| BackgroundDevelopmental dislocation of the hip is a common disease in total hip replacement surgery in China with a high relative rate.Total hip arthroplasty,as an effective treatment for adult DDH,has been widely used in surgery,and the anatomic placement of a prosthesis to establish a hip rotation center has been widely recognized clinically,but many biomechanical researches and academic views on Crowe type ? DDH patients in what location on earth hip rotation center reconstruction is still controversial,in addition,finite element biomechanical analysis under different conditions of dual hip health and pathological changes has not been reported at home and abroad,On the one hand,is there a difference in the follow-up results of DDH patients after THA under different conditions of hip health and lesion on the opposite side of replacement?on the other hand,health or disease the contrary hip under different conditions of Crowe type ? DDH patients is biomechanical differences?which is the necessary problem and urgent theoretical support that clinicians must consider when performing total hip replacement for DDH patients.Based on this,the clinical data of DDH patients with complete follow-up in THA in our hospital were retrospectively analyzed to determine the initial clinical effect of the replacement of the contralateral hip under different conditions of health and pathological changes,also as to provide theoretical basis for clinical doctors put prosthesis,the three dimensional finite element analysis of biomechanics analysis from 1 clinical case of Crowe type ? DDH patients CT data model was used to explore the corresponding structure stress distribution around the hip joint and to make clear the hip under different conditions and different hip rotation center position reconstruction in compressive stress situation of the structure.Part oneThe initial clinical observation based on the contralateral hip conditions of DDH patients underwent THAObjectiveThe short-term and mid-term clinical effects of developing mental dysplasia of hip(DDH)on anatomical reconstruction of acetabular rotation center in patients with Crowe ??? were analyzed retrospectively under different conditions of hip health or pathological changes.MethodsFrom February 2010 to February 2018 in our hospitals 102 cases of primary total hip replacement(118 hips)of patients with clinical and imaging data were retrospectively analyzed,including the male 47 and female 55 cases,the contralateral hip replacement healthy subjects(according to Tonnis grade of stage 0?1),a total of 42 cases(male 18,female 24),the replacement of the contralateral hip lesions((according to Tonnis grade of stage 2?3)in patients with 60 cases(23 cases of male,the female 37 cases).They were aged from 32 to 71,with an average age of 66.3 years.Harris hip scoring system was used to evaluate the clinical effect before and after surgery.The position of false weight was evaluated according to X-ray and CT.Relevant indicators of postoperative follow-up were recorded and analyzed in patients with different conditions of hip health and disease on the contralateral side of replacement.Results1.Patients of Crowe ??? DDH underwent THA when the contralateral hip were health,acetabulum center of rotation in the anatomy of a mild off shift(11±4 mm)cases postoperative follow-up results of each index have no statistical difference,but 15 mm up anatomical location,the postoperative hip abductor strength decreased significantly and the mortar wear degree is bigger;In patients with>15 mm lower anatomical position,the improvement time of patients with postoperative claudication was significantly prolonged(mean 4.5±1.5 months).2.Patients of Crowe ???DDH underwent THA when the contralateral hip were lesions,acetabulum center of rotation in the anatomy of a mild off shift(11±4 mm),the postoperative follow-up results were obvious differences in indexes.3.When the acetabulum center of rotation of patients with Crowe ? DDH has not been anatomically reconstructed,the postoperative observation indexes have no obvious difference in short-term(<5 years)follow up,but the difference is obvious after mid-term follow up(>5 years).ConclusionsCrowe ??? DDH patients whoever undergo THA can achieve satisfactory short-term and medium-term clinical efficacy in an anatomically reconstruction of the rotation center of the acetabulum,however,when the contralateral hip was in different conditions health or lesion,the reconstruction deviated from the anatomical position showed great differences not only in the follow-up results of>5 years,but also in the postoperative mechanical performance of the bilateral hip in these two states,which should be proved by further experimental analysis.Part twoFinite element analysis of THR based on the contralateral hip conditions of Crowe ? DDH patientsObjectiveUsing three dimensional finite element analysis technology to explore the stress conditions of adult Crowe type ? DDH when the contralateral hip