Innovations in hip replacement surgery: what is your implant made of?

hip resurfacing

Hip replacements are one of the most common joint replacement operations, and they help improve the quality of life of thousands of patients in the UK every year. The typical age range of a patient seeking a total hip replacement has tended to be between 60 and 80 years old; however, in recent years there has been a marked increase of younger patients requiring this type of operation. The reason for this trend is thought to be that some younger people are engaging in much more active lifestyles or are pursuing high impact recreational sports that have put increased pressure on their joints.

There are different types of artificial hip joints that can be used to treat patients, and the materials that they are made of can have a real impact on their effectiveness. In the continual strive for improvement in medical techniques and practices, different materials are tried and tested to try and find the best ‘fit’ for the required purpose.

Hip resurfacing

Mr Bridle explains that “resurfacing the hip with a metal on metal implant became very popular about 15 years ago.  Results of this technique have been generally very disappointing, and many designs have been withdrawn.  The small amount of metal debris which is produced can damage tissue and bone, leading to early failure and need for revision in some patients.”

Hip resurfacing has resurfaced again (if you’ll excuse the pun) and is pitched as one of the newer techniques that are offered today (compared with the conventional full joint replacement). It is described as being more suitable for younger patients because potentially “the surgeon only removes the diseased cartilage of the hip joint and resurfaces the joint – until now with a metal-on-metal implant. This approach is less invasive and leaves the patient with greater mobility after surgery”. This technique leaves more of the original bone in place, which is meant to make the reconstructed joint feel more natural. However, this is only available for male patients, as women’s hip joints comprise a different shape which means that this is not a suitable operation for them.

Until now, hip resurfacing was done with metal components, but as Mr Bridle alludes to, there have been reports of tiny metal particles working their way inside the body as a result of wear and tear on the new joint. This reportedly causes pain and discomfort around the joint and can have wider implications if these work their way into the bloodstream. As such, a new ceramic material is being trialled to try and get around this issue. The challenge with this approach is the lack of data for ceramic joints in support of their effectiveness. There is an absence of firm evidence that ceramic resurfacing provides any functional advantage, which leads some surgeons to believe this is a solution to a non-existent problem.  The surgical approach is not less invasive than a traditional replacement.

Clinical trials in the pipeline

Nevertheless, there is interest and momentum behind these innovations and clinical trials have been set up to test the effectiveness of ceramic joints (versus their metal counterparts). The aim of these trials is to provide the much-needed data to support or refute the effectiveness of ceramic resurfacing replacements.

According to Imperial College London, “the trial is designed to show that the ceramic implant is suitable for both men and women, as conventional methods for hip resurfacing are not suitable for women. The implant being tested is also the first to resurface patients’ hips without using metal.”