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The first rare-earth-doped fiber lasers were operated in the early 1960s, and produced a few milliwatts at a wavelength around 1 mum. Since the beginning of the decade, an enormous increase of fiber laser output power has been reported, the realm of kilowatt power has been entered, and power levels as high as 100 kW are envisaged. Apart from the power, fiber laser systems are renowned for their inherent compactness, monolithic architecture, and a power-independent beam quality. This paper reviews the challenges, achievements, and perspectives of high-power continuous-wave (CW) laser generation and amplification in fibers. [ABSTRACT FROM PUBLISHER]

Purpose: Injuries exert a detrimental impact on the team performance in professional football. Shoulder dislocations are known for their severity and often cause substantial lay-off times. However, there is a notable gap in the general understanding regarding the frequency and convalescence of these events in professional football. Thus, the aims of this study were (1) to determine the incidence, (2) to evaluate return to competition (RTC) and redislocation events (RDEs) and (3) to identify relevant player-, match- and injury-related parameters., Methods: All shoulder dislocations within the highest three German football leagues (1.-3. Bundesliga) during the seasons 2012/2013 until 2022/2023 were identified. Player-, injury- and match-related data were obtained by performing a media analysis. Data were analysed using descriptive statistics. p Value was set at 0.05., Results: A total of 90 first-time shoulder dislocations in 89 players with a median age of 25 years (interquartile range [IQR]: 23-28) were available for analysis. The incidence was 9.1 per 1000 Bundesliga matches played and increased over time. Forty-four (49%) shoulder dislocations were treated conservatively and 46 (51%) operatively. Median RTC was 24 days (IQR: 12-43) following conservative and 103 days (IQR: 85-135) following surgical treatment (p < 0.001). Twenty-two (24%) players suffered a redislocation, of whom 13 (59%) underwent initial conservative and nine (41%) initial surgical treatment (not significant [n.s.]). RDE following conservative treatment was after a median of 4 months (IQR: 2-22) and 7 months (IQR: 3-23) following surgical treatment (n.s.)., Conclusion: The incidence of shoulder dislocation within professional football is increasing and currently amounts to 9.1 per 1000 matches played. A conservative treatment leads to a quicker RTC, while frequency and time to RDE were similar regardless of treatment. The increasing incidence of shoulder dislocations in professional football necessitates an analysis of relevant injury mechanisms and the implementation of specific preventive measures., Level of Evidence: Level III., (© 2024 The Authors. Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Background: Synovial leukocyte count analysis is an important tool in the diagnosis of PJI. However, results can be poor if metallosis is present. The issue of metallosis was established for some rotating hinge knee arthroplasty designs., Methods: This was a retrospective single-center analysis that included 108 patients who had a single-design metal-on-metal rotating hinge knee arthroplasty who underwent revision surgery and had prior synovial fluid analysis performed. The diagnostic accuracy of leukocyte count and the percentage of polymorphonuclear neutrophiles (% PMN) were investigated., Results: Patients who had a PJI had a higher median leukocyte count and % PMN compared to aseptic revisions (7,905/μL (interquartile range (IQR) 2,419 to 37,400) and 85% (IQR 70.3 to 93.8) versus 450 (IQR 167 to 1,215) and 46% (IQR 28.5 to 67.4%), P < .001). The respective areas under the curves were 0.916 (95% confidence interval 0.862 to 0.970) for leukocyte count and 0.821 (95% confidence interval 0.739 to 0.902) for % PMN. We calculated an optimal cut-off value of 1,200 leukocytes/μL (Sensitivity 94.5%/specificity 75.5%) and 63% PMN (Sensitivity 85.5%/specificity 73.6%) to define PJI. Established thresholds were less sensitive, but more specific. The "infection likely" scenario of the European Bone and Joint Infection Society (EBJIS) definition was closest to the calculated thresholds., Conclusion: Currently used thresholds for leukocyte cell count and %PMN to define PJI were less sensitive and specific in the diagnosis of PJI in metal-on-metal RHK knees. Surgeons must consider lower cut-off values when evaluating such implants for PJI., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Purpose: Immobilization, especially of the lower extremity, after orthopaedic surgery has been associated with reduced physical activity. Previous interventions from our study group showed even in young, healthy people reduced activity levels after immobilization of the shoulder. Therefore, this study investigates the change in physical activity due to shoulder immobilization after a reconstructive surgery., Methods: This prospective study includes 40 patients undergoing surgery from May 2019 to December 2020. Daily activity was measured before surgery, after discharge and three weeks postoperatively each time for six days. Activity including step counts and active time were measured by Fitbit™ inspire. Range of motion before and after surgery as well as Pain (VAS) were documented., Results: Steps became significantly less immediately postoperatively with an immobilized shoulder joint than before surgery (9728.8 vs. 6022.6, p < 0.05). At follow-up, the number of steps increased again, but still showed a significantly lower number of steps (mean 8833.2) compared to preoperative. Patients preoperatively showed mostly an "active" activity pattern, whereas postoperatively a "low active" behaviour predominated. The proportion of sedentary behaviour ("basal activity" and "limited activity") was almost three times higher postoperatively (12.5% vs. 30%)., Conclusion: General physical activity is restricted during upper limb immobilization in adults. Therefore, activity-enhancing measures should be implemented in the early phase of rehabilitation after upper extremity surgery., (© 2023. The Author(s).)

