bluuebunny/crossref_metadata_2025 huggingface dataset:
INCREASING LOCAL CELL DENSITY BY SOUND TO ENGINEER VASCULARIZED BONE CONSTRUCTS
Authors: Guex A.G. , Krattiger L.A. , Carrara B.M. , Alini M. , Ehrbar M. , Serra T.
Published: July 2023

Successful application of patient derived cells to engineer vascularized bone grafts is often hampered by low cell numbers and lengthy in vitro expansion. With sound induced morphogenesis (SIM), local cell density enhancement was shown to improve microvasculature formation at lower cell concentration than conventional methods [1]. SIM takes advantage of hydrodynamic forces that act on cells to arrange them within a hydrogel. Following, we are evaluating the potential of cell-hydrogel biografts with high local cell density to improve the therapeutic efficacy in clinical scenarios such as anastomosis or bone formation within non-union fractures.

To assess anastomosis, human umbilical vein endothelial cells (HUVEC) and human mesenchymal stromal cells (MSC) were mixed at a 1:1 ratio in PEG-based or Dextran-based hydrogels at a final concentration of 2×106 cells×mL-1. For ectopic bone formation, MSC were resuspended in PEG-based hydrogels at 2×106 or 5×106 cells×mL-1, with or without BMP-2. Cells were assembled into distinct patterns at a frequency of 60 Hz. Four biografts of 4 × 9 mm2 were implanted at the back of nude mice (total of 7 animals) and harvested after 2 or 8 weeks. Explants were fixed and imaged as whole constructs or embedded in paraffin for histological analysis.

Upon explantation, microscopic evaluation indicated that HUVEC were retained within the PEG-hydrogel after 2 weeks and formed a pre-vascular network. In the second study, ectopic bone formation was more pronounced in areas of higher local cell density based on visual inspection. Ongoing experiments are further characterizing bone formation by micro-CT and histological evaluation.

Our results indicate that local cell density enhancement by sound requires a lower initial cell concentration than conventional, static seeding methods to achieve comparable microvasculature structures or local osteogenesis.
USING A REGISTRY TO DRIVE OUTCOMES: A REDUCTION IN OPIOID PRESCRIPTION SIZE AFTER TOTAL JOINT ARTHROPLASTY CAN BE SAFELY PERFORMED WITHOUT AN INCREASE IN COMPLICATIONS
Authors: Wenzlick T. , Kutzner A. , Markel D. , Hughes R. , Chubb H. , Roberts K.
Published: July 2023

Excessive opioid prescriptions after total joint arthroplasty (TJA) increase risks for adverse opioid related events, chronic opioid use, and increase the availability of opioids for unlawful diversion. Thus, decreasing postoperative prescriptions may improve quality after TJA. Concerns exist that a decrease in opioids prescribed may increase complications such as readmissions, emergency department (ED) visits or worsened patient reported outcomes (PROs). The purpose of this quality improvement study was to explore whether a reduction in opioids prescribed after TJA resulted in increased complications.

Methods: Data originated from a statewide arthroplasty database (MARCQI). The database collects over 96% of all TJA performed in the state of Michigan, USA. Data was prospectively abstracted and included OMEs prescribed at discharge, readmissions, ED visits within 30 days and PROs. Data was collected one year before and after the creation of an opioid prescribing protocol that had decreased prescriptions by approximately 50% in opioid naive and tolerant patients. Trends were monitored using Shewhart control charts.

84,998 TJA over two-years were included. All groups showed a reduction in opioids prescribed. Importantly, no increased complications occurred concomitant to this reduction. No increases in ED visits or readmissions, and no decreases in KOOSJR/HOOSJR/PROMIS10 scores were noted in any of the groups.

Using large data sets and registries can drive performance and improve quality. The MARCQI Postoperative opioid prescription recommendations and performance measures decreased total oral morphine equivalents prescribed over a large and diverse population by approximately 50% without decreasing PROs or increasing ED visits or hospital readmissions. A reduction in opioids prescribed after TJA can be accomplished safely and without an increase in complications across a large population.
LOW-PROFILE DUAL MINI-FRAGMENT PLATING OF DIAPHYSEAL CLAVICLE FRACTURES: A BIOMECHANICAL STUDY
Authors: Pastor T. , Knobe M. , Ciric D. , Zderic I. , van de Wall B. , Rompen I. , Visscher L. , Link B-C. , Babst R. , Richards G. , Gueorguiev B. , Beeres F.
Published: July 2023

Implant removal after clavicle plating is common. Low-profile dual mini-fragment plate constructs are considered safe for fixation of diaphyseal clavicle fractures. The aim of this study was to investigate: (1) the biomechanical competence of different dual plate designs from stiffness and cycles to failure, and (2) to compare them against 3.5mm single superoanterior plating.

Twelve artificial clavicles were assigned to 2 groups and instrumented with titanium matrix mandible plates as follows: group 1 (G1) (2.5mm anterior+2.0mm superior) and group 2 (G2) (2.0mm anterior+2.0mm superior). An unstable clavicle shaft fracture (AO/OTA15.2C) was simulated. Specimens were cyclically tested to failure under craniocaudal cantilever bending, superimposed with torsion around the shaft axis and compared to previous published data of 6 locked superoanterior plates tested under the same conditions (G3).

