Traditional Metallic Implants Research Articles

Fluoride-treated rare earth-free magnesium alloy ZK30: An inert and bioresorbable material for bone fracture treatment devices.

Bone fractures represent a common health problem, particularly in an increasingly aging population. Bioresorbable magnesium (Mg) alloy-based implants offer promising alternatives to traditional metallic implants for the treatment of bone fractures because they eliminate the need for implant removal after healing. The Mg-Y-rare-earth (RE)-Zr alloy WE43, designed for orthopedic implants, has received European Conformity mark approval. However, currently, WE43 is not clinically used in certain countries possibly because of concerns related to RE metals. In this study, we investigated the use of a RE-free alloy, namely, Mg-Zn-Zr alloy (ZK30), as an implant for bone fractures. Hydrofluoric acid (HF) treatment was performed to improve the corrosion resistance of ZK30. HF-treated ZK30 (HF-ZK30) exhibited lower corrosion rate and higher biocompatibility than those of WE43 in in vitro experiments. After implanting a rod of HF-ZK30 into the fractured femoral bones of mice, HF-ZK30 held the bones and healed the fracture without deformation. Treatment results of HF-ZK30 were comparable to those of WE43, indicating the potential of HF-ZK30 as a bioresorbable and safe implant for bone repair.

Carbon-fiber-reinforced polyetheretherketone orthopedic implants in musculoskeletal and spinal tumors: imaging and clinical features.

Carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) orthopedic implants are gaining popularity in oncologic applications as they offer many potential advantages over traditional metallic implants. From an imaging perspective, this instrumentation allows for improved evaluation of adjacent anatomic structures during radiography, computed tomography (CT), and magnetic resonance imaging (MRI). This results in improved postoperative surveillance imaging quality as well as easier visualization of anatomy for potential image-guided percutaneous interventions (e.g., pain palliation injections, or ablative procedures for local disease control). CFR-PEEK devices are also advantageous in radiation oncology treatment due to their decreased imaging artifact during treatment planning imaging and decreased dose perturbation during radiotherapy delivery. As manufacturing processes for CFR-PEEK materials continue to evolve and improve, potential orthopedic applications in the spine and appendicular skeleton increase. An understanding of the unique properties of CFR-PEEK devices and their impact on imaging is valuable to radiologists delivering care to orthopedic oncology patients in both the diagnostic and interventional settings. This multidisciplinary review aims to provide a comprehensive insight into the radiologic, surgical, and radiation oncology impact of these innovative devices.

Multimodal imaging of composite carbon fiber-based implants for orthopedic spinal fixation.

As cancer treatments continue to improve, the incidence of spinal metastases and the need for surgical management of these with fixation procedures are growing rapidly. Traditionally metallic implants, composed of titanium alloy, have been used in surgical fixation of unstable or symptomatic vertebral metastases or traumatic injuries. Metallic implants, however, cause significant artifact on post-operative imaging, degrading image quality and limiting interpretation, and can also impair the planning and delivery of radiotherapy. Composite carbon fiber-based materials, such as carbon fiber-reinforced polyetheretherketone (PEEK), have been developed to overcome these issues and are now available for spinal fixation procedures. We aimed to review the multimodal imaging features of these new implants. Current literature and a case example from our institution were used to describe the multimodal imaging characteristics and considerations of new carbon fiber-based spinal fixation implants. New carbon fiber-based spinal implants allow far greater visualization of surrounding structures on post-operative cross-sectional imaging, significantly improving diagnostic accuracy and precision of radiotherapy planning, and do not significantly absorb or scatter X-ray photons during radiotherapy delivery. There are, however, important surgical and radiologic considerations associated with the use of carbon fiber-based implants which radiologists must be aware of, such as implications for surgical planning and intra-operative fluoroscopic and post-operative plain radiographic imaging. The use of carbon fiber-based implants, rather than traditional metallic implants, for spinal fixation offers significant advantages for post-operative diagnostic imaging and radiotherapy planning and delivery.

