Patients undergoing reverse total shoulder arthroplasty (rTSA) have been noted on postoperative radiographs to have a curved bony overgrowth on the inferior glenoid neck. This study aims to investigate potential risk factors for and postoperative effects of these ossifications, here called Glenoid HyperOSTosis (GHOST) lesions because of their location.

A retrospective review of patients undergoing rTSA between 2007 and 2020 at a single institution was performed. Predictors, including gender, age, implant sizing, and preoperative diagnosis, were examined using logistic regression analysis. Outcomes including readmission rate, revision rate, preoperative and postoperative range of motion, visual analog scale (VAS) pain scores, and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) functional outcome scores were also analyzed using 2-sample t tests.

Preoperative and postoperative radiographs of 170 primary rTSA patients were assessed. One-fourth (25.9%) of rTSAs were identified to have a GHOST lesion. When adjusting for race, age, body mass index (BMI), and preoperative diagnosis, male patients were still associated with 2.28 odds of developing a GHOST lesion compared with female patients (95% confidence interval [CI] 1.08-4.86). Other elements such as age, race, BMI, laterality, preoperative diagnosis, implant manufacturer, and implant sizing demonstrated no statistically significant association with GHOST lesion presence. Postoperatively, GHOST lesion development was not associated with range of motion or ASES score. However, presence of GHOST lesions on radiographs was associated with increased pain scores for patients at 2 months (P = .034) and 12 months (P = .029) postoperatively.

Inferior GHOST lesions are a common and potentially benign finding following rTSA, with unclear etiology. Risk factors for GHOST lesions included male gender, whereas patient demographics, implant type or size, shoulder lateralization, and distalization were not associated with lesion formation. Clinically, greater short-term VAS scores were seen in patients with GHOST lesions. However, there were no differences observed between the 2 groups in ASES scores or postoperative range of motion at later time points. Further research is needed to identify risk factors and assess the clinical implications of GHOST lesions.

Severe posterior glenoid bone loss with glenohumeral osteoarthritis with an intact rotator cuff can be managed with reverse shoulder arthroplasty but requires lateralization and version correction to avoid potential complications, such as instability, notching and implant failure. Angled bone grafting with humeral head autograft can provide durable glenoid bone stock, but results have been mixed. The purpose of this study was to evaluate patient-reported and objective outcomes as well as complication and failure rates for patients who underwent angled humeral head autografting for severe retroversion.

All patients who underwent a primary reverse shoulder arthroplasty with angled humeral head autograft and Stryker Tornier long central postbaseplate for severe glenoid bone loss in the setting of glenohumeral osteoarthritis with an intact rotator cuff at our institution between November 2018 and February of 2022 were identified. Individuals with a primary diagnosis of osteoarthritis and preoperative glenoid retroversion of ≥30° were included. Patients undergoing revision procedures, planned 2-stage arthroplasty were excluded. Differences in pre- and postoperative range of motion, as well as patient-reported outcomes were assessed. Intraoperative complications, postoperative complications, and re-operation rates were analyzed.

A total of 24 shoulders in 23 patients (61% male), with a mean age of 65.6 years were included. Average preoperative retroversion was 37.4° (range: 30°-51°). Mean follow-up was 2.9 years (range: 2-4.3 years). Significant improvements were found in flexion, abduction, and external rotation. Patient-reported subjective outcomes were excellent, with average American Shoulder and Elbow Surgeons score of 93.6 and average Subjective Shoulder Value score of 93.8%. Sixteen (67%) shoulders received postoperative computed tomography scans and all were found to have incorporated. Complications included one shoulder hematoma requiring incision and drainage without revision, and a post-traumatic fracture of the inferior glenoid screw at 11 months, requiring revision reverse shoulder arthroplasty with bone grafting. No atraumatic catastrophic failures occurred due to component loosening.

This study suggests that using angled humeral head bone grafting is a good solution for version correction in extreme posterior glenoid bone loss. Significant improvements are reported in range of motion, pain, and subjective functional scores, with excellent graft incorporation rates and a low complication profile at early follow-up. Further work should focus on gathering higher levels of evidence, detailed radiographic analyses, and exploring humeral head bone grafting for other indications.

Background: Reverse shoulder arthroplasty (RSA) improves shoulder function in cases of glenohumeral osteoarthritis and rotator cuff arthropathy. The design of the glenosphere influences mobility and scapular impingement. This study evaluates the impact of joint volume on the range of motion (RoM) and identifies design modifications to enhance mobility while reducing the impingement risk. Methods: Thirty-four cadaveric shoulders were implanted with the Aequalis Reversed II® prosthesis in seven configurations: four with 36 mm spheres (centered, 2 mm eccentric, and lateralized by 5 mm and 7 mm) and three with 42 mm spheres (centered, and lateralized by 7 mm and 10 mm). The joint volumes (inferior, anteroinferior, and posteroinferior) were measured via 3D CT scans. The RoM in adduction and elbow-at-side rotations (IR1 and ER1) was recorded. A statistical analysis identified threshold joint volumes correlating with improved mobility. Results: Larger joint volumes correlated with enhanced mobility. The 42 mm spheres demonstrated better adduction and ER1 compared to those of the 36 mm spheres (p < 0.0001). An inferior volume > 5000 mm3 and anteroinferior/posteroinferior volumes >2500 mm3 were thresholds for significant mobility improvement. Lateralization (≥7 mm) or inferior eccentricity (2 mm) improved the mobility with the 36 mm spheres, with the 36 + 2 configuration offering a practical balance for smaller patients. Conclusions: Increased joint volume enhances mobility, particularly in adduction and elbow-at-side rotations. A sphere with a 2 mm inferior offset or a 42 sphere with 7 mm lateralization optimizes the RoM while minimizing impingement risks. Patient-specific considerations, including anatomy and soft tissue tension, remain essential for optimal prosthesis selection.

Radiographic measurements have gained wide acceptance in anticipating the risk of inappropriate glenoid component positioning in reverse shoulder arthroplasty (RSA). This study aims to investigate whether the RSA angle overcorrects the base plate inclination, tilting it inferiorly, compared to the base plate correction angle (BCA), which provides neutral inclination and lateralization.

One hundred normal anteroposterior shoulder radiographs were evaluated to determine the average values of the RSA angle, BCA, base plate orientation angle (BOA), and the base plate shoulder angle (BSA), which represents the amount of overcorrection accomplished via the RSA angle beyond the BCA's scope. The interobserver reliability among two independent testers was assessed by the intraclass correlation coefficient. A t-test was applied to compare the mean values of the BCA and RSA angle.

The mean BOA and BCA values were 118° ± 5.7° and 17° ± 4.6°, respectively. The RSA angle value was 23° ± 6°. Compared to the BCA, the RSA angle overcorrected the base plate inclination by 15° ± 5° (BSA). The Student's t-test showed a statistically significant difference between the values of the BCA and RSA angle (p-value = 0.000). The interobserver reliability was excellent for all angle measurements among two independent testers.

The RSA angle and the BOA/BCA are reliable radiographic measurements to determine the inclination of the inferior glenoid segment prior to RSA. However, surgeons need to consider the inherent inferior inclination associated with positioning the base plate according to the RSA angle (15° ± 5°).

In reverse total arthroplasty (rTSA), glenoid component positioning is a critical factor for outcomes especially in Asian populations with smaller glenoids. The purpose of this study was to compare the clinical and radiologic outcomes of rTSA with and without the navigation system with a minimum follow-up of 2 years in the Asian population.

This was a retrospective comparative study of 33 rTSAs with the navigation system (NAV group) and 40 conventional rTSAs (CON group). Radiologic measurements regarding the position of the glenoid component, glenoid vault perforation by the central cage, and scapular notching, as well as clinical outcomes including range of motion, functional scores, and complications were compared. Number, length, and angulation of screws were assessed.

The mean age was 73.9 ± 5.9 years with a mean follow-up of 30.1 ± 6.4 months. The NAV group more frequently utilized augmented baseplate (P < .001), showed less superior inclination (P = .030) and had lower incidence of glenoid vault perforation (P = .040). The length of superior (P = .001) and inferior screws (P = .045) was longer in the NAV group. In the NAV group compared to the CON group, more inferior orientation of superior screws (P < .001), more anterior orientation for inferior screws (P = .031), and anterior screws (P = .003) were observed. The NAV group showed significantly less penetration into the suprascapular fossa by a superior screw (P = .007). Final range of motion, functional scores, and complications showed no significant differences between the 2 groups.

In the short-term follow-up, the use of a navigation system in rTSA showed no significant difference in clinical outcomes and complications compared to conventional implantation. However, it enabled a lower superior inclination and a reduced glenoid vault perforation by the central cage, simultaneously allowing for the insertion of longer peripheral screws in a safer direction compared to conventional implantation.

The aim of this study is to analyse the most cited articles in shoulder arthroplasty surgery and identify trends in topics by decade.

