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Minimally Invasive Spinal Osteosynthesis

Author: Christian Raftopoulos, Ph.D., M.D., Head of the Neurosurgery Department
University Hospital Saint-Luc in Brussels, Belgium

 

Patient History

An 88-year-old female patient suffered from lower back pain. She was operated on before due to a traumatic fracture of L5 which required cementoplasty.


Diagnosis and Treatment

Spinal instability from L4 – L5 – S1. A spondylolisthesis of L4, L5 and S1 was planned for fixation of the spine under fluoroscopic and 3D image guidance.


Workflow

1. The patient is prepared by the assistant physician and the robot-assisted C-arm is driven interactively. Now the surgeon positions eight fluoroscopy angulations which are considered to be optimal views to implant the six screws, i.e. two screws in each vertebra L4, L5, and S1. At each position a reference image is acquired by the assistant physician and the corresponding position of the C-arm is stored in the robot system to be recalled during the procedure (see Fig. 1a, b). Small incisions are made and the patient is prepared for the placement of K-wires.

2. When the surgeon enters the OR, he recalls the stored C-arm angulations and the robot moves the C-arm automatically and precisely into the corresponding position. No interaction or search for an optimal fluoroscopic view is required, since the robot ensures the exact position as stored by the assistant physician. Thus, no additional X-ray dose is required to find the right angulation. A K- wire is placed under fluoroscopic guidance for each screw position (see Fig. 2).

3. The position of the K-wires is confirmed with intra-operative 3D syngo DynaCT. A low dose syngo DynaCT protocol helps to save dose as the robot arm rotates the C- arm around the patient within five seconds (Fig 3 and 4).

4. In this case, the cement in L5 poses a problem and might lead to instability of the screws. This certain situation forced repositioning one K-wire in order to put the trajectory for the screw more inward and to ensure better stability of the implant (Fig. 4).

5. In order to re-position the K-wire of interest, the surgeon selects on the robot system the position of the C-arm that was stored and associated with this vertebra. The system moves the C-arm into the acquired angulation for an optimal fluoroscopic view (Fig. 5). The corresponding K-wire is re-positioned under fluoroscopic guidance.

6. The final positions of the K-wires are again confirmed by a 3D syngo DynaCT run (Fig. 6 a,b,c).

7. The screws can now be implanted (Fig. 7).

8. Finally, the positions of the screws are reconfirmed by a 3D syngo DynaCT run at the end of the procedure. In general, a standard, post-procedural CT is no longer required because the final position can be confirmed in the OR.

Fig. 1 a, b: Two of the six fluoroscopy images acquired right at the beginning of the intervention. These angulations of the C-arm are considered to be optimal views to implant the screws in the vertebra. For each screw one fluoroscopic image is acquired; in these images a scissor can been seen which is held by the assistant physician and is used to mark the corresponding vertebra for this view. The position of the C-arm that produced this image is stored in the robot system and can be re-visited automatically during the procedure.

Fig. 2: 6 K-wires have been placed under fluoroscopic guidance.

 

Fig. 3: The robot rotates the C-arm within 5 seconds around the patient to acquire a 3D syngo DynaCT image.

Fig. 4: Dr. Raftopoulos verifies the position of the K-wires at the workstation in the OR.


Fig. 5: Dr. Raftopoulos moves the robot into a pre-programmed C-arm angulation which was selected to be an optimal view and stored by his assistant physician right before the intervention.

Fig. 6a,b: Three orthogonal slices of a 3D syngo DynaCT image. These images help to confirm the exact position of the Kwires before implanting the screws.

Fig. 6c: Three orthogonal slices of a 3D syngo DynaCT image. These images help to confirm the exact position of the Kwires before implanting the screws.

 

Fig. 7: In the background, the ceiling-mounted and moveable monitors are shown. The left monitor displays one reference image which was acquired at the beginning of the intervention. Note that besides the image itself, the exact position in which this image was taken is stored by the system. The angulations of the C-arm, and thus the fluoroscopic views, are exactly the same for the images on both monitors.

Comments

During the procedure, the surgeon moves the robot into the exact position of the reference image without any user interaction, which enables him to acquire current fluoroscopic images from exactly the same position seen on the right monitor in Fig. 7. In this way, the surgeon can directly compare the anatomy at the beginning of the procedure in the reference image with the actual anatomy in the live fluoro image on the right monitor. Note that the angulations of the C-arm and, thus, the fluoroscopic views are exactly the same for the images on both monitors. Intraoperative 3D imaging with syngo DynaCT can help to confirm the accurate position of the pinnacle screws and to visualize special anatomical structures or artifacts due to prior interventions. It can re-ensure the correct progress of the intervention and might indicate necessary adjustments right in the OR. The unique robotic drive of Artis zeego allows surgeons to store specific fluoroscopic views which can be re-called during the procedure. This reduces both manual interaction and error, and speeds up considerably the workflow in the OR without losing flexibility. Initial experience with this workflow suggests that the OR time can be halved using Artis zeego.

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Date: Feb 03, 2012


Angiography - Case Studies

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