Caractérisation tridimensionnelle de l’amplitude articulaire de l’épaule

The shoulder is the most mobile but instable joint of the human body due to bony constraint scarcity and soft tissue function unlocking several degrees of freedom (DoF). Shoulder mobility is a factor of performance in some sports. But its instability leads to musculoskeletal impairments, the rotator cuff tear being the most debilitating disorder. Evaluation of the shoulder range of motion (RoM) is a common indicator of shoulder function but it is often limited to a few monoplanar measurements where each DoF varies independently. These values used in computer simulation models lead to non-physiological movements.  The aim of this thesis was to develop tools for caracterizing tridimensional shoulder mobility. In this purpose it was mandatory to i) provide a method and its experimental approach to assess shoulder 3D (three-dimensional) RoM with DoF interactions; ii) propose a representation allowing 3D kinematical data interprestation; iii) present normalized shoulder amplitudes; iv) implement 3D RoM into computer simulation models to generate more realistic optimal sports technique; and v) predict safe 3D RoM and vi) safe rehabilitation exercises for patients after rotator cuff repair. i) Sixteen participants performed series of active arm movements with maximal amplitude with interactions between all the shoulder degrees-of-freedom. A motion analysis system combined with an upper limb kinematic model was used to estimate the 3D joint kinematics. ii) All 3D angular poses were included into a nonconvex hull representing the RoM space accounting for DOF interactions. The combination of elevation and rotation series is recommended to fully evaluate shoulder RoM. iii) A normalized 3D RoM space was defined by including 3D poses common to 50% of the participants into a hull of average volume.  iv) This average hull, defining physiologic mobility, was used in a computer simulation model to optimize the technique of a release move in gymnastics. With commonly used monoplanar constraints of shoulder mobility, only 17% of the simulations led to a physiological shoulder kinematics, while our 3D RoM constraints systematically ensures realistic shoulder kinematics without extra computational cost.  v) and vi) The 16 participants performed 3D shoulder range-of-motion and passive rehabilitation exercises. Stress in all rotator cuff tendons was predicted during each movement by means of a musculoskeletal model using simulations with different type and size of tears. Safety stress thresholds were used to discriminate safe from unsafe ranges-of-motion. Increased tear size and multiple tendons tear decreased safe range-of-motion. Mostly, glenohumeral elevations below 38°, above 65°, or performed with the arm held in internal rotation cause excessive stresses in most types and sizes of injury during abduction, scaption or flexion.  This thesis established an innovative representation of the shoulder mobility, which accounts for DoF interactions. Clinical evaluation will be more accurate with a large potential to better diagnose shoulder disorders. Computer simulations are now more realistic. Finally, we showed the importance of personalized rehabilitation in terms of 3D RoM, since passive early rehabilitation exercises could contribute to re-tear due to excessive stress.

Keyphrases: shoulder, kinematics, joint range of motion, movement optimal synthesis, musculoskeletal modeling, gymnastics, rotator cuff, rehabilitation