Functional and radiographic outcomes of reverse shoulder arthroplasty with a minimum follow-up of 10 years

BACKGROUND

The use of reverse shoulder arthroplasty (RSA) is becoming increasingly prevalent. However, few studies have been published reporting the long-term outcomes of RSA. This study aims to report the clinical, radiographic, and patient-reported outcomes of the Delta Xtend reverse shoulder prosthesis, performed by a single surgeon and with a minimum follow-up of 10 years.

METHODS

All RSA procedures performed between 2005 and 2012 were identified. Patients were contacted and invited for a follow-up visit including clinical assessment, radiographs, and patient-reported outcome measures. Patients with a follow-up of less than 10 years were excluded. The revision-free implant survival was calculated at 10 years. Between 2005 and 2012, 119 procedures in 116 patients meeting inclusion criteria were identified. Of these patients, 35 were deceased before reaching the 10-year follow-up and 23 could not be reached. In total, 63 RSAs could be included in 61 patients (response rate: 75%). The median follow-up was 11.7 years (interquartile range [IQR]: 10.5-13.2).

RESULTS

Of the 61 patients, 7 patients underwent a revision after a median of 3 years (IQR: 0.2-9.8) during the total follow-up period. The 10-year implant survival was 94% (95% confidence interval: 84-98). At final follow-up, the median anterior elevation was 135° (IQR: 130°-160°), the median abduction was 120° (IQR: 100°-135°), and the median level reached with internal rotation was L5 (IQR: sacrum-L5). The median Auto-Constant score was 68 (IQR: 53-78), the median Subjective Shoulder Value was 80 (IQR: 70-93), and the median pain score was 0.2/10 (IQR: 0-2). In total, radiographs could be obtained in 25 patients (40%). Scapular notching occurred in 10 patients (40%), which was classified as Sirveaux-Nerot grade IV in 3 patients (12%). Ossification occurred in 10 patients (40%), and stress shielding in 2 patients (8%). Radiolucencies were observed around the humeral component in 24 patients (96%) and around the glenoid component in 13 patients (52%).

CONCLUSION

The long-term results of RSA with a Delta Xtend prosthesis are favorable, with long-term improvement in range of motion and patient-reported outcome measures, and a satisfactory implant survival rate. Interestingly, the radiographical analysis showed high prevalence of signs associated with loosening, which did not seem to translate to high complication rates or inferior results.

Stemless reverse shoulder arthroplasty: clinical and radiologic outcomes with minimum 2 years' follow-up

BACKGROUND

Recently, a stemless reverse shoulder arthroplasty (RSA) design was developed to preserve bone stock. Clinical and radiologic studies of this design in larger cohorts with >100 patients are not frequent. The purpose of this study was to present the clinical and radiologic results of a newly developed stemless RSA implant. The hypothesis was that this design would provide similar clinical and radiologic results to other stemless implants, as well as stemmed implants.

METHODS

Between September 2015 and December 2019, all patients who underwent primary RSA with a stemless Easytech prosthesis were considered eligible for inclusion in this prospective multicenter study. The minimum follow-up period was 2 years. Clinical outcomes consisted of the Constant score, adjusted Constant score, QuickDASH (short version of Disabilities of the Arm, Shoulder and Hand questionnaire) score, Subjective Shoulder Value, and American Shoulder and Elbow Surgeons shoulder score. Radiographic parameters included radiolucency, loosening, scapular notching, and specific geometric parameters.

RESULTS

Stemless RSA was performed in 115 patients (61 women and 54 men) at 6 different clinical centers. The average age at the time of surgery was 68.7 years. The average Constant score was 32.5 preoperatively and showed significant improvement to 61.8 at latest follow-up (P < .001). The Subjective Shoulder Value also demonstrated significant improvement postoperatively (from 27.0 to 77.5, P < .001). Scapular notching was observed in 28 patients (24.3%); humeral loosening, 5 (4.3%); and glenoid loosening, 4 (3.5%). The total complication rate was 17.4%. Eight patients (4 women and 4 men) underwent implant revision.

CONCLUSION

The clinical outcomes of the examined stemless RSA seem to be comparable to those of other humeral designs; however, the complication and revision rates are higher than those of historical controls. Surgeons should proceed with caution when using this implant until longer-term follow-up data are available.

Neck shaft angle (NSA) in Reverse Shoulder Arthroplasty (RSA): 135 versus 145 degrees at minimum 2 years follow-up

BACKGROUND

The most common complication with Reverse Shoulder Arthroplasty (RSA) Grammont based design with a 155° neck shaft angle (NSA) is scapular notching. Scapular notching has been associated with both reduced clinical outcomes. Reducing the humeral neck shaft angle from 155 degrees has been shown to reduce the incidence of scapular notching however it is unknown whether there is a difference in scapular notching between a 145 and 135° NSA. The purpose of this study was to evaluate the effect of decreasing the NSA on scapular notching rate and postoperative range of motion comparing 145° and 135° NSA stems at minimum two year of follow-up.

METHODS

Consecutive patients undergoing primary RSA with a neck shaft angle of either 145° or 135° between January 2014 and February 2019 were retrospectively reviewed. Patients were included if they were over the age of 18, had minimum clinical follow-up of 24 months with true postoperative anteroposterior radiographic view.

RESULTS

One hundred and three patients were included for the final analysis: 73 with a 145° NSA and 30 with a 135° NSA stem. The mean age and mean follow-up were respectively 70.9 years (range, 52.0-89.0) and 32.1 months. The overall incidence of scapular notching was 46.6 %. There was a statistically significant difference in scapular notching between the 145° (53.4%) and 135° (30%) NSA groups (p=.028). There was no difference in terms of postoperative Constant-Murley Score (mean, 66.1 Vs 68.2; p =.395) , Subjective Shoulder Value (mean, 76,5 Vs 83.1%, p= .167), forward flexion (mean, 140° Vs 142°, p= .704), abduction (mean, 123.2° Vs 121.5° , p= .771), external rotation with the arm at the side (mean, 34.1° vs 37.3°, p= .341) and internal rotation (mean, 5.3 vs 5.4 pts p=.336) between the two groups.

CONCLUSION

This is the first study to compare the effect of a 145° vs 135° neck shaft angle on scapular notching rates. The key finding of this study is that scapular notching rate was significantly reduced from 53% to 30% in 135° NSA compared to 145° NSA, after at least 24 months of follow-up. Our data also shows suggests that glenoid lateralization and inferiorization has an influence on scapular notching. We are unable to state that the reduced scapular notching rate was due to a reduction in NSA alone. Despite a lower rate of scapular notching, the 135°NSA group has not shown any significant better clinical and functional outcomes.

Inlay versus onlay humeral design for reverse shoulder arthroplasty: a systematic review and meta-analysis

BACKGROUND

Since the introduction of the Grammont-style reverse total shoulder arthroplasty, the humeral stem design has been modified with improved clinical outcomes. Two distinct humeral designs have been used extensively: the inlay design, in which the humeral tray is seated within the metaphysis, and the onlay design, in which the humeral tray sits on the metaphysis at the level of the humeral neck cut. The purpose of this systematic review was to determine whether there are differences in clinical outcomes and complication rates between these designs.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used to perform this systematic review. A search of MEDLINE, PubMed, and Embase was performed to identify all studies comparing the clinical results of both humeral designs. Primary outcomes included patient-reported outcome measures, shoulder range of motion, and incidence of complications.

RESULTS

From the 156 identified publications, 12 studies were included in the final review. A total of 1447 patients were included, with a minimum follow-up period of 12 months. At final follow-up, both implants demonstrated significant improvements in comparison to preoperative baseline. On comparison of the inlay vs. onlay groups, the American Shoulder and Elbow Surgeons score was higher in the inlay group (mean difference, 2.53 [95% confidence interval, 0.27-4.78]; P = .03). Postoperative motion, even if statistically greater in the onlay group (differences of 5° in forward flexion [P < .001], 3° in abduction [P = .003], and 4° in external rotation [P < .001]), was not clinically different. On comparison of complications, the inlay group showed more instances of scapular notching (93 of 322 patients vs. 70 of 415 patients; odds ratio, 0.35; P < .001) but fewer scapular spine fractures (26 of 727 patients vs. 21 of 559 patients, P = .09).

DISCUSSION

Inlay and onlay humeral tray designs in reverse total shoulder arthroplasty demonstrate similar clinical improvements postoperatively. Onlay implants have a low rate of scapular notching but a higher rate of scapular spine fracture. Understanding the strengths and weaknesses of the 2 humeral tray designs is important to provide surgeons with options to tailor surgical plans for high-risk patients.

Clinical outcomes related to glenosphere overhang in reverse shoulder arthroplasty using a lateralized humeral design

BACKGROUND

Previous studies have demonstrated that decreased impingement-free range of motion (ROM) can adversely influence clinical outcomes following reverse shoulder arthroplasty (RSA). Inferior placement of the glenosphere is thought to minimize impingement and its associated sequelae. This study evaluated the relationship between inferior overhang of the glenosphere and clinical outcomes in patients undergoing primary RSA using a lateralized humeral implant design.

