Analysis of a retrieved Delta III total shoulder prosthesis

Abstract

A reversed Delta III total shoulder prosthesis was retrieved post-mortem, eight months after implantation. A significant notch was evident at the inferior pole of the scapular neck which extended beyond the inferior fixation screw. This bone loss was associated with a corresponding, erosive defect of the polyethylene cup. Histological examination revealed a chronic foreign-body reaction in the joint capsule. There were, however, no histological signs of loosening of the glenoid base plate and the stability of the prosthetic articulation was only slightly reduced by the eroded rim of the cup.

Does lateralisation of the centre of rotation in reverse shoulder arthroplasty avoid scapular notching? Clinical and radiological review of one hundred and forty cases with forty five months of follow-up

“…The latter complication is reported in around 75 % of cases [2,15,43] and up to 96 % in some series [48], and it can be observed as early as three to six months postoperatively [34,40,43]. It has been demonstrated that this notching is due to friction between the polyethylene humeral bearing and the pillar of the scapula [11], leading to the additional risk of creating a foreign body reaction due to polyethylene debris [34]. Half of the scapular notches are evolutive and are responsible for decreased function and greater risk of glenoid loosening [37].…”

“…This Grammont design yields satisfactory functional results, but numerous publications demonstrated that this improvement in elevation comes at a price [2,13,27,29,30,33,38,40,43,44,48]: loss of medial and lateral rotation [23,25], loss of shoulder contour, risk of instability and a high percentage of scapular notching. The latter complication is reported in around 75 % of cases [2,15,43] and up to 96 % in some series [48], and it can be observed as early as three to six months postoperatively [34,40,43]. It has been demonstrated that this notching is due to friction between the polyethylene humeral bearing and the pillar of the scapula [11], leading to the additional risk of creating a foreign body reaction due to polyethylene debris [34].…”

Grammont’s Idea: The Story of Paul Grammont’s Functional Surgery Concept and the Development of the Reverse Principle

“…The medialization of the COR leads to more concentric forces at the prosthesis-bone junction in the early degrees of elevation. It allows stable fixation of the glenoid baseplate, as has been confirmed in long-term clinical studies [25] or analysis of explanted prostheses [31]. The biomechanical study from Ahir et al [1] confirmed uncemented fixation is better than cemented in reverse-design prostheses.…”

The effect of component positioning on intrinsic stability of the reverse shoulder arthroplasty

“…The magnitude of the load applied to the joint was not representative of the forces acting in vivo. 3,9,21,33,39 Because the in vivo forces causing dislocation of the reverse prosthesis remain unknown 17 this force was selected to reproduce the standards implemented in previous studies, 18,26,31,38 and was chosen low enough to avoid deformation of the polyethylene cup. 1,11 Furthermore, it has been shown that there exist a linear relationship between the compressive and the dislocation force, 17 indicating that the stability ratio is independent of the compressive load in the reverse setting.…”

“…2,11,18,26,31,38 For the current study, testing of intrinsic stability for the reverse shoulder prosthesis was adapted from the method used in conventional shoulder arthroplasty ( Figure 1). 2,11,38 Glenoid and humeral components size 36 of a Delta III total reverse shoulder prosthesis (DePuy Inc, Warsaw, IN, USA) were rigidly fixed in specially designed clamps to allow for independent adjustment of both component versions.…”