Journal Citation Index Web of Science (WoS) was searched to find articles using the search terms "shoulder arthroplasty", "shoulder hemiarthroplasty", "shoulder replacement" and "shoulder prosthesis". All articles were ranked according to most cited overall and most cited between 2022 and 2023, and then further analysed to find the most cited articles per decade. Articles were studies for topic, study type, evidence level and number of subjects. A second search was performed using Google Scholar (GS) with the same search terms.

All the most cited articles were published in 4 orthopaedic journals. Citation counts were higher for GS searches than WoS for every article, by an average of 1.92 times. Each decade's most cited articles seemed to fit into a few broad topics, showing trends in that decade. The highest cited papers were generally low-level evidence studies.

Shoulder arthroplasty literature appears to follow trends throughout the decade. High quality evidence is lacking in the highest cited papers, but this study highlights the importance and value of these lower-evidence breakthrough studies, which have shaped shoulder arthroplasty surgery.

Reverse total shoulder arthroplasty (RTSA) is the standard of care for patients with glenohumeral osteoarthritis and rotator cuff deficiency. Preoperative RTSA planning based on medical images and patient-specific instruments has been established over the last decade. This study aims to determine the effects of using augmented reality-assisted intraoperative navigation (ARIN) for baseplate positioning in RTSA compared to preoperative planning. It is hypothesized that ARIN will decrease deviation between preoperative planning and postoperative baseplate positioning. Moreover, ARIN will decrease deviation between the (senior) more (>50 RTSAs/yr) and less experienced (junior) surgeon (5-10 RTSAs/yr).

Preoperative CT scans of 16 fresh-frozen cadaveric shoulders were obtained. Baseplate placements were planned using a validated software. The data were then converted and uploaded to the augmented reality system (NextAR; Medacta International). Each of the 8 RTSAs were implanted by a senior and a junior surgeon, with 4 RTSAs using ARIN and 4 without. A postoperative CT scan was performed in all cases. The scanned scapulae were segmented, and the preoperative scan was laid over the postoperative scapula by the nearest iterative point cloud analysis. The deviation from the planned entry point and trajectory was calculated regarding the inclination, retroversion, medialization (reaming depth) and lateralization, anteroposterior position, and superoinferior position of the baseplate. Data are reported as mean ± standard deviation (SD) or mean and 95% confidence interval (CI). P values < .05 were considered statistically significant.

The use of ARIN yielded a reduction in the absolute difference between planned and obtained inclination from 9° (SD: 4°) to 3° (SD: 2°) (P = .011). Mean difference in planned-obtained inclination between surgeons was 3° in free-hand surgeries (95% CI: -4 to 10; P = .578), whereas this difference reduced to 1° (95% CI: -6 to 7, P = .996) using ARIN. Retroversion, medialization (reaming depth) and lateralization, anteroposterior position, and superoinferior position of the baseplate were not affected by using ARIN. Surgical duration was increased using ARIN for both the senior (10 minutes) and junior (18 minutes) surgeon.

The implementation of ARIN leads to greater accuracy of glenoid component placement, specifically with respect to inclination. Further studies have to verify if this increased accuracy is clinically important. Furthermore, ARIN allows less experienced surgeons to achieve a similar level of accuracy in component placement comparable to more experienced surgeons. However, the potential advantages of ARIN in RTSA are counterbalanced by an increase in operative time.

Inverted-bearing reverse shoulder arthroplasty (IB-RSA) is characterized by a polyethylene glenosphere and a metallic humeral liner to minimize polyethylene wear and debris secondary to impingement between the humerus and glenoid neck. IB-RSA long-term survivorship, complication and revision rates, as well as clinical and radiographic outcomes have not been reported yet.

This is a monocentric retrospective study on a consecutive series of 151 patients who underwent primary IB-RSA from January 2009 to September 2015 and were evaluated clinically and radiologically at the minimum 8-year follow-up. All complications and reoperations were recorded. Survivorship analysis with any revision surgery as endpoint was done using Kaplan-Meier survival curves.

Seventy-eight patients (follow-up rate 51.7%) were reviewed at a mean follow-up of 10.1 ± 1.9 years. At 10 years, the revision-free survival was 98.7% (95% confidence interval: 94.8-99.7). Sixteen complications (10.6%) were observed: 2 axillary nerve injuries, 2 infections, 2 glenoid loosening (which stabilized within 1 year), 2 cases of otherwise unexplained painful stiffness, 4 acromial fractures, 1 post-traumatic scapular pillar fracture, and 3 post-traumatic humeral periprosthetic fractures. Two patients were revised due to infection. No cases of late glenoid loosening and humeral loosening were observed. The revision rate was 1.3%. All the clinical scores and range of motion significantly improved at the last follow-up compared with preoperative status: final Constant score was 66.1 ± 17.4, Subjective Shoulder Value 79.1 ± 20.9, and the American Shoulder and Elbow Surgeons 82.2 ± 17.7. Scapular notching was observed in 51.4% of patients: only 1 case of grade 3 notching was observed in an early glenoid subsidence case.

Primary IB-RSA appears to be a safe and effective procedure and does not present specific implant-associated complications at long-term follow-up. Radiographic analysis showed that inverting the biomaterials leads to a distinct kind of notching with mainly mechanical features.

Friction is the primary cause of notching in reverse shoulder arthroplasty during internal, external rotation (IR/ER), and extension (EXT). To address notching, glenosphere eccentricity (ECC) was introduced. The primary objective of this study was to investigate different positions of glenosphere ECC to determine whether there is an optimal position for impingement-free range of motion.

In this computer model study, 10 female CTs were analyzed and EXT, ER, IR, and adduction simulated (18 models.) A 135° stem with a +10° liner (145°) was combined with a 25-mm standard/or +3-mm lateralized baseplate (BP) and a 36-mm +2-mm eccentric glenosphere in 4 ECC positions (50° posterior; 30° posterior; 30° anterior; 50° anterior) from the reference position 0° neutral (10 models). Additionally, a concentric 39-mm glenosphere was tested (+2 models). A 0° insert, 135° neck shaft angle (NSA), was tested with a 25-mm standard/or +3-mm BP for 3 configurations (30° posterior; neutral; 39 mm; +6 models).

Compared to the 0° neutral reference position, 30° posterior dialing improved the mean ER (group 145°: 40° vs. 38°, group 145° + 3: 51° vs. 49°, both P < .0001), and EXT (group 145°: 35° vs. 34°, P = .029, group 145° + 3: 57° vs. 47°, P = .046, but at the expense of IR (group 145°: 83° vs. 87°, group 145° + 3: 87° vs. 91°, both P < .0001). The position 30° anterior increased IR (group 145°: 90° vs. 87°, group 145° + 3: 94° vs. 91°, both P < .0001) at the expense of ER (group 145°: 33° vs. 38°, group 145° + 3: 44° vs. 49°, both P < .0001) and EXT (group 145°: 24° vs. 34°, P = .055, group 145° +3 mm: 39° vs. 47°, P = .0042). For group 145°, 0° neutral was the best position for combined EXT + IR (121°) compared to 30° posterior/30° anterior/39 mm/50° posterior/50° anterior (118°/113°/118°/113°/110°, P < .0001/P = .15/P = .076/P < .0001/P = .074, respectively) and IR + ER (125° vs. 122°/123°/123°/118°/119°/, P < .001/P = .0028/P = .7/P < .0001/P = .0001, respectively). Lateralization, but most effectively a 135° NSA improved combined EXT + IR + ER + adduction (group 145°: 179° vs. group 135°: 243°, group 145° + 3: 215° vs. group 135° + 3: 276°, P = .0019/P = .00019, respectively). The influence of position 0°neutral or 30°posterior became marginal with a 135°NSA.

Posterior dialing of the ECC increases EXT and ER but at the expense of IR. Lateralization, but most effectively a 135° NSA, increase impingement-free motion. A larger noneccentric glenosphere on the same BP is a safe all-round solution to prevent ECC positioning outliers.

While outcomes following reverse total shoulder arthroplasty (rTSA) have often been gauged through radiological assessments focusing on prosthesis position, there is increasing recognition of patient-reported outcomes, particularly satisfaction, as indicators of surgical success. The objective of this study was to correlate radiological findings with clinical outcomes, patient satisfaction, and health-related quality of life (HRQoL).

A retrospective evaluation was conducted on patients following rTSA at a minimum of 2 years postoperatively. Functional outcome (active range of motion [ROM], Constant Score [CS], American Shoulder and Elbow Surgeons score, and Simple Shoulder Test) and the Short Form-36 were evaluated. Strictly anteroposterior radiographs were used to determine preoperative and postoperative parameters. Preoperative measurements included acromiohumeral interval, reverse shoulder arthroplasty angle, center of rotation (COR), and deltoid length. Postoperatively, the lateralization angle, distalization angle, acromiohumeral distance, peg-glenoid rim distance, sphere-bone overhang distance, reverse shoulder arthroplasty, COR, and deltoid length were measured. Scapular notching was classified according to Sirveaux et al.

