Aims. This study aimed to assess the impact of using the metal-augmented glenoid baseplate (AGB) on improving clinical and radiological outcomes, as well as reducing complications, in patients with superior glenoid wear undergoing reverse shoulder arthroplasty (RSA). Methods. From January 2016 to June 2021, out of 235 patients who underwent primary RSA, 24 received a superior-AGB after off-axis reaming (Group A). Subsequently, we conducted propensity score matching in a 1:3 ratio, considering sex, age, follow-up duration, and glenoid wear (superior-inclination and retroversion), and selected 72 well-balanced matched patients who received a standard glenoid baseplate (STB) after eccentric reaming (Group B). Superior-inclination, retroversion, and lateral humeral offset (LHO) were measured to assess preoperative glenoid wear and postoperative correction, as well as to identify any complications. Clinical outcomes were measured at each outpatient visit before and after surgery. Results. There were no significant differences in demographic data and preoperative characteristics between the two groups. Both groups showed significant improvements in patient-reported outcome measures (visual analogue scale for pain, visual analogue scale for function, American Shoulder and Elbow Surgeons, Constant, and Simple Shoulder Test scores) from preoperative to final assessment (p < 0.001). However, AGB showed no additional benefit. Notably, within range of motion, Group B showed significant postoperative decrease in both external rotation and internal rotation, unlike Group A (p = 0.028 and 0.003, respectively). Both groups demonstrated a significant correction of superior-inclination after surgery, while patients in Group B exhibited a significant decrease in LHO postoperatively (p = 0.001). Regarding complications, Group A experienced more acromial stress fractures (3 cases; 12.5%), whereas Group B had a higher occurrence of scapular notching (24 cases; 33.3%) (p = 0.008). Conclusion. Both eccentric reaming with STB and off-axis reaming with AGB are effective methods for addressing superior glenoid wear in RSA, leading to improved clinical outcomes. However, it is important to be aware of the potential risks associated with eccentric reaming, which include excessive bone loss leading to reduced rotation and scapular notching. Cite this article: Bone Joint J 2024;106-B(3):268–276

Aims. Accurate measurement of the glenoid version is important in performing total shoulder arthroplasty (TSA). Our aim was to evaluate the Ellipse method, which involves formally defining the vertical mid-point of the glenoid prior to measuring the glenoid version and comparing it with the ‘classic’ Friedman method. Methods. This was a retrospective study which evaluated 100 CT scans for patients who underwent a primary TSA. The glenoid version was measured using the Friedman and Ellipse methods by two senior observers. Statistical analyses were performed using the paired t-test for significance and the Bland-Altman plot for agreement. Results. The mean glenoid version was -3.11° (-23.8° to 17.9°) using the Friedman method and -1.95° (-29.8° to 24.6°) using the Ellipse method (p = 0.002). In 16 patients the difference between methods was greater than 5°, which we considered to be clinically significant. There was poor agreement between methods with relatively large 95% limits of agreement. There was excellent inter-rater agreement between the observers for the Ellipse method and similarly, the intrarater agreement was excellent with a repeatability coefficient of 0.94. Conclusion. We recommend the use of the Ellipse modification to define the mid glenoid point prior to measuring the glenoid version in patients undergoing TSA. Cite this article: Bone Joint J 2020;102-B(2):232–238

Aims. The Walch Type C dysplastic glenoid is characterized by excessive retroversion. This anatomical study describes its morphology. Patients and Methods. A total of 29 shoulders with a dysplastic glenoid were analyzed. CT was used to measure retroversion, inclination, height, width, radius-of-curvature, surface area, depth, subluxation of the humeral head and the Goutallier classification of fatty infiltration. The severity of dysplasia and deficiency of the posterior rim of the glenoid were recorded. Results. A type C glenoid occurred in 1.8% of shoulders referred to our tertiary centres. The mean retroversion, inclination, height, width, radius-of-curvature, surface area, and depth of the glenoid were 37°, 3°, 46 mm, 30 mm, 37°, 1284 mm. 3. , and 16 mm, respectively. The mean posterior subluxation was 90%. The Goutallier class was < 2 in 25 shoulders (86%). Glenoid dysplasia was mild in four, moderate in 14, and severe in 11 shoulders. The typical appearance of the posterior glenoid rim had a rounded or ‘lazy J’ morphology. The glenoid neck was deficient in 18 shoulders (62%). Conclusion. A dysplastic Type C glenoid characteristically has a uniconcave retroverted morphology, a deficient posteroinferior rim and scapular neck, and a reduced depth. These findings help to define the unique anatomical variations and may aid the planning of surgery and the development of components for these patients. Cite this article: Bone Joint J 2018;100-B:1074–9

Aims. We present our experience of using a metal-backed prosthesis and autologous bone graft to treat gross glenoid bone deficiency. Patients and Methods. A prospective cohort study of the first 45 shoulder arthroplasties using the SMR Axioma Trabecular Titanium (TT) metal-backed glenoid with autologous bone graft. Between May 2013 and December 2014, 45 shoulder arthroplasties were carried out in 44 patients with a mean age of 64 years (35 to 89). The indications were 23 complex primary arthroplasties, 12 to revise a hemiarthroplasty or resurfacing, five for aseptic loosening of the glenoid, and five for infection. Results. Of the 45 patients, 16 had anatomical shoulder arthroplasties (ASA) and 29 had reverse shoulder arthroplasties (RSA). Postoperatively, 43/45 patients had a CT scan. In 41 of 43 patients (95%), the glenoid peg achieved > 50% integration. In 40 of 43 cases (93%), the graft was fully or partially integrated. There were seven revisions (16%) but only four (9%) required a change of baseplate. Four (25%) of the 16 ASAs were revised for instability or cuff failure. At two-year radiological follow-up, five of the 41 cases (11%) showed some evidence of lucent lines. Conclusion. The use of a metal baseplate with a trabecular titanium surface in conjunction with autologous bone graft is a reliable method of addressing glenoid bone defects in primary and revision RSA setting in the short term. ASAs have a higher rate of complications with this technique

Osteoarthritis results in changes in the dimensions of the glenoid. This study aimed to assess the size and radius of curvature of arthritic glenoids. A total of 145 CT scans were analysed, performed as part of routine pre-operative assessment before total shoulder replacement in 91 women and 54 men. Only patients with primary osteoarthritis and a concentric glenoid were included in the study. The CT scans underwent three-dimensional (3D) reconstruction and were analysed using dedicated computer software. The measurements consisted of maximum superoinferior height, anteroposterior width and a best-fit sphere radius of curvature of the glenoid. The mean height was 40.2 mm (. sd. 4.9), the mean width was 29 mm (. sd. 4.3) and the mean radius of curvature was 35.4 mm (. sd. 7.8). The measurements were statistically different in men and women and had a Gaussian distribution with marked variation. All measurements were greater than the known values in normal subjects. With current shoulder replacement systems using a unique backside radius of curvature for the glenoid component, there is a risk of undertaking excessive reaming to adapt the bone to the component resulting in sacrifice of subchondral bone or under-reaming and instability of the component due to a ’rocking horse‘ phenomenon. . Cite this article: Bone Joint J 2013;95-B:1377–82

Pre-operative 3D glenoid planning improves component placement in terms of version, inclination, offset and orientation. Version and inclination measurements require the position of the inferior angle. As a consequence, current planning tools require a 3D model of the full scapula to accurately determine the glenoid parameters. Statistical shape models (SSMs) can be used to reconstruct the missing anatomy of bones. Therefore, the objective of this study is to develop and validate an SSM for the reconstruction of the inferior scapula, hereby reducing the irradiation exposure for patients. The training dataset for the statistical shape consisted of 110 CT images from patients without observable scapulae pathologies as judged by an experienced shoulder surgeon. 3D scapulae models were constructed from the segmented images. An open-source non-rigid B-spline-based registration algorithm was used to obtain point-to-point correspondences between the models. A statistical shape model was then constructed from the dataset using principal component analysis. Leave-one-out cross-validation was performed to evaluate the accuracy of the predicted glenoid parameters from virtual partial scans. Five types of virtual partial scans were created on each of the training set models, where an increasing amount of scapular body was removed to mimic a partial CT scan. The statistical shape model was reconstructed using the leave-one-out method, so the corresponding training set model is no longer incorporated in the shape model. Reconstruction was performed using a Monte Carlo Markov chain algorithm, random walk proposals included both shape and pose parameters, the closest fitting proposal was selected for the virtual reconstruction. Automatic 3D measurements were performed on both the training and reconstructed 3D models, including glenoid version, inclination, glenoid centre point position and glenoid offset. In terms of inclination and version we found a mean absolute difference between the complete model and the different virtual partial scan models of 0.5° (SD 0.4°). The maximum difference between models was 3° for inclination and 2° for version. For offset and centre point position the mean absolute difference was 0 mm with an absolute maximum of 1 mm. The magnitude of the mean and maximum differences for all anatomic measurements between the partial scan and complete models is smaller than the current surgical accuracy. Considering these findings, we believe a SSM based reconstruction technique can be used to accurately reconstruct the glenoid parameters from partial CT scans

The aim of this study was to compare a third-generation cementing procedure for glenoid components with a new technique for cement pressurisation. In 20 pairs of scapulae, 20 keeled and 20 pegged glenoid components were implanted using either a third-generation cementing technique (group 1) or a new pressuriser (group 2). Cement penetration was measured by three-dimensional (3D) analysis of micro-CT scans. The mean 3D depth of penetration of the cement was significantly greater in group 2 (p < 0.001). The mean thickness of the cement mantle for keeled glenoids was 2.50 mm (2.0 to 3.3) in group 1 and 5.18 mm (4.4 to 6.1) in group 2, and for pegged glenoids it was 1.72 mm (0.9 to 2.3) in group 1 and 5.63 mm (3.6 to 6.4) in group 2. A cement mantle < 2 mm was detected less frequently in group 2 (p < 0.001). Using the cement pressuriser the proportion of cement mantles < 2 mm was significantly reduced compared with the third-generation cementing technique

Osteochondral glenoid loss is associated with recurrent shoulder instability. The critical threshold for surgical stabilization is multidimensional and conclusively unknown. The aim of this work was to provide a well- measurable surrogate parameter of an unstable shoulder joint for the frequent anterior-inferior dislocation direction. The shoulder stability ratio (SSR) of 10 paired human cadaveric glenoids was determined in anterior-inferior dislocation direction. Osteochondral defects were simulated by gradually removing osteochondral structures in 5%-stages up to 20% of the intact diameter. The glenoid morphological parameters glenoid depth, concavity gradient, and defect radius were measured at each stage by means of optical motion tracking. Based on these parameters, the osteochondral stability ratio (OSSR) was calculated. Correlation analyses between SSR and all morphological parameters, as well as OSSR were performed. The loss of SSR, concavity gradient, depth and OSSR with increasing defect size was significant (all p<0.001). The loss of SSR strongly correlated with the losses of concavity gradient (PCC = 0.918), of depth (PCC = 0.899), and of OSSR (PCC = 0.949). In contrast, the percentage loss based on intact diameter (defect size) correlated weaker with SSR (PCC=0.687). Small osteochondral defects (≤10%) led to significantly higher SSR decrease in small glenoids (diameter <25mm) compared to large (≥ 25mm) ones (p ≤ 0.009). From a biomechanical perspective, the losses of concavity gradient, glenoid depth and OSSR correlate strong with the loss of SSR. Therefore, especially the loss of glenoidal depth may be considered as a valid and reliable alternative parameter to describe shoulder instability. Furthermore, smaller glenoids are more vulnerable to become unstable in case of small osteochondral loosening. On the other hand, the standardly used percentage defect size based on intact diameter correlates weaker with the magnitude of instability and may therefore not be a valid parameter for judgement of shoulder instability

Aims. The aim of this study was to determine whether there is a correlation between the grade of humeral osteoarthritis (OA) and the severity of glenoid morphology according to Walch. We hypothesized that there would be a correlation. Methods. Overal, 143 shoulders in 135 patients (73 females, 62 males) undergoing shoulder arthroplasty surgery for primary glenohumeral OA were included consecutively. Mean age was 69.3 years (47 to 85). Humeral head (HH), osteophyte length (OL), and morphology (transverse decentering of the apex, transverse, or coronal asphericity) on radiographs were correlated to the glenoid morphology according to Walch (A1, A2, B1, B2, B3), glenoid retroversion, and humeral subluxation on CT images. Results. Increased humeral OL correlated with a higher grade of glenoid morphology (A1-A2-B1-B2-B3) according to Walch (r = 0.672; p < 0.0001). It also correlated with glenoid retroversion (r = 0.707; p < 0.0001), and posterior humeral subluxation (r = 0.452; p < 0.0001). A higher humeral OL (odds ratio (OR) 1.17; 95% confidence interval (CI) 1.03 to 1.32; p = 0.013), posterior humeral subluxation (OR 1.11; 95% CI 1.01 to 1.22; p = 0.031), and glenoid retroversion (OR 1.48; 95% CI 1.30 to 1.68; p < 0.001) were independent factors for a higher glenoid morphology. More specifically, a humeral OL of ≥ 13 mm was indicative of eccentric glenoid types B2 and B3 (OR 14.20; 95% CI 5.96 to 33.85). Presence of an aspherical HH in the coronal plane was suggestive of glenoid types B2 and B3 (OR 3.34; 95% CI 1.67 to 6.68). Conclusion. The criteria of humeral OL and HH morphology are associated with increasing glenoid retroversion, posterior humeral subluxation, and eccentric glenoid wear. Therefore, humeral radiological parameters might hint at the morphology on the glenoid side. Cite this article: Bone Jt Open 2022;3(6):463–469

Aims. We report the clinical results of glenoid osteotomy in patients with atraumatic posteroinferior instability associated with glenoid dysplasia. Patients and Methods. The study reports results in 211 patients (249 shoulders) with atraumatic posteroinferior instability. The patients comprised 63 men and 148 women with a mean age of 20 years. The posteroinferior glenoid surface was elevated by osteotomy at the scapular neck. A body spica was applied to maintain the arm perpendicular to the glenoid for two weeks postoperatively. Clinical results were evaluated using the Rowe score and Japan Shoulder Society Shoulder Instability Score (JSS-SIS); bone union, osteoarthrosis, and articular congruity were examined on plain radiographs. Results. The Rowe score improved from 36 to 88 points, and the JSS-SIS improved from 47 to 81 points. All shoulders exhibited union without progression of osteoarthritis except one shoulder, which showed osteoarthritic change due to a previous surgery before the glenoid osteotomy. All but three shoulders showed improvement in joint congruency. Eight patients developed disordered scapulohumeral rhythm during arm elevation, and 12 patients required additional open stabilization for anterior instability. Conclusion. Good results can be expected from glenoid osteotomy in patients with atraumatic posteroinferior instability associated with glenoid dysplasia. Cite this article: Bone Joint J 2018;100-B:331–7

Aims. Glenoid bone loss can be a challenging problem when revising a shoulder arthroplasty. Precise pre-operative planning based on plain radiographs or CT scans is essential. We have investigated a new radiological classification system to describe the degree of medialisation of the bony glenoid and that will indicate the amount of bone potentially available for supporting a glenoid component. It depends on the relationship between the most medial part of the articular surface of the glenoid with the base of the coracoid process and the spinoglenoid notch: it classifies the degree of bone loss into three types. It also attempts to predict the type of glenoid reconstruction that may be possible (impaction bone grafting, structural grafting or simple non-augmented arthroplasty) and gives guidance about whether a pre-operative CT scan is indicated. Patients and Methods. Inter-method reliability between plain radiographs and CT scans was assessed retrospectively by three independent observers using data from 39 randomly selected patients. . Inter-observer reliability and test-retest reliability was tested on the same cohort using Cohen's kappa statistics. Correlation of the type of glenoid with the Constant score and its pain component was analysed using the Kruskal-Wallis method on data from 128 patients. Anatomical studies of the scapula were reviewed to explain the findings. Results. Excellent inter-method reliability, inter-observer and test-retest reliability were seen. The system did not correlate with the Constant score, but correlated well with its pain component. . Take home message: Our system of classification is a helpful guide to the degree of glenoid bone loss when embarking on revision shoulder arthroplasty. Cite this article: Bone Joint J 2016;98-B:374–80

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. Due to the predictability of outcomes achieved with reverse shoulder arthroplasty (rTSA), rTSA is increasingly being used in patients where glenoid fixation is compromised due to presence of glenoid wear. There are various methods to achieve glenoid fixation in patients with glenoid wear, including the use of bone grafting behind the glenoid baseplate or the use of augmented glenoid baseplates. This clinical study quantifies clinical outcomes achieved using both techniques in patients with severe glenoid wear at 2 years minimum follow-up. Methods. 80 patients (mean age: 71.6yrs) with 2 years minimum follow-up were treated by 7 fellowship trained orthopaedic surgeons using rTSA with bone graft behind the baseplate or rTSA with an augmented glenoid baseplate in patients with severe posterior glenoid wear. 39 rTSA patients (14 female, avg: 73.1 yrs; 25 male, avg: 71.5 yrs) received an augmented glenoid (cohort composed of 24 patients with an 8° posterior augment baseplate and 15 patients with a 10° superior augment baseplate) for treatment of CTA, RCT, and OA with a medially eroded scapula. 41 rTSA patients (27 female, avg: 73.0 yrs; 14 male, avg: 66.9 yrs) received glenoid bone graft (cohort composed of 5 patients with allograft and 36 patients with autograft) for treatment of CTA, RCT, and OA with a medially eroded scapula. Outcomes were scored using SST, UCLA, ASES, Constant, and SPADI metrics; active abduction, forward flexion, and internal/external rotation were also measured to quantify function. Average follow-up was 31.2 months (augment 28.3; graft 34.1). A two-tailed, unpaired t-test identified differences (p<0.05) in pre-operative, post-operative, and pre-to-post improvements. Results. A comparison of pre-operative, post-operative, and pre-to-post improvement in outcomes are presented in Tables 1–3, respectively. No difference was noted in pre-operative, post-operative, and pre-to-post improvement in outcomes between cohorts. The augmented glenoid baseplate rTSA cohort had 0 complications for a complication rate of 0%; whereas, the rTSA glenoid bone graft cohort had 6 complications (including 2 glenoid loosenings/graft failures) for a complication rate of 14.6%. Additionally, radiographic follow-up information was available for 30 of 39 augmented baseplate patients (76.9%) and 27 of 41 bone graft patients (65.9%); where the augmented baseplate rTSA cohort had a scapular notching rate of 10.0% with an average scapular notching grade of 0.1; whereas, the rTSA glenoid bone graft cohort had a scapular notching rate of 18.5% with an average scapular notching grade of 0.19. Conclusions. These results demonstrate positive outcomes can be achieved at 2 years minimum follow-up in patients with severe glenoid wear using either augmented glenoid baseplates or bone graft behind the glenoid baseplate with rTSA. While no statistical difference was noted between pre-operative, post-operative, and pre-to-post improvement in outcomes between rTSA cohorts, a substantial difference in the complication rate was noted between cohorts which may factor into the surgeon's decision of the choice of treatment technique for these patients. Additional and longer-term follow-up is needed to confirm these outcomes and trends

