| Part ? Application of three dimensional computerised tomography reconstruction in anatomic parameters measurement and individual operation design of developmental dysplasia of the hipObjective: The acetabular coverage deficiency exist individual difference among DDH patients.Therefore,the correct direction and degree of the acetabular fragment is patient-specific during PAO operation.This paper introduces a feasible method using three-dimensional CT and computer image processing technology for customized surgical planning.Methods: CT data of 96 hips of 60 DDH patients(male: 15,female:45;average age of 29±8,14-49)and 56 hips of 52 normal peoples(male: 13,female:39;average age of 52±13,16-69)were reconstructed by using commercially available software Mimics and Imageware.Geometric parameters(LCEA?ACEA?AAVA?AASA?PASA)of each hip were measured in relation to the anterior pelvic plane after correcting for pelvic tilt and rotation.Deficiency types and degrees of acetabular dysplasia of DDH patients were determined by comparing with the normal hips and the improvement of the femoral head coverage was analysed again after virtual PAO.Customized surgery program targeted every DDH patients was designed and provided the reference for the actual operation.Results: We got a probabla 3D pelvic model by using the image processing software,doing precise measurement and close to the real PAO surgery.The LCEA,ACEA,AAVA,AASA,PASA of the normal hips in control group are 35.128 ± 6.337,57.052 ± 6.853,19.215 ± 5.504,61.537 ± 7.291,99.434 ± 8.372,respectively.Those angles of hips with DDH before surgery are 11.46 ± 11.19,35.79 ± 13.75,22.77 ± 6.13,43.58 ± 9.15,88.46 ± 8.24,which have been corrected to 33.81 ± 2.36,55.38 ± 2.09,20.16 ± 2.18,58.29 ± 7.60,84.71 ± 7.75 after surgeries respectively.After virtual Bernese PAO,the LCEA,ACEA,AAVA,AASA,PASA were corrected significantly(p<0.01).There was no statistics difference between LCEA,ACEA,AAVA of the hips after virtual Bernese PAO and those of normal hips(p=0.06,p=0.23,p=0.06 respectively).The AASA has been improved significintly(p=0.002)postoperative at the cost of reducing the posterior coverage represented by PASA,which are significantly smaller than those of normal hips preoperative hips of DDH patients(p<0.01).The average LFN of DDH group was bigger than normal group(p<0.01),while the NSA was less than normal group,but there was statistical significance(p>0.01).The average FNA of DDH group was bigger than normal value reported in literatures.58% of DDH patients had at least on site the HNO was less than normal value,which was larger than that 14% of normal control group(p<0.01);61% of DDH patients had at least on site the Alpha angle was bigger than normal value,which was larger than that 16% of normal control group(p<0.01).Conclusions: The geometric feature of the pelvis for DDH patients can be assessed comprehensively by using 3D-CT reconstruction and image processing technology.Based on this method,surgeons can design individualized treatment scheme and improve the effect of PAO surgery.Part ? The establishment of three dimensional finite element model and biomechanics analysis of developmental dysplasia of the hip with Bernese periacetabular osteotomyObjective: In order to address the clinical hypothesis that whether correct the acetabular fragment into the so-called radiological "normal" range is the best choice for all DDH with different severities of dysplasia from the biomechanical view ? If not,is there any correlation between the biomechanically optimal position of the acetabular fragment and the severity of dysplasia?Methods: Four finite element models with different severities of dysplasia were developed.A virtual periacetabular osteotomy was performed with the acetabular fragment rotated anterolaterally to incremental center-edge angles,and the contact area and pressure and Von Mises stress in the cartilage were calculated at different correction angles.Results: The optimal position of the acetabular fragment for patient 1,patient 2 and patient 3 was when the acetabular fragement rotated 17° laterally(with the LCEA of 36° and ACEA of 58°,both were the upper limit of the "normal" range),25° laterally following further 5° anterior rotation(with the LCEA of 31° and ACEA of 51°,both were within the "normal" range),30° laterally following further 10° anterior rotation(with the LCEA of 25° and ACEA of 40°,both were less than the "normal" range),respectively.Conclusions: The optimal corrective position of the acetabular fragment is severity dependent.we prudently proposed that the optimal correction CE angle of mild,moderate and severe DDH is slightly larger than the upper limit of the "normal" range,within the "normal" range and less than the lower limit of the "normal" range,respectively.Part ? Development of a novel customised cutting and rotating template and the evaluation in Bernese periacetabular osteotomy for the treatment of developmental dysplasia of the hipObjective: Bernese periacetabular osteotomy(PAO)has become the preferred choice as hip preserving surgery for treating developmental dysplasia of the hip(DDH).Individualized surgical schemes can be designed preoperatively by using various reverse engineering software and finite element analysis,but how to implement it in the actual PAO is still an unsolved problem.Methods: The patient-specific cutting and rotating template were predesigned firstly through computer-aided design based on three-dimensional(3D)modeling programs,then the templates were materialized by using rapid prototyping technology and were applied in the actual PAO.Finally,the clinical and radiographic effects were assessed and compared between new developed PAO and conventional PAO.Results: The customised cutting template fit well with the bone surface and served as a guide to help surgeons slide the osteotome to the very place planned preoperatively.An almost same acetabular fragment as the planned one was reproduced and no major complications appeared by performing osteotomy along the edge of the cutting template.The acetabular fragment was then corrected to the predesigned position through one-off manipulation by using customised rotating template.Compared with conventional PAO,the final position of the acetabular fragment was highly consistent with the planned position and postoperative morphological parameters were quite consistent with the preoperative planned data,the duration of operation and the number of irradiation was improved by using the new developed PAO.Conclusions: We demonstrate that our system was sufficiently feasible and accurate to realize the surgical planning in PAO and could help young and unexperienced surgeons shorten the learning curve. |
PDF Full Text Request