Aims. The aim of this study was to report the outcomes of different treatment options for glenoid loosening following reverse shoulder arthroplasty (RSA) at a minimum follow-up of two years. Patients and Methods. We retrospectively studied the records of 79 patients (19 men, 60 women; 84 shoulders) aged 70.4 years (21 to 87) treated for aseptic loosening of the glenosphere following RSA. Clinical evaluation included pre- and post-treatment active anterior elevation (AAE), external rotation, and Constant score. Results. From the original cohort, 29 shoulders (35%) were treated conservatively, 27 shoulders (32%) were revised by revision of the glenosphere, and 28 shoulders (33%) were converted to hemiarthroplasty. At last follow-up, conservative treatment and glenoid revision significantly improved AAE, total Constant score, and pain, while hemiarthroplasty did not improve range of movement or clinical scores. Multivariable analysis confirmed that conservative treatment and glenoid revision achieved similar improvements in pain (glenoid revision vs conservative, beta 0.44; p = 0.834) but that outcomes were significantly worse following hemiarthroplasty (beta -5.00; p = 0.029). Conclusion. When possible, glenoid loosening after RSA should first be treated conservatively, then by glenosphere revision if necessary, and last by salvage hemiarthroplasty. Cite this article: Bone Joint J 2019;101-B:461–469

Reverse shoulder arthroplasty (RSA) is commonly used to treat patients with rotator cuff tear arthropathy. Loosening of the glenoid component remains one of the principal modes of failure and is the main complication leading to revision. For optimal RSA implant osseointegration to occur, the micromotion between the baseplate and the bone must not exceed a threshold of 150 µm. Excess micromotion contributes to glenoid loosening. This study assessed the effects of various factors on glenoid baseplate micromotion for primary fixation of RSA. A half-fractional factorial experiment design (2k-1) was used to assess four factors: central element type (central peg or screw), central element cortical engagement according to length (13.5 or 23.5 mm), anterior-posterior (A-P) peripheral screw type (nonlocking or locking), and bone surrogate density (10 or 25 pounds per cubic foot [pcf]). This created eight unique conditions, each repeated five times for 40 total runs. Glenoid baseplates were implanted into high- or low-density Sawbones™ rigid polyurethane (PU) foam blocks and cyclically loaded at 60 degrees for 1000 cycles (500 N compressive force range) using a custom designed loading apparatus. Micromotion at the four peripheral screw positions was recorded using linear variable displacement transducers (LVDTs). Maximum micromotion was quantified as the displacement range at the implant-PU interface, averaged over the last 10 cycles of loading. Baseplates with short central elements that lacked cortical bone engagement generated 373% greater maximum micromotion at all peripheral screw positions compared to those with long central elements (p < 0.001). Central peg fixation generated 360% greater maximum micromotion than central screw fixation (p < 0.001). No significant effects were observed when varying A-P peripheral screw type or bone surrogate density. There were significant interactions between central element length and type (p < 0.001). An interaction existed between central element type and level of cortical engagement. A central screw and a long central element that engaged cortical bone reduced RSA baseplate micromotion. These findings serve to inform surgical decision-making regarding baseplate fixation elements to minimize the risk of glenoid loosening and thus, the need for revision surgery

Abstract. Shoulder replacements have evolved and current 4th generation implants allow intraoperative flexibility to perform anatomic, reverse, trauma, and revision shoulder arthroplasty. Despite high success rates with shoulder arthroplasty, complication rates high as 10–15% have been reported and progressive glenoid loosening remains a concern. Objectives. To report medium term outcomes following 4th generation VAIOS® shoulder replacement. Methods. We retrospectively analysed prospectively collected data following VAIOS® shoulder arthroplasty performed by the senior author between 2014–2020. This included anatomical (TSR), reverse(rTSR), revision and trauma shoulder replacements. The primary outcome was implant survival (Kaplan-Meier analysis). Secondary outcomes were Oxford Shoulder Scores (OSS), radiological outcomes and complications. Results. 172 patients met our inclusion criteria with 114 rTSR, 38 anatomical TSR, and 20 hemiarthroplasty. Reverse TSR- 55 primary, 31 revision, 28 for trauma. Primary rTSR- 0 revisions, average 3.35-year follow-up. Revision rTSR-1 revision (4.17%), average 3.52-year follow-up. Trauma rTSR- 1 revision (3.57%), average 4.56-year follow-up OSS: Average OSS improved from 15.39 to 33.8 (Primary rTSR) and from 15.11 to 29.1 (Revision rTSR). Trauma rTSR-Average post-operative OSS was 31.4 Anatomical TSR38 patients underwent primary anatomical TSR, 8 were revisions following hemiarthroplasty. In 16/38 patients, glenoid bone loss was addressed by bone grafting before implantation of the metal back glenoid component. Mean age at time of surgery was 68.3 years (53 – 81 years). Mean follow-up was 34 months (12 – 62 months). The average Oxford shoulder score improved from 14 (7–30) to 30 (9–48). There were 3 revisions (7.8%); two following subscapularis failure requiring revision conversion to reverse shoulder replacement and one for glenoid graft failure. Conclusions. The medium-term results of the VAIOS® system suggest much lower revision rates across multiple configurations of the system than previously reported, as well as a low incidence of scapular notching. This system allows conversion to rTSR during primary and revision surgery

