| Skeletal system is one of the most important organ systems in the human body and plays an important role in supporting the body.Bone tissue can usually be distinguished as hard bone and cartilage tissue.Because of their excellent mechanical properties,the cutting of bone tissue during surgery is also the most important problem in the medical field.At present,the surgical process using traditional instruments generally has the characteristics of "fine","dangerous","difficult","blind" and "long",which not only lead to the high probability of postoperative complications and long postoperative recovery time,but also put forward higher requirements on the psychological,physical and experience of surgeons.Therefore,it is the most concerned direction of all circles to develop a kind of surgical power instrument with a new mechanism of osteotomy,improve its osteotomy technical system for this device,and realize the real osteotomy therapy innovation.Aiming at the urgent demand for advanced bone cutting technology and high-end orthopedic surgical instruments in the clinical medical field,this paper considers the structural morphology and mechanical properties of hard bone tissue and cartilage tissue respectively,and focuses on the key issues such as fine and low-damage bone tissue resection.Based on the research ideas from the research and breakthrough of the core technology of the equipment to the establishment of the overall design system of the equipment,from the study of the adaptability of bone cutting to the process of bone tissue material removal and surface formation,a new generation of bone cutting surgical instruments and techniques based on the principle of ultrasonic cutting were systematically carried out.Through the innovative design of high performance ultrasonic transducer and the investigation of ultrasonic vibration characteristics,the overall design of ultrasonic bone tissue cutting surgical instruments and the study of bone cutting technology were carried out,the material removal behavior of bone tissue cutting under the action of ultrasonic was defined,and the biological evaluation method of bone tissue after ultrasonic bone cutting was established.Finally,this study basically completed the research on the key technology of ultrasonic bone tissue surgical instruments with fine,low damage and easy operation.The main work of this paper is as follows:Firstly,the performance improvement of ultrasonic transducer is studied from the perspective of structural improvement.Based on the analysis of two bad coupling states,longitudinal coupling and radial coupling,a low coupling elastic flange structure was proposed.Based on the finite element analysis,the structure size of the low coupling flange was optimized,and the measurement system was built.Through the actual measurement,it was found that the proposed and optimized new low coupling flange structure has obvious decoupling ability,which significantly improves the amplitude output of the transducer.This study based on the analysis and discussion of the low coupling flange structure provides structural optimization for the ultrasonic surgical instruments studied in this paper.Then the frequency response control of ultrasonic transducer is studied from the angle of electrical characteristics.The nonlinear characteristics of the ultrasonic transducer are studied according to the phenomena of frequency offset lag and amplitude steepness.By fitting the measured free vibration attenuation process of the ultrasonic transducer,it is found that both the equivalent mechanical loss and the equivalent spring constant are linearly related to the amplitude of vibration velocity.Based on this,an equivalent circuit model of the piezoelectric transducer is established.Based on the circuit model,a nonlinear model containing quadratic nonlinear terms describing the nonlinear vibration behavior of the transducer is proposed.The numerical results verify the effectiveness of the nonlinear model and show that the model can well describe the typical nonlinear phenomena of the transducer under high power excitation.The measurement of the nonlinear parameters further shows that this model is helpful to predict the nonlinear characteristics of the ultrasonic transducer and a nonlinear tuning control strategy is proposed based on this.The overall design process of ultrasonic hard bone surgical instrument was improved,and the tissue biological evaluation method of ultrasonic bone tissue cutting was defined.A kind of ultrasonic cutting tool is designed for bone cutting,and according to the principle of bone cutting,a special bending tool is designed,which can realize the transverse swing vibration.Impedance analysis and frequency response measurement proved that the resonant frequency and amplitude of the proposed ultrasonic hard bone surgical instrument met the design requirements.The results of in vitro cutting experiment and histological analysis of pig leg bone showed that the ultrasonic hard bone surgical instrument could remove bone tissue accurately and safely,and create good healing conditions for postoperative recovery.The results of animal experiments on mice showed that compared with the defects caused by traditional instruments,the developed ultrasonic hard bone surgical instrument was beneficial to the postoperative recovery of bone defects.A systematic study was carried out on the removal behavior of bone tissue material with ultrasonic hard bone surgical instrument.Based on the understanding of ultrasonic bone resection and structure,four cutting modes of material removal behavior in ultrasonic hard bone surgical instrument were defined according to the size of ultrasonic amplitude and the full consideration of more microscopic bone tissue structure.They are respectively Transverse-Parallel cutting mode(TP mode),Transverse-Intersect cutting mode(TI mode)and Vertical-Cross cutting mode(VC mode)),Vertical-Intersect cutting mode(VI mode)).Through ultrasonic osteotomy experiments under different cutting modes,the process of ultrasonic osteotomy was defined and the removal behavior of bony tissue materials under ultrasonic action was revealed.The effects of different cutting modes on the invasion depth,material removal,surface morphology and cutting force were expounded,and the mechanism of bone chip formation and crack propagation was preliminarily investigated.The ultrasonic cartilage tissue surgical instrument(referred to as ultrasonic cartilage aspirator)was initially developed,and the overall design process was described.At the same time,the basic experiment of cartilage tissue cutting was carried out.According to the basic structure and characteristics of cartilage tissue,elliptic ultrasonic vibration was introduced into cartilage cutting.Based on the finite element design method and the principle of vibration superposition,the basic design process and control method of the end-face elliptic ultrasonic transducer were proposed.Impedance analysis and frequency response measurement were used to verify the performance of the instrument and the formation and control of elliptical ultrasound.The basic experiment of in vitro cutting of mouse costal cartilage was carried out with the designed ultrasonic cartilage attractor,which proved that the device can effectively remove cartilage.Histological section analysis showed that the ultrasonic cartilage aspirator could effectively reduce the damage to the surrounding tissue and create good conditions for the healing after surgery,and the removal of cartilage tissue under the action of ultrasonic was preliminarily realized. |
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