偵測多根骨科螺釘鎖緊力之被動式射頻辨識檢測系統

Abstract

椎弓根螺釘常見於骨科脊椎融合手術中，以固定椎骨的方式使患者椎骨癒合。椎骨癒合效果與螺釘的固定狀況有直接關係。因手術後椎骨融合需要一段時間，所以目前臨床上都在手術後六至八週內才依患者不同狀況進行不同的X光檢測，檢查患者的椎骨融合狀況，而椎弓根螺釘若在這段期間內發生鬆動，無法以X光照片準確的判斷，因此有很大的機率會使癒合的效果不如預期，並且不適合密集的多次檢查，因為需考量患者累積承受的輻射劑量。 本實驗室於104、105年度已提出可偵測多根骨科固定螺絲鬆緊度之被動無線感測裝置，藉由共振頻率的偏移量，得知螺釘的鎖緊力。多組感測裝置需多組天線，容易使天線產生互相干擾的現象，造成量測結果的偏移。當無線量測中間的介質有肌肉組織時，會造成其量測結果的共振頻率偏移，以及降低其量測距離。在實際應用上，不同患者肌肉組織的厚度與組成成分不盡相同，而有肌肉組織造成量測上的偏移將會有隱憂，因此具有改善的空間。 本研究提出一結合量測電路、射頻辨識與使用者介面等多項系統整合之偵測多組可變電阻(替代感測器)被動式射頻辨識檢測系統。此系統整合是藉由射頻辨識標籤的微控制器，處理多組感測器，能使用一組天線搭配三組感測器，大幅減少多組天線互相干擾的現象。而數位化量測結果來進行無線通訊，有效避免量測結果受肌肉組織干擾。結合手機顯示與操作功能，使此系統擁有即時檢測(POCT)、無線感測網路(WSN)與物聯網(IoT)之大數據潛力。希望本研究未來能幫助醫生更有效率的掌握患者術後狀況，並在螺絲發生鬆動時能盡早處理，提高患者骨科脊椎融合手術後之癒合品質。

Pedicle screws are common in the orthopedic spinal fusion surgery, which are used to fix the vertebrae of the patients for healing. The effect of vertebrae healing is directly related to the fixation of screws. Due to postoperative vertebral fusion requires a period of time, according to the different conditions of the patients in the six to eight weeks after the surgery, doctors decide the different X-ray detection to check the patient’s status of the vertebral fusion. If the pedicle screws are loosening within the six weeks, it won’t be discovered by X-ray detection, but there is a high probability to reduce the healing effect. Furthermore, the X-ray detection is not suitable for intensive examination, because the radiation dosimetry of the patients must be concerned. Our laboratory has been proposed Passive wireless sensors for tightness monitoring at different locations on orthopedic fixation screw system in 2016 and 2017. The locking force of the screw is known by the offset of the resonance frequency. In this system, because of multiple sensing devices with multiple antennas, the antennas are easy to produce interference with each other, which makes the measurement results offset. When the medium of the wireless measurement including the muscle tissue, it will make the measurement results of the resonant frequency offset and reduce the measurement distance. In practical applications, the muscle tissue thickness and composition are not the same in different patients, so that the problem of the resonant frequency offset by the medium including the muscle tissue need to be solved. This research proposes a passive RFID measurement system for detecting multiple variable resistors, which is integrated with the measurement circuit, RFID and user interface. The sensing tag of one antenna can process three variable resistors by the microcontroller, which can reduces the interference of the multiple antennas. Digitizing the measurement results for wireless communication can effectively reduce the effect of the muscle tissue interference. Integrating the display and operating functions of the smart phone make this system produce the potential of big data including Point of Care Testing(POCT), Wireless Sensor Network(WSN) and Internet of Thing(IoT). In the future, this research will help doctors more effectively understand the status of the postoperative patients, make some emergency response as soon as possible when they find out the loosening screws and improve the quality of postoperative vertebral fusion for patients.