Introduction and Objective. In recent years, along with the extending longevity of patients and the increase in their functional demands, the number of annually performed RSA and the incidence of complications are also increasing. When a complication occurs, the patient often needs multiple surgeries to restore the function of the upper limb. Revision implants are directly responsible for the critical reduction of the bone stock, especially in the shoulder. The purpose of this paper is to report the use of allograft bone to restore the bone stock of the glenoid in the treatment of an aseptic glenoid component loosening after a reverse shoulder arthroplasty (RSA). Materials and Methods. An 86-years-old man came to our attention for aseptic glenoid component loosening after RSA. Plain radiographs showed a complete dislocation of the glenoid component with 2 broken screws in the neck of glenoid. CT scans confirmed the severe reduction of the glenoid bone stock and critical bone resorption and were used for the preoperative planning. To our opinion, given the critical bone defect, the only viable option was revision surgery with restoration of bone stock. We planned to use a bone graft harvested from distal bone bank femur as component augmentation. During the revision procedure the baseplate with a long central peg was implanted “on table” on the allograft and an appropriate osteotomy was made to customize the allograft on the glenoid defect according to the CT-based preoperative planning. The Bio-component was implanted with stable screws fixation on residual scapula. We decided not to replace the humeral component since it was stable and showed no signs of mobilization. Results. The new bio-implant was stable, and the patient gained a complete functional recovery of the shoulder. The scheduled radiological assessments up to 12 months showed no signs of bone resorption or mobilization of the glenoid component. Conclusions. The use of bone allograft in revision surgery after a RSA is a versatile and effective technique to treat severe glenoid bone loss and to improve the global stability of the implant. Furthermore, it represents a viable alternative to autologous graft since it requires shorter operative times and reduces graft site complications. There are very few data available regarding the use of allografts and, although the first studies are encouraging, further investigation is needed to determine the biological capabilities of the transplant and its validity in complex revisions after RSA

Introduction. Aseptic glenoid loosening is a common failure mode of reverse shoulder arthroplasty (rTSA). Achieving initial glenoid fixation can be a challenge for the orthopedic surgeon since rTSA is commonly used in elderly osteoporotic patients and is increasingly used in scapula with significant boney defects. Multiple rTSA baseplate designs are available in the marketplace, these prostheses offer between 2 and 6 screw options, with each screw hole accepting a locking and/or compression screw of varying lengths (between 15 to 50mm). Despite these multiple implant offerings, little guidance exists regarding the minimal screw length and/or minimum screw number necessary to achieve fixation. To this end, this study analyzes the effect of multiple screw lengths and multiple screw numbers on rTSA initial glenoid fixation when tested in a low density (15pcf) polyurethane bone substitute model. Methods. This rTSA glenoid loosening test was conducted according to ASTM F 2028–17; we quantified glenoid fixation of a 38mm reverse shoulder (Equinoxe, Exactech, Inc) in a 15 pcf low density polyurethane block (Pacific Research, Inc) before and after cyclic testing of 750N for 10k cycles. To evaluate the effect of both screw fixation and screw number, glenoid baseplates were constructed using 2 and 4, 4.5×18mm diameter poly-axial locking compression screws (both n = 5) and 2 and 4, 4.5×46mm diameter poly-axial locking compression screws (both n = 5). A two-tailed unpaired student's t-test (p < 0.05) compared prosthesis displacements to evaluate each screw length (18 vs 46mm) and each screw number (2 vs 4). Results. All glenoid baseplates remained well-fixed after cyclic loading in the low density bone substitute block, regardless of screw length or screw number. As described in Table 1, the average pre- and post-cyclic displacement for baseplates with 18mm long screws was significantly greater than that of baseplates with 46mm long screws in both the A/P and S/I directions, with exception of displacements for 4 screws S/I-pre cyclic and 2 screws A/P-post cyclic loading. As described in Table 2, the average pre- and post-cyclic displacement for all baseplates with 2 screws was significantly greater than that of all baseplates with 4 screws, regardless of screw length in the A/P and S/I directions. Discussion and Conclusions. These results of this study demonstrate that rTSA glenoid baseplate fixation is impacted by both the number of screws and by the length of screws, with longer screws and more screws associated with significantly better initial fixation. However, it should be noted that none of the tested devices catastrophically failed in this non-defect/low-density model, demonstrating that adequate fixation can be achieved with as little as 2×18mm screws for some baseplate types. Care should be made when extrapolating these results to that of other designs. This study is limited by its use of only one implant design and by its use of a polyurethane substrate without any defect; future work should evaluate the effect of screw length and screw number in with multiple different prostheses in different densities of bone with and without defects

