Lateral rim variable angle locked plating versus tension band wiring of simple and complex patella fractures: a biomechanical study.

INTRODUCTION: Treatment of both simple and complex patella fractures is a challenging clinical problem. Although tension band wiring has been the standard of care, it can be associated with high complication rates. The aim of this study was to investigate the biomechanical performance of recently developed lateral rim variable angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures. MATERIALS AND METHODS: Sixteen pairs of human anatomical knees were used to simulate either two-part transverse simple AO/OTA 34-C1 or five-part complex AO/OTA 34-C3 patella fractures by means of osteotomies, with each fracture model created in eight pairs. The complex fracture pattern was characterized by a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral, and an inferior (central distal) fragment mimicking comminution around the distal patellar pole. The specimens with simple fractures were pairwise assigned for fixation with either tension band wiring through two parallel cannulated screws or a lateral rim variable angle locking plate. The knees with complex fractures were pairwise treated with either tension band wiring through two parallel cannulated screws plus circumferential cerclage wiring or a lateral rim variable angle locking plate. Each specimen was tested over 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive knee flexion within the range of 90° flexion to full extension. Interfragmentary movements were captured via motion tracking. RESULTS: For both fracture types, the articular displacements measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following the lateral rim variable angle locked plating compared with tension band wiring, p ≤ 0.01. CONCLUSIONS: From a biomechanical perspective, lateral rim variable angle locked plating of both simple and complex patella fractures provides superior construct stability versus tension band wiring under dynamic loading.

Imaging brain tissue architecture across millimeter to nanometer scales.

Mapping the complex and dense arrangement of cells and their connectivity in brain tissue demands nanoscale spatial resolution imaging. Super-resolution optical microscopy excels at visualizing specific molecules and individual cells but fails to provide tissue context. Here we developed Comprehensive Analysis of Tissues across Scales (CATS), a technology to densely map brain tissue architecture from millimeter regional to nanometer synaptic scales in diverse chemically fixed brain preparations, including rodent and human. CATS uses fixation-compatible extracellular labeling and optical imaging, including stimulated emission depletion or expansion microscopy, to comprehensively delineate cellular structures. It enables three-dimensional reconstruction of single synapses and mapping of synaptic connectivity by identification and analysis of putative synaptic cleft regions. Applying CATS to the mouse hippocampal mossy fiber circuitry, we reconstructed and quantified the synaptic input and output structure of identified neurons. We furthermore demonstrate applicability to clinically derived human tissue samples, including formalin-fixed paraffin-embedded routine diagnostic specimens, for visualizing the cellular architecture of brain tissue in health and disease.

Dense 4D nanoscale reconstruction of living brain tissue.

Three-dimensional (3D) reconstruction of living brain tissue down to an individual synapse level would create opportunities for decoding the dynamics and structure-function relationships of the brain's complex and dense information processing network; however, this has been hindered by insufficient 3D resolution, inadequate signal-to-noise ratio and prohibitive light burden in optical imaging, whereas electron microscopy is inherently static. Here we solved these challenges by developing an integrated optical/machine-learning technology, LIONESS (live information-optimized nanoscopy enabling saturated segmentation). This leverages optical modifications to stimulated emission depletion microscopy in comprehensively, extracellularly labeled tissue and previous information on sample structure via machine learning to simultaneously achieve isotropic super-resolution, high signal-to-noise ratio and compatibility with living tissue. This allows dense deep-learning-based instance segmentation and 3D reconstruction at a synapse level, incorporating molecular, activity and morphodynamic information. LIONESS opens up avenues for studying the dynamic functional (nano-)architecture of living brain tissue.

Two-staged management of ankle fracture-dislocations with a posterior fragment: computer-tomography-based classification, treatment and its outcome.

