Use Of Biodegradable Implants Research Articles

Microstructure, wear resistance, corrosion behavior, and cytotoxicity of Mg-Zn-Ca amorphous coatings fabricated by laser surface melting

To address the issues of rapid degradation rate in biodegradable magnesium alloys, which seriously restricts their clinical application, this study employed laser surface melting (LSM) on Mg-Zn-Ca alloys. The impact of the LSM process on the microstructural characteristics of magnesium alloy was examined. Subsequently, an assessment was conducted to analyze the hardness, corrosion resistance, friction and wear properties, as well as cytotoxicity of amorphous coatings applied on magnesium alloy for potential use in biodegradable implants. When the laser scanning power was set at 500 W and scanning speed was adjusted to 90 mm/s, the LSM alloy exhibited good comprehensive of properties, with a microhardness of 540 HV and a friction coefficient of 0.2024. Electrochemical analysis conducted in simulated body fluid (SBF) solution revealed that the LSM sample demonstrated favorable resistance to corrosion, as evidenced by a corrosion potential of -1.3346 V, corrosion current density of 0.0199 mA/cm2, and corrosion rate of 0.455 mm/y. Both the cast and LSM alloys exhibited non-toxicity towards SaOS2 cells, with the LSM alloys displaying slightly superior biocompatibility than the as-cast alloys.

Biodegradable Materials for Tissue Engineering: Development, Classification and Current Applications

The goal of this review is to map the current state of biodegradable materials that are used in tissue engineering for a variety of applications. At the beginning, the paper briefly identifies typical clinical indications in orthopedics for the use of biodegradable implants. Subsequently, the most frequent groups of biodegradable materials are identified, classified, and analyzed. To this end, a bibliometric analysis was applied to evaluate the evolution of the scientific literature in selected topics of the subject. The special focus of this study is on polymeric biodegradable materials that have been widely used for tissue engineering and regenerative medicine. Moreover, to outline current research trends and future research directions in this area, selected smart biodegradable materials are characterized, categorized, and discussed. Finally, pertinent conclusions regarding the applicability of biodegradable materials are drawn and recommendations for future research are suggested to drive this line of research forward.

Полимерные биодеградируемые фиксаторы в лечении около и внутрисуставных переломов

We have observed an increase in the number of patients with intra-articular fractures, as well as in the severity of such fractures. Traditionally, metal implants such as wires, capless screws, Herbert screws are used for osteosynthesis of intra-articular fractures with small bone and cartilage fragments. However, the metal implants have their drawbacks. Biodegradable fixatives (BDF) made from a copolymer of polylactic and polyglycolic acids (PLGA) could be an alternative to the implants. Two groups of 132 people with intra-articular fractures of different localization were formed, biodegradable implants were used in the main group, metal implants were used in the control group. The groups were correlated by sex, age and nature of fractures. We compared the time spent in the operating room for similar operations, the number of operations to remove the fixators in both groups, and the number of complications. Compared functional outcomes. We assessed the possibility of interpreting MSCT and MRI data in the isolated use of BDF. In the group with the use of biodegradable implants, fewer removal operations were required (44%) than in the group without the use of biodegradable implants (58%), which is statistically significant. Complications developed in the main group amounted to 3% (4 cases), while in the group with metal implants they amounted to 10% (13 cases). We have found that the use of biodegradable implants has satisfactory clinical results, a low percentage of implant removal operations, and lower complications rate.

Опыт применения биодеградируемых имплантов на основе магния при хирургическом лечении вальгусной деформации первого пальца стопы методикой mini-Scarf

The use of biodegradable implants is becoming increasingly popular, especially in operations on small bones of the skeleton, including operations on the anterior part of the foot. 23 surgical interventions were performed to correct the first metatarsal using the mini-Scarf technique and fixation of fragments with a biodegradable implant. All the operated patients did not have a severe radiological stage of osteoarthritis of the first metatarsophalangeal joint and stiffness. The results of treatment were evaluated using AOFAS and Groulier questionnaires. Out of 23 patients, it was possible to track and obtain data according to the questionnaires in 18 patients (78.3% (16 had grade III deformity (88.9%)). Six months after surgical treatment, the proportion of excellent and good results was 77.8% (14) according to the AOFAS questionnaire and 83.3% (15) according to the Groulier questionnaire. The achieved results suggest a favorable prognosis for the widespread use of magnesium oxide implants, however, further research and comparison of the results of treatment in patients with hallux valgus who underwent surgery with the use of standard titanium screws are needed.

Rationale for Processing of a Mg-Zn-Ca Alloy by Equal-Channel Angular Pressing for Use in Biodegradable Implants for Osteoreconstruction

Widespread use of Mg-Zn-Ca alloys in clinical orthopedic practice requires improvement of their mechanical properties—in particular, ductility—and enhancement of their bioactivity for accelerated osteoreconstruction. The alloy was studied in two structural states: after homogenization and after equal-channel angular pressing. Immersion and potentiodynamic polarization tests showed that the corrosion rate of the alloy was not increased by deformation. The mass loss in vivo was also statistically insignificant. Furthermore, it was found that deformation did not compromise the biocompatibility of the alloy and did not have any significant effect on cell adhesion and proliferation. However, an extract of the alloy promoted the alkaline phosphatase activity of human mesenchymal stromal cells, which indicates osteogenic stimulation of cells. The osteoinduction of the deformed alloy significantly exceeded that of the homogenized one. Based on the results of this work, it can be concluded that the alloy Mg-1%Zn-0.3%Ca modified by equal-channel angular pressing is a promising candidate for the manufacture of biodegradable orthopedic implants since it stimulates osteogenic differentiation and has greater ductility, which provides it with a competitive advantage in comparison with the homogenized state.

