The objective of this study was to compare simulated range of motion (ROM) for reverse total shoulder arthroplasty (rTSA) with and without adjustment for scapulothoracic orientation in a global reference system. We hypothesized that values for simulated ROM in preoperative planning software with and without adjustment for scapulothoracic orientation would be significantly different. A statistical shape model of the entire humerus and scapula was fitted into ten shoulder CT scans randomly selected from 162 patients who underwent rTSA. Six shoulder surgeons independently planned a rTSA in each model using prototype development software with the ability to adjust for scapulothoracic orientation, the starting position of the humerus, as well as kinematic planes in a global reference system simulating previously described posture types A, B, and C. ROM with and without posture adjustment was calculated and compared in all movement planes.Aims
Methods
The indications for reverse shoulder arthroplasty
(RSA) continue to be expanded. Associated impairment of the deltoid
muscle has been considered a contraindication to its use, as function
of the RSA depends on the deltoid and impairment of the deltoid
may increase the risk of dislocation. The aim of this retrospective
study was to determine the functional outcome and risk of dislocation
following the use of an RSA in patients with impaired deltoid function.
Between 1999 and 2010, 49 patients (49 shoulders) with impairment
of the deltoid underwent RSA and were reviewed at a mean of 38 months
(12 to 142) post-operatively. There were nine post-operative complications (18%),
including two dislocations. The mean forward elevation improved
from 50° ( These results suggest that pre-operative deltoid impairment,
in certain circumstances, is not an absolute contraindication to
RSA. This form of treatment can yield reliable improvement in function
without excessive risk of post-operative dislocation. Cite this article:
