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Abstract Background Reverse total shoulder arthroplasty (RTSA) is commonly performed to reduce pain and restore shoulder function in patients with severe shoulder conditions. While most patients experience significant pain relief and functional improvement following surgery, a subset of patients continue to report persistent pain even two years postoperatively. The aim of this study was to identify both modifiable and non-modifiable preoperative factors that contribute to the risk of persistent postsurgical pain after RTSA. By understanding these factors, clinicians can better anticipate which patients are at higher risk and develop tailored preoperative and postoperative pain management strategies to improve overall outcomes. Methods In this retrospective cohort study, 703 patients with complete data undergoing primary RTSA performed between 2011 and 2022 were analyzed. Persistent postsurgical pain was defined as a pain score ≥ 3 on a numeric rating scale. Multivariable regression models were used to identify patient-related and disease-related predictors of persistent postsurgical pain. Results The cohort comprised 445 women (63%) and 258 men (37%) with a mean age of 74 ± 8 years at the time of surgery. Persistent postsurgical pain was reported by 18% of patients. Preoperative pain scores averaged 6.0 ± 2.5 on the NRS scale, which decreased to 1.2 ± 1.8 postoperatively. Key predictors included higher preoperative pain levels (β = 0.10, p

Background: The purpose of this study was to assess impingement-free internal rotation (IR) in a virtual reverse shoulder arthroplasty simulation using a Statistical Shape Model based on scapula size. Methods: A database of over 10,000 scapulae utilized for preoperative planning for shoulder arthroplasty was analyzed with a Statistical Shape Model to obtain 5 scapula sizes including the mean and 2 standard deviations. For each scapula model, one glenosphere size (33-42 mm) was selected as the best fit based on consensus among 3 shoulder surgeons. Virtual implantation variables included 1) lateral offset (0-12 mm in 2-mm increments), 2) inferior eccentricity (0, 2.5, 5, and 7.5 mm), and 3) posterior eccentricity (0, 2.5, and 5 mm). The neck shaft angle was fixed at 135° with an inlay design humeral prosthesis. IR at the side (IR0) and in abduction (IRABD) were then simulated. Results: Maximum impingement-free IR0 was reached with increasing inferior offset in combination with increasing lateralization. Lateralization was the most important variable in increasing impingement-free IRABD. Maximum IRABD was reached at 4-6 mm of lateralization with smaller scapula (−2 to 0 standard deviation). Increasing lateralization up to 12 mm continues to increase IRABD for larger-sized scapula (+1 to +2 standard deviation). Optimal inferior offset and lateralization to maximize IR did have a small loss of external rotation in neutral abduction. There was no loss of external rotation in 60° of abduction. Conclusion: In a virtual model, the glenosphere position required to maximize IR varied by scapula size. For smaller scapulae, maximum IR0 was reached with a combination of 2.5-mm inferior offset and 0- 4 mm of lateralization. For larger scapulae, maximum IR0 was reached with a combination of 2.5 mm of inferior offset and 4 mm of lateralization. The amount of lateralization required to maximize IRABD also varies by scapula size. Maximum IRABD was reached in smaller scapula with 4-6 mm of lateralization and at least 12 mm of lateralization in larger scapula. These findings may be applied in the clinical decision-making process knowing that impingement-free IR and IRABD can be maximized with combinations of inferior offset and lateralization based on scapula size with minimal effect on external rotation and external rotation in 60° of abduction.

Aims: The liner design is a key determinant of the constraint of a reverse total shoulder arthroplasty (rTSA). The aim of this study was to compare the degree of constraint of rTSA liners between different implant systems. Methods: An implant company’s independent 3D shoulder arthroplasty planning software (mediCAD 3D shoulder v. 7.0, module v. 2.1.84.173.43) was used to determine the jump height of standard and constrained liners of different sizes (radius of curvature) of all available companies. The obtained parameters were used to calculate the stability ratio (degree of constraint) and angle of coverage (degree of glenosphere coverage by liner) of the different systems. Measurements were independently performed by two raters, and intraclass correlation coefficients were calculated to perform a reliability analysis. Additionally, measurements were compared with parameters provided by the companies themselves, when available, to ensure validity of the software-derived measurements. Results: There were variations in jump height between rTSA systems at a given size, resulting in large differences in stability ratio between systems. Standard liners exhibited a stability ratio range from 126% to 214% (mean 158% (SD 23%)) and constrained liners a range from 151% to 479% (mean 245% (SD 76%)). The angle of coverage showed a range from 103° to 130° (mean 115° (SD 7°)) for standard and a range from 113° to 156° (mean 133° (SD 11°)) for constrained liners. Four arthroplasty systems kept the stability ratio of standard liners constant (within 5%) across different sizes, while one system showed slight inconsistencies (within 10%), and ten arthroplasty systems showed large inconsistencies (range 11% to 28%). The stability ratio of constrained liners was consistent across different sizes in two arthroplasty systems and inconsistent in seven systems (range 18% to 106%). Conclusion: Large differences in jump height and resulting degree of constraint of rTSA liners were observed between different implant systems, and in many cases even within the same implant systems. While the immediate clinical effect remains unclear, in theory the degree of constraint of the liner plays an important role for the dislocation and notching risk of a rTSA system. Cite this article: Bone Jt Open 2024;5(10):818–824.

