Mechanical stability in a human radius fracture treated with a novel tissue-engineered bone substitute: a non-invasive, longitudinal assessment using high-resolution pQCT in combination with finite element analysis

Abstract

The clinical gold standard in orthopaedics for treating fractures with large bone defects is still the use of autologous, cancellous bone autografts. While this material provides a strong healing response, the use of autografts is often associated with additional morbidity. Therefore, there is a demand for off-the-shelf biomaterials that perform similar to autografts. Biomechanical assessment of such a biomaterial in vivo has so far been limited. Recently, the development of high-resolution peripheral quantitative computed tomography (HR-pQCT) has made it possible to measure bone structure in humans in great detail. Finite element analysis (FEA) has been used to accurately estimate bone mechanical function from three-dimensional CT images. The aim of this study was therefore to determine the feasibility of these two methods in combination, to quantify bone healing in a clinical case with a fracture at the distal radius which was treated with a new bone graft substitute. Validation was sought through a conceptional ovine model. The bones were scanned using HR-pQCT and subsequently biomechanically tested. FEA-derived stiffness was validated relative to the experimental data. The developed processing methods were then adapted and applied to in vivo follow-up data of the patient. Our analyses indicated an 18% increase of bone stiffness within 2 months. To our knowledge, this was the first time that microstructural finite element analyses have been performed on bone-implant constructs in a clinical setting. From this clinical case study, we conclude that HR-pQCT-based micro-finite element analyses show high potential to quantify bone healing in patients.

A novel in silico method to quantify primary stability of screws in trabecular bone

“…First, high‐resolution patient‐specific image data would be necessary. Current in vivo micro‐CT imaging techniques capable of resolving bone micro‐architecture are restricted to small animals and peripheral anatomical sites only (e.g., distal forearm and distal tibia) in humans . Further advances in the imaging technique are required to up‐scale the current scanning method to larger volumes of interest such as human upper and lower extremities.…”

Bioresorbability, porosity and mechanical strength of bone substitutes: What is optimal for bone regeneration?

“…1,36 Non-invasive and nondestructive quantitative imaging modalities have become a useful tools in monitoring the performance of CaPs in different locations. [11][12][13] The large variety of bone substitutes available on the market represents not only the different clinical needs and scenarios encountered, but also the diversity of the expected clinical outcomes. The surgeon has to assess the requirements of the bone defect to be grafted, think of the properties needed for repair, and ultimately choose the appropriate bone substitute and its associated surgical technique.…”

“…High-resolution peripheral QCT makes it possible to assess changes in bone and biomaterial/CaP structure and density in vivo/in situ with a relatively high (82 mm) resolution. 11 The low radiation exposure associated with this technique makes longitudinal follow-up in patients possible and will provide long-term clinical data of the incorporation, remodelling and resorption bone substitute materials over time. In addition, FEA models can be build from the QCT images to quantify changes in bone and bone graft substitute strength.…”

A survey of micro-finite element analysis for clinical assessment of bone strength: The first decade

“…Recent studies applied the technique to estimate the status of fracture healing in patients (de Jong et al, 2008;Meyer et al, 2014), whereas applications towards the use of evaluating the effects of biomaterials and fracture fixation have been reported as well (Mueller et al, 2011b). All these applications presently lack rigorous validation, but the initial results demonstrate that at least significant changes in strength can be detected.…”