From 5 to 10% of fractures are non-healing. A figure which risks increasing with the ageing of the population. It is thus vital to understand the causes. A mathematical model and in vivo experiments have enabled a link to be established between certain of these fractures and the absence of stem cells. Research which has been published in the journal PLoS Computational Biology.

At a crossroads between equations and microscopes, biomedical engineering is developing fully. It is in this discipline that Liesbet Geris is working, after having pursued studies in mechanical engineering. ‘I hesitated between medicine and engineering studies. The more practical, more technical aspect of applied sciences seduced me, but I was still very interested in the functioning of the human body.’ Today a lecturer at the ULg and a guest lecturer at the KUL, Liesbet Geris has from the beginning of her doctorate devoted herself to the study of bones in silico, with the aid of a numerical model simulating the mechanics of our skeletons.

In her latest article (1), co-written with Anita Reed from the University of Oxford, she looks at a certain type of non-healing fractures, atrophic fractures. ‘Within these fractures, there is no longer a trace of biological activity. There is thus no reconstruction of the bone structure. But there exist other non-healing fractures, hypertrophic ones. In these cases, there is often a mechanical instability within the fracture which cause too large movements to allow for a healing of the bone.’

Establishing the causes and envisaging treatments for these fractures is an important issue for the future. They represent between 5 and 10% of all fractures. The ageing of the population and certain associated diseases, such as osteoporosis, risk having an incidence on the number of fractures. ‘Today, there exist different methods of healing them,’ details Liesbet Geris. ‘The first consists of excising the bone up to the area where it is still healthy, or it is bleeding, and then compressing the two halves in order to recreate a positive environment for the healing. If the excised zone is too large other solutions thus have to be found. A commonly applied solution is bone transport. This operation consists of causing a second fracture where the bone is still healthy. During the first healing phase, when fibrous tissues are forming, the bone has a relative elasticity which permits the distraction, the stretching of these tissues. The distraction is carried out up until the tissues reach the first fracture. Unfortunately it is a very restrictive process. Even if the success of this operation can be aided by the injection of growth factors, the repairing of the bone takes several months. And it is not always easy for surgeons to know which treatment will be the most appropriate. It can happen that you see patients who have been subjected to a whole series of operations stretching over several years and whose fracture still has not healed.’

(1)  Liesbet Geris, Anita A.C. Reed, Jos Vander Sloten, A. Hamish R.W. Simpson, Hans Van Oosterwyck, Occurrence and treatment of bone atrophic non-unions investigated by an integrative approach