Displacement (mm) after 5000 cycles was highest in G3 (10.7±0.8) followed by G2 (8.5±1.0) and G1 (7.5±1.0), respectively. Both outcomes were significantly higher in G3 as compared to both G1 and G2 (p≤0.027). Cycles to failure were highest in G3 (19536±3586) followed by G1 (15834±3492) and G2 (11104±3177), being significantly higher in G3 compared to G2 (p=0.004). Failure was breakage of one or two plates at the level of the osteotomy in all specimens. One G1 specimen demonstrated failure of the anterior plate. Both plates in other G1 specimens. Majority of G2 had fractures in both plates. No screw pullout or additional clavicle fractures were observed among specimens.

Low-profile 2.0/2.0 dual plates demonstrated similar initial stiffness compared to 3.5mm single plates, however, had significantly lower failure endurance. Low-profile 2.5/2.0 dual plates showed significant higher initial stiffness and similar resistance to failure compared to 3.5mm single locked plates and can be considered as a useful alternative for diaphyseal clavicle fracture fixation. These results complement the promising results of several clinical studies.
INVESTIGATION OF CELL AGGREGATE SIZE AND POTENTIAL BONE GROWTH WITH BONE CELL LINE AND HUMAN MESENCHYMAL STEM CELLS
Authors: Deegan A. , Lawlor L. , Yang X. , Yang Y.
Published: July 2023

Our previous research has demonstrated that minor adjustments to in vitro cellular aggregation parameters, i.e. alterations to aggregate size, can influence temporal and spatial mineral depositions within maturing bone cell nodules. What remains unclear, however, is how aggregate size might affect mineralisation within said nodules over long-term in vivo culture.

In this study, we used an osteoblast cell line, MLO-A5, and a primary cell culture, mesenchymal stem cells (MSC), to compare small (approximately 80 µm) with large (approximately 220 µm) cellular aggregates for potential bone nodule development after 8 weeks of culturing in a mouse model (n = 4 each group). In total, 30 chambers were implanted into the intra-peritoneal cavity of 20 male, immunocompromised mice (MF1-Nu/Nu, 4 – 5 weeks old). Nine small or three large aggregates were used per chamber. Neoveil mesh was seeded directly with 2 × 103 cells for monolayer control. At 8 weeks, the animals were euthanised and chambers fixed with formalin. Aggregate integrity and extracellular material growth were assessed via light microscopy and the potential mineralisation was assessed via micro-CT.

Many large aggregates appeared to disintegrate, whilst the small aggregates maintained their form and produced additional extracellular material with increased sizes. Both MLO-A5 cells and MSC cells saw similar results. Interestingly, however, the MSCs were also seen to produce a significantly higher volume of dense material compared to the MLO-A5 cells from micro-CT analysis.

Overall, a critical cell aggregate size appeared to exist balancing optimal tissue growth with oxygen diffusion, and cell source may influence differentiation pathway despite similar experimental parameters. The MSCs, for example, were likely producing bone via the endochondral ossification pathway, whilst the matured bone cells, MLO-A5 cells, were likely producing bone via the intramembranous ossification pathway.
NOVEL DYNAMIC STABILIZATION SYSTEM PROVIDES BETTER AP TRANSLATION AND AXIAL TIBIOFIBULAR JOINT STABILITY
Authors: Souleiman F. , Zderic I. , Pastor T. , Gehweiler D. , Gueorguiev B. , Galie J. , Kent T. , Tomlinson M. , Schepers T. , Swords M.
Published: July 2023

The quest for optimal treatment of acute distal tibiofibular syndesmotic disruptions is still in progress. Using suture-button repair devices is one of the dynamic stabilization options, however, they may not be always appropriate for stabilization of length-unstable syndesmotic injuries. Recently, a novel screw-suture repair system was developed to address such issues. The aim of this study was to investigate the performance of the novel screw-suture repair system in comparison to a suture-button stabilization of unstable syndesmotic injuries.

Eight pairs of human cadaveric lower legs were CT scanned under 700 N single-leg axial loading in five foot positions – neutral, 15° external/internal rotation and 20° dorsi-/plantarflexion – in 3 different states: (1) pre-injured (intact); (2) injured, characterized by complete syndesmosis and deltoid ligaments cuts simulating pronation-eversion injury types III and IV as well as supination-eversion injury type IV according to Lauge-Hansen; (3) reconstructed, using a screw-suture (FIBULINK, Group 1) or a suture-button (TightRope, Group 2) implants for syndesmotic stabilization, placed 20 mm proximal to the tibia plafond. Following, all specimens were: (1) biomechanically tested over 5000 cycles under combined 1400 N axial and ±15° torsional loading; (2) rescanned. Clear space (diastasis), anterior tibiofibular distance, talar dome angle and fibular shortening were measured radiologically from CT scans. Anteroposterior (AP), axial, mediolateral and torsional movements at the distal tibiofibular joint level were evaluated biomechanically via motion tracking.

In each group clear space increased significantly after injury (p ≤ 0.004) and became significantly smaller in reconstructed compared with both pre-injured and injured states (p ≤ 0.041). In addition, after reconstruction it was significantly smaller in Group 1 compared to Group 2 (p < 0.001). AP and axial movements were significantly smaller in Group 1 compared with Group 2 (p < 0.001). No further significant differences were identified/detected between the groups (p ≥ 0.113).

