Summary

Chronic problems involving shoulder pain and loss of function affect as many as 20% of adults. In Québec, the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) reports that musculoskeletal disorders make up nearly 37% of the occupational injuries compensated by the CSST[1] and account for over 40% of compensation costs. The IRSST’s internal data show that over the 2005–2007 period, the total costs generated annually by CSST-accepted shoulder injuries totalled $393,204,738 (Lebau et al., 2014). Rotator cuff (RC) tear and tendinopathy syndromes account for a large proportion (68%, in the case of tendinitis) of the days compensated for the ten most frequent injuries.

These indicators demonstrate the magnitude of the problem, but also draw attention to two other aspects of this phenomenon: first, it appears that shoulder injuries require proportionally more time for adequate function to be restored and for a sustainable return to work to become possible; and second, again proportionally speaking, workers with shoulder injuries appear to be managed more systematically by the Commission des normes, de l’équité, de la santé et de la sécurité du travail (CNESST). This too attests to the importance of quickly identifying individuals at risk of developing shoulder function problems to ensure that (1) only workers who truly need it are directed to effective, adapted rehabilitation programs, and (2) the treatment approach is optimized. This early screening requires a better understanding of the associations that may exist between various intrinsic parameters and shoulder function.

The general objective of this project was to perform correlation analyses between various diagnostic imaging, morphological, postural and pseudo-kinematic parameters and shoulder function in two groups of workers, one with RC tears and the other without, in order to establish the determinants of shoulder function.

The different analyses performed served to confirm the existence of associations between morphology and shoulder function. We were able to demonstrate that workers with full-thickness rotator cuff tears and severe fatty infiltration had slightly different pseudo-kinematics from those of asymptomatic workers in the same age group. While the results of this project are not directly applicable as yet, they clearly demonstrate the merit of continuing to analyze and explore parameters that may be associated with shoulder function in workers with rotator cuff tears.

This work made it possible, for the first time, to conduct a large-scale shoulder study using pseudo-kinematic images acquired through a low-dose EOS^® imaging system. It thus shed greater light on the associations between various intrinsic parameters and shoulder function.