INTRODUCTION: Trimalleolar fractures are difficult to treat and malreduction can lead to functional impairment. Involvement of the posterior malleolus has a poor predictive value. Current computed-tomography (CT)-based fracture classifications led to an increase in fixation of the posterior malleolus. The aim of this study was to describe the functional outcome after a two-stage stabilisation with direct fixation of the posterior fragment in trimalleolar dislocation fractures. MATERIALS AND METHODS: In a retrospective study, all patients presenting with a trimalleolar dislocation fracture, an available CT scan, and a two-stage operative stabilisation including the posterior malleolus by a posterior approach were included. All fractures were treated with initial external fixator and delayed definitive stabilisation including fixation of the posterior malleolus. Next to clinical and radiological follow-up, outcome measures (Foot and Ankle Outcome Score (FAOS), Numeric Rating Scale (NRS), Activity of Daily Living (ADL), Hulsmans implant removal score) and complications were analysed. RESULTS: Between 2008 and 2019, of 320 trimalleolar dislocation fractures, 39 patients were included. Mean follow-up was 49 months (standard deviation (SD) 29.7, range 16-148). Mean age was 60 years (SD 15.3, 17-84) with 69% female patients. The mean FAOS was 93/100 (SD 9.7, 57-100), NRS 2 (interquartile range (IQR) 0-3) and ADL 2 (IQR 1-2). Four patients showed a postoperative infection, three re-operations had to be performed and implants were removed in 24 individuals. CONCLUSION: A two-stage procedure of trimalleolar dislocation fractures with in-direct reduction and fixation of the posterior tibial fragment through a posterior approach leads to good functional outcome scores with a low rate of complications.

Clavicular hook plate versus dog-bone technique for acute high-grade acromioclavicular joint dislocation: a retrospective cohort study comparing clinical outcome scores, complications, and costs.

INTRODUCTION: Arthroscopically assisted coracoclavicular (CC) ligament fixation techniques have been promoted as providing superior outcomes for the treatment of acute high-grade acromioclavicular joint (ACJ) dislocations. Nevertheless, there is a lack of high-level evidence for clinically relevant benefits. At our institute, orthopaedic surgeons use an arthroscopically assisted coracoclavicular ligament fixation technique (DB), while general trauma surgeons use a clavicular hook plate (cHP) technique. The aim of the study was to compare clinical outcomes, complication rates, and costs between the two groups. MATERIALS AND METHODS: The hospital database was searched for patients treated for acute traumatic high-grade (Rockwood Typ ≥ III) ACJ dislocation using either a cHP or arthroscopically assisted DB technique between 2010 and 2019. Seventy-nine patients could be included (56 patients in the cHP group and 23 in the DB group). QuickDASH scores, subjective shoulder value (SSV) scores, pain scores (numerical pain rating scale 10), and complication rates were retrospectively collected through phone interviews and by screening patient charts as well as surgical reports. Costs per patient were obtained from the hospital's accounting system. RESULTS: Mean follow-up was 54 ± 33.7 and 45 ± 21.7 months in the cHP and DB group, respectively. QuickDASH and SSV scores did not differ, but patients in the cHP group reported significantly lower pain scores (p = 0.033). More patients reported hypertrophic or disturbing scars (p = 0.49) and sensibility disturbances (p = 0.007) in the cHP group. Three patients suffered from a frozen shoulder in the DB group (p = 0.023). CONCLUSION: Patient-reported outcomes are excellent after long-term follow-up for both techniques. There are no clinically relevant differences in clinical outcome scores based on our results and a review of the literature. Both techniques certainly have their benefits regarding secondary outcome measures. LEVEL OF CLINICAL EVIDENCE: Level 3, retrospective cohort study.

Anterior variable-angle locked plating versus tension band wiring of simple and complex patella fractures - a biomechanical investigation.

