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Reverse shoulder arthroplasty (RSA) has become a widely used procedure since its introduction in the 1980s, and is currently used to treat a wider range of conditions than its original indication. The original Grammont-style RSA revolutionized shoulder arthroplasty but had several limitations, including scapular notching and reduced rotational motion. This review discusses the evolution of RSA design, particularly the development of a lateralized center of rotation constructs, which aims to improve all the disadvantages associated with the Grammont-style design and more closely reproduce the native anatomy in order to improve patient outcomes in an expanded context of pathologies. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to identify the demographic-, radiographic-, and surgery-related factors influencing postoperative functional internal rotation (fIR) following reverse total shoulder arthroplasty (RTSA). Methods: In this retrospective cohort study, patients who underwent RTSA between June 2013 and April 2018 at a single institution were assigned to two groups ("IROgood" or "IRObad"). Patients were classified as having good fIR (≥8 points in the Constant–Murley score (CS) and fIR to the twelfth thoracic vertebra or higher) or poor fIR (≤2 points in the CS and fIR to the twelfth thoracic vertebra or lower) after RTSA with a single implant model. The minimum follow-up period was two years. Standardized shoulder-specific scores (Visual Analogue Scale (VAS), Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons Score (ASES), Constant–Murley score (CS)) were used to assess the pre- and postoperative functional status of patients. Postoperative radiographic evaluation included the distalization shoulder angle (DSA), lateralization shoulder angle (LSA), critical shoulder angle (CSA), acromiohumeral distance (AHD), glenoid inclination (GI), medialization of the center of rotation (COR), lateralization of the humerus, and distalization of the greater tuberosity. Additionally, preoperative evaluation included rotator cuff arthropathy according to Hamada, glenoid version, anterior or posterior humeral head subluxation, and fatty infiltration of the rotator cuff according to Goutallier. Univariate analysis of demographic, surgical, radiographic, and implant-associated parameters was performed to identify factors associated with postoperative fIR. The Shapiro–Wilk test assessed the normal distribution of the data. Intergroup comparisons regarding demographic and surgery-related factors were conducted using the Mann–Whitney-U Test. Radiographic changes were compared using chi-square or Fisher's exact tests. The significance level was set at p < 0.05. Results: Of a total of 42 patients, 17 (age: 73.7 ± 5.0 years, follow-up (FU) 38 months [IQR 29.5–57.5]) were included in the "IRObad" group, and 25 (age: 72 ± 6.1 years, FU 47 months [IQR 30.5–65.5]) were included in the "IROgood" group. All patients were treated with the same type of implant (glenosphere size: 36 mm, 14.3%; 39 mm, 38.1%; 42 mm, 47.6%; neck-shaft angle: 135° in 68.0%; 155° in 32.0%) and had comparable indications. Univariate analysis did not reveal any of the investigated demographic, radiographic, or surgery-related parameters as risk factors for poor postoperative fIR (p > 0.05). Conclusion: None of the investigated factors, including implant-associated parameters, influenced postoperative fIR after RTSA in this cohort. [ABSTRACT FROM AUTHOR]

Background/Objectives: The aim of the study was to investigate the clinical, functional, and radiographic results of patients affected by three- or four-part proximal humeral fractures treated with reverse total shoulder arthroplasty, to investigate whether a prosthetic stem nonspecifically designed for fractures (i.e., the Bigliani-Flatow stem) promotes tuberosities' healing, and to evaluate the impact of tuberosity fixation and healing on the outcomes. Methods: Patients' data such as gender, age, side and dominancy, comorbidities, complications during or after surgery, and time lapse between trauma and surgery were prospectively collected. The type of fixation of the stem, the thickness and type of liner, and whether the tuberosities were fixed or not were also recorded. The Constant score weighted on the contralateral limb, QuickDASH, Oxford Shoulder Score, and Subjective Shoulder Value were collected. Tuberosities' healing was assessed with X-rays (anteroposterior, Grashey, and axillary views). Results: Overall, 34 patients were included, with an average follow-up of 42 months. Tuberosities were reinserted in 24 cases and their healing rate was 83%. The mean values were the following: a Constant score of 64, Oxford Shoulder Score of 39, Subjective Shoulder Value of 71, and QuickDASH score of 27. There were no significant differences in the scores or range of motion between patients with tuberosities healed, reabsorbed, or not reattached. There was a better external rotation in the group with healed tuberosities and a longer duration of surgery to reattach tuberosities. Conclusions: The treatment of proximal humerus fractures with the Bigliani-Flatow stem is associated with good clinical and functional results. The healing rate of the tuberosities was high and comparable, if not even better, than the mean rates reported for the stems dedicated to fractures of the proximal humerus and was, therefore, also appropriate for this indication. [ABSTRACT FROM AUTHOR]

