Absorbable biologically based internal fixation

Redefining Surgical Materials: Applications of Silk Fibroin in Osteofixation and Fracture Repair

Silk and silk derivatives have emerged as a possible alternative in surgical device development, offering mechanical strength, biocompatibility, and environmental sustainability. Through a systematic review following PRISMA guidelines, this study evaluated silk fibroin's application across pre-clinical and clinical settings, focusing on its role as screws and plates for osteofixation. A comprehensive search yielded 245 studies, with 33 subjected to full-text review and 15 ultimately included for qualitative analysis. The findings underscore silk fibroin's superior properties, including its tunable degradation rates and ability to be functionalized with therapeutic agents. In vivo and in vitro studies demonstrated its efficacy in enhancing bone healing, offering improved outcomes in osteofixation, particularly for craniofacial defects. Silk fibroin's remarkable attributes in biodegradation and drug release capabilities underscore its potential to enhance patient care. Ultimately, silk fibroin's integration into surgical practices promises a revolution in patient outcomes and environmental sustainability. Its versatility, coupled with the continuous progress in fabrication techniques, signals a promising horizon for its widespread acceptance in the medical field, potentially establishing a new benchmark in surgical treatment. Further research is expected to solidify the transition of silk products from basic science to patient care, paving the way for widespread use in various surgical applications.

Magnesium-based alloys with adapted interfaces for bone implants and tissue engineering

Magnesium and its alloys are one of the most used materials for bone implants and tissue engineering. They are characterized by numerous advantages such as biodegradability, high biocompatibility and mechanical properties with values close to the human bone. Unfortunately, the implant surface must be adequately tuned, or Mg-based alloys must be alloyed with other chemical elements due to their increased corrosion effect in physiological media. This article reviews the clinical challenges related to bone repair and regeneration, classifying bone defects and presenting some of the most used and modern therapies for bone injuries, such as Ilizarov or Masquelet techniques or stem cell treatments. The implant interface challenges are related to new bone formation and fracture healing, implant degradation and hydrogen release. A detailed analysis of mechanical properties during implant degradation is extensively described based on different literature studies that included in vitro and in vivo tests correlated with material properties' characterization. Mg-based trauma implants such as plates and screws, intramedullary nails, Herbert screws, spine cages, rings for joint treatment and regenerative scaffolds are presented, taking into consideration their manufacturing technology, the implant geometrical dimensions and shape, the type of in vivo or in vitro studies and fracture localization. Modern technologies that modify or adapt the Mg-based implant interfaces are described by presenting the main surface microstructural modifications, physical deposition and chemical conversion coatings. The last part of the article provides some recommendations from a translational perspective, identifies the challenges associated with Mg-based implants and presents some future opportunities. This review outlines the available literature on trauma and regenerative bone implants and describes the main techniques used to control the alloy corrosion rate and the cellular environment of the implant.

Clinical Use of Non-Suture Silk-Containing Products: A Systematic Review

AIMS

The purpose of this systematic review is to determine how various innovative non-suture silk and silk-containing products are being used in clinical practice, and compare patient outcomes following their use.

METHODS

A systematic review of PubMed, Web of Science, and Cochrane was completed. A qualitative synthesis of all included studies was then performed.

RESULTS

Our electronic search identified 868 silk-related publications, which yielded 32 studies for full-text review. After exclusion, nine studies from 2011 to 2018 were included for qualitative analysis. A total of 346 patients were included which consisted of 37 males and 309 females. The mean age range was between 18-79 years old. The follow-up among studies ranged between one to twenty-nine months. Three studies addressed the application of silk in wound dressings, one on the topical application of silk-derived products, one on silk-derived scaffold in breast reconstruction, and three on silk underwear as adjunct for the treatment of gynecological conditions. All studies showed good outcomes alone or in comparison to controls.

CONCLUSION

This systematic review concludes that silk products' structural, immune, and wound-healing modulating properties are advantageous clinical assets. Nevertheless, more studies are needed to strengthen and establish the benefit of those products.

Biodegradable Bone Implants as a New Hope to Reduce Device-Associated Infections-A Systematic Review

Bone fractures often require fixation devices that frequently need to be surgically removed. These temporary implants and procedures leave the patient more prone to developing medical device-associated infections, and osteomyelitis associated with trauma is a challenging complication for orthopedists. In recent years, biodegradable materials have gained great importance as temporary medical implant devices, avoiding removal surgery. The purpose of this systematic review was to revise the literature regarding the use of biodegradable bone implants in fracture healing and its impact on the reduction of implant-associated infections. The systematic review followed the PRISMA guidelines and was conducted by searching published studies regarding the in vivo use of biodegradable bone fixation implants and its antibacterial activity. From a total of 667 references, 23 studies were included based on inclusion and exclusion criteria. Biodegradable orthopedic implants of Mg-Cu, Mg-Zn, and Zn-Ag have shown antibacterial activity, especially in reducing infection burden by MRSA strains in vivo osteomyelitis models. Their ability to prevent and tackle implant-associated infections and to gradually degrade inside the body reduces the need for a second surgery for implant removal, with expectable gains regarding patients’ comfort. Further in vivo studies are mandatory to evaluate the efficiency of these antibacterial biodegradable materials.

