More than 15% of non-conforming total shoulder arthroplasties (NC-TSA) lead to complications ; 40% of them are related to glenoid loosening characterized by loss of implant fixation in bone. This problem seems to be related to small prosthetic head translations and the stresses on the glenoid implant. Both are influenced by various factors such as prosthetic mismatch or rotator cuff tear. However, the lack of biomechanical tools adapted to the NC-TSA context makes the knowledge of implied behaviour difficult. The topic of this thesis was the development of experimental and numerical tools to quantify humeral head translations as well as contact between head and glenoid components to evaluate glenoid loosening risk during a dynamic arm elevation.
As a first step, an experimental device simulating abduction with scapulo-humeral rhythm of an entire arm is described. This device allows measuring humeral head translation during movement. It has been used to provide a proof of concept of a new glenoid implant designed to reduce the glenoid loosening risk.
As a second step, a new inverse dynamic musculoskeletal shoulder model is detailed. It was developed with the AnyBodyTM software and allows reducing the limitations of previous numerical choices. Especially, the commonly modeled three degrees of freedom (DoF) glenohumeral joint was replaced by a five DoF joint. To do so, the force dependent kinematic algorithm was used, enabling estimation of humeral head translations during abduction movement. Moreover, contact between implant was added, allowing computation of center of pressure (COP) and contact area, that was unable until now.
This numerical tool will allow answering clinical questions linked to NC-TSA. It has already been used during this PhD project and showed that an optimum mismatch would be of the order of 3.4mm since correlated to smaller humeral head translations and larger contact area. Furthermore, a subscapularis tear seems to conduct to a modification of the COP displacement during movement.
| Date | 29 Oct 2014 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Nicola Hagemeister (Supervisor), Patrice Tétreault (Co-supervisor) & Natalia Nuño (Co-supervisor) |
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Sins, L. (Author),
Hagemeister (Supervisor), Tétreault (Co-supervisor) & Nuño (Co-supervisor),
29 Oct 2014Student thesis: Doctoral thesis › Doctorate in Engineering: Engineering