Anterior cruciate ligament (ACL) tears are serious injuries of the knee joint. Following such lesions, the return to previous quality of life as well as to previous level of activity cannot yet be guaranteed, and there may be long-term consequences such as secondary injuries and osteoarthrosis.

With her PhD studies in sports medicine completed in July 2016, Caroline Mouton aimed to improve the follow-up of ACL-injured patients by analysing an intra-hospital database of ACL-injured patients and by measuring knee laxity, which represents the elasticity or looseness of knee ligaments, to diagnose and follow ACL injuries.  

Caroline carried out her work at the Sports Medicine Research Laboratory of LIH’s Department of Population Health under the supervisor of Prof Daniel Theisen and Prof Romain Seil. The project involved a close collaboration with the Department of Orthopaedic Surgery at the Centre Hospitalier de Luxembourg (CHL) as well as the Sports Medicine Department of the Saarland University in Saarbrücken. Its chairman, Prof Tim Meyer was the third supervisor of Caroline’s thesis.

No such thing as a single ACL injury

By analysing a database of ACL-injured patients visiting the Centre Hospitalier de Luxembourg, she was able to identify 8 typical subgroups of patients according to gender, age, intensity of sports practice prior to injury and previous ACL injury. Each group displayed a different percentage of surgical treatment according to their profile, highlighting the will of medical doctors to personalise treatment. ‘The diversity of patient subtypes indicates that ACL injuries are complex. The results point to a need for an easier decision-making process on whether to operate a patient or not’ explains Caroline.

Understanding knee laxity

The main part of Caroline’s thesis focused on the multidirectional measurement of knee laxity. She developed protocols to measure the anterior movement of the knee (anterior knee laxity) and the more rarely assessed rotation of the knee (static rotational knee laxity) with specialised devices named arthrometers. The results obtained both in healthy individuals and in ACL-injured patients were analysed. ‘The experiments with healthy subjects aimed to define the “normal” knee laxity’, tells Caroline. ‘We found out that the interpretation of multidirectional knee laxity in healthy individuals may be more complex as initially thought, as the correlation between anterior and rotational laxity was poor, leading to a large variety of subject profiles.’

When measuring knee laxity in the non-injured knee of patients who had a so-called noncontact ACL injury, meaning an injury that did not result from a direct contact with a person or object, she observed an increased anterior displacement and internal rotation compared to the healthy controls. This suggests that higher physiological knee laxity may be a risk factor for ACL injury.  

Finally, when monitoring the injured knee of ACL-injured patients, Caroline found that the combination of anterior and rotational knee laxity leads to excellent diagnostic value if the right parameters were considered. The final diagnostic value was similar than the one observed in the literature for imaging (MRI).

Overall, the results of the PhD suggest to individualise knee laxity measurements in the care of knee ligament injuries in the future. The work also opens a perspective for other pathologies of the knee, for example for osteoarthritis.

A great PhD experience

Doing a PhD can be a long journey with ups and downs. Caroline tells about her experience: ‘From what I had heard around me before starting my PhD I thought that this period of life would become very tough. But I experienced it totally differently. Although it was very work-intensive and required strong perseverance, I went for it with passion and enjoyed it. The PhD also allowed me to develop my personality. I especially enjoyed going to congresses, talking to specialists, engaging in collaborations and communicating to the public at large. Getting the PhD degree is a great accomplishment, particularly because I feel that my work can serve directly in everyday clinical practice.’

‘Today Caroline is very well respected in the orthopaedic sports medicine world’, states her supervisor Prof Seil. ‘She has defended the Luxembourgish colours at some of the best congresses in the world and her knowledge and expertise in the field of knee laxity measurements is recognised internationally.’

Caroline Mouton defended her thesis on 14^th July 2016 at Saarland University, Germany. The defence committee rated her work as a significant advancement of the state-of-the-art, she therefore received the distinction magna cum laude. Until now she has published the impressive number of 13 research articles, of which 7 as a first author, and 3 book chapters. Her PhD, which included also a collaboration with the company Genourob in Laval (France), was supported by an AFR-PPP Public-Private-Partnership PhD funding of the National Research Fund Luxembourg (FNR).

A continuing passion

Caroline now works as scientific collaborator at the CHL in the Cellule d’Enseignement Médical et de Recherche. In her new position she aims to further improve the patient follow-up with an approach based on research and communication. ‘I see it as my mission to contribute to bridge the gap that still exists between research and clinical practice’, she tells heartily.

She is also engaged in the Basic Science Committee of the European Society for Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) whose office is based in Luxembourg. Recently, she has been invited to become a member of the Editorial Board of “Knee Surgery Sports Traumatology Arthroscopy”, one of the top 10 scientific journals in sports medicine and orthopaedics.