In the framework of the Laser Lightning Rod project, whose aim is to show that laser-induced filaments can guide lightning discharges over considerable distances, we study over a distance of 140 m the filaments created by a laser system with J-range pulses of 1 ps duration at 1 kHz repetition rate. We investigate the spatial evolution of the multiple filamentation regime using the fundamental beam at 1030 nm or using combination with the second and third harmonics. The measurements were made using both a collimated beam and a loosely focused beam., (© 2023. The Author(s).)

Background: Chronic periprosthetic joint infection after revision hip and knee arthroplasties can lead to subsequent massive femoral bone loss. In these cases, resection of the residual femur and placement of an antibiotic total femoral spacer can be an option to salvage the limb., Methods: This is a single-center retrospective analysis of 32 patients (median age 67 years; range 15-93; 18 women) who underwent placement of a total femur spacer for chronic periprosthetic joint infection with massive femoral bone loss between 2010 and 2019 as part of a planned two-stage exchange. The median follow-up period amounted to 46 months (range, 1-149). Implant and limb survival were analyzed using Kaplan-Meier survival estimates. Potential risk factors for failure were analyzed., Results: There were 34% (11 of 32) of patients having a spacer-associated complication, and 25% underwent revision for this reason. After the first stage, 92% were considered infection-free. There were 84% of patients who underwent second-stage reimplantation of a total femoral arthroplasty using a modular megaprosthetic implant. Infection-free implant survival was 85% after 2 years and 53% after 5 years. There were 44% of patients who underwent amputation after a median time of 40 months (range, 2-110). Most commonly, coagulase-negative staphylococci were cultured at first-stage surgery, while polymicrobial growth was most common at reinfection., Conclusion: Total femur spacers can lead to infection control in over 90% of cases with a reasonable complication rate for the spacer itself. However, the reinfection and subsequent amputation rate after second-stage megaprosthetic total femoral arthroplasty is around 50%., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Dislocation is a major complication of revision THA after two-stage exchange for periprosthetic joint infection (PJI). The likelihood of dislocation can be particularly high if megaprosthetic proximal femoral replacement (PFR) has been performed during a second-stage reimplantation. Dual-mobility acetabular components are an established way of reducing the instability risk in revision THA; however, the likelihood of dislocation for dual-mobility reconstructions in the setting of a two-stage PFR has not been studied systematically, although patients with these reconstructions might be at an increased risk., Questions/purposes: (1) What is the risk of dislocation and revision for dislocation in patients who underwent PFR with a dual-mobility acetabular component as part of two-stage exchange for hip PJI? (2) What is the risk of all-cause implant revision and what other procedures were performed (apart from revision for a dislocation) in these patients? (3) What potential patient-related and procedure-related factors are associated with dislocation?, Methods: This was a retrospective study from a single academic center including procedures performed between 2010 and 2017. During the study period, 220 patients underwent two-stage revision for chronic hip PJI. Two-stage revision was the approach of choice for chronic infections, and we did not perform single-stage revisions for this indication during the study period. Thirty-three percent (73 of 220) of patients underwent second-stage reconstruction with a single-design, modular, megaprosthetic PFR because of femoral bone loss, using a cemented stem. A cemented dual-mobility cup was the approach of choice for acetabular reconstruction in the presence of a PFR; however, 4% (three of 73) were reconstructed with a bipolar hemiarthroplasty to salvage an infected saddle prosthesis, leaving 70 patients with a dual-mobility acetabular component and a PFR (84% [59 of 70]) or total femoral replacement (16% [11 of 70]). We used two similar designs of an unconstrained cemented dual-mobility cup during the study period. The median (interquartile range) patient age was 73 years (63 to 79 years), and 60% (42 of 70) of patients were women. The mean follow-up period was 50 ± 25 months with a minimum follow-up of 24 months for patients who did not undergo revision surgery or died (during the study period, 10% [seven of 70] died before 2 years). We recorded patient-related and surgery-related details from the electronic patient records and investigated all revision procedures performed until December 2021. Patients who underwent closed reduction for dislocation were included. Radiographic measurements of cup positioning were performed using supine AP radiographs obtained within the first 2 weeks after surgery using an established digital method. We calculated the risk for revision and dislocation using a competing-risk analysis with death as a competing event, providing 95% confidence intervals. Differences in dislocation and revision risks were assessed with Fine and Gray models providing subhazard ratios. All p values were two sided and the p value for significance was set at 0.05., Results: The risk of dislocation (using a competing-risks survivorship estimator) was 17% (95% CI 9% to 32%) at 5 years, and the risk of revision for dislocation was 12% (95% CI 5% to 24%) at 5 years among patients treated with dual-mobility acetabular components as part of a two-stage revision for PJI of the hip. The risk of all-cause implant revision (using a competing-risk estimator, except for dislocation) was 20% (95% CI 12% to 33%) after 5 years. Twenty-three percent (16 of 70) of patients underwent revision surgery for reinfection and 3% (two of 70) of patients underwent stem exchange for a traumatic periprosthetic fracture. No patients underwent revision for aseptic loosening. We found no differences in patient-related and procedure-related factors or acetabular component positioning for patients with dislocation with the numbers available; however, patients with total femoral replacements had a higher likelihood of dislocation (subhazard ratio 3.9 [95% CI 1.1 to 13.3]; p = 0.03) and revision for a dislocation (subhazard ratio 4.4 [95% CI 1 to 18.5]; p = 0.04) than those who received PFR., Conclusion: Although dual-mobility bearings might be an intuitive potential choice to reduce the dislocation risk in revision THA, there is a considerable dislocation risk for PFR after two-stage surgery for PJI, particularly in patients with total femoral replacements. Although the use of an additional constraint might appear tempting, published results vary tremendously, and future studies should compare the performance of tripolar constrained implants to that of unconstrained dual-mobility cups in patients with PFR to reduce the risk of instability., Level of Evidence: Level III, therapeutic study., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2023 by the Association of Bone and Joint Surgeons.)