A total of 49 patients were evaluated at an average of 30.78 ± 7.15 months postoperatively at last follow-up. Active ROM, pain on the Visual Analog Scale, and CS showed significant improvement (P < .05). There was a high level of patient contentment, which correlated positively with the American Shoulder and Elbow Surgeons score and CS, and negatively with postoperative pain Visual Analog Scale. Postoperative HRQoL, measured by the Short Form-36, showed strong positive correlations with all clinical scores (P < .05). Distalization had a negative impact on external rotation (P = .001) and strength capacity (P = .031). Medialization of the COR showed a contrary relationship to external rotation (P < .001) and strength capacity (P < .001).

This study confirms rTSA's effectiveness in reducing pain and improving daily function, with a high readiness among patients to undergo the surgery again. Patient contentment and HRQoL showed a strong correlation with the clinical outcomes of the surgery. Radiological measurements may predict postoperative ROM and scapular notching yet fail to accurately reflect patient quality of life.

Avoiding inclination of the glenoid baseplate in reverse shoulder arthroplasty often requires considerable glenoid reaming. It is proposed that the use of a metal wedged baseplate in all patients can achieve neutral inclination with reduced glenoid reaming.

A prospective clinical single-centre study with minimum two-year follow-up was carried out. Glenoid deformity was classified on CT and surgery planned using BluePrintTM. The Tornier Perform® Reversed Wedged Augmented Glenoid was used in all cases. Clinical outcome scores and radiographs were assessed.

Seventy-three patients, mean age 76.6 years. Twenty-eight demonstrated no glenoid deformity and 19 demonstrated marked retroversion. Seventy completed two-year follow-up. Mean pain scores fell from 6 to 0.7. All Patient Reported Outcome Meaures (PROMS) were significantly improved. Active elevation increased by 62° and external rotation by 28.7° (p < 0.001). In patients with no glenoid wear (E0/A1), correction of inferior inclination was achievable with a 15° full-wedge baseplate in all cases, reducing the reaming depth by 4.4 mm (p < 0.001). In patients with severe glenoid wear, a 35° half wedge baseplate was often necessary to correct the deformity. The most common complications were stress reactions/fractures.

A metal wedged baseplate can achieve neutral inclination in all patients, minimising bone reaming and preserving lateralisation with good two-year outcomes.

IV (case series with no comparison group).

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

With the use of a 3D planning software (Blueprint) for RSA, 41 shoulders in 41 consecutive patients (17 males and 24 females; means age 73 years (SD 7)) undergoing RSA were planned. For the same anteroposterior positioning and retroversion of the glenoid implant, four different glenoid baseplate configurations were used on each shoulder to compare ROM: 1) no correction of the RSA angle and no lateralization (C-L-); 2) correction of the RSA angle with medialization by inferior reaming (C+M+); 3) correction of the RSA angle without lateralization by superior compensation (C+L-); and 4) correction of the RSA angle and additional lateralization (C+L+). The same humeral inlay implant and positioning were used on the humeral side for the four different glenoid configurations with a 3 mm symmetric 135° inclined polyethylene liner.

The configuration with lateralization and correction of the RSA angle (C+L+) led to better ROM in flexion, extension, adduction, and external rotation (p ≤ 0.001). Only internal rotation was not significantly different between groups (p = 0.388). The configuration where correction of the inclination was done by medialization (C+M+) led to the worst ROM in adduction, extension, abduction, flexion, and external rotation of the shoulder.

Our software study shows that, when using a 135° inlay reversed humeral implant, correcting glenoid inclination (RSA angle 0°) and lateralizing the glenoid component by using an angled bony or metallic augment of 8 to 10 mm provides optimal impingement-free ROM.

Scapular notching is a common complication of reverse total shoulder arthroplasty (RTSA). Although the notching rate has reduced significantly thanks to modifications to the surgical technique and humeral and glenoid components, uncontrollable polyethylene (PE)-induced osteolysis can still occur. In contrast to conventional-bearing (CB-RTSA), inverted-bearing RTSA (IB-RTSA) systems, with PE glenospheres and metal or ceramic humeral liners, avoid PE abrasion through scapulohumeral contact. If present, the resulting notch has a different size and configuration than with CB-RTSA. Thus, a modified notching classification seems reasonable. Even in CB-RTSA, the early stages of notching show a different configuration than implied by the established Nerot-Sirveaux classification; therefore, a modification of the classification system is recommended.

In a prospective multicentre study, 250 cases underwent IB-RTSA. Of these, 39 died, and 28 were lost to follow-up for other reasons, leaving 183 shoulders for the final follow-up examination at a mean of 120.7 months (range 84.1-172.4 months). In the CB-RTSA group, we retrospectively evaluated radiographs of 59 consecutive patients with a follow-up ranging from 2 to 7 years. We analysed the appearance, evolution over time, and location of bone loss on the scapular neck according to the modified Nerot-Sirveaux classification.

In IB-RTSA, notching resulted in a new morphological configuration: In contrast to the Nerot-Sirveaux classification, notching began far from the baseplate as an impression or abrasion of the humeral component in the inferior scapular rim. Due to simultaneous mechanical ablation, the defect gradually enlarged, but usually did not contact the baseplate or extend beyond the inferior peg. No signs of PE-induced osteolysis were found. The notching rate reached 19% after 2 years and approached 36% after 10 years. Most shoulders had grade 0 notching (64%), followed by grade 1 (29%); extensive erosion (grade 4) was not observed. In the CB-RTSA group, a small bony impression or erosion without signs of PE-induced osteolysis was observed medial to the scapular neck, without contact with the metaglene in the early phase, which was similar to the impression of the humeral component in IB-RTSA. The notching rate was 86% for CB-RTSA.

A new classification was developed for IB-RTSA, which corresponds to the pathophysiological processes and is compatible with the existing Nerot-Sirveaux classification. Bone erosion in CB-RTSA is not adequately represented by the established classification in the early stages. For this reason, a supplement to the existing classification is presented.

Level 4, Case Series, Treatment Study.

The implications of notching in reverse shoulder arthroplasty (RSA), and its relation with the rate of complications are still unclear. Our main aim was to retrospectively study the notching incidence in the three most used implants in our practice, considering their different neck-shaft angle (NSA) and determine its relation with implant failure, or other complications.

We retrospectively reviewed medical and imaging records of 259 patients who underwent RSA in our hospital, including surgery reports, prosthesis designs and techniques. We assessed all radiographs taken during the follow up to evaluate notching incidence, progression and signs of failure.

Notching occurred in 35% cases. The average time to notch development was 19 months. Implants with a lower NSA showed significantly lower incidence of notching when compared to other implants (P < 0.001). In a multivariate analysis, the NSA proved to be an independent predictor for the occurrence of notching in this series.

According to our results, higher NSA is an independent predictor of the occurrence of notching. There was significant increase in the notching rate with follow up. In the future, larger case series with longer follow-up are necessary to evaluate the relation between notching and radiological and clinical complications.

Reverse shoulder arthroplasty (RSA) is a frequently used therapy for complex proximal humeral fractures and posttraumatic disorders. The present study's purpose was to assess the clinical and radiological outcome of primary and secondary RSA, and to analyze the impact of refixation of the greater tuberosity (GT).

28 patients with primary fracture RSA and 18 patients with RSA due to posttraumatic disorders were examined with a mean clinical follow-up of 2.5 ± 1.73 years. Operative details and radiographs were retrospectively reviewed. Additional analyses were performed for healed and non-healed GT in primary RSA.

Patients with fracture RSA had higher Constant-Murley score (CMS) than secondary RSA without reaching significance (p = 0.104). No significant difference was present for the quality of life measured by the Short Form 36 (SF 36) and the range of motion. In primary RSA, 78.6% GT healed anatomically. Compared to non-healed GT, patients with healed GT had a significantly higher CMS (p = 0.011), external rotation (p = 0.026) and forward flexion (p = 0.083), whereas DASH score was lower without a significant difference (p = 0.268). SF 36 showed no significant difference. Patients with healed GT had a more neutral glenoid version (p = 0.009).

Superior range of motion and clinical outcome scores were present for anatomically healed GT. Therefore, refixation of the tuberosities is recommended. Secondary RSA can result in inferior results compared to primary RSA, so patients need to be adequately informed.

» Reverse total shoulder arthroplasty was designed to function in the rotator cuff deficient shoulder by adjusting the glenohumeral center of rotation (COR) to maximize deltoid function.» Adjustments in the COR ultimately lead to changes in resting tension of the deltoid and remaining rotator cuff, which can affect implant stability and risk of stress fracture.» Soft-tissue balance and complication profiles can be affected by humeral component (version, neck shaft angle, and inlay vs. onlay) and glenoid component (sagittal placement, version, inclination, and lateralization) design and application.» A good understanding of the effects on soft-tissue balance and complication profile is critical for surgeons to best provide optimal patient outcomes.

