [11
]. The utility of robotics or 3-dimensional CT is determined by cost and time benefits and outcomes of research on both safety and efficacy issues [14
Intraoperative, full-rotation, 3-dimensional image (O-arm) fluoroscopy may help navigation to the targeted organ in spine surgeries or interventions with reduced radiation exposure [16
]. In addition, compared with the use of traditional systems of image acquisition and registration for navigation, the use of the commercially available navigation system with the O-arm system showed a higher accuracy for spinal navigation [18
]. However, during the operation, surgeons are required to operate inside the machine within a limited space.
The great merits of this stereotactic system for PELD include its low cost, easy adaptability for users who are accustomed to the conventional method, and the fact that it does not occupy a large space. For the confirmation of a safe unipedicular vertebroplasty, an imaginary approach line is drawn on the skin using preoperative CT or MRI and a PACS drawing tool [19
]; therefore, this system may be helpful during the use of the unipedicular approach for vertebroplasty, which has a risk of neural damage. However, this system could be improved by smoothing the rotation movement of the K-wires, reducing the weight, and increasing the flexibility.
The new stereotactic guidance system under fluoroscopy is feasible and time-saving experimental design for determining needle entry point during uniplanar fluoroscopy-guided intervention. Therefore, this system may reduce radiation exposure-, which is the main drawback of MISS. However, several limitations of this design, such as heaviness, difficulty in rotation movement, and lack of flexibility, should be overcome.