Use of computed tomography for shoulder arthroplasty: A systematic review.

Introduction: The prevalence of total shoulder arthroplasties is on the rise annually. Improvements in implant quality, construct stability, and surgical techniques have notably enhanced post-operative results, prompting an expansion of indications for shoulder arthroplasty. Despite its high success rate, opportunities for enhancement remain, especially in preoperative planning and intraoperative execution. Advanced imaging technologies offer significant potential in optimizing implant placement, thus improving the longevity of the procedure. To our knowledge, a comprehensive review examining the impact of advanced imaging on shoulder arthroplasty has yet to be conducted. This systematic review aims to investigate the benefits of advanced imaging technologies in this context, focusing on their application in preoperative planning, osteoarthritis assessment, intraoperative adjustments, patient-specific instrumentation, and navigational aids. Methods: This review utilized a comprehensive search of PubMed to identify relevant studies published from 2000 to 2024, focusing on the application of various imaging techniques in shoulder arthroplasty. The search was conducted by two authors and centered on plain radiography, CT scans, and MRI. The selection criteria included availability of full-text articles, English language, direct comparison of imaging techniques, and a focus on patient outcomes, including discussions on broader applications such as intraoperative navigation and patient-specific instrumentation development. Results: Enhanced imaging techniques, particularly CT scans and MRIs, have been shown to significantly improve outcomes in shoulder arthroplasty. While plain radiographs remain standard, CT scans provide superior bony detail, crucial for evaluating glenoid wear and determining augmentation needs. Preoperative CT imaging has been demonstrated to enhance implant placement accuracy. Moreover, intraoperative technologies based on CT imaging, such as patient-specific instrumentation and navigation systems, contribute to better surgical results. Conclusion: The benefits of CT imaging in shoulder arthroplasty significantly outweigh the associated costs. Current literature strongly supports the adoption of CT imaging in these procedures, particularly when used alongside modern operative technologies.

Modified notching classification in inverted-bearing and conventional-bearing reverse total shoulder arthroplasty.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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 OF EVIDENCE: Level 4, Case Series, Treatment Study.

Finding the Truth: Cadaver and CT scan Study of Differences in Glenoid Width Size in the Indian Population.

Introduction: Glenoid mass issues have been extensively published in the recent literature. The controversy arose from our need to compare and obtain the appropriate implant size for reverse shoulder arthroplasty patients. Some well-known authors and surgeons say that Indian patients have a smaller glenoid than their Western friends and patients. Therefore, we decided to examine the glenoid size obtained on a computed tomography (CT) scan and the size obtained on a cadaver, preferably the same cadaver in tertiary care medical school. Necessary permissions were obtained from the relatives of the cadaver, the ethical board, the anatomy department, and the radiology department. Materials and Methods: We evaluated 3D CT scans of 100 patients from our medical college during the global pandemic. Of these, we evaluated only 12 patients whose families agreed to postmortem studies and CT scans. Our research focuses on the shoulder of non-orthopedic diseases conducted at KCGMCH and measured the glenoid height, width, and version using a commercially available computer. Results: The mean age of the patients was 38.5 (range 19-59). The mean glenoid height was 33.8 ± 3.2 mm, maximum glenoid width was 24.3 ± 2.2 mm. The mean glenoid version is 3.48 ± 4 retrospectively. The glenoid width appears to be 23-25 mm on CT scan film, which is similar to cadaver studies. Conclusion: The findings from the cadaver study indicate that the average glenoid size is smaller in the Indian demographic when compared to CT scans. Glenoid width is less in one subset of the population, especially female patients than of the average population than Westerners. However, our studies are limited by the small size of the population and a larger study is recommended in our institution in the future. A better understanding of this glenoid size could help us design a smaller glenoid plate plan, especially for patients in the Indian subcontinent.

A reduced scapulo-humeral angle contributes to the development of scapular notching in reverse total shoulder arthroplasty.

