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Introduction. Bilateral posterior dislocation of the shoulder is a rare injury, accounted for about 2–5% of all shoulder dislocations. Main courses are electrical shock, epilepsy or extreme trauma with uncontrolled muscle forces. We report about a case of bilateral posterior shoulder dislocation without additional fractures but with a concomitant acromioclavicular joint dislocation. Case presentation. A 46-year-old Caucasian motorcyclist presented to our facility after a fall on slippery ground. He claimed pain in both shoulders with limited range of motion. The initial X-rays were inconclusive, clinical examination showed typical findings of a Rockwood injury with an additional limited external rotation so that a posterior shoulder dislocation was suspected. The CT scan confirmed the clinical suspicion. A closed reduction was performed followed by immobilization in a shoulder abduction pillow for 4 weeks and continuous physiotherapy. Upon follow up normal function with full range of motion was observed. Conclusion. A bilateral posterior shoulder dislocation can be caused by trauma and results in a limited range of motion with often additional injuries. Due to the unusually presentation the risk of missing the injury is increased. Therefore it is most important to consider this rare diagnosis and in case of clinical suspicion perform a careful algorithm of diagnostic. [ABSTRACT FROM AUTHOR]

Background: Autologous cancellous bone grafting still represents the gold standard for the therapy of non-healing bone defects. However, donor site morbidity and the restricted availability of autologous bone grafts have initiated scientists to look for promising alternatives to heal even large defects. The present study aimed to evaluate the biomechanical potential and failure properties of a previously developed metaphyseal critical-size defect model of the proximal tibia in minipigs for future comparisons of bone substitute materials., Methods: Fresh-frozen minipig tibiae were divided into two groups, with half undergoing the creation of critical-size defects. Specimens were subjected to biomechanical fatigue tests and load-to-failure tests. CT scans post-test verified bone damage. Statistical analysis compared the properties of defected and intact specimens., Findings: In this model, it was demonstrated that under uniaxial cyclic compression within the loading axis, the intact tibiae specimens (8708 ± 202 N) provided a significant (p = 0.014) higher compressive force to failure than the tibiae with the defect (6566 ± 1653 N)., Interpretation: Thus, the used minipig model is suitable for comparing bone substitute materials regarding their biomechanical forces and bone regeneration capacity., Competing Interests: Declaration of competing interest All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity in the younger population. The surgical management for these patients improved constantly over the last year and might not be comparable to modern treatment strategies. However, under this aspect the present investigation updates and discusses current evidence regarding the long-term outcome of the surgical management of AIS. All the clinical studies which evaluated the long-term outcomes of spinal fusion were considered. Level of evidence, clinical and radiological data, results of health-related questionnaires and surgery-associated complications during long-term follow-up, e.g., proximal and distal junctional kyphosis (PJK/DJK), and adjacent segment degeneration (ASD), are presented. Data concerning the following patient-reported outcomes measures were collected: Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) Outcome Questionnaire, visual analogue scale (VAS), and short form-12 and 36 (SF-12/SF-36). Overall, data from 1115 patients were included. Of them, 324 underwent anterior and 791 posterior spinal fusion. One study focuses on a combined anterior/posterior fusions. The mean follow-up was 22.6 years (posterior fusion: 24.6 years, anterior fusion: 18.31 years). Seven studies focus on the thoracic segments, while 12 focus on the lumbar spine. Data on imaging was reported in 13 studies and those on PROMs in 15 investigations. In conclusion, there is low quality and paucity of long-term data on AIS. However, the long-term results of the implicated studies on AIS patients in this review appear to be satisfactory, although there are limitations in the outcome compared to healthy comparison cohorts. Adjacent degenerations appear to be the most common mechanical complication after long-segment fusions, despite their influence on the outcome remains unclear. With regard to pregnancies, there are slightly increased cesarean section rates, which could be explained by deviations in the sagittal profile., (© 2024. The Author(s).)

