Article

Total reverse shoulder arthroplasty is becoming more and more the
standard therapeutic practice for glenohumeral arthropathy with massive lesions
of the rotator cuff. The biomechanical principle of this prosthesis is
represented by the reversion of the normal anatomy of the shoulder joint. This
non-anatomical prosthesis leads to a medialization of the rotation centre of the
glenohumeral joint and also to a distalization of the humeral head. All that
causes a deltoid tension increasing so allowing a larger abduction of the arm.
Main complications of the reverse shoulder prosthesis are due to the joint
instability, the scapular notching and the wear of the polyethylene insert.
PURPOSE: The main goal of the present work is to study the effect of the
positioning of the humeral component on the intrinsic stability of the reverse
shoulder prosthesis. In particular, through finite element method simulations,
the variation of the stability ratio of the shoulder joint has been calculated
for both vertical and horizontal dislocating loads depending on the humeral stem
version angle. Moreover, in order to estimate the wear of the polyethylene cup,
some analyses have been developed to calculate the pressures on the polyethylene
insert. RESULTS: The obtained results demonstrate the dislocation of a shoulder
prosthesis and the wear of the polyethylene insert can be prevented or limited by
conveniently varying the version angle of the humeral component.

Langue : ANGLAIS