PURPOSE: Scapular Notching (SN) is one of the most common postoperative complications for a patient after Reverse Total Shoulder Arthroplasty (RTSA). Despite employing various strategies to mitigate SN risk, the overall incidence remains far from zero. This article introduces a new risk factor, the scapulo-humeral angle (SHA), as a key element influencing the risk for SN. METHODS: A retrospective analysis was conducted on all patients who underwent RTSA for rotator cuff arthropathy at the study centre. The preoperative SHA was measured, and the presence of SN was investigated and graded using the Nerot classification at the latest follow-up. RESULTS: 42 patients were included. 12 presented SN (incidence 28.5%). A statistically significant Pearson coefficient correlation between pre-operative SHA and the incidence of SN was observed (r= -0.6954; 95% C.I. -0,8250 to -0,4963; p < 0.0001). A statistically significant Pearson coefficient correlation was also found between the degree of SN and the pre-operative SHA (r= -0,7045; 95% C.I. -0,8306 to -0,5096; P value (two-tailed) < 0,0001, alpha 0.05). CONCLUSIONS: The primary finding is a statistically significant correlation between a reduced preoperative SHA and an increased incidence of postoperative SN. The secondary finding is that a smaller preoperative SHA is associated with a more severe degree of SN A SHA cut-off of 50° distinguished patients at high risk of SN from those at low risk. All patients with an SHA below 50° developed SN (10/10), whereas only 6.25% of patients with an SHA exceeding 50° experienced SN (2/32).

Complications after Reverse Total Shoulder Arthroplasty in the Korean Population: A Single Center Study of 299 Cases.

BACKGROUND: Knowledge regarding differences in the order of frequency of complications after reverse total shoulder arthroplasty (RTSA) between Asian and Western populations is limited. We therefore asked for (1) What is the order of frequency of complications after primary RTSA in the Korean population? (2) What are the rates of complication, reoperation, and revision, and clinical outcomes after index surgery? METHODS: We retrospectively reviewed the 299 consecutive cases who underwent primary RTSA with more than 1 year of follow-up over a period of 12 years. The mean age of the patients was 73.4 years (range, 58-88 years) and the mean follow-up period was 3.8 years (range, 1-11.5 years). Evaluation of the clinical outcomes, complications, and reinterventions was performed at the final follow-up. RESULTS: The mean VAS pain score, UCLA score, ASES score, and SSV improved from 6.7, 10.2, 30.7, and 27.7% before RTSA to 1.4, 26.4, 80.5, 77.2% after RTSA, respectively (P < .001). Overall, 45 complications (15.1%) were observed in 44 patients. The order of frequency of complications was as follows: 16 cases of scapular stress fracture (5.4%), 9 intraoperative or postoperative periprosthetic fracture (3.0%), 6 brachial plexus injury (2.0%), 4 instability (1.3%), 2 glenoid loosening (0.7%), 2 glenoid disassembly (0.7%), 2 periprosthetic joint infection (0.7%), 1 glenoid fixation failure (0.3%), 1 humeral stem fixation failure (0.3%), 1 hematoma (0.3%), and 1 complex regional pain syndrome (0.3%). Reintervention was performed in 15 cases (5.0%) including reoperation (8 cases; 2.7%) and revision surgery (7 cases; 2.3%). CONCLUSION: At a mean follow-up period of 3.8 years, primary RTSA showed satisfactory clinical outcomes with a complication rate of 15.1%, a reoperation rate of 2.7%, and a revision rate of 2.3%. Scapular stress fracture appears to be the most common complication after RTSA in the Korean population.

Anatomic restoration of lateral humeral offset and humeral retroversion optimizes functional outcomes following reverse total shoulder arthroplasty.