Aims. The current evidence comparing the two most common approaches for reverse total shoulder arthroplasty (rTSA), the deltopectoral and anterosuperior approach, is limited. This study aims to compare the rate of loosening, instability, and implant survival between the two approaches for rTSA using data from the Dutch National Arthroplasty Registry with a minimum follow-up of five years. Methods. All patients in the registry who underwent a primary rTSA between January 2014 and December 2016 using an anterosuperior or deltopectoral approach were included, with a minimum follow-up of five years. Cox and logistic regression models were used to assess the association between the approach and the implant survival, instability, and glenoid loosening, independent of confounders. Results. In total, 3,902 rTSAs were included. A deltopectoral approach was used in 54% (2,099/3,902) and an anterosuperior approach in 46% (1,803/3,902). Overall, the mean age in the cohort was 75 years (50 to 96) and the most common indication for rTSA was cuff tear arthropathy (35%; n = 1,375), followed by osteoarthritis (29%; n = 1,126), acute fracture (13%; n = 517), post-traumatic sequelae (10%; n = 398), and an irreparable cuff rupture (5%; n = 199). The two high-volume centres performed the anterosuperior approach more often compared to the medium- and low-volume centres (p < 0.001). Of the 3,902 rTSAs, 187 were revised (5%), resulting in a five-year survival of 95.4% (95% confidence interval 94.7 to 96.0; 3,137 at risk). The most common reason for revision was a periprosthetic joint infection (35%; n = 65), followed by instability (25%; n = 46) and loosening (25%; n = 46). After correcting for relevant confounders, the revision rate for glenoid loosening, instability, and the overall implant survival did not differ significantly between the two approaches (p = 0.494, p = 0.826, and p = 0.101, respectively). Conclusion. The surgical approach used for rTSA did not influence the overall implant survival or the revision rate for instability or glenoid loosening. Cite this article: Bone Joint J 2023;105-B(9):1000–1006

Aims. The aim of this study was to longitudinally compare the clinical and radiological outcomes of anatomical total shoulder arthroplasty (aTSA) up to long-term follow-up, when using cemented keel, cemented peg, and hybrid cage peg glenoid components and the same humeral system. Methods. We retrospectively analyzed a multicentre, international clinical database of a single platform shoulder system to compare the short-, mid-, and long-term clinical outcomes associated with three designs of aTSA glenoid components: 294 cemented keel, 527 cemented peg, and 981 hybrid cage glenoids. Outcomes were evaluated at 4,746 postoperative timepoints for 1,802 primary aTSA, with a mean follow-up of 65 months (24 to 217). Results. Relative to their preoperative condition, each glenoid cohort had significant improvements in clinical outcomes from two years to ten years after surgery. Patients with cage glenoids had significantly better clinical outcomes, with higher patient-reported outcome scores and significantly increased active range of motion, compared with those with keel and peg glenoids. Those with cage glenoids also had significantly fewer complications (keel: 13.3%, peg: 13.1%, cage: 7.4%), revisions (keel: 7.1%, peg 9.7%, cage 3.5%), and aseptic glenoid loosening and failure (keel: 4.7%, peg: 5.8%, cage: 2.5%). Regarding radiological outcomes, 70 patients (11.2%) with cage glenoids had glenoid radiolucent lines (RLLs). The cage glenoid RLL rate was 3.3-times (p < 0.001) less than those with keel glenoids (37.3%) and 4.6-times (p < 0.001) less than those with peg glenoids (51.2%). Conclusion. These findings show that good long-term clinical and radiological outcomes can be achieved with each of the three aTSA designs of glenoid component analyzed in this study. However, there were some differences in clinical and radiological outcomes: generally, cage glenoids performed best, followed by cemented keel glenoids, and finally cemented peg glenoids. Cite this article: Bone Joint J 2023;105-B(6):668–678

Aims. Reverse total shoulder arthroplasty (rTSA) can be used in complex cases when the glenoid requires reconstruction. In this study, a baseplate with composite bone autograft and a central trabecular titanium peg was implanted, and its migration was assessed for two years postoperatively using radiostereometric analysis (RSA). Methods. A total of 14 patients who underwent a rTSA with an autograft consented to participate. Of these, 11 had a primary rTSA using humeral head autograft and three had a revision rTSA with autograft harvested from the iliac crest. The mean age of the patients was 66 years (39 to 81). Tantalum beads were implanted in the scapula around the glenoid. RSA imaging (stereographic radiographs) was undertaken immediately postoperatively and at three, six, 12, and 24 months. Analysis was completed using model-based RSA software. Outcomes were collected preoperatively and at two years postoperatively, including the Oxford Shoulder Score, the American Shoulder and Elbow Score, and a visual analogue score for pain. A Constant score was also obtained for the assessment of strength and range of motion. Results. RSA analysis showed a small increase in all translation and rotational values up to six months postoperatively, consistent with settling of the implant. The mean values plateaued by 12 months, with no evidence of further migration. In four patients, there was significant variation outside the mean, which corresponded to postoperative complications. There was a significant improvement in the clinical and patient-reported outcomes from the preoperative values to those at two years postoperatively (p < 0.001). Conclusion. These findings show, using RSA, that a glenoid baseplate composite of a trabecular titanium peg with autograft stabilizes within the glenoid about 12 months after surgery, and reinforce findings from a previous study of this implant/graft with CT scans at two years postoperatively, indicating that this type of structural composite results in sound early fixation. Cite this article: Bone Joint J 2023;105-B(8):912–919

Knowledge of the premorbid glenoid shape and the morphological changes the bone undergoes in patients with glenohumeral arthritis can improve surgical outcomes in total and reverse shoulder arthroplasty. Several studies have previously used scapular statistical shape models (SSMs) to predict premorbid glenoid shape and evaluate glenoid erosion properties. However, current literature suggests no studies have used scapular SSMs to examine the changes in glenoid surface area in patients with glenohumeral arthritis. Therefore, the purpose of this study was to compare the glenoid articular surface area between pathologic glenoid cavities from patients with glenohumeral arthritis and their predicted premorbid shape using a scapular SSM. Furthermore, this study compared pathologic glenoid surface area with that from virtually eroded glenoid models created without influence from internal bone remodelling activity and osteophyte formation. It was hypothesized that the pathologic glenoid cavities would exhibit the greatest glenoid surface area despite the eroded nature of the glenoid and the medialization, which in a vault shape, should logically result in less surface area. Computer tomography (CT) scans from 20 patients exhibiting type A2 glenoid erosion according to the Walch classification [Walch et al., 1999] were obtained. A scapular SSM was used to predict the premorbid glenoid shape for each scapula. The scapula and humerus from each patient were automatically segmented and exported as 3D object files along with the scapular SSM from a pre-operative planning software. Each scapula and a copy of its corresponding SSM were aligned using the coracoid, lateral edge of the acromion, inferior glenoid tubercule, scapular notch, and the trigonum spinae. Points were then digitized on both the pathologic humeral and glenoid surfaces and were used in an iterative closest point (ICP) algorithm in MATLAB (MathWorks, Natick, MA, USA) to align the humerus with the glenoid surface. A Boolean subtraction was then performed between the scapular SSM and the humerus to create a virtual erosion in the scapular SSM that matched the erosion orientation of the pathologic glenoid. This led to the development of three distinct glenoid models for each patient: premorbid, pathologic, and virtually eroded (Fig. 1). The glenoid surface area from each model was then determined using 3-Matic (Materialise, Leuven, Belgium). Figure 1. (A) Premorbid glenoid model, (B) pathologic glenoid model, and (C) virtually eroded glenoid model. The average glenoid surface area for the pathologic scapular models was 70% greater compared to the premorbid glenoid models (P < 0 .001). Furthermore, the surface area of the virtual glenoid erosions was 6.4% lower on average compared to the premorbid glenoid surface area (P=0.361). The larger surface area values observed in the pathologic glenoid cavities suggests that sufficient bone remodelling exists at the periphery of the glenoid bone in patients exhibiting A2 type glenohumeral arthritis. This is further supported by the large difference in glenoid surface area between the pathologic and virtually eroded glenoid cavities as the virtually eroded models only considered humeral anatomy when creating the erosion. For any figures or tables, please contact the authors directly

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

Aims. Reverse total shoulder arthroplasty (RTSA) using trabecular metal (TM)-backed glenoid implants has been introduced with the aim to increase implant survival. Only short-term reports on the outcomes of TM-RTSA have been published to date. We aim to present the seven-year survival of TM-backed glenoid implants along with minimum five-year clinical and radiological outcomes. Methods. All consecutive elective RTSAs performed at a single centre between November 2008 and October 2014 were reviewed. Patients who had primary TM-RTSA for rotator cuff arthropathy and osteoarthritis with deficient cuff were included. A total of 190 shoulders in 168 patients (41 male, 127 female) were identified for inclusion at a mean of 7.27 years (SD 1.4) from surgery. The primary outcome was survival of the implant with all-cause revision and aseptic glenoid loosening as endpoints. Secondary outcomes were clinical, radiological, and patient-related outcomes with a five-year minimum follow-up. Results. The implant was revised in ten shoulders (5.2%) with a median time to revision of 21.2 months (interquartile range (IQR) 9.9 to 41.8). The Kaplan-Meier survivorship estimate at seven years was 95.9% (95% confidence interval (CI) 91.7 to 98; 35 RTSAs at risk) for aseptic mechanical failure of the glenoid and 94.8% (95% CI 77.5 to 96.3; 35 RTSAs at risk) for all-cause revision. Minimum five-year clinical and radiological outcomes were available for 103 and 98 RTSAs respectively with a median follow-up time of six years (IQR 5.2 to 7.0). Median postoperative Oxford Shoulder Score was 38 (IQR 31 to 45); median Constant and Murley score was 60 (IQR 47.5 to 70); median forward flexion 115° (IQR 100° to 125°); median abduction 95° (IQR 80° to 120°); and external rotation 25° (IQR 15° to 40°) Scapular notching was seen in 62 RTSAs (63.2%). Conclusion. We present the largest and longest-term series of TM-backed glenoid implants demonstrating 94.8% all-cause survivorship at seven years. Specifically pertaining to glenoid loosening, survival of the implant increased to 95.9%. In addition, we report satisfactory minimum five-year clinical and radiological outcomes. Cite this article: Bone Joint J 2021;103-B(8):1333–1338

Purpose of the study: Posterior glenoid erosio is a common finging in patients with degenerative joint disease of the shoulder. Anterior release is usually recommended, almost always with correction of the glenoid retroversion. There is no real consensus on the gravity of these posterior lesions nor on the appropriate attitude. The purpose of this study was to define the limitations of asymmetrical reaming during correction of excessive glenoid retroversion during total shoulder arthroplasty. Material and methods: Five fresh cadaver shoulders were used. The size of the glenoid cavity and the humeral head were measured to select the optimal size for the glenoid implant. The scapula was embedded in resin. Posterior glenoid erosion was created by reaming to simulate wear producing retroversion greater than 15°. A control computed tomography (CT) was obtained to verify the lesion. The glenoid cavity was then prepared in the same manner as for prosthesis implantation, restoring neutral version to enable implantation of the prosthetic component of the size initially determined. A second CT was obtained to confirm the correction of the retroversion. Results: The retroversion was corrected in all cases. At least one point of the implant penetrated the glenoid wall in all cases. In three cases, four points were outside the wall. In one case, reaming caused a fracture of the anterior glenoid rim. Finally, in one case, the size of the implant had to be reduced to avoid an oversized implant. Discussion: The limitations for asymmetrical reaming to correct for posterior wear yet leave enough bone stock for implantation of a glenoid prosthesis are not defined. This study shows that asymmetrical reaming of the anterior rim of the glenoid cavity cannot satisfactorily correct for glenoid retroverson greater than 15° because of the frailness of the anterior wall and the risk the points will penetrate the rim. These complications compromise the primary stablity of the prosthesis and probably secondary short-term and mid-term stability. Conclusion: If the glenoid retroversion is excessive (> 15°), it would be advisable to graft the posterior defect

Aims. Existing literature indicates that inferiorly inclined glenoid baseplates following reverse total shoulder arthroplasty (RSA) produce better outcomes compared to superiorly inclined baseplates. We aim to compare clinical outcomes for RSAs with superiorly and neutrally/inferiorly inclined lateralized glenospheres. Methods. We retrospectively reviewed 154 consecutive patients undergoing RSA between July 2015 and July 2017 by one single-fellowship trained surgeon (AJ). Two raters (KAM and MVS) independently measured glenoid inclination in preoperative and minimum two year follow-up radiographs (anteroposterior/Grashey) using the RSA angle. Inclination was then compared to patient-reported outcomes, range of motion (ROM), and independently assessed degree of scapular notching and staging of heterotopic ossification at two year follow-up. Results. Median postoperative inclination for each group was found to be -3.6° (interquartile range (IQR) -2.1 to -6.9) and 6.0° (3.2° to 10.1°) for the neutrally/inferiorly and superiorly inclined cohorts, respectively. Preoperative inclination was highly associated with postoperative inclination (p = 0.004). When comparing superiorly and neutrally/inferiorly inclined glenospheres, there were no differences in heterotopic ossification (p = 0.606), scapular notching (p = 0.367), American Shoulder and Elbow Surgeons score (p = 0.419), Single Assessment Numeric Evaluation (p = 0.417), Visual Analogue Scale (VAS) pain score (p = 0.290), forward elevation (p = 0.161), external rotation (p = 0.537), or internal rotation (p = 0.656). Conclusion. Compared to neutral and inferior inclination, up to 6° ± 3° of superior glenoid baseplate inclination on a lateralized RSA design produces no differences in postoperative ROM or patient-reported outcomes, and produces similar levels of scapular notching and heterotopic ossification. Additionally, the degree of preoperative inclination represents an important factor in surgical decision-making as it is strongly associated with postoperative inclination. It is important to note that the findings of this study are only reflective of lateralized RSA prostheses. Cite this article: Bone Joint J 2021;103-B(2):360–365

Abstract. Aim. Excessive glenoid retroversion and posterior wear leads to technical challenges when performing anatomic shoulder replacement. Various techniques have been described to correct glenoid version, including eccentric reaming, bone graft, posterior augmentation and custom prosthesis. Clinical outcomes and survivorship of a Stemless humeral component with cemented pegged polyethylene glenoid with eccentric reaming to partially correct retroversion are presented. Patients and Methods. Between 2010– 2019, 115 Mathys Affinis Stemless Shoulder Replacements were performed. 50 patients with significant posterior wear and retroversion (Walch type B1, B2, B3 and C) were identified. Measurement of Pre-operative glenoid retroversion and Glenoid component version on a post op axillary view was performed by method as described by Matsen FA. Relative correction was correlated with clinical and radiological outcome. Results. 4 were lost to follow up. 46 patients were therefore reviewed. The mean follow up was 4 years (2–8.9 years). Walch B1, Pre op Retroversion: 12 (8–20), post op retroversion :11.8 (−4 to 19), correction= 0.2. Walch B2, Pre op Retroversion :18.4 (10–32), post op retroversion: 13.2 (1 −22), correction= 5.2. Walch B3, Pre op Retroversion: 19.1 (13–32)post op retroversion : 16.1 (9–25), correction= 3.0. Walch C, Pre op Retroversion: 33.3 (28–42) post op retroversion: 16.0 (6–27), correction= 17.3. 3 patients required revision surgery for rotator cuff failure. Conclusion. Partial correction of glenoid retroversion with eccentric reaming and implantation of cemented pegged polyethylene component leads to satisfactory clinical outcomes at midterm follow up. No revisions for aseptic loosening of the glenoid were required

This paper presents an ongoing review of the use of a wedge-shaped porous metal augments in the shoulder to address glenoid retroversion as part of anatomical total shoulder arthroplasty (aTSA). Seventy-five shoulders in 66 patients (23 women and 43 men, aged 42 to 85 years) with Walch grade B2 or C glenoids underwent porous metal glenoid augment (PMGA) insertion as part of aTSA. Patients received either a 15º or 30º PMGA wedge (secured by screws to the native glenoid) to correct excessive glenoid retroversion before a standard glenoid component was implanted using bone cement. Neither patient-specific guides nor navigation were used. Patients were prospectively assessed using shoulder functional assessments (Oxford Shoulder Score [OSS], American Shoulder and Elbow Standardized Shoulder Assessment Form [ASES], visual analogue scale [VAS] pain scores and forward elevation [FE]) preoperatively, at three, six, and 12 months, and yearly thereafter, with similar radiological surveillance. Forty-nine consecutive series shoulders had a follow-up of greater than 24 months, with a median follow-up of 48 months (range: 24–87 months). Median outcome scores improved for OSS (21 to 44), ASES (24 to 92), VAS (7 to 0), and FE (90º to 140º). Four patients died, but no others were lost to follow-up. Apart from one infection at 18 months postoperatively and one minor peg perforation, there were no complications, hardware failures, implant displacements, significant lucency or posterior re-subluxations. Radiographs showed good incorporation of the wedge augment with correction of glenoid retroversion from median 22º (13º to 46º) to 4º. All but four glenoids were corrected to within the target range (less than 10º retroversion). The porous metal wedge-shaped augments effectively addressed posterior glenoid deficiency as part of aTSA for rotator cuff intact osteoarthritis, producing satisfactory clinical outcomes with no signs of impending future failure

Ideberg-Goss type VI/AO F2(4) glenoid fossa fractures are a rare and complex injury. Although some advocate non-operative management, grossly displaced glenoid fossa fractures in the young patient may warrant fixation. Current approaches still describe difficulty with access of the entirety of the glenoid, particularly the postero-superior quadrant. We present 2 cases of Ideberg-Goss type VI/AO F2(4) glenoid fossa fractures treated with fixation through a novel “Deltoid Takedown” approach, which allows safe access to the whole glenoid with satisfactory clinical results at 5 and 7 years respectively

Aims. To report early (two-year) postoperative findings from a randomized controlled trial (RCT) investigating disease-specific quality of life (QOL), clinical, patient-reported, and radiological outcomes in patients undergoing a total shoulder arthroplasty (TSA) with a second-generation uncemented trabecular metal (TM) glenoid versus a cemented polyethylene glenoid (POLY) component. Methods. Five fellowship-trained surgeons from three centres participated. Patients aged between 18 and 79 years with a primary diagnosis of glenohumeral osteoarthritis were screened for eligibility. Patients were randomized intraoperatively to either a TM or POLY glenoid component. Study intervals were: baseline, six weeks, six-, 12-, and 24 months postoperatively. The primary outcome was the Western Ontario Osteoarthritis Shoulder QOL score. Radiological images were reviewed for metal debris. Mixed effects repeated measures analysis of variance for within and between group comparisons were performed. Results. A total of 93 patients were randomized (46 TM; 47 POLY). No significant or clinically important differences were found with patient-reported outcomes at 24-month follow-up. Regarding the glenoid components, there were no complications or revision surgeries in either group. Grade 1 metal debris was observed in three (6.5%) patients with TM glenoids at 24 months but outcomes were not negatively impacted. Conclusion. Early results from this RCT showed no differences in disease-specific QOL, radiographs, complication rates, or shoulder function between uncemented second-generation TM and cemented POLY glenoids at 24 months postoperatively. Revision surgeries and reoperations were reported in both groups, but none attributed to glenoid implant failure. At 24 months postoperatively, Grade 1 metal debris was found in 6.5% of patients with a TM glenoid but did not negatively influence patient-reported outcomes. Longer-term follow-up is needed and is underway. Cite this article: Bone Jt Open 2021;2(9):728–736

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

Summary Statement. In this study, excellent positioning of custom-made glenoid components was achieved using patient-specific guides. Achieving the preoperatively planned orientation of the component improved significantly and more screws were located inside the scapular bone compared to implantations without such guide. Introduction. Today's techniques for total or reverse shoulder arthroplasty are limited when dealing with severe glenoid defects. The available procedures, for instance the use of bone allografts in combination with available standard implants, are technically difficult and tend to give uncertain outcomes (Hill et al. 2001; Elhassan et al. 2008; Sears et al. 2012). A durable fixation between bone and implant with optimal fit and implant positioning needs to be achieved. Custom-made defect-filling glenoid components are a new treatment option for severe glenoid defects. Despite that the patient-specific implants are uniquely designed to fit the patient's bone, it can be difficult to achieve the preoperatively planned position of the component, resulting in less optimal screw fixation. We hypothesised that the use of a patient-specific guide would improve implant and screw positioning. The aim of this study was to evaluate the added value of a newly developed patient-specific guide for implant and screw positioning, by comparing glenoid implantations with and without such guide. Patients & Methods. Large glenoid defects, representative for the defects encountered in clinical practice, were created in ten cadaveric shoulders. A CT scan of each cadaver was taken to evaluate the defects and to generate three-dimensional models of the scapular bones. Based on these models, custom glenoid components were designed. Furthermore, a newly developed custom guide was designed for five randomly selected shoulders. New CT scans were taken after implantation to generate 3D models of the bone and the implanted component and screws. This enabled to compare the experimentally achieved and preoperatively planned reconstruction. The location and orientation of the glenoid component and screw positioning were determined and differences with the optimal preoperative planning were calculated. Results. An excellent component positioning (difference in location: 1.4±0, 7mm; difference in orientation: 2, 5±1, 2°) was achieved when using the guide compared to implantations without guidance (respectively 1, 7±0, 5mm; 5, 1±2, 3°). The guide improved component orientation significantly (P<0.1). After using the guide, all screws were positioned inside the scapular bone whereas 25% of the screws placed without guidance were positioned outside the scapular bone. Discussion/Conclusion. In this study, excellent positioning of custom-made glenoid components was achieved using patient-specific guides. Achieving the preoperatively planned orientation of the component improved significantly and more screws were located inside the scapular bone compared to implantations without such guide

