A computer project just completed at Southampton University in the UK should lead to better performing, longer-lasting joint replacements.
The project developers are now looking for partners who wish to put the model into practice.
Currently, joint replacement surgeons rely on their experience to decide how best to replace worn out joints with artificial
components. But even these artificial components break down, some after only a few years.
The MXL computer model developed at Southampton University promises to improve on that.
The idea is that with MXL, even less-experienced surgeons will be able to select and carry out a safe surgical route and achieve optimum
joint performance for each patient, whether this is surgery to preserve the joint, or complete replacement if it is worn out.
Markus Heller, project leader and Professor of Biomechanics says in a statement released this week that nearly 10% of all joint
replacement procedures carried out in the European Union every year are to replace worn out prosthetics.
“These ‘revisions’ of joint replacement surgery are complex, require a longer rehabilitation and also come at a substantial cost,
with a hip revision estimated to cost €80,000 (£69,000, or $103,000),” says Heller.
The most common reason for fitting a new joint is because of osteoarthritis, a disabling disease that affects the joints of 4 in
10 people over the age of 60.
There are different types of joint surgery, ranging from repairs that reduce the risk of the joint wearing out early, to full
joint replacement. In the EU alone, over a million joint procedures are carried out every year.
Success in this type of surgery is defined by two main outcomes: how well the repair or new joint performs after surgery, and how
long it lasts.
The MXL computer model brings together different sources of information to define the mechanics of a particular artificial joint
for a particular patient.
It uses information about the patient’s anatomy, prosthesis design, sizing and placement. The aim is to produce a prosthetic
design and surgical procedure that optimizes the lifespan and performance of the new joint.
X-ray data about the bone and muscle structure in and around the joint, allows the model to determine exactly how the new joint
should be made and where it should sit. Heller explains:
“We developed a 3D musculoskeletal model, with data on the variations in bone shape and tissue density, which has enabled advanced
biomechanical assessment of the joint reconstruction.”
The aim is not only to produce a joint that lasts longer and fits better but is also safer for the patient.
At present, surgeons rely on their experience to judge how best to carry out the joint replacement so the prosthetic not only does
the job well but also lasts as long as possible.
But much of the information they rely on is already inadequate: for instance, they rely on 2D static images instead of 3D
reconstructions. And they rely on their own experience to plan the procedure rather than key facts of the mechanical conditions of
There are other areas of surgery where computer models help surgeons make decisions. For instance, in 2012 researchers in the US
reported how they developed a computer model that helps surgeons
calculate pressure inside the brain so they have the option to monitor head injuries without having to risk invasive
But in the case of joint replacement, there are currently no computerized models that support the surgeon’s decisions with
reliable facts and data on how the joint can be expected to perform mechanically once fitted.
The computer systems created by the MXL project were funded by the European Commission’s Seventh Framework