The aim of this systematic review was to collect evidence on the following 10 technical aspects of glenoid baseplate fixation in reverse total shoulder arthroplasty (rTSA): screw insertion angles; screw orientation; screw quantity; screw length; screw type; baseplate tilt; baseplate position; baseplate version and rotation; baseplate design; and anatomical safe zones. Five literature libraries were searched for eligible clinical, cadaver, biomechanical, virtual planning, and finite element analysis studies. Studies including patients >16 years old in which at least one of the ten abovementioned technical aspects was assessed were suitable for analysis. We excluded studies of patients with: glenoid bone loss; bony increased offset-reversed shoulder arthroplasty; rTSA with bone grafts; and augmented baseplates. Quality assessment was performed for each included study. Sixty-two studies were included, of which 41 were experimental studies (13 cadaver, 10 virtual planning, 11 biomechanical, and 7 finite element studies) and 21 were clinical studies (12 retrospective cohorts and 9 case-control studies). Overall, the quality of included studies was moderate or high. The majority of studies agreed upon the use of a divergent screw fixation pattern, fixation with four screws (to reduce micromotions), and inferior positioning in neutral or anteversion. A general consensus was not reached on the other technical aspects. Most surgical aspects of baseplate fixation can be decided without affecting fixation strength. There is not a single strategy that provides the best outcome. Therefore, guidelines should cover multiple surgical options that can achieve adequate baseplate fixation.

With advancements in the technology, techniques, and biomechanical understanding of shoulder arthroplasty, higher rates of postoperative return to various sports have been seen in the past decade.

To observe the return-to-golf rate after various types of shoulder arthroplasty (anatomic total shoulder arthroplasty [TSA], hemiarthroplasty [HA], and reverse total shoulder arthroplasty [RSA]) and also to review the protocols for return to golf.

Scoping review; Level of evidence, 4.

The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed in a search of PubMed, JSTOR, Google Scholar, ScienceDirect, and CORE using the keywords "return to sport,""shoulder arthroplasty,""golf,""TSA,""shoulder arthroplasty,""hemiarthroplasty,""reverse shoulder arthroplasty,""RSA,""sports," and "athlete." Of 145 preliminary results, 10 retrospective studies (n = 178 patients) published between 1998 and 2021 were included in the final analysis.

The mean patient age was 65 years. Of the 172 patients with reported return-to-sport rates, the mean return-to-golf rate was 75.8% for all types of shoulder arthroplasty. Of these 172 patients, 107 patients were categorized by type of procedure: Anatomic TSA had the highest return-to-golf rate at 77.6% (49/107), followed by HA at 64.3% (14/107) and RSA at 59.1% (44/107). Four studies commented on return to the full 18 holes of golf, with a return-to-sport timeline ranging from 5 to 6 months postoperatively. One study specified the return-to-golf timeline based on the type of shot and reported the mean number of weeks before putting, chipping, and returning to the course as 20, 22, and 27 weeks, respectively. Two studies that reported on golf playing frequency noted an increase from before to 1 year after TSA, from a mean of 1.6 and 0.7 times per week to 2.0 and 1.7 times per week, respectively. Only 1 study, published in 1998, provided a comprehensive return-to-golf protocol.

The return-to-golf rate after shoulder arthroplasty was highest after anatomic TSA (78%) compared with HA (64%) and RSA (59%). The most commonly reported duration before returning to a full 18 holes was 5 to 6 months, but patients returned to putting and chipping earlier.

We reviewed the shoulder arthroplasty (SA) literature to correlate citations, methodological characteristics and quality of most-cited articles in this field. We hypothesized that a greater number of citations would be found for high-quality clinical studies.

We searched the Web of Knowledge database for the 50 most-cited articles about SA and collected author name, publication year, country of origin, journal, article type, level of evidence (LoE), subject of paper, type of arthroplasty and metrics (number of citations and citation rate). Coleman Methodology Score (CMS) was computed for clinical articles. Statistical analysis of variance and correlation coefficients were used to investigate the relationship between different variables.

Out of the selected 50 studies on SA, 26% were nonclinical. There were 15,393 citations overall (mean 307.8), with a mean 19.5 citations per year (range 48.3-6.7). Thirty or 60% of all articles were LoE IV. All studies were published between 1984 and 2011 in 8 journals. Reverse SA (RSA) was the most common subject (36% of studies). The United States was the country responsible for most contributions (50% of studies). CMS ranged from 81 to 38 (mean 59.6). RSA received the highest number of citations (P < .001), independently from country of origin (P = .137) and LoE (P = .723). CMS correlated with citation rate (r = 0.397; P = .013) and publication year (tau = 0.397; P = .013), but not with LoE (P = .204).

In SA literature, citation rate positively correlates with methodological quality of a study, independently from publication country and LoE. Among most-cited papers, RSA is the most common standalone subject.

Impingement is a common complication of reverse shoulder arthroplasty. Placement of the baseplate with a wide impingement-free angle is ideal; however, there are few studies on Asian populations, which have smaller height and physique, and there is a lack of guidance on achieving optimal outcomes. The purpose of the present study was to explore the impingement-free range of motion reverse shoulder arthroplasty and analyze the suitable baseplate position or tilt for the Asian population using simulation software.

We uploaded computed tomography scan data from 20 Asian patients to three-dimensional (3D) simulation software. The implantation of the reverse shoulder arthroplasty component was performed on the 3D humerus and scapula using software, and range of motion was assessed until impingement occurred.

The range of motion in flexion significantly improved when the baseplate was lowered up to 3 mm inferiorly. Range of motion in abduction and internal and external rotation significantly improved as the baseplate was lowered up to 4 mm. There was no significant difference in range of motion in any motion after changing the inferior tilt, except in internal and external rotation.

The range of motion in abduction, flexion, and internal and external rotations significantly improved with increased inferior offset. These results may prove valuable in determining the optimal baseplate position for RSA, particularly in Asian populations.

Reverse total shoulder replacement (rTSR) improves pain and function in patients with a wide range of shoulder pathology. Anterosuperior (AS) and deltopectoral (DP) approaches are widely used to gain access to the glenohumeral joint in arthroplasty. Our aim was to systematically review the literature comparing outcomes of these two approaches when performing rTSR for degenerative glenohumeral arthritis.

Systematic review was performed with an electronic multi-database search (Pubmed, Medline & Embase) according to PRISMA guidelines on 18th September 2022. Data from published studies of any study design that met the inclusion criteria were extracted, reviewed and synthesized.

A total of 38 studies were identified for full text review, of which four were included. No significant difference in pain and range of motion were observed between approaches. Scapular notching was more common in the anterosuperior approach. Low rates of instability and intra-operative fracture were observed in both.

Both approaches demonstrate similar clinical outcomes with reference to pain, range of motion and complications when performing rTSR indicated for degenerative joint disease. However, further well-designed studies are required.

Glenohumeral osteophytes (OPs) can adversely influence postoperative range of motion (ROM) following shoulder arthroplasty due to mechanical impingement. Though commercial three-dimensional preoperative planning software (3D PPS) is available to simulate ROM before and after OP resection, little is known about the magnitude of effect OPs and their subsequent removal have on simulated glenohumeral ROM.

Included patients were 1) indicated for reverse total shoulder arthroplasty (rTSA) using 3D PPS and 2) presented with glenoid and/or humeral head OPs on preoperative two-dimensional computed tomography (2D-CT) imaging. Thirty patients met the inclusion criteria (9 females, 21 males; mean age 70.45 ± 4.99 years, range 63-80 years). All subjects (n = 30) presented with humeral OPs (mean volume: 2905.16 mm3, range 109.1-11,246 mm3), while 11 subjects also presented with glenoid OPs (mean volume 108.06 mm3, range 37.59-791.4 mm3). Preoperative CTs were used to calculate OP volume (mm3) and OP circumferential extent (clockface). Mean clockface position for circumferential humeral OPs originated at 6:09 (range 4:30-7:15) and extended to 8:51 (range 8:15-10:15). Mean clockface position for glenoid OPs originated at 3:00 (range 2:00-5:00) and extended to 6:16 (range 3:00-7:30). 3D implants on PPS were standardized to achieve 0° of version, 0° of inclination and 4 mm of net lateralization. Thirty-nine and thirty-six mm glenospheres were used for males and females, respectively. 3D PPS was used to evaluate simulated ROM differences before and after OP removal in the planes of adduction (ADD), abduction, internal rotation (IR), external rotation (ER), extension, and flexion. Impact of OP volume and circumferential extent on pre and postop removal ROM were also analyzed.

Humeral OP removal significantly increased impingement-free ADD, IR, ER, extension, and flexion. Removal of larger (mm3) humeral OPs positively correlated with improvement in IR (R = 0.452, P = .011), ER (R = 0.394, P = .033), and flexion (R = 0.500, P < .01). Greater circumferential extent of humeral OPs correlated with worse preremoval ROM in the planes of ADD (R = 0.364, P = .02) and extension (R = 0.403, P = .04), and improvements in ER postop removal (R = 0.431, P = .03).