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

This study examined the regional variations of cortical and cancellous bone density present in superiorly eroded glenoids. It is hypothesized that eroded regions will contain denser bone in response to localized stress. The shift in natural joint articulation may also cause bone resorption in areas opposite the erosion site. Clinical CT scans were obtained for 32 shoulders (10m/22f, mean age 72.9yrs, 56–88yrs) classified as having E2-type glenoid erosion. The glenoid was divided into four measurement regions - anterior, inferior, posterior, and superior - as well as five depth regions. Depth regions were segmented in two-millimeter increments from zero to 10 millimeters, beginning at the center of the glenoid surface. A repeated-measures multiple analysis of variance (RM-MANOVA) was performed using SPSS statistical software to look for differences and interactions between mean densities in each depth, quadrant, and between genders. A second RM-MANOVA was performed to examine effects of gender and quadrant on cortical to cancellous bone volume ratios. Significance was set at p < 0 .05. Quadrant and depth variables showed significant multivariate main effects (p 0.147 respectively). Quadrant, depth, and their interaction showed significant univariate main effects for cortical bone (p≤0.001) and cancellous bone (p < 0 .001). The lowest bone density was found to be in the inferior quadrant for cancellous bone (307±50 HU, p < 0 .001). The superior quadrant contained the highest mean density for cortical bone (895±97 HU), however it was only significantly different than in the posterior quadrant (865±97 HU, p=0.022). As for depth, it was found that cortical bone is most dense at the glenoid surface (zero to two millimeters, 892±91 HU) when compared to bone at two to eight millimeters in depth (p < 0 .02). Cancellous bone was also most dense at the surface (352±51 HU), but only compared to the eight to 10 millimeters depth (p=0.005). Cancellous bone density was found to decrease with increasing depth. For cortical-to-cancellous bone volume ratios, the inferior quadrant (0.37±0.28) had a significantly lower ratio than all other quadrants (p < 0 .001). The superoposterior region of the glenoid was found to have denser cancellous bone and a high ratio of cortical to cancellous bone, likely due to decreased formation of cancellous bone and increased formation of cortical bone, in response to localized stresses. The inferior quadrant was found to have the least dense cortical and cancellous bone, and the lowest volume of cortical bone relative to cancellous bone. Once again, this is likely due to reduction in microstrain responsible for bone adaptation via Wolff's law. The density values found in this study generally agree with the range of values found in previous studies of normal and arthritic glenoids. An important limitation of this study is the sizing of measurement regions. For a patient with a smaller glenoid, a depth measurement of two millimeters may represent a larger portion of the overall glenoid vault. Segments could be scaled for each patient based on a percentage of each individual's glenoid size

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

Patients receiving reverse total shoulder arthroplasty (RTSA) often have osseous erosions because of glenohumeral arthritis, leading to increased surgical complexity. Glenoid implant fixation is a primary predictor of the success of RTSA and affects micromotion at the bone-implant interface. Augmented implants which incorporate specific geometry to address superior erosion are currently available, but the clinical outcomes of these implants are still considered short-term. The objective of this study was to investigate micromotion at the glenoid-baseplate interface for a standard, 3 mm and 6 mm lateralized baseplates, half-wedge, and full-wedge baseplates. It was hypothesized that the mechanism of load distribution from the baseplate to the glenoid will differ between implants, and these varying mechanisms will affect overall baseplate micromotion. Clinical CT scans of seven shoulders (mean age 69 years, 10°-19° glenoid inclinations) that were classified as having E2-type glenoid erosions were used to generate 3D scapula models using MIMICS image processing software (Materialise, Belgium) with a 0.75 mm mesh size. Each scapula was then repeatedly virtually reconstructed with the five implant types (standard,3mm,6mm lateralized, and half/full wedge; Fig.1) positioned in neutral version and inclination with full backside contact. The reconstructed scapulae were then imported into ABAQUS (SIMULIA, U.S.) finite element software and loads were applied simulating 15°,30°,45°,60°,75°, and 90° of abduction based on published instrumented in-vivo implant data. The micromotion normal and tangential to the bone surface, and effective load transfer area were recorded for each implant and abduction angle. A repeated measures ANOVA was used to perform statistical analysis. Maximum normal micromotion was found to be significantly less when using the standard baseplate (5±4 μm), as opposed to the full-wedge (16±7 μm, p=0.004), 3 mm lateralized (10±6 μm, p=0.017), and 6 mm lateralized (16±8 μm, p=0.007) baseplates (Fig.2). The half-wedge baseplate (11±7 μm) also produced significantly less micromotion than the full-wedge (p=0.003), and the 3 mm lateralized produced less micromotion than the full wedge (p=0.026) and 6 mm lateralized (p=0.003). Similarly, maximum tangential micromotion was found to be significantly less when using the standard baseplate (7±4 μm), as opposed to the half-wedge (12±5 μm, p=0.014), 3 mm lateralized (10±5 μm, p=0.003), and 6 mm lateralized (13±6 μm, p=0.003) baseplates (Fig.2). The full wedge (11±3 μm), half-wedge, and 3 mm lateralized baseplate also produced significantly less micromotion than the 6 mm lateralized (p=0.027, p=012, p=0.02, respectively). Both normal and tangential micromotion were highest at the 30° and 45° abduction angles (Fig.2). The effective load transfer area (ELTA) was lowest for the full wedge, followed by the half wedge, 6mm, 3mm, and standard baseplates (Fig.3) and increased with abduction angle. Glenoid baseplates with reduced lateralization and flat backside geometries resulted in the best outcomes with regards to normal and tangential micromotion. However, these types of implants are not always feasible due to the required amount of bone removal, and medialization of the bone-implant interface. Future work should study the acceptable levels of bone removal for patients with E-type glenoid erosion and the corresponding best implant selections for such cases. For any figures or tables, please contact the authors directly

Aims. The aim of this study was to report the incidence of implant-related complications, further operations, and their influence on the outcome in a series of patients who underwent primary reverse total shoulder arthroplasty (RTSA). Methods. The prospectively collected clinical and radiological data of 797 patients who underwent 854 primary RTSAs between January 2005 and August 2018 were analyzed. The hypothesis was that the presence of complications would adversely affect the outcome. Further procedures were defined as all necessary operations, including reoperations without change of components, and partial or total revisions. The clinical outcome was evaluated using the absolute and relative Constant Scores (aCS, rCS), the Subjective Shoulder Value (SSV) scores, range of motion, and pain. Results. The overall surgical site complication rate was 22% (188 complications) in 152 patients (156 RTSAs; 18%) at a mean follow-up of 46 months (0 to 169). The most common complications were acromial fracture (in 44 patients, 45 RTSAs; 5.3%), glenoid loosening (in 37 patients, 37 RTSAs; 4.3%), instability (in 23 patients, 23 RTSAs; 2.7%), humeral fracture or loosening of the humeral component (in 21 patients, 21 RTSAs; 2.5%), and periprosthetic infection (in 14 patients, 14 RTSAs; 1.6%). Further surgery was undertaken in 79 patients (82 RTSAs) requiring a total of 135 procedures (41% revision rate). The most common indications for further surgery were glenoid-related complications (in 23 patients, 23 RTSAs; 2.7%), instability (in 15 patients, 15 RTSAs; 1.8%), acromial fractures (in 11 patients, 11 RTSAs; 1.3%), pain and severe scarring (in 13 patients, 13 RTSAs; 1.5%), and infection (in 8 patients, 8 RTSAs; 0.9%). Patients who had a complication had significantly worse mean rCS scores (57% (SD 24%) vs 81% (SD 16%)) and SSV scores (53% (SD 27%) vs 80% (SD 20%)) compared with those without a complication. If revision surgery was necessary, the outcome was even further compromised (mean rCS score: 51% (SD 23%) vs 63% (SD 23%); SSV score: 4% (SD 25%) vs 61% (SD 27%). Conclusion. Although the indications for, and use of, a RTSA are increasing, it remains a demanding surgical procedure. We found that about one in five patients had a complication and one in ten required further surgery. Both adversely affected the outcome. Cite this article: Bone Joint J 2022;104-B(3):401–407

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

Glenoid exposure is the name of the game in total shoulder arthroplasty. I can honestly say that it took me more than 5 years but less than 10 to feel confident exposing any glenoid, regardless of the degree of bone deformity and the severity of soft-tissue contracture. This lecture represents the synthesis of my experience exposing some of the most difficult glenoids. The basic principles are performing extensive soft-tissue release, minimizing the anteroposterior dimension of the humerus by osteophyte excision, making an accurate humeral neck cut, having a plethora of glenoid retractors, and knowing where to place them. The ten tips, in reverse order of importance are: 10.) Tilt the table away from operative side—this helps face the surface of the glenoid, especially in cases of posterior wear, toward the surgeon. 9.) Have multiple glenoid retractors—these include a large Darrach, a reverse double-pronged Bankart, one or two blunt Homans, small and large Fukudas. 8.) Remove all humeral osteophytes before attempting to retract the humerus posteriorly to expose the glenoid—this helps to decrease the overall anteroposterior dimension of the humerus and allows for maximum posterior displacement of the humerus. 7.) Make an accurate humeral neck cut—even 5mm of extra humeral bone will make glenoid exposure difficult. 6.) Optimal humeral position—it has been taught that abduction, external rotation, and extension is the optimal position. It may vary with each case. Therefore, experiment with humeral rotation to find the position that allows maximum visualization. This is often the position that makes the cut surface of the humerus parallel to the surface of the glenoid. 5.) Optimal retractor placement—my typical retractor placement is a Fukuda on the posterior lip of the glenoid, a reverse double-pronged Bankart on the anterior neck of the scapula, and a blunt Homan posterosuperiorly. Occasionally, a second blunt Homan anteroinferiorly is helpful, particularly in muscular males with a large pectoralis major. 4.) Laminar spreader for lateral humeral displacement—this can be helpful for posterior capsulorrhaphy or for posterior glenoid bone grafting. 3.) Maximal humeral capsular release—the release of the anterior capsule from the humerus must go well past the 6 o'clock position and up the posterior surface of the humerus. This aides in humeral exposure but also allows for more posterior displacement of the humerus during glenoid exposure. 2.) Anteroinferior capsular release or excision—extensive anteroinferior release or excision (my preference), allows for maximal posterior humeral displacement and also restores external rotation. 1.) Posterior or posteroinferior capsular release—release of the posteroinferior corner of the capsule from the glenoid results in a noticeable increase in posterior humeral retractability. In cases without substantial posterior subluxation, extensive release of the entire posterior capsule is performed

Aims. Patient-specific glenoid guides (PSGs) claim an improvement in accuracy and reproducibility of the positioning of components in total shoulder arthroplasty (TSA). The results have not yet been confirmed in a prospective clinical trial. Our aim was to assess whether the use of PSGs in patients with osteoarthritis of the shoulder would allow accurate and reliable implantation of the glenoid component. Patients and Methods. A total of 17 patients (three men and 14 women) with a mean age of 71 years (53 to 81) awaiting TSA were enrolled in the study. Pre- and post-operative version and inclination of the glenoid were measured on CT scans, using 3D planning automatic software. During surgery, a congruent 3D-printed PSG was applied onto the glenoid surface, thus determining the entry point and orientation of the central guide wire used for reaming the glenoid and the introduction of the component. Manual segmentation was performed on post-operative CT scans to compare the planned and the actual position of the entry point (mm) and orientation of the component (°). Results. The mean error in the accuracy of the entry point was -0.1 mm (standard deviation (. sd. ) 1.4) in the horizontal plane, and 0.8 mm (. sd. 1.3) in the vertical plane. The mean error in the orientation of the glenoid component was 3.4° (. sd. 5.1°) for version and 1.8° (. sd. 5.3°) for inclination. Conclusion. Pre-operative planning with automatic software and the use of PSGs provides accurate and reproducible positioning and orientation of the glenoid component in anatomical TSA. Cite this article: Bone Joint J 2016;98-B:1080–5

Background. Rotator cuff atrophy evaluated with computed tomography scans has been associated with asymmetric glenoid wear and humeral head subluxation in glenohumeral arthritis. Magnetic resonance imaging has increased sensitivity for identifying rotator cuff pathology and has not been used to investigate this relationship. The purpose of this study was to use MRI to assess the association of rotator cuff muscle atrophy and glenoid morphology in primary glenohumeral arthritis. Methods. 132 shoulders from 129 patients with primary GHOA were retrospectively reviewed and basic demographic information was collected. All patients had MRIs that included appropriate orthogonal imaging to assess glenoid morphology and rotator cuff pathology and were reviewed by two senior surgeons. All patients had intact rotator cuff tendons. Glenoid morphology was assigned using the modified-Walch classification system (types A1, A2, B1, B2, B3, C, and D) and rotator cuff fatty infiltration was assigned using Goutallier scores. Results. 46 (35%) of the shoulders had posterior wear patterns (23 type B2s, 23 type B3s). Both the infraspinatus and teres minor independently had significantly more fatty infiltration in B2 and B3 type glenoids compared to type A glenoids (p<0.001). There was a greater imbalance in posterior rotator cuff muscle fatty atrophy in B2 and B3 type glenoids compared to type A glenoids (p<0.001). However, there was no difference in axial plane imbalance between B2 and B3 glenoids (p=1.00). There was increased amount fatty infiltration of the infraspinatus among B2 and B3-type glenoids compared to type A glenoids on multivariate analysis controlling for age and gender (p<0.001). Conclusions. These results identify significant axial plane rotator cuff muscle imbalances in B2 and B3-type glenoids compared to concentrically worn glenoids, favoring a relative increase in fatty infiltration of the infraspinatus and teres minor compared to the subscapularis in glenoids with patterns of posterior wear. For any figures or tables, please contact authors directly

Aims. We evaluated clinical and radiographic outcomes of total shoulder arthroplasty (TSA) using the second-generation Trabecular Metal (TM) Glenoid component. The first generation component was withdrawn in 2005 after a series of failures were reported. Between 2009 and 2012, 40 consecutive patients with unilateral TSA using the second-generation component were enrolled in this clinical study. The mean age of the patients was 63.8 years (40 to 75) and the mean follow-up was 38 months (24 to 42). Methods. Patients were evaluated using the Constant score (CS), the American Shoulder and Elbow Surgeons (ASES) score and routine radiographs. Results. Significant differences were found between the pre- and post-operative CS (p = 0.003), ASES (p = 0.009) scores and CS subscores of pain (p < 0.001), strength (p < 0.001) and mobility items (p < 0.05). No glenoid or humeral components migrated. Posterior thinning of the keel and slight wear at the polyethylene-TM interface was observed in one patient but was asymptomatic. Radiolucent lines were found around three humeral (< 1.5 mm) and two glenoid components (< 1 mm) and all were asymptomatic. Discussion. TSA with the second-generation TM Glenoid component results in satisfactory to excellent clinical performance, function, and subjective satisfaction at a mean follow-up of about three years. Radiographic changes were few and did not affect the outcome. Take home message: This paper highlights that the second generation Trabecular Metal Glenoid has better outcomes than those reported with the first-generation component.  . Cite this article: Bone Joint J 2016;98-B:75–80

Aims. Patients with recurrent anterior dislocation of the shoulder commonly have an anterior osseous defect of the glenoid. Once the defect reaches a critical size, stability may be restored by bone grafting. The critical size of this defect under non-physiological loading conditions has previously been identified as 20% of the length of the glenoid. As the stability of the shoulder is load-dependent, with higher joint forces leading to a loss of stability, the aim of this study was to determine the critical size of an osseous defect that leads to further anterior instability of the shoulder under physiological loading despite a Bankart repair. Patients and Methods. Two finite element (FE) models were used to determine the risk of dislocation of the shoulder during 30 activities of daily living (ADLs) for the intact glenoid and after creating anterior osseous defects of increasing magnitudes. A Bankart repair was simulated for each size of defect, and the shoulder was tested under loading conditions that replicate in vivo forces during these ADLs. The critical size of a defect was defined as the smallest osseous defect that leads to dislocation. Results. The FE models showed a high risk of dislocation during ADLs after a Bankart repair for anterior defects corresponding to 16% of the length of the glenoid. Conclusion. This computational study suggests that bone grafting should be undertaken for an anterior osseous defect in the glenoid of more than 16% of its length rather than a solely soft-tissue procedure, in order to optimize stability by restoring the concavity of the glenoid

BACKGROUND. Stability of the glenoid component is essential to ensure successful long-term outcomes following Total shoulder arthroplasty (TSA), and may be improved through better glenoid component design. As such, this study assessed identical all-polyethylene glenoid components stability, having various fixation types, using component micromotion under simulated joint loading in an osteoarthritic patient cohort. METHODS. Five all-polyethylene glenoid component designs were compared (Keel, Central-Finned 4-Peg, Peripheral 4-Peg, Cross-Keel, and Inverted-Y). A cement mantle surrounded each fixation type, except the Central-Finned 4-Peg which was surrounded by bone. The humeral component had a non-conforming radius of curvature. Scapular models of six type A1 osteoarthritic male patients (mean: 61 years old, range: 48 to 76 years old) were assigned heterogeneous bone properties based on CT intensity. Each of the 30 scapula models were truncated and fully constrained on the medial scapular border. The bone/cement interface was fully bonded, and the fixation feature/cement interface was frictionally constrained. A ‘worst case’ load magnitude of 125% BW of a 50th percentile male was used. A purely compressive load was applied to the center of the glenoid component, followed by superior, superior-posterior, posterior, inferior-posterior, and inferior loads. Stability of the glenoid component based solely on the fixation type was determined using the mean and maximum normal (liftoff) and tangential (sliding) micromotion in six regions of the glenoid component. RESULTS. The greatest mean normal micromotion occurred for the Inverted-Y (90 ± 36 μm) in the anterior- inferior region of the component under a posterior-superior directed load. The mean normal micromotions were significantly less for the same region and loading direction in the Peripheral 4-peg (48 ± 16 μm; p < .001) and Central-Finned 4-Peg (35 ± 13 μm; p < .001), but not significantly different for the Keel (78 ± 37 μm; p = .029), or Cross-Keel (82 ± 32 μm; p = .143). The same region and loading direction produced the maximum normal micromotion in the Inverted-Y (109 ± 43 μm), which was significantly greater than the other four components (Peripheral 4-peg, 61 ± 25 μm; p < .001, Keel, 89 ± 36 μm; p < .001, Central-Finned 4-Peg, 47 ± 19 μm; p < .001, and Cross-Keel, 92 ± 37 μm; p = .002). The greatest mean tangential micromotion occurred for the Cross-Keel (100 ± 36 μm) in the posterior-superior region of the glenoid component under a posterior-superior directed load. The mean tangential micromotions for all other components were significantly less (p < .001) for the same region and loading direction (Peripheral 4-peg, 73 ± 19 μm, Keel, 73 ± 22 μm, Central-Finned 4-Peg, 73 ± 26 μm, and Inverted-Y, 83 ± 24 μm). The same region and loading direction for the maximum tangential micromotion was also in the Cross-Keel (146 ± 46 μm), which was significantly greater (p < .001) from the other four components (Peripheral 4-peg, 111 ± 21 μm, Keel, 115 ± 34 μm, Central-Finned 4-Peg, 111 ± 39 μm, and Inverted-Y, 117 ± 34 μm). DISCUSSION. This study addressed the contribution of all-polyethylene glenoid component fixation types on component stability under simulated joint loading. Pegged components were significantly more stable than keeled components. An inverse relationship between normal and tangential micromotion was observed, with the greatest sliding (tangential micromotion) occurring in the direction of the applied load, and the greatest liftoff (normal micromotion) occurring opposite the applied load. This likely occurs due to polyethylene deformation of both the fixation features and the component as a whole