was health or lesions with different prosthesis position of rotation center,and then to provide theoretical reference for clinical prosthesis position.Methods1.Finite element mechanical analysis of different reconstruction centers of acetabular rotation during the replacement of the health contralateral hipRandomly selected 1 case Crowe ? DDH patients'CT data who underwent THA with the contralateral hip was health to model simulate and analysis.The experiment was divided into four groups for comparison and analysis.In group 1A,the rotation center of the hip was anatomically located,group 1B the rotation center was deepened and internal displacement from anatomical place(internal displacement of 12mm).group 1C shifted down(down 20mm)to reconstruct the rotation center;Upper and outer displacement(upper and outer displacement of 20mm)of group 1D.All of the above changes in the reconstructed position of the rotation center were based on the anatomical position of the true acetabulum as a reference.Four groups of the models were placed in corresponding positions in Magics software.The established models were saved in inp format and imported into ABAQUS 6.14 software for 3d finite element stress analysis.2.Finite element mechanical analysis of different reconstruction centers of acetabular rotation during the replacement of contralateral hip lesions.Using the same patients'CT data to simulate and analysis,but change its position to simulate the lesions contralateral hip.The experiment was divided into four groups for comparison and analysis.In group 2A,the rotation center of the hip was anatomically located,group 2B the rotation center was deepened and internal displacement from anatomical place(internal displacement of 12mm).group 2C shifted down(down 20mm)to reconstruct the rotation center;Upper and outer displacement(upper and outer displacement of 20mm)of group 2D.All of the above changes in the reconstructed position of the rotation center were based on the anatomical position of the true acetabulum as a reference.Four groups of models were placed in corresponding positions in Magics software.The established models were saved in inp format and imported into ABAQUS 6.14 software for 3d finite element stress analysis.Results1.The stress distribution of the heath contralateral hip with different acetabulum rotation center under different conditionsThe maximum Von Mises values of the femur and the prosthesis stem were 6.6MPa and 15.2MPa respectively when internal displaced.The minimum Von Mises values of the femur and the prosthesis stem were 6.0MPa and 12.1MPa,respectively,when the values were shifted outward on the rotation center.The maximum Von Mises value of the sacroiliac joint in the pelvis was 7.5Mpa when the rotation center shifted inward.The minimum Von Mises value is 5.4MPa when the rotation center moves down.The maximum Von Mises value of the prosthesis acetabulum was 3.9Mpa when it was shifted outward on the rotation center.The minimum Von Mises value of the prosthesis socket was 1.Ompa when it was shifted inward in the rotation center.The maximum Von Mises value of the prosthesis lining was 0.6Mpa when the rotation center moved down.The values of Von Mises were the same in the other three experimental groups,with a value of 0.5Mpa.2.The stress distribution of the lesions contralateral hip with different acetabulum rotation center under different conditionsThe maximum Von Mises values of the femur and the prosthesis stem were 6.9MPa and 13.5MPa respectively at the time of internal displacement.The minimum Von Mises values of the femur and the prosthesis stem were respectively 6.3Mpa and 12.7Mpa when the value of the femur and the prosthesis stem both appeared on the outward shift of the rotation center.The maximum Von Mises value of the sacroiliac joint in the pelvis was 6.7Mpa when it was shifted outward from the rotation center.The minimum Von Mises value is 5.4MPa when the rotation center moves inward.The maximum Von Mises value of the prosthesis acetabulum was 4.1 MPa when it was shifted outward on the rotation center.The minimum Von Mises value of the prosthesis acetabulum was 1.3Mpa when it was shifted inward in the rotation center.The minimum value of Von Mises value of the prosthesis liner was 0.5Mpa when the rotation center of the anatomical position was reconstructed,and the value of Von Mises value of the liner in the other three experimental groups all increased and the value was the same,which was 0.6Mpa.ConclusionFor Crowe type ? DDH patients,when total hip replacement of the contralateral hip is health,the lower reconstruction of hip rotation center will increase liner stress,leading to greater wearing and tearing,which should be avoided.When total hip replacement of the contralateral hip lesions,the anatomic reconstruction of the rotational center of the hip joint has the minimum liner stress,which is theoretically the best position for reconstruction. |
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