METHODS

By use of a prospectively collected shoulder arthroplasty database, all primary RSAs performed at our institution between 2007 and 2015 with a single implant design (lateralized humerus and medialized glenoid) and minimum 2-year follow-up were evaluated. Glenosphere overhang in relation to the inferior rim of the glenoid was measured in millimeters on postoperative Grashey radiographs of the shoulder and categorized into tertiles (low, <7.1 mm; medium, 7.1 to 9.9 mm; and high, >9.9 mm). Clinical outcomes of interest comprised the changes between preoperative and postoperative values in the following ROM and outcome score measures: active forward elevation (aFE), active external rotation, American Shoulder and Elbow Surgeons score, Constant-Murley score, Shoulder Pain and Disability Index score, and Simple Shoulder Test score. Random-effects linear models were used to assess univariate and multivariable associations between overhang tertile and change in patient outcomes. Differences in outcomes were further compared using the minimal clinically important difference (MCID).

RESULTS

The study identified 284 shoulders in 265 patients. The median follow-up period was 36 months (range, 24-108 months). The median glenosphere inferior overhang was 8.4 mm, with an interquartile range of 6.3-10.6 mm. Plots demonstrated nonlinear relationships between overhang and outcome scores and between overhang and ROM. Patients with high overhang experienced a significantly greater improvement in aFE compared with patients with low overhang (P = .019), which exceeded the MCID. No other differences in ROM and outcome scores between overhang groups exceeded the MCID. For other outcome scores and ROM measurements, there was no significant relationship with glenosphere overhang. Increased overhang was associated with a significantly lower incidence of scapular notching (P = .005).

CONCLUSION

Patients undergoing RSA using a lateralized humerus design with greater inferior overhang of the glenosphere demonstrated a significantly greater improvement in aFE and lower rate of notching compared with those with low overhang. No ideal glenosphere overhang range was identified to maximize function in this study.

Inverted-Bearing Reverse Shoulder Arthroplasty: Consequences on Scapular Notching and Clinical Results at Mid-Term Follow-Up

Background: Scapular notching following reverse shoulder arthroplasty (RSA) is caused by both biological and mechanical mechanisms. Some authors postulated that osteolysis that extends over the inferior screw is caused mainly by biological notching. Inverted-bearing RSA (IB-RSA) is characterized by a polyethylene glenosphere and a metallic humeral liner, decreasing the poly debris formation and potentially reducing high grades of notching. This study aims to report the results of IB-RSA on a consecutive series of patients at mid-term follow-up, focusing on the incidence of Sirveaux grade 3 and 4 scapular notching. Methods: A retrospective study on 78 consecutive patients who underwent primary IB-RSA between 2015−2017 was performed. At a 4 years minimum follow-up, 49 patients were evaluated clinically with Constant score (CS), Subjective shoulder value (SSV), American Shoulder and Elbow score (ASES), pain and range of motion, and with an X-ray assessing baseplate position (high, low), implant loosening, and scapular notching. Results: At a mean follow-up of 5.0 ± 0.9, all the clinical parameters improved (p < 0.05). One patient was revised for an infection and was excluded from the evaluation, two patients had an acromial fracture, and one had an axillary neuropraxia. Scapular notching was present in 13 (27%) patients (six grade 1, seven grade 2) and no cases of grade 3 and 4 were observed. Scapular nothing was significantly associated with high glenoid position (p < 0.001) and with lower CS (70 ± 15 vs. 58 ± 20; p = 0.046), SSV (81 ± 14 vs. 68 ± 20; p = 0.027), ASES (86 ± 14 vs. 70 ± 22; p = 0.031), and anterior elevation (148 ± 23 vs. 115 ± 37; p = 0.006). A 44 mm- compared to 40 mm-glenosphere was associate with better CS (63 ± 17 vs. 78 ± 11; p = 0.006), external (23 ± 17 vs. 36 ± 17; p = 0.036), and internal rotation (4.8 ± 2.7 vs. 7.8 ± 2.2; p = 0.011). Conclusions: IB-RSA is a safe and effective procedure for mid-term follow-up. Inverting biomaterials leads to a distinct kind of notching with mainly mechanical features. Scapular notching is associated with a high baseplate position and has a negative influence on range of motion and clinical outcome.

Which lateralization designed prosthesis of reverse total shoulder arthroplasty (glenoid-based lateralization vs humerus-based lateralization) would be better? Network Meta-analysis

PURPOSE

To demonstrate the differences between outcomes and complications after reverse total shoulder arthroplasty (rTSA), according to the types of lateralized prosthesis designs: glenoid-based lateralization (LG) and humerus-based lateralization (LH).

METHODS

PubMed, Embase, and the Cochrane Library databases were systematically searched for studies published before 1 April 2021, using the PRISMA guidelines. A network meta-analysis was applied for indirect comparison, incorporating studies including medialized or conventional Grammont prosthesis and each lateralized prosthesis (LG vs control and LH vs control). Out of 1,989 screened studies, 11 studies were included to compare functional scores, range of motion (ROM), radiologic outcomes, and revision rates. In addition, six articles from the included studies, which had repaired subscapularis after rTSA were analyzed to exclude the potential influence of subscapularis repair on the outcomes. The data were pooled using a random-effects model. The pooled estimates of the mean differences (MDs) and 95% confidence intervals (CIs) were calculated for continuous data, while dichotomous data were analyzed using the pooled relative risk (RR) and their 95% CIs.

RESULTS

The ROM, complications, and functional scores were similar between the two groups. In subgroup analysis of 6 studies involving concomitant subscapularis repair, the LH group showed higher American Shoulder and Elbow Surgeons (ASES) scores and Constant scores than the control group. Regarding the ROM, LH group showed better forward elevation than the LG group (LH vs LG: MD 10.07, 95% CI -9.05-29.19).

CONCLUSION

Overall, the outcomes and occurrence of complications were not significantly different between the two lateralized prosthesis groups. However, when the subscapularis was repaired, LH prosthesis seems to be more suitable to obtain a better ASES score and ROM.

LEVEL OF EVIDENCE

Level III, network meta-analysis.

The Role of Humeral Neck-Shaft Angle in Reverse Total Shoulder Arthroplasty: 155° versus <155°—A Systematic Review

The aim of this study was to have updated scrutiny of the influence of the humeral neck-shaft angle (HNSA) in patients who underwent reverse shoulder arthroplasty (RSA). A PRISMA-guided literature search was conducted from May to September 2021. Clinical outcome scores, functional parameters, and any complications were reviewed. Eleven papers were identified for inclusion in this systematic review. A total of 971 shoulders were evaluated at a minimum-follow up of 12 months, and a maximum of 120 months. The sample size for the "HNSA 155°" group is 449 patients, the "HNSA 145°" group involves 140 patients, and the "HSNA 135°" group comprises 291 patients. The HNSA represents an important variable in choosing the RSA implant design for patients with rotator cuff arthropathy. Positive outcomes are described for all the 155°, 145°, and 135° HSNA groups. Among the different implant designs, the 155° group show a better SST score, but also the highest rate of revisions and scapular notching; the 145° cohort achieve the best values in terms of active forward flexion, abduction, ASES score, and CMS, but also the highest rate of infections; while the 135° design obtains the best results in the external rotation with arm at side, but also the highest rate of fractures. High-quality studies are required to obtain valid results regarding the best prosthesis implant.

Medium- to Long-Term Outcomes after Reverse Total Shoulder Arthroplasty with a Standard Long Stem

Background: Long-term clinical and radiographic outcome data after standard cemented long-stem reverse shoulder arthroplasty (RSA) remain underreported. The aim of this study is to report on medium- to long-term data of patients over 60 years of age. Methods: The same type of RSA (Aequalis Reverse II, Memphis, TN, USA) was implanted in 27 patients with a mean age of 73 years (range 61−84). Indications for RSA were cuff tear arthropathy (CTA) in 25 cases and osteoarthritis (OA) in two cases. Pre- and postoperative Constant Score was assessed and component loosening, polyethylene wear, scapular notching and revision rates were recorded at a mean clinical follow-up (FU) of 127.6 months (SD ± 33.7; range 83−185). Results: The mean-adjusted CS (aCS) improved from 30.0 (range 10−59) to 95.0 (range 33−141) points (p < 0.001). Glenoid loosening was found in two (9.1%) and stem loosening was found in three (13.6%) cases. Polyethylene wear was observed in four (18.2%) cases. Scapular notching appeared in 15 (68.2%) cases but was not associated with poor aCS (p = 0.423), high levels of pain (p = 0.798) or external rotation (p = 0.229). Revision surgery was necessary in three (11.1%) cases. Conclusions: RSA with a cemented standard long stem leads to improvement in forward elevation, abduction and pain after a mean FU of 10 years. However, external rotation does not improve with this prosthetic design. Moreover, scapular notching is observed in the majority of cases, and revision rates (11.1%) as well as humeral loosening rates (13.6%) remain a concern. Level of evidence: Level 4, retrospective cohort study.