Patellar Fracture Fixation Using Suture Tape Cerclage

Transverse patellar fractures are a relatively common injury and typically require surgical fixation. An adequate restoration of patella integrity is essential for proper functioning of the extensor mechanism of the knee and for the prevention of patellofemoral osteoarthritis. Currently, the treatment of transverse fractures of the patellar bone involves several surgical techniques, most of which involve the use of metallic implants. Despite good clinical results following surgery, numerous complications exist, including primarily symptomatic hardware following surgical treatment. The purpose of this article is to describe the technique for treatment of a transverse patellar fracture using a high-resistance tape (FiberTape; Arthrex) and a tensioner (Arthrex) instead of traditional metallic implants.

The Advantages of Bioresorbable INION� Implants in Traumatology Design, polymer composition and preliminary results

Some disadvantages of traditional metallic implants used in orthopedics and traumatology prompted the development of bioresorbable polymer devices.The aim of this experimental study is to emphasize the characteristics of INION� resorbable implants (regarding design and polymers compositions), as well as to evaluate the results when using these innovative implants in two trauma cases. The polymers used in manufacturing INION� devices (Trimethylene Carbonate/TMC; L-Polylactic acid/LPLA; D,L Polylactic acid/DLPLA; Polyglycolic acid/PGA) degrade in alpha-hydroxy acids, gradually losing their hardness in 18-36 weeks with a complete bioresorption of 2-4 years. The clinical cases demonstrated the advantages of INION� plates (adapted shape, low profile, polyaxial screws, acceptable strength) or pins (allowing the aligmment and fixation of fracture, no migration). Among our patients, we found excellent results concerning the maintaining of primary reduced fracture, active range of motion, minimal pain with improving everyday comfort, no tissue or implant complications. Bioresorbable fracture fixation INION� devices are a viable alternative to traditional metallic implants, offering same significant advantages over them: the avoidance of long-term interference with gliding structures, keeping their strength long enough to support bone healing, no need to remove the implants, less pain, radiolucency, elimination of stress shielding and a lower risk of complications.

Treatment of calvarial defects by resorbable and non-resorbable sonic activated polymer pins and mouldable titanium mesh in two dogs: a case report

BackgroundTo date, calvarial defects in dogs have traditionally been addressed with different types of implants including bone allograft, polymethylmethacrylate and titanium mesh secured with conventional metallic fixation methods. This report describes the use of an absorbable and non absorbable novel polymer fixation method, Bonewelding® technology, in combination with titanium mesh for the repair of calvarial defects in two dogs. The clinical outcomes and comparative complication using resorbable and non-resorbable thermoplastic pins were compared.Case presentationThis report of two cases documents the repair of a traumatic calvarial fracture in an adult male Greyhound and a cranioplasty following frontal bone tumor resection in an adult female Cavalier King Charles Spaniel with the use of a commercially available titanium mesh secured with an innovative thermoplastic polymer screw system (Bonewelding®). The treatment combination aimed to restore cranial structure, sinus integrity and cosmetic appearance. A mouldable titanium mesh was cut to fit the bone defect of the frontal bone and secured with either resorbable or non-resorbable polymer pins using Bonewelding® technology. Gentamycin-impregnated collagen sponge was used intraoperatively to assist with sealing of the frontal sinuses. Calvarial fracture and post-operative implant positioning were advised using computed tomography. A satisfactory restoration of skull integrity and cosmetic result was achieved, and long term clinical outcome was deemed clinically adequate with good patient quality of life. Postoperative complications including rostral mesh uplift with minor associated clinical signs were encountered when resorbable pins were used. No postoperative complications were experienced in non-resorbable pins at 7 months follow-up, by contrast mesh uplift was noted 3 weeks post-procedure in the case treated using absorbable pins.ConclusionsThe report demonstrates the innovative use of sonic-activated polymer pins (Bonewelding® technology) alongside titanium mesh is a suitable alternative technique for skull defect repair in dogs. The use of Bonewelding® may offer advantages in reduction of surgical time. Further, ultrasonic pin application may be less invasive than alternative metallic fixation and potentially reduces bone trauma. Polymer systems may offer enhanced mesh-bone integration when compared to traditional metallic implants. The use of polymer pins demonstrates initial potential as a fixation method in cranioplasty. Initial findings in a single case comparison indicate a possible advantage in the use of non-absorbable over the absorbable systems to circumvent complications associated with variable polymer degradation, further long term studies with higher patient numbers are required before reliable conclusions can be made.