Glenoid baseplate positioning for reverse total shoulder replacements (rTSR) is key for stability and longevity. 3D planning and image-derived instrumentation (IDI) are techniques for improving implant placement accuracy. This is a single-blinded randomised controlled trial comparing 3D planning with IDI jigs versus 3D planning with conventional instrumentation. Eligible patients were enrolled and had 3D pre-operative planning. They were randomised to either IDI or conventional instrumentation; then underwent their rTSR. 6 weeks post operatively, a CT scan was performed and blinded assessors measured the accuracy of glenoid baseplate position relative to the pre-operative plan. 47 patients were included: 24 with IDI and 23 with conventional instrumentation. The IDI group were more likely to have a guidewire placement within 2mm of the preoperative plan in the superior/inferior plane when compared to the conventional group (p=0.01). The IDI group had a smaller degree of error when the native glenoid retroversion was >10° (p=0.047) when compared to the conventional group. All other parameters (inclination, anterior/posterior plane, glenoids with retroversion <10°) showed no significant difference between the two groups. Both IDI and conventional methods for rTSA placement are very accurate. However, IDI is more accurate for complex glenoid morphology and placement in the superior-inferior plane. Clinically, these two parameters are important and may prevent long term complications of scapular notching or glenoid baseplate loosening. Image-derived instrumentation (IDI) is significantly more accurate in glenoid component placement in the superior/inferior plane compared to conventional instrumentation when using 3D pre-operative planning. Additionally, in complex glenoid morphologies where the native retroversion is >10°, IDI has improved accuracy in glenoid placement compared to conventional instrumentation. IDI is an accurate method for glenoid guidewire and component placement in rTSA

Purpose:. Glenoid loosening persists as a common cause of anatomic total shoulder arthroplasty (TSA) failure. Considering radiographic evidence of loosening as an endpoint, TSA has a reported survivorship of only 51.5% at 10 years. Component loosening may be related to cementation and it is postulated that poor cement penetration and heat-induced necrosis may partially be responsible. There is a growing interest among surgeons to minimize or abandon cement fixation and rely on biologic fixation to the polyethylene for long-term fixation. De Wilde et al. reported promising early clinical and radiographic results using a pegged, all-polyethylene ingrowth glenoid design implanted without cement. The goal of this study was to compare glenoid micromotion in an all-polyethylene, centrally fluted pegged glenoid using 3 cement fixation techniques. Materials and Methods:. Glenoid components (Anchor Peg Glenoid, Depuy Orthopaedics, Warsaw, IN, USA) (Figure 1) were implanted in polyurethane foam testing blocks with 3 different fixation methods (n = 5 per group). Group I glenoids were implanted with interference fit fixation with no added cement. Group II was implanted with a hybrid fixation, where only the peripheral pegs were cemented. Group III glenoids were fully cemented for implantation. Glenoid loosening was characterized according to ASTM Standard F-2028. The glenoid component and a 44 mm humeral head were mounted to a materials testing frame (858 Mini Bionix II, MTS Crop., Eden Prairie, MN, USA) with a 750N applied joint compressive force (Figure 1). A humeral head subluxation displacement of ± 0.5 mm was experimentally calculated as a value that simulates glenoid rim loading that may occur at higher load activities. For characterization of glenoid loosening, the humeral head was cycled 50,000 times along the superior-inferior glenoid axis, simulating approximately 5 years of device service. Glenoid distraction, compression, and superior-inferior glenoid migration were recorded with two differential variable reluctance transducers fixed to the glenoid prosthesis. Results:. All glenoid components completed the 50,000 cycles of humeral head translation successfully. With respect to glenoid distraction (Figure 2), interference fit fixation had significantly greater distraction compared to both hybrid and fully cemented fixation (p < 0.001). Hybrid fixation also displayed significantly higher distraction compared to fully cemented fixation (p < 0.001). In terms of glenoid compression (Figure 2), hybrid cementation had significantly greater compression compared to both interference-fit and fully cemented fixation (p < 0.001). Discussion:. This is the first biomechanics study comparing glenoid micromotion of a centrally fluted, pegged component using 3 different fixation techniques. Of all fixation methods, the fully cemented components displayed the least amount of motion in all parameters. Hybrid fixation exhibited lower distraction, higher compression, and comparable translation compared to interference-fit fixation. Results may indicate the differences in early motion and suggest little to no advantage of peripheral peg cementation over no cement with respect to initial fixation. Future studies are warranted to further evaluate interference-fit fixation as a viable option for implantation of a central fluted, all-polyethylene glenoid component