Medialized versus Lateralized Center of Rotation in Reverse Total Shoulder Arthroplasty: A Systematic Review and Meta-Analysis

One of the original biomechanical principles of reverse total shoulder arthroplasty (RTSA) is medialization of the center of rotation (COR) relative to the native level of the glenoid. Several authors have proposed the lateralized center of rotation, which is characterized by a lateralized (L) glenoid and medialized (M) humeral component. The aim of this review is to compare the clinical and functional outcomes of COR in medialized (M-RTSA) and lateralized (L-RTSA) RTSA in patients with uniform indications and treatment through a meta-analysis. A PRISMA-guided literature search of PubMed, Medline, Embase, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and Cochrane Clinical Answers was conducted from April to May 2021. Twenty-four studies were included in the qualitative synthesis, and 19 studies were included in the meta-analysis. Treatment with RTSA resulted in positive post-operative outcomes and low complication rates for both groups. Statistically relevant differences between L-RTSA group and M-RTSA group were found in post-operative improvement in external rotation with arm-at-side (20.4° and 8.3°, respectively), scapular notching rates (6.6% and 47.7%) and post-operative infection rates (1% and 7.7%). Both lateralized and medialized designs were shown to improve the postoperative outcomes. Nevertheless, a lateralized COR resulted in greater post-operative external rotation.

Complications of Reverse Total Shoulder Arthroplasty: A Computational Modelling Perspective

Reverse total shoulder arthroplasty (RTSA) is an established treatment for elderly patients with irreparable rotator cuff tears, complex proximal humerus fractures, and revision arthroplasty; however, with the increasing indications for RTSA over the last decade and younger implant recipients, post-operative complications have become more frequent, which has driven advances in computational modeling and simulation of reverse shoulder biomechanics. The objective of this study was to provide a review of previously published studies that employed computational modeling to investigate complications associated with RTSA. Models and applications were reviewed and categorized into four possible complications that included scapular notching, component loosening, glenohumeral joint instability, and acromial and scapular spine fracture, all of which remain a common cause of significant functional impairment and revision surgery. The computational shoulder modeling studies reviewed were primarily used to investigate the effects of implant design, intraoperative component placement, and surgical technique on postoperative shoulder biomechanics after RTSA, with the findings ultimately used to elucidate and mitigate complications. The most significant challenge associated with the development of computational models is in the encapsulation of patient-specific anatomy and surgical planning. The findings of this review provide a basis for future direction in computational modeling of the reverse shoulder.

Early restoration of shoulder function in patients with the Grammont prosthesis compared to lateralized humeral design in reverse shoulder arthroplasty

BACKGROUND

This study aimed to compare the clinical outcomes and radiographic parameters of patients after reverse shoulder arthroplasty (RSA) between the Grammont prosthesis and lateralized humeral design prosthesis.

METHODS

A total of 114 patients who underwent RSA with a lateralized humeral design (group L; 71 shoulders) and medialized humeral design (group M; 43 shoulders) prosthesis for cuff tear arthropathy or irreparable rotator cuff tear were enrolled. Clinical outcomes including visual analog scale (VAS), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), and Constant scores and range of motion (ROM) were serially followed up at postoperative 3, 6, 12, and 24 months. Radiographic parameters were measured to evaluate preoperative and postoperative status.

RESULTS

Both prostheses demonstrated similar clinical outcomes and shoulder function preoperatively and at postoperative 2 years (P >.05). However, patients in group M had significantly better postoperative active forward flexion (postoperative 3 months, 115° ± 12° vs. 101° ± 14°; P <.001; 6 months, 125° ± 13° vs. 118° ± 13°; P <.013) and abduction (3 months, 105° ± 12° vs. 98° ± 12°; P = .002); VAS (3 months, 3.1 ± 1.2 vs. 3.7 ± 1.4; P = .031; 6 months, 2.3 ± 1.1 vs. 2.8 ± 1.3; P = .038); ASES (3 months, 64.2 ± 7.0 vs. 60.4 ± 9.2; P = .022; 6 months, 70.6 ± 6.0 vs. 66.6 ± 8.1; P = .007); and Constant scores (6 months, 59.6 ± 6.9 vs. 55.7 ± 9.3; P = .020). Group L showed a significantly lower rate of scapular notching than group M (15.5% vs. 41.8%; P < .001). The position of the proximal humerus in group L was more lateralized and less distalized than in group M after RSA.

CONCLUSIONS

RSA with both the Grammont and lateralized humeral design prostheses provided similar shoulder ROM restoration and functional improvements at a minimum of 2 years. However, patients with a humeral lateralized prosthesis showed slower recovery of shoulder function and ROM up to postoperative 6 months despite a lower incidence of scapular notching.

Mechanical complications and fractures after reverse shoulder arthroplasty related to different design types and their rates: part I

The initial reverse shoulder arthroplasty (RSA), designed by Paul Grammont, was intended to treat rotator cuff tear arthropathy in elderly patients. In the early experience, high complication rates (up to 24%) and revision rates (up to 50%) were reported.The most common complications reported were scapular notching, whereas clinically more relevant complications such as instability and acromial fractures were less commonly described.Zumstein et al defined a 'complication' following RSA as any intraoperative or postoperative event that was likely to have a negative influence on the patient's final outcome.High rates of complications related to the Grammont RSA design led to development of non-Grammont designs, with 135 or 145 degrees of humeral inclination, multiple options for glenosphere size and eccentricity, improved baseplate fixation which facilitated glenoid-sided lateralization, and the option of humeral-sided lateralization.Improved implant characteristics combined with surgeon experience led to a dramatic fall in the majority of complications. However, we still lack a suitable solution for several complications, such as acromial stress fracture. Cite this article: EFORT Open Rev 2021;6:1097-1108. DOI: 10.1302/2058-5241.6.210039.

Scapular Notching Following Ipsilateral Traumatic Clavicle Fracture in Reverse Total Shoulder Arthroplasty: A Case Report

Introduction

Reverse total shoulder arthroplasty (RTSA) procedures are becoming increasingly more common. While the main complications are known, the management of clavicle fractures in patients with an ipsilateral RTSA is not well described. There are three case studies that document clavicular stress fractures following RTSA with an atraumatic etiology, and to our knowledge, no studies have described a traumatic clavicular fracture following RTSA.

Case

We describe the case of a 75-year-old woman with a traumatic clavicle fracture five years after RTSA for rotator cuff tear arthropathy. With minimal pain and subjective symptoms initially, the patient wished to pursue non-operative treatment. However, she eventually developed a painful non-union and pseudoparalysis of the shoulder with serial radiographs demonstrating progressive superior scapular tilting and scapular notching. Subsequent open reduction internal fixation of her clavicle fracture significantly improved her pain and function.

Conclusion

We report a traumatic clavicle fracture in the setting of RTSA that not only failed to heal but also resulted in scapular notching and shoulder pseudoparalysis that was improved with surgical stabilization of the fracture. It is possible that the setting of a semi-constrained RTSA, the resulting biomechanical imbalance may predispose to impaired fracture healing and non-union of the clavicle fracture.

Clinical and radiologic outcomes of eccentric glenosphere versus concentric glenosphere in reverse shoulder arthroplasty

BACKGROUND

The use of an eccentric glenosphere (EG) has been proposed as a way to prevent scapular notching in reverse shoulder arthroplasty (RSA). The purpose of this study was to investigate whether the use of an EG decreases scapular notching compared with matched standard concentric glenosphere (CG) controls.

METHODS

A retrospective analysis was performed. This study included 49 RSAs with an EG and 49 paired RSAs with a CG with a minimum 60 months of both clinical and radiographic follow-up. Clinical and radiologic outcomes of the EG and CG groups were compared at inclusion and at the last follow-up using the paired Student t test for quantitative data and the χ² test for qualitative data. Scapular notching was graded according to the Sirveaux classification. Statistical significance was set at P < .05.

RESULTS

Notching was observed 2.7 times (95% confidence interval, 1.0-6.8 times) more often in the CG group (P = .037). The difference in notching severity between the groups was not statistically relevant; however, there was a trend toward more severe notching in the CG group (P = .059). Compared with a CG, an EG did not increase the percentage of radiolucent lines around the screws (3% vs. 1.5%, P = .62), around the post (3% vs. 1.5%, P = .62), or below the baseplate (15% vs. 7.5%, P = .18).

CONCLUSION

EGs are associated with less notching than CGs. This finding confirms that RSA with an EG is an effective procedure without specific complications at a minimum follow-up of 5 years.

Wear and damage in retrieved humeral inlays of reverse total shoulder arthroplasty-where, how much, and why?

BACKGROUND

Polyethylene (PE) wear and material degradation have been reported as complications in reverse total shoulder replacements (rTSAs). In this regard, scapular notching is associated with more clinical complications. Therefore, the purposes of the study were to quantify the linear and volumetric wear, as a measure for the amount of removed material, and to qualitatively assess the PE damage modes to describe the material degradation in retrieved rTSA humeral PE inlays that contribute to failure of shoulder replacements. Furthermore, this study aimed to evaluate the effect of scapular notching on PE wear and rim damage of the humeral components.

METHODS

The total study population of 39 humeral inlays contains 2 cohorts that were used for the damage mode analysis and for the wear analysis, respectively. The extent and presence of wear damage modes in 5 defined zones were assessed by a grading system for all PE joint replacements. For quantitative wear analysis the most frequent design (n = 17) was chosen. Using a coordinate-measuring machine and postprocessing software, volumetric wear measurements for the retrieved humeral PE inlays were undertaken. Furthermore, prerevision radiographs were analyzed for scapular notching. Finally, retrieval findings were correlated with clinical and radiographic data to consider the effect of notching and to identify risk of failures for these prostheses.