Background: The optimal treatment for complex proximal humerus fractures (PHFs) lacks consensus, with reverse total shoulder arthroplasty (RTSA) often being a final resort rather than a primary approach. This study aimed to compare outcomes and satisfaction rates of primary RTSA for PHFs versus salvage RTSA for previously unsuccessful treatments. We hypothesized that primary RTSA would yield superior clinical outcomes, functional scores, and patient satisfaction. Methods: A retrospective analysis of RSA procedures between 2011 and 2021 was conducted, focusing on primary RTSA for PHFs or salvage RTSA for failed osteosynthesis. Patients meeting inclusion criteria underwent clinical and radiological follow-up for at least two years. Demographic characteristics, outcomes scores, and range of motion (ROM) were assessed. Results: Of 63 patients, 42 underwent primary RTSA and 21 underwent salvage RTSA. The median follow-up was 50 months. Statistically significant differences favored primary RTSA in forward flexion, abduction, internal rotation, and Constant shoulder score. Patient satisfaction levels did not significantly differ between groups. Complications occurred in 7.15% of primary RTSA cases and 14.28% of salvage RTSA cases. Conclusions: Primary RTSA may yield slightly better outcomes and lower complication rates compared to salvage RTSA. Further prospective studies are necessary to validate these findings. [ABSTRACT FROM AUTHOR]

Shoulder arthroplasty has significantly gained popularity in orthopedic surgery, driven by progress in prosthesis design and surgical techniques. This study explored the epidemiology of shoulder arthroplasty, analyzing healthcare data from 2012 to 2022 for primary osteoarthritis of the shoulder. The data included patient demographics and types of surgical procedures. Data analysis indicates a higher utilization rate of reverse total shoulder arthroplasty (RTSA; n = 41,251) over total- (TSA; n = 18,679) and hemiarthroplasty (HSA; n = 12,827) for primary shoulder osteoarthritis. Overall, a significant increase in RTSA procedures from n = 2237 (2012) to n = 5415 (2022) was observed, representing more than a two-fold increase of 121.1%. The relative proportion of RTSA among all types of shoulder arthroplasty increased from 39% (2012) to 68.6% (2022), while HSA decreased and TSA essentially remained constant. Age analysis identified the following peaks: RTSA, 77 ± 7 y; HSA, 68 ± 12 y; and TSA, 67 ± 10 y. Among the over 60s, significantly more women were treated with any type of prosthesis, whereas in young patients (45 to 59 y), more men received HSA or TSA. Our study confirms that RTSA has become the preferred choice for elderly patients in Germany, reflecting the prevailing preference despite varying patient ages and conditions, with a noted difference in sex in treatment prevalence. [ABSTRACT FROM AUTHOR]

Background: Despite the importance of the deltoid to shoulder biomechanics, very few studies have quantified the three-dimensional shape, size, or quality of the deltoid muscle, and no studies have correlated these measurements to clinical outcomes after anatomic (aTSA) and/or reverse (rTSA) total shoulder arthroplasty in any statistically/scientifically relevant manner. Methods: Preoperative computer tomography (CT) images from 1057 patients (585 female, 469 male; 799 primary rTSA and 258 primary aTSA) of a single platform shoulder arthroplasty prosthesis (Equinoxe; Exactech, Inc., Gainesville, FL) were analyzed in this study. A machine learning (ML) framework was used to segment the deltoid muscle for 1057 patients and quantify 15 different muscle characteristics, including volumetric (size, shape, etc.) and intensity-based Hounsfield (HU) measurements. These deltoid measurements were correlated to postoperative clinical outcomes and utilized as inputs to train/test ML algorithms used to predict postoperative outcomes at multiple postoperative timepoints (1 year, 2–3 years, and 3–5 years) for aTSA and rTSA. Results: Numerous deltoid muscle measurements were demonstrated to significantly vary with age, gender, prosthesis type, and CT image kernel; notably, normalized deltoid volume and deltoid fatty infiltration were demonstrated to be relevant to preoperative and postoperative clinical outcomes after aTSA and rTSA. Incorporating deltoid image data into the ML models improved clinical outcome prediction accuracy relative to ML algorithms without image data, particularly for the prediction of abduction and forward elevation after aTSA and rTSA. Analyzing ML feature importance facilitated rank-ordering of the deltoid image measurements relevant to aTSA and rTSA clinical outcomes. Specifically, we identified that deltoid shape flatness, normalized deltoid volume, deltoid voxel skewness, and deltoid shape sphericity were the most predictive image-based features used to predict clinical outcomes after aTSA and rTSA. Many of these deltoid measurements were found to be more predictive of aTSA and rTSA postoperative outcomes than patient demographic data, comorbidity data, and diagnosis data. Conclusions: While future work is required to further refine the ML models, which include additional shoulder muscles, like the rotator cuff, our results show promise that the developed ML framework can be used to evolve traditional CT-based preoperative planning software into an evidence-based ML clinical decision support tool. [ABSTRACT FROM AUTHOR]

