Feasibility Study Of 3D-pringting Navigation System Combined With Allogenic Fibula And Screw Fixation For Early Stage Femoral Head Necrosis

Objective:1.to study the feasibility of exact location productivity of early stage femoral head necrosis with 3D-pringting navigation module.2.to study the biomechanical influences of femoral head by drilling decompression +allogenic fibula implantation +screw fixation and simple drilling decompression.3.to study the biomechanical influences of femoral neck by drilling decompression +allogenic fibula implantation +screw fixation and simple drilling decompression.Methods:1.24 fresh pig femurs were divided into 3 groups,with 8 in each group and marked A,B and C separately,6mm diameter balls were put into each femur head to mimic head necrotic lesions.Group A: one head was picked randomly to mimic simple drilling decompression in each pig,and the rest one left untouched as control group.Group B:one head was picked randomly as simple drilling decompression,with another head as 3D-pringting navigation decompression group.Group C: one head was picked randomly as 3D-pringting navigation decompression group,with another head as untouched control group.2.CT scans were taken in 3D-pringting navigation clusters in group B and C,data were loaded into Mimics 20.0 software to design the modules for 3D printing.With the aid of C-arm radiograph,simple drilling decompressions were performed in each simple drilling decompression cluster of group B and C,with heads of Kirschner wires(3mm in diameter)being left in 2mm to cartilage layers of femoral head.Navigation clusters in groups B and C were performed drilling decompression with aids of 3D printing modules,also with Kirschner wires in femoral head.All groups with Kirschner wires placed were taken to perform CT scanning,the distances from tips of Kirschner wires to necrotic lesions in femoral heads were calculated with Mimics software.3.All simple decompression clusters in group A and B were performed simple decompressions(6 holes)only with the aids of C-arm.But navigation clusters in group B and C were performed 3D-pringting navigation system combined with allogenic fibula and screw fixation.4.4 randomly chosen femurs in group A,B and C were picked out for maximum biomechanical loading test of the femoral heads,and also maximum biomechanical loading tests of the femoral necks were taken for the rest femurs.Results:1.Distances from tips of Kirschner wires to necrotic lesions in femoral heads were 2.327±0.7061 mm,9.427 ±2.480 mm in simple decompression group,deviation distances were much less in 3D navigation group comparing to simple decompression group,with a significant statistical value(p<0.01).2.Maximum biomechanical loadings in 3D navigation group were stronger than results in simple decompression group,with a significant statistical value(p<0.01);and parameters in control group were also stronger than that in simple decompression group,with a significant statistical value(p<0.01).3.Maximum biomechanical loadings of femoral neck in 3D navigation group were less than that in simple decompression group,but the statistical comparing results had no valuable meanings with a p value equal 0.38.And maximum biomechanical loadings of femoral neck in simple decompression were the lowest in all 3 groups with a statistical p value below 0.01.Conclusions:1.Technical 3D printing navigation modules had excellent location effects in treating early stage femoral head necrosis,and this technology had feasible value in location and depth calculations.2.3D-pringting navigation system combined with allogenic fibula and screw fixation could effectively maintain the mechanical strength of femoral head and neck,comparing to simple decompression method,it extraordinarily consolidated the strength force under cartilage layer of femoral head and made an important role in protecting femoral head collapse,therefore reducing fracture risks after operation by intensifying biomechanical strengths of femoral neck.