The Role of Long Non-Coding RNAs and Circular RNAs in Bone Regeneration: Modulating MiRNAs Function

Although bone is a self-healing organ and is able to repair and restore most fractures, large bone fractures, about 10%, are not repairable. Bone grafting, as a gold standard, and bone tissue engineering using biomaterials, growth factors, and stem cells have been developed to restore large bone defects. Since bone regeneration is a complex and multiple-step process and the majority of the human genome, about 98%, is composed of the non-protein-coding regions, non-coding RNAs (ncRNAs) play essential roles in bone regeneration. Recent studies demonstrated that long ncRNAs (lncRNAs) and circular RNAs (circRNAs), as members of ncRNAs, are widely involved in bone regeneration by interaction with microRNAs (miRNAs) and constructing a lncRNA or circRNA/miRNA/mRNA regulatory network. The constructed network regulates the differentiation of stem cells into osteoblasts and their commitment to osteogenesis. This review will present the structure and biogenesis of lncRNAs and circRNAs, the mechanism of bone repair, and the bone tissue engineering in bone defects. Finally, we will discuss the role of lncRNAs and circRNAs in osteogenesis and bone fracture healing through constructing various lncRNA or circRNA/miRNA/mRNA networks and the involved pathways. This article is protected by copyright. All rights reserved.

A high-strength biodegradable thermoset polymer for internal fixation bone screws: Preparation, in vitro and in vivo evaluation

Thermoset polymers synthesized from the polycondensation of glycerol with biocompatible diacids represent a promising class of absorbable materials for biomedical applications. However, the utility of these polymers for bone fixation devices is hampered due to the lack of mechanical strength. Herein we synthesized a high-strength thermoset polymer, poly(glycerol-succinate) (PGS), via a catalyst-free and solvent-free reaction. The bending strength of PGS reaches 122.01 ± 8.82 MPa, signifying its great potential for fixation devices. The degradation property of the polymer can be tuned by adjusting the monomer ratio and reaction time. Bone screws based on the PGS polymer were successfully manufactured using a lathe. In vitro evaluation showed the PGS polymer was able to well support cell adhesion and proliferation. In vivo evaluation using a rat subcutaneous implantation model showed that the inflammatory response to the polymer was mild. After the PGS screws were implanted in the rabbit femoral condyle for 12 weeks, micro-computed tomography (micro-CT) and histological analysis revealed that the screws achieved good osseointegration. Consequently, the polymer developed in current study can serve as internal fixation devices due to the proper mechanical strength, excellent biocompatibility, and feasibility of manufacturing screws.

Bioabsorbable implants in foot trauma surgery

BACKGROUND

Resorbable osteosynthesis has been used in orthopaedic surgery for many years. However, indications for the use of these implants in the surgery of traumatic lesions of the foot have not yet been clearly defined. The aim of this study is to analyse reported experiences with the bioabsorbable devices and to suggest guidelines for their use in foot trauma surgery METHODS: We conducted a literature review to identify known indications for the use of absorbable devices in traumatic lesions of the foot. We also conducted a retrospective analysis of our registry, reviewing patients with traumatic lesions of the foot who were treated surgically with absorbable devices from November 2005 to January 2017. To this end, we analysed for each case the indication for the use of resorbable devices and the incidence of related complications.

RESULTS

Only 14 relevant studies were found. In the selected period, 76 patients were treated using bioabsorbable devices for a traumatic lesion of the foot. Nine patients were lost to follow-up or did not satisfy the inclusion criteria. Therefore, the final size of the registry was 67 patients. The average follow-up was 20.5 months (range 6-66). All the bioabsorbable devices used were screws and bars of poly-L-lactic acid (PLLA). The indications identified in the literature review and in our registry were osteosynthesis of small periarticular fragments in talus and calcaneus fractures, preliminary stabilisation of articular fragments in Sanders III calcaneal fractures and fracture-dislocations of the Lisfranc or Chopart joints. No foreign-body reactions occurred. However, in one case we registered a late mobilisation of a PLLA bar in a healed calcaneal fracture, probably as a consequence of surgical malpositioning of the device. All the operated lesions demonstrated a normal healing time, and the complication rate was comparable with those of other types of osteosynthesis.