Use of intramedullary carbon fiber nail in hindfoot fusion: A small cohort study

BackgroundCurrent literature on carbon fiber implant use in foot and ankle surgery is scant. The purpose of this paper is to report medium-term outcomes of hindfoot fusion using a carbon fiber intramedullary nail. MethodsWe retrospectively reviewed 30 cases of hindfoot fusion using carbon fiber intramedullary nail fixation between 2014 and 2017. We excluded revisions and cases with bulk allograft or ankle infection prior to surgery. We reviewed charts for length of followup, radiographic union, and complications. ResultsEleven patients were included (6 females, 5 males; mean age=52±15years; mean BMI=29.0±6.4kg/m2). Mean followup was 20 (range, 1.5–107) months. Nine of eleven cases achieved radiographic union while one case developed a complication requiring surgery. The mean time to union was 3 (range, 1.5–6) months. ConclusionsCarbon fiber implants offer several theoretical advantages over traditional metallic implants. They can be used safely in foot and ankle surgery without concern for high failure or complication rate. Larger scale studies with longer followup are needed on this topic.

Corrosion behaviour of biodegradable magnesium alloys with hydroxyapatite coatings

Abstract Bioresorbable magnesium alloys are currently being investigated as implant materials to address the problems associated with traditional metallic implants. However, the use of magnesium in vivo has been limited due to its rapid corrosion in the presence of body fluids. This can result in the liberation of large amounts of hydrogen gas and alkalisation of the body fluid which, in turn, can inhibit wound healing and ultimately lead to necrosis of the surrounding tissue. Calcium phosphate coatings such as hydroxyapatite have been shown to reduce the corrosion rate of magnesium in vivo. Due to the low melting point of magnesium (≈ 600 °C) conventional high temperature techniques to deposit hydroxyapatite, such as plasma spray, are not suitable. This paper investigates the deposition of a hydroxyapatite coating onto the surface of three bioresorbable magnesium alloys using an ambient temperature, blast coating technique. The effect of the coating on the corrosion rate of the alloys in vitro is examined. The coated samples were examined using variety of techniques: x-ray diffraction (XRD), microscopy, elemental mapping, surface roughness and coating adhesion. The corrosion of the alloys was examined using an immersion testing, potentiodynamic polarization and electrochemical impedance spectroscopy. The coatings exhibited high bond strengths (≈ 48 MPa) with no detectable change in the coating's crystallinity after deposition. Each of the coated samples displayed lower corrosion rates than the uncoated equivalent sample. The results indicate that the process can be used to produce highly adherent coatings that decrease the corrosion rate of the alloys in vitro.

A carboxymethyl chitosan and peptide-decorated polyetheretherketone ternary biocomposite with enhanced antibacterial activity and osseointegration as orthopedic/dental implants.

Carbon fiber-reinforced polyetheretherketone (CFRPEEK) possesses biomechanical properties such as elastic modulus similar to human bones and is becoming a dominant alternative to replace the traditional metallic implants. The defective osseointegration and bacterial infection risk of CFRPEEK, however, impede its clinical adoption. In the current study, a newly-developed carbon fiber-reinforced polyetheretherketone/nanohydroxyapatite (CFRPEEK/n-HA) ternary biocomposite was functionalized by covalently grafting carboxymethyl chitosan (CMC) followed by the decoration of a bone-forming peptide (BFP) assisted via the polydopamine tag strategy. Antibacterial test with Staphylococcus aureus (S. aureus) indicated that the CMC and peptide-conjugated substrates (pep-CMC-CFRPEEK/n-HA) significantly suppressed bacterial adhesion. In vitro cell attachment/growth, spreading assay, alkaline phosphatase activity, real-time PCR analysis, osteogenesis-related protein expression and calcium mineral deposition all disclosed greatly accelerated adhesion, proliferation and osteo-differentiation of human mesenchymal stem cells (hMSCs) on the pep-CMC-CFRPEEK/n-HA biocomposite due to the additive effect of the CMC polysaccharide and the small osteoinductive peptide. More importantly, in vivo evaluation of the beagle tibia model by means of micro-CT, histological analysis, SEM observation and fluorescent labeling confirmed the remarkably boosted bioactivity and osteointegration. The CFRPEEK/n-HA ternary composite with the dual functions of bacterial adhesion reduction and osteointegration promotion holds great potential as a bioactive implant material in orthopedic/dental applications based on this scheme.