Over the long term, the results of the insertion of a Grammont inverted shoulder prothesis are unknown. The present study reports survivorship curves and the role of the initial aetiology in patients re-examined after 5 to 10 years. Patients and methods Eighty prostheses (for 77 patients) were implanted between 1992 and 1998: 66 cases of massive cuff tear arthropathy (MCTA) and 24 cases for another aetiology (mainly rheumatoid arthritis and revision). At the time of follow-up, 18 patients had died and 2 could not be traced. The remaining patients (57 representing 60 prostheses) were seen by an independent examiner. The minimum follow-up was 5 years. The average follow-up was 69,6 months. Kaplan-Meir survivorship curves for the 60 prostheses were established in order to show the probability of failure as defined by: revision of the prothesis, glenoid loosening, and a functional level< 30 points according to the Constant score. Results The survivorship curves were as follow:. - for non revision of the prosthesis at 10 years: 91% overall; after 9 years: 95% for MCTA, and 77 % for the others aetiologies. This difference was statistically significant (p< 0,01) ; 6 implants were revised: 3 for MCTA and 3 for other aetiologies. - for non glenoid loosening at 10 years: 84 % overall ; after 7 years: 91% for MCTA and 77% for other aetiologies. This difference was statistically significant (p< 0,05). In addition to the cases of replaced implants mentioned above there was a case of glenoid loosening after 8 years follow-up in a patient aged 92. -for Constant score < 30 at 10 years: 58 % overall. The punctual survivorship rate was significantly different in function of the aetiology, at 6 years ; but this was no longer the case after 7 years. Discussion. According to revision of the prosthesis, there is a clear rupture in the survivorship curve about 3 years after insertion in aetiologies other than MCTA. This suggests that Grammont inverted total shoulder arthroplasty is not appropriate in these aetiologies (particularly in cases of rheumatoid arthritis). According to Constant score < 30, there is a clear rupture in the survivorship curve about 7 years after insertion specially in MCTA cases. This suggests that inverted protheses should be used only in cases with severe handicap and only in patients aged over 75

Introduction. Achieving prosthesis fixation in patients with glenoid defects can be challenging, particularly when the bony defects are large. To that end, this study quantifies the impact of 2 different sizes of large anterior glenoid defects on reverse shoulder glenoid fixation in a composite scapula model using the recently approved ASTM F 2028–14 reverse shoulder glenoid loosening test method. Methods. This rTSA glenoid loosening test was conducted according to ASTM F 2028–14; we quantified glenoid fixation of a 38mm reverse shoulder (Equinoxe, Exactech, Inc) in composite/dual density scapulae (Pacific Research, Inc) before and after cyclic testing of 750N for 10k cycles. Anterior defects of 8.5mm (31% of glenoid width and 21% of glenoid height; n=7) and 12.5mm (46% of glenoid width and 30% of glenoid height; n=7) were milled into the composite scapula along the S/I glenoid axis with the aid of a custom jig. The baseplate fixation in scapula with anterior glenoid defects was compared to that of scapula without an anterior glenoid defect (n = 7). For the non-defect scapula, initial fixation of the glenoid baseplates were achieved using 4, 4.5×30mm diameter poly-axial locking compression screws. To simulate a worst case condition in each anterior defect scapulae, no 4.5×30mm compression screw were used anteriorly, instead fixation was achieved with only 3 screws (one superior, one inferior, and one posterior). A one-tailed unpaired student's t-test (p < 0.05) compared prosthesis displacements relative to each scapula (anterior defect vs no-anterior defect). Results. All glenoid baseplates remained well-fixed after cyclic loading in composite scapula without a defect and those with an 8.5mm anterior glenoid defect. However, only 6 of the 7 glenoid baseplates remained well-fixed after cyclic loading in scapula with a 12.5mm anterior glenoid defect, where 1 device failed catastrophically at 5000 cycles by loosening from the substrate. As described in Table 1, the average pre- and post-cyclic glenoid baseplate displacement in scapula with 8.5mm and 12.5mm anterior glenoid defects was significantly greater than that of baseplates in scapula without an anterior glenoid defect in both the A/P and S/I directions. Similarly, the average pre- and post-cyclic glenoid baseplate displacement in scapula with 12.5mm anterior glenoid defects was significantly greater than that of baseplates in scapula with 8.5mm anterior glenoid defects in the both the A/P and S/I directions. Discussion and Conclusions. These results demonstrate that reverse shoulder glenoid baseplate fixation was achievable in scapula with an 8.5mm anterior glenoid defect. Given that one sample catastrophically loosened in the 12.5mm anterior defect model, supplemental bone grafting may be required to achieve fixation in 12.5mm anterior glenoid defects with reverse shoulder arthroplasty. Future work should evaluate whether adding additional screws mitigates the increased displacement observed in this anterior glenoid defect scenario. This study is limited by its use of polyurethane dual-density composite scapula