Cadaveric and computer simulations suggest lateral humeral offset (LHO) and humeral retroversion (HR) are associated with strength and range of motion (ROM) after reverse total shoulder arthroplasty (rTSA), butin vivodata is lacking. This study aimed to evaluate the effects of implant parameters (i.e. LHO and HR) on strength and ROM. LHO and HR were measured using pre-operative and post-operative computed tomography (CT) scans. Postoperative strength was measured across three planes of motion using a Biodex isokinetic dynamometer. Postoperative active and passive ROM during forward elevation, external rotation (ER), and internal rotation (IR) were assessed using a goniometer or spinal level. 30 rTSA patients (14 M, 16F, age: 71.8 ± 6.7yrs) participated with an average postoperative follow-up of 2.4 ± 1.1 years. Regarding strength, higher post-op LHO values were predictive of greater postoperative strength across all movements. However, lateralization of the implant beyond pre-op values (i.e. post-op LHO > pre-op LHO) was associated with poorer strength performance across all ranges of motion. Similar to strength outcomes, greater deviations from pre-op LHO was predictive of poorer IR ROM. Lastly, patients with minimal deviations in HR (post-op HR within 10° of pre-op HR) and minimal deviations in LHO (post-op LHO ≤ pre-op LHO) displayed the greatest postoperative ER ROM. Anatomic restoration of LHO combined with anatomic restoration of HR may be ideal for maximizing strength and ROM following rTSA. Overlateralization beyond anatomic may have negative consequences. Optimal implant lateralization and version may need to be individualized based on preoperative values.

Appropriateness of Prior Authorization Requirements for Total Shoulder Arthroplasty: A Systematic Review.

INTRODUCTION: Total shoulder arthroplasty (TSA) has become increasingly utilized for managing glenohumeral osteoarthritis (GHOA), with procedure rates expected to rise. Consequently, there has been a surge in prior authorization (PA) requests for TSA, imposing a substantial administrative burden and highlighting the need for physician advocates to challenge the current PA system. A notable PA requirement is preoperative physical therapy (PT), a treatment modality for GHOA that has not been extensively studied and is not endorsed by the American Academy of Orthopedic Surgery (AAOS) as necessary for the treatment for GHOA. METHODS: We conducted a systematic literature search using PubMed, Embase, and Medline, adhering to PRISMA guidelines. Our search focused on studies with level IV evidence or higher that examined the efficacy preoperative PT for patients with GHOA. RESULTS: We found 210 studies of which three met our inclusion criteria. Our results were mixed, with two of the three studies supporting the use of preoperative PT. Only one study employed a randomized controlled trial (RCT) design, underscoring the need for more high-quality studies in this area. DISCUSSION/CONCLUSION: Our findings suggest that there is limited evidence for the benefit of preoperative PT in GHOA. This contradicts the current PA requirements which require patients to undergo preoperative PT to receive coverage for treatment. This review highlights the need for physician engagement in advocacy efforts to challenge these current requirements and improve patient care.

Survivorship and Clinical Outcomes of Reverse Total Shoulder Arthroplasty in Patients with Large Glenoid Defects Using the Stilting Technique and a Baseplate with Central Ingrowth Cage and Peripheral Locking Screws.

BACKGROUND: Stilting is a novel technique used in reverse shoulder arthroplasty (RSA) in patients with significant glenoid bone loss. This technique utilizes peripheral locking screws placed behind an unseated portion of the baseplate, to transmit forces from the baseplate to the cortical surface of the glenoid, without the need for bone grafting. The stilted screw, once locked, provides a fixed angle point of support for an unseated aspect of a baseplate. The primary advantages of this technique are reduced cost compared to a custom implant and reduced operative time compared to bone grafting. METHODS: We conducted a retrospective, non-randomized, comparative cohort study of 41 patients underwent primary Reverse Shoulder Arthroplasty (RSA) using the Stilting Technique with the Exactech Equinoxe Reverse System (Gainesville, FL, USA) at a single, academic center from the years 2004-2021. Exclusion criteria included age under 18 or over 100, and oncologic or acute fracture RSA indications. Operative data was documented, including implant records, percent baseplate seating, and operative duration. Survivorship was compared among primary stilted-RSA (n=41), bone graft-RSA (n=42), and non-stilted/non-bone grafted RSA (n=1,032) within our institutional shoulder arthroplasty database. A radiographic examination of baseplate failure was also conducted across the study groups. Postoperative functional outcomes were compared in a matched analysis involving patients with a minimum 2-year follow-up between stilted patients and a non-stilted/non-bone grafted control group for primary RSA. RESULTS: All Stilted-RSA cases utilized metal augments and demonstrated a mean baseplate seating of 61% (range 45-75%). For stilted RSAs, survivorship was 100% and 92.6% at 2- and 5-years, compared to 98.3% and 94.6% for non-stilted/non-bone grafted and 96.3% and 79.5% for bone-grafted RSAs (p=0.042). At 5-years, the baseplate-related failure rates were greater in the stilted (7.4%) and the bone-grafted (9.3%) cohorts compared with the non-stilted/non-bone grafted cohort (1.1%, p<0.001). The mean time to baseplate failure was 30 months for stilted RSA. Functional outcomes for primary RSA were statistically similar between stilted and non-stilted patients, including range of motion, Constant, ASES, SST, UCLA, and SPADI scores. CONCLUSION: The stilted-RSA cohort exhibited noninferior revision and baseplate failure rates to that of bone-grafted RSA. This suggests that stilting may be a viable technique for patients undergoing primary RSA with significant glenoid deformity.