Abstract Background Insufficient tuberosity healing is the most common reason for poor outcome after treatment of proximal humerus fractures (PHFs) using hemiarthroplasty (HA). In these cases, revision to reverse total shoulder arthroplasty (RTSA) can improve function and reduce pain in the short term, however, long-term results remain scarce. Aim of this study was to evaluate the clinical and radiological mid- to long-term results in patients with a revision RTSA after failed HA for PHF. Methods In this retrospective study all patients that received a revision to RTSA after failed fracture HA between 2006 and 2018 were included. A total of 49 shoulders in 48 patients (38 female, 10 male; mean age 82 ± 9 years) were identified in our database. A total of 20 patients (17 female, 3 male; mean age was 79 ± 9 years) were available for follow-up examination after a mean time period of approximately eight years (3–14 years) after revision surgery. At final follow-up, patients were assessed using a subjective shoulder value (SSV), range of motion (ROM), visual analogue score (VAS), the Constant Score (CS) and the 12-Item Short Form Survey (SF-12). Results At final follow-up, mean CS was 55 ± 19 (19–91), VAS averaged 3 ± 3 (0–8) and mean SSV was 61 ± 18% (18–90%). Mean SF-12 was 44 (28–57) with a mean physical component summary (PCS) of 38 (21–56) and a mean mental component summary (MCS) of 51 (29–67). On average active forward flexion (FF) was 104° (10–170°), active abduction (ABD) was 101° (50–170°), active external rotation (ER) was 19° (10–30°) and active internal rotation (IR) of the lumbosacral transition was reached. Three patients presented with a periprosthetic humeral fracture after RTSA implantation and underwent a reoperation (15%) during follow-up period. Conclusions Revision RTSA results in promising clinical results in patients after initial failed HA after PHF. A complication and reoperation rate of 15% is tolerable in consideration of satisfactory functional and psychological outcome. Trial registration Retrospectively registered.

Aims: Current diagnostic tools are not always able to effectively identify periprosthetic joint infections (PJIs). Recent studies suggest that circulating microRNAs (miRNAs) undergo changes under pathological conditions such as infection. The aim of this study was to analyze miRNA expression in hip arthroplasty PJI patients. Methods: This was a prospective pilot study, including 24 patients divided into three groups, with eight patients each undergoing revision of their hip arthroplasty due to aseptic reasons, and low- and high-grade PJI, respectively. The number of intraoperative samples and the incidence of positive cultures were recorded for each patient. Additionally, venous blood samples and periarticular tissue samples were collected from each patient to determine miRNA expressions between the groups. MiRNA screening was performed by small RNA-sequencing using the miRNA next generation sequencing (NGS) discovery (miND) pipeline. Results: Overall, several miRNAs in plasma and tissue were identified to be progressively deregulated according to ongoing PJI. When comparing the plasma samples, patients with a high-grade infection showed significantly higher expression levels for hsa-miR-21-3p, hsa-miR-1290, and hsa-miR-4488, and lower expression levels for hsa-miR-130a-3p and hsa-miR-451a compared to the aseptic group. Furthermore, the high-grade group showed a significantly higher regulated expression level of hsa-miR-1260a and lower expression levels for hsa-miR-26a-5p, hsa-miR-26b-5p, hsa-miR-148b-5p, hsa-miR-301a-3p, hsa-miR-451a, and hsa-miR-454-3p compared to the low-grade group. No significant differences were found between the low-grade and aseptic groups. When comparing the tissue samples, the high-grade group showed significantly higher expression levels for 23 different miRNAs and lower expression levels for hsa-miR-2110 and hsa-miR-3200-3p compared to the aseptic group. No significant differences were found in miRNA expression between the high- and low-grade groups, as well as between the low-grade and aseptic groups. Conclusion: With this prospective pilot study, we were able to identify a circulating miRNA signature correlating with high-grade PJI compared to aseptic patients undergoing hip arthroplasty revision. Our data contribute to establishing miRNA signatures as potential novel diagnostic and prognostic biomarkers for PJI. Cite this article: Bone Jt Open 2024;5(6):479–488.

