Snap! The femoral neck breaks – a common fracture in older people. Their healing process is slower, and it is difficult to fixate the bone fragments close to a joint. The most common solution is therefore to replace the femoral head and the femoral neck with a hip implant.
For the procedure to be successful, the implant and the bone need to fuse together. But that is not as easy as it sounds, even though you would think that healing is optimised by nature. In 1 out of 20 patients, the implant loosens from the bone. Aneta Liszka, principal research engineer in Anna Fahlgrens lab. Photo credit Thor Balkhed This happens when the bone that the implant is fastened to breaks down for various reasons. This condition is costly for the health service to remedy, and extremely painful for the patient.
But there is no simple answer to why the bone breaks down. Previous research documented in medical literature has turned out to differ significantly from observations made in orthopaedic clinics. A research group at Linköping University is now trying to understand not only why the bone is broken down, but also what can be done to prevent this from happening so that the implant can attach. For this to be successful, several perspectives are needed.
“When you talk in medical terms about osteoblasts and osteoclasts for example, I find it really difficult to follow.Emma Björk, associate professor at Department of Physics, Chemistry and Biology. Photo credit Thor Balkhed I have to Google quite a lot. But I guess the same is true for you when I talk about different chemical bonds in the material,” says Emma Björk, materials scientist at the Department of Physics, Chemistry and Biology.
Anna Fahlgren, professor and cellular biologist at the Department of Biomedical and Clinical Sciences, adds:
“Yes, but I also think that we’re really good at talking to each other. We don’t leave a meeting assuming that we’ve understood. We draw a lot when we talk to each other.”
Together, they are aiming to develop a method where an orthopaedic implant can better attach to the bone, using materials the pores of which are only a few nanometres in size. Into this nanoporous material, the researchers can then “bake” various types of medical drugs and antibiotics to be released locally.
They have already shown that the attachment is stronger when a drug against osteoporosis, bisphosphonates, is present close to the implant-bone interface.Anna Fahlgren, professor at the Department of Biomedical and Clinical Sciences Photo credit Thor Balkhed
The idea now is to coat the implant with a nanoporous film with baked-in bisphosphonates. Thanks to a new method, also very small and dense three-dimensional surfaces, such as implant screws with closely spaced threads, can be coated.
“My speciality is that I can control the stability of these nanoporous materials so that they can be broken down at the right time to deliver drugs in a controlled manner. With this method, we can open up for future use of completely new medical drugs that would otherwise be toxic to the body,” says Emma Björk.
Both Emma Björk and Anna Fahlgren are mostly involved in basic research, but they agree that it is important that research has a purpose. Research should have a clear application and utility to motivate working on it.
But taking research from the lab to the orthopaedic clinic will be a challenge. Not only are grants for interdisciplinary research scarce, but product legislation may be a problem when it comes to a product resulting from the meeting between two disciplines.The implant screws that Emma Björk coates are only a few millimetres in size. The nanoporous films form a thin layer over the screw heads and threads. Photo credit Thor Balkhed
As it involves the release of medical drugs from an implant, it will be treated as a combination product. This means that it will have to be accepted as a product in some legislation and as a medical drug in others. According to Anna Fahlgren, this is among the most difficult things to achieve:
“In our view, if our basic research is good enough to be applied, maybe some implant company would be interested in it. Because we want this to come to use. And we know that there is a great need for this both in prosthetic care and in trauma care.”
Facts about bone: Bone tissue forms the skeleton. There are essentially two types of bone tissue – compact and porous. Tissue is broken down and formed throughout life. The cells that make this happen are called osteoblasts and osteoclasts. Osteoblasts build bone and osteoclasts break down bone. The function of these cells is usually in balance. But in the case of implants an imbalance may occur, and when more tissue is broken down than is formed there is a risk that the implant will loosen.