Purpose: Vertebral Body Tethering (VBT), an alternative treatment for adolescent idiopathic scoliosis, shows satisfactory post-operative results. However, the biomechanical quantities and consequences after VBT surgery remain largely unknown. Therefore, the aim of this study is to analyze the spinal biomechanics during different motions using a multibody simulation approach., Methods: The tether and intervertebral compression forces were simulated in a validated spine model during different physiological movements at different pre-tensions and screw positions, while considering the anatomical muscle and ligament properties., Results: The simulations showed that an augmentation of the pre-tension and an alteration of the screw position have both significant impact on the intervertebral compression and tether forces. The forces also vary depending on the movement performed, with the highest tether forces measured during lateral bending. In the upright position, with a pre-tension of 200 N, the maximum compression force increases by up to 157% compared to the untethered maximum compression force. The screw position can lead to large differences in the distribution of forces in the spine., Conclusion: The biomechanical data provide a first impression of the forces that occur along the spine during various physiological movements and are consistent with published clinical data. Forces are not evenly distributed along the spine, with higher lumbar forces. The tether forces reach values during lateral bending that can potentially destroy the tether´s integrity and thus may explain the common post-operative complication, namely tether breakage. The results of the model can therefore have an impact on future directions for improved surgical VBT treatment., (© 2024. The Author(s).)

Background: Brace therapy's influence on adolescent idiopathic scoliosis's (AIS) natural course is inconclusive., Methods: Brace-treated AIS patients from 2016 to 2020 were examined regarding four endpoints at brace weaning: surgery need, curve progress ≥ 6° and > 45°, and curve improvement ≥ 6°. Prediction variables' influence was computed for the all-patients group and three subgroups (Subgroup 1: fulfilling the Scoliosis Research Society's [SRS] criteria, Subgroup 2: initial Cobb angle < 25°, Subgroup 3: initial Cobb angle > 40°). According to the data characteristics, parametric and non-parametric tests and binary logistic regression were performed., Results: The research included 69 patients. Overall, after brace weaning surgery was recommended for 20.3% of them, curve progression was ≥ 6° in 23.2%, the Cobb angle was beyond 45° in 11.6%, and the Cobb angle improved by ≥ 6° in 20.3%. Patients needing surgery had a significantly higher initial Cobb angle (38.8° ± 9.8° vs 27.8° ± 7.6°, p < 0.001), lower Risser stages (p = 0.010), and higher Nash and Moe degrees (p = 0.030). Patients with curve progress ≥ 6° were younger at first curve notification (12.4 ± 1.5 vs 13.7 ± 1.7 years, p = 0.011) and older at menarche (13.4 ± 1.1 vs 12.6 ± 1.2 years, p = 0.037). Furthermore, 21.6% of all Risser 3 and 4 patients had still curve progress ≥ 6°. In-brace correction was significantly higher in patients with curve improvement ≥ 6° vs < 6° (54.0% ± 31.2% vs 31.9% ± 30.7%; p = 0.019). Nine patients fulfilled the SRS criteria, 22 had initial Cobb angles < 25°, and 11 had > 40°. Real brace wear (RBW) in all groups had no significant effect on outcome. Two significant subgroup differences were found: Surgery recommendation and curve progression beyond 45° were significantly more frequent in the initial Cobb angle > 40° subgroup., Conclusions: Brace effectiveness can be assumed because curve improvement was achieved in nearly one-fifth with sufficient in-brace correction. However, no significant influence of RBW on the outcome endpoints was demonstrated. To clarify conflicting results, big data management, including untreated patients, must be employed to further research AIS's multifactorial influenced aetiology and course. Meanwhile, it is worth starting bracing in AIS in practice also beyond the SRS's criteria., (© 2024. The Author(s).)

Human skeletal muscle contains different types of tissues with skeletal muscle fibers (SMFs) and intermuscular adipose tissues (IMATs) as the main components. We maintained human skeletal muscle tissues from 12 study participants under native conditions in vitro for 11 days to investigate the dynamics of macrophages that reside in adjacent IMATs and SMFs simultaneously. The samples were subjected to immunohistochemical analysis for macrophage phenotyping and mitochondrial mass assessment before and after maintenance in vitro. Multiplex protein analysis was used to determine cytokine/chemokine expression in tissue extracts. The results revealed significant correlations between donor age or body mass index (BMI) and distinct phenotypes of resident macrophages in SMFs and IMATs. The dynamics of SMF- and IMAT-resident macrophages differed significantly in vitro and exhibited inverse correlations with chemokine/cytokine expression levels and mitochondrial activity. Moreover, the responses of macrophages to saturated and unsaturated fatty acids (FAs) differed substantially between SMFs and IMATs. These findings showed the functional diversity of phenotypically identical macrophages in adjacent niches. Thus, the currently available macrophage markers cannot capture the functional diversity of human tissue-resident macrophages. The model used in the present study may help elucidate how macrophages affect muscle homeostasis and disease in humans.