RESULTS

Damage on the rim of the humeral PE inlays was more frequent and severe than on the intended articulation surface. Irrespective of the damage mode, the inferior rim zone sustained the greatest amount of wear damage followed by the posterior zone. Burnishing, scratching, pitting, and embedded particles are most likely to occur in the articular surface area, whereas surface deformation, abrasion, delamination and gross material degradation are predominantly present in the inferior and posterior rim zones. The retrieved inlays exhibited a mean volumetric wear rate of 296.9 mm³/yr ± 87.0 mm³/yr. However, if the notched and non-notched components were compared, a significant higher volumetric wear rate (296.5 ± 106.1 mm³/yr) was found for the notched components compared to the non-notched group (65.7 ± 7.4 mm³/yr). Generally, there was a significantly greater incidence of damage and greater amount of wear if scapular notching occurred.

CONCLUSION

The notched components showed a 5-fold increase in PE wear rate. Therefore, scapular notching has a strong effect on PE damage and wear. If scapular notching can be clinically avoided, the PE wear performance is in a similar magnitude as found for hip and knee replacements.

Lateralized versus nonlateralized glenospheres in reverse shoulder arthroplasty: a systematic review with meta-analysis

HYPOTHESIS/BACKGROUND

Lateralization in reverse shoulder arthroplasty (L-RSA) was proposed to overcome some limitations of the original Grammont-style design (S-RSA). This systematic review aims to compare the clinical and functional outcomes and complications of S-RSA with L-RSA, and to assess the individual results of metallic and bony lateralization implants.

METHODS

A systematic search from January 1980 to December 2019 was performed. Studies were selected in 2 phases by 2 independent reviewers; disagreements were solved by discussion. Inclusion criteria were: (1) original studies; (2) written in English or French; (3) adult individuals submitted to RSA surgery; and (4) RSA with a lateralization device in at least one of the groups. Exclusion criteria were: (1) nonoriginal studies or case reports; (2) absence of clinical or radiographic outcomes; and (3) no comparison group using S-RSA. Data were extracted for outcomes of functional status (American Shoulder and Elbow Surgeons, Constant, visual analog scale, Simple Shoulder Test, Subjective Shoulder Value, Activities of Daily Life that require External Rotation, and Disabilities of the Arm, Shoulder, and Hand), range of motion (ROM), complications, revisions, and notching. Meta-analyses were performed when possible. Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed.

RESULTS

Fifteen articles/16 studies were included (865 participants: 440 L-RSA and 425 S-RSA). Most studies found no differences between the L-RSA and S-RSA groups in qualitative and meta-analysis for American Shoulder and Elbow Surgeons, Constant, Simple Shoulder Test, Activities of Daily Life that require External Rotation, and Disabilities of the Arm, Shoulder, and Hand scores. Meta-analysis demonstrated significantly lower visual analog scale (1 point) and higher Subjective Shoulder Value (6 points) in L-RSA than in S-RSA. No significant differences were found in the qualitative analyses of most studies regarding ROM in forward elevation, abduction, and internal/external rotation, but meta-analysis reported a significantly higher external rotation in L-RSA groups and specifically in osseous lateralization. Complication rate was significantly lower in L-RSA (odds ratio = 0.38), but no significant differences were found for revision rates. Notching rate was significantly lower in the L-RSA group (odds ratio = 0.14), both for osseous and metallic lateralization.

DISCUSSION/CONCLUSION

This systematic review focused on studies comparing L-RSA and S-RSA and found significantly lower notching and complication rates in L-RSA groups. This review highlighted similar outcomes in clinical scores and a slight advantage for L-RSA in ROM, especially in external rotation. L-RSA was not associated with increased revision rates, while presenting lower complication and notching rates. Inclusion of studies with metallic and osseous lateralization has helped to provide further evidence on this subject, but heterogeneity and low evidence levels of the included studies may limit our conclusions.

Inferior tilt of the glenoid leads to medialization and increases impingement on the scapular neck in reverse shoulder arthroplasty

BACKGROUND

In reverse shoulder arthroplasty, Inferior tilt was originally promoted to decrease rates of baseplate failure. However, the literature is conflicting regarding the effect of tilt on scapular neck impingement, which has been associated with an increased risk of notching, increased risk of impingement-related instability, and decreased range of motion. We hypothesized that inferior tilt of -10° would lead to increased medialization and increased scapular neck impingement compared with 0° of tilt.

METHODS

Twenty patients without glenoid bone loss undergoing reverse shoulder arthroplasty (RSA) at a single institution underwent computed tomography scans of the entire scapula and proximal humerus for preoperative planning. For each patient, we digitally implanted a 25-mm glenoid baseplate flush with the inferior rim of the glenoid. We then simulated impingement-free range of motion with 16 different implant configurations: glenoid tilt (0° vs. -10°), baseplate lateralization (0 mm vs. +6 mm), glenosphere size (36 mm vs. 42 mm), and neck-shaft angle (135° vs. 145°). The primary endpoint was external rotation with the arm at the side (ERS), which is the primary mode of both notching and impingement-related instability, and the secondary endpoint was adduction (ADD). We recorded the RSA angle, preoperative scapular neck length (SNL), and postoperative SNL. Data were compared by paired t tests and a multivariable regression analysis.

RESULTS

In every simulation, inferior tilt led to more impingement on the scapular neck. Inferior tilt of the glenoid component was associated with a mean 27% decrease in impingement-free external rotation (P < .01 in all cases) and a mean 32% decrease in impingement-free ADD (P < .01 in all cases). Inferior tilt removed 3.2 mm of additional SNL (P < .001). Multivariable regression analysis showed that lateralization had the most impact on impingement-free external rotation and ADD (P < .001), followed by glenosphere size (P < .001), neck-shaft angle (P < .001), postoperative SNL (P < .001), glenoid tilt (P = .001), inclination (P < .001), and RSA angle (P = .023 for ERS and P = .025 for ADD).

CONCLUSION

Relative to 0° of tilt of the baseplate, inferior tilt of -10° was associated with increased scapular neck impingement in ERS and ADD, likely a result of the increased medialization necessary to seat an inferiorly tilted implant, which shortens the scapular neck and brings the humerus closer to the scapula. This scapular neck impingement increases the risk of notching and impingement-related instability.

Influence of humeral stem inclination in reverse shoulder arthroplasty on range of motion: a meta-analysis

Hypothesis

The reverse shoulder arthroplasty, as introduced by Grammont, has had many modifications over time. One of these modifications was reducing the neck-shaft angle (NSA) from 155 degrees to 135 degrees. Biomechanical studies indicated that lowering the NSA increases external rotation and reduces abduction and the incidence of scapular notching. The purpose of this study was to compare range of motion, functional outcome measures, and complications in patients undergoing reverse shoulder arthroplasty, depending on the NSA, through a systematic review and meta-analysis.

Methods

A literature search was conducted (articles published from January 1985 to January 2020) in the PubMed/MEDLINE, Embase, and CINAHL databases and the Cochrane library. All studies reporting outcomes after primary reverse shoulder arthroplasty for osteoarthritis and rotator cuff-related disease were included. Patients were divided into 2 groups: a medialized design (MD) with an NSA of 150-155 degrees and a lateralized design (LD) with an NSA of less than 150 degrees. Pooled effects were calculated in the form of mean differences and 95% confidence intervals (CIs). Risk of bias was assessed using the Risk Of Bias In Non-Randomized Studies - of Interventions tool for non-Randomized Controlled Trials and the Risk Of Bias 2 tool for Randomized Controlled Trials.

Results

A total of 21 studies and 3134 arthroplasties were included: 1366 with an MD and 1678 with an LD. The mean age was 73.0 years (MD 74.0 and LD 72.5). A direct comparative meta-analysis was not feasible, and therefore, all data were compared using the minimal clinically important difference. The MD group demonstrated a larger improvement in abduction (56.76°, 95% CI 37.03-76.49) than the LD group (48.52°, 95% CI 28.27-68.78), however the LD group demonstrated a larger improvement in external rotation with the arm at the side (MD: 7.69°, 95% CI 0.01-15.37; LD: 16.14° 95% CI 7.18-25.09). When looking at the postoperative range of motion, the MD group had more abduction than the LD group (MD: 136.28°, 95% CI 127.36-145.20; LD: 127.77° 95% CI 117.02-138.52). Both designs had a comparable improvement in the Constant Murley score (MD 42.04 points, LD 41.14 points). Lowering the NSA was accompanied by a decrease in dislocation rate (MD: 4.6%; LD: 1.4%; P value .037) and notching rate (MD: 40.3%; LD: 17.3%; P value <.0001).

Conclusion

In our analysis, lowering the NSA decreases the amount of abduction but increases the amount of external rotation. This change in range of motion is accompanied by less scapular notching and dislocations. There is no clear impact on functional outcome measures.

Larger polyethylene glenospheres in reverse shoulder arthroplasty: are they safe?

Background

Reverse shoulder arthroplasty is gaining popularity owing to its proven longevity and good outcome scores. Scapular notching remains a concern. This study aimed to assess the safety of larger polyethylene glenospheres with increased eccentricity in comparison with the more conventional metal bearings. The secondary effects on scapular notching, clinical outcomes, range of movement, and complications were also analyzed.