Although both implant systems demonstrate ability for stabilization of unstable syndesmotic injuries, the screw-suture reconstruction provides better anteroposterior translation and axial stability of the tibiofibular joint and maintains it over time under dynamic loading. Therefore, it could be considered as a valid option for treatment of syndesmotic disruptions.
IRISIN STIMULATES ANABOLISM AND MATRIX SYNTHESIS IN HUMAN NUCLEUS PULPOSUS CELLS IN VITRO: NEW INSIGHTS INTO A CROSS-TALK BETWEEN THE MUSCLE AND THE INTERVERTEBRAL DISC
Authors: Vadalà G. , Di Giacomo G. , Ambrosio L. , Cicione C. , Tilotta V. , Russo F. , Papalia R. , Denaro V.
Published: July 2023

This study aimed to investigate the effect of irisin on human nucleus pulposus cells (hNPCs) in vitro. Our hypothesis was that irisin would improve hNPC metabolism and proliferation.

hNPCs were isolated from intervertebral discs and cultured in alginate beads. hNPCs were exposed to phosphate-buffered saline (PBS) or recombinant irisin (r-irisin) at 5, 10 and 25 ng/mL (n=4). Each experiment was performed in triplicate. Cell proliferation was assessed with trypan blue staining-automated cell counting and PicoGreen assay. Glycosaminoglycan (GAG) content was measured using the DMMB assay. Metabolic activity was assessed with the MTT assay and the Griess Reagent System. Gene expression of collagen type II (COL2), matrix metalloproteinase (MMP)-13, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and −3, aggrecan, interleukin (IL)-1β, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-5 was measured by RT-PCR. MTT assay and ADAMTS-5, COL2, TIMP-1 and IL-1β gene expression were evaluated following incubation with 5, 10 and 25 ng/mL r-irisin for 24 hours and subsequent culture with 10 ng/ml IL-1β and vice versa (incubation for 24 hours with IL-1β and subsequent culture with r-irisin).

Irisin increased hNPC proliferation (p<0.001), metabolic activity (p<0.05), GAG content (p<0.01), as well as COL2 (p<0.01), aggrecan (p<0.05), TIMP-1 and −3 (p<0.01) gene expression, while decreasing MMP-13 (p<0.05) and IL-1β (p<0.001) mRNA levels. r-irisin pretreatment of hNPCs cultured in pro-inflammatory conditions resulted in a rescue of metabolic activity (p<0.001) and a decrease of IL-1β (p<0.05) levels. Similarly, incubation of hNPCs with IL-1β and subsequent exposure to r-irisin increased hNPC metabolic activity (p<0.001), COL2 gene expression (p<0.05) and decreased IL-1β (p<0.05) and ADAMTS-5 levels (p<0.01).

Irisin stimulates hNPC proliferation, metabolic activity, and anabolism by reducing IL-1β and catabolic enzyme expression while promoting matrix synthesis.
A NEW METHOD FOR IMPROVED MECHANICAL AND BIOLOGICAL FIXATION OF FRACTURE FIXATION DEVICES
Authors: Raina D.B. , Markeviciute V. , Arvidsson L. , Törnquist E. , Stravinskas M. , Kok J. , Jacobson I. , Liu Y. , Tengattini A. , Sezgin E.A. , Vater C. , Zwingenberger S. , Isaksson H. , Tägil M. , Tarasevicius S. , Lidgren L.
Published: July 2023

Majority of osteoporosis related fractures are treated surgically using metallic fixation devices. Anchorage of fixation devices is sometimes challenging due to poor osteoporotic bone quality that can lead to failure of the fracture fixation.

Using a rat osteoporosis model, we employed neutron tomography and histology to study the biological effects of implant augmentation using an isothermally setting calcium sulphate/hydroxyapatite (CaS/HA) biomaterial with synthetic HA particles as recruiting moiety for systemically administered bisphosphonates. Using an osteoporotic sawbones model, we then provide a standardized method for the delivery of the CaS/HA biomaterial at the bone-implant interface for improved mechanical anchorage of a lag-screw commonly used for hip fracture fixation. As a proof-of-concept, the method was then verified in donated femoral heads and in patients with osteoporosis undergoing hip fracture fixation.

We show that placing HA particles around a stainless-steel screw in-vivo, systemically administered bisphosphonates could be targeted towards the implant, yielding significantly higher peri-implant bone formation compared to un-augmented controls. In the sawbones model, CaS/HA based lag-screw augmentation led to significant increase (up to 4 times) in peak extraction force with CaS/HA performing at par with PMMA. Micro-CT imaging of the CaS/HA augmented lag-screws in cadaver femoral heads verified that the entire length of the lag-screw threads and the surrounding bone was covered with the CaS/HA material. X-ray images from fracture fixation surgery indicated that the CaS/HA material could be applied at the lag-screw-bone interface without exerting any additional pressure or risk of venous vascular leakage.: We present a new method for augmentation of lag-screws in fragile bone. It is envisaged that this methodcould potentially reduce the risk of fracture fixation failure especially when HA seeking “bone active” drugs are used systemically.
DUAL APPLICATION OF BACTERIOPHAGES AND MEROPENEM USING MICROBEAD-LOADED HYDROGEL FOR TREATMENT OF MULTIDRUG-RESISTANT PSEUDOMONAS AERUGINOSA IN A MOUSE MODEL OF BONE INFECTION
Authors: Chitto M. , Chen B. , Kunisch F. , Wychowaniec J. , Onsea J. , Post V. , Richards G. , Zeiter S. , Wagemans J. , Trampuz A. , D'Este M. , Moreno M. , Lavigne R. , Moriarty F.
Published: July 2023

Fracture related infection remains a major challenge in musculoskeletal trauma surgery. Despite best practice, treatment strategies suffer from high failure rates due to antibiotic resistance and tolerance. Bacteriophages represent a promising alternative as they retain activity against such bacteria. However, optimal phage administration protocols remain unknown, although injectable hydrogels, loaded with phage and conventional antibiotics, may support conventional therapy.

