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The high failure rate of metal-on-metal hip implants led to worldwide concern. Collaborative research between Newcastle University and University Hospital of North Tees identified design features that are considered to have contributed to the failure. The research helped to inform policy makers both nationally, such as the Medicines and Healthcare products Regulatory Agency (MHRA), and internationally, such as the US Food and Drug Administration (FDA). The final outcome was a worldwide withdrawal of one design of implant (the DePuy ASR) and a ban in several countries of a set of implants sharing common features (large head metal-on-metal total hip replacements). The research has reduced the risk of harm to patients who will now receive products with a significantly lower failure rate, and will have financial implications for implant manufacturers and healthcare providers.
Over 100,000 hip joint replacements are performed each year in the UK. The correct restoration of joint centre is critical to the successful outcome of total hip replacements. Failure to do so results in dislocation, increased wear and leg length discrepancy.
In collaboration with QUB, over 4,000 patient-specific custom hip prostheses were manufactured and implanted at Musgrave Park Hospital, Belfast, leading to accurate restoration of anatomical joint centre.
As a consequence a new surgical instrument has been developed and utilised in more than 4,000 surgeries. Surgical costs are reduced compared to the alternative of computer-aided surgery. The DePuy Synthes Companies are funding the development of a later version of this surgical instrument
Research into the field of metal-on-metal (MoM) arthroplasty (joint replacement) conducted at the University of Bristol in conjunction with the National Joint Registry of England and Wales (NJR) has led to a fundamental change in the practice of arthroplasty around the world and in the clinical follow up of patients. High failure rates have been identified nationally in England and Wales for MoM total hip arthroplasty and certain designs of resurfacing arthroplasty in work conducted by our department. Deleterious systemic effects of wear debris produced by these implants have also been identified by our research. The use of these devices has declined from 14% of procedures in 2008 to less than 1% in 2012. Citing our research, national bodies including NICE (2014), the MHRA (2011 & 2012), the UK Department of Health (2012), British Orthopaedic Association (2011 & 2012), NJR (2012), British Hip Society (2011 & 2012) and the US Food and Drug Administration (FDA) (2013) have issued guidance suggesting the restricted use of such devices or close surveillance of patients in whom these devices have been implanted.
UCL research into metal-on-metal (MOM) hip replacements has developed evidence affecting the 1.5 million patients with MOM hips worldwide and led, indirectly, to a change in the regulation of all medical devices by the US Food and Drug Administration and the UK Medicines and Healthcare Products Regulatory Agency (MHRA). Direct impacts include stimulation of the first global retrieval programme for medical implants, [text removed for publication], and the development of a change in the MHRA protocol used to monitor all UK MOM hip patients. These have led to improvements in the quality of patients' lives after redo surgery, and supported litigation cases worth billions of dollars against health providers — including Johnson & Johnson — to fund compensation and earlier-than-expected redo hip operations. Public awareness of issues with MOM hips has been stimulated through widespread media coverage and creation of information resources by charities and regulatory bodies.
Metal-on-metal hip resurfacing was developed in the 1990s to provide a long-term solution for young, active patients with hip disease. After observing severe adverse soft tissue reactions (pseudotumours) occurring in a growing percentage of patients with metal-on-metal resurfacing, researchers from the University of Oxford highlighted the problem and identified key patient, surgical and implant related risk factors. Clinical guidelines have been introduced to emphasise the risks, and several implants have been withdrawn from the market by the manufacturers. This research has led to a dramatic decrease in the use of metal-on-metal bearings in hip replacement.
Each year an estimated 1,324,000 artificial knee joints (total knee replacements — TKR) are implanted worldwide; an estimated third of these utilise an implant manufactured by DePuy International. Underlying computer-based research performed by the Bioengineering Sciences Research Group has played a central role during the development of a new design of TKR for DePuy. The design programme, the biggest in DePuy's history, had a budget in excess of US$10 million and aimed to replace the existing TKR system, which had annual sales of approximately US$100 million.
Between 2007-2010, DePuy adopted the computational techniques developed by the group as screening tools to (i) assess polyethylene wear and (ii) account for the effects of surgical variability during the early design phases. DePuy states "This research allowed us to choose the most robust solution when proceeding to mechanical testing and saved years in the design cycle. Patients also benefit from increased confidence in an implant that is able to withstand the rigors of use".
Research at Strathclyde University, led by Professor Helen Grant, provided data that contributed to the withdrawal of the DePuy ASRTM metal-on-metal hip resurfacing implant from the market in September 2010. This withdrawal was based on the increased rates of failure, due mainly to release of metal ions from the cobalt-chrome alloy implant into patients' blood circulation. Over 93,000 patients are affected worldwide. The impacts of the research were (i) clinical - with concerted focus on patient health, removal of implants if required, prevention of long term metallosis; (ii) procedural - a reduction in the use of metal-on-metal implants more generally in the UK and worldwide, decline in use of metal-on-metal articulations, and renewed focus on regulation of orthopaedic implants; and (iii) economic - income to patients who have successfully sued the manufacturers.
Our research has developed improved hip replacement fixation techniques, which have improved the biomechanical stability of implanted artificial joints. These techniques have been employed by orthopaedic surgeons, for example at Mid-Essex Hospitals Services Trust (MEHT), in primary and revision total hip replacement operations. As a result, the number of patients requiring revision hip surgery due to cup loosening has fallen by 50%. Additionally, these techniques have reduced the recovery time per operation by 3-5 days, which in addition to benefitting the patient have also resulted in an average saving per operation of £1,200.
This UoA has developed the largest independent simulation laboratory in the world for pre-clinical evaluation of the wear of artificial joints, which has been used to develop and commercialise novel pre-clinical simulation systems for joint replacements, in partnership with Simulation Solutions Ltd. Simulation Solutions Ltd is now the market leader of joint simulation systems outside North America.
We have also co-developed lower wearing ceramic-on-ceramic and ceramic-on-metal bearings for hip joints, and have worked with DePuy Orthopaedics Inc to define lower wearing tribological solutions for polyethylene knees. This work has benefited hundreds of thousands of patients worldwide during the REF period.
Long-term fixation integrity is a critical issue in joint replacement surgery that affects both quality of life of patients and the economy. The unique comprehensive study of long-term acetabular cement fixation carried out at the University of Portsmouth has significantly informed orthopaedic surgeons and impacted on their surgical practice. In addition, research on a commercial hydrogel implant TRUFIT has informed clinical and commercial decisions on the use of the implant for load bearing applications, which has led to the withdrawal of the implant from the global market.