At present, orthopedic diseases such as bone defects and comminuted fractures are a key and difficult point in the field of orthopedics, and the use of external implants instead of host bone is an effective way to deal with large-scale bone defects. In the past, dense implants had the problem of "stress shielding" due to the high elastic modulus, that is, the stress could not be fully transferred from the implant to the bone, making it difficult for the bone cells around the implant to get enough stress stimulation and die.
In order to solve this problem, the porous structure is introduced into the implant, and the elastic modulus of the stent is reduced to the level of human bone by adjusting parameters such as the opening ratio, so as to achieve the matching of the implant with the human bone.
GB T 36984-2018 defines a method for calculating the porosity of porous metal material parts of surgical implants by industrial CT.
This article describes the combination by industrial CTZeiss Industrial CTThe volume area function realizes the calculation of the opening ratio and improves the accuracy of the measurement.
Step 1: Implant scanning.
With the advantages of industrial CT, implants can be scanned, high-quality volumetric data can be obtained, and the data can be imported into CT software data.
Step 2: Determine the volume area of the part.
Based on the grayscale threshold, a volume area of the whole part is created.
Step 3: Zoom in to reduce the volume area.
Depending on the material region, use Zoom to reduce the volume area to get the outer boundary region.
Use the close mode to adjust the number of layers to ensure that there are no closed holes inside.
Step 4: Invert the part volume area.
Use the function of merging volume regions to get the regions where the part is reversed.
Step 5: Cross the volume area.
Use the merge volume area inside the intersection function to get the intersection of the outer boundary area and the material inversion area, that is, the defect area.
Step 6: Calculate the porosity from the volume area.
Create a volumetric defect element from a volume area, selecting the correct defect area and the outer boundary area.
The porosity is calculated and displayed.
In recent years, the development and application of 3D printing technology is rapidly improving, the degree of implant personalization has become higher, and the structure has become more complex. This article provides a solution for calculating the opening ratio of porous implants by combining industrial CT with data software to help customers carry out more efficient R&D or product quality control.