Introduction. Glenoid loosening, still a main complication in shoulder arthroplasty, could be related to glenohumeral orientation and conformity, cementing techniques, fixation design and periprosthetic bone quality [1,2]. While past numerical analyses were conducted to understand the relative role of these factors, so far none used realistic representations of bone microstructure, which has an impact on structural bone properties [3]. This study aims at using refined microFE models including accurate cortical bone geometry and internal porosity, to evaluate the effects of fixation design, glenohumeral conformity, and bone quality on internal bone tissue and cement stresses under physiological and pathological loads. Methods. Four cadaveric scapulae were scanned at 82µm resolution with a high resolution peripheral quantitative computer tomography (XtremeCT Scanco). Images were processed and virtually implantated with two anatomical glenoid replacements (UHMWPE Keeled and Pegged designs, Exactech). These images were converted to microFE models consisting of nearly 43 million elements, with detailed geometries of compact and trabecular bone, implant, and a thin layer of penetrating cement through the porous bone. Bone tissue, implant and cement layer were assigned material properties based on literature. These models were loaded with a central load at the glenohumeral surface, with the opposite bone surface fully constrained. Effects of glenohumeral conformity were simulated with increases of the applied load area from 5mm-radius to a fully conformed case with the entire glenoid surface loaded. The models were additionally subjected to a superiorly shifted load mimicking torn rotator cuff conditions. These models were solved and compared for internal stresses within the structures (Figure 1) with a parallel solver (parFE, ETH Zurich) on a computation cluster, and peak stresses in each region compared by design and related to apparent bone density. Results. Peak cement stresses were generally located at the interface with bone rather than implant (p<0.05), and peak bone stresses occurred around the cemented region. A larger trabecular load share was predicted with the Pegged compared to the Keeled design (Figure 2a). Superior load shift reduced this ratio but resulted in slight stress increase in the cement and implant, with the Keeled design less sensitive to this shift (Figure 2b). These effects were more pronounced with decreased overall bone density (Figure 2c). Increasing conformity significantly affected peak stresses in the cement and implant for both Keeled and Pegged designs (Figure 3) (p<0.041), but only significantly changed bone stresses for the Keeled design (p<0.047). Generally higher peak cement and trabecular bone stresses were predicted for the Pegged design. Discussion. Our detailed microFE analyses suggest that implant fixation design affects the sensitivity of internal stresses to glenohumeral load shifts, in particular within the cement region and through alterations in load sharing in the periprosthetic bone. Future steps including reverse replacements and more physiological loading conditions, combined with experimental validation tests in dynamic loading, will provide improved insights into the clinical incidences of glenoid loosening

In an effort to address the relatively high rate of glenoid component lucent lines, loosening and failure, tantalum/trabecular metal glenoid implant fixation has evolved as it has in hip and knee arthroplasty. Trabecular metal-anchored glenoid implants used in a consecutive patient case series have demonstrated a lower failure rate than traditional all polyethylene cemented glenoids. Although the radiographs of some patients demonstrated small focal areas of lucency, none have become loose, and only two have actually demonstrated glenoid component failure due to a fracture 6 years after the index procedure. One with glenoid loosening was due to polyethylene wear from a massive cuff tear occurring 8 years after the index procedure. Most patients experienced significant improvements in shoulder range of motion and reduction in pain. Trabecular metal-anchored glenoids when carefully implanted do not produce excessive failure rates, but rather result in functional improvements while decreasing operative time