After artificial joint surgery, bone density may decrease around the artificial joint; thus, postoperative bone density evaluation around the artificial joint is crucial. We investigated changes in bone mineral density and performed radiographic evaluation around the stem after reverse shoulder arthroplasty (RSA) surgery in 17 males (18 shoulders) and 19 females (19 shoulders), aged >65 years, with >1-year follow-up. In total, 20 and 17 cases involved massive rotator cuff tears and rotator cuff tear arthropathy, respectively. The Comprehensive Reverse Shoulder System (Standard Ingrowth) was used for all cases and cement was used in eight patients due to bone fragility. We examined lucent lines, loosening, bone resorption, and spot welds in non-cemented cases using plain radiography and postoperative bone density changes around the stem using dual-energy X-ray absorptiometry (DEXA). Lucent lines and bone resorption occurred in 5 (13.5%) and 19 (51.4%) shoulders, respectively. No loosening occurred. Compared to stem bone density at 2 weeks postoperatively, the decrease rate was the largest in the proximal medial humerus. One-year postoperative bone density was not related to sex, age, cement use, or preoperative diagnosis. Higher preoperative bone density was better maintained postoperatively. Furthermore, 1 year post RSA, spot welds were observed in approximately 48.2% of cases at the distal medial portion of the stem coating, and bone resorption occurred in the proximal medial humerus in 43.2% of cases. Therefore, postoperative bone density is related to preoperative bone density, suggesting the importance of maintaining high preoperative bone density. [ABSTRACT FROM AUTHOR]

(1) Background: The aim of the study was to evaluate the peak torque (PT) in isokinetic conditions and the range of motion of the shoulder joint in patients after reverse total shoulder arthroplasty in the late treatment period. (2) Methods: The study included fifteen patients aged 60–70 years (13 women and 2 men). The comparison group consisted of 15 healthy subjects (12 women and 3 men) aged 60–69 years. The study included measurement of peak torque (PT) and the range of motion of the shoulder joint, assessed using the Biodex System 4 Pro set, and an electronic goniometer. We conducted tests at two different angular velocities (60°/s and 90°/s), taking into account the operated and non-operated limb and comparing the results to healthy subjects. The average time from surgery to functional examination was 16 months. (3) Results: The non-operated limb generated significantly higher PT values than the operated limb (p < 0.001). The healthy limb of patients from the comparison group generated significantly higher PT values than the operated limb of patients from the study group (p < 0.001). A significant improvement (p < 0.001) in the range of motion in the operated limb was achieved after rTSA. (4) Conclusions: In patients 18 months after the rTSA, the non-operated upper limb has significantly greater muscle strength in flexion/extension and abduction/adduction movements compared to the operated limb. The non-operated limb also has a significantly greater range of motion compared to the operated limb. [ABSTRACT FROM AUTHOR]

Purpose: The success of reverse total shoulder arthroplasty (RTSA) has expanded its use for a broader range of shoulder indications worldwide. Evidence regarding the relative efficacy and long-term safety of medical technologies used in RTSA is subjected to rigorous assessment. Nonetheless, substantial challenges impede market access for innovative shoulder implant technologies for RTSA in Australia, resulting in delayed patient access. Approach: This paper addresses the key challenges associated with generating evidence for the health technology assessments of innovative medical technologies for RTSA that are required for access to the Australian market. The transition to value-based care requires establishing a benchmarking reference that incorporates patient-reported outcome measures (PROMs) and combines revision outcomes with additional clinical outcomes to increase patient cohort sizes. Establishing the benchmark would require agreement on the outcome measures to be collected for each indication, and investment in reporting patient-reported outcomes for RTSA to the national orthopaedic registry. Implications for practice: The need for increased flexibility in developing evidence for health technology assessment of RTSA medical technologies is required. Optimised approaches for benchmarking RTSA require extensive stakeholder discussions, including the agreement on evidence requirements and follow-up periods, selection of clinical outcomes, as well as preoperative and post-operative PROMs as a value assessment. [ABSTRACT FROM AUTHOR]

Ex vivo shoulder motion simulators are commonly used to study shoulder biomechanics but are often limited to performing simple planar motions at quasi-static speeds using control architectures that do not allow muscles to be deactivated. The purpose of this study was to develop an open-loop tendon excursion controller with iterative learning and independent muscle control to simulate complex multiplanar motion at functional speeds and allow for muscle deactivation. The simulator performed abduction/adduction, faceted circumduction, and abduction/adduction (subscapularis deactivation) using a cadaveric shoulder with an implanted reverse total shoulder prosthesis. Kinematic tracking accuracy and repeatability were assessed using maximum absolute error (MAE), root mean square error (RMSE), and average standard deviation (ASD). During abduction/adduction and faceted circumduction, the RMSE did not exceed 0.3, 0.7, and 0.8 degrees for elevation, plane of elevation, and axial rotation, respectively. During abduction/adduction, the ASD did not exceed 0.2 degrees. Abduction/adduction (subscapularis deactivation) resulted in a loss of internal rotation, which could not be restored at low elevation angles. This study presents a novel control architecture, which can accurately simulate complex glenohumeral motion. This simulator will be used as a testing platform to examine the effect of shoulder pathology, treatment, and rehabilitation on joint biomechanics during functional shoulder movements. [ABSTRACT FROM AUTHOR]