Distal humeral replacement (DHR) is a limb-salvage option for the endoprosthetic reconstruction of bone defects following the resection of a primary bone sarcoma. As primary bone sarcomas are only occasionally located around the distal humerus, there is a paucity of information regarding postoperative function, and patients' resumption of sporting activities. With advances in diagnostics and in surgical and oncological treatment leading to an increased patient life expectancy and higher quality of life, patients' functional outcome and return to sports activities are of increasing interest. Between 1997 and 2021, a total of 24 patients underwent DHR with a single-design modular implant at a tertiary sarcoma center. A total of 14 patients who died of their disease were excluded, leaving a study cohort of 10 patients, with a median age of 30 years on the day of surgery (IQR 20-37). At the last follow-up, after a median of 230 months (IQR 165-262), the median MSTS was 19 (IQR 13-24), the median TESS was 79 (IQR 66-87), the median SEV was 38% (IQR 24-53), the median TS was 6 (IQR 4-7), and the median WAS was 3 (IQR 1-8). Among the variables of gender, surgery on the dominant extremity, intraoperative nerve resection, extra-articular tumor resection, chemotherapy, radiotherapy, and revision surgeries, none were associated with a better/lower functional outcome score or return to sports activities. However, a higher level of sports performance prior to diagnosis (WAS > 10) was associated with a higher level of sports performance postoperatively ( p = 0.044)., Competing Interests: G.G. certifies that he holds a patent for the silver coating of a metallic prosthesis, and receives payments from Implantcast GmbH (Buxtehude, Germany). C.T. and N.D. certify that they have received travel expenses from Implantcast GmbH (Buxtehude, Germany). All other authors declare that they have no competing interest.

We present a high-energy laser source consisting of an ultrafast thin-disk amplifier followed by a nonlinear compression stage. At a repetition rate of 5 kHz, the drive laser provides a pulse energy of up to 200 mJ with a pulse duration below 500 fs. Nonlinear broadening is implemented inside a Herriott-type multipass cell purged with noble gas, allowing us to operate under different seeding conditions. Firstly, the nonlinear broadening of 64 mJ pulses is demonstrated in an argon-filled cell, showing a compressibility down to 32 fs. Finally, we employ helium as a nonlinear medium to increase the energy up to 200 mJ while maintaining compressibility below 50 fs. Such high-energy pulses with sub-50 fs duration hold great promise as drivers of secondary sources.

(1) Background: Prior to revision hip (THA) or knee arthroplasty (TKA), periprosthetic low-grade infection (PJI) should be ruled out. Despite advances in preoperative diagnosis, unsuspected positive cultures (UPCs) may occur in initially planned aseptic revisions. Particularly, single UPCs pose a diagnostic and therapeutic dilemma, as their impact on outcome is unclear and recommendations are heterogeneous. This review investigates the frequency of single UPCs and their impact on implant survivorship. (2) Methods: In July 2022, a comprehensive literature search was performed using PubMed and Cochrane Library search. In total, 197 articles were screened. Seven retrospective studies with a total of 5821 cases were able to be included in this review. (3) Results: Based on the cases included, UPCs were found in 794/5821 cases (14%). In 530/794 cases (67%), the majority of the UPCs were single positive. The most commonly isolated pathogens were coagulase negative Staphylococci and Cutibacterium acnes . Five of seven studies reported no influence on revision- or infection-free survival following a single positive culture. In two studies, single UPCs following THA revision were correlated with subsequent re-revision for PJI. (4) Conclusions: Single UPCs of a non-virulent pathogen following presumed aseptic TKA revision may be interpreted as contaminants. A single UPC following THA revision may be a risk factor for subsequent PJI. The role of systemic antibiotic treatment remains unclear, but it should be considered if other risk factors for PJI are present.