Methods

We conducted a 10-year retrospective review of 145 SMR reverse shoulder arthroplasties (LimaCorporate, Udine, Italy) in 132 patients with radiographs at a minimum of 2 years postoperatively. The primary outcome measure was the survivorship of the larger polyethylene glenospheres. Secondary outcomes were the presence and size of notching, subjective satisfaction score, American Shoulder and Elbow Surgeons score, Oxford Shoulder Score, range of motion, and shoulder-related complications.

Results

No failures of the polyethylene glenospheres were noted in the 10-year period. At a minimum of 2 years’ follow-up, notching was noted in 16 (25%) of the metal glenospheres vs. 9 (11.1%) of the polyethylene glenospheres (P = .028). The mean Oxford Shoulder Score was lower for the metal glenospheres (P = .005). Range of motion, complications, and overall satisfaction were similar in both groups.

Conclusion

The inverted bearing configuration demonstrated no failures at a minimum of 2 years’ follow-up. A larger study is required to determine whether the decreased incidence and size of early notching are related to the bearing size or material.

Effect of scapular notching on clinical outcomes after reverse total shoulder arthroplasty

Aims

Scapular notching is thought to have an adverse effect on the outcome of reverse total shoulder arthroplasty (RTSA). However, the matter is still controversial. The aim of this study was to determine the clinical impact of scapular notching on outcomes after RTSA.

Methods

Three electronic databases (PubMed, Cochrane Database, and EMBASE) were searched for studies which evaluated the influence of scapular notching on clinical outcome after RTSA. The quality of each study was assessed. Functional outcome scores (the Constant-Murley scores (CMS), and the American Shoulder and Elbow Surgeons (ASES) scores), and postoperative range of movement (forward flexion (FF), abduction, and external rotation (ER)) were extracted and subjected to meta-analysis. Effect sizes were expressed as weighted mean differences (WMD).

Results

In all, 11 studies (two level III and nine level IV) were included in the meta-analysis. All analyzed variables indicated that scapular notching has a negative effect on the outcome of RTSA . Statistical significance was found for the CMS (WMD –3.11; 95% confidence interval (CI) –4.98 to –1.23), the ASES score (WMD –6.50; 95% CI –10.80 to –2.19), FF (WMD –6.3°; 95% CI –9.9° to –2.6°), and abduction (WMD –9.4°; 95% CI –17.8° to –1.0°), but not for ER (WMD –0.6°; 95% CI –3.7° to 2.5°).

Conclusion

The current literature suggests that patients with scapular notching after RTSA have significantly worse results when evaluated by the CMS, ASES score, and range of movement in flexion and abduction.

Cite this article: Bone Joint J 2020;102-B(11):1438–1445.

Bony increased-offset-reverse shoulder arthroplasty: 5 to 10 years' follow-up

BACKGROUND

Glenoid lateralization has been shown to be the most imortant factor in maximizing passive range of motion and shoulder stability while preventing scapular impingement and notching. We aimed to evaluate mid- to long-term functional and radiologic outcomes after bony increased-offset-reverse shoulder arthroplasty (BIO-RSA) using a Grammont-style (medialized) humeral implant.

METHODS

The study included 143 consecutive shoulders (140 patients; mean age, 72 years) treated with a BIO-RSA for rotator cuff deficiency. A cylinder of autologous cancellous bone graft, harvested from the humeral head, was placed between the reamed glenoid surface and baseplate; fixation was achieved using a long central peg (25 mm) and 4 screws. A large baseplate (29 mm) with a small baseplate sphere (36 mm) was used in 77% of cases, and a Grammont-style (medialized) humeral implant with 155° of inclination was used in all cases. All patients underwent clinical and radiographic assessment at a minimum of 5 years after surgery; in addition, 86 cases (60%) underwent computed tomography scan assessment.

RESULTS

At a mean follow-up of 75 months (range, 60-126 months), the survivorship of the BIO-RSA using revision as an endpoint was 96%. No cases of dislocation or humeral loosening were observed. Overall, 118 patients (83%) were either very satisfied (61%) or satisfied (22%). The adjusted Constant score improved from 40% ± 18% to 93% ± 23%, and the Subjective Shoulder Value improved from 31% ± 15% to 77% ± 18% (P < .001). The humeral bone graft incorporated completely in 96% of cases (137 of 143). Severe inferior scapular notching (grade 3 or 4) occurred in 18% (24 of 136). The risk of postoperative notching correlated to a lower body mass index (P < .05), superior glenosphere inclination (P = .02), and high or flush glenosphere positioning (P = .035).

CONCLUSIONS

BIO-RSA is a safe and effective technique to lateralize the glenoid, providing consistent bone graft healing, excellent functional outcomes, a low revision rate, and a high rate of patient satisfaction. Thin patients (with a low body mass index) and glenosphere malposition (with persistent superior inclination and/or insufficient lowering of the baseplate and sphere) are associated with higher risk of scapular notching.Our data confirm the importance of implanting the baseplate with a neutral inclination (reverse shoulder arthroplasty angle < 5°) and with sufficient glenosphere inferior overhang (>5 mm) in preventing scapular notching. The use of a less medialized humeral implant (135° or 145° inclined) and smaller (25-mm) baseplate (when using a small, 36-mm sphere) should allow reduction in the incidence of scapular notching.

The modern reverse shoulder arthroplasty and an updated systematic review for each complication: part I

Background

Globally, reverse shoulder arthroplasty (RSA) has moved away from the Grammont design to modern prosthesis designs. The purpose of this 2-part study was to systematically review each of the most common complications of RSA, limiting each search to publications in 2010 or later. In this part (part I), we examined (1) scapular notching (SN), (2) periprosthetic infection (PJI), (3) mechanical failure (glenoid or humeral component), and (4) neurologic injury (NI).

Methods

Four separate PubMed database searches were performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Overall, 113 studies on SN, 62 on PJI, 34 on mechanical failure, and 48 on NI were included in our reviews. Univariate analysis was performed with the χ² or Fisher exact test.

Results

The Grammont design had a higher SN rate vs. all other designs combined (42.5% vs. 12.3%, P < .001). The onlay humeral design had a lower rate than the lateralized glenoid design (10.5% vs. 14.8%, P < .001). The PJI rate was 2.4% for primary RSA and 2.6% for revision RSA. The incidence of glenoid and humeral component loosening was 2.3% and 1.4%, respectively. The Grammont design had an increased NI rate vs. all other designs combined (0.9% vs. 0.1%, P = .04).

Conclusions

Focused systematic reviews of the recent literature with a large volume of RSAs demonstrate that with the use of non-Grammont modern prosthesis designs, complications including SN, PJI, glenoid component loosening, and NI are significantly reduced compared with previous studies. As the indications for RSA continue to expand, it is imperative to accurately track the rates and types of complications to justify its cost and increased indications.

Midterm clinical and radiologic results of reverse shoulder arthroplasty with an eccentric glenosphere

BACKGROUND

An eccentric glenosphere (EG) has been proposed as a way of preventing scapular notching after reverse shoulder arthroplasty (RSA). Our aim was to report the midterm clinical and radiographic results of EG after RSA. A number of the patients described here were included in a previous study with short-term follow-up. The current retrospective study gave us the opportunity to follow many of these patients for a longer period of time.

METHODS

A retrospective analysis of prospectively collected data was conducted. Statistical significance was set at P < .001. Forty-nine RSAs with an EG and at least 60 months of follow-up were included. Range of motion (ROM), Constant scores (CSs), and Subjective Shoulder Value (SSV) were assessed. Scapular notching was graded according to the Sirveaux classification.

RESULTS

At the last follow-up, the mean improvement in active elevation (ROM) was 46° and the mean CS increased by nearly 31 points (both groups P < .001). The final SSV was 70%. Twenty-one patients (43%) had scapular notching, but in two-thirds of patients it was low-grade.

CONCLUSION

The use of an EG provided excellent clinical outcomes that persisted with midterm follow-up. The rate of notching was lower than in other studies with EGs, but further studies are required to confirm this. An EG was safe and there were no issues with baseplate loosening or failure.

The influence of glenoid component position on scapular notching: a detailed radiographic analysis at midterm follow-up

Background

Glenoid baseplate and glenosphere positioning may affect scapular notching rates. The purpose of this study was to assess various radiographic parameters and correlate them with scapular notching after primary reverse total shoulder arthroplasty (RTSA) at a minimum follow-up time of 5 years.

Methods

The study sample included 147 primary RTSA with good-quality postoperative radiographs at least 5 years after implantation (mean follow-up 6.1 years, range 5-12 years). The center of rotation (COR) of the glenosphere in reference to the bone-baseplate interface was medialized in 71 and lateralized in 76 shoulders, with a varus polyethylene opening angle in 134 shoulders. Preoperative and immediate postoperative radiographs were measured to determine (1) glenoid baseplate inclination: α, β, and the reverse shoulder arthroplasty (RSA) angles; (2) glenoid component inferiorization—peg glenoid rim distance (PGRD); and (3) sphere bone overhang distance (SBOD). Scapular notching was graded according to the Sirveaux classification.