Our aim was to determine the most repeatable three-dimensional measurement of glenoid orientation and to compare it between shoulders with intact and torn rotator cuffs. Our null hypothesis was that glenoid orientation in the scapulae of shoulders with a full-thickness tear of the rotator cuff was the same as that in shoulders with an intact rotator cuff. We studied 24 shoulders in cadavers, 12 with an intact rotator cuff and 12 with a full-thickness tear. Two different observers used a three-dimensional digitising system to measure glenoid orientation in the scapular plane (ie glenoid inclination) using six different techniques. Glenoid version was also measured. The overall precision of the measurements revealed an error of less than 0.6°. Intraobserver reliability (correlation coefficients of 0.990 and 0.984 for each observer) and interobserver reliability (correlation coefficient of 0.985) were highest for measurement of glenoid inclination based on the angle obtained from a line connecting the superior and inferior points of the glenoid and that connecting the most superior point of the glenoid and the most superior point on the body of the scapula. There were no differences in glenoid inclination (p = 0.34) or glenoid version (p = 0.12) in scapulae from shoulders with an intact rotator cuff and those with a full-thickness tear. Abnormal glenoid orientation was not present in shoulders with a torn rotator cuff

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

Glenoid exposure is the name of the game in total shoulder arthroplasty. I can honestly say that it took me more than 5 years but less than 10 to feel confident exposing any glenoid, regardless of the degree of bone deformity and the severity of soft-tissue contracture. This lecture represents the synthesis of my experience exposing some of the most difficult glenoids. The basic principles are performing extensive soft-tissue release, minimizing the anteroposterior dimension of the humerus by osteophyte excision, making an accurate humeral neck cut, having a plethora of glenoid retractors, and knowing where to place them. The ten tips, in reverse order of importance are: 10.) Tilt the table away from operative side—this helps face the surface of the glenoid, especially in cases of posterior wear, toward the surgeon. 9.) Have multiple glenoid retractors—these include a large Darrach, a reverse double-pronged Bankart, one or two blunt Homans, small and large Fukudas. 8.) Remove all humeral osteophytes before attempting to retract the humerus posteriorly to expose the glenoid—this helps to decrease the overall anteroposterior dimension of the humerus and allows for maximum posterior displacement of the humerus. 7.) Make an accurate humeral neck cut—even 5mm of extra humeral bone will make glenoid exposure difficult. 6.) Optimal humeral position—it has been taught that abduction, external rotation, and extension is the optimal position. It may vary with each case. Therefore, experiment with humeral rotation to find the position that allows maximum visualization. This is often the position that makes the cut surface of the humerus parallel to the surface of the glenoid. 5.) Optimal retractor placement—my typical retractor placement is a Fukuda on the posterior lip of the glenoid, a reverse double-pronged Bankart on the anterior neck of the scapula, and a blunt Homan posterosuperiorly. Occasionally, a second blunt Homan anteroinferiorly is helpful, particularly in muscular males with a large pectoralis major. 4.) Laminar spreader for lateral humeral displacement—this can be helpful for posterior capsulorrhaphy or for posterior glenoid bone grafting. 3.) Maximal humeral capsular release—the release of the anterior capsule from the humerus must go well past the 6 o'clock position and up the posterior surface of the humerus. This aides in humeral exposure but also allows for more posterior displacement of the humerus during glenoid exposure. 2.) Anteroinferior capsular release or excision—extensive anteroinferior release or excision (my preference), allows for maximal posterior humeral displacement and also restores external rotation. 1.) Posterior or posteroinferior capsular release—release of the posteroinferior corner of the capsule from the glenoid results in a noticeable increase in posterior humeral retractability. In cases without substantial posterior subluxation, extensive release of the entire posterior capsule is performed. Following these steps will help the surgeon to gain adequate glenoid exposure, even in the most difficult cases

Aims. Our aim was to investigate the outcomes of patients with a displaced fracture of the glenoid fossa who are treated conservatively. There is little information in the literature about the treatment of these rare injuries non-operatively. Patients and Methods. We reviewed 24 patients with a mean age of 52 years (19 to 81) at a mean of 5.6 years (11 months to 18 years) after the injury. Results. At final follow-up, the mean Constant and Murley score was 79 points (18 to 98); the mean Western Ontario Shoulder Instability Index score (WOSI) was 77% (12 to 100) and the mean Rowe score was 93 points (50 to 100). Fractures with little intra-articular displacement (≤ 3 mm) had an uneventful outcome. Those with intra-articular displacement of ≤ 3 mm had a significant better mean Constant and Murley score than those with displacement of ≥ 5 mm and/or a fracture gap of ≥ 5 mm. Poor clinical results such as nonunion and post-traumatic osteoarthritis were associated with displaced or angulated glenoid fragments and significant intra-articular displacement. Conclusion. Glenoid fossa fractures with displacement of ≥ 5 mm should be treated surgically if the patient’s condition allows. Displacement and angulation can lead to nonunion and a poor outcome if the degree of displacement results in a persistent fracture gap in the glenoid fossa or if the angulation of fragments leads to malunion. Cite this article: Bone Joint J 2016;98-B:1074–9

We have investigated the mid-term outcome of total shoulder replacement using a keeled cemented glenoid component and a modern cementing technique with regard to the causes of failure and loosening of the components. Between 1997 and 2003 we performed 96 total shoulder replacements on 88 patients, 24 men and 64 women with a mean age of 69.7 years (31 to 82). The minimum follow-up was five years and at the time of review 87 shoulders (77 patients) were examined at a mean follow-up of 89.1 months (60 to 127). Cumulative survival curves were generated with re-operations (accomplished and planned), survivorship of the proshesis, loosening of the glenoid (defined as tilt > 5° or subsidence > 5 mm), the presence of radiolucent lines and a Constant score of < 30 as the endpoints. There were two re-operations not involving revision of the implants and the survival rate of the prosthesis was 100.0% for the follow-up period, with an absolute Constant score of > 30 as the endpoint the survival rate was 98%. Radiological glenoid loosening was 9% after five years, and 33% after nine years. There was an incidence of 8% of radiolucent lines in more than three of six zones in the immediate post-operative period, of 37.0% after the first year which increased to 87.0% after nine years. There was no correlation between the score of Boileau and the total Constant score at the latest follow-up, but there was correlation between glenoid loosening and pain (p = 0.001). We found that total shoulder replacement had an excellent mid-term survivorship and clinical outcome. The surgical and cementing techniques were related to the decrease in radiolucent lines around the glenoid compared with earlier studies. One concern, however, was the fact that radiolucent lines increased over time and there was a rate of glenoid loosening of 9% after five years and 33% after nine years. This suggests that the design of the glenoid component, and the implantation and cementing techniques may need further improvement

Introduction. The clinical impact of radiolucent glenoid lines is controversial, where the presence of a radiolucent glenoid lines has been suggested to be an indicator of clinical glenoid loosening. The goal of this database analysis is to quantify and compare the pre- and post-operative outcomes of 427 patients who received a primary aTSA with one specific prosthesis and were sorted based upon the radiographic presence of a radiolucent glenoid line at latest clinical followup. Methods. 427 patients (mean age: 67.0yrs) with an average follow-up of 49.4 months was treated with aTSA for OA by 14 fellowship trained orthopaedic surgeons. Of these 427 patients, 293 had a cemented keel glenoids (avg follow-up = 50.8 months) and 134 had a cemented pegged glenoids (avg follow-up = 48.7 months). Cemented peg and keel glenoid patients were analyzed separately and also combined into 1 cohort: 288 patients (158 female, avg: 68.7 yrs; 130 male, avg: 64.9 yrs) did not have a radiolucent glenoid line (avg follow-up = 46.9 months); whereas, 139 patients (83 female, avg: 68.5 yrs; 56 male, avg: 64.6 yrs) had a radiolucent glenoid line (avg follow-up = 54.4 months). Outcomes were scored using SST, UCLA, ASES, Constant, and SPADI metrics; active ROM also measured. A two-tailed, unpaired t-test identified differences (p<0.05) in pre-operative, post-operative, and pre-to-post improvements. Results. The overall rate of radiolucent line formation in the glenoid for the combined peg and keel glenoid aTSA cohort was 32.6% (139 of 427 patients). The rate of radiolucent lines for the keel and peg glenoids was similar at nearly the same followup (∼50 months): 96 of 293 peg patients (32.8%) and 43 of 134 keel patients (32.1%) had a radiolucent glenoid line. Patients with cemented keeled glenoids had an average radiographic line score of 2.4 ± 1.3 which trended larger (p = 0.0875) than the average radiographic line score of 2.0 ± 1.1 of patients with cemented peg glenoids. Pre-operatively, no difference was noted between patients with and without radiolucent glenoid lines. (Figure 1) However post-operatively, patients with radiolucent glenoid lines were associated with significantly poorer clinical outcome scores according to all 5 clinical metrics and also had significantly less improvements in outcomes according to 4 of 5 outcome metrics; (Figure 2) poorer outcomes were observed for the combined cemented keeled and pegged glenoid cohorts and when each glenoid prosthesis type is analyzed separately. Additionally, patients with glenoid radiolucent lines were associated with significantly lower improvements in outcomes. (Figure 3) Finally, 24 complications were reported (5.6%), 14 for patients without radiolucent glenoid lines (4.9%) and 10 for patients with radiolucent glenoid lines (7.2%). Conclusions. This large-scale clinical outcome study demonstrated that aTSA patients with radiolucent glenoid lines were associated with significantly poorer clinical outcomes and a higher complication rate as compared to aTSA patients without radiolucent glenoid lines. The overall radiolucent line rate and the negative impact of radiolucent lines were no different between cemented keeled and cemented pegged glenoid components. Additional and longer-term follow-up is needed to confirm these conclusions. For figures/tables, please contact authors directly.

Introduction. Glenoid inclination, defined as the angle formed by the intersection of a line made of the most superior and inferior points of the glenoid and a line formed by the supraspinatus fossa, has been postulated to impact the mechanical advantage of the rotator cuff in shoulder abduction. An increase in glenoid inclination has previously been reported in patients with massive rotator cuff tears and multiple studies have correlated rotator cuff tears to an increase of the critical shoulder angle, an angle comprised of both the glenoid inclination and acromical index. Glenoid inclination is best measured by the B-angle as it has been shown to be both an accurate and reliable. The purpose of this study was to determine the correlation of glenoid inclination and the presence of degenerative rotator cuff tears. Methods. Data was prospectively collected for study patients assigned to one of two groups. The tear group consisted of patients with degenerative, atraumatic rotator cuff tears, confirmed by MRI and the control group consisted of healthy volunteers without shoulder pain. Inclusion criteria for both groups included age 45 or older. Exclusion criteria included history of previous shoulder surgery, previous patient-recalled injury to the shoulder, presence of glenoid weak, and previous humerus or glenoid fracture. Patients were also excluded from the control group if any shoulder pain or history of rotator cuff disease was present. All patients had standard anterior/posterior shoulder radiographs taken and glenoid inclination was digitally measured with Viztek OpalRad PACS software (Konica Minolta, Tokyo, Japan). The beta angle was measured to determine the glenoid inclincation. Statistical analysis was performed using SPSS version 23 (IBM, Aramonk, NY). Patient age and glenoid inclination were examined with the Shapiro-Wilk test of normality and then compared with student t tests. Gender distribution was compared with chi square test. A p-value of 0.05 was used to represent significance. Results. The study included 26 patients in the tear group and 23 patients in the control group. There was no difference in the age of the two groups (57 vs 54, p=0.292) or gender distribution (p=0.774). The average glenoid inclination was 11.18 (SD=2.67) degrees for the tear group and 5.97 (SD=2.55) degrees for the control group. This difference was statistically significant (p<0.001). Discussion. Glenoid inclination is significantly increased in patients with degenerative rotator cuff tears compared to healthy controls. Tendon overload secondary to increased glenoid inclination may be the primary anatomical factor contributing to the development of degenerative rotator cuff tears

Objectives: The aim of this study was to quantify bone microarchitecture within the glenoid fossa of the scapula. High-resolution micro-computed tomography ([mu]CT) imaging have been instrumental in providing true quantitative and qualitative three-dimensional data on baseline bone morphology. Materials and Methods: 25 fresh-frozen human cadaveric shoulders were analysed. The mean age of the specimens was 66 years. All scapulae were inspected for normal anatomic landmarks. The glenoids were cut at the glenoid neck and at the base of the coracoid process. The total, trabecular, and cortical BMDs of the 5 regions of the glenoids were determined by use of peripheral quantitative computed tomography (pQCT) (Xtrem Ct;Scanco, Zurich, Ch) Each glenoid was fixed horizontally in a custom-made jig, and axial pQCT scans (pixel size,1536/1536; slice thickness 80 microns), perpendicular to the articular surface, were obtained at the level of each area. From the resulting binarized three-dimensional reconstruction, Scanco software was used to calculate the bone volume per tissue volume; mean trabecular separation; mean trabecular number, connectivity density. Results: The total BMD of the posterior and superior glenoid were significantly higher than those of the anterior and inferior glenoid. Trabecular BMD of the posterior glenoid was significantly higher than that of the anterior glenoid, and cortical BMD of the superior glenoid was significantly higher than that of the inferior glenoid. The mean total BMD in different regions of 20 glenoid specimens ranged from 0,243 to 0,489 g/cm2. The center of the glenoid was surprisingly poor in trabecular structures as we found a bony gap at 8 mm of distance from the articular surface. Conclusions and clinical relevance: Although the specimen age was quite high in our material, we believe aging does not affect our study as shoulders prosthesis are generally performed on old patients. In the future, component design should use areas of stronger subchondral bone. Posterior and superior bone area could be another alternative for fixation in decreasing glenoid-loosening rates. As the inferior center of the glenoid is an area devoided of trabecular bone, center-keel design component doesn’t seem to be the best choice

Combined glenoid and humeral bone loss has been identified as an important factor in predicting recurrence after arthroscopic shoulder stabilisation. The “glenoid track” concept is proposed to predict recurrent instability by comparing the relative size of the glenoid to the humeral bone defect. The aim of this study was to investigate whether assessment of the glenoid track on a pre-operative MR arthrogram could be used to predict subsequent instability in a typical UK population. A retrospective study was undertaken of 175 primary arthroscopic stabilisation procedures of which 82% (n=143) were men. The median age was 26 years (IQR 22 to 32, range 16 to 77). The median follow-up was 76 months (range 21 to 125). A pre-operative MR arthrogram was used to determine if the shoulder was on-track or off-track. The endpoint of recurrent dislocation was examined. The prevalence of “off-track” bone loss in this group was 14.2% (n=25). There were 6 (24%) dislocations in the off-track group compared with 5 (3.33%) dislocations in the on-track group (RR 7.2, 95% CI 2.45 to 20.5, p=0.001). At 5 years, the cumulative redislocation rate was 26.1% in the off-track group compared with 8.7% in on-track group. The rate of any recurrent instability was 60% (n=15) v 18% (n=27) (RR 3.33, 95% CI 2.02 to 5.20, p<0.0001). Glenoid track (on v off) was not predicted by gender (p=0.411). In a typical UK population assessment of the glenoid track on an MR arthrogram can be used to risk stratify patients with shoulder instability

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

Background. Malposition of the glenoid component in total shoulder arthroplasty (TSA) is associated with higher strain patterns and can result in component loosening. Glenoid hardware placement and optimal size remain challenging due to the difficult joint exposure and visualization of anatomical reference landmarks during the procedure. Therefore, understanding both normal and variant patterns of glenoid anatomy is imperative for success in TSA. To better understand individual variations in glenoid morphology, this study aimed to compare the glenoid anatomy in a cohort of male and female patients from the United States (US) and Australia (AUS). Methods. Computed tomography (CT) data were analyzed from 41 male and 35 female shoulders; 39 of which were from a US population and 37 from an AUS population. These data were used to create statistical shape models (SSM) representing the average and ±1 standard deviations of the first mode of variation of each group (Materialise, Leuven, Belgium). All measurements were performed with 3-matic computer assisted design software (Materialise, Leuven, Belgium). On each model, glenoid height was measured as the distance from the most superior to the most inferior point on the glenoid face. Glenoid width was measured as the distance from the most anterior to the most posterior point on the glenoid face. Surface area was measured as the concave surface of the glenoid face (Figure 1). Glenoid vault depth was measured in the midsection of the glenoid face. Results. The overall glenoid dimensions were similar between AUS and US populations with average SSMs having widths of 24.68 and 25.72mm, heights of 34.63 mm and 34.85 mm, vault depths of 31.81 mm and 30.20 mm, and surface areas of 665.8 mm2 and 659.2 mm2 (Figure 2). All measurements were also similar for sex matched SSMs (Figure 3). We did observe differences between males and females within these populations, with males in general having larger glenoids in all parameters measured but the greatest difference was seen in surface area. Discussion. Our findings indicate that glenoid morphology is similar between these populations. This supports the external validity of previous studies of glenoid anatomy in these populations, and the use of similar implants between these groups. The gender differences observed in this study reflect previously reported differences. Interestingly, the glenoid depths were greater than the length of most commercial glenoid pegs (14–20 mm) or RSA screws (15–30 mm), indicating that implant perforation of the glenoid vault is unlikely if surgeons properly place and select appropriate sized glenoid implants in either population

INTRODUCTION. 3D preoperative planning software for anatomic and reverse total shoulder arthroplasty (ATSA and RTSA) provides additional insight for surgeons regarding implant selection and placement. Interestingly, the advent of such software has brought previously unconsidered questions to light on the optimal way to plan a case. In this study, a survey of shoulder specialists from the American Shoulder and Elbow Society (ASES) was conducted to examine thought patterns in current glenoid implant selection and placement. METHODS. 172 ASES members completed an 18-question survey on their thought process for how they select and place a glenoid implant for both ATSA and RTSA procedures. Data was collected using a custom online Survey Monkey survey. Surgeon answers were split into three cohorts based on their responses to usage of 3D preoperative planning software: high users, seldom users, and non-users. Data was analyzed for each cohort to examine differences in thought patterns, implant selection, and implant placement. RESULTS. 76 surgeons were grouped into the high user cohort, 66 into the seldom user cohort, and 30 into the non-user cohort. 61.9% of high users and 74.1% of seldom users performed >75 shoulder arthroplasties per year, whereas only 19.9% of non-users performed >75 arthroplasties per year (Figure 1). When questioned on glenoid implant type selection (augmented vs. non-augmented components), 80.3% of high users reported augment usage for both ATSA and RTSA, with using augments >45% of the time in 18.4% of ATSA cases and in 22.3% of RTSA cases. For seldom users, 80.3% reported augment usage in ATSA cases, and 70.3% in RTSA cases. Seldom users reported augment usage >45% of the time in 4.5% of ATSA cases and in 1.6% of RTSA cases. For non-preoperative planning users, 53.3% reported using augments in ATSA cases, and 48.3% for RTSA cases. Non-users used augmented glenoid components >45% of the time in 6.6% of ATSA cases and in 6.8% of RTSA cases. For resultant implant superior inclination in RTSA, 40.8% of high users aim for 0° of inclination, followed by 31.8% for seldom users and 16.7% of non-users (Figure 2). CONCLUSION. The results of this study show that 3D preoperative planning software has an influence on the decision making process when planning a shoulder arthroplasty. High volume shoulder arthroplasty surgeons report higher preoperative planning software usage than low volume surgeons, suggesting the utility of such software. Augmented glenoid component usage for both ATSA and RTSA is also higher for surgeons that use preoperative planning software, which either suggests the utility of augmented glenoid components, or that the use of such software creates the perceived need for augmented glenoid components. Lastly, surgeons who preoperatively plan tend to orient their glenoid components differently, which could suggest either a better understanding of the anatomy through the use of the software, or an influence on mindset regarding implant orientation resulting from software usage. This highlights an area for future work that could correlate clinical outcome data to implant selection and placement to prove what is the optimal plan for a given patient. For any figures or tables, please contact the authors directly

