People with fractures of the thighbone - or the distal femur - have better recovery when they move soon after surgery. But movement that prevents joint stiffness must be balanced with precautions to avoid overloading.
IHBI Associate Professor Devakar Epari is collaborating with engineers from the AO Research Institute (ARI) Davos in Switzerland to develop the biphasic plate, improving fracture stabilisation and promoting fast, robust healing.
Associate Professor Epari is a co-inventor of the plate, along with ARI Focus Area Leader Markus Windolf.
‘Our invention addresses the clinical dilemma of plates that are too rigid or too flexible, leading to suboptimal movement of the fractured site,’ Associate Professor Epari says.
The knee is the largest weightbearing joint in the body and is vulnerable to injury. The distal femur makes up the top part of a knee joint, with cartilage cushioning the bone and strong muscles at the front and back of the thigh providing support and enabling bending and straightening.
Fractures of the thighbone just above the knee joint—called distal femur fractures—are often the result in younger people of high-energy injuries, such as falls from significant heights or car accidents. Elderly people with distal femur fractures typically have poor bone quality.
Regardless of age, people with such fractures have the best recovery when they can move soon after treatment, such as walking. Treatment allowing early motion of the knee lessens the risk of stiffness and prevents problems resulting from extended bed rest, such as bed sores and blood clots.
Because traction, casting and bracing do not allow for early knee movement they are used less frequently than surgery.
Surgery may involve fixing a plate at the end of the fracture but does not usually include piecing small fragments of fractured bone together. The fixed plate keeps the shape and length of the bone correct while it heals. Individual fragments will fill in with new bone, called a callous.
‘We know that a certain degree of motion is advantageous and promotes the callus formation essential to fracture stabilisation,’ Associate Professor Epari says.
‘In contrast to conventional plates, the biphasic plate—due to its specific design—enables defined motion of the fractured site while avoiding overloading.’
The concept took shape in 2014 and 2015 when Dr Windolf had a research sabbatical at QUT, where he collaborated with Associate Professor Epari on fracture healing research. ‘It started with an idea: Let’s make a slot in the plate,’ Dr Windolf says. ‘This evolved to detailed discussions about how we could build a plate with enhanced features.’
The biphasic plate concept was proven using mechanical testing and preclinical experiments at ARI from 2016 to 2018. With support from the AO Development Incubator, the plate is undergoing a clinical proof of concept process ahead of possible certification for introduction in the European market.
The plate standardises a bone-healing environment, increases implant strength for full early weight bearing and prevents implant fatigue failure. It also enables standardised surgical procedures, makes it easier for surgeons to apply, reduces risks and improves patient outcomes.
Associate Professor Epari and Dr Windolf are confident of the plate’s success following engagement with—and input from— physicians. ‘At the AO Davos Courses 2018, we had feedback from 150 surgeons who were enthusiastic and saw a need.
‘Our aim is to get it CE marked within the next two years, and then getting it to users and building its reputation.’
IHBI Associate Professor Devakar Epari