Posterior shoulder instability (PSI) is less common than anterior shoulder instability, accounting for 2–12% of total shoulder instability cases. However, a much higher frequency of PSI has been recently indicated, suggesting that PSI accounts for up to 24% of all young and active patients who are surgically treated for shoulder instability. This differentiation might be explained due to the frequent misinterpretation of vague symptoms, as PSI does not necessarily present as a recurrent posterior instability event, but often also as mere shoulder pain during exertion, limited range of motion, or even as yet asymptomatic concomitant finding. In order to optimize current treatment, it is crucial to identify the various clinical presentations and often unspecific symptoms of PSI, ascertain the causal instability mechanism, and accurately diagnose the subgroup of PSI. This review should guide the reader to correctly identify PSI, providing diagnostic criteria and treatment strategies.

Abstract Background The importance of several scapulothoracic muscles, including trapezius and serratus anterior, in maintaining physiological scapula kinematics has been highlighted in the past. However, the relationship between the scapula and the latissimus dorsi muscle remains unclear. Our clinical surgical observation is that the latissimus dorsi does not directly attach but rather runs superficial to the inferior angle of the scapula. Based on this observation, we hypothesise that the latissimus dorsi creates a dynamic track on which the scapula glides under the muscle belly during elevation of the arm, creating the latissimus-scapula overlap (LSO). Methods All consecutive patients who had a whole-body computed tomography scan (CT) in case of polytrauma evaluation between 2018 and 2021, with complete depiction of the scapula and latissimus dorsi muscle, were analysed. 150 shoulders in 90 patients with arms up were matched according to their age (within five years), gender, and affected side with 150 shoulders in 88 patients with arms down. Patients with pathologies of the upper extremities or thorax that potentially could alter LSO measurements were excluded. LSO was calculated as a ratio of the measured area of the latissimus dorsi projection on the scapula and the total scapula area. Results The mean age of the 178 patients (48 females; 13 males) was 60 years. The arms-up group showed a significantly higher LSO than the arms-down group (19.9 ± 6.3% vs. 2.7 ± 2.2%; p

Abstract Background The two major reverse shoulder arthroplasty (RSA) designs are the Grammont design and the lateralized design. Even if the lateralized design is biomechanically favored, the classic Grammont prosthesis continues to be used. Functional and subjective patient scores as well as implant survival described in the literature so far are comparable to the lateralized design. A pure comparison of how the RSA design influences outcome in patients has not yet been determined. The aim of this study was a comparison focused on patients with cuff tear arthropathy (CTA). Methods We analyzed registry data from 696 CTA patients prospectively collected between 2012 and 2020 in two specialized orthopedic centers up to 2 years post-RSA with the same follow-up time points (6,12 24 months). Complete teres minor tears were excluded. Three groups were defined: group 1 (inlay, 155° humeral inclination, 36 + 2 mm eccentric glenosphere (n = 50)), group 2 (inlay, 135° humeral inclination, 36 + 4 mm lateralized glenosphere (n = 141)) and group 3 (onlay, 145° humeral inclination, + 3 mm lateralized base plate, 36 + 2 mm eccentric glenosphere (n = 35)) We compared group differences in clinical outcomes (e.g., active and passive range of motion (ROM), abduction strength, Constant-Murley score (CS)), radiographic evaluations of prosthetic position, scapular anatomy and complications using mixed models adjusted for age and sex. Results The final analysis included 226 patients. The overall adjusted p-value of the CS for all time-points showed no significant difference (p = 0.466). Flexion of group 3 (mean, 155° (SD 13)) was higher than flexion of group 1 (mean, 142° (SD 18) and 2 (mean, 132° (SD 18) (p

