Diffuse reflectance spectroscopy for breach detection during pedicle screw placement: a first in vivo investigation in a porcine model

Abstract

Background: The safe and accurate placement of pedicle screws remains a critical step in open and minimally invasive spine surgery, emphasizing the need for intraoperative guidance techniques. Diffuse reflectance spectroscopy (DRS) is an optical sensing technology that may provide intraoperative guidance in pedicle screw placement. Purpose: The study presents the first in vivo minimally invasive procedure using DRS sensing at the tip of a Jamshidi needle with an integrated optical K-wire. We investigate the effect of tissue perfusion and probe-handling conditions on the reliability of fat fraction measurements for breach detection in vivo. Methods: A Jamshidi needle with an integrated fiber-optic K-wire was gradually inserted into the vertebrae under intraoperative image guidance. The fiber-optic K-wire consisted of two optical fibers with a fiber-to-fiber distance of 1.024 mm. DRS spectra in the wavelength range of 450 to 1600 nm were acquired at several positions along the path inside the vertebrae. Probe-handling conditions were varied by changing the amount of pressure exerted on the probe within the vertebrae. Continuous spectra were recorded as the probe was placed in the center of the vertebral body while the porcine specimen was sacrificed via a lethal injection. Results: A typical insertion of the fiber-optic K-wire showed a drop in fat fraction during an anterior breach as the probe transitioned from cancellous to cortical bone. Fat fraction measurements were found to be similar irrespective of the amount of pressure exerted on the probe (p = 0.65). The 95% confidence interval of fat fraction determination was found in the narrow range of 1.5-3.6% under various probe-handling conditions. The fat fraction measurements remained stable during 70 min of decreased blood flow after the animal was sacrificed. Discussions: These findings indicate that changes in tissue perfusion and probe-handling conditions have a relatively low measureable effect on the DRS signal quality and thereby on the determination of fat fraction as a breach detection signal. Conclusions: Fat fraction quantification for intraoperative pedicle screw breach detection is reliable, irrespective of changes in tissue perfusion and probe-handling conditions.

Fluoroscopy-Assisted C1–C2 Posterior Fixation for Atlantoaxial Instability: A Single-Center Case Series of 78 Patients

“…The Pediguard, an electronic conductivity device (SpineGuard, Paris, France) designed to assist in pedicle screw placement, has also been used to avoid VAI in fluoroscopy-assisted cadaveric procedures [38,39]. Diffuse Reflectance Spectroscopy is an optical technique which has been experimentally integrated into a surgical device to detect impending cortical breach during pedicle screw placement [40,41]. The continued evolution of percutaneous minimally invasive techniques for cervical fixation procedures will depend on navigation solutions as well as supportive technologies such as those mentioned above.…”

Preclinical evaluation of Raman spectroscopy for pedicular screw insertion surgical guidance in a porcine spine model

“…In principle, successful placement of pedicle screws could be achieved by ensuring that the screws always remain within bone structures during insertion, guaranteeing a strong bond and no breach of the bone surface, thereby limiting fracture risk and damage to adjacent soft tissues. This approach has been investigated using various optical techniques, including near-infrared (NIR) spectroscopy, diffuse reflectance spectroscopy, and photoacoustic imaging 16 – 18 However, each of these relies essentially on a single predictive parameter (e.g., absorbance or elastic scattering, impedance) to differentiate bone from non-bone, which can limit the specificity of tissue identification.…”

“…Practical implementation of RS guidance for placing pedicle screws could take the form of fiberoptic sensors mounted at the tip of a Kirshner wire, trocar, drill bit, screws, or other intramedullary rods 16 , 30 . Such technology integration is in progress by us and other groups developing, for example, low-noise rotary fiber optic joints 31 .…”

“…This approach has been investigated using various optical techniques, including near-infrared (NIR) spectroscopy, diffuse reflectance spectroscopy, and photoacoustic imaging. 16 – 18 However, each of these relies essentially on a single predictive parameter (e.g., absorbance or elastic scattering, impedance) to differentiate bone from non-bone, which can limit the specificity of tissue identification. Moreover, these techniques can be susceptible to failure in cases where nominal specificity is degraded by, for example, intraoperative bleeding.…”

Perspective on the integration of optical sensing into orthopedic surgical devices

“…The full potential of photonic sensing in orthopedic surgery has not been explored but over the past few years there have been some developments for specific procedures and to refine surgical workflow. Examples include: a cranial perforator based on diffuse reflectance spectroscopy (DFS) that stops automatically at the dura, 25 an intramedullary nail system with a DFS sensor 26 that prevents overdrilling, and a pedicle screw insertion device with DFS guidance 27 – 30 that facilitates spinal fixation. Although the first of these devices is used by neurosurgeons, the technology is relevant to orthopedic surgery, since similarly the objective is to avoid perforation through bone into critical adjacent normal tissues structures.…”