Simon Mifsud, CEO of Garland Surgical asks what are the alternatives for younger patients in need of a total hip replacement
Total Hip Replacement (THR) has proved extremely effective in reducing pain and disability for many patients with hip arthritis, which affects over 600 million people around the world. However, while THR is a proven way to improve pain and function, replacement hips typically only last between 10-25 years, meaning for younger patients and those seeking a more active lifestyle post-surgery, options are limited.
The most common complication of THR is that they wear out, producing harmful particles in the hip joint, that cause an inflammatory response, potentially resulting in bone loss, pain and implant failure, and ultimately a revision procedure. Additionally, patients are at risk of post-operative dislocation, especially younger, more-active patients, meaning that many will not continue to participate in activities they enjoy.
While revision surgeries are not something anyone chooses unnecessarily, they also carry higher risks than primary THR – from additional anaesthesia risks with increased risk of co-morbidities over time, to prolonged inactivity, additional rehabilitation costs, increased time off work and medical expenses.
It is understandable therefore that, as things stand, many younger patients are advised to wait as long as possible before undergoing primary THR surgery.
However, while a short delay to surgery can make sense from the point of view of reducing the likelihood of time-generated revision surgeries, such delays are not without their own risks.
For example, decreased physical activity because of restrictive hip pain can encourage weight gain and the risk of developing associated lifestyle-related diseases such as type II diabetes, high cholesterol and cardiovascular disease. Lifestyle restrictions for younger patients can also significantly impact family life, as well as the ability to work, causing mental health problems – and that is before factoring in the additional pressures that can be caused by increasing medical costs.
So, if the mean age for THR in England and Wales is 69, what are the alternatives for younger patients?
The first option is conservative treatment and to wait as long as possible before receiving a primary THR, mitigating the likelihood of needing revision surgery. This delay is not without risk though and, even if revision surgery is not required, existing THR implants do not facilitate the range of motion many younger patients would like to maintain an active lifestyle post-surgery.
Hip resurfacing is an alternative option for some patients that can ‘buy time’ before THR. But while this can provide a good option for younger men, it is not suitable for women of childbearing age due to the danger of metal ion release into the body, which are potentially harmful to the foetus.
Surely, more than 50 years after the first successful THR, should we not have better options for younger patients?
In an ideal world, hip replacements should have the ability to function for the duration of a patient’s life – certainly for around 50 years or so – reducing the need for revision surgeries and supporting patients to maintain more active lifestyles.
One innovative new solution – the MaltaHip – is currently being developed and tested to achieve just that.
Inspired by the ankle joint, which is less prone to arthritis despite carrying more weight than the hip, the novel design consists of three unidirectional articulations that reproduce the hip joint’s natural movements, offering greater range of motion and joint stability than existing designs.
The design also tackles another known cause of THR failure – prostheses wear. Evaluations carried out in a hip joint simulator at EndoLab®, an accredited laboratory specialising in implant testing according to international standards, showed that the new design experiences at least 75% less wear than a conventional implant of a similar size, based on the number of steps a typical individual takes over a five-year period.
The MaltaHip’s implant articulations comprise of a soft component made of a special medical-grade polymer known as ultra-high-molecular-weight polyethylene, along with a hard component made of stainless steel. Since each joint moves in only one direction, not only does this type of joint minimise cross-shear (the phenomenon known to create wear debris in traditional THR devices), but also allows the long molecular chains that comprise the polymer to align along this direction over time, enhancing its strength and wear resistance. Additionally, the cylindrical shape of the joint distributes pressure more uniformly and reduces the contact stresses on the surface compared to traditional ball-and-socket THR designs, further minimising implant wear.
Results from cadaveric surgery trials are proving encouraging, with the new design demonstrating an excellent range of motion and biomechanic stability. Surgeons involved with the trial achieved extreme joint angles without dislocation; a key driver of revision surgeries and, as such, a crucial development for younger patients seeking a wider range of motion and activity following surgery.
Whilst there is still a long way to go, this collaborative effort between engineers at Garland Surgical, the University of Malta, orthopaedic surgeons at Mater Dei Hospital, Malta and the Royal Orthopaedic Hospital, Birmingham (UK) potentially offers a longer-lasting, more reliable solution for hip replacement surgeries that could bring real hope to younger patients.
The potential benefits in terms of quality of life, financial impact and opportunities to reduce waiting lists for THR surgeries around the world are significant. Isn’t it time we imagined better for younger patients?
Image: Malta Hip assembly, Garland Surgical
