Conventional Fixation Research Articles

Construction of Fe(III) Active Sites on Phenanthroline-Grafted g-C3N4: Reduced Work Function and Enhanced Intramolecular Charge Transfer for Efficient N2 Photofixation.

Photocatalytic nitrogen fixation is one of the important pathways for green and sustainable ammonia synthesis, but the extremely high bonding energy of the N≡N triple bond makes it difficult for conventional nitrogen fixation photocatalysts to directly activate and hydrogenate. Given this, we covalently grafted the phenanthroline unit onto graphitic carbon nitride nanosheets (CN) by the simple thermal oxidation method and complexed it with transition metal Fe3+ ions to obtain stable dispersed Fe active sites, which can significantly improve the photocatalytic activity. The Fe(III)-4-P-CN photocatalyst morphology consists of porous lamellar structures internally connected by nanowires. The special morphology of the catalysts gives them excellent nitrogen fixation performance, with an average NH3 yield of 492.9 μmol g-1 h-1, which is 6.5 times higher than that of the pristine CN, as well as better photocatalytic cycling stability. Comprehensive experiments and density-functional theory results show that Fe(III)-4-P-CN is more favorable than pristine CN for *N2 activation, effectively lowering the reaction energy barrier. Moreover, other byproducts (such as nitrate and H2O2) are also produced during the photocatalytic nitrogen fixation process, which also provides a new way for nitrogen-fixing photocatalysts to achieve multifunctional applications.

In situ Scleral Suture Fixation of an Injector-delivered Intraocular Lens

Purpose: We evaluated a novel surgical technique for managing the intraocular lens (IOL) through in situ scleral fixation and its outcomes.Case summary: This retrospective case series included three eyes of three patients treated with the in situ scleral fixation technique for IOL. Our method involves suturing the haptics of an already intraocularly injected IOL in situ using a Siepser sliding knot suture, while the other haptic is tied externally. Notably, no intraoperative or postoperative complications, such as cystoid macula edema, were observed.Conclusions: This novel technique is a user-friendly and effective approach to improve IOL-capsular bag stability, requiring minimal intraocular intervention or preoperative preparation compared to conventional IOL scleral fixation methods. Furthermore, it is particularly effective for addressing concerns related to IOL-capsular bag stability following IOL insertion, as it eliminates the possibility of performing the typical IOL scleral fixation due to the absence of preoperative preparation and evaluation.

Retrospective Review and Analysis on Outcome of Cranioplasty: A Series of 38 Cases

Background: Cranioplasty (CP) is a straightforward procedure, it may result in a significant number of complications. These include infections, seizures, intracranial hematomas, and others. Objective: This was a retrospective study on outcome of Cranioplasty. Materials and Methods: This retrospective study included patients who underwent decompressive craniectomy due to traumatic brain injury with raised ICP, acute subdural hematoma, compound comminuted skull fracture & ICH, between January January 2019 to December 2020 at Enam Medical College & Hospital, Savar, Dhaka. Data were collected in pre-designed data collection sheet and were analyzed using computerbased programme statistical package for social science (SPSS) windows version 25. Results: This study showed maximum patients (34.2%) were between 21-30 years age. Majority were male (89.5%) and only 5.9% were female. Overall rate of complications was 10.5%. Among them new onset seizure (n = 4), indrawing of skin through bone gap (n=4), hemorrhage (n=2), infection (n = 1), HCP (n = 1), and exposed implant (n=1). Conclusion: We have found the outcome of cranioplasty was better with titanium mesh plate and screw than conventional fixation of bone with polyglactin, polypropylene suture and titanium miniplate and screw. With polypropylene and polyglactin there is more chance of inward displacement of bone fragment and with miniplate and screw there is still chance of indrawing of bone fragment through the bone gap. Bang. J Neurosurgery 2023; 13(1): 20-23

IMF screws with orthodontic E chains as a novel technique for intermaxillary fixation