In this study we tested the activity of meropenem, and two newly isolated bacteriophages (ϕ9 and ϕ3) embedded within alginate-chitosan microbeads and a hydrogel. Antibiotic and phage stability and activity were monitored in vitro, over a period of 10 days. In vivo, the same material was tested in treatment of a 5-day old Pseudomonas aeruginosa infection of a tibial plate osteotomy in mice. Treatment involved debridement and 5 days of systemic antibiotic therapy plus: i- saline, ii-phages in saline, iii-phages and antibiotics loaded into a hydrogel (n=7 mice/group). To assess the efficacy of the treatments, the infection load was monitored during revision surgery with debridement of the infected tissue after 5,10 and 13 days (euthanasia) by CFU and PFU quantification.

In vitro testing confirmed that the stability of meropenem and activity of ϕ9 and ϕ3, was not affected within the alginate beads or hydrogel over 10 days. The in vivo study showed that all mice receiving phages and antibiotics loaded into a hydrogel survived the infection with a reduction of the bacterial load in the soft tissue. Active phages could be recovered from the infected site at euthanasia (104 PFU/g).

The hydrogel loaded with bacteriophages and meropenem showed a positive result in locally reducing the infection load indicating a synergistic effect of the selected antimicrobials. Overall, our new strategy shows encouraging results for improving the treatment of antibiotic-resistant biofilm infections that are related to medical implants.
PRE-CLINICAL TESTING AND FINITE ELEMENT SIMULATIONS OF ORTHOPAEDIC IMPACTION INSTRUMENTS USED IN SEATING OF IMPLANTS
Authors: Preutenborbeck M. , Wright P. , Loughran G. , Bishop N.
Published: July 2023

Orthopaedic impaction-instruments are used to drive implants into the bone of the patient. Pre-clinical experimental testing protocols and computer models of those are used to assess robustness and functional efficiency of such instruments. This generally involves impaction of the instrument mounted on a substrate that should represent the mechanics of the patient. In this study, the effects of the substrate on stressing of the impaction-instruments were investigated using dynamic finite element analysis. Model results were compared with experimental data from lab protocols, which have been derived to recreate the mechanics of cadaveric implantations, which represent clinical conditions.

FEA models of selected experimental protocols were created in which a simplified instrument was impacted on substrates with varying material properties and boundary conditions. After impaction, the instrument settled into a modal vibration which then decayed over time. The resulting axial strain data from the computational model was compared to strain-gauge data collected from experimental measurements. Strain signal amplitude, frequency and decay were compared. The damping-ratio was derived from the decay of the strain signal.

The computational model slightly over-predicted the initial experimental strain amplitudes in all cases, but the frequency of the cyclic strain signals matched. However, the model underestimated the experimentally measured rate of signal decay. Inclusion of implant seating and soft-tissue conditions had little effect on decay.

Clinical failures of impaction-instruments may be related to multiple fatigue cycles for each impaction and should be modelled accurately to allow failure prediction. Any soft substrate results in an impedance mismatch at the instrument interface, which reflects the pressure wave and causes vibration with a frequency related to the speed-of-sound in the instrument, and its geometry. While this could be accurately modelled computationally, signal decay was underestimated. Further experimental quantification of energy losses will be important to understand vibration decay.
CELLULAR RESPONSE OF HEALTHY AND OSTEOPOROTIC BONE CELLS TOWARDS TITANIUM SCAFFOLDS CREATED BY NOVEL LASER TEXTURING COMPARED WITH CLINICAL STANDARD SLA IMPLANTS
Authors: Stich T. , Kovářík T. , Křenek T. , Alt V. , Docheva D.
Published: July 2023

The goal was to analyze the cellular response, specifically the osteogenic capacity, of titanium (Ti) implants harbouring a novel laserbased-surface-structure with the overall aim: augmented osteointegration. Surface micro-/nanoproperties greatly influence cell behaviour at the tissue-implant-interface and subsequent osteointegration. We investigated Ti-materials subjected to a specially developed shifted-Laser-Surface-Texturing (sLST) technology and compared them to a standard roughening-technique (sand-blasting-acid-etching, SLA). The biological response was evaluated with hMSCs, which are naturally available at the bone-implant-interface. We hypothesized: the novel surface is beneficial for our three different (young/healthy-YH; aged/healthy-AH;aged/osteoporotic-OP) cohorts.

The sLST was performed using a SPI-G3-series laser (beam-wavelength=1064nm, pulse-duration=200ns). For the SLA surface, Ti was sandblasted, afterwards acid-etched (HCl/H2SO4). Three different hMSC cohorts were studied: YH: n=6,29±6; AH: n=5,79±5; OP: n=5,76±5 years (osteoporosis confirmed via DEXA-scan). OP hMSCs show e.g. ColI-deficient-matrix and decreased mineralization. Cells were examined for survival, cell proliferation and cytoskeleton arrangement. Osteogenic differentiation was carried out over 21 days, matrix mineralization was validated with Alizarin-Red-S-staining and quantification.

Laser-texturing generated precisely the desired microgeometry. On nanostructural level, differently-sized Ti-droplets were formed stochastically by laser-induced-Ti-plasma. Live/dead-/Actin-stainings showed comparable results for all cohorts and surfaces in terms of survival and cell shape. On Ti-materials, cell growth showed no significant difference between the 3 cohorts. Alizarin quantification revealed the highest levels on laser-textured-surfaces; highest value for YH, followed by AH, lastly OP; no significance between AH/YH, but between OP/YH (p<0.0001). However, mineralization of all cohorts cultured on laser-textured-surfaces increased significantly (p<0.0001) compared to respective SLA-group, with >20fold higher value in the OP-cohort (AH:11fold, YH:6fold).