There is a large and growing population of patients with shoulder arthritis that are over 70 years old. Many of these patients live alone and sling immobilization after shoulder arthroplasty is problematic. Other than improved internal rotation, there are limited benefits of anatomic shoulder arthroplasty compared to reverse arthroplasty. Anatomic arthroplasty is associated with longer OR time, longer recovery with need for assistance to allow the subscapularis to heal, and more challenging glenoid exposure. The reverse arthroplasty is a faster operation without the need for subscapularis healing and the sphere provides a more forgiving implant position. Additional benefits of reverse arthroplasty include better ability to manage glenoid bone loss and joint subluxation. Data from the Australian Orthopaedic Association National Joint Replacement Registry shows that within the first year of surgery the rate of revision of anatomic shoulder arthroplasty is less than reverse arthroplasty. However, after one year, the overall revision rate of reverse arthroplasty is less than anatomic shoulder arthroplasty. Therefore, increased technical difficulty of anatomic shoulder arthroplasty together with concerns of subscapularis insufficiency, glenoid loosening, and lack of strong evidence of superiority do not warrant changing from reverse for patients over 70 years old

Aims

The aim of this study was to report long-term clinical outcomes of a modern convertible metal-backed glenoid (MBG) in total shoulder arthroplasty (TSA).

Glenoid failure remains the most common mode of total shoulder arthroplasty failures. Porous tantalum metal (Trabecular Metal™, Zimmer) have grown in popularity in hip and knee arthroplasty. First-generation porous tantalum metal-backed glenoid components demonstrated metal debris, resulted in failure, and were revised to second-generation glenoid implants. Evidence for second-generation porous tantalum metal implants in shoulder arthroplasty is sparse.1–4 The purpose of this study was to assess clinical and radiographic outcomes in a series of patients with second-generation porous tantalum glenoid components at a minimum two-years postoperative. We retrospectively reviewed the clinical and radiographic outcomes of patients who received a second-generation porous tantalum glenoid component anatomic shoulder arthroplasty between May 2009 and December 2017 with minimum 24 months follow-up. The shoulder arthroplasties were performed by one of two senior fellowship-trained surgeons. We collected postoperative clinical outcome indicators: EQ5D visual analog scale (VAS), Western Ontario Osteoarthritis of the Shoulder (WOOS) Index, American Shoulder and Elbow Surgeons (ASES) Score, and Constant Score (CS). Radiographic review was performed by an independent fellowship-trained surgeon. The Endrizzi metal debris grading system1 was utilized to grade metal debris. We computed descriptive statistics and compared outcome scores between groups via the non-parametric Wilcoxon rank-sum test, with group-wise comparisons defined by: metal debris and humeral head migration (secondary analyses). Thirty-five patients [23 male (65.7%) and 12 female (34.3%)] with 40 shoulder replacements participated in the study. Forty of 61 shoulders (65.6%) had an average of 64 ± 20.3 months follow-up (range 31 to 95). Average BMI was 27.5 ± 4.4 kg/m2 (range 19.5 to 39.1). The average postoperative EQ5D VAS at final follow-up was 74.6 ± 22.5, WOOS Index 87.9 ± 16.6, ASES Score 88.3 ± 10.9, and CS 80.4 ± 13. At final follow-up, 18 of 40 shoulders (45%) had metal debris [15 of 40 (37.5%) Endrizzi grade 1 and three of 40 (7.5%) Endrizzi grade 2], and 22 of 40 shoulders (55%) did not show evidence of metal debris. There was one non-revision reoperation (open subscapularis exploration), one shoulder with anterosuperior escape, three shoulders with glenoid radiolucencies indicative of possible glenoid loosening, and nine shoulders with superior migration of the humeral head (>2mm migration at final follow-up compared to immediate postoperative). When comparing postoperative scores between patients with vs without metal debris, we found no statistically significant difference in the EQ5D VAS, WOOS Index, ASES Score and CS. On further analyses, when comparing superior migration of the humeral head and postoperative outcomes scores, we found no statistically significant difference. We report the longest published follow-up with clinical and radiographic outcomes of second-generation porous tantalum glenoid anatomic shoulder arthroplasties. In this series of patients, 45% of total shoulder arthroplasties with a second-generation porous tantalum glenoid implant had radiographic evidence of metal debris. This metal debris was not statistically associated with poorer postoperative outcomes. Further investigation and ongoing follow-up are warranted