Background: With the increase in utility and popularity of the reverse total shoulder arthroplasty (RTSA) within the last decades, indications for RTSA have expanded. As well as the established indications such as cuff tear arthropathy and massive irreparable rotator cuff tears, RTSA for complex proximal humeral fractures in elderly patients has been proven to be a reliable treatment option. Methods: A prospectively enrolled RTSA database of 1457 RTSAs implanted between September 2005 and November 2020 was reviewed. Patients treated with RTSA for a complex proximal humerus fracture and fracture sequalae (F-RTSA) were 1:1 matched with a group of patients who were treated electively with RTSA for indications other than a fracture (E-RTSA). Matching criteria included sex, age, length of follow-up and body mass index. Evaluation after a minimum of 2 years follow-up included evaluation of the absolute and relative Constant–Murley score (aCS; rCS), subjective shoulder value (SSV), range of motion (ROM) assessment and complications. Results: Each of the matched cohorts comprised 134 patients with a mean follow-up of 58 ± 41 months for the fracture group and 58 ± 36 months for the elective group. The mean age for both groups was 69 ± 11 years in the F-RTSA and 70 ± 9 years for the E-RTSA group. There were no significant differences in clinical outcome measures including aCS, rCS and SSV (p > 0.05). There was a significant difference in mean active external rotation with 20° ± 18° in the F-RTSA group compared with 25° ± 19° in the E-RTSA group (p = 0.017). The complication rate was not significantly different, with 41 complications in 36 shoulders in the F-RTSA and 40 complications in 32 shoulders in the E-RTSA group (p = 0.73). The main complication for the F-RTSA group was dislocation of the greater tuberosity (6%), whereas acromial fractures (9%) were the leading complication in the E-RTSA group. There was also no significant difference in revision rate comparing F-RTSA with E-RTSA (10% vs. 14%; p = 0.25). Conclusions: RTSA for complex proximal humeral fractures and its sequalae leads to a comparable clinical outcome as that for patients treated electively with RTSA for indications other than fracture. There was, however, a significant difference in active external rotation, with inferior rotation in patients undergoing RTSA for fracture. This valuable information can help in requesting informed consent of patients with proximal humeral fractures. [ABSTRACT FROM AUTHOR]

The increased utilization of RTSA is also displayed in the statistics of the largest worldwide shoulder arthroplasty registry, the Australian Joint Replacement Registry, including over 60,000 shoulder replacements implanted in 2021, of which around 80% were RTSA [[21]]. The Evolution of Reverse Total Shoulder Arthroplasty - Where Do We Stand and What Comes Next? Keywords: reverse total shoulder arthroplasty; history; biomechanics; lateralization; implant design; mixed reality EN reverse total shoulder arthroplasty history biomechanics lateralization implant design mixed reality 1945 4 03/14/23 20230301 NES 230301 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 [[1]]. Reverse total shoulder arthroplasty, history, biomechanics, lateralization, implant design, mixed reality. [Extracted from the article]

Periprosthetic fractures, such as acromial and spine fractures, are known complications following implantation of reverse shoulder arthroplasty (RTSA). The entity of greater tuberosity fractures (GTF) has rarely been studied in the literature. The purpose of this study was to analyze the outcome of postoperative greater tuberosity fractures after RTSA compared to a matched control group. The main findings of this study are that a GTF after RTSA is associated with worse clinical outcome scores (mean absolute CS 50 ± 19 (p = 0.032); SSV 63% ± 26 (p = 0.022); mean force 1 kg ± 2 kg (p = 0.044)) compared with the control group (mean absolute CS 62 ± 21; SSV 77% ± 29; mean force 2 kg ± 2 kg). In terms of postoperative range of motion, the fracture group was significantly worse in terms of external rotation (17° ± 19° vs. 30° ± 19° (p = 0.029)). Internal rotation, flexion, as well as abduction of the shoulder appear to be unaffected (internal rotation GTF 4 ± 2, control group 5 ± 3 (p = 0.138); flexion GTF 102° ± 28°, control group 114° ± 27° (p = 0.160); abduction GTF 109° ± 42°, control group 120° ± 39° (p = 0.317)). [ABSTRACT FROM AUTHOR]

Reverse total shoulder arthroplasty presents itself sometimes as challenging when it comes to addressing massive bone loss, either in primary or revision settings. Custom components recently have made their way into shoulder prosthetics and are meant to help in the case of extensive glenoid bone destruction. Because of strict indication and the fairly recent introduction of these implants, the usage of custom-made glenoid implants is not very common yet. However, the early results are promising. The purpose of this review was to summarize and analyze the available literature. Therefore, a systematic review was performed according to PRISMA guidelines. A comprehensive search of the databases PubMed, Cochrane, and Livivo was performed to screen for studies reporting on clinical and radiological outcomes of custom glenoid implants. Four studies with a total of 46 shoulders were included in this review. The mean patient age was 68.8 years and the mean time of follow-up was 24.3 months. The weighted means showed an increase in CMS (32.7 points), in ASES (39.8 points), in anteversion (67.4 degrees), and in abduction (51.9 degrees) and a decrease in VAS (5.4 points). Custom-made glenoid implants are therefore a viable option in cases of large combined glenoid bone loss, both in primary and revision shoulder arthroplasty. [ABSTRACT FROM AUTHOR]