Background: Improvements in pain control after shoulder arthroplasty with a reduction in narcotic use continues to be an important postoperative goal. With the increased utilization of stemless anatomic total shoulder arthroplasty (aTSA), it is relevant to compare between stemmed and stemless arthroplasty to assess if there is any association between this implant design change and early postoperative pain. Methods: Patients from a multicenter, prospectively-maintained database who had undergone a stemless aTSA with a minimum of two year clinical follow-up were retrospectively identified. Patients who underwent aTSA with a short stem were identified in the same registry, and matched to the stemless aTSA patients by age, sex and preoperative pain score. The primary study outcome was the Visual Analog Scale pain score. Secondary pain outcomes were the American Shoulder and Elbow Surgeons shoulder pain subscore, Western Ontario Osteoarthritis of the Shoulder physical symptoms subscore, and the Single Assessment Numeric Evaluation score. Finally, the percentage of patients who could sleep on the affected shoulder was assessed for each group. These pain-related clinical outcomes were assessed and compared preoperatively, and postoperatively at 9 weeks, 26 weeks, one year and two years. For all statistical comparisons, P > .05 was considered significant. Results: 124 patients were included in the study; 62 in each group. At 9 weeks after surgery, statistically significantly improved pain control was reported by patients undergoing stemless aTSA, as assessed by the Visual Analog Scale (stemless: 1.5, stemmed: 2.5, P = .001), American Shoulder and Elbow Surgeons pain subscore (stemless: 42.4, stemmed: 37.3, P

Background: Increased coracoclavicular distance due to acute acromioclavicular joint (ACJ) instability is often described as a pseudoelevation of the clavicle due to inferior hanging of the scapula, while the distal clavicle remains in its position. The aim of this study was to analyze whether the elevation of the distal clavicle, depression of the scapula, or both are associated with vertical instability and to evaluate the impact of weighted stress radiographs on the clavicle and scapular position in acute ACJ instabilities. Methods: The cohort consisted of 505 patients (f = 52, m = 453; mean age 46 years) which presented to our emergency department or outpatient clinic and treated in our institution from 2006 to 2019 displaying an acute ACJ injury. The panorama views that displayed at least two vertebraes with their spinous processes were retrospectively evaluated. Two raters assessed the panorama views twice regarding the clavicular and coracoidal angle of both sides in relation to the cervicothoracal spine and the difference in height of both clavicles and coracoids. Results: In our cohort, five types of displacement were distinguished: type A, only clavicle is elevated (N = 46); B, only scapula depressed (N = 36); C, the clavicle elevated and the scapula depressed (N = 67); D, both depressed (N = 133); and E, both elevated (N = 223). 123 patients had non-weighted radiographs and 353 patients stress views with 10 kg of axial load, whereas 29 patients had both radiological modalities. Among these 29 patients, a significant increase in coracoclavicular distance difference, clavicle, and scapula height (P

Abstract Background Scapulothoracic orientation, especially scapular internal rotation (SIR) may influence range of motion in reverse total shoulder arthroplasty (RTSA) and is subjected to body posture. Clinical measurements of SIR rely on apical bony landmarks, which depend on changes in scapulothoracic orientation, while radiographic measurements are often limited by the restricted field of view (FOV) in CT scans. Therefore, the goal of this study was (1) to determine whether the use of CT scans with a limited FOV to measure SIR is reliable and (2) if a clinical measurement could be a valuable alternative. Methods This anatomical study analyzed the whole-body CT scans of 100 shoulders in 50 patients (32 male and 18 female) with a mean age of 61.2 ± 20.1 years (range 18; 91). (1) CT scans were rendered into 3D models and SIR was determined as previously described. Results were compared to measurements taken in 2D CT scans with a limited FOV. (2) Three apical bony landmarks were defined: (the angulus acromii (AA), the midpoint between the AA and the coracoid process tip (C) and the acromioclavicular (AC) joint. The scapular axis was determined connecting the trigonum scapulae with these landmarks and referenced to the glenoid center. The measurements were repeated with 0°, 10°, 20°, 30° and 40° anterior scapular tilt. Results Mean SIR was 44.8° ± 5.9° and 45.6° ± 6.6° in the 3D and 2D model, respectively (p

So far, tendon regeneration has mainly been analyzed independent from its adjacent tissues. However, the subacromial bursa in particular appears to influence the local inflammatory milieu in the shoulder. The resolution of local inflammation in the shoulder tissues is essential for tendon regeneration, and specialized pro-resolving mediators (SPMs) play a key role in regulating the resolution of inflammation. Here, we aimed to understand the influence of the bursa on disease-associated processes in neighboring tendon healing. Bursa tissue and bursa-derived cells from patients with intact, moderate and severe rotator cuff disease were investigated for the presence of pro-resolving and inflammatory mediators, as well as their effect on tenocytes and sensitivity to mechanical loading by altering SPM signaling mediators in bursa cells. SPM signal mediators were present in the bursae and altered depending on the severity of rotator cuff disease. SPMs were particularly released from the bursal tissue of patients with rotator cuff disease, and the addition of bursa-released factors to IL-1β-challenged tenocytes improved tenocyte characteristics. In addition, mechanical loading modulated pro-resolving processes in bursa cells. In particular, pathological high loading (8% strain) increased the expression and secretion of SPM signaling mediators. Overall, this study confirms the importance of bursae in regulating inflammatory processes in adjacent rotator cuff tendons.

