Custom Design And Rapid Fabrication Of The Models For Cartilage Tissue Engineering Scaffolds In Knees

Background: Because of its special structure and function, the occurrence of acticular cartilage defects in the knee is the highest. Articular cartilage has limited capacity for self repair. Traditional therapies for acticular cartilage defects include joint lavage and debridement, subchondral drilling, abrasion arthroplasty, and microfracture. These procedures used to induce repair of articular cartilage take advantage of its intrinsic repair response. They could not restore a damaged cartilage and prevent the normal sequelae of degenerative joint disease, for the repair tissue typically was fibrocartilage but not hyaline. Current strategies for articular cartilage repair are tissue grafts, including transplantation of periosteum and perichondrium, chondral or osteochondral transfer and chondrocyte transplantation. These techniques have varying degrees of success in joint functional and symptomatic improvement, but they all have some limitations such as immune response, transmission of infectious diseases, age, the size the chondral defect and so on. With the rapid development of tissue engineering, engineered cartilage tissue offers a new strategy for the repair and regeneration of damaged articular cartilage. A great quantity of literatures has shown cartilage tissue engineering could produce high percentage of hyaline-like normal cartilage tissue. Practice proved, by tissue engineering technique, we could regenerate the damaged tissue, that is, our goal is to produce a repair tissue that has the same functional and mechanical properties of normal hyaline articular cartilage. Articular tissue engineering involves three elemental substances: cells, scaffolds and transplanting methods. The purpose of this study is, by using reverse engineering and rapid prototyping manufacturing, to custom design and fabricate the individualized models for cartilage tissue engineering scaffolds, which can be used for clinical treatment.Methods: Firstly, we surveyed and described statistically the morphology and topographic distribution of thickness of normal articular cartilage in knees. These anatomical data are the foundation for the clinical diagnosis of the cartilaginous disease of in the knee. Secondly, Cadaveric knees underwent multi-slice CT scanning for evaluating the imaging methods and value in morphological study on articular cartilage. And then we reconstructed the three-dimensional (3-D) models of the articular cartilage in the knee based on CTA images by using computer-aided design (CAD)software. To test the results obtained from CAD models and get the best method of reconstruction, the related parameter were compared with the physical measurement. Finally, we created defects on the articular cartilage of the femoral condyles. Basing on data resource from CTA continuous thin-layer scanning and according to the mirror imaging symmetry principle, the morphology of the articular defect was designed reversely with foundation of the normal articular massage. The individualized models for cartilage tissue engineering scaffolds were prefabricated by the three dimensional reconstruction, rapid prototyping manufacturing.Results: There are great morphological differences between different individuals and different joints. The thickness of articluar cartilage in the knee is not equal in different domains. Articular cartilage was demonstrated very well by MSCT arthrography imaging with the post-processing techniques. The shape and outline of articular cartilage are similar to the real one, there is no significant difference in measuring thickness of articular cartilage between the two methods. CAD models of articular cartilage in the knee based on MSCT arthrography images have the great concordance with cadaveric knee. The individualized physical models for cartilage tissue engineering scaffolds to reconstruct articular cartilage defects, basing on MSCT arthrography data and rapid prototyping technique fit the defect areas very well.Conclusions: Because of the great morphological differences between different individuals, different joints and different domains, it is necessary to custom design and manufacture the scaffolds individually for the articular cartilage engineering. Prefabricated individualized cartilage tissue engineering scaffolds for reconstruction of articular cartilage defect, basing on MSCT arthrography data and rapid prototyping technique is feasible. By using reverse engineering and rapid prototyping technique, articular cartilage engineering scaffolds with appropriate morphology can be fabricated which can be used in the foundation of tissue engineered cartilage.