Humeral OP removal significantly increases impingement-free ADD, IR, ER, extension, and flexion in simulated 3D PPS models following rTSA. Magnitude of simulated ROM improvement is influenced by initial humeral OP volume and circumferential clockface extent. Surgeons should consider these effects when using 3D PPS for rTSA planning to optimize postoperative ROM prognostics.

The role of the subscapularis (Ssc) tendon does not yet have a well-defined role in RSA. The purpose of the present study was to evaluate if the repair of the Ssc in RSA improves overall clinical and radiographic results and if it has the same results using a medialized design humeral stem compared to a lateralized design.

Eighty-four consecutive patients undergoing RSA were retrospectively analyzed. Nine patients were lost at FU. Two implants with similar glenosphere design and different stem design (medialized and lateralized) were used. The Ssc was repaired in case of good quality of the fibers and reducibility without tension intraoperatively. Patients were divided into four groups for data analysis depending on whether they had received a medialized or lateralized design and Ssc repair or not. Patients were reviewed at an average follow-up of 40.8 ± 13.1 months. Clinical outcome measures included Active range of motion (ROM), strength, visual analog scale (VAS), Constant-Murley score (CMS), and the American Shoulder and Elbow Surgeons score (ASES). Radiographic evaluation at final follow-up was performed to assess scapular notching, stress shielding, and radiolucent lines.

No statistically significant clinical differences (p > 0.05) emerged between Lat/Ssc+ and Lat/Ssc-. Conversely, the patients belonging to the Med/Ssc- group reported statistically worse (p < 0.05) results than the Med/Ssc + group in terms of VAS, ASES and CMS. Statistically worse (p < .05) results in the Med/Ssc- group than in the Med/Ssc + were found also in active ROM achieved in FE, ABD, ER1 and ER2, and in the strength obtained in FE, ABD and ER2. Scapular notching was reported in 3 shoulders (15.7%) in Lat/Ssc+ group and in 7 shoulders (50%) in Lat/Ssc- group, while it was reported in 4 shoulders (14.2%) in Med/Ssc + group and in 6 shoulders (42.8%) in Med/Ssc- group. Stress shielding was observed in 6 cases in Lat/Ssc+ group (31.6%), in 8 cases in Lat/Ssc- group (57.1%), in 3 cases (10.7%) in Med/Ssc + group and 4 cases in Med/Ssc- group (28.6%).

Patients undergoing RSA show clinical improvements at mid-term follow-up with a low rate of complications, regardless of the use of a medialized or a lateralized humeral stem design. Ssc repair is associated with better functional outcomes in the cohort of medialized stem, while it did not yield significant differences in the cohort of lateralized stem.

Level III; Retrospective Cohort Comparison; Treatment Study.

Two surgical techniques were compared : Standard BIO-RSA, performed with a glenoid eccentric reaming along with a cylindric bone graft augmentation vs. the Angled BIO-RSA, performed with a glenoid concentric reaming and a defect correction with an angled bone graft.

Patients undergoing RSA from January 2016 to April 2019, with one of the two techniques being performed, were retrospectively reviewed. Glenoids were classified according to Favard. Clinical (Constant-Murley, VAS and ROM) and radiographic (superior tilt correction) data were collected pre-operatively and at 12 months post-operatively.

141 shoulders were included. Angled BIO-RSA group showed statistically significant better outcomes in terms of forward flexion (149.9° Vs 139.3°) and abduction (136.4° Vs 126.7°). The use of an Angled BIO-RSA showed a statistically significant better superior tilt correction (1.252° Vs 4.09°). Angled BIO-RSA, leads to a better inclination correction and a mean postoperative tilt value inferior to 5° in E1 and E3 differently from standard BIO-RSA.

Both techniques were able to correct glenoid superior inclination with excellent postoperative short-term results. However, angled BIO-RSA technique appears to be more effective in ensuring a correct inclination of the prosthetic glenoid component with better clinical outcomes.

Reverse total shoulder arthroplasty (RSA) is an effective treatment option for rotator cuff arthropathy. Scapular notching following RSA remains a major complication and has a high incidence. This finite element analysis (FEA) study provides a future reference for the optimal design of the insert component of RSA. This study aims to clarify the effect of a new design RSA with a notched insert on the range of adduction, scapular notching, and stress variation of its insert component using three-dimensional (3D) FEA.

3D nominal Grammont-type monobloc RSA implant components are modeled on the sawbones glenohumeral joint. The polyethylene insert is redesigned with notching of the inferior part. The comparison of standard and notched designs was performed by FEA for stress pressure of scapular notching and the degree of adduction. 3D mesh models are created for stress analysis to compare the results between standard and notched inserts for the adduction.

The redesigned notched inserts had an additional ~ 11.2° on adduction and prevented scapular notching. The stress analysis results for the notched insert design were lower than the standard ones (4.7 vs 22.4 Kpa).

Notched insert design of Grammont-type RSA could provide additional adduction with lower stress on the glenoid, leading to less scapular notching. Further experimental and clinical studies on different RSA types are needed to verify this effect.

Basic Science Study; Biomechanics and Computer Modeling.

Citation analyses have been used to understand the impact that a group of publications has on its field. As the techniques and indications of reverse total shoulder arthroplasty (RTSA) continue to expand, it is important to identify articles that can orient readers to the history, evolution, and current status of the body of RTSA literature. The purpose of this study was to identify and analyze the 50 most-cited articles related to RTSA.

Various Boolean queries were searched on the Clarivate Analytics Web of Science. Information collected included author name, publication year, country of origin, journal name, article type, total number of citations, and level of evidence.

Top 50 most-cited articles amassed a total of 10,521 citations. The most-cited article was cited a total of 766 times. The most common study designs were case series (28) and cohort studies (9). Authors from the United States (24) contributed the most to included papers, followed by France (19) and Switzerland (8).

The most-cited articles on RTSA are expert opinions, case studies, and cohort studies published by American authors. As RTSA continues to grow over the next decade, studies with higher levels-of-evidence may overtake articles included in this analysis.

Optimal glenosphere positioning in reverse shoulder arthroplasty (RSA) remains highly debated. We aimed to characterize the association between the prosthesis scapular neck angle (PSNA) and postoperative range of motion (ROM) and clinical outcome scores.

A retrospective review of 284 RSAs using a single design with minimum 2-year follow-up was performed. Glenosphere tilt was measured postoperatively using PSNA. ROM and functional outcome scores were assessed preoperatively and at latest follow-up. The PSNA was dichotomized to inferior or superior groups (>90° vs ≤ 90°, respectively) and stratified into quartiles; ROM and outcome score measures were compared between groups controlling for inferior glenosphere overhang.

No range of PSNA was consistently associated with superior ROM, clinical outcome scores, or rates of complications including scapular notching. However, greater preoperative to postoperative improvement in active FE was found for superiorly (PSNA ≤ 90°) versus inferiorly tilted glenospheres (37° ± 33° vs 53° ± 35°, P  =  0.005) and the greater improvement in active FE (57° ± 35°, P  =  0.004) was further isolated to the first quartile (mean 85.1° ± 3.5°).

A lack of variation in clinical outcomes based on PSNA suggests negligible short-term (median follow-up 3.1 years) clinical significance when glenosphere tilt falls within the distribution of this cohort (mean 92.6° ± 6.2°).

The aim of this study was to compare the clinical and radiological outcomes of reverse shoulder arthroplasty (RSA) using small and standard baseplates in Asian patients, and to investigate the impact of a mismatch in the sizes of the glenoid and the baseplate on the outcomes.

This was retrospective analysis of 50 and 33 RSAs using a standard (33.8 mm, ST group) and a small (29.5 mm, SM group) baseplate of the Equinoxe reverse shoulder system, which were undertaken between January 2017 and March 2021. Radiological evaluations included the size of the glenoid, the β-angle, the inclination of the glenoid component, inferior overhang, scapular notching, the location of the central cage in the baseplate within the vault and the mismatch in size between the glenoid and baseplate. Clinical evaluations included the range of motion (ROM) and functional scores. In subgroup analysis, comparisons were performed between those in whom the vault of the glenoid was perforated (VP group) and those in whom it was not perforated (VNP group).

Perforation of the vault of the glenoid (p = 0.018) and size mismatch in height (p < 0.001) and width (p = 0.013) were significantly more frequent in the ST group than in the SM group. There was no significant difference in the clinical scores and ROM in the two groups, two years postoperatively (all p > 0.05). In subgroup analysis, the VP group had significantly less inferior overhang (p = 0.009), more scapular notching (p = 0.018), and more size mismatch in height (p < 0.001) and width (p = 0.025) than the VNP group.

In Asian patients with a small glenoid, using a 29.5 mm small baseplate at the time of RSA was more effective in reducing size mismatch between the glenoid and the baseplate, decreasing the incidence of perforation of the glenoid vault, and achieving optimal positioning of the baseplate compared with the use of a 33.8 mm standard baseplate. However, longer follow-up is required to assess the impact of these findings on the clinical outcomes.