Purpose: This study evaluates whether the fracture level alters the outcomes of minimally invasive hybrid stabilization (MIHS) with double-threaded, uncemented polyaxial screws for unstable osteoporotic vertebral fractures., Methods: This prospective cohort study included 73 patients (71.23% females, mean age: 79.9 ± 8.8 years) with unstable OF 3-4 fractures treated by MIHS between Nov 2015-Jan 2018. Patient characteristics, operative data, clinical outcomes, complications, radiological outcomes, and midterm (24-month) follow-up regarding functionality, pain, and quality of life were analyzed., Results: Patients had thoracolumbar (71.23%), thoracic (10.97%), and lumbar (17.8%) fractures. Operative time was < 120 min in 73.97% of patients, with blood loss < 500 ml in 97.25% of cases. No in-hospital mortality was recorded. Spine-associated complications occurred in 15.07% of patients, while 36.98% of patients had urinary tract infections (n = 12), pneumonia (n = 5), and electrolyte disturbances (n = 9). The mean length of hospital stay was 13.38 ± 7.20 days. Clinically-relevant screw loosening occurred in 1.7% of screws, and secondary adjacent fractures were diagnosed in 5.48% of patients. The alpha-angle improved significantly postoperatively (mean change: 5.4°) and remained stable for 24 months. The beta-angle improved significantly from 16.3° ± 7.5 to 10.8° ± 5.6 postoperatively but increased slightly to 14.1° ± 6.2 at midterm follow-up. Although no differences were seen regarding baseline data, clinical outcomes, and complications, fracture level significantly altered the COMI score at 24 months with no effect on pain score or quality-of-life., Conclusion: MIHS using polyaxial screws is a safe treatment for single-level osteoporotic spinal fractures. Fracture level did not alter radiological reduction loss; however, it significantly altered patients' function at 24 months., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests. Ethical approval: The study protocol was approved by the regional Ethics Committee of the study center (file number: 2016448). Consent to participate: An informed consent was retrieved from all eligible individuals prior to participation in this research. Consent for publication: Not applicable., (© 2024. The Author(s).)

Purpose: Although trochanteric fractures (TF) are a frequent event in the geriatric population, studies reporting on complication rates associated with surgical treatment are sparse. Thus, this study investigated the relevance of fracture-, implant-, and surgery-associated complications in TF. Furthermore, the role of possible risk factors for the before mentioned complications was investigated., Methods: A consecutive series of patients with TF treated by intramedullary nailing with a sliding screw device was evaluated. Data were sampled retrospectively from the hospital patient information system and anonymized at the source. Demographic data and information regarding fracture pattern, the treatment performed, hospital stay, and evaluation of operative and follow-up radiographs were analyzed. Intraoperative problems (i.e., technical problems with the implant, intraoperative fracture) and postoperative complications were investigated., Results: Postoperative surgical complications were noted in 11.7%. The most frequent surgical problem was a difficult fracture reduction (13%) and intraoperative fracture dislocation (3.6%). The most frequent postoperative complication was intra-hospital mortality (3.6%), delayed/non-union (2.7%), and a cut-out of the lag screw in the femoral head (2.3%). Implant failure (1,4%) was significantly associated with morbid obesity while cut-out (2,3%) correlated with a higher tip-apex distance (TAD). A complex fracture type and a suboptimal screw position significantly increased the cut-out rate to 5% (p = 0.018)., Conclusion: Complications after TF treatment occur frequently. While patient-associated variables such as morbid obesity cannot be influenced by the surgeon, correct fracture reduction and implant positioning remain to be of highest importance., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Phenotypically heterogeneous populations of tissue-resident macrophages and stem cells play important roles in the regeneration of the skeletal muscle tissue. Previous studies using animal and cell culture models implied a beneficial effect of fatty acid (FA) species on tissue regeneration. Here, we applied a human experimental model using excised muscle tissues from reconstructive surgeries to study the effects of FAs on resident macrophages and stem cells in the natural environment of human skeletal muscle tissue. Muscle tissue samples from 20 donors were included in this study. The expression of 34 cytokines/chemokines was determined, using multiplex protein analysis. The phenotypes of macrophages and stem cells were determined immunohistochemically. The numbers of CD80 + macrophages correlated with the expression levels of IL-1α, IL-1RA, IL-8, IL-17A, and MCP-1, while the PAX7 + and MyoD + stem cell counts were positively correlated with the expression level of CXCL12α, a recognized chemoattractant for muscle stem cells. Treatment of additional tissue sections with FAs revealed that CD80 + or MARCO + macrophages- and PAX7 + or MyoD + stem cells were simultaneously increased by unsaturated long-chain FAs. Taken together, this is the first experimental demonstration of a coordinated activation of macrophages and stem cells in human skeletal muscle tissue.