Peri-implant tissue response and biodegradation performance of a Mg–1.0Ca–0.5Sr alloy in rat tibia

Biodegradable magnesium (Mg) alloys combine the advantages of traditional metallic implants and biodegradable polymers, having high strength, low density, and a stiffness ideal for bone fracture fixation. A recently developed Mg–Ca–Sr alloy potentially possesses advantageous characteristics over other Mg alloys, such as slower degradation rates and minimal toxicity. In this study, the biocompatibility of this Mg–Ca–Sr alloy was investigated in a rat pin-placement model. Cylindrical pins were inserted in the proximal tibial metaphyses in pre-drilled holes orthogonal to the tibial axis. Implant and bone morphologies were investigated using μCT at 1, 3, and 6weeks after implant placement. At the same time points, the surrounding tissue was evaluated using H&E, TRAP and Goldner's trichrome staining. Although gas bubbles were observed around the degrading implant at early time points, the bone remained intact with no evidence of microfracture. Principle findings also include new bone formation in the area of the implant, suggesting that the alloy is a promising candidate for biodegradable orthopedic implants.

Microspheres as building blocks for hydroxyapatite/polylactide biodegradable composites

A new generation of organic/inorganic composites is offering a promising approach for creating biocompatible and biodegradable materials with mechanical properties that match that of human bone better than traditional metallic implants. Here, we report a novel technique whereby hydroxyapatite powder is encapsulated in polylactide-based microspheres, processed by an emulsion-solvent evaporation method, and then used as the building blocks to produce dense, microstructurally-uniform composites through a hot pressing route. The mechanical properties of these composites––both ab initio and after in vitro degradation in a simulated environment- were subsequently characterized. Although despite in vitro degradation remains an issue, the Young’s modulus, bending strength and fracture resistance were higher than the corresponding minimum values for human cortical bone. These results suggest that the hot-pressing of hydroxyapatite/polylactide microspheres can be a viable route for the synthesis of load-bearing bone-replacement materials.

Early findings in a pilot study of anterior cervical fusion in which bioabsorbable interbody spacers were used in the treatment of cervical degenerative disease.

In this pilot study the authors assessed the efficacy of bioabsorbable interbody spacers in the treatment of cervical degenerative disease. Metallic cages or interbody spacers have been widely used in the treatment of degenerative and traumatic cervical disease. Bioabsorbable technology has been used to develop a resorbable cage that can eliminate the complications and drawbacks seen with the use of traditional metallic implants. In general clinical practice bioabsorbable implants have shown the ability to degrade safely while demonstrating optimal imaging characteristics as a result of their radiolucency, and these devices eliminate stress shielding by their gradual dissolution. This study is a retrospective evaluation of charts and x-ray films obtained in the first eight patients who underwent an anterior cervical decompression and fusion procedure with placement of a bioabsorbable interbody spacer and anterior cervical plate. All patients were treated in one surgeon's practice and had a minimum follow-up period of at least 6 months. At a follow-up interval of approximately 7 months, five patients exhibited an excellent result and three had a good result; no patient was noted to have a satisfactory or poor outcome according to the Odom criteria at their most recent follow-up visit. Seventeen (94%) of 18 grafted levels appeared to be solidly fused. One patient experienced a perisurgical complication consisting of a symptomatic hematoma, which was successfully drained. Bioabsorbable interbody spacers appear to be a safe and effective interbody implant in terms of clinical outcome and radiographically confirmed healing.