Background: Metallic humeral and glenoid lateralized implants have been developed to prevent common problems that can emerge using Grammont’s concept (ie, medialization of center of rotation, decreased humeral offset, scapular notching) in reverse shoulder arthroplasty. The purpose of this study was to evaluate the clinical and radiological results of metallic humeral and glenoid lateralized implants for cuff tear arthropathy (CTA) and primary osteoarthritis (OA). Methods: In this prospective study, patients with CTA or OA who underwent reverse shoulder arthroplasty using augmented base plates for glenoid lateralization and a “curved stem” design for the humeral side were included. The Constant-Murley score and Subjective Shoulder Value were documented at 1- and 2-year follow-ups. Radiographs were reviewed for scapular notching, instability, loosening, osteolysis, ossification, bone resorption, or fractures. Lateralization and distalization shoulder angles were evaluated at the final follow-up. Results: There were 23 patients with CTA and 19 patients with OA (27 women; mean age, 76 years; range, 59-85) available for examination at 2 years. Both groups increased significantly in all outcome measures compared with baseline (P

Abstract Background The role of the subacromial bursa in the development or healing of shoulder pathologies is unclear. Due to this limited knowledge, we aimed to understand specific reactions of the subacromial bursa according to rotator cuff (RC) pathologies compared to non-tendon defects of the shoulder. We hypothesized that the tissue composition and inflammatory status of the bursa are likely to vary between shoulder pathologies depending on the presence and the extent of RC lesion. Method Bursa samples from patients with either 1) shoulder instability with intact RC (healthy bursa, control), 2) osteochondral pathology with intact RC, 3) partial supraspinatus (SSP) tendon tear, or 4) full-thickness SSP tear were investigated histologically and on gene expression level. Result Bursae from SSP tears differed from non-tendon pathologies by exhibiting increased chondral metaplasia and TGFβ1 expression. MMP1 was not expressed in healthy bursa controls, but strongly increased with full-thickness SSP tears. Additionally, the expression of the inflammatory mediators IL1β, IL6, and COX2 increased with the extent of SSP tear as shown by correlation analysis. In contrast, increased angiogenesis and nerve fibers as well as significantly upregulated IL6 and COX2 expression were features of bursae from patients with osteochondral pathology. Using immunohistochemistry, CD45+ leukocytes were observed in all examined groups, which were identified in particular as CD68+ monocytes/macrophages. Conclusion In summary, besides the strong increase in MMP1 expression with SSP tear, molecular changes were minor between the investigated groups. However, expression of pro-inflammatory cytokines correlated with the severity of the SSP tear. Most pronounced tissue alterations occurred for the osteochondral pathology and full-thickness SSP tear group, which demonstrates that the bursal reaction is not exclusively dependent on the occurrence of an SSP tear rather than longstanding degenerative changes. The present bursa characterization contributes to the understanding of specific tissue alterations related to RC tears or non-tendon shoulder pathologies. This pilot study provides the basis for future studies elucidating the role of the subacromial bursa in the development or healing of shoulder pathologies.

Abstract Background Irreparable massive rotator cuff tears (IMRCTs) are a well-known cause for functional limitation and difficult to treat. Although several joint-preserving as well as joint-replacing procedures were found to provide pain relief and gain of function, midterm results are scarce, particularly in pseudoparetic shoulder joints unaccompanied by severe osteoarthritis. The purpose of this study was to compare the midterm functional outcomes of arthroscopic procedures to those of reverse total shoulder arthroplasty (RTSA) in pseudoparetic shoulders with IMRCTs unaccompanied by severe osteoarthritis. Methods All patients who underwent either joint-preserving (group A) or joint-replacing (group B) procedures for IMRCT unaccompanied by severe osteoarthritis with a pseudoparetic shoulder function were retrospectively included. Clinical assessment included the Constant Score (CS), the Subjective Shoulder Value (SSV) and the Visual Analog Score (VAS) at baseline and at latest follow-up. Furthermore, the complication and revision rates were assessed. Results Overall, a total 56 patients were included of whom each 28 patients formed group A (male, 36%) and B (male, 53%) with a mean patient age at time of surgery of 70 ± 7 years and 72 ± 7 years, respectively. The mean follow-up period was 56 ± 17 months. At final follow-up, the total CS (group A: 66 ± 14 points; group B 54 ± 15 points) was significantly increased after arthroscopic treatment when compared to RTSA (p=0.011). However, no significant differences were detected with SSV (p=0.583) and VAS (p=0.536). Although complication rate (11% versus 18%) was not significantly different (p=0.705), number of revision surgeries was significantly higher in group B when compared to group A (p=0.041). Conclusions In non-arthritic pseudoparetic shoulders, both joint-preserving and joint-replacing procedures yielded good clinical midterm outcomes for the treatment of degenerative IMRCTs. Despite of comparable functional and satisfactory functional improvement, increased complication rates and surgical invasiveness outweigh the benefits of primary RTSA and therefore reserve this procedure to a second-line treatment in pseudoparetic patients without any signs of severe cuff arthropathy.