BACKGROUND: The aim of this study was to investigate the biomechanical performance of novel anterior variable-angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures. METHODS: Sixteen pairs of human cadaveric knees were used to simulate two-part simple transverse AO/OTA 34-C1 and five-part complex AO/OTA 34-C3 patella fractures. The complex fracture pattern was characterized with a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral and an inferior fragment mimicking comminution around the distal patella pole. Eight pairs with simple fractures were split for fixation via either tension band wiring (TBW) through two parallel cannulated screws or anterior variable-angle locked plating, whereas other eight pairs with complex fractures were split for either TBW through two parallel cannulated screws plus circumferential cerclage wiring, or anterior variable-angle locked plating using a cortical caudo-cranial polar screw. Each specimen was tested over 5000 cycles with a range of motion from 90° flexion to full extension by pulling on the quadriceps tendon. Interfragmentary movements were captured by motion tracking. RESULTS: For both fracture types, the longitudinal and shear articular displacements, measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following anterior variable-angle locked plating versus TBW, p ≤ 0.01. CONCLUSIONS: From a biomechanical perspective, anterior locked plating of both simple and complex patella fractures resulted in less interfragmentary displacement under extended cyclic loading.

A hydraulic feedback loop between mesendoderm cell migration and interstitial fluid relocalization promotes embryonic axis formation in zebrafish.

Interstitial fluid (IF) accumulation between embryonic cells is thought to be important for embryo patterning and morphogenesis. Here, we identify a positive mechanical feedback loop between cell migration and IF relocalization and find that it promotes embryonic axis formation during zebrafish gastrulation. We show that anterior axial mesendoderm (prechordal plate [ppl]) cells, moving in between the yolk cell and deep cell tissue to extend the embryonic axis, compress the overlying deep cell layer, thereby causing IF to flow from the deep cell layer to the boundary between the yolk cell and the deep cell layer, directly ahead of the advancing ppl. This IF relocalization, in turn, facilitates ppl cell protrusion formation and migration by opening up the space into which the ppl moves and, thereby, the ability of the ppl to trigger IF relocalization by pushing against the overlying deep cell layer. Thus, embryonic axis formation relies on a hydraulic feedback loop between cell migration and IF relocalization.

Minimally invasive plate osteosynthesis for clavicle fractures.

OBJECTIVE: Treatment of comminuted clavicle shaft fractures with minimally invasive plate osteosynthesis (MIPO). INDICATIONS: Multifragmentary (≥ 2 intermediate fragments) clavicle shaft fractures with no need for anatomical reduction (AO 15.2B and 15.2C). Even simple fractures (AO 15.2A) with significant soft tissue injuries Tscherne grade I-III are suitable. CONTRAINDICATIONS: Medial or lateral clavicle fractures as well as simple fracture pattern where anatomical reduction is indispensable. SURGICAL TECHNIQUE: Short incision over the medial and lateral end of the main fracture fragments. Either medial or lateral epiperosteal plate insertion. Under image intensifier guidance, the plate is centered either superior or anteroinferior on the clavicle and fixed with a compression wire temporarily (alternatively by a cortical screw) in one of the most lateral holes. Fracture reduction (axis, length, and rotation) over the plate and preliminary fixation medially. After correct reduction has been achieved, further cortical screws and/or locking head screws can be inserted (lag before locking screws). Relative stability is achieved by applying a bridging technique. POSTOPERATIVE MANAGEMENT: No immobilization is needed. Patients are encouraged to perform functional rehabilitation with active and passive physical therapy. Loading is increased according to radiological signs of bony consolidation. RESULTS: In a retrospective evaluation from 2001-2021, 1128 clavicle osteosyntheses were performed, of which 908 (80.5%) were treated with plate osteosynthesis and 220 (19.5%) with titanium elastic nail (TEN). Of the 908 plate osteosyntheses, 43 (4.7%) were performed with the MIPO approach. Finally, 42 patients (35 men and 7 women; mean age of 44 ± 15 years) with 43 clavicle shaft fractures were analyzed. The operation was accomplished in 63 ± 28 min, and average fluoroscopy time was 45 ± 42 s. A collective of 27 patients could be evaluated after a median follow-up of 14 months (range 1-51 months). In all, 26 fractures healed in a timely manner. In 1 patient a pseudarthrosis occurred which was treated with re-osteosynthesis and cancellous bone grafting in an open technique. Another patient revealed a wound complication with need of operative wound revision 6 weeks after the index surgery. Further postoperative course was uneventful in both patients. All were pain-free and able to return to work. After an average of 17 ± 8 months, 18 hardware removals (66.7%) were performed.