Results

Scapular notching was noted in 98 shoulders (67%) and classified as grade 1 in 46, grade 2 in 25, grade 3 in 20, and grade 4 in 7. There were statistically significant associations between notching and both medialized glenospheres (91% vs. 45%, P = .001) and varus polyethylene angle (P = .0001). The mean postoperative RSA angle, PGRD, and SBOD were 6.6 degrees, 23.8 mm, and +2.6 mm, respectively. Preoperative α and postoperative β, RSA, PGRD, and SBOD were all associated with notching (P < .05). The rate of reoperation was 2.7% at a minimum of 5 years, with reasons for reoperation related to component failure in only one shoulder.

Conclusion

Scapular notching correlates with glenoid and baseplate inclination, baseplate inferiorization, inferior glenosphere overhang, glenosphere COR, humeral polyethylene angle, and longer clinical follow-up. SBOD is a clinically useful measurement with decreased values associated with notching. It is the superior measurement in implants with eccentric glenospheres. Moderate or severe notching was seen in only approximately 15% of the shoulders. Revision surgery was extremely low in this cohort, and it was not related to notching or instability.

Can a functional difference be detected in reverse arthroplasty with 135° versus 155° prosthesis for the treatment of rotator cuff arthropathy: a prospective randomized study

BACKGROUND

The purpose of this randomized controlled trial was to compare humeral inclinations of 135° and 155° in patients undergoing primary reverse shoulder arthroplasty (RSA). Our hypothesis was that forward flexion would be higher in the 155° group but be associated with a higher rate of scapular notching.

METHODS

A randomized controlled trial was conducted on 100 primary RSAs performed with a humeral inclination of either 135° or 155°. The prostheses were otherwise identical and a neutral glenosphere was used in all cases. Functional outcome, forward flexion, external rotation, and scapular notching were assessed at a minimum of 2 years postoperatively.

RESULTS

There was no difference in range of motion or functional outcome scores between the 2 groups. In the 155° group, forward flexion improved from 76° to 135° (P < .001) and external rotation remained unchanged (29° vs. 30°; P = .835). In the 135° group, postoperative forward flexion improved from 78° to 132° (P < .001) and external rotation was unchanged (28° vs. 29°; P = .814). Scapular notching was observed in 58% of cases with a 155° inclination compared with 21% with a 135° inclination (P = .009).

CONCLUSION

With a neutral glenosphere there was no difference in postoperative forward flexion or external rotation after an RSA with a humeral inclination of 135° compared with 155°. Scapular notching was reduced with the use of 135° design compared with a 155° design but persists at a rate of 21% at 2-year follow-up in the absence of a lateralized glenosphere.

Outcomes of reverse shoulder arthroplasty in small- and large-stature patients

BACKGROUND

As the worldwide use of reverse shoulder arthroplasty (RSA) increases, a range of implant sizes may be required to match regional and ethnic variation in patients' stature. Size-mismatched implants may possibly result in poorer surgical outcomes. The purpose of this study was to compare the outcomes of primary RSA in patients at the extreme ends of the growth curve with those in average-stature patients in the United States.

METHODS

A multicenter shoulder arthroplasty database was retrospectively reviewed to identify all primary RSAs using a single implant system with a minimum 2-year follow-up. Small patients were defined as the height of <155 cm, tall as >183 cm, and average as 162-178 cm. Active range of motion (ROM), visual analog scale pain score, and patient-reported outcomes (PROs) were compared among the 3 groups.

RESULTS

The study included 552 shoulders (130 small, 384 average, and 38 tall stature). Preoperatively, the average height group had significantly less ROM than the other groups, but there were no significant differences in postoperative ROM. This resulted in poorer improvements in postoperative ROM in the small and tall groups, with the small-stature patients having significantly less ROM improvement compared with average-stature patients. However, these differences did not result in poorer PROs between groups.

DISCUSSION

Small- and large-stature patients showed inferior improvements in ROM after RSA compared with average-stature patients. Our results suggest that current implants optimize ROM gains for average-stature patients and improve PROs independently of patient stature at a minimum 2-year follow-up.

The effect of glenoid component version and humeral polyethylene liner rotation on subluxation and impingement in reverse shoulder arthroplasty

BACKGROUND

A previously validated finite element modeling approach was used to determine how changes in glenoid component version and polyethylene liner rotation within the humeral component affect the arm abduction angle at which impingement between the inferior glenoid and the polyethylene liner occurs as well as the amount of subluxation generated by that impingement.

MATERIALS AND METHODS

Five glenoid component versions (5° anteversion; neutral; 5°, 10°, and 20° retroversion) and 7 polyethylene liner rotations (20° and 10° anterior; neutral; 10°, 20°, 30°, and 40° posterior) were considered, resulting in 35 different clinically representative models. The humerus was internally and externally rotated and extended and flexed, and the resulting impingement and subluxation were measured. To further analyze more global trends and to identify implantations least prone to subluxation, polyethylene liner rotation was additionally varied in coarser 30° increments across the entire 360° range.

RESULTS

All subluxation caused by impingement occurred during external rotation and extension, and external rotation produced nearly 10-fold more subluxation than extension. Neutral glenoid component version was associated with the least amount of subluxation for all polyethylene liner rotations. Posteriorly rotated polyethylene liners, which place the thick inferior region of the component away from the scapula, produced the least amount of subluxation. The 90° and 120° posterior liner rotations produced no subluxation, whereas the 30° and 60° anterior liner rotations produced the greatest amount of subluxation.

CONCLUSION

These results indicate that rotating modern radially asymmetric humeral polyethylene liners posteriorly can reduce the risk of subluxation leading to dislocation and increase external rotation range of motion.

Reverse shoulder arthroplasty patient personalized rehabilitation protocol. Preliminary results according to prognostic groups

Background

Rehabilitation after Reverse Shoulder Arthroplasty (RSA) is still object of discussion with no based evidence guidelines. The aim of this study was to test a personalized rehabilitation protocol for three different patients groups according to clinical and intraoperative parameters that can affect final outcomes after RSA.

Patients and methods

We retrospectively evaluated a consecutive series of 112 patients who underwent to RSA between 2013 and 2015. The average follow-up was 29.2 months. A preoperative and postoperative clinical and radiographic assessment was performed. According to clinical, radiographic and intraoperative parameters, we selected three groups dedicating each one a specific level of post surgical care.

Results

A statistically significant improvement was achieved from preoperative evaluation, regarding all analysed parameters. Notable improvements were reported in high care group: elevation improved of 63.9° despite of Group A 55.5° and Group B 54.5° and it resulted statistically significant (p< 0.05). Costant Score increased of 35.9%, despite of Group A and Group B respectively 40.6% and 34.8% (p> 0.05).

Conclusion

Our study shows that a personalized rehabilitation protocol can be effective improving clinical outcomes and decreasing complications rate, particularly in difficult management patients.

Level of Evidence

Therapeutic Level IV.

Analysis of polyethylene wear of reverse shoulder components: A validated technique and initial clinical results

One of the most prevalent phenomena associated with reverse total shoulder arthroplasty (rTSA) is scapular notching. Current methods examine only the damage to the scapula and no methods are available for quantifying the total wear volume of the polyethylene humeral bearing. Quantifying the polyethylene material loss may provide insight into the mechanism for scapular notching and into the particle dose delivered to the patient. A coordinate measurement machine (CMM) and custom computer algorithms were employed to quantify the volumetric wear of polyethylene humeral bearings. This technique was validated using two never-implanted polyethylene humeral liners with a controlled amount of wear in clinically relevant locations. The technique was determined to be accurate to within 10% of the known value and within 5 mm³ of the gravimetrically determined values. Following validation, ten retrieved polyethylene humeral liners were analyzed to determine a baseline for future clinical tests. Four of the ten polyethylene humeral liners showed visible and measureable wear volumes ranging from 40 to 90 mm³ total with a maximum wear rate as high as 470 mm³ /year in one short duration and significantly damaged humeral liner. This validated technique has the potential to relate patient outcomes such as scapular notching grades to polyethylene release into the body. While the total wear volumes are less than reported in literature for cases of osteolysis in knee and hip patients, dosages are well within the osteolytic thresholds that have been suggested, indicating that osteolysis may be a clinical concern in the shoulder. This work provides the basis for future studies that relate volumetric wear to patient outcomes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:980-987, 2017.

Influence of glenosphere size on the development of scapular notching: a prospective randomized study

HYPOTHESIS

The objective of the study was to evaluate the development of scapular notching in reverse shoulder arthroplasty by comparing larger glenospheres (42 mm) with smaller glenospheres (38 mm).

METHODS

This was a prospective randomized study of 81 patients who had undergone reverse shoulder arthroplasty with a 2-year follow-up. Patients were randomized to receive either a 42-mm glenosphere (38 patients) or a 38-mm glenosphere (43 patients). Scapular notching development was assessed with an anteroposterior radiograph at the end of the follow-up. Functional outcome was assessed with the Constant score before surgery and at the end of follow-up. An independent blinded observer carried out radiologic and clinical assessments.

RESULTS

Scapular notching was present in 48.8% of the patients receiving a 38-mm glenosphere and in 12.1% of the patients receiving one of 42 mm, with significant differences between both (P < .001). No significant differences were noted between the 2 glenosphere size groups in terms of the total Constant score. Patients with a 42-mm glenosphere had a mean glenoid-glenosphere overhang of 6.1 mm, whereas patients with a 38-mm glenosphere had one of 4.2 mm, with significant differences between them (P < .001). No significant differences in the total Constant score were found between the patients whether they had scapular notching or not.