Fractures of the acromion and the scapular spine are established complications of reverse shoulder arthroplasty (RSA), and when they occur, the continuous strain by the deltoid along the bony fragments makes healing difficult. Evidence on treatment specific outcomes is poor, making the definition of a gold standard fixation technique difficult. The purpose of this systematic review is to assess whether any particular fixation construct offers improved clinical and/or radiographic outcomes. A systematic review of the literature on fixation of acromial and scapular spine fractures following RSA was carried out based on the guidelines of PRISMA. The search was conducted on PubMed, Embase, OVID Medline, and CENTRAL databases with strict inclusion and exclusion criteria applied. Methodological quality assessment of each included study was done using the modified Coleman methodology score to asses MQOE. Selection of the studies, data extraction and methodological quality assessment was carried out by two of the authors independently. Only clinical studies reporting on fixation of the aforementioned fractures were considered. Fixation construct, fracture union and time to union, shoulder function and complications were investigated. Nine studies reported on fixation strategies for acromial and scapular spine fractures and were therefore included. The 18 reported results related to fractures in 17 patients; 1 was classified as a Levy Type I fracture, 10 as a Levy Type II fracture and the remaining 7 fractures were defined as Levy Type III. The most frequent fixation construct in type II scapular spine fractures was a single plate (used in 6 of the 10 cases), whereas dual platin was the most used fixation for Levy Type III fractures (5 out of 7). Radiographic union was reported in 15 out of 18 fractures, whereas 1 patient (6.7%) had a confirmed non-union of a Levy Type III scapular spine fracture, requiring revision fixation. There were 5 complications reported, with 2 patients undergoing removal of metal and 1 patient undergoing revision fixation. The Subjective Shoulder Value and Visual Analogue Scale pain score averaged 75% and 2.6 points, respectively. The absolute Constant Score and the ASES score averaged 48.2 and 78.3 points, respectively. With the available data, it is not possible to define a gold standard surgical fixation but it seems that even when fracture union can be achieved, functional outcomes are moderate and there is an increased complication rate. Future studies are required to establish a gold standard fixation technique. [ABSTRACT FROM AUTHOR]

Proximal humerus fracture (PHF) is a common injury in the older population. While the majority of these fractures are treated non-operatively, a small subset of patients may benefit from surgical treatment. However, there continues to be an ongoing debate regarding the indications and ideal surgical treatment strategy. The use of reverse total shoulder arthroplasty (RTSA) has resulted in a paradigm shift in the treatment of PHFs in the older population. Unique biomechanical principles and design features of RTSA make it a suitable treatment option for PHFs in the older population. RTSA has distinct advantages over hemiarthroplasty and internal fixation and provides good pain relief and a reliable and reproducible improvement in functional outcomes. As a result, there has been an exponential increase in the volume of RTSA in the older population in last decade. The aim of this paper is to review the current concepts, outcomes and controversies regarding the use of RTSA for the treatment of PHFs in the older population. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the 50 most cited articles on shoulder arthroplasty (SA) and their characteristics. The Thomson ISIWeb of Science was searched with the following search terms: "shoulder arthroplasty", "shoulder replacement", "shoulder prosthesis" and "shoulder implant". All papers dealing with SA, including its perioperative and postoperative management, were included in this study. Citations ranged from 797 to 52 for the 50 highest cited papers on SA. According to absolute numbers, the top 10 papers were cited at least 118 times. Overall, 78% (n = 43) were clinical and the remaining articles were basic science research (one anatomic, six biomechanical). The most prevalent level of evidence was IV (72%). The Journal of Shoulder and Elbow Surgery published 40% of the studies. The majority of studies were conducted in the United States and eight other countries. The publication years of the most-cited articles ranged from 1991 to 2020, with the 2000s accounting for the most articles (96%) and the period from 2006 to 2010 with the absolute largest number of articles (17). This article provides a building block in the SA surgery. [ABSTRACT FROM AUTHOR]

Background: Acromial Levy III fractures after inverse shoulder arthroplasty occur in up to 7% of patients. To date, it is not clear how these fractures should be treated as clinical outcomes remain unsatisfactory. The aim of this study was to evaluate the biomechanical performance of three different plating methods of type III acromion fractures. Methods: Levy III fractures in synthetic scapulae were fixed with three different methods. Angular stable locking plates were placed on the spina scapula to bridge the fracture either dorsally, caudally, or on both aspects by double plating. In a biomechanical experiment, the pull of the deltoid muscle at 40° abduction of the arm was simulated by cyclic loading with increasing load levels until failure. Failure load, cycles to failure, and fragment motions were evaluated. Results: The results showed that double plating (350 ± 63 N) withstood the highest loads until failure, followed by dorsal (292 ± 20 N) and caudal (217 ± 49 N) plating. Similarly, double plating showed significantly smaller fragment movement than the other two groups. Conclusions: Double plating appeared to provide the largest biomechanical stability in type III acromion fracture under arm abduction. Caudal plating in contract resulted in insufficient fracture stability and early failure and can thus not be recommended from a biomechanical point of view. [ABSTRACT FROM AUTHOR]

