Diffuse reflectance spectroscopy of the spine: improved breach detection with angulated fibers

Abstract

Accuracy in spinal fusion varies greatly depending on the experience of the physician. Real-time tissue feedback with diffuse reflectance spectroscopy has been shown to provide cortical breach detection using a conventional probe with two parallel fibers. In this study, Monte Carlo simulations and optical phantom experiments were conducted to investigate how angulation of the emitting fiber affects the probed volume to allow for the detection of acute breaches. Difference in intensity magnitude between cancellous and cortical spectra increased with the fiber angle, suggesting that outward angulated fibers are beneficial in acute breach scenarios. Proximity to the cortical bone could be detected best with fibers angulated at θ f = 45 ∘ for impending breaches between θ p = 0 ∘ and θ p = 45 ∘ . An orthopedic surgical device comprising a third fiber perpendicular to the device axis could thus cover the full impending breach range from θ p = 0 ∘ to θ p = 90 ∘ .

Seeing from a new angle: design of a sideways-looking fiber-optic probe to advance spine surgery

“…5(a)-(c)) may be attributed to a refractive index mismatch causing specular reflection. 12 This phenomenon is absent for forward light collection in a parallel breach scenario (Fig. 5(d)), where the detector is not facing the interface.…”

“…Netherlands), and a top layer simulating cancellous bone made from pure coconut milk with 19% fat (Thai Agri Foods Public Company Limited, Bang Sao Thong, Thailand). 12 Breach experiments In the initial set of experiments, the probe's forward sensing capabilities were tested in a perpendicular breach scenario. The probe was oriented perpendicular to the interface of the two phantom layers and mounted onto a manual 25 mm linear translation stage equipped with an optical stage position encoder (Thorlabs Inc., Newton, NJ, USA).…”

“…11 To cover the full range of impending cortical breaches whilst keeping the complexity of the probe low and minimizing the amount of fibers used, the probed volume can be manipulated with obliquely oriented collecting fibers. 12 Collecting light both along the device axis ("forward") as well as perpendicularly ("sideways") allows to examine the tissue ahead of and lateral to the probe tip to avoid both perpendicular and parallel breaches. To overcome spatial constraints for fiber angulation in medical devices, sideways collection is enabled by slanted optical fibers, which can be coated with silver or gold to maximize the collected intensity.…”

Usefulness of a drill stopper to prevent iatrogenic soft tissue injury in orthopedic surgery

“…Shubert et al and Gonzalez et al devised a method using ultrasound- and photoacoustic-guided fiber optic drilling to avoid critical structures and impending cortical breaches during pedicle screw insertion for spinal fusion surgery [ 14 , 15 ]. In a similar attempt, Losch et al introduced diffuse reflectance spectroscopy-guided pedicle screw insertion during spinal surgery [ 16 ].…”

Fiber-Optic Pedicle Probes to Advance Spine Surgery through Diffuse Reflectance Spectroscopy

“…Optical sensing has emerged as a promising approach for tissue feedback, offering directed measurements to provide insights into tissue composition and structure. In this context, Diffuse Reflectance Spectroscopy (DRS) has been proven to provide tissue feedback for spine surgery in a non-harmful way [9][10][11]. The reflectance spectra result from the interplay of light scattering and absorption by tissue constituents within the probed region.…”