The data proves the biocompatibility of the laser-structured-Ti for young+aged cohorts. Osteogenic differentiation was significantly augmented on laser-treated-Ti. Most intriguingly, OP-donors could reach manifold increased mineralization, suggesting the novel laser texturing can counteract the osteoporotic phenotype. As osteogenesis-enhancing capacities may be related to mechanisms controlling cellular shape/fate, further investigations referring to this are currently ongoing. In conclusion, our laser-textured-Ti-materials are safe, can have a demand-oriented designer-surface-topography and represent a great potential for development into next-generation-implants suitable for different patient-cohorts, especially osteoporosis patients.
INTERVERTEBRAL DISC CELLS IN VIVO INTERNALIZE GRAM-POSITIVE BACTERIA: IMPLICATIONS FOR INTERVERTEBRAL DISC DEGENERATION
Authors: Nüesch A. , Kanelis E. , Alexopoulos L. , Williams F. , Geris L. , Gantenbein B. , Lacey M. , Le Maitre C.
Published: July 2023

A key cause of low back pain is the degeneration of the intervertebral disc (IVD). Causality between infection of the IVD and its degenerative process gained great interest over the last decade. Granville Smith et al. (2021) identified 36 articles from 34 research studies investigating bacteria in human IVDs. Bacteria was identified in 27 studies, whereas 9 attributed bacterial presence to contamination. Cutibacterium acnes was the most abundant, followed by coagulase-negative staphylococcus. However, whether bacteria identified were present in vivo or represent perioperative contamination remains unclear. This study investigated whether bacteria are present in IVDs and what potential effects they may have on native disc cells.

Immunohistochemical staining for Gram positive bacteria was performed on human IVD tissue to identify presence and characterise bacterial species. Nucleus pulposus (NP) cells in monolayer and 3D alginate were stimulated with LPS and Peptidoglycan (0.1-50 µg/ml) for 48hrs. Following stimulation qPCR for factors associated with disc degeneration including matrix genes, matrix degrading enzymes, cytokines, neurotrophic factors and angiogenic factors and conditioned media collected for ELISA and luminex analysis

Gram positive bacteria was detected within human IVD tissue. Internalisation of bacteria by NP cells influenced the cell and nuclei morphology. Preliminary results of exposure of NP cells to bacterial components indicate that LPS as well as Peptidoglycan increase IL-8 and ADAMTS-4 gene expression following 48 hours of stimulation with a dose response seen for IL-8 induction by peptidoglycan compared to the control group. Underlining these results, IL-8 protein release was increased for treated groups compared to non-treated control. Further analysis is underway investigating other output measures and additional biological repeats.

This study has demonstrated bacteria are present within IVD cells within IVD tissue removed from degenerate IVD and is determining the potential influence of these on disc degeneration.
ACTIVATION OF THE MECHANOSENSITIVE ION CHANNEL PIEZO1 UPREGULATES THE PROINFLAMMATORY CYTOKINE IL6 IN OSTEOCYTES DERIVED FROM HUMAN Y201 STEM CELLS
Authors: Gilbert S. , Jones R. , White P. , Mason D.
Published: July 2023

Stimulation of the mechanosensitive ion channel, Piezo1 promotes bone anabolism and SNPs in the Piezo1 locus are associated with changes in fracture risk. Osteocytes function as critical regulators of bone homeostasis by sensing mechanical signals. The current study used a human, cell-based physiological, 3D in vitro model of bone to determine whether loading of osteocytes in vitro results in upregulation of the Piezo1 pathway.

Human Y201 MSCs, embedded in type I collagen gels and differentiated to osteocytes for 7-days, were subjected to pathophysiological load (5000 µstrain, 10Hz, 5 mins; n=6) with unloaded cells as controls (n=4). RNA was extracted 1-hr post load and assessed by RNAseq analysis. To mimic mechanical load and activate Piezo1, cells were differentiated to osteocytes for 13 days and treated ± Yoda1 (5µM, 2- and 24-hs, n=4); vehicle treated cells served as controls (n=4). RNA was subjected to RT-qPCR and data normalised to the housekeeping gene, YWHAZ. Media was analysed for IL6 release by ELISA.

Mechanical load upregulated Piezo1 gene expression (16.5-fold, p<0.001) and expression of the transcription factor NFATc1, and matricellular protein CYR61, known regulators of Piezo1 mechanotransduction (3-fold; p= 5.0E-5 and 6.8-fold; p= 6.0E-5, respectively). After 2-hrs, Yoda1 increased the expression of the early mechanical response gene, cFOS (11-fold; p=0.021), mean Piezo1 expression (2.3-fold) and IL-6 expression (103-fold, p<0.001). Yoda1 increased the release of IL6 protein after 24 hours (7.5-fold, p=0.001).

This study confirms Piezo1 as an important mechanosensor in osteocytes. Piezo1 activation mediated an increase in IL6, a cytokine that drives inflammation and bone resorption providing a direct link between mechanical activation of Piezo1, bone remodeling and inflammation, which may contribute to mechanically induced joint degeneration in diseases such as osteoarthritis. Mechanistically, we hypothesize this may occur through promoting Ca2+ influx and activation of the NFATc1 signaling pathway.
OBJECTIVELY MEASURED KNEE INSTABILITY DURING PIVOT-SHIFT TEST: AN EXPERIMENTAL DYNAMIC RSA STUDY
Authors: Vind T.D. , Petersen E.T. , Lindgren L. , Sørensen O.G. , Stilling M.
Published: July 2023

The Pivot-shift test is a clinical test for knee instability for patinets with Anterior cruciate ligament (ACL), however the test has low inter-observer reliability. Dynamic radiostereometry (dRSA) imaging is a highly precise method for objective evaluation of joint kinematics. The purpose of the study was to quantify precise knee kinematics during Pivot-shift test by use of the non-invasive dynamic RSA imaging.