CONCLUSION

In foot trauma surgery the use of absorbable devices can give advantages. The most clearly defined indications are osteosynthesis of peri-articular or articular fragments in talus and calcaneus fractures, Sanders III calcaneal fractures and fracture-dislocations of Lisfranc's or Chopart's joints. Foreign-body reactions are rare and seem not to present a problem.

Bacterial osteomyelitis in veterinary orthopaedics: Pathophysiology, clinical presentation and advances in treatment across multiple species

Bacterial osteomyelitis in veterinary patients can be challenging to diagnose and treat, given limited therapeutic options and reported success rates. Osteomyelitis is frequently associated with surgical implant devices, including those required to optimise stability and healing of fractures. However, management of osteomyelitis sometimes necessitates the removal of these surgical implant devices in order to eradicate infection or limit implant-related osteolysis. The goal of this article is to provide a general and species-specific review of bacterial osteomyelitis in a selection of domestic veterinary species, including cats, dogs, horses, cattle and camelids, with a focus on classification, clinical presentation, aetiologic agents, and common therapeutic interventions reported in the literature. New treatment options emerging from research and human medicine will be also discussed, as they also apply to current or future care of veterinary patients with osteomyelitis.

Pathology of Bioabsorbable Implants in Preclinical Studies

Bioabsorbable implants can be advantageous for certain surgical tissue bioengineering applications and implant-assisted tissue repair. They offer the obvious benefits of nonpermanence and eventual restoration of the native tissue’s biomechanical and immunological properties, while providing a structural scaffold for healing and a route for additional therapies (i.e., drug elution). They present unique developmental, imaging, and histopathological challenges in the conduct of preclinical animal studies and in interpretation of pathology data. The bioabsorption process is typically associated with a gradual decline (over months to years) in structural strength and integrity and may also be associated with cellular responses such as phagocytosis that may confound interpretation of efficacy and safety end points. Additionally, as these implants bioabsorb, they become increasingly difficult to isolate histologically and thus imaging modalities such as microCT become very valuable to determine the original location of the implants and to assess the remodeling response in tandem with histopathology. In this article, we will review different types of bioabsorbable implants and commonly used bioabsorbable materials; additionally, we will address some of the most common challenges and pitfalls confronting histologists and pathologists in collecting, handling, imaging, preparing tissues through histology, evaluating, and interpreting study data associated with bioabsorbable implants.

New fabrication method of silk fibroin plate and screw based on a centrifugal casting technique

Recently, a newer generation of absorbable biomaterials has been developed from silk. Silk is approved by the US Food and Drug Administration, has robust mechanical features, and is biocompatible. Moreover, it offers the ability to be functionalized with bioactive compounds, making it ideal for use in new medical devices. Thus, many researchers have considered that absorbable devices made from silk may be able to overcome current limitations and could be used to meet a broader range of fixation needs. Here, we describe a novel method for the fabrication of silk fibroin (SF)-based bioabsorbable fixation systems using a centrifugal casting technique and incorporating a 3D printer. This approach allows us to create the desired geometric design for the fixation system easily. Moreover, our products demonstrated smoother surface profiles and more homogenous and dense cross-sectional architectures. Furthermore, our plates exhibited very similar mechanical properties compared with commercially used one, and our screws showed more than 70% of their initial mass after 7 weeks on the enzymatic degradation test. On in vivo analysis, we found that our devices were well-maintained in the location of initial fixation, and new bone formation was also observed around this. By these results, we suggest that the SF-based plate/screw prepared by our novel method might be used for the internal fixation of fracture sites.

Current status on clinical applications of magnesium-based orthopaedic implants: A review from clinical translational perspective

As a new generation of medical metallic material, magnesium (Mg) and its alloys with or without surface coating have attracted a great deal of attention due to its biodegradability and potential for avoiding a removal operation after the implant has fulfilled its function for surgical fixation of injured musculoskeletal tissues. Although a few clinical cases on Mg-based orthopaedic implants were reported more than a century ago, it was not until recently that clinical trials using these implants with improved physicochemical properties were carried out in Germany, China and Korea for bone fracture fixation. The promising results so far suggest a bright future for biodegradable Mg-based orthopaedic implants and would warrant large scale phase II/III studies. Given the increasing interest on this emerging biomaterials and intense effort to improve its properties for various clinical applications, this review covers the evolution, current strategies, and future perspectives in the development of Mg-based orthopaedic implants. We also highlight a few clinical cases performed in China that may be unfamiliar to the general orthopaedic community.