Background: Improved patient and limb survival rates have led to an increased interest in the functional outcome and return to sports of patients undergoing megaprosthetic reconstruction in musculoskeletal oncology. This study evaluates the functional outcome and postoperatively performed level of sports in patients undergoing proximal humeral replacement (PHR) following resection of a primary bone sarcoma and identifies potential beneficial and limiting factors., Patients and Methods: Between 2007 and 2020, a total of 606 patients underwent resection of a primary bone sarcoma and reconstruction with a single-design modular implant. For 112 (18%) patients, the location of the tumour was the proximal humerus. Exclusion criteria were death (n = 65), patients living overseas (n = 8), and subsequent amputation (n = 1), leaving 38 patients for evaluation, of whom 32 were available for the study (13 women, median age 42 years). Clinical data regarding oncological and surgical treatment as well as subsequent complications were obtained from the patients' electronic medical records. Functional outcome was determined using the Musculoskeletal Tumor Society Score (MSTS) and Toronto Extremity Salvage Score (TESS) as well as the Subjective Shoulder Value (SSV). Return to sports was assessed using the Tegner Activity Score (TS) and the modified Weighted Activity Score (WAS)., Results: At the last follow-up after a median of 30 months (IQR 22-58), median MSTS was 18 (IQR 12-24), median TESS was 80% (IQR 69-87), median SSV was 35% (IQR 10-58), median TS was 5 (IQR 4-6) and median WAS was 5 (IQR 0-10). Preservation of the axillary nerve, a reverse shoulder reconstruction and a WAS of > 10 prior to surgery were associated with better functional outcome and return to sports activity scores., Conclusion: Following PHR, good to excellent functional outcomes are possible, and patients regularly return to participate in sports activities-most commonly in low-impact types of sports, but some individuals are even able to participate in high-impact sports activities., Level of Evidence: IV., (© 2022. The Author(s).)

Background: Synovial fluid markers (synovial leukocyte count and differential) have been shown to be most accurate in diagnosing prosthetic joint infection (PJI). An inverse correlation for synovial leukocyte count and synovial pH is known assuming that leukocyte metabolism causes synovial fluid acidosis. This study's purpose is to analyze the use of synovial pH as a potential diagnostic marker for PJI., Materials and Methods: 92 patients who presented with painful total joint arthroplasty (TJA) of the hip (THA; n = 25) or knee (TKA, n = 67) were prospectively investigated. In our cohort 33% (30/92) had PJI and 67% (62/92) were diagnosed non-infected based on the modified Musculoskeletal Infection Society (MSIS) criteria of 2018. Receiver operating curves and the Youden's index were used to define an ideal cut-off value for synovial pH and the sensitivity and specificity were calculated using cross-tables. Additionally, the sensitivity and specificity were calculated for synovial white blood cell (WBC) count (cut-off > 3000 leukocytes) and percentage of neutrophils (PMN%, cut-off > 80%)., Results: The median synovial pH level was significantly lower in the group with chronic PJI compared to implants with aseptic failure (7.09 vs. 7.27; p < 0.001). The calculated optimal cut-off value was 7.11 (AUC 0.771) with a sensitivity of 53% and specificity of 89%. However, the sensitivity and specificity of synovial WBC count were 90% and 88% and for synovial PMN% 73% and 98%, respectively., Conclusion: Synovial pH may be a useful adjunct parameter in the diagnosis of chronic PJI after hip or knee arthroplasty, but showed low sensitivity in this preliminary cohort. Future studies with larger numbers are needed., Level of Evidence: 2a, diagnostic study. Trial registration German Clinical Trials Register (Registration number: DRKS00021038)., (© 2022. The Author(s).)

We demonstrate pulse compressibility from 840 fs to 38 fs of 10 mJ pulses from a thin-disk amplifier at a repetition rate of 3 kHz after nonlinear broadening in a multipass cell. In addition, the temporal-intensity contrast is enhanced via nonlinear ellipse rotation of more than a factor 50 with an optical efficiency of 56%. We believe this is the first published experimental combination of multipass cell-based nonlinear compression and nonlinear ellipse rotation-based contrast enhancement preserving both pulse compressibility and beam quality.

Purpose: Megaprosthetic distal femoral reconstruction (DFR) is a limb-salvage procedure to address bone loss following two-stage revision for periprosthetic knee joint infection (PJI). The purpose of this study was to analyze the survival of DFR compared to hinged total knee arthroplasty (TKA). It was hypothesized that DFR was associated with a poorer survival., Methods: In this retrospective single-center study, 97 subjects who underwent two-stage revision of chronic knee PJI were included. Among these, 41 were DFR. The diagnosis of PJI was established using the Musculoskeletal Infection Society (MSIS) criteria. Implant survival was calculated using Kaplan-Meier method and compared with the log-rank test as well as multivariate Cox regression at a minimum follow-up period of 24 months., Results: The median follow-up period was 59 (interquartile range (IQR) 45-78) months. Overall, 24% (23/97) of patients required revision surgery for infection. The infection-free survival of rotating hinge revision TKA was 93% (95% Confidence Interval (CI) 86-100%) at five years compared to 50% (95% CI 34-66%) for DFR. In multivariate analysis, the risk factors for reinfection were DFR reconstruction (HR 4.7 (95% CI 1-22), p = 0.048), length of megaprosthesis (HR 1.006 (95% CI 1.001-1.012), p = 0.032) and higher BMI (HR 1.066, 95% CI 1.018-1.116), p = 0.007). 10% (4/41) of patients undergoing DFR underwent amputation to treat recurrent infection., Conclusion: Megaprosthetic DFR as part of a two-stage exchange for PJI is a salvage treatment that has a high risk for reinfection compared to non-megaprosthetic TKA. Patients must therefore be counseled accordingly., Level of Evidence: Retrospective observational study, Level IV., (© 2021. The Author(s).)