Biomechanical Comparison of Intramedullary Versus Extramedullary Implants for Fixation of Simple Pertrochanteric Fractures.

OBJECTIVES: To evaluate the biomechanical performance of the intramedullary TFN-ADVANCED Proximal Femoral Nailing System (TFNA) versus the extramedullary Femoral Neck System (FNS) for fixation of simple pertrochanteric fractures in a human cadaveric model. METHODS: Ten human cadaveric femoral pairs were implanted pairwise with either TFNA or FNS. A simple pertrochanteric fracture OTA/AO 31-A1 was created and all specimens were biomechanically tested under progressively increasing cyclic loading until failure. Interfragmentary and bone-implant movements were monitored by motion tracking. RESULTS: Axial stiffness was comparable between TFNA and FNS, P = 0.34. Similarly, varus deformation, femoral head rotation around neck axis and implant migration remained without significant differences between TFNA and FNS after 3000 cycles (800 N peak load), P ≥ 0.10. However, cycles to 15-mm leg shortening were significantly higher for TFNA versus FNS, P < 0.01. CONCLUSIONS: From a biomechanical perspective, with its current design, FNS does not seem to be a valid alternative to TFNA for treatment of simple pertrochanteric fractures.

Clinical performance of the Femoral Neck System within 1 year in 125 patients with acute femoral neck fractures, a prospective observational case series.

INTRODUCTION: Osteosynthesis of femoral neck fractures (FNFs) is an important treatment option, especially for younger patients. We aimed to assess the rate of early implant-related complications in FNF osteosynthesis using the Femoral Neck System (FNS). PATIENTS AND METHODS: Consecutive patients diagnosed with displaced or nondisplaced FNFs were treated with FNS in this prospective, observational, multicenter investigation. Patients were followed up for minimally 3 months and up to 12 months if radiologic bone union and no pain was not achieved beforehand. Predefined treatment-related adverse events (AEs, defined as implant failure, loss of reduction, iatrogenic fractures, deep infection, and surgical revision), radiologic bone union, and patient-reported Harris hip score (HHS) and EQ-5D-5L index score were assessed. RESULTS: One hundred and twenty-five patients were included in the study. Thirty-eight (30.4%) fractures were displaced (Garden III and IV), and 37 (29.6%) were vertical fractures (Pauwels type III). Predefined treatment-related AE rate at 3 months was 8 patients, 6.4% (95% CI, 2.8-12.2), and at 12 months, 11 patients, 8.8% (95% CI, 4.5-15.2). Cumulative incidences of bone union were 68% at 3 months, 90% at 6 months, and 98% at 12 months. The mean changes of HHS and EQ-5D-5L index score between preinjury and at 12 months were -7.5 (95% CI, [ - 21.1] to [6.2]) and - 0.03 (95% CI, [ - 0.21] to [0.15]), respectively; neither were statistically significant. CONCLUSION: The current study on osteosynthesis of FNFs with the FNS resulted in treatment-related complication rates of 6.4% (95% CI, 2.8-12.2) at 3 months and 8.8% (95% CI, 4.5-15.2) at 12 months. On average, patients returned to preinjury function and quality of life. The current study may also indicate that the conventional wisdom of treating stable FNF in patients aged between 60 and 80 years with osteosynthesis may need to be reconsidered. REGISTRATION: The study is registered with ClinicalTrials.gov (registration number: NCT02422355).

Shoulder arthroplasty for proximal humeral fracture treatment: a retrospective functional outcome analysis.