AbstractIntroductionEither in conservative or in surgical management of maxillo‐mandibular fractures, intermaxillary fixation (IMF) provides stable occlusion, while offering reduction in the fractured segments. Various techniques have been used for achieving IMF, among which Erich arch bar is the most conventional and routinely used technique. However, it poses a risk of percutaneous injury to the surgical team with every wire used in the technique, causes trauma to the periodontium of the teeth secured by wires and it is not very comfortable for the patient. The few IMF techniques that are recommended without wire require special armamentarium that are not universally available.Materials and MethodsOur novel IMF technique employing multiple looping of orthodontic E chains around IMF screws can provide adequate reduction and stabilization of the fractured segments with good occlusion before plating of the maxillo‐mandibular fractures. It can also be utilized for extended periods for closed reduction or postoperatively for guiding the occlusion.ResultsAs seen in our clinical experience using this novel technique, there is no risk of percutaneous injury to the surgical team. It provides stable occlusion, optimal reduction in the fractured segments and is accepted well by patients as no wires are used.ConclusionThis novel technique can be used in all patients who require IMF and is particularly useful in patients with periodontally compromised teeth or in those who are partially edentulous where conventional arch bar fixation cannot be performed. This technique will considerably reduce the operative time and aid in better patient compliance.

Rapid Freezing and Cryo-SEM-EDS Imaging of Foraminifera (Unicellular Eukaryotes) Using a Conductive Viscous Cryogenic Glue.

Spatial distribution of water-soluble molecules and ions in living organisms is still challenging to assess. Energy-dispersive X-ray spectroscopy (EDS) via cryogenic scanning electron microscopy (cryo-SEM) is one of the promising methods to study them without loss of dissolved contents. High-resolution cryo-SEM-EDS has challenges in sample preparation, including cross-section exposure and sample drift/charging due to insulative surrounding water. The former becomes problematic for large and inseparable organisms, such as benthic foraminifera, a unicellular eukaryote playing significant roles in marine ecosystems, which often exceed the size limit for the most reliable high-pressure freezing. Here we show graphite oxide dispersed in sucrose solution as a good glue to freeze, expose cross-section by cryo-ultramicrotome, and analyze elemental distribution owing to the glue's high viscosity, adhesion force, and electron conductivity. To demonstrate the effectiveness and applicability of the glue for cryo-SEM-EDS, deep-sea foraminifer Uvigerina akitaensis was sampled during a cruise and plunge frozen directly on the research vessel, where the liquid nitrogen supply is limited. The microstructures were preserved as faithfully in cryo-SEM images as those with the conventional resin-substituted transmission electron micrograph. We found elements colocalized within the cytoplasm originating from water-soluble compounds that can be lost with conventional dehydrative fixation.

Peripheral Wavefront Sensor with Fixation Target Made by Optical Simulation for Measuring Human Eye Regardless of Spectacle

This study proposes a custom-built aberrometer that measures peripheral defocus to evaluate myopia progression in the human eye. This advanced device can measure visual fields in both horizontal (up to 40°) and vertical (up to 30°) orientations. It incorporates a novel fixation target that is meticulously designed using an optical simulation software. Notably, each angular point of this novel fixation target differs considerably from the conventional fixation target. To mitigate the effects of the optical variations introduced by spectacles and the subject’s vision, we incorporated a position-variable lens positioned in front of the eye. This lens compensates for these variations, enhancing the precision of the measurements. To evaluate the performance of the proposed aberrometer, we conducted experiments under three distinct conditions: first, with the naked eye; second, while wearing spectacles; and third, while wearing a multifocal lens.

Arthroscopic Assisted Reduction of Talus Fractures Leads to Improved Clinical Outcomes at Mid- Term Follow-Up