Background: The surgical treatment of inferior patellar pole fractures can be a challenge, especially in geriatric patients, who are particularly frequently affected by osteoporosis. The objective of this biomechanical study was to compare the performance of suture anchor and transosseous suture fixation in fractures of the inferior patellar pole in context of bone mineral density., Methods: Twelve fresh-frozen human cadaveric knees received a transverse osteotomy, simulating an AO/OTA 34C1.3 inferior pole fracture of the patella. These fractures were fixated with either suture anchors (SA; Corkscrew ® FT 4.5 mm) or transosseous suture (TS; #2 FiberWire ® ). Cyclic loading tests were performed by pulling the quadriceps tendon against gravity from 90° flexion to almost full extension (5°) for 1000 cycles. Motion and fracture gap displacement were tracked until failure occurred. Subsequently, loading to failure tests followed. Differences between groups were compared using unpaired t-tests, and correlations were calculated with Pearson's correlation coefficient., Results: The suture anchor group showed significantly fewer cycles to failure than the transosseous suture group (SA: 539.0 ± 465.6 cycles, TS: 1000 ± 0 cycles, P = 0.04). Bone mineral density correlated positively with cycles to failure in the suture anchor group (Pearson's r = 0.60, P = 0.02). No differences in fracture gap displacement could be proven after 100 cycles (SA: 4.1 ± 2.6 mm, TS: 6.5 ± 2.6 mm, P = 0.19); 500 cycles (SA: 6.4 ± 6.1 mm, TS: 9.6 ± 3.8 mm, P = 0.39); and 1000 cycles (SA: 4.0 ± 0.4 mm, TS: 11.0 ± 4.5 mm, P = 0.08). Furthermore, the mean destructive load to failure in the suture anchor group was also significantly lower than in the transosseous suture group (SA: 422.4 ± 212.2 N, TS: 825.7 ± 189.3 N, P = 0.04)., Conclusions: Suture anchors may be a viable alternative to transosseous suture in younger patients for clinical advantages, but in osteoporotic bone, the more stable osteosynthesis with transosseous suture continues to prove superior. Therefore, trauma surgeons might consider the use of transosseous suture in elderly patients, especially in those presenting with low bone mineral density values., (© 2022. The Author(s).)

Introduction: Potential advantages of the Extreme Lateral Interbody Fusion (XLIF) approach are smaller incisions, preserving anterior and posterior longitudinal ligaments, lower blood loss, shorter operative time, avoiding vascular and visceral complications, and shorter length of stay. We hypothesize that not every patient can be safely treated at the L4/5 level using the XLIF approach. The objective of this study was to radiographically (CT-scan) evaluate the accessibility of the L4/5 level using a lateral approach, considering defined safe working zones and taking into account the anatomy of the superior iliac crest., Methods: Hundred CT examinations of 34 female and 66 male patients were retrospectively evaluated. Disc height, lower vertebral endplate (sagittal and transversal), and psoas muscle diameter were quantified. Accessibility to intervertebral space L4/5 was investigated by simulating instrumentation in the transverse and sagittal planes using defined safe zones., Results: The endplate L5 in the frontal plane considering defined safe zones in the sagittal and transverse plane (Zone IV) could be reached in 85 patients from the right and in 83 from the left side. Through psoas split, the safe zone could be reached through psoas zone II in 82 patients from the right and 91 patients from the left side. Access through psoas zone III could be performed in 28 patients from the right and 32 patients from the left side. Safe access and sufficient instrumentation of L4/5 through an extreme lateral approach could be performed in 76 patients of patients from the right and 70 patients from the left side., Conclusion: XLIF is not possible and safe in every patient at the L4/5 level. The angle of access for instrumentation, access of the intervertebral disc space, and accessibility of the safe zone should be taken into account. Preoperative imaging planning is important to identify patients who are not suitable for this procedure., (© 2022. The Author(s).)

Findings from studies of muscle regeneration can significantly contribute to the treatment of age-related loss of skeletal muscle mass, which may predispose older adults to severe morbidities. We established a human experimental model using excised skeletal muscle tissues from reconstructive surgeries in eight older adults. Muscle samples from each participant were preserved immediately or maintained in agarose medium for the following 5, 9, or 11 days. Immunofluorescence analyses of the structural proteins, actin and desmin, confirmed the integrity of muscle fibers over 11 days of maintenance. Similarly, the numbers of CD80-positive M1 and CD163-positive M2 macrophages were stable over 11 days in vitro. However, the numbers of PAX7-positive satellite cells and MYOD-positive myoblasts changed in opposite ways, suggesting that satellite cells partially differentiated in vitro. Further experiments revealed that stimulation with unsaturated fatty acid C18[2]c (linoleic acid) increased resident M1 macrophages and satellite cells specifically. Thus, the use of human skeletal muscle tissue in vitro provides a direct experimental approach to study the regulation of muscle tissue regeneration by macrophages and stem cells and their responses to therapeutic compounds.