Eight human donor legs with hemipelvis were evaluated. Ligament lesion intervention of the ACL was performed during arthroscopy and anterolateral ligament (ALL) section was performed as a capsular incision. Pivot-shift test examination was recorded with dRSA on ligament intact knees, ACL-deficient knees and ACL+ALL-deficient knees.

A Pivot-shift pattern was identifyable after ligament lesion as a change in tibial posterior drawer velocity from 7.8 mm/s in ligament intact knees, to 30.4 mm/s after ACL lesion, to 35.1 mm/s after combined ACL-ALL lesion. The anterior-posterior drawer excursion increased from 2.8 mm in ligament intact knees, to 7.2 mm after ACL lesion, to 7.6 mm after combined lesion. Furthermore a change in tibial rotation was found, with increasing external rotation at the end of the pivot-shift motion going from intact to ACL+ALL-deficient knees

This experimental study demonstrates the feasibility of RSA to objectively quantify the kinematic instability patterns of the knee during the Pivot-shift test. The dynamic parameters found through RSA displayed the kinematic changes from ACL to combined ACL-ALL ligament lesion.
OSTEOCHONDRAL GLENOID LOSS: REMAINING GLENOID DEPTH AND CONCAVITY ARE STRONGER PREDICTIVE PARAMETERS FOR SHOULDER INSTABILITY THAN DEFECT SIZE
Authors: Souleiman F. , Zderic I. , Pastor T. , Varga P. , Gueorguiev B. , Richards G. , Osterhoff G. , Hepp P. , Theopold J.
Published: July 2023

Osteochondral glenoid loss is associated with recurrent shoulder instability. The critical threshold for surgical stabilization is multidimensional and conclusively unknown. The aim of this work was to provide a well- measurable surrogate parameter of an unstable shoulder joint for the frequent anterior-inferior dislocation direction.

The shoulder stability ratio (SSR) of 10 paired human cadaveric glenoids was determined in anterior-inferior dislocation direction. Osteochondral defects were simulated by gradually removing osteochondral structures in 5%-stages up to 20% of the intact diameter. The glenoid morphological parameters glenoid depth, concavity gradient, and defect radius were measured at each stage by means of optical motion tracking. Based on these parameters, the osteochondral stability ratio (OSSR) was calculated. Correlation analyses between SSR and all morphological parameters, as well as OSSR were performed.

The loss of SSR, concavity gradient, depth and OSSR with increasing defect size was significant (all p<0.001). The loss of SSR strongly correlated with the losses of concavity gradient (PCC = 0.918), of depth (PCC = 0.899), and of OSSR (PCC = 0.949). In contrast, the percentage loss based on intact diameter (defect size) correlated weaker with SSR (PCC=0.687). Small osteochondral defects (≤10%) led to significantly higher SSR decrease in small glenoids (diameter <25mm) compared to large (≥ 25mm) ones (p ≤ 0.009).

From a biomechanical perspective, the losses of concavity gradient, glenoid depth and OSSR correlate strong with the loss of SSR. Therefore, especially the loss of glenoidal depth may be considered as a valid and reliable alternative parameter to describe shoulder instability. Furthermore, smaller glenoids are more vulnerable to become unstable in case of small osteochondral loosening. On the other hand, the standardly used percentage defect size based on intact diameter correlates weaker with the magnitude of instability and may therefore not be a valid parameter for judgement of shoulder instability.
ANALYSIS OF TRAUMA AND ORTHOPAEDICS SPECIALIST TRAINEES’ EDUCATIONAL EXPERIENCE DURING THE COVID-19 PANDEMIC
Authors: Pervaiz A. , Nahas S. , Waterman J.
Published: July 2023

Since the emergence of the COVID-19 pandemic, the NHS has been under unprecedentedpressure. Elective surgery had ceased, and trauma surgery has decreased dramatically. Surgical training is multi-faceted and requires a specialist trainee to have a timetable which includes regular elective non-emergency operating, trauma operating and training in outpatient clinics. Consequently, training in theatre and the achievement of operative numbers and index procedures had not been possible for Trauma and Orthopaedic (T&O) specialist trainees.

The Joint Committee on Surgical Training (JCST) has clear training index requirements for all T&O specialist trainees. In this study, we surveyed specialist trainees in the North West London deanery against the annual requirements set by the JCST guidelines. In addition, we retrospectively assessed the total number of trauma referrals and operations scheduled in our unit during the COVID-19 outbreak compared to that one year previously. The aim of this study is to objectively assess the effect the pandemic has on T&O specialist training.

A total of 24 responses were collected from specialist trainees. The results of the survey showed 87% of trainees believed that their training had been affected. 75% of trainees felt they were not on track to meet operative numbers for the year, and 71% felt index number achievement had been affected. Trauma case numbers dropped by 20% compared to that one year previously.

We recommend timely, planned and conscientious remediation for specialist trainees’ educational requirements. Specialist trainees must take responsibility for their training and use of additional educational opportunities. Clinical supervisors and training programme directors must provide additional support and guidance to achieve ARCP outcomes however in some scenarios extension of training may be necessary.
NECK OF FEMUR FRACTURES AND THE INCIDENCE OF METASTASIS ON LONG LEG FEMUR VIEWS
Authors: O'Boyle M. , Fraser E. , Dickson S. , Mansbridge D.
Published: July 2023

Neck of femur fractures are a common trauma presentation and patients with a history of malignancy are sent for long leg femur views (LLF), to exclude a distal lesion which would alter the management plan (Intra-medullary nail/Long stem Hemiarthroplasty). The aim of this is to identify incidence of malignancy on LLF views, the length of time in between each xray (XR) and to identify demographics.