Introduction/Purpose: Talus fracture is an uncommon and challenging pathology to treat due to its relationship with articular cartilage, ligamentous network, and avascular nature. The purpose of this systematic review was to evaluate the clinical outcomes after arthroscopic talar fracture fixation, compare to conventional open reduction and internal fixation (ORIF), and analyze the quality and level of evidence of the included studies. Methods: A systematic review of the MEDLINE, EMBASE, and Cochrane Library databases was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in June 2023. Articles were included if they evaluated outcomes following arthroscopic treatment of talus fractures, were written in English, were peer-reviewed, had a minimum of 2 patients per cohort, had human patients, and had a minimum 6-month follow-up. Inclusion criteria consisted of: Studies reporting clinical data following arthroscopy for the treatment of talus fractures were included and assessed. Results: Seven studies were analyzed, including 4 case series, 1 retrospective cohort, and 2 retrospective comparative studies. 237 patients treated with arthroscopic assisted reduction were compared to 76 patients treated with ORIF. Amongst arthroscopically treated patients, the AOFAS score improved from 71.2 ± 5.2 preoperatively to 89.9 ± 4.3 postoperatively. The SF-36 score improved from 73.2 ± 30.3 preoperatively to 104.5 ± 19.3 postoperatively. In total, 6 complications (3.0%) were observed in arthroscopically treated patients, of which the most common was peri-talar osteoarthritis in 2 patients (0.84%). In comparative cohorts, ORIF patients experienced a 13.0% complication rate in 6 patients (talar necrosis, malunion, nonunion, infection, and post-traumatic arthritis), compared to 2.2% in 1 patient (malunion) in the arthroscopic cohort. Conclusion: This study demonstrates that arthroscopic assisted reduction of talar fractures results in good clinical outcomes with lower complication rates. This minimally invasive approach had lower complications than ORIF, with no cases of talar necrosis and decreased postoperative traumatic arthritis. This technique provides adequate exposure without additional osteotomy, while decreasing trauma to local anatomical trauma, minimizing the risk of postoperative complications, and improving fracture healing assessment of concomitant lesions. These findings indicate arthroscopic treatment of talus fractures is an efficacious and safe procedure with comparable or improved clinical and postoperative outcomes as compared to conventional ORIF.

A Propensity Score-Matched Cohort Study Comparing 3 Different Spine Pedicle Screw Fixation Methods: Freehand, Fluoroscopy-Guided, and Robot-Assisted Techniques.

This study aimed to compare the accuracy of robotic spine surgery and conventional pedicle screw fixation in lumbar degenerative disease. We evaluated clinical and radiological outcomes to demonstrate the noninferiority of robotic surgery. This study employed propensity score matching and included 3 groups: robot-assisted mini-open posterior lumbar interbody fusion (PLIF) (robotic surgery, RS), c-arm guided minimally invasive surgery transforaminal lumbar interbody fusion (C-arm guidance, CG), and freehand open PLIF (free of guidance, FG) (54 patients each). The mean follow-up period was 2.2 years. The preoperative spine condition was considered. Accuracy was evaluated using the Gertzbein-Robbins scale (GRS score) and Babu classification (Babu score). Radiological outcomes included adjacent segmental disease (ASD) and mechanical failure. Clinical outcomes were assessed based on the visual analogue scale, Oswestry Disability Index, 36-item Short Form health survey, and clinical ASD rate. Accuracy was higher in the RS group (p < 0.01) than in other groups. The GRS score was lower in the CG group, whereas the Babu score was lower in the FG group compared with the RS group. No significant differences were observed in radiological and clinical outcomes among the 3 groups. Regression analysis identified preoperative facet degeneration, GRS and Babu scores as significant variables for radiological and clinical ASD. Mechanical failure was influenced by the GRS score and patients' age. This study showed the superior accuracy of robotic spine surgery compared with conventional techniques. When combined with minimally invasive surgery, robotic surgery is advantageous with reduced ligament and muscle damage associated with traditional open procedures.

Nonmetallic tension band fixation is a viable and low-complication surgical technique in patellar fractures: a five-year retrospective study.

