A Study of Bone Thickness Measurement by Using Infrared Sensor for Pedicle Screw Insertion

Pedicle Screw was used for spinal fixation since 1944 by King. There are several techniques were used for pedicle screw placement purpose. The common technique used by the surgeon was free hand and image guided technique. For the deepness measurement of pedicle screw insertion, it depends on a palpation of doctor to judge the boundary between the cortex and cancellous bone. This technique still has a possibility to give an error (e.g. misplacement of screw and injury) in surgical processes due to the subjective judgment. The existing bone thickness and screw dimension can be determined preoperatively using imaging procedures (CT Scan) which is off-line technique. This paper was discussed a new technique for measurement of bone thickness by using an infrared sensor. Three specimens were used in this study and the result showed that it has a good relationship between bone thickness and amount of light that received by an infrared sensor. This technique has high possibility to detect different bone thicknesses.