Revision Shoulder Arthroplasty: Predictors of Subsequent Revision Surgery and Economic Burden amongst Medicare Beneficiaries.

BACKGROUND: Revision shoulder arthroplasty continues to add an increasing burden on patients and the healthcare system. This study aimed to delineate long-term shoulder arthroplasty revision incidence, quantify associated Medicare spending, and identify relevant predictors of both revision and spending. METHODS: The complete 2016-2022(Q3) Medicare fee-for-service inpatient and outpatient claims data was analyzed. Patients receiving a primary total shoulder arthroplasty for osteoarthritis, rotator cuff pathology, or inflammatory arthropathy were included and subsequent ipsilateral revision surgeries were identified. The time to revision was modeled using the Prentice, Williams, and Peterson Gap Time Model. Medicare spending within 90 days post-discharge was modeled using a generalized linear model. The analysis was subdivided by index procedure type: anatomic total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA). RESULTS: A total of 82,949 primary TSAs and 172,524 RSAs were identified. Compared to index TSA cases, index RSA cases had a lower first revision rate in an observation window of nearly 7 years (1.9% vs. 3.5%, p<0.001), but a higher rate of second (11.4% vs. 4.9%, p<0.001) as well as third revision (13.8% vs. 13.8%, p=0.449). TSA spending was significantly lower than RSA spending for the index procedure ($21,531 vs. $23,267, p<0.001), first ($23,096 vs. $26,414, p<0.001), and second ($25,060 vs. $29,983, p<0.001) revision. There was no statistically significant difference in third revision between TSA and RSA groups ($31,313 vs. $30,829, p=0.860). Age, sex, race, and rheumatoid arthritis were among the top predictors of revisions. Top predictors of Medicare spending included having a non-osteoarthritis surgical indication, a hospital stay of three or more days, a discharge to a setting other than home, malnutrition, dementia, stroke, major kidney diseases, and being operated on in a teaching hospital. CONCLUSION: Compared with TSA, RSA was associated with a lower first revision rate, but a higher subsequent revision rate. An index RSA procedure was also associated with higher initial Medicare spending as well as subsequent revision surgery spending compared with an index TSA procedure. Demographics and comorbid medical conditions were among the top predictors of revisions, while procedure-related factors predicted Medicare spending.

An in vitro study of glenoid implant peripheral peg interface mechanics during eccentric loading and lift-off.

Glenoid implants used in anatomic total shoulder arthroplasties typically incorporate peripheral pegs as a design feature to support eccentric loads. These peripheral pegs and the implant-cement-bone interface undergo substantial cyclic tensile-compressive loads during normal activity. Therefore, these pegs are of interest in translating the micromechanics of local implant fixation failure to the biomechanics of gross anatomic failure of the glenoid implant after total shoulder arthroplasty. This study used an in vitro peg-cement-bone construct which incorporated bone tissue acquired from osteoarthritic patients undergoing total shoulder arthroplasty. Strain distributions in the peripheral peg-cement-bone interfaces were analyzed under loading conditions emulating glenoid implant edge displacements. It was found that tensile strains in the interfaces were highest near the backside-peg junction and were greater in magnitude than compressive strains. Notably, strains near the peg's fixation channels were relatively low. These results suggest that cracks may initiate around the peg near the backside and travel downward to cause broader fixation failure.

