Développement et validation d’une méthode d’évaluation des translations glénohumérales 3D sous EOS

Abstract

Shoulder pain and dysfunction associated with rotator-cuff tears are very frequent and can be very debilitating for those affected. For example, simple activities of daily living such as washing ones hair or getting a glass from a high shelf can become very painful or even impossible. Even though there exist reliable tools to diagnose shoulder soft tissue pathologies, these do not allow explaining the importance of the symptoms associated to these pathologies. Indeed, some patients with massive rotator cuff tears maintain good shoulder function which does not interfere with their daily activities, while some others with small tears suffer from severe shoulder dysfunction. A better understanding of mechanisms involved in shoulder dysfunction would allow improving diagnosis of shoulder pathologies and treatment of patients. A few studies suggest that displacements of the center of the humeral head relative to the glenoid cavity (gleno-humeral (GH) translations) could be correlated to shoulder dysfunction in patients with rotator cuff tears. However, technical difficulties associated to the study of GH translations are in great part responsible for the small number of studies which have been interested in the subject. This thesis takes place within this context: the main objectives are to develop and validate a method for the study of GH translations and to verify the existence of a correlation between GH translations and shoulder function in a group of patients with rotator cuff tears. In order to fulfill these objectives, we developed a method for the analysis of GH translations based on the acquisition of sequences of biplanar radiographs with the EOS™ system. The first part of the work presented here consists in developing a radiograph acquisition protocol in pseudo-kinematics and at evaluating the repeatability of shoulder bony landmark location on the radiographs. The final method which was developed allows, following radiograph acquisition and digitization of repeatable landmarks, reconstructing a personalized, morphologically realistic scapula model and a simplified humerus model. These models are then registered to other positions for which radiographs have been acquired, and then used to describe GH translations between them. Validation of the method on 10 dry scapulae, 5 cadaveric shoulder specimens, and 5 patients has showed that GH translations could be evaluated in vivo with a precision of the order of 2 mm. Application of the method to 25 patients with rotator cuff tears and 5 healthy subjects did not allow establishing a clear link between GH translations and shoulder function, but did allow identifying some correlations between GH translation amplitude and shoulder function, mainly in women. Hence, this thesis will have contributed to major technical and scientific advancements. First, the work performed during this thesis allowed developing a method for morphological and functional analysis of the shoulder in 3D, with adequate precision, and in a minimally invasive manner. This method could eventually be exploited in a clinical setting or for studying scapula morphology or scapula pseudo-kinematics. The work performed during this thesis represents one more step in morphological and functional analysis of the shoulder, which will without a doubt improve our understanding of pathological shoulders, and in the longer term, improve diagnosis and treatment of patients suffering from shoulder dysfunction, and hence improve their quality of life.

Date	21 Feb 2013
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Nicola Hagemeister (Supervisor) & Wafa Skalli (Co-supervisor)