Background. The indications for reverse shoulder arthroplasty (RSA) have been widely expanded, but only a few studies report the long-term survival of these implants. Our objective was to report the long-term survivorship of a large series of RSAs implanted for different etiologies. Methods. A retrospective multicenter study including all the RSAs was performed in six shoulder-specialized centers with at least 2 years of follow up. We reviewed 1611 RSAs, operated between 1993 and 2010, including 497 cuff-tear arthropathies (CTA), 239 revision RSAs, 188 massive cuff tears (MCT), 185 fracture sequelae (FS), 183 failed previous cuff repairs (FCR), and 142 primary osteoarthritis (POA). The mean follow-up was 5.6 ± 3.9 years (range 2–20). Results. Overall, 266 RSAs (16.5%) had at least one complication leading to 64 reoperations (4.0%) and 110 revision surgeries (6.8%). The most frequent complications were infection (3.8%), instability (2.8%), and humerus-related complications (2.8%). At 10 years, the survival without revision surgery was 91.0% in primary RSAs and 80.9% in revision RSAs for failed arthroplasty (p < 0.001). In the primary RSA group, MCT and FCR led to 10-year survivals for over 95% but fracture sequelae and tumors had the lowest 10-year survivals (83.9% and 53.1%). Younger patients had a lower 10-year survival. In revision RSAs, male patients had a significantly lower survival than females (72.3% vs. 84.5% at 10 years, p = 0.020). Discussion. Primary RSA for cuff-deficient shoulders or POA leads to a high 10-year survival, but revision RSA or primary RSA for FS and tumors are at high-risk for revision. Surgeons should be aware of high rates of complications and lower survival rates of RSA in younger patients, in males, and in RSAs for revision surgery. [ABSTRACT FROM AUTHOR]

Purpose of Review: The purpose of this review is to summarize recent literature regarding the latest design modifications and biomechanical evolutions of reverse total shoulder arthroplasty and their impact on postoperative outcomes. Recent findings: Over the past decade, worldwide implantation rates of reverse total shoulder arthroplasty have drastically increased for various shoulder pathologies. While Paul Grammont's design principles first published in 1985 for reverse total shoulder arthroplasty remained unchanged, several adjustments were made to address postoperative clinical and biomechanical challenges such as implant glenoid loosening, scapular notching, or limited range of motion in order to maximize functional outcomes and increase the longevity of reverse total shoulder arthroplasty. However, the adequate and stable fixation of prosthetic components can be challenging, especially in massive osteoarthritis with concomitant bone loss. To overcome such issues, surgical navigation and patient-specific instruments may be a viable tool to improve accurate prosthetic component positioning. Nevertheless, larger clinical series on the accuracy and possible complications of this novel technique are still missing. [ABSTRACT FROM AUTHOR]

The reverse total shoulder arthroplasty (rTSA) prosthesis has been demonstrated to be a viable treatment option for a variety of end-stage degenerative conditions of the shoulder. The clinical success of this prosthesis is at least partially due to its unique biomechanical advantages. As taught by Paul Grammont, the medialized center of rotation fixed-fulcrum prosthesis increases the deltoid abductor moment arm lengths and improves deltoid efficiency relative to the native shoulder. All modern reverse shoulder prostheses utilize this medialized center of rotation (CoR) design concept; however, some differences in outcomes and complications have been observed between rTSA prostheses. Such differences in outcomes can at least partially be explained by the impact of glenoid and humeral prosthesis design parameters, surgical technique, implant positioning, patient-specific bone morphology, and usage in humeral and glenoid bone loss situations on reverse shoulder biomechanics. Ultimately, a better understanding of the reverse shoulder biomechanical principles will guide future innovations and further improve clinical outcomes. [ABSTRACT FROM AUTHOR]

Load transfer through orthopaedic joint implants is poorly understood. The longer-term outcomes of these implants are just starting to be studied, making it imperative to monitor contact loads across the entire joint implant interface to elucidate the force transmission and distribution mechanisms exhibited by these implants in service. This study proposes and demonstrates the design, implementation, and characterization of a 3D-printed smart polymer sensor array using conductive polyaniline (PANI) structures embedded within a polymeric parent phase. The piezoresistive characteristics of PANI were investigated to characterize the sensing behaviour inherent to these embedded pressure sensor arrays, including the experimental determination of the stable response of PANI to continuous loading, stability throughout the course of loading and unloading cycles, and finally sensor repeatability and linearity in response to incremental loading cycles. This specially developed multi-material additive manufacturing process for PANI is shown be an attractive approach for the fabrication of implant components having embedded smart-polymer sensors, which could ultimately be employed for the measurement and analysis of joint loads in orthopaedic implants for in vitro testing. [ABSTRACT FROM AUTHOR]