Purpose: To determine whether internal fixation (IF) or hip arthroplasty (HA) is associated with superior outcomes in geriatric nondisplaced femoral neck fracture (FNF) patients., Methods: Data from the Registry for Geriatric Trauma of the German Trauma Society (ATR-DGU) were analyzed (IF Group 449 and HA Group 1278 patients). In-hospital care and a 120-day postoperative follow-up were conducted. Primary outcomes, including mobility, residential status, reoperation rate, and a generic health status measure (EQ-5D score), and the secondary outcome of mortality were compared between groups. Multivariable analyses were performed to assess independent treatment group associations (odds ratios, ORs) with the primary and secondary end points., Results: Patients in the HA group were older (83 vs. 81 years, p < 0.001) and scored higher on the Identification of Seniors at Risk screening (3 vs. 2, p < 0.001). We observed no differences in residential status, reoperation rate, EQ-5D score, or mortality between groups. After adjusting for key covariates, including prefracture ambulatory capacity, the mobility of patients in the HA group was more frequently impaired at the 120-day follow-up (OR 2.28, 95% confidence interval = 1.11-4.74)., Conclusion: Treatment with HA compared to treatment with IF led to a more than twofold increase in the adjusted odds of impaired ambulation at the short-term follow-up, while no significant associations with residential status, reoperation rate, EQ-5D index score, or mortality were observed. Thus, IF for geriatric nondisplaced FNFs was associated with superior mobility 120 days after surgery. However, before definitive treatment recommendations can be made, prospective, randomized, long-term studies must be performed to confirm our findings., (© 2021. The Author(s).)

Background: Proximal femur fractures (PFFs) occur frequently among geriatric patients due to diverse risk factors, such as a lower bone mineral density and the increased risk of falls., Methods: In this review, we focus on recent literature of patient-specific risk factors and their impact on common complications and outcome parameters in patients with PFF., Results: Patient- and treatment related factors have a significant impact on outcome and are associated with an increased risk of mortality, impairments in functional rehabilitation and complicative courses., Conclusion: Geriatric patients at high risk for complications are nursing home inhabitants suffering from severe osteoporosis, dementia and sarcopenia. The early and ongoing assessment for these individual risk factors is crucial. Strategies including interdisciplinary approaches, addressing comorbidities and facilitating an optimal risk factor evaluation result in a beneficial outcome. The ongoing ambulant assessment and therapy of complicating factors (e.g., malnutrition, sarcopenia, frailty or osteoporosis) have to be improved., (© 2022. The Author(s).)

Purpose: Atlas (C1) fractures are commonly rated according to the Gehweiler classification, but literature on its reliability is scarce. In addition, evaluation of fracture stability and choosing the most appropriate treatment regime for C1-injuries are challenging. This study aimed to investigate the interobserver reliability of the Gehweiler classification and to identify whether evaluation of fracture stability as well as the treatment of C1-fractures are consistent among spine surgeons., Methods: Computed tomography images of 34 C1-fractures and case-specific information were presented to six experienced spine surgeons. C1-fractures were graded according to the Gehweiler classification, and the suggested treatment regime was recorded in a questionnaire. For data analyses, SPSS was used, and interobserver reliability was calculated using Fleiss' kappa (κ) statistics., Results: We observed a moderate reliability for the Gehweiler classification (κ = 0.50), the evaluation of fracture stability (κ = 0.50), and whether a surgical or non-surgical therapy was indicated (κ = 0.53). Type 1, 2, 3a, and 5 fractures were rated stable and treated non-surgically. Type 3b fractures were rated unstable in 86.7% of cases and treated by surgery in 90% of cases. Atlas osteosynthesis was most frequently recommended (65.4%). Overall, 25.8% of type 4 fractures were rated unstable, and surgery was favoured in 25.8%., Conclusion: We found a moderate reliability for the Gehweiler classification and for the evaluation of fracture stability. In particular, diverging treatment strategies for type 3b fractures emphasise the necessity of further clinical and biomechanical investigations to determine the optimal treatment of unstable C1-fractures., (© 2020. The Author(s).)