Predicting Unplanned Return to Operating Room Following Primary Total Shoulder Arthroplasty: Insights from Fair and Explainable Ensemble Machine Learning.

Reoperation is the most significant complication following any surgical procedure. Developing machine learning methods that predict the need for reoperation will allow for improved shared surgical decision making and patient-specific and preoperative optimisation. Yet, no precise machine learning models have been published to perform well in predicting the need for reoperation within 30 days following primary total shoulder arthroplasty (TSA). This study aimed to build, train, and evaluate a fair (unbiased) and explainable ensemble machine learning method that predicts return to the operating room following primary TSA with an accuracy of 0.852 and AUC of 0.91.

Clinical and radiological results of the SIMPLICITI* stemless shoulder arthroplasty: a twenty five patients retrospective cohort.

PURPOSE: For preserving the humeral bone stock, some surgeons proposed a stemless humeral prosthetic component. This study reports the functional and radiologic results of the stemless anatomic prosthesis Simpliciti*(Tornier, Wright, Stryker), with the hypothesis that it can achieve a good metaphyseal fixation. METHODS: 28 patients underwent 30 shoulder replacements with the Simpliciti* humeral prosthesis followed for an average of three years (2 months to 8 years). The clinical outcome used the Constant-Murley score and the Bankes resistance and force evaluation. The radiologic assessment looked after radiolucent lines, signs of implant migration, osteolysis or loosening. RESULTS: The Constant score improved from 19.03 preoperatively to 54.03 points post operatively. Radiographic analysis showed one early component loosening, and at the longer follow-up, one radiolucent line. All the other implants appeared well fixed. CONCLUSION: This study verified the quality of the metaphyseal fixation of this stemless implant, with achieving a significant functional improvement. LEVEL OF EVIDENCE: Level IV, Case Series, Treatment Study.

Reverse Allograft Prosthetic-Composite Versus Endoprosthesis Reconstruction for Massive Proximal Humerus Bone Loss: A Systematic Review and Meta-analysis of Outcomes and Complications.

Background: This systematic review and meta-analysis sought to compare the clinical outcomes after proximal humerus reconstruction with a reverse allograft-prosthetic composite (APC) versus reverse endoprosthesis. Methods: Per PRISMA guidelines, we queried PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify articles reporting clinical outcomes of reverse APC or reverse endoprosthesis reconstruction of the proximal humerus for massive bone loss secondary to tumor, fracture, or failed arthroplasty. We compared postoperative range of motion, outcome scores, and the incidence of complications and revision surgery. Results: Of 259 unique articles, 18 articles were included (267 APC, 260 endoprosthesis). There were no significant differences between the APC and endoprosthesis cohort for postoperative forward elevation (P = .231), external rotation (P = .634), ASES score (P = .420), Constant score (P = .414), MSTS (P = .815), SST (P = .367), or VAS (P = .714). Rate of complications was 15% (31/213) in the APC cohort and 19% (27/144) in the endoprosthesis cohort. The rate of revision surgery was 12% after APC cohort and 7% after endoprosthesis. APC-specific complications included a 10% APC nonunion/malunion/resorption rate and 6% APC fracture/fragmentation rate. Discussion: Reverse APC and endoprosthesis are reasonable options for proximal humerus reconstruction. APC carries additional risks for complications, warranting evaluation of patients' healing capacity and surgeon experience. Level of Evidence: Level IV; Systematic Review. Supplementary Information: The online version contains supplementary material available at 10.1007/s43465-024-01248-7.