Abstract Background The aim of this study was to investigate the prevalence of positive microbiology samples after osteosynthesis of proximal humerus fractures at the time of revision surgery and evaluate clinical characteristics of patients with positive culture results. Methods All patients, who underwent revision surgery after locked platting, medullary nailing or screw osteosynthesis of proximal humeral fractures between April 2013 and July 2018 were retrospectively evaluated. Patients with acute postoperative infections, those with apparent clinical signs of infection and those with ≤1 tissue or only sonication sample obtained at the time of implant removal were excluded. Positive culture results of revision surgery and its correlation with postoperative shoulder stiffness was analyzed in patients with an interval of ≥6 months between the index osteosynthesis and revision surgery. Results Intraoperatively obtained cultures were positive in 31 patients (50%). Cutibacterium acnes was the most commonly isolated microorganism, observed in 21 patients (67.7%), followed by coagulase negative staphylococci in 12 patients (38.7%). There were significantly more stiff patients in the culture positive group compared to the culture-negative group (19/21, 91% vs. 15/26, 58%, p = 0.02). Furthermore, 11 of 12 (91.7%) patients with growth of the same microorganism in at least two samples had a stiff shoulder compared to 23 of 35 (65.7%) patients with only one positive culture or negative culture results (p = 0.14). Conclusion Infection must always be considered as a possibility in the setting of revision surgery after proximal humerus osteosynthesis, especially in patients with postoperative stiffness.

Abstract Background Functional shoulder instability (FSI) is defined as glenohumeral instability that is not caused by structural defects but rather by abnormal muscle activation patterns. Patients with FSI are able to dislocate their shoulder at will, either by motion (positional FSI) or even without moving the arm (non-positional FSI). In contrast to structural shoulder instability, little is known about the epidemiology of FSI. The aim of the following study was to further analyse this rare pathology and approximate the prevalence of FSI. Methods A self-evaluated and anonymous online survey among 5866 medical students was conducted using the students email list of two german-speaking medical universities (Study Center 1 and Study Center 2). Possibly affected siblings were used as a supplementary group (Siblings Cohort). General sociodemographic data, dislocation mechanism, potential causes, age at the tie of developing first symptoms, general hyperlaxity, previous interventions, and sporting activity were evaluated and analyzed. The total number of email recipients and responses was used to estimate the minimal and maximal prevalence of FSI. Results Five hundred thirteen questionnaires were completed by the students and subsequently analyzed. In total, there were 32 participants with FSI. The minimal prevalence of FSI was found to be 0,5% and the maximal prevalence 2,6%. In most cases (67%) a positional FSI was reported. The majority of the patients reported that first symptoms developed under the age of 16 years (69%) and without any traumatic event (72%). Most of the affected participants had no therapeutic intervention for their FSI (69%) and performed non-overhead (59%) or overhead sports (28%). Conclusion Functional shoulder instability (FSI) is more common than expected amongst young adults and seems to develop during childhood mostly without specific reason.

The mechano-response of highly loaded tissues such as bones or tendons is well investigated, but knowledge regarding the mechano-responsiveness of adjacent tissues such as the subacromial bursa is missing. For a better understanding of the physiological role of the bursa as a friction-reducing structure in the joint, the study aimed to analyze whether and how bursa-derived cells respond to physiological and pathological mechanical loading. This might help to overcome some of the controversies in the field regarding the role of the bursa in the development and healing of shoulder pathologies. Cells of six donors seeded on collagen-coated silicon dishes were stimulated over 3 days for 1 or 4 h with 1, 5, or 10% strain. Orientation of the actin cytoskeleton, YAP nuclear translocation, and activation of non-muscle myosin II (NMM-II) were evaluated for 4 h stimulations to get a deeper insight into mechano-transduction processes. To investigate the potential of bursa-derived cells to adapt their matrix formation and remodeling according to mechanical loading, outcome measures included cell viability, gene expression of extracellular matrix and remodeling markers, and protein secretions. The orientation angle of the actin cytoskeleton increased toward a more perpendicular direction with increased loading and lowest variations for the 5% loading group. With 10% tension load, cells were visibly stressed, indicated by loss in actin density and slightly reduced cell viability. A significantly increased YAP nuclear translocation occurred for the 1% loading group with a similar trend for the 5% group. NMM-II activation was weak for all stimulation conditions. On the gene expression level, only the expression of TIMP2 was down-regulated in the 1 h group compared to control. On the protein level, collagen type I and MMP2 increased with higher/longer straining, respectively, whereas TIMP1 secretion was reduced, resulting in an MMP/TIMP imbalance. In conclusion, this study documents for the first time a clear mechano-responsiveness in bursa-derived cells with activation of mechano-transduction pathways and thus hint to a physiological function of mechanical loading in bursa-derived cells. This study represents the basis for further investigations, which might lead to improved treatment options of subacromial bursa-related pathologies in the future.