Traditionally, patellar fractures (PFs) have been managed using metallic tension band fixation, a method often associated with a notable rate of complications. Considering these challenges, this study explores the potential of nonmetallic fixation as a treatment option for PFs. This research aims to provide robust evidence supporting the use of the nonmetallic tension band fixation technique as an effective alternative to conventional metallic tension band fixation, thereby advancing the standard of care in treating these fractures. This retrospective study analyzed a consecutive patient series presenting with PFs from 2008 to 2021, treated with a nonmetallic tension band fixation technique. Inclusion criteria were strictly defined to include individuals over 18years of age with isolated PFs requiring surgical intervention. The study focused on evaluating postoperative complications and clinical outcomes, as measured by standardized scoring systems, at the final follow-up point to assess the efficacy and safety of the employed surgical technique. In this study, with a mean follow-up of 64 ± 7months, a total of 64 patients who received open reduction and internal fixation (ORIF) for PFs were enrolled. Among these, five cases required additional surgical interventions. Specifically, two cases were due to knee stiffness, while the remaining three involved complications such as superficial infection, skin irritation, or delayed wound healing. The mean postoperative values recorded for the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Oxford knee score (OKS), and visual analog scale (VAS) were 20.4 ± 2.3, 35.5 ± 5.3, and 1.6 ± 0.4, respectively. There were no complications related to the nonmetallic fixation technique or instances of loss of reduction. This study substantiates that nonmetallic tension band fixation is a safe and effective alternative to traditional metallic tension band fixation for patellar fractures. The study's low-complication rate and reoperation frequency underscore the value of nonmetallic implants in mitigating adverse effects and enhancing clinical outcomes. IV.

Unilateral Biplanar Screw-Rod Fixation Technique for the Treatment of Odontoid Fractures in Patients with Atlantoaxial Bone or Vascular Abnormalities

This study aims to introduce the Unilateral Biplanar Screw-Rod Fixation (UBSF) technique (A hybrid fixation technique: Two sets of atlantoaxial screws were placed on the same side), which serves as a salvage method for traditional posterior atlantoaxial fixation. To summarize the indications of this technique and to assess its safety, feasibility, and clinical effectiveness in the treatment of odontoid fractures. Patients with odontoid fractures were enrolled according to special criteria. Surgical duration and intraoperative blood loss were documented. Patients were followed up for a minimum of 12 months. X-ray and CT scans were conducted and reviewed at 1 day, and patients asked return for CT reviews at 3, 6, 9, and 12 months after surgery until fracture union. Recorded and compared the Neck Visual Analog Scale and Neck Disability Index pre-surgery and at one week and 12 months post-surgery. Between January 2016 to December 2022, our study enrolled 7 patients who were diagnosed with odontoid fractures accompanied by atlantoaxial bone or vascular abnormalities. All 7 patients underwent successful UBSF surgery, and no neurovascular injuries were recorded during surgery. Fracture union was observed in all patients, and the Neck VAS and NDI scores improved significantly at 1 week and 12 months postoperative (P < 0.01). The UBSF technique has been demonstrated to be safe, feasible, and effective in treating odontoid fractures. In cases where the atlantoaxial bone or vascular structure exhibits abnormalities, it can function as a supplementary or alternative approach to the conventional posterior C1-2 fixation.

Exploring the Application of Graphene Oxide-Based Nanomaterials in the Repair of Osteoporotic Fractures.

Osteoporotic fractures are induced by osteoporosis, which may lead to the degradation of bone tissues and microstructures and impair their healing ability. Conventional internal fixation therapies are ineffective in the treatment of osteoporotic fractures. Hence, developing tissue engineering materials is crucial for repairing osteoporotic fractures. It has been demonstrated that nanomaterials, particularly graphene oxide (GO), possess unique advantages in tissue engineering due to their excellent biocompatibility, mechanical properties, and osteoinductive abilities. Based on that, GO-nanocomposites have garnered significant attention and hold promising prospects for bone repair applications. This paper provides a comprehensive insight into the properties of GO, preparation methods for nanocomposites, advantages of these materials, and relevant mechanisms for osteoporotic fracture applications.

Bone cement reinforcement improves the therapeutic effects of screws in elderly patients with pelvic fragility factures

BackgroundPelvic fragility fractures in elderly individuals present significant challenges in orthopedic and geriatric medicine due to reduced bone density and increased frailty associated with aging.MethodsThis study involved 150 elderly patients with pelvic fragility fractures. The patients were divided into two groups, the observation group (Observation) and the control group (Control), using a random number table. Artificial intelligence, specifically the Tianji Orthopedic Robot, was employed for surgical assistance. The observation group received bone cement reinforcement along with screw fixation using the robotic system, while the control group received conventional screw fixation alone. Follow-up data were collected for one-year post-treatment.ResultsThe observation group exhibited significantly lower clinical healing time of fractures and reduced bed rest time compared to the control group. Additionally, the observation group experienced less postoperative pain at 1 and 3 months, indicating the benefits of bone cement reinforcement. Moreover, patients in the observation group demonstrated significantly better functional recovery at 1-, 3-, and 6-months post-surgery compared to the control group.ConclusionThe combination of bone cement reinforcement and robotic technology resulted in accelerated fracture healing, reduced bed rest time, and improved postoperative pain relief and functional recovery.

