Evaluation of novel implant fixation technology with a new pre-clinical testing method

Every year in the UK, more than 300,000 hip, knee, shoulder, ankle or elbow devices are implanted into patients for the treatment of orthopaedic pain, disease and trauma. Secure fixation of these implants in bone is essential for the procedure's success, yet is challenging to achieve as bone is a living tissue that adapts and changes postoperatively.

Researchers and industry strive to develop new technologies to improve fixation, with many aiming to take advantage of bone's living response by enabling it to grow into the implant. The design intent of these new technologies is always well-meaning, but to protect patients, it is necessary to pre-clinically test them, to confirm they are both safe and achieve their aim. However, there is a lack of appropriate methods for testing this.

Traditional laboratory pre-clinical testing methods do not allow for testing with living bone samples and thus cannot measure implant bone ingrowth/adaptation. Live animal testing has ethical issues, is expensive and is complicated by anatomical differences and unknown loading. Computational models require input and validation data and so require a previous laboratory/animal/clinical study. The other alternative is clinical trial, which is effectively experimenting on patients. It also often requires years/decades of waiting to determine the outcome, and thus is only suitable as the final step of new product development.

This research project aims to overcome limitations in pre-clinical testing by using a bioreactor system to enable implant fixation technologies to be tested against 'living' bone in the laboratory. The developed methods will be validated with established clinical technologies, before being applied to pre-clinically test a novel implant fixation concept.

The long-term ambition for this research is to lower the risk for patients enrolling on clinical trials, reduce the need for ineffective live animal testing, and improve orthopaedic implants through enabling fixation technology to be optimised for in vivo performance.

If the research objectives are met, we will have 1) developed and validated new pre-clinical testing methods for evaluating how implant fixation technologies interact with living bone tissue, and 2) used them to advance the technology readiness level of a new additive manufactured fixation concept.

The new pre-clinical testing methods will benefit society:

1) They will lower the risk for patients enrolling on clinical trials. Through understanding how living bone responds to a new implant, the risk of unexpected failure is reduced.

2) They will allow implant fixation technologies to be optimised for implant bony ingrowth. This will lead to stronger and more reliable implant fixation, and would benefit patients through lowering the risk that they will need a second revision procedure, and by allowing them to return to more demanding recreational/work activities sooner without risk of compromising their implant.

3) They will reduce the need for live animal testing for implant development, which is ethically questionable and is passionately opposed by members of the public.

The new pre-clinical testing method will also benefit the economy:

1) The UK has a world-leading orthopaedic industry. The new testing method will lower the cost of product development through avoiding the need for costly and ineffective animal testing, and by decreasing the risk of a failed clinical trial.

2) Through enabling implant fixation technology optimisation, the method will also help industry maintain its competitive edge by enabling companies to develop implants that outperform their competitors. This will allow UK industry to increase its share of the global orthopaedic implant market, which is estimated to be worth £35-40 billion.

3) Through developing new IP and licensing this through our project partner, we could enable industry/other centres of excellence to adopt our new methodology. It would also give our project partner a competitive edge in field of testing biomedical materials.

If the novel fixation concept passes the new pre-clinical tests, and is developed into a clinical technology, then it would also benefit patients by:

1) Lowering the risk of inadvertent intra-operative fractures during implantation. Current fixation technologies that allow bone to grow into the implant commonly need to be hammered into bone and the resulting high forces can cause fractures in extreme cases. The new fixation concept can be inserted at much lower forces, minimising this risk.

2) Enabling smaller, less invasive implants to be fixed reliably in bone thus allowing for minimally invasive procedures that avoid the need for lengthy hospital stays and rehabilitation programs.

The new fixation concept could further benefit the economy:

1) Through creating a spinout, or through a licensing agreement with an existing orthopaedic manufacturer, the technology could have impact in the orthopaedic implant market, creating jobs and leading to increased tax revenue.

2) Its adoption clinically could also benefit the UK's growing additive manufacturing industry by generating machine sales, and promoting the technology's capability.