In Silico Clinical Trials in the Orthopedic Device Industry: From Fantasy to Reality?

The orthopedic device industry relies heavily on clinical evaluation to confirm the safety, performance, and clinical benefits of its implants. Limited sample size often prevents these studies from capturing the full spectrum of patient variability and real-life implant use. The device industry is accustomed to simulating benchtop tests with numerical methods and recent developments now enable virtual "in silico clinical trials" (ISCT). In this article, we describe how the advancement of computer modeling has naturally led to ISCT; outline the potential benefits of ISCT to patients, healthcare systems, manufacturers, and regulators; and identify how hurdles associated with ISCT may be overcome. In particular, we highlight a process for defining the relevant patient risks to address with ISCT, the utility of a versatile software pipeline, the necessity to ensure model credibility, and the goal of limiting regulatory uncertainty. By complementing-not replacing-traditional clinical trials with computational evidence, ISCT provides a viable technical and regulatory strategy for characterizing the full spectrum of patients, clinical conditions, and configurations that are embodied in contemporary orthopedic implant systems.

Modeling and finite element analysis of a new revision implant for the elbow.

Failed total elbow arthroplasties often are associated with significant bone loss, especially at the level of both humeral condyles. Regular implants might not be ideal for those revision cases and either custom-made implants or complex bone reconstruction procedures with grafts are needed. The goal of the current study was to develop a new revision implant, based on an existing total elbow system (GSB III). The new revision humeral component, with an anterior flange instead of condylar flanges, was designed in a computer-aided design program and virtually implanted in a modeled humerus from a cadaver and subsequently was tested in a finite element model under different loading conditions. The overall distribution of the von Mises stress, as a generalized stress intensity factor, did not differ significantly between the GSB III and the new revision component. There was a tendency that the anterior flange, compared with the condylar flanges, protected the implant-cement-bone interface in the critical region of the distal stem. The finite element analysis suggests that the revision concept for failed total elbow arthroplasties, to rely on existing anterior humerus cortex instead of reconstruction of the condylar bone, seems to have no disadvantage in terms of stress distribution on the implant.