Evaluation of stability of fixation using conventional miniplate osteosynthesis in comminuted and non-comminuted Le Fort I, II, III fractures – A dynamic finite element analysis

Purpose: The purpose of the present study was to evaluate and compare the stability of fixation using conventional miniplate osteosynthesis in comminuted and non-comminuted Le Fort I, II, and III fractures in open and closed jaw movements under masticatory loading conditions.Materials and Methods: About 23 dimensional models of comminuted and non-comminuted Le Fort I, II, and II with traditional miniplate fixation were simulated virtually using a CT scan of the patient and analyzed using ANSYS Workbench 2020 R1 software. The dynamic finite element method was applied by the simulation of the forces of the muscles of mastication upon the fractured midface. The von Mises stress was analyzed and collated for each model; thereby, the stability of conventional miniplate fixation was interpreted.Results: The von Mises stress over the regions of fixation were compared and the tabulated data was interpreted. Considerable von Mises stress was generated on the bone and deformation over the hardware was noted on the pyriform rim in the Le Fort I model, infraorbital rim in the Le Fort II model, and frontonasal region in the Le Fort III model in the closing phase of jaw movement.Conclusion: The findings implicated that the biomechanical stability of conventional miniplate osteosynthesis is insufficient to secure the midface fractured bone under masticatory load.

Fixation method of a single muscle fiber by magnetic force for stretching, transportation, and evaluation of mechanical properties

Engineered muscle fibers are attracting interest in bio-actuator research as they can contribute to the fabrication of actuators with a high power/size ratio for micro-robots. These fibers require to be stretched during culture for functional regulation as actuators and require a fixation on a rigid substrate for stretching in culture and evaluation of mechanical properties, such as Young’s modulus and contraction force. However, the conventional fixation methods for muscle fibers have many restrictions as they are not repeatable and the connection between fixation part and the muscle fibers detaches during culture; therefore, the fixation becomes weak during culture, and direct measurement of the muscle fibers’ mechanical properties by a force sensor is difficult. Therefore, we propose a facile and repeatable fixation method for muscle fibers by mixing magnetite nanoparticles at both ends of the muscle fibers to fabricate magnetic ends. The fiber can be easily attached and detached repeatedly by manipulating a magnet that applies a magnetic force larger than 3 mN to the magnetic ends. Thus, the muscle fiber can be stretched fiber during culture for functional regulation, transported between the culture dish and measurement system, and directly connected to the force sensor for measurement with magnetic ends. The muscle fiber connected with magnetic ends have a long lifetime (∼4 weeks) and the cells inside had the morphology of a skeletal muscle. Moreover, the muscle fiber showed a contraction (specific force of 1.02 mN mm−2) synchronized with electrical stimulation, confirming the muscle fiber fabricated and cultured using our method had similar morphology and function as bio-actuators in previous research. This research demonstrates the advantages of the fixation method using muscle fibers with magnetic ends; the fibers are stretched during culture, and the transportation and force measurement of weak and tiny muscle fibers could be finished in 1 min.