Glenoid implant position and fixation are challenging in severe glenoid defects in reverse total shoulder arthroplasty (rTSA). Custom-made glenoid implants are metal augmented implants that are specially produced for a certain defect. They provide the restoration of the joint line and proper fixation. This retrospective data analysis investigated the clinical and radiological outcomes after revision using custom-made glenoid implants. Between 2018 and 2020, nine patients (10 shoulders) with severe glenoid defects underwent revision rTSA using a custom-made glenoid implant (Materialise Glenius or Lima ProMade). The pre- and postoperative Constant Murley Score (CMS), UCLA Score and Subjective Shoulder Value (SSV) were assessed. Postoperative CT scans and X-rays in two planes were available. The minimum follow-up was 12 months, with a mean follow-up of 23.1 months. The mean preoperative CMS, UCLA Score and SSV were 10.9, 4.1 and 11.0, respectively. The mean postoperative CMS, UCLA Score and SSV showed significant increases of 51.7 (<0.001), 22.9 (<0.001) and 52.0 (<0.001), respectively. There were no signs of loosening implants or scapular notching, and no revision was necessary. This trial showed promising clinical and radiological short-term outcomes for custom-made glenoid components in revision rTSA. [ABSTRACT FROM AUTHOR]

Background: Acromial and scapular spine fractures after reverse total shoulder arthroplasty (RTSA) can be devastating complications leading to substantial functional impairments. The purpose of this study was to review factors associated with increased acromial and scapular spine strain after RTSA from a biomechanical standpoint. Methods: A systematic review of the literature was conducted based on PRISMA guidelines. PubMed, Embase, OVID Medline, and CENTRAL databases were searched and strict inclusion and exclusion criteria were applied. Each article was assessed using the modified Downs and Black checklist to appraise the quality of included studies. Study selection, extraction of data, and assessment of methodological quality were carried out independently by two of the authors. Only biomechanical studies were considered. Results: Six biomechanical studies evaluated factors associated with increased acromial and scapular spine strain and stress. Significant increases in acromial and scapular spine strain were found with increasing lateralization of the glenosphere in four of the included studies. In two studies, glenosphere inferiorization consistently reduced acromial strain. The results concerning humeral lateralization were variable between four studies. Humeral component neck-shaft angle had no significant effect on acromial strain as analysed in one study. One study showed that scapular spine strain was significantly increased with a more posteriorly oriented acromion (55° vs. 43°; p < 0.001). Another study showed that the transection of the coracoacromial ligament increased scapular spine strain in all abduction angles (p < 0.05). Conclusions: Glenoid lateralization was consistently associated with increased acromial and scapular spine strain, whereas inferiorization of the glenosphere reduced strain in the biomechanical studies analysed in this systematic review. Humeral-sided lateralization may increase or decrease acromial or scapular spine strain. Independent of different design parameters, the transection of the coracoacromial ligament resulted in significantly increased strains and scapular spine strains were also increased when the acromion was more posteriorly oriented. The results found in this systematic review of biomechanical in-silico and in-vitro studies may help in the surgical planning of RTSA to mitigate complications associated with acromion and scapular spine fracture. [ABSTRACT FROM AUTHOR]

Background: Prosthesis selection, design, and placement in reverse total shoulder arthroplasty (RTSA) affect post-operative results. The aim of this systematic review was to evaluate the influence of the humeral stem version and prosthesis design (inlay vs. onlay) on shoulder function following RTSA. Methods: A systematic review of the literature on post-operative range of motion (ROM) and functional scores following RTSA with specifically known humeral stem implantations was performed using MEDLINE, Pubmed, and Embase databases, and the Cochrane Library. Functional scores included were Constant scores (CSs) and/or American Shoulder and Elbow Surgeons (ASES) scores. The patients were organised into three separate groups based on the implanted version of their humeral stem: (1) less than 20° of retroversion, (2) 20° of retroversion, and (3) greater than 20° of retroversion. Results: Data from 14 studies and a total of 1221 shoulders were eligible for analysis. Patients with a humeral stem implanted at 20° of retroversion had similar post-operative mean ASES (75.8 points) and absolute CS (68.1 points) compared to the group with humeral stems implanted at less than 20° of retroversion (76 points and 62.5 points; p = 0.956 and p = 0.153) and those implanted at more than 20° of retroversion (73.3 points; p = 0.682). Subjects with humeral stem retroversion at greater than 20° tended towards greater active forward elevation and external rotation compared with the group at 20° of retroversion (p = 0.462) and those with less than 20° of retroversion (p = 0.192). Patients with an onlay-type RTSA showed statistically significantly higher mean post-operative internal rotation compared to patients with inlay-type RTSA designs (p = 0.048). Other functional scores and forward elevation results favoured the onlay-types, but greater external rotation was seen in inlay-type RTSA designs (p = 0.382). Conclusions: Humeral stem implantation in RTSA at 20° of retroversion and greater appears to be associated with higher post-operative outcome scores and a greater range of motion when compared with a retroversion of less than 20°. Within these studies, onlay-type RTSA designs were associated with greater forward elevation but less external rotation when compared to inlay-type designs. However, none of the differences in outcome scores and range of motion between the humeral version groups were statistically significant. [ABSTRACT FROM AUTHOR]