Megaprosthetic reconstruction of segmental bone defects following sarcoma resection is a frequently chosen surgical approach in orthopedic oncology. While the use of megaprostheses has gained popularity over the last decades and such implants are increasingly used for metastatic reconstructions and in non-tumor cases, there still is a high risk of long-term complications leading to revision surgery. This article investigates current implant survivorship, frequency and types of complications as well as functional outcomes of upper and lower limb megaprosthetic reconstructions.

We aimed to evaluate the functional outcome and endoprosthetic complications following the Bateman-type soft tissue reconstruction around proximal or total humeral replacements in patients undergoing resection of a primary malignant bone tumor. Between September 2001 and December 2018, a total of 102 patients underwent resection of a primary malignant bone tumor and subsequent reconstruction with a modular humeral megaprosthesis in our department. Fifteen (15%) of these patients underwent a Bateman-type soft tissue reconstruction and were included in this retrospective study. The median Musculoskeletal Tumor Society (MSTS) score was 21, the median Toronto Extremity Salvage Score (TESS) was 70, and the median American Shoulder and Elbow Surgeons (ASES) score was 72. Fifty-three percent (8/15) of all patients required a revision surgery after a median time of 6 months. There were 2 soft tissue failures, 3 infections and 3 tumor recurrences. The revision-free implant survivorship amounted to 53% (95% confidence interval (CI) 28-81) after 1 year and 47% (95% CI 22-73) at last follow-up. The Bateman-type reconstruction is a feasible option for soft tissue reconstruction but functional outcome is overall limited and the risk for revision surgery within the first postoperative year is high.

(1) Background: Modular megaprosthetic reconstruction using a proximal humerus replacement has emerged as a commonly chosen approach after bone tumor resection. However, the long-term risk for revision surgery is relatively high. One factor that might be associated with mechanical failures is periprosthetic osteolysis around the stem, also known as stress shielding. The frequency, potential risk factors, and the effect on implant survival are unknown. (2) Methods: A retrospective single-center study of 65 patients with sarcoma who underwent resection of the proximal humerus and subsequent reconstruction with a modular endoprosthesis. Stress shielding was defined as the development of bone resorption around the prosthesis stem beginning at the bone/prosthesis interface. The extent of stress shielding was measured with a new method quantifying bone resorption in relation to the intramedullary stem length. All patients had a minimum follow-up of 12 months with conventional radiographs available and the median follow-up amounted to 36 months. (3) Results: Stress shielding was observed in 92% of patients (60/65). The median longitudinal extent of stress shielding amounted to 14% at last follow-up. Fifteen percent (10/65) showed bone resorption of greater than 50%. The median time to the first radiographic signs of stress shielding was 6 months (IQR 3-9). Patients who underwent chemotherapy (43/65) showed a greater extent of stress shielding compared to those without chemotherapy. Three percent (2/65) of patients were revised for aseptic loosening, and one patient had a periprosthetic fracture (1/65, 1.5%). All these cases had >20% extent of stress shielding (23-57%). (4) Conclusions: Stress shielding of the proximal humerus after shoulder reconstruction with modular megaprosthesis is common. It occurs within the first year of follow-up and might be self-limiting in many patients; however, about one third of patients shows progression beyond the first year. Still, mechanical complications were rare, but stress shielding might be clinically relevant in individual cases. The extent of stress shielding was increased in patients who underwent perioperative chemotherapy. Stress shielding can be quantified with an easy method using the stem length as a reference.

The accurate preoperative diagnosis of periprosthetic joint infection (PJI) of total knee arthroplasty (TKA) can be difficult despite the use of a combination of serum and synovial markers. In such inconclusive cases, incisional open biopsy might be considered. This study investigates the usefulness of biopsies in patients with inconclusive diagnostic findings. We retrospectively identified 63 patients who underwent incisional biopsy for chronic PJI in the operation theatre following TKA revision between 2010 and 2018 after inconclusive preoperative diagnostics for PJI. In all cases, 5 independent biopsies were taken. Results from open biopsy for PJI were analyzed for diagnostic accuracy using the intraoperative results from following revision surgery as gold standard. 27 patients (43%) had a positive culture taken during biopsy. 15 cases (24%) met the diagnostic criteria for a chronic PJI. Most common organisms were Coagulase-negative staphylococci (67%) and Cutibacterium acnes (30%). Compared to the findings during revision surgery, biopsies showed a sensitivity of 47% and a specificity of 77% for PJI. Open incisional biopsy following inconclusive serum- and synovial diagnostics for low grade PJI may be considered for identification of microorganisms. Due to its low sensitivity and moderate specificity found in the present cohort, microbiological analysis should be combined with additional diagnostic markers and histological investigation.Level of Evidence. Retrospective cohort study (Level III).