Non-union of the greater tuberosity in patients undergoing reverse total shoulder arthroplasty for proximal humerus fracture: Is it associated with worse outcomes?

BACKGROUND: 4-part proximal humerus fractures are complex injuries that are often associated with comminution of the greater tuberosity. The purpose of this study is to evaluate the functional outcomes of 4-part humerus fractures that are treated with reverse total shoulder arthroplasty (rTSA) and correlate these outcomes with the healing status of the greater tuberosity. MATERIAL AND METHODS: A retrospective observational study was performed including 65 patients who underwent rTSA following a 4-part proximal humerus fracture. These patients were categorized into 3 groups according to the healing status of the greater tuberosity: patients with healed greater tuberosity in an anatomical position (group A, n = 43), patients with non-union of the greater tuberosity but in anatomical position (group B, n = 14), and patients with resorption or non-union of the greater tuberosity not in anatomical position (group C, n = 8). The Constant-Murley score and range of motion were recorded for each patient at 12 months postoperatively. The clinical and radiographical outcomes of the 3 groups were compared. RESULTS: Patients with healed greater tuberosity (group A) had higher range of motion compared to patients with greater tuberosity migration or reabsorption (group C) regarding forward flexion (130° vs 80°, p < 0.001), abduction (110° vs 65°, p < 0.001) and external rotation (20° vs 10°, p = 0.004). However, no significant changes regarding forward flexion (130° vs 125°, p = 0.67), abduction (110° vs 100°, p = 0.60) and external rotation (20° vs 25°, p = 0.37) were noted between patients with healed greater tuberosity (group A) and those with non-united greater tuberosity that remained attached to the humeral prosthesis (group B). Similarly, Constant- Murley score was similar between patients of group A and group B (65.0 vs 61.5, p = 0.53), while it was higher in patients of group A compared to those of group C (65.0 vs 39.0, p = 0.053). CONCLUSIONS: The outcomes of this study indicate that reliable recovery regarding range of motion and functional status can be achieved in patients who undergo rTSA due to 4-part proximal humerus fractures, as long as the greater tuberosity remains in close proximity to the humeral prosthesis, even if it has signs of non-union with no continuity to the adjacent humerus.

Greater distance from the glenosphere center to the acromion reduces risk of acromial impingement in semi-inlay reverse shoulder arthroplasty.

Background: Recently, the issue of subacromial notching, caused by acromial impingement has been reported. The purpose of this study was to assess the impact of differences in the distance between the glenosphere center and the greater tuberosity (DGT) and the distance between the glenosphere center and the acromion (DA) on the closest distance between the greater tuberosity and the acromion during active abduction in shoulders with reverse total shoulder arthroplasty (RSA). Methods: Eleven shoulders with semiinlay RSA were analyzed. Subjects underwent fluoroscopy during active scapular plane abduction. Computed tomography of their shoulders was performed to create three-dimensional (3D) implant models at a mean of 16 months after surgery. Using model-image registration techniques, poses of 3D implant models were iteratively adjusted to match their silhouettes with the silhouettes in the fluoroscopic images (shape matching), and 3D kinematics of implants were computed. The closest distance between the acromion and greater tuberosity was computed at maximum abduction. DA and DGT were measured from 3D surface models. Shoulders were divided into two groups based on DA and DGT measurements and their closest distance data were compared between the groups. Results: There were 7 shoulders with DA ≥ DGT, and 4 shoulders with DA < DGT. Shoulders with DA ≥ DGT showed a significantly wider distance between the greater tuberosity and acromion at maximum abduction compared to those with DA < DGT (5.9 ± 2.4 mm vs. 0.6 ± 0.7 mm, respectively, P = .0021). There were no significant differences in maximum glenohumeral abduction angle and humeral abduction angle between the two groups. Although DA was significantly greater in shoulders with DA ≥ DGT than in those with DA < DGT (43.7 ± 4.4 mm vs. 35.1 ± 6.7 mm, respectively, P = .0275), there was no significant difference in DGT between the two groups. Conclusion: When DGT is less than DA in shoulders with RSA, the closest distance between the greater tuberosity and the acromion at maximum abduction is significantly wider compared to cases where DGT is greater than DA by 3D measurement. Therefore, acromial impingement is less likely to occur in shoulders with RSA when DA is greater than DGT. To avoid acromial impingement, it might be important to make DA greater than DGT.