PURPOSE: Following proximal humeral fractures hemiarthroplasty (HA) or reversed total shoulder arthroplasty (rTSA) are performed if osteosynthesis or conservative treatment is not possible. HA has been reported to result in decreased functional outcomes compared with rTSA. Secondary shoulder arthroplasty, performed after a different initial treatment, has also been associated with inferior outcomes. METHODS: Patients recieving a shoulder arthroplasty related to a proximal humeral fracture from 2010 to 2019 were included. A retrospective analysis of functional outcomes was performed using QuickDASH and subjective shoulder value (SSV). RESULTS: The mean [standard deviation (SD)] follow-up time among the 82 included patients was 48 (28) months. The mean age was 70 (10) years. The mean age for HA was significantly different from rTSA [57 (9) and 72 (21) years; p < .001]. The mean QuickDASH score for primary arthroplasty was 11 (2) versus 12 (16) for secondary arthroplasty (p = .313). The mean SSV for primary arthroplasty was 84 (22) versus 82 (17) for secondary arthroplasty (p = .578). The mean QuickDASH score for HA was 24 (36) versus 9 (15) for rTSA (p = .346). The mean SSV for HA was 70 (34) versus 86 (17) for rTSA (p = .578). CONCLUSION: Functional outcomes after fracture-related shoulder arthroplasty were excellent in an older population, even when performed secondarily after failed primary osteosynthesis or conservative treatment. No significant differences in shoulder function were identified between rTSA and HA, likely due to restrictive indications for HA.

Proximal humeral fracture-dislocation: Outcome analysis in osteosynthesis and arthroplasties.

PURPOSE: Proximal humeral fracture-dislocations (PHFD) are challenging to treat. In older patients, usually arthroplasty is performed. In younger patients, osteosynthesis is chosen. This study presents functional outcomes of these different treatment modalities. METHODS: All patients operated for PHFD from 2010 until 2017 were included. Osteosynthesis was performed in younger patients and if reconstruction was possible. Either an open deltopectoral approach or a minimal invasive plate osteosynthesis (MIPO) was performed. Hemiarthroplasty (HA) was done if reconstruction of the tubercles was possible, age was below 63 years and no signs of osteoarthritis were present. In all other cases, a reverse total shoulder arthroplasty (rTSA) was done. The primary endpoint was functional outcome assessed with the QuickDASH Score (QDS). Secondary outcomes were subjective shoulder value (SSV), complications, revisions, and conversion into arthroplasty. RESULTS: The mean follow-up of 40 patients was 56 ± 24 months. The mean QDS was 4.5 (0.6-9.1) and the mean SSV was 90 (80-98.6). Of these, 33 patients (mean age: 50) had an osteosynthesis, 25 were treated with MIPO. Only 18% were converted into an arthroplasty after a mean of 22 months. Among them, 7 patients received a primary arthroplasty (mean age: 68), no revisions were recorded. Subgroup analysis showed functional outcome deficits in avascular necrosis (AVN) compared to no AVN (p = 0.021), revision surgery compared to no revision (p = 0.040) and in HA compared to rTSA (p = 0.007). CONCLUSION: Both osteosynthesis and primary arthroplasty after PHFD can lead to good or even excellent functional outcome. Revision rates in osteosynthesis are high. Revision procedures or secondary conversion into arthroplasty after failed osteosynthesis decrease outcome scores significantly.

Three-dimensional visualization of planta clathrin-coated vesicles at ultrastructural resolution.

Biological systems are the sum of their dynamic three-dimensional (3D) parts. Therefore, it is critical to study biological structures in 3D and at high resolution to gain insights into their physiological functions. Electron microscopy of metal replicas of unroofed cells and isolated organelles has been a key technique to visualize intracellular structures at nanometer resolution. However, many of these methods require specialized equipment and personnel to complete them. Here, we present novel accessible methods to analyze biological structures in unroofed cells and biochemically isolated organelles in 3D and at nanometer resolution, focusing on Arabidopsis clathrin-coated vesicles (CCVs). While CCVs are essential trafficking organelles, their detailed structural information is lacking due to their poor preservation when observed via classical electron microscopy protocols experiments. First, we establish a method to visualize CCVs in unroofed cells using scanning transmission electron microscopy tomography, providing sufficient resolution to define the clathrin coat arrangements. Critically, the samples are prepared directly on electron microscopy grids, removing the requirement to use extremely corrosive acids, thereby enabling the use of this method in any electron microscopy lab. Secondly, we demonstrate that this standardized sample preparation allows the direct comparison of isolated CCV samples with those visualized in cells. Finally, to facilitate the high-throughput and robust screening of metal replicated samples, we provide a deep learning analysis method to screen the "pseudo 3D" morphologies of CCVs imaged with 2D modalities. Collectively, our work establishes accessible ways to examine the 3D structure of biological samples and provide novel insights into the structure of plant CCVs.