Data was retrospectively collected from 01/01/2021 to 31/01/2021 from a single centre. All patients admitted to the Queen Elizabeth University Hospital had their electronic records (Bluespier, PACS, Clinical Portal) accessed. These confirmed if patients had a past medical history of malignancy, if they had LLF view and the time differences between diagnostic pelvis XR and LLF XR.

A total of 784 patients were identified in the specified time period. Of these, 138 were identified with a malignancy and there were 85 LLF views completed. LLF views diagnosed 1 patient with known prostate cancer that had a new distal femoral metastasis (Incidence = 1.28 cases per 1000). This patient underwent further imaging (MRI Femur) and received a long stem hip hemiarthroplasty. The average length of wait between the images was 9 hours 27 minutes.

LLF views can alter management of patients with malignancy and are therefore useful to perform. There can be a long delay between each image. Therefore we recommend imaging tumour with common bony metastasis (Renal, Thyroid, Breast, Prostrate, Lung) and other remaining tumours with known secondary metastasis. Imaging primary low risk (eg basal cell carcinoma) can lead to long delays in a frail patient cohort and consideration should be given to rationalise appropriate use of resources.
‘SHOULD WE SEND THE HEAD?’ INCIDENCE OF PATHOLOGICAL NECK OF FEMUR FRACTURES: A ONE-YEAR RETROSPECTIVE OVERVIEW
Authors: Dickson S. , Fraser E. , O'Boyle M. , Mansbridge D.
Published: July 2023

Neck of femur fracture (NOF#) is the commonest reason for admission to an orthopaedic ward with 70-75,000 cases each year in the UK1. The femoral head is often sent to pathology if there is clinical suspicion of a malignant cause. There is limited evidence in the literature to support the efficacy of this2. The purpose of this project was to study the incidence of femoral head pathology analysis in NOF # patients with a background of malignancy and evaluate the impact this investigation has on guiding future management.

Retrospective analysis of all neck of femur fractures admitted to the Queen Elizabeth University Hospital between 01/01/2021 and 31/12/2021. The electronic notes were accessed and for patients with past medical history of malignancy, it was confirmed whether femoral head or bone reamings were sent to pathology, resultant findings and the impact on subsequent management.

In 2021, 784 patients were admitted to the QEUH with a NOF#. Of these, 770 (98.2%) underwent operative management, 138 (17.3%) of whom had a past medical history (PMH) of malignancy. Intra-operative pathology was sent from 19 (13.7%) of these 138 patients. No malignant cells were found in 13 (69%) samples, and in 6 (31%), the known active malignancy was confirmed. In all cases where samples were sent for pathology, none caused any change in management.

In this retrospective study, pathological investigations in NOF# patients with a PMH of malignancy had no impact on further management. The authors would not advocate for sending pathology results in this cohort group.
IMPACT OF THE COVID-19 PANDEMIC IN THE MANAGEMENT OF PATIENTS WITH FEMORAL NECK FRACTURE IN THE EMERGENCY ROOM: THE EXPERIENCE IN OUR HOSPITAL
Authors: Domingues I. , Cunha R. , Domingues L. , Silva E. , Carvalho S. , Lavareda G. , Carvalho R.
Published: July 2023

The covid-19 pandemic had a great impact in the daily clinical and surgical practice. Concerning patients with a femoral neck fracture, there is the need of a negative Sars-CoV-2 test or an established isolation period for the positive cases, pre-operatively. The goal of this study was to evaluate the impact of the pandemic in the management of patients with femoral neck fractures, who were submitted to surgical treatment with hemiarthroplasty, in our hospital.

A retrospective, observational study was performed, analysing the patients with femoral neck fractures submitted to hip hemiarthroplasty, during the years 2019 (before the pandemic) and 2020 (first year of the pandemic). We analysed the first 5 patients operated in each month of the mentioned years.

We analysed 56 and 60 patients submitted to surgery in the years 2019 and 2020, respectively. The inpatient days were, in average, 14.1 and 13.1. Patients were operated, in average, 3.0 and 3.8 days after admission (corrected to 2.5 and 3.6 days if the time of discontinuation of anticoagulants or antiplatelets needed before surgery is deducted). There were peri-operative complications in 53.6% and 46.7% of the patients, in 2019 and 2020 respectively. The most common complication in both groups was a low postoperative haemoglobin level needing red blood cell transfusion. One-year postoperative mortality rate was 17.9% and 13.3%, respectively.

Despite the changes triggered by the new pandemic, there was an overall maintenance of the quality of the management of these patients, with only a slight increase in the interval between admission and surgery. Some of the remaining variables even showed an improvement when comparing the two groups of patients. Nevertheless, it is important to mention that there were patients infected with Covid-19 who died before being submitted to surgery, therefore not being present in these statistics.
THE VERTEBRAL BONE MARROW CLOT AS NEW AND ADVANCED AUTOLOGOUS CELL THERAPY IN SPINAL SURGICAL PROCEDURES
Authors: Salamanna F. , Brodano G.B. , Griffoni C. , Gasbarrini A. , Fini M. , Leggi L.
Published: July 2023

Due to the presence of megakaryocytes, platelets and clotting factors, bone marrow aspirate (BMA) tends to coagulate. For the first time, starting from our previous studies on mesenchymal vertebral stem cells, it has been hypothesized that coagulated BMA represents a safe and effective autologous biological scaffold for bone regeneration in spinal surgery. The present research involved advanced preclinical in vitro models and the execution of a pilot clinical study.

