| dc.description.abstract | In recent years, implantation surgery has been widely used from dental implants to implantation of limbs, amputations, facial features, etc. Clinically, it is generally believed that the postoperative osseointegration (implant stability) is the basis for judging the success of the operation. This research develops an osseointegration detection device for lower limb amputation implants, and design related simulation scenarios based on limb implantation surgery procedures, establish effective evaluation methods by providing objective quantitative values through this device, assist physicians in immediate treatment and reduce the risk of surgical failure.
Lower limb implant knocks into femur, can be considered as cantilever structure. The better the rigidity of the cantilever beam, the stronger the rigidity around it, the higher the resonance frequency; otherwise, the lower the resonance frequency. This device inputs 200 to 10k Hz AC wavelet signal to the laminated type actuator coil, make it produce exchanged magnetic force to excite the magnetic fitting above the implant, and make it vibrate. Based on the Hall effect, the magnetic field passes through a linear Hall element to generate an induced electromotive force. After the Hall voltage of the probe group and the reference group is calculated by the frequency response function, to get the resonance frequency of the structure, judge the degree of osseointegration accordingly.
It is important to develop a detection device and confirm its specifications, the device uses the excitation coil as the excitation source, according to the standard in Chapter 3, the DFE322512C laminated excitation coil was finally selected. Using linear Hall elements as response measurement elements, select the applicable Hall element according to the noise ratio in Chapter 2, finally choose WSH135 this Hall element. And discuss the oxide metal film resistance RSF2WS in the designed circuit, to prevent the resistor from consuming too much power and causing the device case to melt, the driving voltage of this device is 1 volt, generates 0.1 watts of power consumption. After element selection, calculated the detection device sensitivity is 0.48 mV/mA, in the frequency response range, the system error value is 0.90%.
Using the femur of the hindlimb of Nubian goat as the experimental object, use different proportions of epoxy resin and glass fiber powder to simulate different stages of osseointegration, and make magnetic accessories NCUpeg, and compare Osstell® magnetic accessories Smartpeg. In Smartpeg measurement, the resonance frequency is high frequency (9k Hz), the numerical simulation results show that the implant only vibrates locally at the top; In NCUpeg measurement, the resonance frequency is low frequency (1.3k Hz), the numerical simulation results are the overall vibration of the implant and goat femur. In order to reflect the overall proliferation of bone between the femur and the implant, so choose NCUpeg as the accessory. Bone block design: (1) Initial stability after implantation; (2) the growth of cortical bone cells during rehabilitation; (3) At 6 months after implantation, osseointegration is almost complete. Regardless of the measurement results in any direction, the interface structure is the highest resonance frequency of epoxy resin and 30% glass fiber powder (Young′s coefficient 5.1 GPa), and without any interface, tissue resonance frequency is the lowest. This result confirms that the stronger the rigidity around the implant, the resonance frequency is higher, the measurement results also conform expectations.
The goal of this device is to simplify the circuit design to achieve reduced size and handheld, perform a series of specification verifications on the designed device, compare Smartpeg and NCUpeg, and compare the numerical simulation results, NCUpeg can show the actual state of osseointegration. The development of this device hopes to provide physicians as an evaluation tool for various stages of treatment, building a more complete treatment plan, and improve surgical effectiveness. Expect this device as an important part of the limb implantation procedure in the future.
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