D-dimer has been included in the criteria by the Musculoskeletal Infection Society in 2018 as a novel parameter to diagnose prosthetic joint infection (PJI). However, it is unclear how D-dimer levels change in between stages of a two-stage exchange. We prospectively investigated 30 patients who underwent a two-stage exchange using a spacer for PJI. D-Dimer, CRP and IL-6 were collected before first and second stage surgery and the difference (Δ) in between stages was calculated. The levels of plasma D-Dimer did not change from first to second stage surgery (2770 ng/ml (IQR, 1600-3770 ng/ml) versus 2340 ng/ml (IQR, 1270-4100 ng/ml); p = 0.8) while CRP (4.0 mg/dl (IQR, 1.7-5.5 mg/dl) versus 0.6 mg/dl (IQR, 0.5-0.8 mg/dl); p < 0.001) and IL-6 (21 pg/ml (IQR, 10-29 pg/ml) versus 6 pg/ml (4-9 pg/ml); p < 0.001) decreased. The ΔD-dimer between both stages was 300 ng/ml (range: - 2820 to 4280 ng/ml), the median ΔCRP was - 3.4 mg/dl (IQR, - 1.2 to - 4.8 mg/dl) and ΔIL-6 was - 13 pg/ml (IQR, - 4 to - 20 pg/ml). In 15 of 30 cases (50%) the D-dimer level increased between both stages, whereas the level of CRP (93%; 28/30) and IL-6 (96%; 28/29) decreased in most patients. As the level of serum D-dimers varies greatly, lacks a uniform decrease and does not identify persisting infection, surgeons should be cautious when using it at the timing of reimplantation.

Background: Reactive arthritis following infection with chlamydia is a rare but important differential diagnosis in atraumatic joint swelling. A delayed diagnosis often leads to prolonged periods of absence from physical activity. This can have serious consequences, especially for the career of competitive athletes., Objectives: Recommendation for the clinical management of postinfectious reactive arthritis for rapid diagnosis and targeted treatment in the symptomatic clinical course., Materials and Methods: Review of the literature on the topics "chlamydia", "reactive arthritis", "postinfectious arthritis" and "sexually acquired reactive arthritis", including presentation of two clinical cases of postinfectious reactive arthritis after chlamydia infection from competitive sports., Results and Conclusion: Reactive arthritis following chlamydia infection in competitive athletes is a rare entity. However, it can be accompanied by far-reaching individual consequences, especially with regard to possible downtime in sports. Long-term consequences such as chronic joint damage in maintained synovitis must also be considered. In order to make a diagnosis, a specific anamnesis and the direct detection of the pathogen in the specimen of synovial fluid by polymerase chain reaction is essential. This allows a reliable diagnosis to be made with immediate initiation of therapy. However, a prolonged course of the disease cannot be excluded even if therapy is started in due time.

The tenosynovial giant cell tumor is a rare disease of the joint mucosa, tendon sheaths and bursa. We report on the rare constellation of an intraosseous manifestation of the proximal tibia of a lower leg stump after Burgess amputation as a result of a locally uncontrollable tenosynovial giant cell tumor of the upper ankle. The curettage of the local findings and operative stabilization through an intramedullary composite osteosynthesis led to an early rehabilitation of the exoprosthesis care with regaining patient autonomy.

Background: Periprosthetic shoulder infections are devastating complications after shoulder arthroplasty. A potential treatment concept is a two-stage prosthesis exchange. Data are sparse in terms of clinical outcome, including infection-free survival and patient satisfaction after this procedure. In the present study, we investigated recurrence of infection, revision-free survivorship and clinical outcome following two-stage revision due to periprosthetic shoulder infection. Furthermore, reasons for poor outcome were analyzed., Methods: Sixteen patients undergoing two-stage revision after shoulder joint infection were retrospectively identified. Recurrence of infection was analyzed by Kaplan-Meier survival curve. Clinical outcome was quantified with subjective shoulder value (SSV), "quick" Disabilities of the Arm, Shoulder and Hand (qDASH) and Rowe score. Range of motion (ROM) was measured pre- and postoperatively. Postoperative scores and ROM were compared in a subgroup analysis according to different reimplanted prosthesis types., Results: The reinfection-free implant survival was 81% after one year and at final follow-up (FU; mean of 33.2 months). The overall revision-free survival amounted to 56% after one year and at final FU. Patients who received reverse shoulder arthroplasty (RSA) as part of reimplantation had less disability and long-term complications. This group demonstrated better subjective stability and function compared to patients revised to megaprostheses or large-head hemiarthroplasties., Conclusions: Two-stage revision following periprosthetic joint infection of the shoulder allows appropriate infection control in the majority of patients. However, the overall complications and revision rates due to mechanical failure or reinfection are high. Reimplantation of RSA seem superior to alternative prosthesis models in terms of function and patient satisfaction. Therefore, bone-saving surgery and reconstruction of the glenoid may increase the likelihood of reimplantation of RSA and potentially improve outcome in the case of infection-related two-stage revision of the shoulder.

