Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - CuraBone (Predictive models and simulations in bone regeneration: a multiscale patient-specific approach)

Teaser

Bone injuries generate high costs for the European health system. Currently different types of surgery are conducted, depending on the fracture or bone deformation of the patient. Corrective surgeries are commonly used to improve the patients\' situation. Traditionally, the...

Summary

Bone injuries generate high costs for the European health system. Currently different types of surgery are conducted, depending on the fracture or bone deformation of the patient. Corrective surgeries are commonly used to improve the patients\' situation. Traditionally, the treatment relies on classical orthopaedic techniques, but nowadays it is possible to design and fabricate patient-specific implants. Also scaffolds – bone like structures replacing bone - can be printed easily with spongy structures. Thanks to the current advances in image-based technologies, the patients\' bone shape can be replicated with a 3D-model and even 3D-printed, if necessary. Using imaging techniques like CT or MRI helps to visualize the actual inner structures of a patient. Well-fitted 3D-models of implants or scaffolds can then be designed directly on the patients\' actual surface of e.g. his broken bone. Surgeons and clinical engineers develop the implant together to ensure the best outcome for the patient.
This methodology is appropriate for preoperative surgical planning. Nevertheless, it is currently not possible to predict the outcome of different treatments and their effectiveness on the bone healing process beforehand. It is not current standard to predict the patient-specific bone ingrowth into the implant, the bone healing behavior and the bone regeneration. This is not yet done in a systematic way, but it could be possible in the future predict the patients\' recovery.

CURABONE aims to bridge this gap between research and Industry. Using current and creating new computer simulation technologies will enable us to provide optimized, patient-specific treatment of bone injuries and rehabilitation therapies. We will base the processes on image analysis to achieve a predictive methodology in order to meet every patients\' needs to its best. In short, CURABONE will focus on the development of a predictive computer-based platform for the creation of patient-fitted implants.
To achieve this global aim, CURABONE comprises three main objectives. First, musculoskeletal patient-specific models are created. These use individual patient data like bone geometries, material properties and muscle attachment locations to calculate the loads acting on the bone-implant-composition. Second, a computational-based platform is developed to simulate the impact of the therapeutic treatment, optimizing the design of implants and providing personalized rehabilitation therapies. Finally, a systematic methodology is implemented to validate the developed computational models. A quantitative comparison between clinical and numerical results will be conducted resulting in accurate personalized predictive models for each patient individual situation.
CURABONE focuses on three main orthopaedic applications: knee and shoulder joints and cranio-maxillofacial surgery and additionally evaluates different bioresorbable and non-resorbable scaffold solutions.

Work performed

Human joints carry a lot of loads and help to buffer many daily of impacts during our lifetime. Therefore, the joints also suffer most damage and degeneration. Elderly patients often experience problems with degenerations of the cartilage, ligaments, meniscus or even the bones. If all these factors occur in the same patient, a total joint arthroplasty might be necessary. A methodology has been created in order to develop personalized musculoskeletal models of the joints (see Fig. 1). This process that allows an assessment of the functional outcome after implantation according to the patient satisfaction. This methodology has been successfully applied in the knee joint, and will also be applied to the mandible, with respect to cranio-maxillofacial surgery.

To achieve a successful total joint arthroplasty, implants have to be fixated to the bone. The mechanical stability of the implant is highly dependent on the interaction between the implant and bone tissue. The long-term fixation of a porous implant is mainly regulated by the relative micro-motion between prosthesis and host bone. Therefore, a method for automatically generating a finite element model of a shoulder implant has been developed. The three-dimensional model is able to predict the micro-motion for a custom reverse shoulder implant (see Fig. 2). The model is automatically meshed and material properties are assigned. This numerical platform can be easily adapted to analyze different bones and prostheses in the future. It may have important applications in the design and planning of custom implants, calculating the results accurately and guaranteeing low computational costs at the same time.

In case of large micro-motions, the fixation of porous implants need to be improved. In this project, we proposed to fill the pores with collagen gel, in which bone cells are embedded. In order to evaluate how cells interact with collagen-based gels inducing bone formation, novel microfluidic-based in-vitro cultures have been developed (see Fig. 3).

In addition, our computer-based methodology is used for the personalized design of bioresorbable implants for cranio-maxillofacial applications. During these surgeries, over- or underbite are corrected. Currently mainly non-resorbable implants made of titanium are used for these corrections. Preoperative planning is already used to supply the surgeon with patient-specific plates. To develop bioresorbable solutions for this application, different materials will be evaluated for the different cranio-maxillofacial applications. Design changes will be evaluated to account for the weaker material and the degradation and healing process. Additionally realistic biting forces acting on the jaw will be collected and implemented as input for the simulation. (Fig. 4). One of the main challenges of this type of bioreasorbable plates is to characterize the dynamics of material degradation under different conditions. Therefore, we have designed and fabricated a new bioreactor that provides the possibility to apply different fluid flow conditions and that has been conceived to evaluate material degradation over time (see Fig. 5).

Final results

The full development of CURABONE will result in important progress beyond the current state of the art, which will result in a step-forward in the development and application of patient-specific models in orthopaedics. This, in particular applies to the three main application fields, being knee and shoulder replacement and cranio-maxillofacial implants.

The outcome will result in a significant progress beyond the state of the art. We focus specifically on the following aspects:

• A patient-specific musculoskeletal model for the assessment and prediction of the patient satisfaction after total knee replacement.
• A computer-based framework to automatically generate a finite element model of a shoulder implant including the host bone, for evaluating the mechanical stability of shoulder implants.
• Development of a computer- and experimental-based platform to test the biodegradation properties of scaffolds and implants of different biomaterials.
• A computer-based framework for assessment of the functionality of patient-specific cranio-maxillofacial plates fabricated by non-degradable and degradable biomaterials.
• A computer- and experimental-based platform to test the functionality of scaffolds in terms of bone formation.

Website & more info

More info: http://curabone.unizar.es/.