Introduction In the field of arthroscopic rotator cuff repair (ARCR), reporting standards of published studies differ dramatically, notably concerning adverse events (AEs). In addition, prognostic studies are overall methodologically poor, based on small data sets and explore only limited numbers of influencing factors. We aim to develop prognostic models for individual ARCR patients, primarily for the patient-reported assessment of shoulder function (Oxford Shoulder Score (OSS)) and the occurrence of shoulder stiffness 6 months after surgery. We also aim to evaluate the use of a consensus core event set (CES) for AEs and validate a severity classification for these events, considering the patient’s perspective.Methods and analysis A cohort of 970 primary ARCR patients will be prospectively documented from several Swiss and German orthopaedic clinics up to 24 months postoperatively. Patient clinical examinations at 6 and 12 months will include shoulder range of motion and strength (Constant Score). Tendon repair integrity status will be assessed by ultrasound at 12 months. Patient-reported questionnaires at 6, 12 and 24 months will determine functional scores (subjective shoulder value, OSS), anxiety and depression scores, working status, sports activities, and quality of life (European Quality of Life 5 Dimensions 5 Level questionnaire). AEs will be documented according to a CES. Prognostic models will be developed using an internationally supported regression methodology. Multiple prognostic factors, including patient baseline demographics, psychological, socioeconomic and clinical factors, rotator cuff integrity, concomitant local findings, and (post)operative management factors, will be investigated.Ethics and dissemination This project contributes to the development of personalised risk predictions for supporting the surgical decision process in ARCR. The consensus CES may become an international reference for the reporting of complications in clinical studies and registries. Ethical approval was obtained on 1 April 2020 from the lead ethics committee (EKNZ, Basel, Switzerland; ID: 2019-02076). All participants will provide informed written consent before enrolment in the study.Trial registration number NCT04321005.Protocol version Version 2 (13 December 2019).

Irreparable supraspinatus tendon tears are challenging to treat, especially in a young and high-demanding patient population. Whereas interposition tendon grafting and partial repair are limited by the quality of the remaining rotator cuff tendons and muscles, superior capsular reconstruction and subacromial spacers do not provide the active biomechanical principle of a contracting supraspinatus. The purpose of this technical note is to introduce an arthroscopic middle trapezius transfer below the acromion to replace the former supraspinatus unit. This technique might combine the benefits of both the static concepts seen with subacromial spacers or superior capsular reconstruction and dynamic concepts such as interposition grafting and partial repairs.

Abstract Purpose The purpose of this study was to investigate the anatomical feasibility of a middle trapezius transfer below the acromion for treatment of irreparable supraspinatus tendon tears. Methods This study involved 20 human cadaveric shoulders in 10 full‐body specimens. One shoulder in each specimen was dissected and assessed for muscle and tendon extent, force vectors, and distance to the neurovascular structures. The opposite shoulder was used to evaluate the surgical feasibility of the middle trapezius transfer via limited skin incisions along with an assessment of range of motion and risk of neurovascular injury following transfer. Results The harvested acromial insertion of the middle trapezius tendon showed an average muscle length of 11.7 ± 3.0 cm, tendon length of 2.7 ± 0.9 cm, footprint length of 4.3 ± 0.7 cm and footprint width of 1.4 ± 0.5 cm. The average angle between the non‐transferred middle trapezius transfer and the supraspinatus was 33 ± 10° in the transversal plane and 34 ± 14° in the coronal plane. The mean distance from the acromion to the neurovascular bundle was 6.3 ± 1.3 cm (minimum: 4.0 cm). During surgical simulation there was sufficient excursion of the MTT without limitation of range of motion in a retracted scapular position but not in a protracted position. No injuries to the neurovascular structures were noted. Conclusion Transfer of the acromial portion of the middle trapezius for replacement of an irreparable supraspinatus seems to be feasible in terms of size, vector, excursion, mobility and safety. However, some concern regarding sufficiency of transfer excursion remains as scapula protraction can increase the pathway length of the transfer. Level of evidence Basic Science Study/Anatomical Study

