Abstract
Objective: The goal of the current study was to
determine whether and how much the stabilizing role of the
shoulder muscles changes as a function of humeral elevation
and the plane of elevation.
Methods: A musculoskeletal model,
comprising a personalized scapulohumeral rhythm, was used
to calculate the ratio of shear over compressive force (stability
ratio) of three rotator cuff muscles (supraspinatus, infraspinatus,
subscapularis) and three superficial shoulder muscles (middle
deltoid, clavicular part of pectoralis major, latissimus dorsi)
during abduction, flexion and reaching movements in ten healthy
adults.
Results: The range of the stability ratios was [±0.5] for
the rotator cuff muscles compared to [+5,-2] for the superficial
shoulder muscles. In the superior-inferior direction, the stability
ratios of all muscles changed with humeral elevation and for
infraspinatus, subscapularis, latissimus dorsi and deltoid also
with the plane of elevation. In the anterior-posterior direction,
the stability ratios of all muscles changed with humeral elevation,
except for the deltoid, and with the plane of elevation, except for
the supraspinatus, with interaction effects in all muscles.
Conclusion: The rotator cuff muscles provide greater compression
than shear forces during all tasks. The stabilizing function of
the superficial shoulder muscles examined in this study varies
during tasks.
Significance: The findings can be used to predict
in which movements the shoulder joint becomes more unstable
and can be applied to understand how shear and compressive
forces change in populations with abnormal shoulder motion.
determine whether and how much the stabilizing role of the
shoulder muscles changes as a function of humeral elevation
and the plane of elevation.
Methods: A musculoskeletal model,
comprising a personalized scapulohumeral rhythm, was used
to calculate the ratio of shear over compressive force (stability
ratio) of three rotator cuff muscles (supraspinatus, infraspinatus,
subscapularis) and three superficial shoulder muscles (middle
deltoid, clavicular part of pectoralis major, latissimus dorsi)
during abduction, flexion and reaching movements in ten healthy
adults.
Results: The range of the stability ratios was [±0.5] for
the rotator cuff muscles compared to [+5,-2] for the superficial
shoulder muscles. In the superior-inferior direction, the stability
ratios of all muscles changed with humeral elevation and for
infraspinatus, subscapularis, latissimus dorsi and deltoid also
with the plane of elevation. In the anterior-posterior direction,
the stability ratios of all muscles changed with humeral elevation,
except for the deltoid, and with the plane of elevation, except for
the supraspinatus, with interaction effects in all muscles.
Conclusion: The rotator cuff muscles provide greater compression
than shear forces during all tasks. The stabilizing function of
the superficial shoulder muscles examined in this study varies
during tasks.
Significance: The findings can be used to predict
in which movements the shoulder joint becomes more unstable
and can be applied to understand how shear and compressive
forces change in populations with abnormal shoulder motion.
| Original language | English |
|---|---|
| Pages (from-to) | 564-572 |
| Number of pages | 9 |
| Journal | IEEE Trans. Biomedical Engineering |
| Volume | 33 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Feb-2019 |