Total shoulder arthroplasty (TSA) is an excellent surgical solution for patients with shoulder arthritis, providing good to excellent results in the vast majority of patients. Complications are rare, however, when they occur, can be devastating for both the patient and surgeon. An increasingly recognised complication of TSA is glenoid component failure. In a recent review of nearly 4000 shoulder arthroplasties, symptomatic glenoid component loosening occurs at a rate of 1.2% per year, while asymptomatic radiolucent lines occur at a rate of 7.3% per year. In addition, keeled glenoid components have been found to have an increased incidence of radiolucent lines compared to pegged glenoid components at both short and longer-term follow-up. Further, pegged glenoid components are associated with a lower risk of revision arthroplasty compared to keeled glenoid components. In a separate study of approximately 4600 shoulder arthroplasties, metal-backed glenoid components were found to have significantly lower rates of radiolucent lines, radiographic loosening, and component failure compared to all-polyethylene glenoid components. Despite these findings, however, metal-backed components are significantly more likely to require revision surgery (3:1) compared to all-polyethylene components. For the failed TSA due to glenoid component failure, revision with glenoid reimplantation may be considered, but is associated with a high rate of recurrent glenoid loosening. Alternatively, revision to a reverse shoulder arthroplasty, is feasible, but is technically demanding with high complication and reoperation rates. This paper will discuss the etiology, work-up, and treatment of patients with glenoid component failure following TSA

Purpose: The causes of glenoid loosening are multifactorial (implant design, surgical technique, bone properties, soft tissue properties). This biomechanical study was conducted to evaluate the consequences of two clinical problems often encountered in shoulder arthroplasty: subscapular tension and glenoid retroversion. Material and methods: We developed a 3D model of the shoulder including the rotator cuff. A total prosthesis was implanted by digital modellisation. The humeral prosthesis imitated the adaptable third-generation implants, with a stem and a portion of a metal sphere, were used to achieve anatomic reconstruction of the proximal humerus. The polyethylene glenoid, cemented to bone, had a central stem and a flat base. Two subscapular tension (normal and twice normal) and two glenoid positions (0° and 20° retroversion) were tested. External rotation (0–40°) and internal rotation (0–60°) were simulated. We calculated displacement of the glenohumeral contact point, joint forces and contact pressures, interosseous glenoid stress, and micromovement of the bone-cement-implant interfaces. Results: Subscapular tension produced increased forces and joint pressures, associated with moderate posterior translation of the glenohumeral contact point. Retroversion induced more marked posterior displacement of the contact point, leading to significantly higher intraosseous glenoid stress and micromovements at the interfaces. The association of subscapular tension and glenoid retroversion produced important concentration of stress forces in the posterior part of the glenoid and increased all the micromovements. Discussion: Subscapular tension and retroversion of the glenoid implant have significant biomechanical effects which can favour glenoid loosening. Correction of these two parameters must be carefully controlled during shoulder arthroplasty

Lateralizing the center of rotation in reverse shoulder arthroplasty has been the subject of renewed interest due to complications associated with medialized center of rotation implants. Benefits of lateralization include: increased joint stability, decreased incidence of scapular notching, increased range of motion, and cosmetic appeal. However, lateralization may be associated with increased risk of glenoid loosening, which may result from the increased shear forces and the bending stresses that manifest at the bone-implant interface. To address glenoid loosening in reverse implants with lateralized joint centers, recent studies have focused on testing and improving implant fixation. However, these studies use loads derived from literature specific to subjects with normal anatomy. The aim of this study is to characterize how joint center lateralization affects the loading in reverse shoulder arthroplasty. Using an established computational shoulder model that describes the geometry of a commercial reverse prosthesis (DELTA® III, DePuy), motion in abduction, scapular plane elevation, and forward flexion was simulated. The simulations were run for five progressively lateralized centers of rotation: −5, 0, +5, +10, and +15 mm (Figure 1). The model was modified to simulate a full thickness rotator cuff tear, where all cuff musculature except Teres Minor were excluded, to reflect the clinical indication for reverse shoulder arthroplasty on cuff tear arthropathy patients. To analyze the joint contact forces, the resultant glenohumeral force was decomposed into compression, anterior-posterior shear, and superior-inferior shear on the glenoid. Joint center lateralization was found to affect the glenohumeral joint contact forces and glenoid loads increased by up to 18% when the center was lateralized from −5 mm to +15 mm. Compressive forces were found to be more sensitive to lateralization in abduction, while changes in shear forces were more affected in forward flexion and scapular plane abduction. On average, the superior shear component showed the largest increases due to lateralization (up to a 21% increase), while the anterior-posterior shear component showed larger changes than those of compression, except in the most lateralized center position (Figure 2). The higher joint loads in the lateralized joint centers reflect a shortening of the Deltoid muscle moment arms (Figure 3), since the muscle needs to exert more force to provide the desired motions. The additional shear forces generated by the lateralization may increase the risk of the ‘rocking-horse’ effect. Together with the lateralized joint center, this creates an additional bending stress at the bone-implant interface that puts the implant at further risk of loosening (Figure 1). Current studies on implant fixation tend to use loads in compression and superior shear that exceed the forces seen in this study but have not investigated anterior-posterior shear loads. Our data support that loading in anterior-posterior direction can be significant. Using inappropriate loads to design fixation may result in excessive loss of bone stock and/or unforeseen implant loosening. The implication is that future studies may be performed using this more relevant data set to navigate the tradeoff between fixation and bone conservation