Irreparable rotator cuff tears are challenging to treat. Especially in younger patients without concomitant osteoarthritic changes, joint-preserving procedures are warranted. To date, no treatment guideline exists because none of the available techniques has shown superiority over the others, and long-term survivorship data are missing. The aim of the “Strings” is to provide an arthroscopic solution to anatomically reconstruct presumably irreparable rotator cuff tears by bridging the gap with multiple string-like tendon interposition autografts.

Background:. Some unfavorable local events following shoulder arthroplasty occur without the patient experiencing symptoms and yet may be detected on diagnostic imaging, thereby serving as indicators of complications that may require revision. Our aim was to create a standardized protocol for an image-based monitoring process for assessing patients who are asymptomatic following shoulder arthroplasty. Methods:. A Delphi exercise was implemented with the participation of an international panel of experienced shoulder surgeons. On the basis of expert opinion from a core steering group, an initial list of imaging parameters for shoulder arthroplasty monitoring of asymptomatic patients was developed and reviewed by panel members. The most appropriate imaging modality was identified. Between each survey, all feedback was considered in order to revise the proposed core set with its definitions and specifications. Consensus was reached upon a two-thirds agreement. Results:. Three online surveys were administered, with 98 surgeons responding to the first and/or the second survey. The response rate for the final survey was 74%. Final parameter definitions were organized in 7 categories (implant migration, radiolucency around implant and implant loosening, signs of shoulder displacement, bone resorption and formation, wear of implant articular surfaces, fractures around the implant, and implant breakage and disassembly) and approved with 85% to 100% agreement. Seventy-eight percent of the panel members agreed on a minimum radiographic imaging schedule: standard anteroposterior and axial (alternatively, Y) views made within 6 weeks after implantation and between 3 and 6 months as well as at 12 months post-surgery. Conclusions:. Our work presents a monitoring tool developed with international consensus for the assessment of asymptomatic patients after shoulder arthroplasty and including a structured core set of radiographic parameters. Clinical application and scientific evaluation of the monitoring process are needed. Clinical Relevance:. This represents a major step toward the standardization of shoulder arthroplasty radiographic monitoring for routine quality controls and research investigations.

Abstract Background Acromial morphology has previously been defined as a risk factor for some shoulder pathologies. Yet, study results are inconclusive and not all major shoulder diseases have been sufficiently investigated. Thus, the aim of the present study was to analyze predictive value of three radiological parameters including the critical shoulder angle, acromion index, and lateral acromion angle in relationship to symptomatic patients with either cuff tear arthropathy, glenohumeral osteoarthritis, rotator cuff tear, impingement, and tendinitis calcarea. Methods A total of 1000 patients’ standardized true-anteroposterior radiographs were retrospectively assessed. Receiver-operating curve analyses and multinomial logistic regression were used to examine the association between shoulder pathologies and acromion morphology. The prediction model was derived from a development cohort and applied to a validation cohort. Prediction model’s performance was statistically evaluated. Results The majority of radiological measurements were significantly different between shoulder pathologies, but the critical shoulder angle was an overall better parameter to predict and distinguish between the different pathologies than the acromion index or lateral acromion angle. Typical critical shoulder angle-age patterns for the different shoulder pathologies could be detected. Patients diagnosed with rotator cuff tears had the highest, whereas patients with osteoarthritis had the lowest critical shoulder angle. The youngest patients were in the tendinitis calcarea and the oldest in the cuff tear arthropathy group. Conclusions The present study showed that critical shoulder angle and age, two easily assessable variables, adequately predict different shoulder pathologies in patients with shoulder complaints.

To date, specific surgical procedures are available for the treatment of anterior shoulder instability with substantial bony glenoid defects, as well as for patients without osseous lesions. However, specific treatment options are lacking for the frequently observed small to intermediate glenoid defects, which may not necessitate glenoid reconstruction surgery according to current guidelines but can still jeopardize the outcome after mere soft-tissue stabilization procedures. This article describes the so-called arthroscopic Bankart-Plus procedure for the treatment of anterior shoulder instability with small to intermediate bony glenoid defects. In addition to the conventional capsulolabral repair, an allogeneic demineralized spongy bone matrix is inserted between the glenoid neck and the labrum with the aim of compensating for the glenoid bone loss by increasing the volume of the labrum and thus its stabilizing effect.