Various radiological parameters have been measured in the Reverse Shoulder Arthroplasty (RSA) and correlated to patient outcomes, to determine best baseplate position. Results remain unclear with respect to certain parameters such as inferior baseplate tilt. We have investigated our series of patients to clarify the relationship between radiological parameters and patient outcomes.

We conducted a UK based bi-centre retrospective review of 156 prostheses. Critical shoulder angle (CSA), RSA angle (RSAA), Overhang and Deltoid Lever Arm (DLA) were measured on preoperative and postoperative radiographs. Range of motion and Oxford Shoulder Score (OSS) (range 1-8 years) were obtained. We assessed for scapular notching at minimum 1 year follow up (n = 138).

Decreased postoperative CSA and increased DLA were associated with higher OSSs (P = 0.001 and 0.019). Increased overhang and DLA were associated with increased flexion (P = 0.033 and 0.024 respectively). Multivariate analysis showed that CSA and DLA affected notching rate (P = 0.002 and 0.007).

Baseplate tilt in relation to the acromion (CSA) and DLA are the most predictive parameters for notching and OSS. We recommend considering a maximum CSA of 26 degrees to decrease notching rate and improve OSS. We recommend considering an Overhang of at least 6 mm to improve FF.

To avoid dislocation of the shoulder joint after reverse total shoulder arthroplasty, it is important to achieve sufficient shoulder stability when placing the implant components during surgery. One parameter for assessing shoulder stability can be shoulder stiffness. The aim of this research was to develop a temporary reverse shoulder implant prototype that would allow intraoperative measurement of shoulder stiffness while varying the position of the implant components. Joint angle and torque measurement techniques were developed to determine shoulder stiffness. Hall sensors were used to measure the joint angles by converting the magnetic flux densities into angles. The accuracy of the joint angle measurements was tested using a test bench. Torques were determined by using thin-film pressure sensors. Various mechanical mechanisms for variable positioning of the implant components were integrated into the prototype. The results of the joint angle measurements showed measurement errors of less than 5° in a deflection range of ±15° adduction/abduction combined with ±45° flexion/extension. The proposed design provides a first approach for intra-operative assessment of shoulder stiffness. The findings can be used as a technological basis for further developments.

Superior inclination of the base plate in reverse shoulder arthroplasty (RSA) is underestimated and may lead to major setbacks in terms of functional outcomes due to the altered biomechanics. Joint instability, scapular notching, and loosening of the glenoid component are considered the most serious sequelae. Therefore, a thorough preoperative radiological assessment of the affected shoulder joint and customized design of the prosthesis according to the glenoid morphology are decisive and directly correlated to the outcome. In this article, we propose a simple radiographic technique to assess the inclination of the glenoid preoperatively, which identifies the need for intraoperative correction.

One hundred inconspicuous shoulder radiographs were included in the control group (CG) to define the normal ranges of the base plate orientation angle (BOA) and the base plate correction angle (BCA). Further, both angles were measured on 2-dimensional (2D) computed tomography scans of patients with proximal humerus fractures as well as radiographs, 2D and 3-dimensional (3D) computed tomography scans of patients with cuff tear arthropathy who underwent RSA between 2018 and 2021. The interobserver reliability among three independent testers was evaluated by calculating the intraclass correlation coefficient. In cuff tear arthropathy cases, the BOA and BCA measurements on different imaging modalities were compared using the Wilcoxon test. Possible variations of both angles' values based on glenoid erosion types, according to the Favard classification, were also investigated.

Regardless of the imaging modality used, the interobserver reliability was excellent among three independent observers. In the CG, the mean BOA and BCA values were 118° ± 6° and 17° ± 5°, respectively. The mean corrected BOA values of the CG and fracture group were 136° ± 5° and 140° ± 5°, respectively. In contrast to the BCA values, the BOA measurements on radiographs showed a statistically significant difference compared to those obtained on 2D- and 3D scans in the cuff arthropathy group. Further, both angles' values varied according to the extent and location of the glenoid erosion. The lowest mean BOA and highest mean BCA values were observed in cases with Favard glenoid type E3.

The BOA and the BCA are reliable tools proposed to aid in precisely positioning the glenoid component in RSA in the preoperative setting. Whereas, the BOA determines the inclination of the inferior glenoid segment, the BCA represents the extent of correction required to obtain a neutral inclination of the base plate. Glenoid type E3 of the Favard classification with superior wear is particularly susceptible to base plate superior tilt.

Scapular notching is a well-known postoperative complication of reverse total shoulder arthroplasty (RTSA). However, subacromial notching (SaN), a subacromial erosion caused by repeated abduction impingement after RTSA, has not been previously reported in a clinical setting. Therefore, this study aimed to assess the risk factors and functional outcomes of SaN after RTSA.

We retrospectively reviewed the medical records of 125 patients who underwent RTSA with the same design between March 2014 and May 2017 and had at least 2 years of follow-up. SaN was defined as subacromial erosion observed at the final follow-up but not on the X-ray 3 months after surgery. Radiologic parameters representing the patient's native anatomy and degrees of lateralization and/or distalization during surgery were evaluated using preoperative and 3 months postoperative X-rays. The visual analogue scale of pain, active range of motion, and American Shoulder and Elbow Surgeons score were assessed preoperatively and at the final follow-up to evaluate the functional outcomes of SaN.

SaN occurred in 12.8% (16/125) of enrolled patients during the study period. Preoperative center of rotation-acromion distance (P = .009) and postoperative humerus lateralization offset, which evaluated the degree of lateralization after RTSA (P = .003), were risk factors for SaN. The preoperative center of rotation-acromion distance and postoperative humerus lateralization cutoff values were 14.0 mm and 19.0 mm, respectively. The visual analogue scale of pain (P = .01) and American Shoulder and Elbow Surgeons score (P = .04) at the final follow-up were significantly worse in patients with SaN.

SaN might adversely affect postoperative clinical outcomes. As SaN correlated with patients' anatomical characteristics and degree of lateralization during RTSA, the implant's degree of lateralization should be adjusted according to the patient's own anatomical characteristics.

Determine incidence of shoulder arthroplasty complications identified on computed tomography (CT).

Retrospective institutional database review of patients with shoulder arthroplasties who underwent CT between 01/2006-11/2021 at a tertiary academic referral center with subspecialized orthopedic shoulder surgeons. CT reports were reviewed for arthroplasty type and complication. Data were stratified and summarized. Associations between complications and arthroplasty types were determined with Chi-squared goodness of fit test.

Eight hundred twelve CTs in 797 unique patients were included (438 (53.9%) females and 374 (46.1%) males; mean age 67 ± 11 years). There were 403 total shoulder arthroplasties (TSA), 317 reverse total shoulder arthroplasties (rTSA), and 92 hemiarthroplasties (HA). Complications were present in 527/812 (64.9%) and incidences were: loosening/aseptic osteolysis 36.9%, periprosthetic failure 21.6%, periprosthetic fracture 12.3%, periprosthetic dislocation 6.8%, joint/pseudocapsule effusion 5.9%, prosthetic failure 4.8%, infection 3.8%, and periprosthetic collection 2.1%. Complications per arthroplasty were: 305/403 (75.7%) TSAs, 176/317 (55.5%) rTSAs, and 46/92 (50%) HAs (p < 0.001). Periprosthetic fracture (20.8%), prosthetic dislocation (9.8%), and prosthetic failure (7.9%) were highest in rTSAs (p < 0.001, p < 0.013, p < 0.001, respectively). Loosening/aseptic osteolysis most frequent in TSAs (54.1%) (p < 0.001). Periprosthetic failure most frequent in HA (32.6%) (p < 0.001). Significant associations were identified with joint/pseudocapsule effusion and loosening/aseptic osteolysis (p = 0.04) and prosthetic dislocation (p < .001).

In this single tertiary academic referral center cohort, the incidence of shoulder arthroplasty complication identified on CT was 64.9% and the most commonly occurring complication was loosening/aseptic osteolysis (36.9%). TSA had the highest incidence of complication (75.7%).

Compromised abduction ability after reverse shoulder arthroplasty is primarily linked to limited glenohumeral range of motion while scapulothoracic mobility can typically be maintained. Glenohumeral joint forces strongly depend on the resulting scapulohumeral rhythm, however, an association between the acting muscle and joint forces and the subject-specific scapulohumeral rhythm after reverse shoulder arthroplasty has not been established.

Eleven reverse shoulder arthroplasty patients were divided into groups of poor and excellent abduction ability. Subject-specific models were developed and scaled for each patient using existing motion capture data in AnyBody™. Shoulder muscle and joint forces were obtained using inverse dynamics calculations during shoulder abduction to 100° in the scapula plane. The scapulohumeral rhythm, the resting abduction angle and internal body forces between the outcome groups were compared using a Mann Whitney U test.