CONCLUSION

Bigger glenospheres (42 mm) significantly reduce development of scapular notching compared with smaller glenospheres (38 mm). Glenosphere size has no significant influence on functional outcomes measured with the Constant score.

Elucidating trends in revision reverse total shoulder arthroplasty procedures: a retrieval study evaluating clinical, radiographic, and functional outcomes data

BACKGROUND

The purpose of this study was to explore relationships between damage modes in explanted reverse total shoulder arthroplasty (RTSA) components, patient and radiographic risk factors, and functional data to elucidate trends in RTSA failure.

METHODS

Fifty RTSA systems, retrieved from 44 patients, with 50 polyethylene (PE) liners, 30 glenospheres, 21 glenoid baseplates, 13 modular humeral metaphases, and 17 humeral stems, were examined for damage modes, including abrasion, burnishing, dishing, embedding, scratching, and pitting. PE liners were also analyzed for delamination and edge deformation. Charts were reviewed for patient, surgical, and functional data. Pre-revision radiographs were analyzed for scapular notching and loosening.

RESULTS

Average term of implantation was 20 months (range, 0-81 months). Metallic components exhibited abrasion, burnishing, dishing, pitting, and scratching. PE liners displayed all damage modes. Damage was exhibited on 93% of glenospheres and 100% of PE liners. Of 29 aseptic shoulders, 13 showed evidence of scapular notching and 5 of humeral loosening. There was a moderate correlation between radiographically observed implant failure or dissociation and PE embedding (r = 0.496; P < .001). There were weak and moderate correlations between scapular notching severity and PE dishing (r = 0.496; P = .006), embedding (r = 0.468; P = .010), and delamination (r = 0.384; P = .040).

CONCLUSIONS

To date, this is the largest series of retrieved RTSA components and the first to relate damage modes to radiographic and clinical data. Most damage was observed on the PE liners, on both the articular surface and rim, and glenosphere components. Correlation of retrieval findings with radiographic and clinical data may help establish predictors of prostheses at risk for failure.

Mechanical tradeoffs associated with glenosphere lateralization in reverse shoulder arthroplasty

BACKGROUND

Scapular notching in reverse shoulder arthroplasty occurs in up to 97% of patients. Notching is associated with decreased strength and reduced motion and may lead to long-term failure due to polyethylene wear. Many implant systems lateralize the glenosphere to address scapular notching, but the mechanical tradeoffs of lateralization have not been rigorously evaluated. We hypothesized that lateralization would decrease bony impingement but also decrease the mechanical advantage of the deltoid.

METHODS

Finite element models were created using the same implants with different amounts of glenoid lateralization: 5 mm of medialization to replicate glenoid erosion, as well as 2.5, 5, 7.5, and 10 mm of lateralization. Tests were performed with static and dynamic scapulae for motion in either the coronal or scapular plane. The angle of impingement between the scapula and the humeral polyethylene was recorded, as was the deltoid force required to elevate the arm.

RESULTS

Increasing lateralization decreased impingement while increasing the deltoid force required to elevate the arm. Differences were found between the static and dynamic scapulae, with the dynamic scapula model having increased humeral adduction before impinging. The impingement angle was also substantially affected by the bony prominences on the inferior scapula, showing how individual bony anatomy can affect impingement.

CONCLUSION

Lateralization is effective in increasing impingement-free range of motion but also increases the deltoid force required to perform identical tasks. In addition, impingement is determined by scapular motion, which should be included in all shoulder models.

Effect of implant geometry on range of motion in reverse shoulder arthroplasty assessed using glenohumeral separation distance

BACKGROUND

Whereas reverse shoulder arthroplasty has been successful in treating patients with cuff tear arthropathy, implant impingement after the procedure often causes complications, including reduced range of motion, bone loss, and instability. Attempts to simulate this problem in vitro typically rely on subjective visual methods to detect impingement. The purpose of this study was to determine the effect of humeral neck-shaft angle, implant diameter, humeral cup depth, and glenoid component eccentricity on minimum abduction angle and range of motion using an implant-tracking method for impingement detection.

METHODS

Tests were performed in a kinematic shoulder simulator with actuated cables representing the deltoid. The humerus was manually adducted and abducted past the point of impingement in either direction. Centers of the implant components were tracked with optical motion capture and processed with a thresholding algorithm to determine the minimum abduction angle where impingement occurred.

RESULTS

Humeral cup depth had the largest effect on minimum abduction angle and range of motion, with a retentive cup reducing range of motion by 26°. A decreased neck-shaft angle reduced minimum abduction angle by 10° but had little effect on overall range of motion. Diameter and eccentricity had little effect.

CONCLUSION

A reduced neck-shaft angle reduces minimum abduction angle but does not improve overall range of motion. A more retentive humeral cup increases minimum abduction angle significantly. Although retentive cups are intended to improve joint stability, the reduced range of motion that they impart to the joint may partly counteract the benefits of increased constraint.

Does bony increased-offset reverse shoulder arthroplasty decrease scapular notching?

BACKGROUND

The purpose of this cohort study was to compare scapular notching rates, range of motion, and functional outcomes between patients who underwent a standard Grammont-style reverse shoulder arthroplasty (RSA) and patients who underwent bony increased-offset reverse shoulder arthroplasty (BIO-RSA) at a minimum of 2 years' follow-up. We hypothesized that the BIO-RSA cohort would have lower notching rates and improved rotational range of motion; however, validated outcome scores between cohorts would be no different.

METHODS

A comparative cohort study was designed after a sample size calculation. A total of 40 patients were studied with 20 in each cohort (RSA vs BIO-RSA). All patients underwent an interview and physical examination. Outcomes included range of motion; shoulder strength; Disabilities of the Arm, Shoulder and Hand (DASH) score; American Shoulder and Elbow Surgeons score; Simple Shoulder Test score; Constant score; and Global Rating of Change scale score. Radiographs were obtained for all patients and examined for scapular notching.

RESULTS

When we compared demographic characteristics between the standard RSA and BIO-RSA cohorts, including age, sex, and follow-up duration, there were no significant differences between groups (P > .05). In addition, there were no significant differences between cohorts when we compared forward elevation (P = .418); external rotation (P = .999); internal rotation (P = .071); strength (P > .376); Disabilities of the Arm, Shoulder and Hand score (P = .229); American Shoulder and Elbow Surgeons score (P = .579); Simple Shoulder Test score (P = .522); Constant score (P = .917); or Global Rating of Change scale score (P = .167). The frequency of scapular notching, however, was significantly higher (P = .022) in the RSA cohort than in the BIO-RSA cohort: 75% versus 40%.

CONCLUSIONS

Although the scapular notching rate was significantly higher in the standard RSA group, no other outcome measures were statistically different, including range of motion, strength, and validated outcome scores.

Biomechanics of reverse total shoulder arthroplasty

Reverse total shoulder arthroplasty is an effective procedure for treatment of glenohumeral joint disease among patients with severe rotator cuff deficiency. Improvements in prosthetic design are the result of an evolved understanding of both shoulder and joint replacement biomechanics. Although modern generations of the reverse shoulder prosthesis vary in specific design details, they continue to adhere to Grammont's core principles demonstrated by his original Delta III prosthesis. This review article discusses the biomechanics of reverse total shoulder arthroplasty with a focus on elements of implant design and surgical technique that may affect stability, postoperative complications, and functional outcomes.

Wear rates of highly cross-linked polyethylene humeral liners subjected to alternating cycles of glenohumeral flexion and abduction

BACKGROUND

Although short-term outcomes of reverse total shoulder arthroplasty have been promising, long-term success may be limited due to device-specific complications, including scapular notching. Scapular notching has been explained primarily as mechanical erosion; however, the generation of wear debris may lead to further biologic changes contributing to the severity of scapular notching.

METHODS

A 12-station hip simulator was converted to a reverse total shoulder arthroplasty wear simulator subjecting conventional and highly cross-linked ultra-high-molecular-weight polyethylene humeral liners to 5 million cycles of alternating abduction-adduction and flexion-extension loading profiles.

RESULTS

Highly cross-linked polyethylene liners (36.5 ± 10.0 mm(3)/million cycle) exhibited significantly lower volumetric wear rates compared with conventional polyethylene liners (83.6 ± 20.6 mm(3)/million cycle; P < .001). The flexion-extension loading profile exhibited significantly higher wear rates for conventional (P < .001) and highly cross-linked polyethylene (P < .001) compared with the abduction-adduction loading profile. Highly cross-linked wear particles had an equivalent circle diameter significantly smaller than wear particles from conventional polyethylene (P < .001).

CONCLUSIONS

Highly cross-linked polyethylene liners significantly reduced polyethylene wear and subsequent particle generation. More favorable wear properties with the use of highly cross-linked polyethylene may lead to increased device longevity and fewer complications but must be weighed against the effect of reduced mechanical properties.

The TESS reverse shoulder arthroplasty without a stem in the treatment of cuff-deficient shoulder conditions: clinical and radiographic results

BACKGROUND

Reverse total shoulder arthroplasty (RSA) is a recent concept that enables good functional outcomes in cases of massive rotator cuff tear and cuff tear arthropathy. Design parameters influence the functional results and complications. The purpose of this study is to present the results of a novel RSA, the Total Evolutive Shoulder System (TESS; Biomet, Warsaw, IN, USA), based on a reverse corolla without a stem.