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

BACKGROUND. Abnormal glenoid version positioning has been recognized as a cause of glenoid component failure caused by the rocking horse phenomenon. In contrast, the importance of the glenoid inclination has not been investigated. MATERIALS AND METHODS. The computed tomography scans of 152 healthy shoulders were evaluated. A virtual glenoid component was positioned in 2 different planes: the maximum circular plane (MCP) and the inferior circle plane (ICP). The MCP was defined by the best fitting circle of the most superior point of the glenoid and 2 points at the lower glenoid rim. The ICP was defined by the best fitting circle on the rim of the inferior quadrants. The inclination of both planes was measured as the intersection with the scapular plane. We defined the force vector of the rotator force couple and calculated the magnitude of the shear force vector on a virtual glenoid component in both planes during glenohumeral abduction. RESULTS. The inclination of the component positioned in the MCP averaged 95° (range, 84°–108°) and for the ICP averaged 111° (range, 94°–126°). A significant reduction in shear forces was calculated for the glenoid component in the ICP vs the MCP: 98% reduction in 60° of abduction to 49% reduction in 90° of abduction. CONCLUSION. Shear forces are significantly higher when the glenoid component is positioned in the MCP compared with the ICP, and this is more pronounced in early abduction. Positioning the glenoid component in the inferior circle might reduce the risk of a rocking horse phenomenon. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved

Glenoid bone grafting in reverse total shoulder arthroplasty (RTSA) has emerged as an effective method of restoring bone stock in the presence of complex glenoid bone loss, yet there is limited published evidence on efficacy. The aim of this study was to conduct an analysis of clinical and radiographic outcomes associated with glenoid bone grafting in primary RTSA. Patients who underwent a primary RTSA with glenoid bone grafting were retrospectively identified from the databases of two senior shoulder surgeons. Inclusion criteria included minimum of 12 months clinical and/or radiographical follow up. Patients underwent preoperative clinical and radiographic assessment. Graft characteristics (source, type, preparation), range of movement (ROM), patient-reported outcome measures (Oxford Shoulder Scores [OSS]), and complications were recorded. Radiographic imaging was used to analyse implant stability, graft incorporation, and notching by two independent reviewers. Between 2013 and 2021, a total of 53 primary RTSA procedures (48 patients) with glenoid bone grafting were identified. Humeral head autograft was used in 51 (96%) of cases. Femoral head allograft was utilised in two cases. Depending on the morphology of glenoid bone loss, a combination of structural (corticocancellous) and non-structural (cancellous) grafts were used to restore glenoid bone stock and the joint line. All grafts were incorporated at review. The mean post-operative OSS was significantly higher than the pre-operative OSS (40 vs. 22, p < 0.001). ROM was significantly improved post-operatively. One patient is being investigated for residual activity-related shoulder pain. This patient also experienced scapular notching resulting in the fracturing of the inferior screw. One patient experienced recurrent dislocations but was not revised. Overall, at short term follow up, glenoid bone grafting was effective in addressing glenoid bone loss with excellent functional and clinical outcomes when used for complex bone loss in primary RTSA. The graft incorporation rate was high, with an associated low complication rate

Aim. We present the medium-term clinical results of a reverse total shoulder arthroplasty with a trabecular metal glenoid base plate. Patients and Methods. We reviewed 125 consecutive primary reverse total shoulder arthroplasties (RTSA) implanted in 124 patients for rotator cuff arthropathy. There were 100 women and 24 men in the study group with a mean age of 76 years (58 to 89). The mean follow-up was 32 months (24 to 60). No patient was lost to follow-up. Results. There were statistically significant improvements in the mean range of movement and Oxford Shoulder Score (p < 0.001). Kaplan-Meier survivorship at five years was 96.7% (95% confidence interval 91.5 to 98.7) with aseptic glenoid failure as the end point. . Radiologically, 63 shoulders (50.4%) showed no evidence of notching, 51 (40.8%) had grade 1 notching, ten (8.0%) had grade 2 notching and one (0.8%) had grade 4 notching. Radiolucency around the glenoid base plate was found in one patient (0.8%) and around the humeral stem in five (4.0%). In all, three RTSA (2.4%) underwent revision surgery for aseptic mechanical failure of the glenoid within 11 months of surgery due to malseating of the glenosphere. Conclusion. The clinical results of this large independent single unit series are comparable to those from previous series of RTSA reported in the literature. A trabecular metal base plate is safe and effective in the medium-term. Cite this article: Bone Joint J 2016;98-B:969–75

Introduction. Varying degrees of posterior glenoid bone loss occurs in patients with end stage osteoarthritis and can result in increased glenoid retroversion. Ultimately, the goal is to correct retroversion to restore normal biomechanics of the glenohumeral joint. The goal of this study was to identify the optimal augmented glenoid design based on finite element model analysis which will provide key insights into implant loosening mechanisms and stability. Materials and Methods. Two different augmented glenoid designs, posterior wedge and posterior step- were created as a computer model by a computer aided design software (CAD). These implants were virtually implanted to correct 20° glenoid retroversion and the different mechanical parameters were calculated including: the glenohumeral contact pressure, the cement stress, the shear stress, and relative micromotions at the bone cement interface. Results. During abduction, high strain was concentrated around the peg and posterior glenoid bone. Strain was noticeably higher in stepped design (1–2%) than the wedged design (0.4–1.2%). Stepped glenoid models sustained 30% and 70% higher stresses than those experienced by the wedged glenoid implant models at two different corrections. Distractions predicted by the stepped designs were found to be at least twice as much as those by the wedged designs. Similarly, in compression values were 1.5–8 magnitudes higher in stepped designs than those of wedged designs. The wedged design, the amount of micromotion was not affected by the size of the augment (8° and 16°). Discussion. Our study showed that the wedged design experienced less stress compared to stepped design with abduction loading. Notably, the wedged design experienced less stress as the size of the wedge increased to correct a more retroverted arthritic glenoid. The step design also had the highest amount of micromotion which ultimately points to increased failures rate and decreased performace

Total shoulder replacement is a successful procedure for degenerative or some inflammatory diseases of the shoulder. However, fixation of the glenoid seems to be the main weakness with a high rate of loosening. The results using all-polyethylene components have been better than those using metal-backed components. We describe our experience with 35 consecutive total shoulder replacements using a new metal-backed glenoid component with a mean follow-up of 75.4 months (48 to 154). Our implant differs from others because of its mechanism of fixation. It has a convex metal-backed bone interface and the main stabilising factor is a large hollow central peg. The patients were evaulated with standard radiographs and with the Constant Score, the Simple Shoulder Test and a visual analogue scale. All the scores improved and there was no loosening, no polyethylene-glenoid disassembly and no other implant-related complications. We conclude that a metal-backed glenoid component is a good option in total shoulder replacement with no worse results than of those using a cemented all-polyethylene prosthesis

Introduction. The Walch Type B2 glenoid has the hallmark features of posteroinferior glenoid erosion, retroversion, and posterior humeral head subluxation. Although our understanding of the pathoanatomy of bone loss and its evolution in Type B's has improved, the etiology remains unclear. Furthermore, the morphology of the humerus in Walch B types has not been studied. The purpose of this imaging based anthropometric study was to examine the humeral torsion in Walch Type B2 shoulders. We hypothesized that there would be a compensatory decrease in humeral retroversion in Walch B2 glenoids. Methods. Three-dimensional models of the full length humerus were generated from computed tomography data of normal cadaveric (n = 59) and Walch Type B shoulders (n = 59). An anatomical coordinate system referencing the medial and lateral epicondyles was created for each model. A simulated humeral head osteotomy plane was created and used to determine humeral version relative to the epicondylar axis and the head-neck angle. Measurements were repeated by two experienced fellowship-trained shoulder surgeons to determine inter-rater reliability. Glenoid parameters (version, inclination and 2D critical shoulder angle) and posterior humeral head subluxation were calculated in the Type B group to determine the pathologic glenohumeral relationship. Two-way ANOVAs compared group and sex within humeral version and head-neck angle, and intra-class correlation coefficients (ICCs) with a 2-way random effects model and absolute agreement were used for inter-rater reliability. Results. There were statistically significant differences in humeral version between normal and Type B shoulders (p < .001) and between males and females within the normal group (p = .043). Normal shoulders had a humeral retroversion of 36±12°, while the Walch Type B group had a humeral retroversion of 14±9° relative to the epicondylar axis. For head-neck angle, there were no significant differences between sexes (p = .854), or between normal and Type B shoulders when grouped by sex (p = .433). In the Type B group, the mean glenoid version was 22±7°, glenoid inclination was 8±6°, 2D critical shoulder angle was 30±5° and humeral head subluxation was 80±9%. Inter-rater reliability showed fair agreement between the two experienced observers for head-neck angle (ICC = .562; 95% CI: -.28 to .809) and excellent agreement for humeral version (ICC = .962;.913 to .983). Although only fair agreement was found between observers in head-neck angle ICC, the difference in mean angle was only 2°. Discussion. Although much time and effort has been spent understanding and managing Type B2 glenoids, little attention has been paid to investigating associated humeral contributions to the Type B shoulder. Our results indicate that the humeral retroversion in Type B shoulders is significantly lower than in normals. These findings have several implications, including, helping to understanding the etiology of the B2, the unknown effects of arbitrarily selecting higher version angles for the humeral component, and the unknown effects of altered version on glenohumeral joint stability, loading and implant survivorship post-arthroplasty. Our results also raise an important question, whether it is best to reconstruct Type B humeral component version to pathologic version or to non-pathologic population means

Background. Use of a baseplate with a smaller diameter in reverse shoulder arthroplasty has been recommended, especially in patients with a small glenoid or insufficient bony stock due to severe glenoid wear. However, effect of a smaller baseplate on stability of the glenoid component has not been evaluated. The purpose of this study was to determine whether a smaller baseplate (25 mm) is beneficial to the initial primary stability of the glenoid component compared to that with a baseplate of a commonly used size (29 mm) by finite element analysis. Methods. Computed tomography (CT) scans of fourteen scapulae were acquired from cadavers with no apparent deformity or degenerative change. Glenoid diameter corresponding to the diameter of the inferior circle of glenoid was measured using a caliper and classified into the small and large glenoid groups based on 25mm diameter. CT slices were used to construct 3-dimensional models with Mimics (Materialise, Leuven, Belgium). A corresponding 3D Tornier Aequalis® Reversed Shoulder prosthesis model was generated by laser scanning (Rexcan 3D Laser Scanner, Solutionix, Seoul, Korea). Glenoid components with 25mm and 28mm diameter of the baseplate were implanted into the scapular of small and large glenoid group, respectively. Finite element models were constructed using Hypermesh 11.0 (Altair Engineering, Troy, MI, USA) and a reverse engineering program (Rapidform 3D Systems, Inc., Rock Hill, SC, USA). Abaqus 6.10 (Dassault Systemes, Waltham, MA) was used to simulate 30. o. , 60. o. , and 90. o. glenohumeral abduction in the scapular plane. Single axial loads of 686N (1 BW) at angles of 30. o. , 60. o. , and 90. o. abduction were applied to the center of the glenosphere parallel to the long axis of the humeral stem. Relative micromotion at the middle and inferior thirds bone–glenoid component interface, and distribution of bone stress under the glenoid component and around the screws were analyzed. Wilcoxon's rank-sum test was used for statistical comparison and p < 0.05 was considered as a minimum level of statistical significance. Results. In small glenoid group, micromotion at the middle and inferior thirds of the glenoid-glenosphere interface at angles of 30. o. and 60. o. abduction were significantly greater in the 29mm baseplate than in the 25mm baseplate. There was no significant difference in micromotion at angle of 90. o. abduction between 25mm and 29mm baseplate. In large glenoid group, there was no statistically significant difference in micromotion between 25mm and 29mm baseplate at all angles of abduction. In small glenoid group, maximum bone stress was measured at the point of cortical engagement of the inferior screw and was statistically greater in the 29mm baseplate than in the 25mm baseplate. In large glenoid group, there was no statistically significant difference of maximum bone stress around the inferior screw between 25mm and 29mm baseplates. Conclusions. Use of a baseplate with a smaller diameter (25 mm) in reverse shoulder arthroplasty is suitable for improving the primary stability of the glenoid component, especially in small glenoid

INTRODUCTION. Reverse shoulder arthroplasty (RSA) provides an effective alternative to anatomic shoulder replacements for individuals with cuff tear arthropathy, but certain osteoarthritic glenoid deformities make it challenging to achieve sufficient long term fixation. To compensate for bone loss, increase available bone stock, and lateralize the glenohumeral joint center of rotation, bony increased offset RSA (BIO-RSA) uses a cancellous autograft for baseplate augmentation that is harvested prior to humeral head resection. The motivations for this computational study are twofold: finite element (FE) studies of BIO-RSA are absent from the literature, and guidance in the literature on screw orientations that achieve optimal fixation varies. This study computationally evaluates how screw configuration affects BIO-RSA graft micromotion relative to the implant baseplate and glenoid. METHODS. A senior shoulder specialist (GSA) selected a scapula with a Walch Type B2 deformity from patient CT scans. DICOM images were converted to a 3D model, which underwent simulated BIO-RSA with three screw configurations: 2 divergent superior & inferior locking screws with 2 convergent anterior & posterior compression screws (SILS); 2 convergent anterior & posterior locking screws and 2 superior & inferior compression screws parallel to the baseplate central peg (APLS); and 2 divergent superior & inferior locking screws and 2 divergent anterior & posterior compression screws (AD). The scapula was assigned heterogeneous bone material properties based on the DICOM images’ Hounsfield unit (HU) values, and other components were assigned homogenous properties. Models were then imported into an FE program for analysis. Anterior-posterior and superior-inferior point loads and a lateral-medial distributed load simulated physiologic loading. Micromotion data between the RSA baseplate and bone graft as well as between the bone graft and glenoid were sub-divided into four quadrants. RESULTS. In all but 1 quadrant, APLS performed the worst with the graft having an average micromotion of 347.1µm & 355.9 µm relative to the glenoid and baseplate, respectively. The SILS configuration ranked second, having 211.2 µm & 274.4 µm relative to the glenoid and baseplate. AD performed best, allowing 247.4 µm & 225.4 µm of graft micromotion relative to the glenoid and baseplate. DISCUSSION. Both APLS and SILS techniques are described in the literature for BIO-RSA fixation; however, the data indicate that AD is superior in its ability to reduce graft micromotion, and thus some revision to common practices may be necessary. While these micromotion data are larger than data in the extant RSA literature, there are several factors that account for this. First, to properly model the difference between locking and compression screws, we simulated friction between the compression screw heads and baseplate rather than a tied constraint as done in other studies, resulting in larger micromotion. Second, the trabecular bone graft is at greater risk of deforming than metallic spacers used when studying micromotion with glenosphere lateralization, increasing graft deflection magnitude. Future work will investigate the effects of various BIO-RSA variables. For any figures or tables, please contact authors directly

Introduction. Varying degrees of posterior glenoid bone loss occurs in patients with end stage osteoarthritis and can result in increased glenoid retroversion. The excessive retroversion can affect implant stability, eccentric glenoid loading, and fixation stresses. Ultimately, the goal is to correct retroversion to restore normal biomechanics of the glenohumeral joint. The objective of this study was to identify the optimal augmented glenoid design based on finite element analysis (FEA) modeling which will provide key insights into implant loosening mechanisms and stability. Materials and Methods. Two different augmented glenoid designs, posterior wedge and posterior step- were created as a computer model by a computer aided design software (CAD). These implant CAD models were created per precise manufacturers dimensions and sizes of the augmented implant designs. These implants were virtually implanted to correct 20° glenoid retroversion and the different mechanical parameters were calculated including: the glenohumeral subluxation force, relative micromotion at the bone-cement interface the glenoid, implant and cement mantle stress levels. The FEA model was then utilized to make measurements while the simulating abduction with the different implant designs. The biomechanical response parameters were compared between the models at comparable retroversion correction. Results. The model prediction of force ratio for the augmented wedge design was 0.56 and for the augmented step design was 0.87. The step design had higher force ratio than the wedge one at similar conformity settings. Micromotion was defined as a combination of three components based on different directions. The distraction measured for the wedge design was 0.05 mm and for the step component, 0.14 mm. Both implants showed a similar pattern translation wise. The greatest difference between the two implants was from the compression standpoint, where the step component showed almost three times more movement than the wedge design implant. Overall, the step design registered greater micromotion than the wedge one during abduction physiologic loading. The level of stress generated during abduction on the glenoid vault was 1.65 MPa for the wedge design and 3.78 MPa for the step one. All stress levels were found below the determined bone failure limit for the bone and polyethylene (10–20 MPa). Concerning implant stress, the results measured on the backside of the wedge and step components were 6.62 MPa and 13.25 MPa, respectively. Both components showed high level of stress level measured on the cement mantle, which exceeded the endurance limit for cement fracture (4 MPa). Discussion. The augmented glenoid is a novel surgical implant for use in with severe glenohumeral osteoarthritis. Unlike standard glenoid prosthetics, the augmented glenoid is better suited for correcting moderate to severe retroversion. Whereas a step design might provide higher glenohumeral stability, the tradeoff is higher glenoid vault, implant and cement mantle stress levels, and micromotion, indicating higher risks of implant loosening, failure or fracture over time, leading to poorer clinical outcomes and higher revision rates

Accurate glenoid component placement continues to be a challenge. Knowledge that glenoid loosening is affected by malpositioning of the glenoid component has led to the development of patient specific instrumentation (PSI) in an attempt to optimise glenoid positioning. The ideal PSI would be reusable, reliable, cost-effective and robust enough to tolerate the stresses applied by the surgeon in the context of difficult glenohumeral exposure. The VIP system is a CT scan-based PSI with a reusable instrument. The subtle nuances of pre-operative planning will be discussed in a separate short video. The live surgery will incorporate use of the patient specific instrumentation during glenoid placement and the use of a short stemmed fourth generation total shoulder arthroplasty

The purpose of this study is to report the clinical and radiological outcomes of patients undergoing primary or revision reverse total shoulder arthroplasty using custom 3D printed components to manage severe glenoid bone loss with a minimum of 2-year follow-up. After ethical approval (reference: 17/YH/0318), patients were identified and invited to participate in this observational study. Inclusion criteria included: 1) severe glenoid bone loss necessitating the need for custom implants; 2) patients with definitive glenoid and humeral components implanted more than 2 years prior; 3) ability to comply with patient reported outcome questionnaires. After seeking consent, included patients underwent clinical assessment utilising the Oxford Shoulder Score (OSS), Constant-Murley score, American Shoulder and Elbow Society Score (ASES), and quick Disabilities of the Arm, Shoulder, and Hand Score (quickDASH). Radiographic assessment included AP and axial projections. Patients were invited to attend a CT scan to confirm osseointegration. Statistical analysis utilised included descriptive statistics (mean and standard deviation) and paired t test for parametric data. 3 patients had revision surgery prior to the 2-year follow-up. Of these, 2/3 retained their custom glenoid components. 4 patients declined to participate. 5 patients were deceased at the time of commencement of the study. 21 patients were included in this analysis. The mean follow-up was 36.1 months from surgery (range 22–60.2 months). OSS improved from a mean 16 (SD 9.1) to 36 (SD 11.5) (p < 0.001). Constant-Murley score improved from mean 9 (SD 9.2) to 50 (SD 16.4) (p < 0.001). QuickDASH improved from mean 67 (SD 24) to 26 (SD 27.2) (p = 0.004). ASES improved from mean 28 (SD 24.8) to 70 (SD 23.9) (p = 0.007). Radiographic evaluation demonstrated good osseointegration in all 21 included patients. The utility of custom 3D-printed components for managing severe glenoid bone loss in primary and revision reverse total shoulder arthroplasty yields significant clinical improvements in this complex patient cohort