The mean glenohumeral and scapulothoracic contribution to overall shoulder abduction for the excellent group was on average 9.7% higher and 21.4% lower, respectively, compared to the mean of the poor group. For shoulder abduction angles between 30° and 60°, the excellent group demonstrated on average 25% higher muscle forces in the anterior deltoid which was significantly higher compared to the poor outcome patients. Scapulothoracic muscle activity did not differ significantly between the two functional groups.

Accordingly, rehabilitation strategies focusing on strengthening the anterior part of the deltoid in particular may improve clinical outcomes.

The complications of the conventional medialized design for reverse total shoulder arthroplasty (RSA) are increased scapular notching, and decreased external rotation and deltoid wrapping. Currently, lateralization design RSA, which avoid scapular notching and improve impingement-free range of motion, is commonly used. Especially, humeral lateralization design was most commonly used and glenoid lateralization design was preferred for glenoid abnormities. We compared mid-term clinical and radiologic outcomes of glenoid and humeral lateralization RSA in an Asian population in this study.

We enrolled 124 shoulders of 122 consecutive patients (mean age 73.8 ± 6.8 years) who received glenoid or humeral lateralization RSA from May, 2012 to March, 2019. We divided these patients into two groups according to RSA using either glenoid or humeral lateralization design. These different designs were introduced consecutively in Korea. The clinical and radiological results of 60 glenoid lateralization RSA (Group I, 60 patients) and 64 humeral lateralization RSA (Group II, 62 patients) were retrospectively evaluated and also were compared between the two groups. All patients were followed for mean 3 years.

The clinical and radiologic outcomes of the two groups did not differ significantly, including scapular notching (p = 0.134). However, humeral lateralization RSA showed a larger glenoid-tuberosity (GT) distance (p = 0.000) and less distalization shoulder angle (DSA) (p = 0.035). The complication rate did not differ significantly either. But, revision surgery was performed for 2 humeral loosening in the Group II.

The clinical and radiologic outcomes of the two groups did not differ significantly, including scapular notching at mid-term follow-up. However, humeral lateralization design showed larger GT distance and less DSA. Humeral lateralization design RSA could preserve the normal shoulder contour due to a larger GT distance (more lateralization) and provide less deltoid tension due to less DSA (less distalization of COR).

Functional internal rotation (IR) is a combination of extension and IR. It is clinically often limited after reverse total shoulder arthroplasty (RTSA) either due to loss of extension or IR in extension. It was the purpose of this study to determine the ideal in-vitro combination of glenoid and humeral components to achieve impingement-free functional IR.

RTSA components were virtually implanted into a normal scapula (previously established with a statistical shape model) and into a corresponding humerus using a computer planning program (CASPA). Baseline glenoid configuration consisted of a 28 mm baseplate placed flush with the posteroinferior glenoid rim, a baseplate inclination angle of 96° (relative to the supraspinatus fossa) and a 36 mm standard glenosphere. Baseline humeral configuration consisted of a 12 mm humeral stem, a metaphysis with a neck shaft angle (NSA) of 155° (+ 6 mm medial offset), anatomic torsion of -20° and a symmetric PE inlay (36mmx0mm). Additional configurations with different humeral torsion (-20°, + 10°), NSA (135°, 145°, 155°), baseplate position, diameter, lateralization and inclination were tested. Glenohumeral extension of 5, 10, 20, and 40° was performed first, followed by IR of 20, 40, and 60° with the arm in extension of 40°-the value previously identified as necessary for satisfactory clinical functional IR. The different component combinations were taken through simulated ROM and the impingement volume (mm³) was recorded. Furthermore, the occurrence of impingement was read out in 5° motion increments.

In all cases where impingement occurred, it occurred between the PE inlay and the posterior glenoid rim. Only in 11 of 36 combinations full functional IR was possible without impingement. Anterosuperior baseplate positioning showed the highest impingement volume with every combination of NSA and torsion. A posteroinferiorly positioned 26 mm baseplate resulting in an additional 2 mm of inferior overhang as well as 6 mm baseplate lateralization offered the best impingement-free functional IR (5/6 combinations without impingement). Low impingement potential resulted from a combination of NSA 135° and + 10° torsion (4/6 combinations without impingement), followed by NSA 135° and -20° torsion (3/6 combinations without impingement) regardless of glenoid setup.

The largest impingement-free functional IRs resulted from combining a posteroinferior baseplate position, a greater inferior glenosphere overhang, 90° of baseplate inclination angle, 6 mm glenosphere lateralization with respect to baseline setup, a lower NSA and antetorsion of the humeral component. Surgeons can employ and combine these implant configurations to achieve and improve functional IR when planning and performing RTSA.

Basic Science Study, Biomechanics.

Over 35 years ago, the pioneer Paul Grammont from Lyon published his ideas of a reversed semi-constraint prosthesis improving the moment arm of the deltoid by medializing the center of rotation and lengthening of the arm and thus increasing deltoid muscle tension [...].

A detailed overview of the basic science and clinical literature reporting on the challenges for the optimization of reverse shoulder arthroplasty (RSA) is presented in two review articles. Part I looks at (I) external rotation and extension, (II) internal rotation and the analysis and discussion of the interplay of different factors influencing these challenges. In part II, we focus on (III) the conservation of sufficient subacromial and coracohumeral space, (IV) scapular posture and (V) moment arms and muscle tensioning. There is a need to define the criteria and algorithms for planning and execution of optimized, balanced RSA to improve the range of motion, function and longevity whilst minimizing complications. For an optimized RSA with the highest function, it is important not to overlook any of these challenges. This summary may be used as an aide memoire for RSA planning.

There is increasing interest in reverse total shoulder arthroplasty (RTSA) as a reliable treatment for arthritic, rotator cuff deficient shoulders. Humeral and glenoid version are controversial parameters that can influence internal and external rotation, muscular forces, and implant stability as outcomes of RTSA. The aim of this study was to obtain an overview of the current knowledge on the effect of both humeral component version and glenoid component version and give recommendations on their most optimal degree for RTSA. A comprehensive quantitative review of the published literature on the effect of humeral version and glenoid version in RTSA was performed, to identify its influence on the range of movement, muscle forces, and intrinsic stability of the reverse prosthesis. Eleven studies were included: nine were biomechanical studies, one was a clinical-radiographic study, and one was an implant design consideration. Anterior stability can be improved by implanting the humeral component in neutral or with some anteversion. Glenoid component retroversion has been proven to reduce the likelihood of subluxation, while increasing ER and ROM at the same time. The study was conducted considering 5° anteversion; neutral; and 5°, 10°, and 20° retroversion of the glenoid component. Although a final opinion has not been yet expressed on the matter, the general consensus tends to agree on restoring 0° to 20° of retroversion of the humeral and glenoid component to yield the best outcomes.

Surgical approach is an important factor that may affect the outcomes of reverse total shoulder arthroplasty (RTSA). The most common approaches for RTSA are anterosuperior (AS) and deltopectoral (DP). However, controversy exists on which surgical approach is better. This meta-analysis aimed to compare both approaches in terms of radiological and clinical outcomes and complications.

We searched PubMed, Embase, and Cochrane Library databases for studies that compared the postoperative outcomes of the AS and DP approaches for RTSA. After screening and quality assessment of the articles, we obtained two randomized controlled trials and four retrospective comparative studies. We analyzed the radiologic outcomes, functional outcomes, and complications between the two approaches. The standardized mean difference and odds ratio were used to analyze the differences in outcomes between the two surgical approaches. Statistical significance was set at P < 0.05.

The incidence rate of glenoid implant loosening was significantly (P = 0.04) lower in the AS group than that in the DP group. In terms of forward flexion after surgery, the DP approach produced significantly (P = 0.03) better outcomes compared with the AS approach. There were no significant differences in radiological outcomes or other complication rates between the two approaches.

As a result of this meta-analysis, one of the two approaches did not bring a better result than the other. One has strength for better forward flexion and the other for a lower glenoid loosening rate. With this in mind, it is recommended to use the approach that the surgeon is most familiar with.

Range of motion (ROM) and prevention of notching remain a challenge for reverse shoulder arthroplasty (RSA). Both may be affected by the morphology of the scapula. The purpose of this study was to define anteroinferior (a) and posteroinferior (p) relevant scapular neck offset (RSNO) and to examine the hypothesis that pRSNO is significantly smaller than aRSNO, and influences rigid body motion (RBM). Adapting glenosphere implantation strategies may therefore be of value.

In this computer model study, we used deidentified computed tomographic scans of 22 patients (11 male and 11 female; mean age: 72.9 years) with massive cuff tears without joint space narrowing. Eight RSA glenoid configurations were tested with a constant neck-shaft angle (145°). Two baseplate types (25 mm; 25 + 3 mm lateralized) and 4 glenospheres (GS) (36 mm; 36 +2 mm of eccentricity; 39 mm; 39 + 3 mm) were used. RSNO was defined as the standardized measurement of the horizontal distance from the inferior extent of the GS to the bony margin of the scapula after baseplate positioning (flush to inferior glenoid extent; neutral position: 0° inclination and 0° version-both software computed).