Glenoid component loosening is a concern in long term outcome of total shoulder arthroplasty. Unfortunately revision of glenoid loosening remains very challenging regarding bone reconstruction and reimplantation of a glenoid component. A new design metal-back component (Arrow™) seems to get the procedure easier and lead to higly best clinical and radiological results than prior technics. It is a retrospective study of 34 patients operated on for isolated aseptic glenoid component loosening between 1997 and 2007. Glenoid bone loss based on a new classification was rated in 5 degrees. All patients were reviewed at a mean follow up of 34 months (from 12 to 89). Pre and post operatively Constant score and SST have been evaluated. Fluoroscopic views and CT scan have been performed for radiologic assesment. Mean delay for revision surgery was 58 months (from 28 to 134 months). 16 patients underwent only bone graft reconstruction. 18 patients underwent both bone reconstruction and glenoid implant reimplantation. Autolog bone graft (iliac crest) was used in 19 cases, allograft bone in 5 cases, and both autolog and dried bone substitutes in 10 cases. The glenoid component was an uncemented metal-backed in 11 cases, and a polyethylene cemented in 2 cases. The new metal-backed bone ingrowth component is composed with a keel and a winglet securing bone graft fixation and implant stability. For the all cohort Constant score improves of 21 points (from 35 to 56). Gain of pain and active motion is statiscally significative (p< 0.005).Patients who underwent reimplantation of a new glenoid component had a higher clinical result (Constant score: 66) than those who underwent only a bone graft reconstruction (Constant score: 52) in term of pain and active forward elevation as well (p< 0.001). At maximum follow up (32 months) no radiolucent lines or loosening of the new glenoid component was noted. Patients who underwent only bone reconstruction showed a mild glenoid erosion due to subsidence and resorption of cancellous auto or allograft bone. Revision of glenoid component depends on the glenoid bone stock specially about posterior defect. The use of cortical autolog bone graft and new metalback component allows better glenoid reconstruction, secure the stabiliy of the new gle and yields to goods clinical results restoring painless shoulder and function. Reimplantation of a glenoid component becomes an adequate procedure for total shoulder arthroplasty revision

Background. Glenoid component aseptic loosening is the most common source of total shoulder arthroplasty (TSA) revision. In an attempt to strengthen cemented glenoid component fixation, divergent pegged glenoids were designed. Divergent peg creation was intended to increase cement purchase and provide resistance to component rocking. Methods. Thirty-four patients who underwent divergent peg TSA had data collected prospectively. The data from these patients was retrospectively reviewed, primarily for radiographic evidence of glenoid component loosening. The endpoint was defined as the need for revision secondary to glenoid loosening. Secondary outcome measures such as SPADI (shoulder pain and disability index), active forward elevation, abduction, internal rotation, and external rotation were also collected. Data was obtained preoperatively and at the following postoperative intervals: 3 months, 6 months, and yearly. The last available postoperative radiographs were also reviewed and graded on a modified Franklin glenoid lucency scale described by Lazarus et al. Results. The mean follow-up was 5.6 years ± 2.44 (range, 2–10 years). Of the 34 patients in the study, 20 patients had radiographs available for review. Radiographs showed complete lucency around one or less pegs in 14/20 patients (grade 0–2). Six out of twenty glenoids had complete radiolucency around two or more pegs with gross loosening seen in one shoulder (grade 3–5). No secondary surgery was performed in any patients. Significant improvements were seen in active elevation 30.2 degrees ±44.3 (p=0.043) at the last follow up. Improvement was also seen in internal rotation of 4.3 levels ± 4.9 (p=0.016) at the last follow-up. The mean postoperative SPADI score decreased by 48.1 points (p=0.039). Conclusions. Patients with divergent pegged glenoid TSA showed significant improvement in postoperative shoulder elevation, internal rotation, and SPADI scores at final follow-up. No patients underwent revision. However, there were a significant number of patients with radiolucency seen around 2 or more pegs

Aims

Optimal glenoid positioning in reverse shoulder arthroplasty (RSA) is crucial to provide impingement-free range of motion (ROM). Lateralization and inclination correction are not yet systematically used. Using planning software, we simulated the most used glenoid implant positions. The primary goal was to determine the configuration that delivers the best theoretical impingement-free ROM.