Background. Accurate placement of the glenoid component in total shoulder arthroplasty (TSA) is critical to optimize implant longevity. Commercially available patient-specific instrumentation systems can improve implant placement, but may involve considerable expense and production delays of up to six weeks. The purpose of this study was to develop a novel technique for in-house production of 3D-printed, patient-specific glenoid guides, and compare the accuracy of glenoid guidepin placement between the patient-specific guide and a standard guide using a cadaveric model. Methods. Twenty cadaveric shoulder specimens were randomized to receive glenoid guidepin placement via standard TSA guide (Wright Medical, Memphis, TN) or patient-specific guide. Three-dimensional scapular models were reconstructed from CT scans with Mimics 20.0 imaging software (Materialise NV, Leuven, Belgium). A pre-surgical plan was created for all specimens for the central glenoid guidepin of 0º version and inclination angles. Central pin entry and exit points were also calculated. Patient-specific guides were constructed to achieve the planned pin trajectory in Rhino3D software (Robert McNeel & Associates, Seattle, WA). Guides were 3D-printed on a Form2 printer with Formlabs Dental SG Resin (Formlabs, Somerville, MA). Glenoid labrum and cartilage were removed with preservation of other soft tissues in all specimens to mimic intraoperative TSA conditions. A fellowship-trained, board-eligible orthopaedic surgeon placed a 2.5 mm diameter titanium guidepin into each glenoid using the assigned guide for each specimen. After pin placement, repeat CT scans were performed, and a blinded measurer used superimposed 3D scapular reconstructions to calculate deviation from the pre-surgical plan in version and inclination angles, dot product angle, and guide pin entry and exit points. Student's t tests were performed to detect differences between pin placements for the two groups. Results. Cadaver age, sex, and BMI did not differ between groups (p>0.05 for all). Average production cost and time for the patient-specific guides were $29.95 and 4 hours and 40 minutes per guide, respectively. Guidepin version deviation did not differ between the patient-specific and standard guides (1.59º ± 1.60º versus 2.88 º ± 2.11º, respectively, p=0.141). Guidepin inclination deviation was significantly lower in the patient-specific group (1.54º ± 1.58º versus 6.42º ± 5.03º, p=0.009), similarly the dot product angle was lower in the patient-specific compared to standard guide group (2.35º ± 1.66º versus 7.48º ± 4.76º, p=0.005). Glenoid entry site exhibited less deviation for the patient-specific compared to standard guide (0.75mm ± 0.54mm versus 2.05mm ± 1.19mm, p=0.006). Glenoid exit site also was closer to the target for the patient- specific compared to standard group (1.75mm ± 0.99mm versus 4.75mm ± 2.97mm, p=0.010). Conclusion. We present a novel technique for in-house production of 3D-printed, patient-specific glenoid guides for TSA glenoid pin placement. These patient-specific guides improved pin placement accuracy based on 3D-CT measurements compared to standard TSA guides in a cadaveric model. Our patient-specific glenoid guides can be produced on-demand, in-house, inexpensively, and with significantly reduced time compared to commercially available guides. Future studies are required to validate these findings in clinical applications and determine the potential impact on implant longevity

Background. Massive rotator cuff tears and consequent cuff-deficient arthritis (CTA) of the shoulder can cause severe shoulder dysfunction in the elderly. Reverse total shoulder arthroplasty (RTSA) has been widely used for treatment of CTA in all over the world since its introduction in the 90's. In Japan, however, we have just started to clinically use RTSA from April 2014. In addition, we have only one choice of the implants (Aequalis Reverse, Tornier) currently, and only one size of the base-plate of the glenoid component (29 mm in diameter) is available so far. Japanese, especially elderly people, have generally smaller figure than Caucasians. We are not sure whether the base-plate would fit for the smaller Japanese. The purpose of this study was to measure the size of the glenoids in Japanese using CT images and to examine that they would fit the 29 mm base-plate. Methods. The shoulders without osteoarthritis of the glenohumeral joint were eligible for the study. The subjects consisted of 30 shoulders including 10 elderly males, 10 elderly females, and 10 younger males, and the mean ages were 73 (range, 63–81), 74 (range, 65–89), and 32 (range, 27–36) years old, respectively. Mean heights and weights were 164 cm (range, 156–179) and 59 kg (range, 49–72), 154 cm (range, 151–161) and 57 kg (range, 48–65), and 173 cm (range, 162–179) and 72 kg (range, 61–100), respectively. CT images with a 0.3 mm slice pitch were used for the analysis. The images were loaded into a DICOM viewer (OsiriX), and a slice for simulated implantation of the base-plate was created using the multi-planar reconstruction (Figure 1), which had 10° of inferior tilt to the glenoid face. The width of the glenoid in the antero-posterior direction was measured at 14 mm above the inferior edge of the glenoid. Results. Mean widths for the elderly males, elderly females, and younger males were 27.7 mm (range, 24.8–28.9), 25.3 mm (range, 24.4–25.9), and 27.8 mm (range, 25.9–29.8), respectively. Discussion. The present study revealed that most of the younger and elderly males would fit the 29 mm base-plate. However, the glenoid width of all elderly females in this study was much smaller than the base-plate diameter. The base-plate with smaller diameter is indispensable for Japanese, and the pre-operative planning may be important for secure surgeries

INTRODUCTION. 3D preoperative planning software for anatomic total shoulder arthroplasty (ATSA) provides surgeons with increased ability to visualize complex joint relationships and deformities. Interestingly, the advent of such software has seemed to create less of a consensus on the optimal way to plan an ATSA rather than more. In this study, a survey of shoulder specialists from the American Shoulder and Elbow Society (ASES) was conducted to examine thought patterns in current ATSA implant selection and placement. METHODS. 172 ASES members completed an 18-question survey on their thought process for how they select and place an ATSA glenoid implant. Data was collected using a custom online Survey Monkey survey. Surgeon answers were split into two cohorts based on number of arthroplasties performed per year: between 0–75 was considered low volume (LV), and between 75–200+ was considered high volume (HV). Data was analyzed for each cohort to examine differences in thought patterns, implant selection, and implant placement. RESULTS. 70 surgeons were grouped into the LV cohort, and 102 surgeons were grouped into the HV cohort. 46.1% of surgeons in the HV cohort reported using a preoperative planning software for the majority of cases vs. 41.4% in the LV cohort, 48% of surgeons in the HV cohort reported seldom use vs. 24.3% in the LV cohort, and 5.9% of surgeons in the HV cohort reported no use vs. 34.3% in the LV cohort (Figure 1). When questioned on what percentage of ATSA cases do surgeons use augmented glenoid implants, 20.6% in the HV cohort responded never using augments vs. 30% in the LV cohort, 39.2% responded using augments <15% of the time in the HV cohort vs. 34.3% in the LV cohort, 26.5% responded using augments between 15–45% of the time in the HV cohort vs. 28.6% in the LV cohort, and 13.7% responded using augments >45% of the time in the HV cohort vs. 7.2% in the LV cohort (Figure 2). When asked what the maximum allowable residual retroversion for an ATSA glenoid implant is, surgeons answered 0–5° 6.9% of the time in the HV cohort vs. 4.3% in the LV cohort, 6–9° 35.6% of the time in the HV cohort vs. 50% in the LV cohort, 10–12° 34.7% of the time in the HV cohort vs. 32.9% in the LV cohort, 13–15° 10.9% of the time in the HV cohort vs. 8.6% in the LV cohort, and lastly >16° 11.9% of the time in the HV cohort vs. 4.3% in the LV cohort (Figure 3). CONCLUSION. Research suggests ATSA glenoid implants may be less forgiving of malalignment than reverse shoulder glenoid implants, but the contrasting survey results in this study reveal that a consensus in optimal placement has yet to be reached. Interestingly, even though HV use more augmented glenoid components than LV surgeons, HV surgeons are more accepting of residual glenoid component retroversion than LV surgeons. Despite these differences, there is no way to prove the optimal implant selection and placement without long-term clinical outcomes. For any figures or tables, please contact the authors directly

Introduction. Posterior glenoid wear is common in glenohumeral osteoarthritis. Tightening of the subscapularis causes posterior humeral head subluxation and a posterior load concentration on the glenoid. The reduced contact area causes glenoid wear and potentially posterior instability. To correct posterior wear and restore glenoid version, surgeons may eccentrically ream the anterior glenoid to re-center the humeral head. However, eccentric reaming undermines prosthesis support by removing unworn anterior glenoid bone, compromises cement fixation by increasing the likelihood of peg perforation, and medializes the joint line which has implications on joint stability. To conserve bone and preserve the joint line when correcting glenoid version, manufacturers have developed posterior augment glenoids. This study quantifies the change in rotator cuff muscle length (relative to a nonworn/normal shoulder) resulting from three sizes of posterior glenoid defects using 2 different glenoids/reaming methods: 1) eccentric reaming using a standard (nonaugmented) glenoid and 2) off-axis reaming using an 8, 12, and 16° posterior augment glenoid. Methods. A 3-D computer model was developed in Unigraphics (Siemens, Inc) to simulate internal/external rotation and quantify rotator cuff muscle length when correcting glenoid version in three sizes of posterior glenoid defects using posterior augmented and non-augmented glenoid implants. Each glenoid was implanted in a 3-D digitized scapula and humerus (Pacific Research, Inc); 3 sizes (small, medium, and large) of posterior glenoid defects were created in the scapula by posteriorly shifting the humeral head and medially translating the humeral head into the scapula in 1.5 mm increments. Five muscles were simulated as three lines from origin to insertion except for the subscapularis which was wrapped. After simulated implantation in each size glenoid defect, the humerus was internally/externally rotated from 0 to 40° with the humerus at the side. Muscle lengths were measured as the average length of the three lines simulating each muscle at each degree of rotation and compared to that at the corresponding arm position for the normal shoulder without defect to quantify the percentage change in muscle length for each configuration. Results. As depicted in Figures 1–3, muscle shortening was observed for each muscle for each size defect. For each size uncorrected defect, the subscapularis was observed to wrap around the anterior glenoid rim during internal rotation and with the arm at neutral; both eccentric successfully re-centered the humeral head and eliminate subscapularis wrapping around the anterior glenoid rim. However, eccentric reaming was also found to medialize the joint line and resulted in approximately 1.5, 2.5, and 3.5% additional muscle shortening for each muscle relative to the augmented glenoid in each size defect, respectively. Discussion and Conclusions. This study demonstrates that posterior glenoid wear medializes the joint line and results in rotator cuff muscle shortening. Augmented glenoids offer the potential to better restore the joint line and minimize muscle shortening, particularly when used in large glenoid defects. Future work should investigate the clinical significance of 1.5–3.5% of muscle shortening and evaluate the functional impact of subscapularis wrapping around the anterior glenoid rim

We report the long-term clinical and radiological outcomes of the Aequalis total shoulder replacement with a cemented all-polyethylene flat-back keeled glenoid component implanted for primary osteoarthritis between 1991 and 2003 in nine European centres. A total of 226 shoulders in 210 patients were retrospectively reviewed at a mean of 122.7 months (61 to 219) or at revision. Clinical outcome was assessed using the Constant score, patient satisfaction score and range of movement. Kaplan-Meier survivorship analysis was performed with glenoid revision for loosening and radiological glenoid loosening (. sd. ) as endpoints. The Constant score was found to improve from a mean of 26.8 (. sd. 10.3) pre-operatively to 57.6 (. sd. 20.0) post-operatively (p < 0.001). Active forward flexion improved from a mean of 85.3° (. sd. 27.4) pre-operatively to 125° (. sd. 37.3) postoperatively (p < 0.001). External rotation improved from a mean of 7° (. sd. 6.5) pre-operatively to 30.3° (. sd. 21.8°) post-operatively (p < 0.001). Survivorship with revision of the glenoid component as the endpoint was 99.1% at five years, 94.5% at ten years and 79.4% at 15 years. Survivorship with radiological loosening as the endpoint was 99.1% at five years, 80.3% at ten years and 33.6% at 15 years. Younger patient age and the curettage technique for glenoid preparation correlated with loosening. The rate of glenoid revision and radiological loosening increased with duration of follow-up, but not until a follow-up of five years. Therefore, we recommend that future studies reporting radiological outcomes of new glenoid designs should report follow-up of at least five to ten years

Introduction. Posterior glenoid wear is common with glenohumeral osteoarthritis. To correct posterior wear, surgeons may eccentrically ream the anterior glenoid to restore version. However, eccentric reaming undermines prosthesis support by removing unworn anterior glenoid bone, compromises cement fixation by increasing the likelihood of peg perforation, and medializes the joint line which has implications on joint stability. To conserve bone and preserve the joint line when correcting glenoid version, manufacturers have developed posterior augment glenoids for aTSA and rTSA applications. This clinical study quantifies outcomes achieved using posteriorly augmented aTSA/rTSA glenoid implants in patients with severe posterior glenoid wear at 2 years minimum follow-up. Methods. 47 patients (mean age: 68.7yrs) with 2 years minimum follow-up were treated by 5 fellowship trained orthopaedic surgeons using either 8° posteriorly augmented aTSA/rTSA glenoid components in patients with severe posterior glenoid wear. 24 aTSA patients received posteriorly augmented glenoids (65.8 yrs; 7F/17M) for OA and 23 rTSA patients received posteriorly augmented glenoids (71.8 yrs; 9F/14M) for treatment of CTA and OA. Outcomes were scored using SST, UCLA, ASES, Constant, and SPADI metrics; active abduction, forward flexion, and external rotation were also measured to quantify function. Average follow-up was 27.5 months (aTSA 29.4; rTSA 25.5). A two-tailed, unpaired t-test identified differences (p<0.05) in pre-operative, post-operative, and pre-to-post improvements. Results. A comparison of pre-operative, post-operative, and pre-to-post improvement in outcomes are presented in Tables 1–3, respectively. As described in Table 1, pre-operative outcomes were similar for patients receiving posterior augment aTSA and posterior augment rTSA implants, with only active abduction being significantly less in rTSA patients. Additionally, rTSA patients were noted to be significantly older (p=0.0434) and have significantly longer follow-up (p=0.0358) though no difference was noted in mean patient height, weight, or BMI between cohorts. As described in Table 2, at 2 years minimum follow-up posterior augment aTSA patients were associated with significantly greater SST scores and also had significantly more active abduction and active external rotation than posterior augment rTSA patients. However, as described in Table 3, no significant difference was observed in pre-to-post improvement of outcome scoring metrics and only improvement in active external rotation was observed to be significantly different between the two cohorts. No complications were reported for either posterior augment implant cohort. Conclusions. These results demonstrate positive outcomes can be achieved at 2 years minimum follow-up in patients with severe posterior wear using either posteriorly augmented aTSA/rTSA glenoid implants. While relative differences in outcomes were noted, these mean differences are expected due to differing indications and associated differences in rotator cuff status. Due to the aforementioned concerns of aseptic glenoid loosening in patients with severe posterior glenoid wear, some have recommend treating patients with posterior glenoid wear using only rTSA regardless of the status of the patient's rotator cuff. The results of this study demonstrate that patients with posterior glenoid wear and a functioning rotator cuff can be successfully treated with posterior augmented aTSA as well. Additional and longer-term follow-up is needed to confirm these positive outcomes

Common post-operative problems in shoulder arthroplasty such as glenoid loosening and joint instability can be reduced by improvements in glenoid design shape, material choice and fixation method [1]. Innovation in shoulder replacement is usually carried out by introducing incremental changes to functioning implants [2], possibly overlooking other successful design combinations. We propose an automated framework for parametric analysis of implant design in order to efficiently assess different possible glenoid configurations. Parametric variations of reference geometries of a glenoid implant were automatically generated in SolidWorks. The different implants were aligned and implanted with repeatability using Rhino. The glenoid-bone models were meshed in Abaqus, and boundary conditions and loading applied via a custom-made Python script. Finally, another MATLAB script integrated and automated the different steps, extracted and analysed the results. This study compared the influence of reference shape (keel vs. 2-pegged) and material on the von Mises stresses and tensile and compressive strains of glenoid components with bearing surface thickness and fixation feature width of 3, 4, 5 or 6 mm. A total of 96 different glenoid geometries were implanted into a bone cube (E = 300 MPa, ν = 0.3). Fixed boundary conditions were applied at the distal surface of the cube and a contact force of 1000 N was distributed between the central nodes on the bearing surface. The implants were assigned UHMWPE (E = 1 GPa, ν = 0.46), Vitamin E PE (E = 800 MPa, ν = 0.46), CFR-PEEK (E = 18 GPa, ν = 0.41) or PCU (E = 2 GPa, ν = 0.38) material properties and the bone-implant surface was tied (Figure 1). The von Mises stresses, compressive and tensile strains for the different models were extracted. The influence of design parameters in the mechanical environment of the implant could be assessed. In this particular example, the 95. th. percentile values of the tensile and compressive strains induced by modifications in reference shape could be evaluated for all the different geometries simultaneously in form of radar plots. 2-pegged geometries (green) consistently produced lower tensile and compressive strains than the keeled (blue) configurations (Figure 2). Vitamin E PE and PCU glenoids also produced lower maximum von Mises stresses values than CFR-PEEK and UHMWPE designs (Figure 3). The developed method allows for simple, direct, rapid and repeatable comparison of different design features, material choices or fixation methods by analysing how they influence the mechanical environment of the bone surrounding the implant. Such tool can provide invaluable insight in implant design optimisation by screening through multiple potential design modifications at an early design evaluation stage and highlighting the best performing combinations. Future work will introduce physiological bone geometries and loading, a wider variety of reference geometries and fixation features, and look at bone/interface strength and osteointegration predictions

Anatomic and accurate placement of components is a primary goal in all arthroplasty procedures. Unique to total shoulder arthroplasty, challenging glenoid exposure and osteoarthritic glenoid deformity offer significant challenges and impediments to this goal. Despite thorough pre-operative planning strategies and contemporary cannulated pin-based shoulder systems, it is often times still difficult to accurately aim the guide pin to the medial border of the scapula when the deformity is substantial or exposure is difficult. Even small errors in guide pin position can result in problems with final component version, inclination and glenoid vault perforation. In addition, a malpositioned glenoid component has been shown to have a negative impact on implant longevity and clinical performance. Image-based patient specific instrumentation has been available in the lower extremity for nearly a decade with reliable results. The application of similar technology in the shoulder has demonstrated reliable positioning of the guide pin to a pre-operative plan with subsequent accurate placement of the glenoid component. This surgical demonstration will feature one of the currently available CT-based patient specific glenoid guides using a standard deltopectoral approach

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

Experience has demonstrated in the hip and knee, related to total joint replacement arthroplasty, polymethyl methacrylate cement fixation can provide problems in terms of loosening, fragmentation, particulate wear and ultimate failure. These same problems have been recognised in total shoulder arthroplasty related to cement fixation of the glenoid. While cement fixation of the humeral component has proven much less problematic, there has been a swelling towards avoidance of using cement to secure the humeral component for fear of difficulty if revision is required. Surprisingly, with the high incidence of lucent lines, bone resorption and frank loosening, representing the most common source of failure in total shoulder arthroplasty, cementless fixation of the glenoid has not been, until now, embraced. The advent of reverse total shoulder arthroplasty has demonstrated the ability for secure cementless fixation to provide long-lasting secure implant retention in implants which have inherently higher shear and stress forces passing through the implant/bone interface. In anatomic total shoulder arthroplasty a woven tantalum anchor (Trabecular Metal) has proven to demonstrate secure cementless fixation as well. This presentation will discuss the use of trabecular metal anchored glenoid implants with and without additional screw fixation for anatomic and convertible reverse arthroplasty baseplates. Avoidance of complications with successful long-lasting outcomes requires meticulous surgical attention to detail