Pin penetration depths in the neurocranium using a three-pin head fixation device

In estimated 10–15% of neurosurgical interventions employing a conventional three-pin head fixation device (HFD) the patient’s head loses position due to slippage. At present no scientifically based stability criterion exists to potentially prevent the intraoperative loss of head position or skull fractures. Here, data on the skull penetration depth both on the single and two-pin side of a three-pin HFD are presented, providing scientific evidence for a stability criterion for the invasive three-pin head fixation. Eight fresh, chemically untreated human cadaveric heads were sequentially pinned 90 times in total in a noncommercially calibrated clamp screw applying a predefined force of 270 N (approximately 60 lbf) throughout. Three head positions were pinned each in standardized manner for the following approaches: prone, middle fossa, pterional. Titanium-aluminum alloy pins were used, varying the pin-cone angle on the single-pin side from 36° to 55° and on the two-pin side from 25° to 36°. The bone-penetration depths were directly measured by a dial gauge on neurocranium. The penetration depths on the single-pin side ranged from 0.00 mm (i.e., no penetration) to 6.17 mm. The penetration depths on the two-pin side ranged from 0.00 mm (no penetration) to 4.48 mm. We measured a significantly higher penetration depth for the anterior pin in comparison to the posterior pin on the two-pin side in prone position. One pin configuration (50°/25°) resulted in a quasi-homogenous pin depth distribution between the single- and the two-pin side. Emanating from the physical principle that pin depths behave proportionate to pin pressure distribution, a quasi-homogenous pin penetration depth may result in higher resilience against external shear forces or torque, thus reducing potential complications such as slippage and depressed skull fractures. The authors propose that the pin configuration of 50°/25° may be superior to the currently used uniform pin-cone angle distribution in common clinical practice (36°/36°). However, future research may identify additional influencing factors to improve head fixation stability.

Is Proximal Triangular Fixation Better than the Conventional Method in Adult Spinal Deformity Surgery?

In adult spinal deformity (ASD) surgery, one of the key factors working to prevent proximal junctional kyphosis is the proximal anchor. The aim of this study was to compare clinical and radiographic outcomes of triangular fixation with conventional fixation as proximal anchoring techniques in ASD surgery. We retrospectively evaluated 54 patients who underwent corrective spinal fusion for ASD. Fourteen patients underwent proximal triangular fixation (Group T; average 74.6 years), and 40 patients underwent the conventional method (Group C; average 70.5 years). Clinical and radiographic outcomes were assessed using visual analogue scale (VAS) values for back pain and the Oswestry disability index (ODI). Radiographic evaluation was also collected preoperatively and postoperatively. Surgical times and intraoperative blood loss of the two groups were not significantly different (493 vs 490 min, 1,260 vs 1,173 mL). Clinical outcomes such as VAS and ODI were comparable in the two groups. Proximal junctional kyphosis in group T was slightly lower than that of group C (28.5% vs 47.5%, p=0.491). However, based on radiology, proximal screw pullout occurred significantly less frequently in the triangular fixation group than the conventional group (0.0% vs 22.5%, p=0.049). Clinical outcomes in the two groups were not significantly different.

Exploring Advanced Functionalities of Carbon Fiber-Graded PEEK Composites as Bone Fixation Plates Using Finite Element Analysis.

This study aims to address the challenges associated with conventional metallic bone fixation plates in biomechanical applications, such as stainless steel and titanium alloys, including stress shielding, allergic reactions, corrosion resistance, and interference with medical imaging. The use of materials with a low elastic modulus is regarded as an effective approach to overcome these problems. In this study, the impact of different types of chopped carbon fiber-reinforced polyether ether ketone (CCF/PEEK) functionally graded material (FGM) bone plates on stress shielding under static and instantaneous dynamic loading was explored using finite element analysis (FEA). The FGM bone plate models were established using ABAQUS and the user's subroutine USDFLD and VUSDFLD, and each model was established with an equivalent overall elastic modulus and distinctive distributions. The results revealed that all FGM bone plates exhibited lower stress shielding effects compared to metal bone plates. Particularly, the FGM plate with an elastic modulus gradually increased from the centre to both sides and provided maximum stress stimulation and the most uniform stress distribution within the fractured area. These findings offer crucial insights for designing implantable medical devices that possess enhanced mechanical adaptability.

Connecting the S2 alar-iliac screw head to the satellite rod for surgical correction of degenerative sagittal imbalance.