Background: Differentiation between traumatic osteoporotic and non-osteoporotic vertebral fractures is crucial for optimal therapy planning. We postulated that the morphology of the posterior edge of the cranial fragment of A3 vertebral fractures is different in these entities. Therefore, the purpose of this study is to develop and validate a simple method to differentiate between osteoporotic and non-osteoporotic A3 vertebral fractures by morphological analysis., Methods: A total of 86 computer tomography scans of AO Type A3 (cranial burst) vertebral body fractures (52 non-osteoporotic, 34 osteoporotic) were included in this retrospective study. Posterior edge morphology was analyzed using the sagittal paramedian slice with the most prominent shaped bulging. Later, the degree of bulging of the posterior edge fragment was quantified using a geometric approach. Additionally, the Hounsfield units of the broken vertebral body, the vertebra above, and the vertebra below the fracture were measured., Results: We found significant differences in the extent of bulging comparing osteoporotic and non-osteoporotic fractures in our cohort. Using the presented method, sensitivity was 100%, specificity was 96%. The positive predictive value (PPV) was 94%. In contrast, by evaluating the Hounsfield units, sensitivity was 94%, specificity 94% and the PPV was 91%., Conclusions: Our method of analysis of the bulging of the dorsal edge fragment in traumatic cranial burst fractures cases allows, in our cases, a simple and valid differentiation between osteoporotic and non-osteoporotic fractures. Further validation in a larger sample, including dual-energy X-ray absorptiometry (DXA) measurements, is necessary.

Background-Postoperative serum C-reactive protein (CRP) is an important diagnostic parameter for systemic inflammation and reflects surgical trauma. While trends and normal trajectories after total knee (TKA) or hip arthroplasty (THA) are established, there is no reference standard for shoulder arthroplasty (SA). Therefore, the aim of this study was to research CRP trends and influencing factors following SA. Methods-This retrospective study analyzed postoperative serum CRP levels and trajectories in 280 patients following SA. Influence of prosthesis design, sex, operating time, BMI, and humeral augmentation with bone cement were analyzed using descriptive statistics and (non-) parametric testing. Results-There is a CRP trend with a peak on day two or three, with a subsequent decrease until day seven. Reverse and stemmed prostheses show a statistically higher CRP peak than stemless prostheses or hemiarthroplasties (HA). There was no influence of gender, body mass index (BMI), operating time, or bone cement. Conclusion-The presented findings may contribute to a better understanding of the postoperative CRP course after SA. The results of this retrospective study should be validated by a prospective study design in the future.

We present an ultrafast thin-disk based multipass amplifier operating at a wavelength of 1030 nm, designed for atmospheric research in the framework of the Laser Lightning Rod project. The CPA system delivers a pulse energy of 720 mJ and a pulse duration of 920 fs at a repetition rate of 1 kHz. The 240 mJ seed pulses generated by a regenerative amplifier are amplified to the final energy in a multipass amplifier via four industrial thin-disk laser heads. The beam quality factor remains ∼ 2.1 at the output. First results on horizontal long-range filament generation are presented.

Background: To investigate the influence of shoulder immobilization on daily physical activity., Introduction: The harmful effect of sedentary behavior does not receive much attention in orthopedic surgery even though immobilization, especially of the lower extremity, has been associated with reduced physical activity. Immobilization of the shoulder is common after reconstructive shoulder surgery and could also potentially lead to reduced physical activity and have a negative effect on a patient's general health., Method: Twenty-one healthy volunteers were immobilized in an orthosis (DJO Ultrasling III) for 10 h on two consecutive days. In the following week, activity was measured on the same days without the orthosis. Activity including gait cycles per minute and total gait cycles per day was measured by accelerometer based step count StepWatchTMActivity Monitor. Average age was 26 +/- 3 years. A questionnaire was administered to evaluate subjective activity., Results: Participants wearing the shoulder orthosis were significantly less active than without immobilization by 2227.5 gait cycles/day (5501.2 with SO, 7728.7 without SO). Also, significantly more time in sedentary behavior occurred (< 400 steps/h) when the shoulder was immobilized. Patients were significantly more active without shoulder orthosis in medium level activities (800-999 steps/h). Differences for low (400-799 steps/h) and high activity levels (> 1000 steps/h) were not statistically significant. Subjective limitations while wearing the orthosis were graded at 2.343 on a scale of 0-4., Conclusion: Results of this study show that even in young, healthy volunteers immobilization of the shoulder in an orthosis for 2 days leads to significantly reduced activity levels. A negative influence on general health, especially in older patients who are immobilized for up to 6 weeks, can potentially occur. Promoting physical activity during the immobilization period should be part of rehabilitation after injuries/surgery of the shoulder., Trial Registration: Retrospectively registered in DRKS (DRKS00017636).

