| Objective The three-dimensional(3D)printing trabecular titanium acetabular cup's surface has high porosity and mechanical properties which could mimic design of the natural bone.The mechanical load of the 3D printing trabecular titanium acetabular cup is in accordance with the normal physiological conduction,and the biological fixation is reliable.This research mainly includes the following research purposes: 1)to evaluate short-term clinical and radiographic effect in total hip arthroplasty(THA)using 3D printing trabecular titanium acetabular cup for patients combining osteoporosis via a retrospective study;2)to estimate the osteogenic ability of two different pore sizes for 3D printing porous titanium alloys and probe the optimal pore size in favour of bone defect repair and new bone ingrowth via the vivo study,which could provide the experimental basis of domestic porous titanium for bone defect repair,arthroplasty and osseous fusion in clinical treatment;3)to establish different finite element models of osteoporosis hip joint which implanted 3D printed porous trabecular titanium acetabular cup or ordinary acetabular cup,and to analyze the biomechanical effects of stress distribution and the initial stability using 3D finite element analysis method,which could provide biomechanical theoretical basis of using 3D printing trabecular titanium acetabular component for patients combining osteoporosis in THA.Methods For the retrospective study,109 patients(116 hips)who underwent THA using3 D printing trabecular titanium acetabular component and trabecular tantalum acetabular component in Guizhou Provincial People's Hospital from August 2015 to August 2016 were enrolled.TTi group had 55 patients(58 hips),including 24 males and 31 females,the mean age of inluding patients was 74.16±11.71 years,BMI was 24.35±2.56,Dual Energy X-ray Absorptiometry(DEXA)T value was-3.5±0.6.15(27.28 %)cases were diagnosed as primarily hip osteoarthritis,10(18.18 %)were developmental dysplasia of the hip(DDH)and30(54.54 %)were hip avascular necrosis(AVN).TTa group had 54 patients(58 hips),including 21 males and 33 females,the mean age was 68.71±10.24 years,BMI was23.15±2.16,DEXA T value was-3.1±0.3.13(24.07 %)cases were dignosed as primarily hip osteoarthritis,8(14.82 %)were DDH and 33(61.11 %)were AVN.Follow-ups were performed at 6 months,12 months,12 months after the operation and final follow-up.Operation time,blood loss and average length of hospital stay were compared between the two groups.Acetabular component stability and osseointegration were assessed through radiograph.SF-12 Heath Survey Questionnaire and Hip Harris scores system were recorded before and after operation to evaluate clinical effects of surgery.For the vivo study,the 3D printed porous Titanium was manufactured to cylinder with6mm-diameter and 6mm-height.Totally 48 New Zealand white rabbits were randomly divided into 2 groups,24 in the 640 um pore size group,24 in the 1200 um pore size group.A6mm-diameter defect was made in the left rear of the rabbit's lateral femoral condyle.The implant was entrapmented into defect area.The X-ray examination was taken at 4,8,12 weeks after surgery.The samples were observed by gross and morphological,hard tissue slices,scanning electron microscopy and Micro–CT at 4,8,12 weeks postoperatively.The regeneration of new bone and the bone defects in the two groups was observed by optical microscope.The bone growth was measured by IPP 6.0.6.The scanning electron microscopic was used for observing the growth of capillary regeneration,bone and fibrous tissue in the porous titanium-bone interface.Micro-CT analysis was served as the bone morphometric assay.Bone histomorphometry analysis were also performed in each groups.The thin layer CT scanning for a male adult and the finite element software were used for establishing 3D finite element models of osteoporosis hip joint which implanted 3D printed porous trabecular titanium acetabular cup or ordinary titanium acetabular cup.The stress value and displacement of acetabular and prosthesis were observed after the surgery of implanting 3D printed porous trabecular titanium acetabular cup or ordinary acetabular cup.In order to estimate the initial stability of the acetabular cup,we analyze the micromotion of acetabular prosthesis for the implanted 3D printed porous trabecular titanium acetabular cup and ordinary titanium acetabular cup.Results For the retrospective study,102 patients(108 hips)were followed