Reverse shoulder arthroplasty with an inverted-bearing prosthesis as revision procedure for failed anatomic and reverse shoulder arthroplasty: a long-term multicenter study.

Background: Despite the increasing use of revision reverse total shoulder arthroplasty (RTSA), studies directly comparing revision RTSA performed for different failed index procedures are limited. We therefore compared the results of revision RTSA between patients with a failed primary anatomic arthroplasty (total shoulder arthroplasty and hemiarthroplasty) and those with a failed primary RTSA to explore revision of which index procedure resulted in better long-term clinical outcomes. Methods: In this prospective, multicenter, observational study, patients underwent revision RTSA using an inverted-bearing prosthesis. We recorded clinical scores, active range of motion, pain, satisfaction, and the rate of scapular notching. Complications and prosthesis survival were also noted. Results: We included 45 patients (45 shoulders) with revision RTSA for failed primary anatomic shoulder arthroplasty (30 patients) and RTSA (15 patients). Clinical and radiographic outcomes were recorded from 36 patients at a median follow-up of 101.6 months, and prosthesis survival was assessed from all 45 patients. At final follow-up, clinical scores (P < .05), abduction (P = .032), re-revision rate (P = .018), and prosthesis survival (P = .015) were significantly better in patients revised from failed primary anatomic shoulder arthroplasty than those from RTSA. However, pain, satisfaction, and overall complication rates were similar in both groups (P > .05). Conclusions: We found better long-term clinical scores, abduction, and prosthesis survival rates after failed primary anatomic shoulder arthroplasty than after RTSA. Pain reduction and complication rates were comparable in both groups. Thus, anatomic shoulder arthroplasty remains an attractive option for primary arthroplasty in selected cases.

Can ChatGPT answer patient questions regarding reverse shoulder arthroplasty?

INTRODUCTION: In recent years, artificial intelligence (AI) has seen substantial progress in its utilization, with Chat Generated Pre-Trained Transformer (ChatGPT) is emerging as a popular language model. The purpose of this study was to test the accuracy and reliability of ChatGPT's responses to frequently asked questions (FAQ) pertaining to reverse shoulder arthroplasty (RSA). METHODS: The ten most common FAQs were queried from institution patient education websites. These ten questions were then input into the chatbot during a single session without additional contextual information. The responses were then critically analyzed by two orthopedic surgeons for clarity, accuracy, and the quality of evidence-based information using The Journal of the American Medical Association (JAMA) Benchmark criteria and the DISCERN score. The readability of the responses was analyzed using the Flesch-Kincaid Grade Level. RESULTS: In response to the ten questions, the average DISCERN score was 44 (range 38-51). Seven responses were classified as fair and three were poor. The JAMA Benchmark criteria score was 0 for all responses. Furthermore, the average Flesch-Kincaid Grade Level was 14.35, which correlates to a college graduate reading level. CONCLUSION: Overall, ChatGPT was able to provide fair responses to common patient questions. However, the responses were all written at a college graduate reading level and lacked reliable citations. The readability greatly limits its utility. Thus, adequate patient education should be done by orthopedic surgeons. This study underscores the need for patient education resources that are reliable, accessible, and comprehensible. LEVEL OF EVIDENCE: IV.

[Application of tuberosity suture combined with autogenous bone grafting in reverse total shoulder arthroplasty for elderly patients with proximal humeral fractures].

