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Table 1 Maximum and minimum moment arms of the middle, anterior and posterior sub-regions of the deltoid during scapular-plane abduction, coronal-plane abduction and flexion [36]

From: Prosthesis design and placement in reverse total shoulder arthroplasty

  Scapular-plane abduction Coronal-plane abduction Flexion
Muscle/muscle sub-region Max θ Min θ Max θ Min θ Max θ Min θ
Anterior deltoid Anatomical 39.3 120.0 2.1 2.5 30.2 120.0 2.0 2.5 40.0 120.0 11.6 2.5
RSA 38.6 97.5 7.4 2.5 35.8 90.0 15.6 2.5 36.0 75.0 25.9 2.5
Middle deltoid Anatomical 33.1 120.0 6.7 2.5 29.1 86.3 8.3 2.5 12.2 120.0 0.0 2.5
RSA 42.9 82.5 22.5 2.5 46.3 86.3 30.2 2.5 27.0 120.0 14.2 2.5
Posterior deltoid Anatomical −14.9 34.0 3.0 120.0 −15.9 5.0 2.0 120.0 −33.0 30.0 −16.3 120.0
RSA −12.4 2.5 5.2 120.0 14.1 120.0 1.3 2.5 −17.6 27.5 −13.1 108.8
  1. Moment arm magnitudes (mm) are given, as well as the joint angles at which they occur. Data are displayed for the natural anatomical shoulder and the shoulder after reverse total shoulder arthroplasty (RSA). A positive value indicates an elevator, whereas a negative value indicates a depressor