Percutaneous laser discectomy guided with stereotactic computer-assisted surgical navigation.

BACKGROUND AND OBJECTIVE

Percutaneous laser discectomy at various wavelengths has been used for minimally invasive surgery of herniated intervertebral discs. Using a high-intensity diode laser at 980-nm wavelength, we aimed to improve the safe insertion of the laser trocar with the aid of a stereotactic computer-assisted surgical navigation system.

STUDY DESIGN/MATERIALS AND METHODS: The experiments were performed on ex vivo porcine spines with intact soft tissue. Before laser irradiation, each specimen was imaged by computed tomography (CT) with fiduciary markers. The Digital Imaging and Communications in Medicine (DICOM standard) data sets were retrieved into the GE Healthcare Surgery InstaTRAK3500 Plus computer-assisted surgical navigation platform via the hospital Ethernet using a picture archiving and communication system. A special trocar with quartz waveguide connected to the navigation system was inserted into a total of 12 lumbar discs of two fresh intact porcine specimens. Various laser energies (200-700 J) with different exposure times were delivered. Pre- and post-irradiation magnetic resonance (MR) imaging and postoperative macroscopic and histologic studies were carried out.

RESULTS

A navigation system accuracy of better than 2 mm was achieved. Tracking of the instrument from pre-acquired formatted CT reconstructed images reduced overall radiation exposure by limiting the need for continuous intraoperative C-arm fluoroscopy. The use of surgical navigation by CT images enhanced the precision insertion of the laser trocar. Irradiation with the 980-nm wavelength diode laser resulted in tissue evaporation changes of the intervertebral disc material as demonstrated by comparing pre- and post-irradiation changes of MR images and macro- and microscopic changes of the dissected disc material.

CONCLUSION

This preclinical study demonstrates the clinical utility of a 980-nm diode laser delivered through a fiber-optic waveguide trocar in which precise insertion was enabled by the use of surgical navigation. This in turn decreases the exposure to ionizing radiation during the procedure.