OSSTEC is a pre-spin-out venture at Imperial College London seeking industry feedback on our orthopaedic implants which maintain bone quality in the long term. Existing orthopaedic implants provide successful treatment for knee osteoarthritis, however, they cause loss of bone quality over time, leading to more dangerous and expensive revision surgeries and high implant failure rates in young patients. OSSTEC tibial implants stimulate healthy bone growth allowing simple primary revision surgery which will provide value for all stakeholders. This could allow existing orthopaedics manufacturers to capture high growth in existing and emerging markets while offering hospitals and surgeons a safer revision treatment for patients and a 35% annual saving on lifetime costs. For patients, our implant technology could mean additional years of quality life by revising patients to a primary TKA before full revision surgery. Our implants use patent-filed additive manufacturing technology to restore a healthy mechanical environment in the proximal tibia; stimulating long term bone growth. Proven benefits of this technology include increased bone formation and osseointegration, shown in an animal model, and restoration of native load transfer, shown in a human cadaveric model. This technology could help capture the large annual growth (24%) currently seen in the cementless knee reconstruction market, worth $1.2B. Furthermore, analysis suggests an additional market of currently untreated younger patients exists, worth £0.8B and growing by 18% annually. Making revision surgery and therefore treatment of younger patients easier would enable access to this market. We aim to offer improved patient treatment via B2B sales of implants to existing orthopaedic manufacturer partners, who would then provide them with instrumentation to hospitals and surgeons. Existing implant materials provide good options for patient treatments, however OSSTEC's porous titanium structures offer unique competitive advantages; combining options for modular design, cementless fixation, initial bone fixation and crucially long term bone maintenance. Speaking to surgeons across global markets shows that many surgeons are keen to pursue bone preserving surgeries and the use of porous implants. Furthermore, there is a growing demand to treat young patients (with 25% growth in patients younger than 65 over the past 10 years) and to use cementless knee treatments, where patient volume has doubled in the past 4 years and is following trends in hip treatments. Our team includes engineers and consultant surgeons who have experience developing multiple orthopaedic implants which have treated over 200,000 patients. To date we have raised £175,000 for the research and development of these implants and we hope to gain insight from industry professionals before further development towards our aim to begin trials for regulatory approval in 2026. OSSTEC implants provide a way to stimulate bone growth after surgery to reduce revision risk. We hope this could allow orthopaedic manufactures to explore high growth markets while meaning surgeons can treat younger patients in a cost effective way and add quality years to patients' lives.
Integrating additively manufactured structures, such as porous lattices into implants has numerous potential benefits, such as custom mechanical properties, porosity for osseointegration/fluid flow as well as improved fixation features. Component anisotropic stiffness can be controlled through varying density and lattice orientation. This is useful due to the influence of load on bone remodelling. Matching implant and bone anisotropy/stiffness may help reduce problems such as stress shielding and prevent implant loosening. It is therefore beneficial to be able to design AM parts with a desired anisotropic stiffness. In this study we present a method that predicts the anisotropic stiffness of an additively manufactured lattice structure from its CAD data, and validate this model with experimental testing. The model predicts anisotropic stiffness in terms of density (ρ), fabric (
A stochastic line structure was formed in CAD by joining pseudo-random points generated using the Poisson-disk method Lines at an angle lower than 30° to the x-y plane removed to allow for AM manufacturing. Lines were converted to struts with 330 µm diameter. Second order fabric tensors were determined from CAD files of the AM specimens using the mean intercept length (MIL), the gold standard for determining a measure of the ‘average orientation’ of material within trabecular bone structures. 10 × 10 × 12 mm specimens of the CAD model were manufactured on a Renishaw AM250 powder bed fusion machine. The structure was built in 10 different orientations to enable stiffness measurement in 10 different directions (n=5 for each direction). Compression testing in a servohydraulic materials testing machine was performed according to ISO13314 with LVDTs used to measure displacement to remove compliance effects. Stress-strain curves were obtained and elastic moduli were estimated from a hysteresis loop in the load application, from 70% to 20% of the plateau stress. Specimen density and fabric data were fit to the observed stiffnesses using least squares linear regression. Experimental stiffnesses of the structure in 10 directions were compared to the model to evaluate the accuracy of model predictions.Introduction
Methods
