Session: 02-02-01: Design, Modeling and Systems

Paper Number: 112550

112550 - Human Modelling and Design of Custom-Made Knee Implants: Definition of an Automatic Procedure 

Human modelling allows the representation of human body or part of it with their physical properties, characteristics and behaviours through computerized virtual models. These models can be used to design medical devices or products and their interaction with the human body. An example is the design of knee custom-made implants, that is becoming increasingly feasible in orthopaedics, particularly in total knee arthroplasty (TKA). TKA is the recommended surgical treatment for end-stages knee osteoarthritis (OA). Even if it is a widely performed surgery, up to 30% of the patients is unsatisfied by the functional outcome after the intervention, due to several causes, such as malalignment or implant fit. The usual surgical procedure implies the implant of knee prosthesis, that are available in standardized sizes. They accommodate the majority of the population and some little anatomical variation. However, it may happen that there is anatomical mismatch between the standard off-the shelf prosthesis and several morphological variations due to different genders and ethnicities. A possible solution to this is to create custom-made implants to overcome a limitation of the standard prosthesis. The aim of the present research is to define an automatic procedure to create customized knee implants by means of 3D modelling techniques. The proposed method permits to accommodate a wide range of anatomical variations, increasing the rate of patients’ satisfaction.
Three dimensional models are reconstructed through a segmentation process starting from magnetic resonance (MR) or computed tomography (CT) images. Firstly, a virtual standard prosthesis is aligned to a reference femur. Cut planes are created for cutting the femur to match the femoral implant. A set of key anatomical landmarks are defined on the femoral surface of a reference 3D model. In this way it is possible to characterize femoral structures, such as the intercondylar notch and the shape of the condyles. Then, a registration method is used to achieve rapid alignment of femoral samples. The femoral mesh is aligned and posteriorly adjusted to match the reference mesh and, accordingly, landmarks and reference planes are transferred from the reference mesh to the femoral samples. Then, the lower part of the femur is extruded with a thickness that match with the natural anatomy of the patient. Hence, the new cut planes are used to design the new femoral implant. Through this method it is possible to obtain customized prosthesis in an automatic way. Patient-specific implants present several advantages for the patients. Perfect fit and greater stability are ensured, since the prosthesis is designed and manufactured to the specific shape and size of the patient's knee. The customized implant reduces pressure on nearby joints and soft tissues, improving its longevity and comfort during use. Furthermore, the implant can be adapted to meet the patient's specific needs in terms of movement and flexibility.

Presenting Author: Anna Ghidotti University of Bergamo

Presenting Author Biography: She is a PhD student in Innovation, Technology and Management at the University of Bergamo. Her research focuses mainly on 3D modelling of human districts for morphological analysis, surgery planning or product customization. Furthermore, she deals with motion capture techniques for clinical applications. She collaborates with public and private hospital in Italy.

Authors:

Anna Ghidotti University of Bergamo
Andrea Vitali University of Bergamo
Daniele Regazzoni University of Bergamo
Caterina Rizzi University of Bergamo