Reverse total shoulder arthroplasty (RTSA) is increasingly used for the treatment of complex proximal humerus fractures and fracture sequelae. In 2021, half a dozen models of fracture stems are commercially available, reflecting its growing utility for fracture management. Prosthesis designs, bone grafting and tuberosity fixation techniques have evolved to allow better and more reliable fixation of tuberosities and bony ingrowth. Patients with anatomical tuberosity healing not only have an increased range of active anterior elevation and external rotation, but also experience fewer complications and longer prosthesis survival. This review provides an overview of recent evidence on basic and fracture-specific RTSA design features as well as tuberosity fixation techniques that can influence tuberosity healing. [ABSTRACT FROM AUTHOR]

Aims: The best surgical treatment of multi-fragmentary proximal humeral fractures in the elderly is a highly controversial topic. The aim of this study is to assess for sex-related differences regarding mortality and complications after reverse total shoulder arthroplasty (RTSA) and locking plate fixation (LPF). Patients and Methods: All patients from the largest German healthcare insurance (26.5 million policy holders) above the age of 65 years that were treated with LPF or RTSA after a multi-fragmentary proximal humerus fracture between January 2010 and September 2018 were included. Multivariable Cox regression models were used to assess the association of sex with overall survival, major adverse events and surgical complications. Results: A total of 8264 (15%) men and 45,707 (85%) women were followed up for a median time of 52 months. After 8 years, male patients showed significantly higher rates for death (65.8%; 95% CI 63.9–67.5% vs. 51.1%; 95% CI 50.3–51.9%; p < 0.001) and major adverse events (75.5%; 95% CI 73.8–77.1% vs. 61.7%; 95% CI 60.9–62.5%; p < 0.001). With regard to surgical complications, after adjustment of patient risk profiles, there were no differences between females and males after LPF (p > 0.05), whereas men showed a significantly increased risk after RTSA (HR 1.86; 95% CI 1.56–2.22; p < 0.001) with more revision surgeries performed (HR 1.76, 95% CI 1.46–2.12; p < 0.001) compared to women. Conclusion: The male sex is an independent risk factor for death and major adverse events after both LPF and RTSA. An increased risk for surgical complications after RTSA suggests that male patients benefit more from LPF. Sex should be considered before making treatment decisions. [ABSTRACT FROM AUTHOR]

Previous attempts to measure lateralization, distalization or inclination after reverse total shoulder arthroplasty (rTSA) and to correlate them with clinical outcomes have been made in the past years. However, this is considered to be too demanding and challenging for daily clinical practice. Additionally, the reported findings were obtained from heterogeneous rTSA cohorts using 145° and 155° designs and are limited in external validity. The purpose of this study was to investigate the prognostic preoperative and postoperative radiographic factors affecting clinical outcomes in patients following rTSA using a 135° prosthesis design. In a multi-center design, patients undergoing primary rTSA using a 135° design were included. Radiographic analysis included center of rotation (COR), acromiohumeral distance (AHD), lateral humeral offset (LHO), distalization shoulder angle (DSA), lateralization shoulder angle (LSA), critical shoulder angle (CSA), and glenoid and baseplate inclination. Radiographic measurements were correlated to clinical and functional outcomes, including the American Shoulder and Elbow Surgeons (ASES), Simple Shoulder Test (STT), Single Assessment Numeric Evaluation (SANE), and Visual Analogue Scale (VAS) score, active forward elevation (AFE), external rotation (AER), and abduction (AABD), at a minimum 2-year follow-up. There was a significant correlation between both DSA (r = 0.299; p = 0.020) and LSA (r = −0.276; p = 0.033) and the degree of AFE at final follow-up. However, no correlation between DSA (r = 0.133; p = 0.317) and LSA (r = −0.096; p = 0.471) and AER was observed. Postoperative AHD demonstrated a significant correlation with final AFE (r = 0.398; p = 0.002) and SST (r = 0.293; p = 0.025). Further, postoperative LHO showed a significant correlation with ASES (r = −0.281; p = 0.030) and LSA showed a significant correlation with ASES (r = −0.327; p = 0.011), SANE (r = −0.308, p = 0.012), SST (r = −0.410; p = 0.001), and VAS (r = 0.272; p = 0.034) at terminal follow-up. All other correlations were found to be non-significant (p > 0.05, respectively). Negligible correlations between pre- and postoperative radiographic measurements and clinical outcomes following primary rTSA using a 135° prosthesis design were demonstrated; however, these observations are of limited predictive value for outcomes following rTSA. Subsequently, there remains a debate regarding the ideal placement of the components during rTSA to most sufficiently restore active ROM while minimizing complications such as component loosening and scapular notching. Additionally, as the data from this study show, there is still a considerable lack of data in assessing radiographic prosthesis positioning in correlation to clinical outcomes. As such, the importance of radiographic measurements and their correlation with clinical and functional outcomes following rTSA may be limited. [ABSTRACT FROM AUTHOR]