The S2AI screw technique has several advantages over the conventional iliac screw fixation technique. However, connecting the S2AI screw head to the main rod is difficult due to its medial entry point. We introduce a new technique for connecting the S2AI screw head to a satellite rod and compare it with the conventional method of connecting the S2AI screw to the main rod. Seventy-four patients who underwent S2AI fixation for degenerative sagittal imbalance and were followed up for ≥ 2years were included. All the patients underwent long fusion from T9 or T10 to the pelvis. The S2AI screw head was connected to the satellite rod (SS group) in 43 patients and the main rod (SM group) in 31 patients. In the SS group, the satellite rod was placed medial to the main rod and connected by the S2AI screw and domino connectors. In the SM group, the main rod was connected directly to the S2AI screw head and supported by accessory rods. Radiographic and clinical outcomes were evaluated in both groups. There were no significant differences in postoperative complications, including proximal junctional failure, proximal junctional kyphosis, rod breakage, screw loosening, wound problems, and infection between the two groups. Furthermore, the correction power of sagittal deformity and clinical results in the SS group were comparable to those in the SM group. Connecting the S2AI screw to the satellite rod is a convenient method comparable to the conventional S2AI connection method in terms of radiological and clinical outcomes.

Conformal Fixation Strategies and Bioadhesives for Soft Bioelectronics

AbstractFlexible wearable and implantable devices are contributing to the healthcare field by enabling intuitive interfaces with the tissues of human body through their thin form factors, which enable more accurate monitoring of signals and effective delivery of therapy. The development of such devices is accompanied with an increasing interest in strategies and technologies for conformally fixing and adhering flexible biomedical devices in place to acquire high‐quality biosignals over a long period, even with the subtle movements of the target. Owing to the various mechanical properties and wet or dynamic environments of human tissues, it is necessary to use different adhesion strategies that consider the biocompatibility and cohesive properties for each case. This paper provides an in‐depth analysis of recent bio‐adhesives technologies and their practical applications in the healthcare field by classifying them into: 1) Conventional Fixation, 2) Mechanical Fixation, and 3) Chemical Adhesion, based on the mechanism, and 4) Functional Adhesion and 5) Biomimetic Adhesion, based on the unique properties. Furthermore, the principles and detailed mechanisms of each adhesion strategy based on the design and characteristics of the bioadhesives are thoroughly reviewed to provide valuable insights and an overall summary of the prospects and challenges of future bioadhesives technology.

GLUEING OSTEOCHONDRAL FRAGMENTS: DEVELOPMENT OF A NOVEL DUAL ADHESIVE PRECLINICAL MODEL STRATEGY

The fixation of articular fractures, with many small osteochondral fragments, is a challenging unmet need where a bone adhesive would be a useful adjunct to standard treatments. Whilst there are no such adhesives in current clinical use, preclinical animal models have demonstrated good healing of bone in unloaded models using an adhesive based on phosphoserine modified calcium phosphate cement (PM-CPC). An ex-vivo human bone core model has shown that this adhesive bonds freshly harvested human bone. To confirm this adhesive is capable of supporting loaded osteochondral fragments a porcine model has been developed initially ex-vivo on the path to an in-vivo study. In this model bone cores, harvested from the medial knee condyle, are glued in place with the adhesive. In-vivo adjacent pairs of bone cores would be replaced with adhesive and a control with conventional pin fixation respectively. As osteochondral bone fragments have both bone and cartilage components, this suggested a dual adhesive strategy in which components designed for each tissue type are used. This concept has been explored in an ex-vivo porcine pilot study presented herewith. At the subchondral bone level, the PM-CPC was used. At the cartilage level, a second adhesive, a methacrylated phosphoserine containing hyaluronic acid (MePHa) hydrogel designed specifically for soft tissues was applied. This is a challenging model as both adhesives have to be used simultaneously in a wet field. The pilot showed that once the subchondral component is glued in place, the PM-CPC adhesive intruding into the cartilage gap can be removed before applying the cartilage adhesive. This enabled the MePHa adhesive to be injected between the cut cartilage edges and subsequently light-cured. This two-stage gluing method is demanding and an in-vivo pilot is necessary to perfect and prove the operative technique.Acknowledgements: The human bone core project was partially financed by Innovation Fund of Västra Götaland Region, Sweden. The MePHa hydrogel work was supported by a Swiss National Fund grant # CR23I3_159301.