The purpose of this study is to evaluate anatomical variations of the coracoacromial ligament (CAL) in relation to the etiology of subacromial impingement syndrome and rotator cuff tears. A knowledge and understanding of these variations will help to determine how such variations may influence the surrounding tissues and how the biomechanics of the shoulder works, as well as improving accurate diagnosis and subsequent treatment of shoulder impingement syndrome. The methodological approach involved the dissection of 220 cadaveric shoulders in the Centre for Anatomy and Human Identification (CAHID) with a mean age of 82 years (range 53 to 102 years). The CAL was classified according to its morphology and composed band number. The rotator cuff tendons were inspected for tears that were categorized into partial bursal and complete tears. Furthermore, the study inspected the CAL’s parameters and attachment sites: degenerative changes include acromial and coracoid spurs and attrition lesions at the undersurface of the acromion. Results: the multiple banded ligament was the most commonly observed type and was seen in 101 (46%) specimens. The attachment sites of the ligament varied as the size or number of bands of the ligament increased. An association was found between rotator cuff tears and shoulders which had three or more CAL bands (52%). In addition, shoulders with rotator cuff tears had wider attachments, thicker ligaments and larger subacromial insertions. Shoulders with rotator cuff tears also had a significant incidence and size of acromial spurs. The size of the spurs was correlated with the size of the CAL and attrition lesions on the undersurface of the acromion, and changes in morphology of the acromion. Attrition lesions at the subacromial insertion of the CAL were associated with tears in the rotator cuff tendons, and worsened as the size of the subacromial insertion increased. In conclusion, anatomical variations of the CAL showed a relationship with rotator cuff tears.

RERUME: Les modèles personnalisés 3D sont de plus en plus demandés pour la planification chirurgicale et les recherches en biomécanique. L’objectif principal de cette thèse cotutelle était d’améliorer la méthode de reconstruction 3D à partir des images radiographies biplanes proposée par Lagacé, Ohl et al., afin que celle-ci puisse être plus facilement utilisée en clinique et qu’elle puisse permettre d’aider à la planification chirurgicale et/ou l’évaluation post-chirurgicale. Le système de radiographie biplane EOS à faible dose d’irradiation est le résultat d’une collaboration entre la société EOS imaging, l’institut biomécanique humaine Georges Charpak d’Arts et Métiers ParisTech, le laboratoire de recherche en imagerie et orthopédie (LIO) de l’école de technologie supérieure de Montréal, Georges Charpak, Jean Dubousset et Gabriel Kalifa (Dubousset et al. 2010). Le principe du détecteur de rayon X est basé sur les travaux développés par le Prof. Charpak, qui réduit significativement la dose de rayonnement comparé à la radiographie standard (Dubousset et al. 2010) Quatorze indices cliniques utilisés plus ou moins couramment en clinique pour le diagnostic et le suivi des pathologies de l’épaule et pour la planification chirurgicale et son évaluation post-opératoire ont été calculé. La justesse est acceptable (biais <1 mm sauf la distance sous acrominale) et une reproductibilité (2 fois écart-type inférieur à 5 mm ou 5° sauf 2 paramètres) qui est similaire à ce qui est présenté dans la littérature. L’approche proposée apporte sur une amélioration de la reconstruction dans un contexte où il serait intéressant qu’elle devienne utilisable en routine clinique. Bien que les améliorations soient encore nécessaires, cette contribution apporte une pierre à l’analyse de l’articulation intacte et pathologique et est prometteuse quant à la possibilité de son implantation dans la routine clinique pour évaluer les interventions chirurgicales en pré- et post-opératoire. / Three-dimensional subject-specific models are increasingly requested for surgical planning and research in biomechanics. The main objective of this cotutelle thesis was to improve the 3D reconstruction method using biplane radiography images proposed by Lagacé, Ohl et al., in order to facilitate its application in clinic, especially to assist surgical planning and/or post-surgical evaluation. The low-dose biplane radiography EOS was used and an improvement to the reconstruction method was proposed. Fourteen clinical indices used more or less routinely in clinical diagnosis for monitoring of shoulder disorders and for surgical planning and postoperative evaluation were calculated and evaluated. The accuracy is acceptable and reproducibility is similar to what is presented in the literature. The proposed approach brings an improvement of reconstruction in a context where it would be interesting for clinical routine use. Although improvements are required, this contribution brings a stone to the analysis of intact and pathological joint and is promising as to the possibility of its presence in the clinical routine for evaluating pre- and post-operative surgery.