Simulation is more than Software

Free Trial Version
0 0

Load-optimized implant design
Design of an optimal patient-specific implant using ANSYS topology optimization

In-silico comparison of acromion levy type ii implants for a patient-specific example

Sector: Medical technologySpecialist field: Biomechanics, Structural mechanics

Acromion Levy type II fractures following reverse shoulder arthroplasties are more prevalent in older patients. For the development of patient-specific implant solutions, topology optimizations have been performed. Subsequent simulation studies allow for the analysis of critical implant regions.



Within the framework of a research project of the University of Applied Sciences and Arts Northwestern Switzerland, in collaboration with PD Dr. Karim Eid of the Cantonal Hospital of Baden, the potential of topology optimization in biomechanics will be evaluated. A comparison of standard and optimized implant solutions for the treatment of acromion Levy type II fractures will demonstrate an initial use case.


Current standard implant solutions, such as a lateral clavicle plate, are not always satisfactory. A load-optimized design using ANSYS topology optimization allows for the development of specialized, patient-specific implants which account for different daily use cases of the patient.

Customer benefits

With the support of CADFEM, a parametric biomechanical model of the shoulder could be built as a basis for the topology optimization. This allowed for efficient planning and execution of a sensitivity analysis. The development of a patient-specific implant design could thus be carried out.

With the help of ANSYS density based topology optimization, it was possible to challenge historical standard implant designs and develop load-optimized structures based on real world daily use cases.

M.Sc. Janick Zehnder, Fachhochschule Nordwestschweiz, School of Life Sciences, Biomedical Engineering

Project Details


Optimizing performance is a well-established basis in the process of general product development. However, in the field of biomechanics, complex shapes, various superimposed loading scenarios and patient-specific differences complicate the development of suitable implant designs for the treatment of specific bone fractures. Topology optimization is a tool based on the finite element method, which allows for the automated generation of optimized structures for specific load scenarios. This tool has great potential to increase efficiency and creativity in patient-specific implant design.

In this project from the University of Applied Sciences and Arts Northwestern Switzerland, in collaboration with PD Dr. Karim Eid of the Cantonal Hospital of Baden, the acromion Levy type II fracture following reverse shoulder arthroplasties will be analyzed. The exact mechanisms leading to such a fracture are still not fully understood. In addition, there are no implants specifically developed to treat this fracture. This work aims to qualitatively explain the causes of an acromion Levy type II fracture with the help of a structural mechanical in-silico analysis, develop specific implant designs using topology optimization, and compare the performances of optimized implants with classic designs (lateral clavicle plate)

Customer Benefit

The simulation studies showed that potentially critical equivalent stresses can occur below the acromion arc, whereas critical maximum principal stresses develop on the superior-anterior border on the acromion, which may promote the onset of a Levy II fracture.

Compared to a conventional clavicle plate, the topology optimized implant designs showed better or improved performance with respect to maximum stresses and deformations. In addition, they had several other advantages: better anatomical fit, better mass exploitation, and more homogeneous stress distribution, which might lead to improved fatigue behavior.

Finite element analyses and topology optimization are powerful tools for the evaluation of complex biomechanical problems. The latter can deliver valuable insights into truly compliant and stress optimized designs of implants, without relying purely on historically justified implant designs.


A patient-specific 3D cortical bone model for a simplified shoulder complex (scapula and clavicle) based on CT data was built. Muscle force vectors for the anterior, middle and posterior deltoid muscles were extracted from the literature in order to generate the load cases for a patient-specific finite element model which describes the biomechanical behavior for abduction and flexion in the range of 15-120°. Automated parameter driven analyses were conducted using ANSYS optiSLang in order to analyze angle dependent stresses and deformations in the Levy type II region. This was extended by a sensitivity analysis based on changes in magnitude, orientation and origin of muscle forces. Based on the resulting critical load scenarios, a topology optimization of a patient-specific implant was set up. The muscle forces of the analyzed abduction and flexion angles were weighted based on their frequency of occurrence throughout a day. The performance of the resulting implant designs for preventive (pre Levy type II fracture) and curative (post Levy type II fracture) treatment was compared to standard lateral clavicle plates.

Images: © Fachhochschule Nordschweiz

Engineering Services
Dr. sc. ETH Manfred Maurer

Related products and training offers