Quantitative Evaluation And Precise Repair Of Early Acetabular Bone Defect Based On Biomechanical Characteristics

Acetabular bone defect is the main pathological feature of developmental dysplasia of hip,which is a common hip deformity in joint surgery.Serious defect can lead to hip joint disability,which seriously affects the health level of Chinese people.Due to the complex structure of the hip joint,the current understanding of acetabular defects in many aspects is still shallow,and the clinical treatment effect is not satisfactory,so it is necessary to conduct in-depth research on it.Due to the lack of accurate methods and quantitative indicators to evaluate early acetabular defects,the clinical condition of some patients is often inaccurate,which are easy to miss diagnosis and miss the best treatment opportunity.Therefore,it will be helpful to improve the accuracy of diagnosis and treatment to explore the method of accurate assessment of acetabular defect.At present,the harm of acetabular bone defect is unclear,the existing theory is just a general description of the principle of acetabular bone defect damage to the mechanical characteristics of the hip joint,lack of relevant basic data support,the specific relationship between the degree of defect and its mechanical harm is not clear.Therefore,in-depth mechanical research and detailed analysis of the relationship between acetabulum defect and harm can not only provide scientific evidence for the improvement of the above theory,but also be used to evaluate the harm of acetabulum defect,guide the choice of treatment time and method,and improve the treatment effect.The ultimate goal of acetabular defect treatment is to restore the acetabulum to a normal state from the aspects of anatomy and mechanics,but the clinical results show that there is still a gap between the repaired acetabulum and the normal state.In addition to the reasons of surgical technique,the poor curative effect is also related to the fact that surgeons generally pay more attention to anatomy and less to mechanics in the treatment.Due to the lack of mechanical verification methods,it is unknown whether the treated joints have recovered normal mechanical characteristics,which undoubtedly increases the uncertainty and risk of treatment.Moreover,all kinds of osteotomy methods cause different degrees of damage to the original hip bone,so the trauma is large,the risk is high,and the long-term results are not ideal.Therefore,in the process of improving treatment methods,it is necessary to integrate the mechanical factors into the research,and design a method that can not only accurately repair the acetabulum,but also improve the mechanical characteristics,which will be conducive to improving the treatment effect.This dissertation conducts innovative research on early acetabular bone defects from the perspective of biomechanics,finds quantitative methods to evaluate acetabular defects;analyzes the mechanical hazards of acetabular bone defects;and designs and verifies methods for accurate repair of acetabular defects.The details are as follows:(1)A study on quantification of early acetabular defect by LCEABased on the imaging features of acetabular defects,the lateral CE angle(LCEA)was used to evaluate the acetabular defects,and the method of quantitatively dividing the acetabular defects was explored.The optimal quantitative criteria were further determined by layered comparison.The LCEA 5 degree change was set as a quantitative indicator of acetabular defects,and a 5 degree decrease in LCEA angle represented an increase of 2 mm in the acetabular rim defect.It provides a new method for basic research and clinical evaluation of acetabular defects.(2)Effect of early acetabular bone defect on mechanical properties of hip jointThe acetabular defects and normal hip joint models were constructed by reverse engineering software.The three-dimensional finite element method was used to compare the changes of mechanical characteristics of each hip joint under static and dynamic(gait cycle)conditions.The results show that acetabulum defect can increase the stress of hip joint,cause the abnormal distribution of joint stress,local stress concentration and other hazards;the harm of acetabulum defect is related to the degree of defect,which increases with the degree of defect.The specific manifestation is that 2 mm acetabulum defect can increase the stress of standing hip joint by 29%-43%,while 4 mm acetabulum defect can double the stress of joint Therefore,we should carry out clinical intervention as early as possible for acetabular defect;walking will increase the stress of hip joint,and the larger the abduction angle is,the greater the pressure is,so this kind of patients should not walk too long,and the abduction should not be too large;the internal pressure of the femoral head increases,and the stress concentrated,which explains the reason of the cystic necrosis in the clinical femoral head.The stress changes of hip joint before and after 20°LCEA angle are obviously different,so that it may be used as a standard point to judge the severity and prognosis of the disease.The results of this study carefully analyzed the relationship between the defect and the damage,improved the mechanical theory,and provided a scientific basis for the clinical evaluation,as well as the choice of treatment opportunity and methods.(3)Clinical application of accurate repair of acetabular defects based on biomechanical characteristicsCombined with 3D reconstruction,3D printing and finite element technology,the method of precise repair of acetabulum defect was designed,and its effectiveness was verified by mechanics and clinical practice,providing a new choice for clinical treatment.In this study,3D reconstruction technology was used to accurately measure the defect,and then the patch of precise repair of acetabulum defect was designed.The effectiveness of simulated acetabulum repair was verified by finite element test.The results show that there is no statistically significant difference in mechanical parameters between the repaired hip and healthy hip(P>0.05),which proved that the accurate acetabular repair could restore the mechanical characteristics.The 3D printing technology was used to make the solid model of repair patch and hip joint.The results showed that the matching between the components was good,the acetabulum contained the femoral head well after repair,and the combination of the patch and acetabulum was stable,which proved the feasibility of the precise repair method.The clinical data of patients were collected,and the clinical indicators pre and post operation were compared to judge the curative effect.The results showed that the clinical operation was successful,the postoperative imaging,function,gait and other clinical indicators were significantly improved,and the clinical effect was satisfactory.Therefore,the precise repair method designed by the combination of finite element and 3D printing technology was proved to be effective through basic mechanics and clinical practice,and can be used as a new method for the clinical repair of acetabular defects.