Does posterior half-wedge augmented glenoid restore version and alignment in total shoulder arthroplasty for the B2 glenoid?

Abstract

Introduction: Walch type B2 has biconcave glenoid with posterior erosion, bone loss and humeral head subluxation. This leads to decreased glenohumeral contact area and increased contact pressure. During total shoulder arthroplasty(TSA), uncorrected retroversion causes eccentric loading and failure of glenoid component. It also leads to humeral head decentring with posterior rim loading, early glenoid wear and component loosening. This study aims to review anatomical restoration of glenoid version and humeral head centring in TSA with B2 glenoid using CT scans. Methods: This is a retrospective review of TSA for glenohumeral osteoarthritis with B2 Glenoid morphology. All polyethylene posterior wedge augmented glenoid component was used. All patients underwent pre and post surgery CT Scans. Glenoid version was calculated using neoglenoid line and medial scapular border as reference point. Post-operative humeral head centering was calculated using offset of centre of rotation of humeral head with plane of scapula on axial CT-Scan. Results: Study had 10 patients with 11 TSA between June 2017 and July 2018. Mean age was 59(45e80) years. Mean preoperative retroversion was 16(13e23)degrees. This was corrected to a mean of 0 retroversion postoperatively. 63% had good radiological correction (0e5 retroversion). Humeral head was well centered post-operatively with mean humeral scapula alignment offset of 2.1(0.8e4.5) mm posteriorly. All cases had well-centered humeral head postoperatively with offset less than 5 mm. Conclusions: Total shoulder replacement in B2 glenoid is technically demanding. Our radiological results show favourable outcome in terms of correction of gelenoid retroversion and eliminating posterior instability using wedge glenoid component. Level of evidence: IV.

Early outcomes of augmented glenoid components in anatomic total shoulder arthroplasty: a systematic review

“…The mean pre-operative glenoid retroversion reported in six studies 30,33–37 was 21.8°, with an average correction of 11.3° to 9.5° of retroversion post-operatively (Figure 5). Radiolucency around the glenoid component was noted in 37% of shoulders (four studies, 31–33,36 148 patients); however, two-thirds of these cases had a Lazarus radiolucency grading 38 of I and II (i.e., incomplete radiolucency and complete radiolucency around one peg only).…”

“…Three studies utilized a full wedge (Equinoxe; Exactech, Gainesville, FL, USA), four studies used a stepped implant (Global StepTech; DePuy Synthes, Warsaw, IN, USA), and two studies used a half wedge component (Aequalis Performþ; Wright Medical Group, Memphis, TN, USA). [29][30][31][32][33][34][35][36][37] Study characteristics of included studies are summarized in Table 1.…”

Subluxation in the Arthritic Shoulder

“…Several terms have been used to describe the relationship of the humeral head to the body of the scapula, including “subluxation” 4,12,14,17,23,24,28,33,34,49-60 and “humeral-scapular alignment.” 36,42-46,61,62 The use of the term “subluxation” to refer to 2 completely different scapular references (the glenoid and the body) has led to confusion in the understanding, evaluation, and management of the arthritic shoulder. It may be clearer to confine the use of the term “subluxation” to refer only to the position of the humeral head on the face of the glenoid, which would be consistent with the general use of the term regarding other joints 6 .…”

“…Several terms have been used to describe the relationship of the humeral head to the glenoid fossa in the axial plane, including "subluxation" 7,9,10,12, , "centering and/or decentering" 11,[38][39][40][41] , "humeral-glenoid alignment" 13,[42][43][44][45][46] , and "concentric and/or eccentric." 22,47,48 Several terms have been used to describe the relationship of the humeral head to the body of the scapula, including "subluxation" 4,12,14,17,23,24,28,33,34,[49][50][51][52][53][54][55][56][57][58][59][60] and "humeral-scapular alignment." 36,[42][43][44][45][46]61,62 The use of the term "sublux-ation" refer to 2 completely different scapular references (the glenoid and the body) has led to confusion in the understanding, evaluation, and management of the arthritic shoulder.…”

Treatment of Glenoid Wear with the Use of Augmented Glenoid Components in Total Shoulder Arthroplasty

“…Overall, they showed the highest amount of bone removal in stepped implants followed by full-wedge, with the lowest amount of bone removal in half-wedge components 41-43 . Regarding clinical data, there are several studies that have looked at short-term outcomes, complications, and failure rates of augmented anatomic glenoid components 44-49 . Wright et al 44 retrospectively compared 24 patients who received an augmented glenoid (Exactech Equinoxe full wedge) with 24 patients who received a standard all-polyethylene glenoid and reported no difference in clinical outcomes and zero failures at minimum 2-year follow-up.…”