up from 18 to23 months,with an average of 20.24 months.50 patients(52 hips)were included in the TTa cup group,52 patients were in the TTi cup group(56 hips).There was no significant difference regarding operation time,blood loss,average length of hospital stay and time to weight bearing between two groups.There was no significant difference regarding Hip Harris scores and SF-12 Heath Survey Questionnaire between two groups in 6 months,12 months,12 months after operation and final follow-up.The acetabular components were radiographically stable,with obvious bone ingrowth.No cases suffered aseptic loosening,migration,sclerotic areas,periprosthetic osteolysis and any progressive radiolucent lines.For the vivo study,the result of X-ray shows that periosteal reaction was found in the junction of porous titanium and bone at postoperative 4,8,12 weeks.No transparent bands and bone dissolution were found.Some newly regenerated bone with low density was observed in two groups.For the gross observation,we saw a few osteoid tissue in the defect area in two groups at 4 weeks postoperatively;The defect in two groups were gradually covered by osteoid tissue at 8,12 weeks postoperatively,but the Ti1200 group repair was slightly less than the Ti640 group.The hard tissue slicing observation reveals that newly regenerated bone and tissue increased in the junction of porous titanium and host bone in two groups,and new trabecular bone grew into the pores of porous titanium gradually.The combination of new bone with porous titanium became more tight,and the defects were gradually covered by new osteoid.Bone histomorphometry analysis showed that the quantity and quality of trabecular bone were superior in the Ti640 group compared to the Ti1200 group at 4,8,12 weeks after the surgery(p<0.01).The result of the scanning electron microscopic demonstrates that the calcium salt deposition,osteoblasts and new bone grew into the pores in both groups gradually increased,and the porous titanium was covered by extracellular matrix,which was better in Ti640 group compared with the Ti1200 group.The result of micro-CT analysis shows that the trabecular bone and new bone were more in the Ti640 group compared with the Ti1200 group.Bone histomorphometry analysis showed that the quantity and quality of trabecular bone were superior in the Ti640 group compared to the Ti1200 group at 4,8,12 weeks postoperatively(p<0.01).For the 3D finite element analysis,the peak stress value of acetabulum bone,metal acetabular cup and polyethylene liner of the porous titanium trabecular acetabular cup decreased significantly(53.49%,32.24%,and 28.86%),compared with ordinary titanium acetabular cup.The maximal micromotion value of the porous titanium trabecular acetabular cup was 63.5um,while the maximal micromotion value of ordinary titanium acetabular cup was 87.3um.For porous titanium trabecular acetabular cup,the area percentage of less than50 um micromotion was 85%,and of 25-50 um micromotion was 36%,of 10-25 um micromotion was 36%,and of less than 10 um micromotion was 22%.The area percentage of less than 50 um micromotion of ordinary titanium acetabular cup was 70%,of 25-50 um micromotion was 31%,of 10-25 um micromotion was 21%,and of less than 10 um micromotion was 18%.When combining osteoporosis,the initial stability of the porous titanium trabecular acetabular cup is better than ordinary titanium acetabular cup.Conclusion In THA,using 3D printing trabecular titanium acetabular cup can obtain good hip function,enhance the stability of acetabular component and achieve early bone ingrowth.It is a good choice to patients conbining osteoporosis underwent THA using 3D printing trabecular titanium acetabular cup.However,the effect of long-term follow-up still needs to be evaluated.3D printed domestic porous titanium with two different pore sizes have excellent biocompatibility.The osteogenesis and bone defect repair performance of Ti640 group is better than Ti1200 group,which could provide the biological basis of using domestic3 D printed porous titanium in clinical treatment.Porous trabecular struction of 3D printed porous titanium trabecular acetabular cup can be better to disperse and conduct the stress,decrease the stress concentration and the creep and wear of polyethylene liner,and increase the stability of the press-fit cup.The initial stability of the porous titanium trabecular acetabular cup is more excellent than ordinary titanium acetabular cup. |
PDF Full Text Request