| Purpose :(1)Long bone fracture is a common disease in orthopaedics.For the treatment of long bone fracture,TSF has achieved great success in clinic.However,there are some problems in the practical application of TSF,such as the complexity of parameter measurement and the large error of parameter measurement.In this paper,a method of fracture reduction is proposed by using medical three-dimensional image reconstruction and recognition technology,which avoids the complex and limited parameter measurement operation,in order to effectively improve the accuracy of instrument recognition and fracture reduction.The accuracy and validity of the method were tested by model experiments and clinical trials.(2)TSF have the installation constraints of orthogonal proximal ring and proximal bone,fixed six-link connection hole,but it is often difficult to meet the above requirements due to various factors such as clinical patients' position and the arrangement of bone needles.Through the analysis of three-dimensional space kinematics,the installation constraints of fixed rings are removed,and the stable connection mode of the support structure and the installation range of six connecting rods are extended through the analysis of velocity matrix,in order to form a method to avoid various installation constraints and reduce the difficulty of clinical operation of TSF.(3)To verify the accuracy and convenience of this method through clinical trials,and to provide a basis for further clinical promotion.Methods :(1)Aiming at the problem that the existing TSF has complex measurement process and large measurement error in adjusting the required parameters,this paper presents a method of automatically identifying the space state of the support by installing markers,designs a marker which can be loaded and unloaded quickly and easily recognized automatically,and proposes an algorithm for establishing the support coordinate system with few input parameters,which effectively avoids the operation of manual measurement parameters.Reduce the errors introduced by traditional methods in measurement and planning.The feasibility and accuracy of this method are verified by computer simulation,model experiment and clinical trial.(2)Nine cases of tibia and fibula fracture treated with the proposed method were collected from the Department of Traumatic Orthopaedics,Tianjin Hospital from January 2017 to December 2018.After reduction,standard X-ray films of the affected limbs were taken to evaluate the residual displacement and angle after reduction of fracture deformity,and statistical analysis was made.(3)The kinematics model of TSF scaffold and bone fragments is established based on the typical STEWART mechanism by using the method of robotic mechanism analysis.By using the principle of rigid kinematics coordinate transformation,the device installation constraints required by the existing TSF scaffold supporting software are removed.The stability of the six-link non-standard installation of the scaffold is judged by the condition number of velocity Jacobian matrix.To reduce the difficulty of clinical operation of TSF,the installation constraints of less stents and the installation range of connecting rods are enlarged.Results :(1)Computer simulation experiments,model experiments and clinical experiment show that the new recognition and planning method can accurately identify and reposition fractures.In computer simulation experiments,the recognition accuracy were translation 0.0026±0.0963 mm,0.0098±0.1262 mm,0.0023±0.0537 mm,and angulation were 0.0017±0.0398 °,0.0004±0.0408 °,0.0015±0.0871°.In the model experiment,all the fracture stick models(15 cases)achieved good reduction results,which far exceeded the standard of functional reduction.After reduction,the residual displacement,angulation deformity and improvement were 0.59 ±0.47 mm(89.55%),0.83 ±0.49 °(83.23%)and 0.39 ±0.41 mm(91.61%)0.95±0.48 °(73.97%)on the positive and lateral X-ray film respectively.The residual deformities before and after reduction were significantly reduced,and the difference was statistically significant(P<0.05).In clinical trials,all patients(9 cases)with fracture achieved good reduction results,which were far beyond the standard of functional reduction.The residual displacement,angulation deformity and improvement degree in the positive and lateral radiographs after reduction were 1.09 ±0.58 mm(79.12%),1.32 ±0.99 °(76.80%)and 1.04 ±0.93mm(82.58%),0.69±0.37 °(79.52%)respectively.The residual deformities before and after reduction were significantly reduced(P < 0.05);(2)The new three-dimensional kinematics analysis method reduces the constraints on the installation of TSF bracket devices,and provides the basis for judging the stability of the six-link installation,which is the Jacobian matrix condition number.When the TSF bracket is installed clinically,the relative free installation of the fixed ring,the connecting rod and the fracture site can be realized on the premise of the stability of the six-link installation,which effectively reduces the installation require of TSF reducing the Difficulty of Clinical Operation.(3)The planning method proposed in this paper has high reset accuracy and is easy to operate. |
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