METHODS

We enrolled 101 patients with 105 RSAs in a prospective study, with a minimum follow-up period of 24 months. The analysis concerned 91 RSAs in 87 patients (61 men and 26 women), with a mean age of 73 years, at a mean follow-up of 41 months (range, 24-69 months).

RESULTS

Ninety-six percent of patients rated their satisfaction as good or excellent. Mean flexion was 143° (range, 90°-170°), and mean external rotation was 39° (range, 20°-70°). The Constant score improved from 40 points preoperatively to 68 points at last follow-up (P < .001). The mean American Shoulder and Elbow Surgeons score was 24 points. The mean neck-shaft angle was 154° (range, 142°-165°). Inferior scapular notching occurred in 17 cases (19%). The notching rate was higher when the glenometaphyseal angle increased (P < .001), when the inferior tilt decreased (P = .003), and when the neck-shaft angle increased. There was no evidence of component loosening.

CONCLUSION

TESS RSA provided encouraging midterm results with favorable outcomes and a low rate of complications. The stemless TESS with a reverse corolla is a reliable, less invasive system.

Reversed shoulder arthroplasty with inversed bearing materials: 2-year clinical and radiographic results in 101 patients

INTRODUCTION

This study documents 2-year clinical and radiographic results following reversed total shoulder arthroplasty using a novel prosthesis with inverted bearing materials (polyethylene glenoid; metal humeral component). This design was intended to avoid massive PE abrasion on the humeral side. Therefore, we predicted a lack of subsequent osteolysis-induced exacerbation of scapular notching, and because of other design features and modified operating technique a reduced notching rate.

MATERIALS AND METHODS

An ongoing, prospective, international, multicenter study of patients implanted with a novel prosthesis at six European centers. The current analysis presents 2-year follow-up data (patients operated between December 2007 and July 2009). Clinical evaluation tools comprised the Constant-Murley score (CS), the American Shoulder and Elbow Surgeon score, range of motion, and a visual analog scale to assess pain and satisfaction. Radiographs were evaluated for notching and radiolucent lines. Any complications were recorded.

RESULTS

In total, 113 prostheses (113 patients) with a mean follow-up of 27.6 (±3.6) months were analyzed. CS increased from 22.5 (±13.7) to 65.3 (±14.9) points (p = 0.06). Inferior scapular notching (only grade 1 and 2) was identified in 20.5 % of patients, with no signs of PE-induced osteolysis. 4.4 % of patients experienced an implant-related complication.

CONCLUSIONS

Inversion of the materials led to another type of notching with no signs of PE-induced osteolysis and no increase in the risk of short-term complications. Clinical results were comparable with other prostheses. Mid- to long-term results are required before any firm conclusions on clinical outcome and survival can be drawn.

Decreased scapular notching with lateralization and inferior baseplate placement in reverse shoulder arthroplasty with high humeral inclination

Background:

Scapular notching is a radiographic finding of unknown clinical significance following reverse total shoulder arthroplasty (RTSA). The purpose of this study was to determine how baseplate position affects the incidence of scapular notching and measure the clinical outcomes.

Hypothesis:

We hypothesized that low base plate position on the glenoid and new prosthesis design with a higher humeral inclination angle would decrease the incidence of notching at 2 years follow-up.

Materials and methods:

A total of 54 patients with an average follow-up of 30 months met inclusion criteria and underwent radiographic analysis of scapular notching and radiographic measures to determine glenoid component placement. Clinical measures including visual analog score, American Shoulder and Elbow Surgeons (ASES) scores, and range of motion (ROM) were prospectively collected.

Results:

Thirty-nine of the 54 patients had no notching. 7 had Grade 1 notching, 7 had Grade 2 notching, one had Grade 3, and one had Grade 4 notching. Notching was associated with higher placement of the glenoid component as measured by peg-glenoid rim distance and base plate distance. All patients with no evidence of notching at 1-year, continued to have no notching after multi-year follow-up. Clinical outcome measures including ASES scores, ROM, and visual analog pain scores were improved at follow-up.

Conclusion:

We concluded that lower neck-shaft angle and low baseplate positioning led to a low incidence of significant scapular notching as only 6 out of 57 (16%) patients had notching Grade 2 and above. At short-term follow-up, this RTSA results in excellent clinical outcomes and a significantly lower scapular notching rate than traditional techniques.

Influence of glenosphere design and material on clinical outcomes of reverse total shoulder arthroplasty

BACKGROUND

The aim of this multicentre retrospective study was to compare reverse total shoulder arthroplasty clinical outcomes with glenospheres of different diameters, designs and materials.

METHODS

Between 2003 and 2008, 133 patients were divided into three groups: 60 (45%) with 36-mm standard CoCrMo (group A), 21 (16%) with 36-mm eccentric cobalt-chromium-molybdenum (CoCrMo) (group B) and 52 (39%) with 44-mm cross-linked ultra-high molecular weight polyethylene (X-UHMWPE) (group C) glenospheres. Mean (SD) follow-up was 38.7 (17.4) months. Clinical evaluation included Constant score and range of motion. Radiographic analysis included radiolucent lines, instability, loosening and assessment of scapular notching.

RESULTS

Mean Constant score significantly increased for all groups (Wilcoxon test, p < 0.001). Group C allowed a higher and stable increase in range of motion. After 12 months and 24 months, groups C and B showed less pain than group A (Mann-Whitney U-test, p < 0.05). Group C had significantly lower scapular notching than group B (Mann-Whitney U-test, p = 0.001) and A (Mann-Whitney U-test, p = 0.009) at 12 months, 24 months and 36 months. Groups A and C presented 5 (8.3%) and 4 (7.6%) early complications, respectively.

CONCLUSIONS

The present study reported good results for all groups, although groups C and A presented better clinical outcomes, significantly lower notching and instability. A 44-mm X-UHMWPE glenosphere allowed a faster and more stable functional recovery, despite poorest pre-operative conditions. Additional long-term studies are needed to evaluate survivorship.

Evaluation of the role of glenosphere design and humeral component retroversion in avoiding scapular notching during reverse shoulder arthroplasty

BACKGROUND

Scapular notching is a common observation during radiological follow-up of reverse shoulder arthroplasty. The purpose of this study was to evaluate the effect of glenosphere design and humeral component retroversion on movement amplitude in the scapular plane and inferior scapular impingement.

MATERIALS AND METHODS

The Aequalis Reversed Shoulder Prosthesis (Tornier) was implanted into 40 cadaver shoulders. On the glenoid side, 8 different combinations were tested: 36-mm glenosphere: centered (standard), eccentric, with an inferior tilt, or with the center of rotation (COR) lateralized by 5 or 7 mm; and 42-mm centered glenosphere: used alone or with the COR lateralized by 7 or 10 mm. The humeral component was positioned in 0°, 10°, 20°, 30°, and 40° of retroversion. Maximum adduction and abduction were measured when inferior impingement and superior impingement, respectively, were detected.

RESULTS

The average increase in abduction amplitude was 10° and inferior impingement occurred 18° later with a 42-mm glenosphere, especially when it was lateralized by 10 mm, relative to a 36-mm centered glenosphere (P < .05). These 2 combinations provided a 28° increase in the movement amplitude in the scapular plane. Positioning of the humeral component in 10° or 20° of retroversion or in anatomical retroversion was most effective at avoiding inferior impingement but had less effect on abduction range of motion (except with the 42-mm glenosphere).

CONCLUSION

Our study confirmed published results with various glenosphere designs but was unique in describing the effect of humeral retroversion on scapular impingement. Inferior scapular notching can be most effectively prevented by using large-diameter glenospheres with lateralized COR and by making sure to replicate the patient's native humeral retroversion.

Polyethylene wear in retrieved reverse total shoulder components

BACKGROUND

Reverse total shoulder arthroplasty has been used to treat rotator cuff tear arthropathy and proximal humerus fractures, as well as for failed conventional total shoulder prostheses. It has been suggested that polyethylene wear is potentially higher in reverse shoulder replacements than in conventional shoulder replacements. The modes and degree of polyethylene wear have not been completely elucidated. The purpose of this study was to evaluate polyethylene wear patterns in 7 specimens retrieved at revision arthroplasty and identify factors that may be associated with increased wear.

METHODS

Reverse total shoulder components were retrieved from 7 patients during revision arthroplasty for loosening and/or pain. Preoperative glenoid tilt and placement and scapular notching were evaluated by use of preoperative radiographs. Polyethylene wear was evaluated via micro-computed tomography and optical microscopy.

RESULTS

Wear on the rim of the polyethylene humeral cup was identified on all retrieved components. The extent of rim wear varied from a penetration depth of 0.1 to 4.7 mm. We could not show a correlation between scapular notching and rim wear. However, rim wear was more extensive when the inferior screw had made contact with the liner. Metal-on-metal wear between the humeral component and the inferior screw of 1 component was also observed. Wear of the intended bearing surface was minimal.

DISCUSSION

Rim damage was the predominant cause of polyethylene wear in our retrieved specimens. Direct contact between the humeral component and inferior metaglene screws is concerning because this could lead to accelerated ultra-highmolecular weight polyethylene wear and also induce mechanical loosening of the glenoid component.