There was a highly significant difference between pRSNO and aRSNO for both genders (P < .001). pRSNO was always smaller than aRSNO. pRSNO was strongly correlated with external rotation (ERO: 0.84) and extension (EXT: 0.74) and moderately correlated with global ROM (GROM: 0.68). There was a moderately strong correlation between aRSNO and internal rotation (IRO: 0.69). pRSNO was strongly correlated with aRSNO, EXT, ERO, IRO, adduction (ADD) and GROM (0.82, 0.72, 0,8, 0.71, 0.82, 0.76) in female patients and with EXT and ERO (0.82, 0.89) in male patients. The median pRSNO allowing for at least 45° ERO and 40° EXT was 14.2 mm for men and 13.8 mm for women. For all patients and models, pRSNO ≥14 mm increased EXT, ERO, and GROM significantly compared with pRSNO <14 mm (P < .001). The combination of lateralization and inferior overhang (eccentricity) led to the most significant increase of pRSNO for each GS size (P < .001).

This is one of the first RSA modeling studies evaluating nonarthritic glenoids of both genders. The lateral scapular extent to glenoid relationship is asymmetric. pRSNO is always smaller than aRSNO for both genders and was a critical variable for EXT and ERO, demonstrating additional strong correlation with aRSNO, IRO, ADD, and GROM in female patients. pRSNO ≥14 mm was a safe value to prevent friction-type impingement. Combining increased glenosphere size, lateralization, and inferior overhang gives the best results in this computer-simulated setting.

This study compared the clinical and radiologic results of reverse shoulder arthroplasty (RSA) using either the subscapularis-sparing deltopectoral approach (SSDA) or traditional deltopectoral approach (TDA) in cuff tear arthropathy patients.

We retrospectively evaluated 71 patients who underwent RSA for cuff tear arthropathy between July 2014 and December 2018. Patients were divided into two groups according to the surgical approach: TDA (34 cases) and SSDA (37 cases). The mean patient age was 78.6 years, and the mean (range) follow-up period was 23.5 (12-48) months. Clinical results were assessed using the Visual Analogue pain Scale (VAS), American Shoulder and Elbow Surgeon score (ASES), Korean Shoulder Scoring System (KSS), and Constant score. Radiographic indicators prosthesis-scapular neck angle (PSNA), peg-glenoid rim distance (PGRD), inferior overhang, acromion-greater tuberosity (AT) distance, and glenoid-greater tuberosity (GT) distance) were assessed, and notching severity was assessed according to the Nerot-Sirveaux classification.

The radiographic indicator results of the TDA and SSDA groups were as follows: PSNA (131.4° ± 17.2°, 136.1° ± 7.7°), PGRD (18.7 mm ± 2.9 mm, 21.4 mm ± 2.0 mm), AT distance (38.3 mm ±6.9 mm, 37.5 mm ± 6.8 mm), GT distance (51.6 mm ± 6.3 mm, 51.4 mm ± 5.3 mm), and inferior overhang (4.4 mm ± 2.2 mm, 2.9 mm ± 1.3 mm). PGRD and inferior overhang showed statistically significant differences between groups, but the clinical results showed no significant differences. There were no complications such as neurovascular injury, implant loosening, surgical site infection, or acromion fracture in either group.

SSDA for RSA showed no significant differences in clinical and radiological results compared with TDA. Therefore, SSDA is a viable alternative for RSA in cuff tear arthropathy.

This systematic review of the literature aims to analyse current knowledge to inform choice between hemiarthroplasty (HA) and reverse total shoulder arthroplasty (rTSA) for managing proximal humerus fractures (PHF) in elderly patients; the aim is to understand if rTSA can be considered the gold standard for treating PHF in the elderly when surgical fixation or conservative treatment is not viable options. Studies reporting outcomes and complications of PHF treated with shoulder arthroplasty in the elderly were included. Studies were in English and published after 2008. Evidence levels I, II, III and IV were included. According to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a comprehensive literature search was conducted using Medline, CINAHL (Cumulative Index to Nursing and Allied Health Literature) and PubMed search engines, as well as the Cochrane Central Register of Controlled Trials. General data collected were study design, number of patients treated with HA and rTSA, age of patients (mean, mean and SD, mean and range), length of follow-up, type of implant, and clinical outcomes. rTSA can be regarded as the gold standard for surgical management of displaced 3 and 4-part fractures in the elderly. However, the literature offers mostly low-quality studies, thereby requiring further work to achieve a full understanding of this important topic.

Reverse shoulder arthroplasty (RSA) was originally indicated for older adults, but outcomes in the oldest patients have not been studied. The purpose of this study was to report on patients aged ≥85 years undergoing RSA. We hypothesized that RSA would be safe, effective, and durable.

Sixty-one RSAs were performed in 58 patients aged ≥85 years (16 patients aged ≥90 years); 40 RSAs were performed for arthritis with cuff deficiency, 14 were performed for proximal humeral fractures, and 7 were performed as revisions. Active range of motion and patient-reported outcomes, comprising the American Shoulder and Elbow Surgeons score, Simple Shoulder Test score, and visual analog scale pain score, were obtained preoperatively and at final follow-up. Hospital length of stay, discharge disposition, and complications were recorded. Kaplan-Meier survivorship was computed with revision surgery or death as an endpoint.

The mean age at RSA was 88.0 years. Mean forward elevation improved from 50.5° to 105.3°; abduction, from 48.7° to 96.1°; and external rotation, from 10.2° to 26.9° (P < .001 for all). Similarly, at a mean follow-up of 2.4 years, the visual analog scale pain score improved from 6.1 to 0.6; Simple Shoulder Test score, from 2.2 to 7.0; and American Shoulder and Elbow Surgeons score, from 33.6 to 78.2 (P < .001 for all). The mean length of stay was 3.6 days, and 15 patients were discharged home. Seven patients received a blood transfusion, and only 2 patients underwent a reoperation, neither of whom required explantation.

Improvements in active range of motion and patient-reported outcomes in our patients were comparable to those observed in younger cohorts and exceeded published minimal clinically important differences for most patients undergoing RSA for cuff deficiency. Additionally, to date, the patients in our study who died had lived with their RSA for a mean of 3.4 years and living patients had lived with their RSA for a mean of 4.3 years. RSA in patients aged ≥85 years is safe, effective, and durable for their remaining life expectancy. This information may help counsel older patients who are considering RSA, electively or for fractures.

Primary reverse shoulder arthroplasty (rTSA) is an effective treatment option for reducing pain and improving function for patients with rotator cuff tear arthropathy, irreparable rotator cuff tears, glenoid deformity, and other challenging clinical scenarios, including fracture sequelae and revision shoulder arthroplasty. There has been a wide range of reported outcomes and postoperative complication rates reported in the literature. The purpose of this systematic review and meta-analysis is to provide an updated review of the clinical outcomes and complication rates following primary rTSA.

A systematic review and meta-analysis was performed to evaluate outcomes and complications following primary rTSA according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Demographics, range of motion, patient-reported outcome measures (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES] and Constant scores), number of complications, and revisions were extracted, recorded, and analyzed from the included articles.

Of the 1415 studies screened, 52 studies met the inclusion criteria comprising a total of 5824 shoulders. The mean age at the time of surgery was 72 years (range: 34-93), and the mean follow-up was 3.9 years (range: 2-16). Patients demonstrated a mean improvement of 56° in active flexion, 50° in active abduction, and 14° in active external rotation. Regarding functional outcome scores, rTSA patients demonstrated a mean clinically significant improvement of 37 in Constant score (minimal clinically important difference [MCID] = 5.7) and ASES score (42.0; MCID = 13.6). The overall complication rate for rTSA was 9.4% and revision rate of 2.6%. Complications were further subdivided into major medical complications (0.07%), shoulder- or surgical-related complications (5.3%), and infections (1.2%). The most frequently reported shoulder- or surgical-related complications were scapular notching (14.4%), periprosthetic fracture (0.8%), glenoid loosening (0.7%), and prosthetic dislocation (0.7%).

Primary rTSA is a safe and reliable procedure with low complication, revision, infection, and scapular notching rates. Additionally, patients demonstrated clinically significant improvements in both range of motion and clinical outcome scores.

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.

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).

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).

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.

The inverse total shoulder prosthesis is a standard treatment for cuff arthropathy. The number of implanted inverse total shoulder prostheses in Germany is significantly higher than that of the anatomical total shoulder prosthesis. Kaplan-Meier analyses show a 10-year result of inverse total shoulder prostheses after cuff arthropathy of 90%. The extent of the scapular notching correlates with the functional clinical outcome. The humeral anchoring principles of inverse total shoulder prosthesis differ considerably (from purely epiphyseal to diaphyseal). Inverse total shoulder prostheses show significant differences in humeral and glenoid offset as well as in shaft-neck angles. The large number of systems available differ considerably concerning anatomical and biomechanical parameters - the surgeons must be trained accordingly. Still, most shoulder replacements are implanted by surgeons who rarely perform this procedure.

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.