Objective: To analyze the effectiveness of tuberosity suture combined with autogenous bone grafting in reverse total shoulder arthroplasty for elderly patients with proximal humerus fracture. Methods: A clinical data of 28 patients with fresh proximal humerus fractures, who met the selection criteria and admitted between June 2014 and April 2022, was retrospectively analyzed. There were 7 males and 21 females. Age ranged from 65 to 81 years, with an average of 73.8 years. The causes of injury were 21 cases of fall, 6 cases of traffic accident, and 1 case of falling from height. The time from injury to operation ranged from 5 to 20 days with an average of 9.2 days. There were 8 cases of Neer three-part fracture and 20 cases of four-part fracture. The reverse total shoulder arthroplasty was performed, and the greater and lesser tuberosities were sutered and reconstructed with autogenous bone grafting. After operation, the Constant score, American Society for Shoulder Surgery (ASES) score, and visual analogue scale (VAS) score were used to evaluate shoulder function and pain; and the active range of motion of the shoulder joint was recorded, including flexion, external rotation, and internal rotation. X-ray films were taken to observe the position of prosthesis. According to the evaluation criteria proposed by Boileau, the healing of greater tuberosity was evaluated, and the effectiveness was compared between the patients with healed and non-healed (displacement and absorption) greater tuberosity. Results: All incisions healed by first intention after operation. All patients were followed up 24-106 months, with an average of 60.9 months. At last follow-up, the VAS score of shoulder joint ranged from 0 to 6 (mean, 1.1). The Constant score ranged from 45 to 100 (mean, 80.1). The ASES score ranged from 57 to 100 (mean, 84.7). The active range of motions of shoulder joint were 60°-160° (mean, 118°) in flexion, 0°-50° (mean, 30°) in external rotation, and corresponding to reaching the S 5-T 8 vertebral body level in internal rotation. During follow-up, no shoulder joint re-dislocation or severe shoulder instability occurred, and no revision surgery was performed. X-ray film reexamination showed that there was no loosening of the prosthesis. According to the evaluation criteria proposed by Boileau, the greater tuberosity fused in 22 cases (78.6%), displaced in 3 cases (10.7%), and absorbed in 3 cases (10.7%). The shoulder joint function and pain related evaluation indicators in the healed group were significantly better than those in the non-healed group ( P<0.05). Conclusion: Tuberosity suture combined with autogenous bone grafting is a relatively simple procedure that provides a reliable fixation for the anatomic recovery of greater and lesser tuberosities and is beneficial for the recovery of shoulder function in elderly patients with proximal humeral fractures.

Finite element analysis part 1 of 2: Influence of short stem implant polyethylene configuration on glenohumeral joint biomechanics.

Purpose: Stress shielding in short-stem arthroplasty can cause critical metaphyseal bone loss. If the size and shape of the humeral shaft are important factors, it is unknown whether the shape of the polyethylene component in reverse shoulder arthroplasty (RSA) affects bone stress around or within the stem. We explored the impact of polyethylene shape on humeral and scapular stress distribution using a finite element model. Methods: We developed a shoulder-specific finite element model. A defined set of muscle forces was applied to simulate movements. An intact rotator cuff state and a superior deficient rotator cuff state were modelled. We used the FX V135 short stem in three conditions: total shoulder arthroplasty (TSA), and RSA with symmetrical and asymmetrical polyethylene (145°/135°). We measured biomechanical markers related to bone stress for different implant sizes. Joint kinematics and the mechanical behaviour of the implant were compared. Results: Rupture of the supraspinatus muscle produced a functionally limited shoulder. The placement of an anatomic TSA with an intact rotator cuff restored function similar to that of a healthy shoulder. RSA in the rotator cuff-deficient shoulder restored function regardless of stem size and polyethylene shape. While stem size had an impact on the stress distribution in the bone and implant, it did not show significant potential for increasing or decreasing overall stress. For the same stem, stress distribution at the humerus is different between TSA and RSA. Polyethylene shape did not alter the transmission of stress to the bone in RSA. Asymmetric polyethylene produced a greater abduction range of motion. Conclusions: In terms of bone stress distribution, smaller stems seemed more appropriate for TSA, while larger stems may be more appropriate for RSA. Polyethylene shape resulted in different ranges of motion but did not influence bone stress. Level of Evidence: Diagnostic Tests or Criteria; Level IV.