Large trial validates dual mobility implants for hip fracture treatment

A major international clinical trial led by Queen Mary University of London and Uppsala University in Sweden has found that an emerging type of hip replacement implant dramatically reduces complications in people with a broken hip. 

The study, published in The Lancet, involved 1,600 patients across 44 hospitals in the UK and Sweden. The DUALITY trial is the largest clinical trial to compare dual mobility total hip replacements (DM-THR) with standard total hip replacements (THR). The team found that people treated with DM-THR were 70 per cent less likely to experience a dislocation post-surgery - the most common complication after hip replacement for fracture. 

A broken hip in older people is one of the most common serious injuries worldwide, affecting more than 14 million individuals each year and accounting for 1.4% of total direct healthcare expenditure in established market economies. The type of hip fracture studied in the DUALITY trial represents approximately half of all hip fractures experienced globally. 

A total hip replacement where both the ball and socket of the hip are replaced, is recommended for older, active individuals with some types of hip fracture. For most patients, the procedure improves mobility and quality of life, but dislocation post-surgery can be common and can have serious consequences for those affected. When dislocation occurs, patients often require emergency hospital admission, procedures to reset the joint, and sometimes further surgery. This can lead to longer recovery times, added distress, and increased risk of further health problems. 

Dual mobility-THR uses a small ball encased in a much larger plastic ball, and was developed specifically to reduce the risk of dislocation. In the DUALITY trial, the team aimed to establish if DM-THR reduced the risk of dislocation compared to THR. The results showed that the DM-THR implant does improve stability in the hip joint, making it less likely to dislocate after surgery. They found that within one year of surgery, just 1.3 per cent of patients receiving DM-THR experienced a dislocation, compared with 4.2 per cent of those given a standard THR. Importantly, the study found no increase in other risks such as infection or death, and overall complication rates were lower in patients receiving DM-THR. 

The researchers conclude that dual mobility implants should be considered the preferred option for suitable older patients undergoing total hip replacement after a broken hip. Crucially, DM-THR requires no new technology or training. Surgeons are already familiar with both implant types, meaning the change could be implemented immediately within existing practice. 

Professor Xavier Griffin, study author and Chair of the Centre of Bone and Joint Health at Queen Mary University of London and Honorary Consultant Orthopaedic Surgeon at Barts Health NHS Trust, said: 

"Dislocation is the most common major complication following hip replacement for a broken hip. People that experience this painful complication often require further surgery and the recovery following this is usually long, slow and painful. So, it has been an area that I, along with our surgeons around the world, have been wondering if there is any benefit to using these type of hip replacements in people with a broken hip. The fantastic news from DUALITY is that we can make a really substantial reduction in the risk. I hope that this research will make a real difference to many future patents who might avoid this catastrophic problem. 

I've tried to run similar studies before but never been able to deliver one that is big enough to give us a reliable answer to the question. Meeting the team in Uppsala and making this international collaboration a reality has been a game changer for accelerating how quickly we can discover the answers to these sorts of questions." 

Professor Nils Hailer, study author, Chair of Orthopaedics at Uppsala University and Consultant Orthopaedic Surgeon at Uppsala University Hospital, said: 

"After many years of analysing registry data and seeing both advantages and limitations of dual mobility hip replacements, I was eager to obtain solid evidence for or against the concept. Together with colleagues at Queen Mary, we succeeded in delivering a large, pragmatic, orthopaedic randomized trial involving both smaller hospitals and major referral centres across two countries. 

"The results provide robust support for the use of dual mobility constructs in hip fracture patients in need of a total hip replacement. Beyond the findings themselves, I believe this collaboration sets a new benchmark for future randomized trials in European orthopaedic research, and we will jointly continue working towards that goal." 

Researchers say that beyond improving outcomes for patients, reducing dislocations could have a significant impact on healthcare systems. Complications such as post-surgery dislocations increase hospital stays, require additional operating time, and drive unplanned readmissions. Although dual mobility implants are currently more expensive than standard implants, researchers believe the reduction in complications could offset the higher upfront cost. A full economic analysis is underway.