Cement fixation of the glenoid implants in total shoulder arthroplasty has been the norm since the procedure has existed. Yet, an unacceptably high rate of lucent lines, representing prosthetic loosening, and a high rate of resultant failure of fixation of these implants continues to be the single most common cause for revision surgery in total shoulder arthroplasty. Dissatisfaction with a higher than acceptable rate of lucent lines, cement fixation of the glenoid component has led us to evaluate and employ an implant anchored into the glenoid vault with a woven tantalum (trabecular metal) fixation stem. We have employed this implant in patients with healthy bone stock with a minimum 2-year follow-up in well over 100 cases with only one revision performed in a first generation implant due to fatigue fracture. No cases have demonstrated lucency or loosening. The procedure does require meticulous attention to detail to ensure precise surface and glenoid vault preparation providing complete intraosseous seating of the trabecular metal anchor and flush apposition and support of the polyethylene surface upon the face of the glenoid. This process has reduced surgical preparation time as well as time required for cement setting by an average of 20 minutes per case

Background. Virtual planning of shoulder arthroplasty has gained recent popularity. Combined with patients specific instrumentation, several systems have been developed that allow the surgeon to accurately appreciate and correct glenoid deformities in version and inclination. While each virtual software platform utilizes a consistent algorithm for calculating these measurements, it is imperative for the surgeon to recognize any differences that may exist amongst software platforms and characterize any variability. Methods. A case-control study of all CT scans of patients previously pre-operatively planned using MatchPoint SurgiCase® software were uploaded into the BluePrint software. The cohort represents surgical planning for total shoulder arthroplasty and reverse shoulder arthroplasty with varying degrees of glenoid deformity. Glenoid version and inclination will be recorded for each CT scan using both software platforms. Results. A total of 38 patient CT scans previously planned using MatchPoint Surgicase® software were uploaded into the BluePrint software. The mean difference for glenoid version between the two software programs was 2.497° (±1.724°) with no significant differences in measured glenoid version readings between BluePrint and SurgiCase software (p=0.8127). No significant differences were seen in the measured glenoid inclination between the two software programs (p=0.733), with a mean difference for glenoid inclination between the two software programs at 5.150° ± 3.733° (figure 1). A Bland-Altman plot determined the 95% limits of agreement between the two programs at −5.879 to 6.116 degrees of glenoid version and −12.05 to 12.75 degrees of glenoid inclination. There was a significant statistical agreement between the two software programs measuring glenoid version and inclination in relation to glenoid wear position for the centered (p=0.004), posterior (p<0.001, p=0.003), posterior-superior (p<0.001, p<0.001), and superior (p=0.027, p=0.034) positions, respectively. Conclusions. Both BluePrint and SurgiCase software platforms yield similar measurements for glenoid version and glenoid inclination. In the setting of glenoid wear in the posterior, posterior-superior or superior position, measurements of between two surgical platforms are in agreement

The composition and morphology of the glenoid are integral to the support of a glenoid component in total shoulder arthroplasty (TSA). This study was performed to identify the morphology of glenoid cavity in pre and post replacements in a cadaveric model. Eleven normal cadaveric shoulders (Right – 5, Left – 6) were dissected down to the bone such that the glenoid labrum was left intact. Computerised Tomography (CT) scanning at 0.5 mm thickness was performed on each of the specimens in a standardised fashion to evaluate the morphology of the glenoid and glenoid medullary cavity. CT scanning was repeated after a mixture of cemented pegged and keeled glenoid components were inserted into all the specimens using standard instrumentation. Five reproducible lengths (Body width), Posterior wall length, Anterior Wall length. Glenoid body length and corrected body width) and the retroversion angle of the glenoid were identified on the CT scans. These measurements were taken at the 25th, 50th and 75th percentiles of the height of each glenoid both pre and post replacements. Further post glenoid replacement CT scans were analysed for cement-fill of the glenoid cavity and cortical encroachment of the prosthesis. There was significant correlation of all the measurements including the retroversion angle between the pre and post glenoid replacements at all levels. All but one pegged prosthesis had insufficient cement mantle or critical penetration or abutment at one of the pegs at least. Most often the penetration or cortical abutment was along the posterior wall. All keeled prosthesis had a sufficient cement mantle all around. The designs of the glenoid prosthesis were satisfactory with some respects like radius of curvature, size and to a certain degree the shape. The margin of error for insertion of the pegged prosthesis was very narrow. Design changes are required in the glenoid component for better bony fixation

In a prospective study between 2000 and 2005, 22 patients with primary osteoarthritis of the shoulder had a total shoulder arthroplasty with a standard five-pegged glenoid component, 12 with non-offset humeral head and ten with offset humeral head components. Over a period of 24 months the relative movement of the glenoid component with respect to the scapula was measured using radiostereometric analysis. Nine glenoids needed reaming for erosion. There was a significant increase in rotation about all three axes with time (p < 0.001), the largest occurring about the longitudinal axis (anteversion-retroversion), with mean values of 3.8° and 1.9° for the non-offset and offset humeral head eroded subgroups, respectively. There was also a significant difference in rotation about the anteversion-retroversion axis (p = 0.01) and the varus-valgus (p < 0.001) z-axis between the two groups. The offset humeral head group reached a plateau at early follow-up with rotation about the z-axis, whereas the mean of the non-offset humeral head group at 24 months was three times greater than that of the offset group accounting for the highly significant difference between them

Purpose:. The optimal degree of conformity between the glenoid and humeral components in cemented total shoulder arthroplasty (TSA) has not been established. Glenoid component stability is thought to be at risk due to the “rocking-horse” phenomenom, which, can lead to increased micromotion and loosening in response to humeral head edge loading. The goal of this biomechanical study is to investigate the influence of glenohumeral mismatch on bone-implant interface micromotion in a cemented glenoid implant model. Methods:. Twenty-Five cemented glenoid components (Affiniti, Tornier, Inc., Bloomington, MN, USA) were implanted in polyurethane foam biomechanics testing blocks. Five glenoid sizes, 40 mm, 44 mm, 48 mm, 52 mm and 55 mm (n = 5 per glenoid size), were cyclically tested according to ASTM Standard F-2028-08. A 44 mm humeral head (Affiniti, Tornier, Inc., Bloomington, MN, USA) was positioned centrally within the glenoid fixed to a materials testing frame (MTS Mini-Bionix II, Eden Prairie, MN, USA). Phase I testing (n = 3 per glenoid size) involved a subluxation test for determination of the humeral head translation distance which would be used for phase II cyclic testing. During cyclic loading, the humeral head was translated ± distance for 50,000 cycles at a frequency of 2 Hz, simulating approximately 5 years of device use. Glenoid compression, distraction, and superior-inferior glenoid translation were measured throughout testing via two differential variable reluctance transducers. Results:. Humeral head translation distance was identified as 0.55 mm, 1.09 mm, 2.32 mm, 3.82 mm, and 4.73 mm for each glenoid size, respectively (Figure 1). No significant difference was noted in 40 mm glenoids between cycle 1 and 50,000 for all parameters evaluated during testing (p > 0.05) (Figure 2). Conversely, a significant decrease in superior-inferior translation was present for 44 mm between cycle 1 and 50,000 (p = 0.010) (Figure 3). When analyzing all data from the first two smallest glenoid sizes, glenoid compression and translation both showed significantly increased micromotion with 40 mm glenoid sizes compared with the 44 mm glenoid size (p = 0.010 and p = 0.002, respectively). No significant difference was found with respect to glenoid distraction (p = 0.136). Conclusion:. The first phase of mechanical testing established the subluxation displacement of the humeral head against the glenoid for each prosthetic mismatch couple, which was larger for couples with greater glenohumeral mismatch. During cyclic testing, this displacement distance was covered in the same amount of time leading to differences in humeral head velocity and resultant stresses seen at the implant-cement-foam interfaces. A smaller mismatch in glenohumeral radius may lead to greater stress with shorter humeral translation compared to greater mismatch allowing for larger translations with lower resultant stresses. Data from our study will provide further clarification on the importance of glenohumeral mismatch on implant stability. Further studies are warranted to fully evaluate the impact and optimal amount radial mismatch for a clinical setting

The incidence of loosening of a cemented glenoid component in total shoulder arthroplasty, detected by means of radiolucent lines or positional shift of the component on true antero-posterior radiographs, has been reported to be between 0% to 44%. These numbers depend on the criteria used for loosening and on the length of follow-up. Radiolucent lines are however difficult to detect and to interpret, because of the mobility of the shoulder girdle and the obliquity of the glenoid, which hinder standardisation of radiographs. After review of radiolucencies around cemented glenoid components with a mean follow-up of 5. 3 years in 48 patients we found progressive changes to be present predominantly at the inferior pole of the component. This may hold a clue for the mechanism behind loosening of this implant. Since loosening is generally defined as a complete radiolucent line around the glenoid component and is difficult to assess as a result of the oblique orientation of the glenoid, an underestimation of the loosening rate using radiological data was suspected. Therefore a pilot study using Roentgen Stereophotogrammatric Analysis (RSA) was performed. In five patients an additional analysis of glenoid component loosening using digital Roentgen Stereophotogrammetric Analysis (RSA) was performed. The relative motion of the glenoid component with respect to the scapula was assessed and the length of this translation vector was used to represent migration. Loosening was defined as a migration of the component, exceeding the pessimistic estimate of the accuracy of RSA 0. 3 mm for this study. After three years of follow-up, three out of five glenoid components had loosened (1. 2 – 5. 5 mm migration). In only one patient with a gross loosened glenoid, the radiological signs were consistent with the RSA findings. It was concluded that when traditional radiographs are used for assessment of early loosening, the loosening rate is underestimated. We recommend that RSA be used for this

The purpose of the study was to describe the normal anatomy of glenoid labrum. Twenty dry bone scapulas and 19 cadaveric shoulders were examined. Light microscopy was performed on 12 radial slices through the glenoid. An external capsular circumferential ridge, 7–8mm medial to the glenoid rim marks the attachment of the capsule. A separate internal labral circumferential ridge 4mm central to the glenoid rim marks the interface for the labrum and articular cartilage. A superior-posterior articular facet contains the superior labrum. Two thirds of the long head of biceps arise from the supraglenoid tubercle, the remainder from the labrum. The superior labrum is concave and is loosely attached to the articular cartilage and glenoid rim. In contrast the anterior-inferior labrum is convex, attaches 4mm central to the glenoid rim and has a strong attachment to articular cartilage and bone. The anatomy of the superior and anteroinferior labrum are fundamentally different. Suture anchor repair of the superior labrum should be 7mm medial to the glenoid rim whereas the anterior-inferior labrum should be repaired to the face of the glenoid. By defining the normal anatomy of the superior labrum, pathological tears can be identified

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

Introduction: Fractures of the scapula are rare injuries. When they do occur, they are usually caused by high-energy trauma and some of the patients may have significant associated injuries. Most fractures are minimally displaced and amenable to nonsurgical treatment. Open reduction and internal fixation of intra-articular fractures are considered if there is a glenohumeral sub-luxation secondary to fracture or if there is an intra-articular displacement greater than 5 mm. Patients and Methods: This study consisted of 33 Pts from Israel and Macedonia (28 M, 5F, 18–74 year old, mean 43.5Y) followed for 2–5 years (mean 3.5Y). Fractures were classified according to Idelberg following analysis of plain radiographs and computerized radiographs. 26 patients had undisplaced or minimally displaced fractures of the glenoid and were treated conservatively by collar and cuff for three weeks, then followed by physiotherapy. The remaining seven patients had comminuted fractures with marked displacement of the glenoid and some degree of shoulder subluxation and were treated surgically. Six patients were treated by open reduction and osteosynthesis by rigid plates (3) or by screws alone (3). The 7. th. patient who was treated surgically, a 73-year-old female, had a displaced fracture of the glenoid associated with comminuted fracture of the proximal humerus. She was treated by internal fixation of the fractured glenoid by 2 screws, followed by hemi-arthroplasty of the shoulder. All patients were evaluated by the Constant’s Shoulder Score and by radiographs. Results: Overall results were excellent and good in 27/33 Pts (82%). They were almost free of pain and most of them had almost complete ROM of the affected shoulder. In the group of the patients treated conservatively for undisplaced or minimal displaced fractures of the glenoid 22/26 (85%) had satisfactory results. Five of the patients treated surgically (71%) had excellent and good results, with some better results in less comminuted fractures. The remaining 2/7 Pts treated surgically had fair results. One of them had a comminuted fracture of the glenoid and the other patient had an associated compound fracture of the proximal humerus and a shoulder hemiarthroplasty. Conclusions: Based on this study it seems that most fractures of the glenoid – undisplaced or minimally displaced – can be treated conservatively. However, for patients with displaced glenoid fractures, best results can be obtained with open reduction and internal fixation by screws or by plates. This should be followed by intensive physiotherapy

The incidence of total shoulder arthroplasty continues to increase. The most common reason for failure of a total shoulder arthroplasty is the glenoid component. Two styles of cemented all-polyethylene components are commonly implanted. These two styles are pegged glenoid and keel glenoid components. Data regarding the superiority of the styles has focused on radiolucent lines, complete loosening and need for revision procedures. Several retrospective and randomised controlled trials have been published to examine these endpoints. There is a trend in the literature to demonstrate decreased rates of radiolucent lines with pegged glenoid components, but a recent systematic review of available trials did not demonstrate a significant difference in the rate of radiolucent lines between the two styles. A slightly increased rate of revision was noted for the keel components. Overall pegged and keel glenoids both still represent good options in total shoulder arthroplasty

Introduction:. Subchondral bone density (SBD) distribution is an important parameter regarding that may be important when considering implant stability. This parameter is a reflection of the loading experienced by the joint throughout the lifetime and may be useful in pre-surgical planning and implant design. Clinically, the question of the glenoid surface preparation for TSA/RSA remains controversial, despite numerous published studies on glenoid bone morphology. To address this question, there exists a need to develop a 3D quantitative method capable of analyzing the complex glenoid bone morphology at different depths from the surface. Computed tomographic osteoabsoptiomery (CT-OAM) evaluates SBD based on the Housfield Unit (HU) value of each pixel. In this pilot study, we aimed to analyze SBD distribution of the glenoid at different depths by means of CT-OAM in male TSA subjects. Materials and Methods:. A study group of twenty male TSA patients (61–69y.o) were included in this study. Each subject obtained a pre-operative CT scan following a standardized protocol on the same CT scanner (1.25 mm slice thickness). Resultant DICOM 2D images were processed in custom-written program (VC++) and the surface of every glenoid was manually traced from the axial slices. Care was taken during the manual tracing process to exclude osteophytes and cyst formations from the resultant surface. Values of HU at every selected pixel on the surface of the glenoid were recorded. Subsequently, the layer of pixels at a 0.5 mm distance from the previous surface was virtually scraped and the HU values of new layer of pixels were recorded. This routine was repeated up to a depth of 5 mm from the glenoid surface, taking measurements on 11 virtual 3D surfaces with a thickness of 0.5 mm. Mean SBD distribution was reported for each layer and differences were compared using ANOVA and Fisher's post-hoc test. Results:. Apparent differences in mean SBD distribution were identified at every measured depth from the glenoid surface (Fig. 1). Significant differences (Tab.1) were identified between the middle range of studied surfaces (2.5–4.5 mm) when compared to the superficial (0–1.5 mm, p < 0.0001) and deep layers (5 mm, p < 0.0001). The maximum mean value of HU (1635.9 ± 35.5) was measured at 3.5 mm depth and the minimum value of HU was measured on the surface of the glenoid (1445.8 ± 31.3). Discussion:. The stability of the glenoid component in TSA prostheses is highly dependent on the SBD distribution. Controversy among orthopaedic surgeons exists regarding the depth of reaming required to prepare an arthritic glenoid. Extensive reaming may lead to the violation of the support provided by the denser subchondral bone; however, optimal match between the bone and glenoid component undersurface is highly desirable. This study demonstrates that the density of the bone is sustained up to a depth of approximately 4.5 mm from the glenoid surface, suggesting that an increased reaming may be favorable without compromising bony support

Aims. Radiostereometric analysis (RSA) allows an extremely accurate measurement of early micromotion of components following arthroplasty. . Patients and Methods. In this study, RSA was used to measure the migration of 11 partially cemented fluted pegged glenoid components in patients with osteoarthritis who underwent total shoulder arthroplasty using an improved surgical technique (seven men, four women, mean age 68). Patients were evaluated clinically using the American Shoulder and Elbow Surgeons (ASES) and Constant-Murley scores and by CT scans two years post-operatively. . Results. There were two patterns of migration, the first showing little, if any, migration and the second showing rotation by > 6° as early as three months post-operatively. At two years, these two groups could be confirmed on CT scans, one with osseointegration around the central peg, and the second with cystic changes. Patients with osteolysis around the central peg were those with early migration and those with osseointegration had minimal early migration. Both groups,however,had similar clinical results. . Conclusion. Rapid early migration associated with focal lucency and absence of osseointegration was observed in three of 11 glenoid components, suggesting that lack of initial stability leads to early movement and failure of osseointegration. Cite this article: Bone Joint J 2017;99-B:674–9

Background:. Glenoid component loosening remains as an unsolved clinical problem in total shoulder arthroplasty. Current clinical assessment relies on subjective quantification using a two-dimensional plane X-ray image with arbitrarily defined criteria. There is a need to develop a readily usable clinical tool to accurately and reliably quantify the glenoid component motion over time after surgery. A high-resolution clinical CT has the potential to quantify the glenoid motion, but is challenged by metal artifact from the prosthetic humeral components. The objective of this study is to demonstrate the feasibility of using a clinical CT reconstruction to quantify the glenoid implant motion with the aid of tantalum markers. Methods:. Three spherical tantalum markers of 1.0 mm in diameter were inserted into three peripheral pegs of an all polyethylene glenoid component. The glenoid component was implanted in a sawbone scapula. To determine the effect of metal artifact on quantification of glenoid implant motion, two sawbone humerii were used: one without the prosthetic humeral components and the other with the prosthetic humeral head and stem. Three custom-made translucent spacers with the uniform thickness were placed between the glenoid component and the scapula to produce a gradual translation of the glenoid component from 1 mm to 3 mm. Before and after inserting each spacer, the surface of the glenoid component was digitized by a MicroScribe. The surface points were used to fit a sphere and the corresponding center of the sphere was calculated. The actual translation of the glenoid component was measured as the three-dimensional (3D) distance between the center of the sphere before and after insertion of each spacer. Then, the shoulder model was scanned by a clinical CT with and without the spacers for both humerii conditions. Velcro straps were used to secure the humerus to the glenoid component between the trials. All CT scans were reconstructed in VolNinja software to superimpose the scapula positions (Figure 1). The three tantalum markers were visualized and the center coordinates of the markers were used to measure the 3D distance before and after insertion of each spacer. The accuracy was defined by the difference between the averaged 3D distance measured by CT reconstruction and that measured by the MicroScribe. The standard deviation of the 3D distance measured by each tantalum marker was calculated to evaluate the reliability of the tantalum marker visualization. Results:. Without metal artifact, the accuracy and reliability of quantifying glenoid implant motion using a clinical CT were 0.4 mm and 0.2 mm, respectively (Figure 2). With the presence of metal artifact, the accuracy and reliability were 0.5 mm and 0.4 mm, respectively. The largest difference in quantifying the glenoid component motion with and without the metal artifact was only 0.12 mm. Conclusion:. The current study demonstrated the feasibility of using a clinical CT to quantify glenoid implant motion. With the aid of tantalum markers, a clinical CT can be readily used to quantify the glenoid implant motion accurately and reliably even with the presence of metal artifact from the humeral components