Bioselectivity of silk protein-based materials and their bio-inspired applications.

Adhesion to material surfaces is crucial for almost all organisms regarding subsequent biological responses. Mammalian cell attachment to a surrounding biological matrix is essential for maintaining their survival and function concerning tissue formation. Conversely, the adhesion and presence of microbes interferes with important multicellular processes of tissue development. Therefore, tailoring bioselective, biologically active, and multifunctional materials for biomedical applications is a modern focus of biomaterial research. Engineering biomaterials that stimulate and interact with cell receptors to support binding and subsequent physiological responses of multicellular systems attracted much interest in the last years. Further to this, the increasing threat of multidrug resistance of pathogens against antibiotics to human health urgently requires new material concepts for preventing microbial infestation and biofilm formation. Thus, materials exhibiting microbial repellence or antimicrobial behaviour to reduce inflammation, while selectively enhancing regeneration in host tissues are of utmost interest. In this context, protein-based materials are interesting candidates due to their natural origin, biological activity, and structural properties. Silk materials, in particular those made of spider silk proteins and their recombinant counterparts, are characterized by extraordinary properties including excellent biocompatibility, slow biodegradation, low immunogenicity, and non-toxicity, making them ideally suited for tissue engineering and biomedical applications. Furthermore, recombinant production technologies allow for application-specific modification to develop adjustable, bioactive materials. The present review focusses on biological processes and surface interactions involved in the bioselective adhesion of mammalian cells and repellence of microbes on protein-based material surfaces. In addition, it highlights the importance of materials made of recombinant spider silk proteins, focussing on the progress regarding bioselectivity.

In vitro reconstitution of Escherichia coli divisome activation.

The actin-homologue FtsA is essential for E. coli cell division, as it links FtsZ filaments in the Z-ring to transmembrane proteins. FtsA is thought to initiate cell constriction by switching from an inactive polymeric to an active monomeric conformation, which recruits downstream proteins and stabilizes the Z-ring. However, direct biochemical evidence for this mechanism is missing. Here, we use reconstitution experiments and quantitative fluorescence microscopy to study divisome activation in vitro. By comparing wild-type FtsA with FtsA R286W, we find that this hyperactive mutant outperforms FtsA WT in replicating FtsZ treadmilling dynamics, FtsZ filament stabilization and recruitment of FtsN. We could attribute these differences to a faster exchange and denser packing of FtsA R286W below FtsZ filaments. Using FRET microscopy, we also find that FtsN binding promotes FtsA self-interaction. We propose that in the active divisome FtsA and FtsN exist as a dynamic copolymer that follows treadmilling filaments of FtsZ.

CHD8 haploinsufficiency links autism to transient alterations in excitatory and inhibitory trajectories.

Mutations in the chromodomain helicase DNA-binding 8 (CHD8) gene are a frequent cause of autism spectrum disorder (ASD). While its phenotypic spectrum often encompasses macrocephaly, implicating cortical abnormalities, how CHD8 haploinsufficiency affects neurodevelopmental is unclear. Here, employing human cerebral organoids, we find that CHD8 haploinsufficiency disrupted neurodevelopmental trajectories with an accelerated and delayed generation of, respectively, inhibitory and excitatory neurons that yields, at days 60 and 120, symmetrically opposite expansions in their proportions. This imbalance is consistent with an enlargement of cerebral organoids as an in vitro correlate of patients' macrocephaly. Through an isogenic design of patient-specific mutations and mosaic organoids, we define genotype-phenotype relationships and uncover their cell-autonomous nature. Our results define cell-type-specific CHD8-dependent molecular defects related to an abnormal program of proliferation and alternative splicing. By identifying cell-type-specific effects of CHD8 mutations, our study uncovers reproducible developmental alterations that may be employed for neurodevelopmental disease modeling.

