Diffuse reflectance spectroscopy-enhanced drill for bone boundary detection

Abstract

Intramedullary nailing is a routine orthopedic procedure used for treating fractures of femoral or tibial shafts. A critical part of this procedure involves the drilling of pilot holes in both ends of the bone for the placement of the screws that will secure the IM rod to sections of the fractured bone. This step introduces a risk of soft tissue damage because the drill bit, if not stopped in time, can transverse the bone-tissue boundary into the overlying muscle, causing unnecessary injury and prolonging healing time due to periosteum damage. In this respect, detecting the bone-tissue boundary before breakthrough can reduce the risks and complications associated with intramedullary nailing. Hence, in the present study, a two-wavelength diffuse reflectance spectroscopy technique was integrated into a surgical drill to optically detect bone-tissue boundary and automatically trigger the drill to stop. Furthermore, Monte-Carlo simulations were used to estimate the maximum distance from within the bone at which the bone-tissue boundary could be detected using DRS. The simulation results estimated that the detection distance, termed the "look-ahead-distance" was ∼1.5 mm for 1.3 mm source-detector fiber separation. Experimental measurements with 1.3 mm source-detector fiber separation showed that the look-ahead-distance was in the order of 250 µm in experiments with set drill rate and in the range of 1 mm in experiments where the holes were drilled by hand. Despite this difference, the automated DRS enhanced drill successfully detected the approaching bone tissue boundary when tested on samples of bovine femur and muscle tissue.

Perspective on the integration of optical sensing into orthopedic surgical devices

“…This approach has been demonstrated with other optically enabled surgical devices. 25 , 26 In addition to challenges similar to those in total hip arthroplasty, the screws and drill depth for medial clavicle fixation are relatively short, typically in adults. 31 One technical challenge, which is found across all the applications, is selecting the optimum optical properties for differentiating bone from surrounding soft tissues, especially where there may be vessel or nerve adhesions to the bone.…”

“…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.…”

Cranial Perforation Using an Optically-Enhanced Surgical Drill

“…In a similar manner to that previously described in [16], the DRS sensing was integrated into a modified version of a commercial surgical drill (CD4, Stryker, USA) presented in Figure 1a. The most critical modifications of the drill involved the integration of 18 photodiodes (PDs) into the drill's chuck and optical fibers inside the CP burr.…”

“…This study illustrates the potential of integrating DRS-based optical guidance into a surgical tool. More specifically, this first attempt employed two wavelengths, 530 nm and 850 nm, to detect the boundary between cranial bone and the underlying brain by dynamically measuring the changes in diffuse reflectance as suggested by the previous, related study [16]. To date, there has been a limited number of studies investigating optical integration into surgical tools for direct measurements and surgical guidance [17], [18], [26].…”

“…DRS has proved very useful in quantifying important information related to physiological properties of the tissue such as chromophore concentration or microstructure and has thus helped in the identification of tissue type [14], [15]. Recently, it has also been demonstrated that DRS can be used for controlling the drilling depth in orthopedic procedures [16]. In this biophotonics approach, differences in the optical properties of bone and blood-filled muscle were utilized to detect the boundary between the two tissue types in real time, while drilling through the bone.…”