Objectives: To investigate the prevalence of shoulder-related acute and overuse injuries in triathletes and examine the role of possible risk factors, in order to identify potential preventive measures., Methods: We performed a retrospective epidemiologic study of 193 amateur triathletes between June and August 2013 and evaluated their competition and training habits, as well as the presence of acute and overuse injuries of the shoulder sustained during the past 12 months. Contingency tables were analyzed using Pearson's chi-squared test. Normally distributed data were compared with the independent samples t-test, while non-parametric analyses were performed with the Mann-Whitney U test. Binary logistic regression was used to identify important predictors of injuries., Results: 12 participants (6%) sustained acute injuries and 36 athletes experienced an overuse injury. The acute injury rate amounted to 0.11 per 1000 hours of training and the overuse injury rate to 0.33 per 1000 hours of training. There was no association between athletes' age, height, weight, BMI, a history of shoulder complaints or triathlon experience in years and acute or overuse injuries. Male athletes had a trend for sustaining more acute injuries then female athletes (8% vs. 2%, p = 0.079). Athletes with acute injuries spent a significantly higher amount of time per week doing weight training (p = 0.007) and had a trend for a higher weekly duration of cycling training (p = 0.088). Athletes with overuse injuries participated in a significantly higher number of races compared to athletes without overuse injuries (p = 0.005). The regular use of paddles was associated with a significantly higher rate of overuse injuries (24% vs. 10%, p = 0.014)., Conclusion: The regular use of paddles during swimming training appears to be a risk factor for the development of overuse injuries, while an increased duration of weight and cycling training seems to be associated with a higher rate of acute injuries., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: GG is board member of 2 international societies (EMSOS, ISOLS) and receives royalties from 1 patent (unrelated to this work). DL is a consultant for ConMed Deutschland GmbH and has received reimbursements for travel and accommodation expenses from ConMed (unrelated to this work). This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Background: There is currently no consensus regarding the optimal surgical treatment method for patients with recurrent patella instability. Our goal was to evaluate the long-term results of combined arthroscopic medial reefing and lateral release, to identify possible risk factors for recurrent dislocations and residual complaints after surgical treatment and to assess functional outcome., Methods: We performed a retrospective study of 38 patients (43 knees) treated with all-inside technique between 2001 and 2010. The functional outcome was evaluated with the Kujala score, while pain intensity was scored on a visual analogue scale (VAS). Contingency tables were analysed with Fisher's exact test. Non-parametric analyses were carried out with the Mann-Whitney U and the Wilcoxon signed-rank test. Survival curves were calculated with the Kaplan-Meier method and compared with the log-rank test., Results: The median age at surgery was 16 years (range, 9-44 years) and the median follow-up amounted to 9.7 years (range, 4.7-14.7 years). Residual complaints were present in 34 cases (79%). Patients with residual complaints had a trend for a higher body mass index (BMI) at surgery (25.7 vs. 21.6, P = .086). Twenty-two cases had recurrent dislocation after a median interval of 30 months. The probability of recurrent dislocations amounted to 16% after 1 year and 52% after 10 years. There were no significant differences in the presence of residual complaints (P = .721) and median VAS score (P = .313) between patients with or without recurrent dislocation. Patients with recurrent dislocations had a trend towards younger age at surgery (15 vs. 18 years, P = .076). The median Kujala score of the affected knee was 81. Patients with recurrent dislocations had a significantly lower score compared to patients without recurrent dislocations (67 vs. 91, P < .001)., Conclusions: The combined arthroscopic lateral release with medial reefing does not appear to be an adequate treatment for patients with chronic patellar instability in long-term follow-up. Younger patients might be at a higher risk for recurrent dislocations, while a higher BMI at surgery might be associated with residual complaints.

We present the generation of optical pulses with a spectral range of 500-2400 nm and energies up to 10 µJ at 1 kHz repetition rate by cascaded second-order nonlinear interaction of few-cycle pulses in beta-barium borate (BBO). Numerical simulations with a 1D+time split-step model are performed to explain the experimental findings. The large bandwidth and smooth spectral amplitude of the resulting pulses make them an ideal seed for ultra-broadband optical parametric chirped pulse amplification and an attractive source for spectroscopic applications.

On the quest towards reaching petawatt-scale peak power light pulses with few-cycle duration, optical parametric chirped pulse amplification (OPCPA) pumped on a time scale of a few picoseconds represents a very promising route. Here we present an experimental demonstration of few-ps OPCPA in DKDP, in order to experimentally verify the feasibility of the scheme. Broadband amplification was observed in the wavelength range of 830-1310 nm. The amplified spectrum supports two optical cycle pulses, at a central wavelength of ~920 nm, with a pulse duration of 6.1 fs (FWHM). The comparison of the experimental results with our numerical calculations of the OPCPA process showed good agreement. These findings confirm the reliability of our theoretical modelling, in particular with respect to the design for further amplification stages, scaling the output peak powers to the petawatt scale.

In an optically synchronized short-pulse optical-parametric chirped-pulse amplification (OPCPA) system, we observe a few-100 fs-scale timing jitter. With an active timing stabilization system slow fluctuations are removed and the timing jitter can be reduced to 100 fs standard deviation (Std). As the main source for the timing fluctuations we could identify air turbulence in the stretcher-compressor setup inside the chirped pulse amplification (CPA) pump chain. This observation is supported by theoretical investigation of group delay changes for angular deviations occurring between the parallel gratings of a compressor or stretcher, as they can be introduced by air turbulence.

We present a chirped pulse amplification (CPA) system based on diode-pumped Yb:YAG. The stretched ns-pulses are amplified and have been compressed to less than 900 fs with an energy of 200 mJ and a repetition rate of 10 Hz. This system is optically synchronized with a broadband seed laser and therefore ideally suited for pumping optical parametric chirped pulse amplification (OPCPA) stages on a ps-timescale.

We present what we believe to be the first terawatt diode-pumped laser employing single-crystalline Yb:CaF(2) as the amplifying medium. A maximum pulse energy of 420 mJ at a repetition rate of 1 Hz was achieved by seeding with a stretched femtosecond pulse 2 ns in duration, preamplified to 40 mJ. After recompression, a pulse energy of 197 mJ and a duration of 192 fs were obtained, corresponding to a peak power of 1 TW. Furthermore, nanosecond pulses containing an energy of up to 905 mJ were generated without optical damage.