Double fixation for complex distal femoral fractures.

For complex distal femoral fractures, a single lateral locking compression plate or retrograde intramedullary nail may not achieve a stable environment for fracture healing. Various types of double fixation constructs have been featured in the current literature. Double-plate construct and nail-and-plate construct are two common double fixation constructs for distal femoral fractures. Double fixation constructs have been featured in studies on comminuted distal femoral fractures, distal femoral fracture with medial bone defects, periprosthetic fractures, and distal femoral non-union. A number of case series reported a generally high union rate and satisfactory functional outcomes for double fixation of distal femoral fractures. In this review, we present the state of the art of double fixation constructs for distal femoral fractures with a focus on double-plate and plate-and-nail constructs.

Let's Agree to Disagree on Operative versus Nonoperative (LADON) treatment for proximal humerus fractures: Study protocol for an international multicenter prospective cohort study.

BACKGROUND: The proximal humerus fracture is a common injury, but the optimal management is much debated. The decision for operative or nonoperative treatment is strongly influenced by patient specific factors, regional and cultural differences and the preference of the patient and treating surgeon. The aim of this study is to compare operative and nonoperative treatment of proximal humerus fractures for those patients for whom there is disagreement about optimal management. METHODS AND ANALYSIS: This protocol describes an international multicenter prospective cohort study, in which all patients of 18 years and older presenting within three weeks after injury with a radiographically diagnosed displaced proximal humerus fracture can be included. Based on patient characteristics and radiographic images several clinical experts advise on the preferred treatment option. In case of disagreement among the experts, the patient can be included in the study. The actual treatment that will be delivered is at the discretion of the treating physician. The primary outcome is the QuickDash score at 12 months. Propensity score matching will be used to control for potential confounding of the relation between treatment modality and QuickDash scores. DISCUSSION: The LADON study is an international multicenter prospective cohort study with a relatively new methodological study design. This study is a "natural experiment" meaning patients receive standard local treatment and surgeons perform standard local procedures, therefore high participation rates of patients and surgeons are expected. Patients are only included after expert panel evaluation, when there is proven disagreement between experts, which makes this a unique study design. Through this inclusion process, we create two comparable groups whom received different treatments and where expert disagree about the already initiated treatment. Since we are zooming in on this particular patient group, confounding will be largely mitigated. Internationally the treatment of proximal humerus fractures are still much debated and differs much per country and hospital. This observational study with a natural experiment design will create insight into which treatment modality is to be preferred for patients in whom there is disagreement about the optimal treatment strategy. TRIAL REGISTRATION: Registered in Netherlands trial register NL9357 and Swiss trial register CH 2020-00961; https://clinicaltrials.gov/.

Concept for Minimally Invasive Hook Plate Stabilisation of the Acromioclavicular Joint.

AIMS: Despite the availability of various operative procedures, hook plates are still one of the main implants used for the treatment of acromioclavicular (AC) joint dislocation. The aim of this report is to present a novel minimally invasive operation technique for AC hook plate fixation. The functional outcomes of patients operated upon with this technique are presented. PATIENTS AND METHODS: A retrospective analysis was performed for 5 patients who were operated upon with minimally invasive hook plate fixation. The QuickDASH score (QDS) and subjective shoulder value (SSV) were used to express functional outcomes, and the numeric rating scale (NRS) was used to evaluate pain. RESULTS: The mean (SD) follow-up was 30±7 months. Patients were hospitalized for a mean of 3±1 days and operated upon for a mean of 54±7 minutes. Functional outcomes measured with the QDS showed a median (IQR) of 2.3 (0 - 6.8) and a median SSV relative to the healthy side of 95% (89 - 100). The median NRS was 0 (0 - 0). CONCLUSION: Minimally invasive hook plate fixation for acromioclavicular joint dislocation led to excellent functional outcome scores without complications in a small case series of 5 patients.