Evaluation of cell morphology, growth kinetics, immunophenotyping, clonogenicity, trilineage-differentiation, growth-factors and HOX and TALE gene expression were analyzed on clotted- and un-clotted human V-BMA. In parallel, a pilot clinical study on ten patients with degenerative spine diseases submitted to instrumented posterior arthrodesis, is ongoing to assess the ability of clotted-V-BMA to improve spinal fusion at 6- and 12-months follow-up.

Results demonstrated that clotted-V-BMA have significantly higher growth-factor expression and mesenchymal stem cell (MSCs) viability, homogeneity, clonogenicity, and ability to differentiate towards the osteogenic phenotype than un-clotted-V-BMA. Clotted-V-BMA also highlighted significant reduced expression of PBX1 and of MEIS3 genes negatively involved in osteoblast maturation and differentiation. From December 2020, eight patients have already been enrolled with first promising results that will be finally evaluated in the next two months.

The application of V-BMA-clot as carrier of progenitors and cytokines and as natural scaffold with a structural texture represents a point-of-care orthobiologic product to improve spinal fusion. Clinical application seems to be efficacy, and we will confirm and strengthen these data with the final results of the pilot clinical study.
MACHINE LEARNING PREDICTION AND OPTIMIZATION IMPROVES ELECTIVE ORTHOPAEDIC SURGERY SCHEDULING
Authors: Mosseri J. , Lex J. , Abbas A. , Toor J. , Ravi B. , Whyne C. , Khalil E.
Published: July 2023

Total knee and hip arthroplasty (TKA and THA) are the most commonly performed surgical procedures, the costs of which constitute a significant healthcare burden. Improving access to care for THA/TKA requires better efficiency. It is hypothesized that this may be possible through a two-stage approach that utilizes prediction of surgical time to enable optimization of operating room (OR) schedules.

Data from 499,432 elective unilateral arthroplasty procedures, including 302,490 TKAs, and 196,942 THAs, performed from 2014-2019 was extracted from the American College of Surgeons (ACS) National Surgical and Quality Improvement (NSQIP) database. A deep multilayer perceptron model was trained to predict duration of surgery (DOS) based on pre-operative clinical and biochemical patient factors. A two-stage approach, utilizing predicted DOS from a held out “test” dataset, was utilized to inform the daily OR schedule. The objective function of the optimization was the total OR utilization, with a penalty for overtime. The scheduling problem and constraints were simulated based on a high-volume elective arthroplasty centre in Canada. This approach was compared to current patient scheduling based on mean procedure DOS. Approaches were compared by performing 1000 simulated OR schedules.

The predict then optimize approach achieved an 18% increase in OR utilization over the mean regressor. The two-stage approach reduced overtime by 25-minutes per OR day, however it created a 7-minute increase in underutilization. Better objective value was seen in 85.1% of the simulations.

With deep learning prediction and mathematical optimization of patient scheduling it is possible to improve overall OR utilization compared to typical scheduling practices. Maximizing utilization of existing healthcare resources can, in limited resource environments, improve patient's access to arthritis care by increasing patient throughput, reducing surgical wait times and in the immediate future, help clear the backlog associated with the COVID-19 pandemic.
GSTT1 PROMOTES OSTEOGENIC DIFFERENTIATION OF ADIPOSE STEM CELLS
Authors: Lee E. , Ko J-Y. , Park S-Y. , Moon J-Y. , Im G.
Published: July 2023

We found that adipose stem cells are poorly differentiated into bone and that their ability to differentiate into bone varies from cell line to cell line. The osteogenic differentiation ability of the adipose stem cell lines was distinguished through Alzarin Red Staining, and the cell lines that performed well and those that did not were subjected to RNA-seq analysis. The selected gene GSTT1 (glutathione S-transferase theta-1) gene is a member of a protein superfamily that catalyzes the conjugation of reduced glutathione to a variety of hydrophilic and hydrophobic compounds. The purpose of this study is to treat avascular necrosis and bone defect by improving bone regeneration with adipose stem cells introduced with a new GSTT1 gene related to osteogenic differentiation of adipose stem cells. In addition, the GSTT1 gene has the potential as a genetic marker that can select a specific cell line in the development of an adipose stem cell bone regeneration drug.

Total RNA was extracted from each sample using the TRIzol reagent. Its concentration and purity were determined based on A260 and A260/A280, respectively, using a spectrophotometer. RNA sequencing library of each sample was prepared using a TruSeq RNA Library Prep Kit. RNA-seq experiments were performed for hADSCs. Cells were transfected with either GSTT1 at 100 nM or siControl (scramble control) by electroporation using a 1050 pulse voltage for 30 ms with 2 pulses using a 10 μl pipette tip.

The purpose of this study is to discover genetic markers that can promote osteogenic differentiation of adipose stem cells (hADSCs) through mRNA-seq gene analysis. The selected GSTT1 gene was found to be associated with the enhancement of osteogenic differentiation of adipose stem cells. siRNA against GSTT1 reduced osteogenic differentiation of hADSCs, whereas GSTT1 overexpression enhanced osteogenic differentiation of hADSCs under osteogenic conditions.

In this study, GSTT1 transgenic adipose stem cells could be used in regenerative medicine to improve bone differentiation. In addition, the GSTT1 gene has important significance as a marker for selecting adipose stem cells with potential for bone differentiation in the development of a therapeutic agent for bone regeneration cells.