Optical performance and drilling forces of an orthopaedic DRS drill with a stagnant optical probe (Article)

Abstract

In spinal surgery, the misplacement of spinal screws is a common problem that causes (severe) pain, bleedings or even paralysis [1] [2] [3]. In order to improve the navigational support of spine surgeons, this research focuses on the development of an optical sensing diffuse reflectance spectroscopy (DRS) orthopaedic drill that identifies bone tissue boundaries, based on fat fraction. The developed drill concept introduces a stagnant optical fiber-equipped probe into a cannulated orthopaedic drill. To verify the clinical applicability of the developed system, the accuracy of the optical tissue boundary detection has been analysed under different tissue penetration speeds, as well as the axial drilling force increases due to the introduction of a stagnant probe into a cannulated drill. The maximum feed rate at which the drill consistently detects the tissue boundary before breaching it, is 0,5mm/s. The force increase due to the introduction of a stagnant probe is a factor 2,96 on average and varies widely between different feed rates and probe diameters (a factor 1,15–5,75). The established feed rate speed limit of 0,5mm/s is lower than drilling feed rates of up to 5mm/s, observed in the operation room. Increasing the sampling frequency –especially decreasing the inactive period between the measurements– is required. The feed force increase of approximately a factor 3 can be regarded as a challenge for surgeons, who indicated that they preferred feed forces to be kept low.