Introduction. Hypoplasia of the glenoid is a rare condition caused by incomplete ossification of the postero-inferior aspect of the developing glenoid. It may be isolated or associated with a more generalised condition. The clinical symptomatology is variable depending on the age at time of presentation. Materials and Methods. We performed a retrospective chart review of patients who presented with shoulder complaints, and in whom a radiographic diagnosis of glenoid hypoplasia had been made. From January 2002 to December 2012, 8 patients (9 shoulders) with radiological signs of glenoid hypoplasia were identified. The mean age at presentation was 39 years (range 23 to 77) and the mean symptom duration was 12.5 months (range 1 to 48). Results. The diagnoses encountered included: impingement with rotator cuff tendonitis (2 shoulders), rotator cuff dysfunction with biceps tendonitis (1 shoulder), a SLAP lesion (2 shoulders), calcific tendonitis (1 shoulder), a posterior labral tear (1shoulder), multidirectional instability (1 shoulder), and adhesive capsulitis (1 shoulder). Of these nine, six shoulders were managed non-operatively and three were managed surgically, all with satisfactory results. The mean follow-up period was 30 months (range 5 to 60) and the mean Oxford shoulder score was 46.7 (range 42 to 48). Conclusion. We present a series of patients, who have been managed for a variety of shoulder pathologies, and in whom underlying glenoid hypoplasia has been diagnosed. NO DISCLOSURES

Assessing glenoid version is important for a successful total shoulder arthroplasty. Glenoid version is defined as the orientation of the glenoid cavity in relation to a plane perpendicular to the scapula body. Glenoid revision averages between 1 to 2 degrees of retroversion and varies between race and sex. In general glenoid retroversion is overestimated by 6.5 degrees on plain radiographs. Furthermore standard axial 2D CT is aligned to the patient's body and not aligned to the scapula. Therefore 3D reconstructions generated from standard CT allows for analysis of the scapula as a free body and correct version measurements can be made unaffected by positioning. If you add a computer modeling coordinate system in which implants can be added, then computer simulation surgery can be performed. This is important because implanting a glenoid component in excessive retroversion leads to increased stress at the glenoid component and cement mantle and decreased contact with the humeral component. Also excessive reaming of the glenoid surface to neutral retroversion can lead to excessive bone loss and penetration of the glenoid vault by either the pegs or the keel of the glenoid component

Introduction: Concern remains in loosening of glenoid component reversed prostheses. This study is to analyze glenoid location of stem and 4 screws of glenoid component. Material and method: 34 reversed prostheses included. Mean age 74,10, 33 females/1 male. Preoperative CT study : glenoid version; measure of anterior-posterior osteophytes. Postoperative CT study: central stem location and superior, inferior, anterior, posterior screws location. Study of influence of glenoid version and presence of osteophytes in location of glenoid implant. Results: 27 retroverted glenoids (mean 6,5°); 7 ante-verted (mean 5,3°). 17 cases with anterior osteophyte and 12 of posterior. In 52% the central stem was centered inside glenoid, 33% anterior end was outside glenoid and 14% the posterior end. When central stem was anteriorly outside 85% presented retroverted glenoid (mean 8,33°). When the central stem was posteriorly outside 66% presented anteverted glenoid (mean 9,5°). Inferior screw was fully in place in 38%, ¾ part inside in 19%, 2/4 part in 23%, ¼ part in 19%. Superior screw was fully in place in 47%, ¾ part inside in 23%, 2/4 part in 19%, ¼ part in 9%. Anterior screw was fully in place in 66%, ¾ part in 23% and 2/4 part in 9%. Posterior screw was fully in place in 38%, ¾ part in 42%, 2/4 part in 14%, ¼ part in 4%. The correct positioning of superior screw correlates with less coverture of inferior screw. Anterior and posterior osteophytes did not correlated with stem nor screw positioning. Conclusions: Positoning of central stem correlates with glenoid version. Anteriorly extruded stems correlate with higher retroverted glenoids and posteriorly extruded stems correlate with higher anteversion. Positioning the inferior screw fully inside the lateral border of the scapula correlates with lower bony coverture of superior screw

Introduction. Augmented glenoid implants provide a new avenue to correct glenoid bone loss and can possibly reconcile current prosthetic failures and improve long-term performance. Biomechanical implant studies have suggested benefits from augmented glenoid components but limited evidence exists on optimal design of these augmented glenoid components. The aim of this study was to use integrated kinematic finite element analysis (FEA) model to evaluate the optimal augmented glenoid design based on biomechanical performance in extreme conditions for failure. Materials and Methods. Computer aided design software (CAD) models of two different commercially available augmented glenoid designs - wedge (Equinox®, Exactech, Inc.) and step (Steptech®, Depuy Synthes) were created per precise manufacturer's dimensions and sizes of the implants. Using FE modeling, these implants were virtually implanted to correct 20° of glenoid retroversion. Two glenohumeral radial mismatches (RM) (3.5/4mm and 10 mm) were evaluated for joint stability and implant fixation to simulate high risk conditions for failure. The following variables were recorded: glenohumeral force ratio, relative micromotion (distraction, translation and compression), and stress on the implant and at the cement mantle interface. Results. The wedged and step designs showed similar force ratio measurements with both RM [(wedge (3.5 mm: 0.69; 10 mm: 0.7) and step (4 mm: 0.72; 10 mm: 0.75)]. Surrogate for micromotion was a combination of distraction, translation and compression. As radial mismatch increased, both implants showed less distraction [wedge design (3.5 mm: 0.042 mm; 10mm: 0.030 mm); step design (4 mm: 0.04 mm; 10 mm: 0.027 mm)]. As radial mismatch increased, both implants showed more translation [wedge design (3.5 mm: 0.058 mm; 10mm: 0.062 mm); step design (4 mm: 0.023 mm; 10 mm: 0.063 mm)]. During compression measurements, the different designs did not follow the same pattern as their conformity setting changed. The wedge one decreased as radial mismatch increased, (at 3.5mm: 0.18 mm; at 10 mm: 0.10 mm) and the step design increased as its radial mismatch increased (at 3.5 mm: 0.19 mm; at 10 mm: 0.25 mm). Quantitatively, the step design showed higher risk of implant instability and loosening. As radial mismatch increased, the stress level on the backside of the implant increased as opposed to the stress levels on the cement mantle which decreased for both designs as the radial mismatch increased [wedged (3.5 mm: 2.9 MPa; 10mm: 2.6 MPa); step (3.5 mm: 4.4 MPa; 10 mm: 4.1 MPa)]. In this situation, the risk of loosening was higher for the step designwhich exceeded the endurance limit of the cement material (4 MPa). Discussion. Implant loosening and wear are associated with increased micromotion and high stress levels. Based on our FEA model, overall increased radial mismatch has an advantage of providing higher glenohumeral stability but not without tradeoffs, such as higher implant and cement mantle stress levels, and micromotion increasing the risk of implant loosening, failure or fracture over time, leading to poorer clinical outcomes and higher revision rates, especially when considering a step augmented glenoid design

INTRODUCTION. The advent of CT based 3D preoperative planning software for reverse total shoulder arthroplasty (RTSA) provides surgeons with more data than ever before to prepare for a case. Interestingly, as the usage of such software has increased, further questions have appeared over the optimal way to plan and place a glenoid implant for RTSA. In this study, a survey of shoulder specialists from the American Shoulder and Elbow Society (ASES) was conducted to examine thought patterns in current RTSA implant selection and placement. METHODS. 172 ASES members completed an 18-question survey on their thought process for how they select and place a RTSA glenoid implant. Data was collected using a custom online Survey Monkey survey. Surgeon answers were split into two cohorts based on number of arthroplasties performed per year: between 0–75 was considered low volume (LV), and between 75–200+ was considered high volume (HV). Data was analyzed for each cohort to examine differences in thought patterns, implant selection, and implant placement. RESULTS. 70 surgeons were grouped into the LV cohort, and 102 surgeons were grouped into the HV cohort. 46.1% of surgeons in the HV cohort reported using a preoperative planning software for the majority of cases, 48% reported seldom use, and 5.9% reported no use. In the LV cohort, 41.4% reported use for the majority of cases, 24.3% reported seldom use, and 34.3% reported no use (Figure 1). When questioned on what percentage of RTSA cases do surgeons use augmented glenoid implants, 26.7% in the HV cohort responded never using augments vs. 32.4% in the LV cohort, 32.7% responded using augments <15% of the time in the HV cohort vs. 30.9% in the LV cohort, 26.7% responded using augments between 15–45% of the time in the HV cohort vs. 27.9% in the LV cohort, and 13.8% responded using augments >45% of the time in the HV cohort vs. 8.8% in the LV cohort (Figure 2). When asked what the maximum allowable superior inclination for a RTSA glenoid implant is, surgeons answered 10° 20.6% of the time in the HV cohort vs. 30% in the LV cohort, 5° 18.6% of the time in the HV cohort vs. 25.7% in the LV cohort, 0° 38.2% of the time in the HV cohort vs. 25.7% in the LV cohort, and no fixed degree 22.5% of the time in the HV cohort vs. 18.6% in the LV cohort (Figure 3). CONCLUSION. The results of this study show that even within a group of highly trained surgeons, there are widely varying opinions on how to plan the optimal RTSA case. Variation between high and low volume surgeons reveals even greater differences, suggesting that experience affects thought pattern. Despite these differences, there is no way to prove the optimal implant selection and placement without consistent data collection and long-term clinical outcomes. Machine learning on large preoperative planning databases combined with clinical outcomes data may provide further clarity on optimal implant placement and selection. For any figures or tables, please contact the authors directly

Radiolucent lines in total shoulder arthroplasty around the glenoid component are not uncommon in post-operative x-rays and the incidence varies. A certain percentage progress and as the lines enlarge can lead to component loosening. One study reported a 9% incidence at 2 years and 27% incidence at 5 years. A recent long term study (15 to 20 years) reported a 73% incidence. Radiolucent lines can be caused by anatomy (posterior glenoid wear) or pathology (inflammatory arthritis) as well as technical factors such as glenoid implant design (metal back) and improper implantation techniques where the prosthesis is not fully seated or cement is used to fill a defect. Every attempt should be made to avoid lucent lines. Minimal bone should be removed from the glenoid vault and a pressure injection type of insertion is helpful in getting the cement into the cancellous bone. Furthermore a peg type of glenoid implant rather than a keel type is preferred as this has been associated with a lower incidence of radiolucent lines

The Latarjet procedure utilises the coracoid as a vascularised bone autograft to augment the glenoid in patients with shoulder dislocation, especially where there is a bony lesion affecting the glenoid. A modification of the Latarjet procedure, pioneered in Cape Town, South Africa, rotates the coracoid so that its curved under-surface matches that of the glenoid. The aim of this study was to measure the radii of curvature of the glenoid and the coracoid to see how well the curved under-surface of the coracoid matches the glenoid’s surface curvature. An initial study of 210 cadaveric scapulae was performed in which the radii of curvature of the surface of the glenoid and the curved under-surface of the coracoid were measured. We found that the curves are very similar. The glenoid’s surface had a median curvature of 30mm (inter-quartile range from 25mm to 30mm) and the coracoid had a median curvature of 22.5mm (inter-quartile range from 20mm to 25mm). The curvature of the glenoid in these dry specimens was slightly larger than the corresponding coracoid curvature. In life this difference would be minimised by articular cartilage, labrum and the attachment of capsule (another Cape Town modification). A further parallel CT based study was set up at Derbyshire Royal Infirmary in England. The same radii of curvature where measured and compared using 3D CT reconstruction on a further 20 scapulae from living patients. These measurements also support the cadaveric similarities with a mean glenoid curvature of 23.9mm and coracoid of 25.4mm respectively. Using a paired t-test no statiscally significant difference was found between the corresponding data (p=0.2488). This study confirms the native anatomy of the coracoid is perfectly suited for this modification of the Latar-jet procedure

Glenoid replacement is technically challenging. Removal of a cemented glenoid component often results in a large osseous defect which makes the immediate introduction of a revision prosthesis almost impossible. We describe a two-stage revision procedure using a reversed shoulder prosthesis. Freeze-dried allograft with platelet-derived growth factor was used to fill the glenoid defect. Radiological incorporation of the allograft was seen and its consistency allowed the placement of a screwed glenoid component. There were no signs of new mature bone formation on histological examination. The addition of platelet-derived growth factor to the allograft seems to contribute to an increase in incorporation and hardness, but does not promote the growth of new bone

The purpose of the study was to describe the normal anatomy of glenoid labrum. 20 dry bone scapulas and 19 cadaveric shoulders were examined. Light microscopy was performed on 12 radial slices through the glenoid. An external capsular circumferential ridge, 7–8mm medial to the glenoid rim marks the attachment of the capsule. A separate internal labral circumferential ridge 4mm central to the glenoid rim marks the interface for the labrum and articular cartilage. A superior-posterior articular facet contains the superior labrum. Two thirds of the long head of biceps arise from the supraglenoid tubercle, the remainder from the labrum. The superior labrum is concave and is loosely attached to the articular cartilage and glenoid rim. In contrast the anterior-inferior labrum is convex, attaches 4mm central to the glenoid rim and has a strong attachment to articular cartilage and bone. The anatomy of the superior and anterior-inferior labrum are fundamentally different

Background. Radiological and clinical results of total shoulder arthroplasty are dependent upon ability to accurately measure and correct glenoid version. There are a variety of imaging modalities and computer-assisted reconstruction programmes that are employed with varying degrees of success. We have compared three freely available modalities: unformatted 2D CT; formatted 2D CT; and 3D CT reconstructions. Methods. A retrospective analysis of 20 shoulder CT scans was performed. Glenoid version was measured at the estimated mid-point of the glenoid from unformatted 2D CT scans (Scapula body method) and again following formatting of 2D CT scans in the plane of the scapula (Friedman method). 3D scapula reconstructions were also performed by downloading CT DICOM images to OSIRIX 6 and plotting ROI points on Friedman's axis to most accurately define glenoid version. Both measurements taken from 2D CT were compared to those from 3D CT. Eleven CT scans were of male patients, 9 female. Mean age was 55.2 years (Range: 23–77 years). Fourteen scans were performed for trauma, 6 for arthroplasty. Twelve scans were of the left shoulder. Results. Mean glenoid version as measured on: unformatted 2D CT was −4.51 degrees (−29.67 – 7.22 degrees); formatted 2D CT was −2.04 degrees (−36.96 – 9.72 degrees); and on 3D reconstructions was −3.01 degrees (−32.57 – 14.33 degrees). Sixty percent of measurements taken on formatted 2D CT were within 3 degrees of those taken on 3D reconstructions, with 85% within 5 degrees. This proportion fell to 30% and 50% respectively on unformatted 2D CT. Discussion. In this small study measurements of glenoid version taken on formatted 2D CT demonstrated greater accuracy than unformatted 2D CT when comparing to 3D reconstruction measurements as the gold standard. Although we demonstrated no significant statistical difference between measurements in this pilot study we believe significance will be obtained as we increase our sample size

The shape of the glenoid can vary between pear and oval, depending on the presence of a glenoid notch. We measured the glenoid notch angle (the angle between the superior and inferior part of the anterior glenoid rim) in 53 embalmed cadavers and investigated its relationship with the labral attachment to the glenoid at that point. The attachment of the anterosuperior labrum at the site of the glenoid notch was classified as tight or loose or, in some cases, there was a sublabral foramen. The anterior labrum was then removed and digital images perpendicular to the glenoid notch were taken. Using a digital image analysis program, the angle of the glenoid notch was measured. In 37 shoulders (70%) the attachment of the labrum at the site of the glenoid notch was assessed as tight and in eight (15%) as loose. In eight shoulders (15%) a sublabral foramen was found. The mean glenoid notch angle was 153° in the loosely attached group, 159° in the sublabral foramen group and 168° in the group with a tight attachment. The presence of a glenoid notch was noted only when the glenoid notch angle was less than 170°. The glenoid notch angle is related to the attachment of the labrum. In the presence of a glenoid notch, there is more likely to be a loosely attached labrum or sublabral foramen. The loose attachment of the anterosuperior labrum may be a predisposing factor in traumatic anterior instability

Loosening of the glenoid component after Total Shoulder Arthroplasty is an established phenomenon with long-term follow-up studies showing radiolucency in 65% of glenoid components at 10 years (Stewart and Gray, 1997). Glenoid component designs are based on anthropometric measurements of normal shoulder joints. The purpose of this study was to study the surface anatomy of both bony and cartilaginous layers of the normal glenoid fossa in more detail. We have developed a reproducible and inexpensive technique of surface shape assessment using laser morphometric analysis and applied this to thirty normal glenoid fossae mounted in the scapular plane. Surface analysis was carried out before and after removal of the glenoid labrum and after papain digestion of the articular cartilage allowing assessment of the skeleton alone allowing comparison with other studies using bony or cartilaginous landmarks in assessment of glenoid version. Using a specially designed program, five equi-distant lines were placed across the glenoid from which analysis of the orientation of the fossa was determined. None of the scapulae presented a single surface that could be judged anteverted or retroverted by an amount representable by a single figure. All scapulae demonstrated a twist about the vertical axis. Two main types were identified. Type 1 – Superior retroversion (mean 16.0 degrees) becoming progressively less to the lower pole (mean 3.0 degrees). Type 2 – Retroverted superiorly, twisting to reach the position of maximal anteversion in the lower half of the glenoid, twisting back into more retroversion towards the lower pole. None of the specimens were morphologically equivalent to currently available glenoid prostheses. The surface shape of the glenoid is so variable that we should explore the relationship between this and the kinematics of the shoulder joint. There may be implications for the design of shoulder replacements and possibly custom prostheses

Contracture of the anterior musculature causes posterior humeral head subluxation and results in a posterior load concentration on the glenoid. This reduced contact area causes glenoid wear, humeral medialisation and eventually posterior instability. After arthroplasty that does not correct for this, posterior wear stress increases in the implant, across the cement mantle and bone thus increasing the risk of aseptic loosening over time. Correction of the posterior wear pattern at the time of arthroplasty of the shoulder is recommended. Asymmetric reaming of the glenoid has been recommended as a means to correct this deformity but leads to producing a smaller glenoid which is medialised. This shortening of the glenoid causes the stabilising muscle envelope to shorten and the glenoid vault to become much smaller in volume. These potential changes may have a destabilising effect on the implant leading to early loosening and secondary failure of the prosthetic implant. Other options include using an implant to make the correction of the deformity such as augmented glenoid components. Early uses of these implants were not successful mainly due to the design flaws of the early implants. Newer implants have made design changes to overcome these early failures. CT scan evaluation is important to determine the degree of correction that is needed to balance the glenohumeral joint. Correcting the deformity and keeping the muscle envelope at the appropriate tension may lead to better long term outcomes. These implants are currently in use but long term outcome studies are not yet available to determine their ultimate values to the patients

Objectives. To date, no study has considered the impact of acromial morphology on shoulder range of movement (ROM). The purpose of our study was to evaluate the effects of lateralization of the centre of rotation (COR) and neck-shaft angle (NSA) on shoulder ROM after reverse shoulder arthroplasty (RSA) in patients with different scapular morphologies. Methods. 3D computer models were constructed from CT scans of 12 patients with a critical shoulder angle (CSA) of 25°, 30°, 35°, and 40°. For each model, shoulder ROM was evaluated at a NSA of 135° and 145°, and lateralization of 0 mm, 5 mm, and 10 mm for seven standardized movements: glenohumeral abduction, adduction, forward flexion, extension, internal rotation with the arm at 90° of abduction, as well as external rotation with the arm at 10° and 90° of abduction. Results. CSA did not seem to influence ROM in any of the models, but greater lateralization achieved greater ROM for all movements in all configurations. Internal and external rotation at 90° of abduction were impossible in most configurations, except in models with a CSA of 25°. Conclusion. Postoperative ROM following RSA depends on multiple patient and surgical factors. This study, based on computer simulation, suggests that CSA has no influence on ROM after RSA, while lateralization increases ROM in all configurations. Furthermore, increasing subacromial space is important to grant sufficient rotation at 90° of abduction. In summary, increased lateralization of the COR and increased subacromial space improve ROM in all CSA configurations. Cite this article: A. Lädermann, E. Tay, P. Collin, S. Piotton, C-H Chiu, A. Michelet, C. Charbonnier. Effect of critical shoulder angle, glenoid lateralization, and humeral inclination on range of movement in reverse shoulder arthroplasty. Bone Joint Res 2019;8:378–386. DOI: 10.1302/2046-3758.88.BJR-2018-0293.R1