The First Experience of Dynamic Intramedullary Osteosynthesis of Diaphyseal Fractures of the Tibia Using Implants Based on Magnesium Alloy

Summary. The efficiency of using the dynamic blocking intramedullary osteosynthesis (BIOS) technique for tibial fractures with the use of biodegradable implants based on the MS-10 magnesium alloy was determined.
 Objective: to approve the technique and to study the effectiveness of dynamic intramedullary osteosynthesis of diaphyseal fractures of the tibia using locking screws made of the biodegradable magnesium alloy MS-10.
 Materials and Methods. The study was carried out in the Department of Traumatology of the Municipal Non-Profit Enterprise “City Hospital of Emergency and Ambulance” of Zaporizhzhia City Council in Zaporizhzhia on 15 patients with diaphyseal fractures of the tibia, who underwent BIOS. Cannulated intramedullary titanium rods were used as a fixator. In the proximal section, a screw made of titanium alloy was introduced into a dynamic hole; a screw made of a biodegradable magnesium alloy MC-10 was inserted into a static hole. In the postoperative period, the patients underwent a course of complex rehabilitation measures. X-ray control was performed on day 1, at week 4, week 8, and week 16 after the surgery.
 Results. After the start of the dosed load on the injured limb, a fracture of the locking screw made of MC-10 alloy was radiographically recorded in all patients. The dynamic screw moves in the dynamic hole and the fracture is dynamized. The formation of callus in the fracture zone was unremarkable and took an average physiological time. The quality and structure of callus did not show any pathological features. Four months after the surgery, all patients were socially adapted and did not use additional support when moving.
 Conclusions. Based on the data obtained, it is possible to draw a conclusion about the possibility and advisability of using biodegradable implants made of magnesium alloy MS-10 in a dynamic BIOS of long bones of the human skeleton.

Microstructure, mechanical and corrosion properties of Mg–Zn–Sr–Ca alloys for use as potential biodegradable implant materials

ABSTRACT Effects of Ca addition on as-cast microstructure, mechanical and corrosion properties of Mg–2Zn–0.3Sr alloy were investigated for biodegradable implant application. First, a comparison between Ca and Sr addition in Mg–2Zn alloy was studied. Mg–2Zn–0.3Sr showed the better corrosion performance, but the worse mechanical property. Then, the results of Ca addition indicated that the dendritic phases dispersed in the Mg matrix. The grains became smaller as Ca content increased. The ultimate tensile strength of Mg–2Zn–0.3Sr–0.3Ca alloy was strengthened to about 170MPa, along with a good ductility of 10%, due to the refinement of grains and homogenous morphology. The ternary alloy had the lowest degradation rate. Mg–2Zn–0.3Sr–0.3Ca still presented a considerable corrosion resistance. 0.5wt% Ca addition brought more and coarser second phases, and worse mechanical and corrosion property. It is suggested that minor addition of Ca (0.1–0.3wt%) in Mg–2Zn–0.3Sr alloy would benefit the practical performance for use in biodegradable implants.

Osteosynthesis of the Mandibular Condyle With Magnesium-Based Biodegradable Headless Compression Screws Show Good Clinical Results During a 1-Year Follow-Up Period

The use of titanium-based implants in mandibular condyle fractures can require implant removal because of screw penetration through the condylar surface. The use of biodegradable implants can avoid a second operation for implant removal and the associated possible complications. We investigated the clinical and radiologic outcomes of osteosynthesis of mandibular condyle fractures (MCFs) with biodegradable magnesium-based compression screws. We performed a retrospective observational study of 6 patients who had been treated at our department. We recorded the changes in jaw movements over time, occlusion, and possible complications at defined intervals of 1, 3, 6, and 12months postoperatively. We also compared the preoperative computed tomography (CT) scans with the postoperative cone-beam CT (CBCT) scans at 6 and 12months postoperatively to evaluate mandibular condyle healing and screw degradation. Of the 6 patients, 4 were men and 2 were women, with a mean age of 43.2years (range, 30 to 66years). All 6 patients had unilateral MCFs. All the patients showed well-restored function of the temporomandibular joint with significant improvement in mouth opening (46.17±6.49mm), right (10.67±1.03mm) and left (10.67±1.97mm) laterotrusion, and protrusion (10.17±1.33mm) distances to physiologic values. The CBCT scans showed the remodeling processes of the mandibular condyle and a few radiolucencies indicating the magnesium-based screws. Although penetration of 1 screw tip through the condylar surface had occurred, no implant removal was necessary owing to biodegradation of the implant. The results of the present study have shown that biodegradable magnesium-based compression screws provide good clinical results and avoid implant removal.

Degradation of biodegradable implants: The influence of microstructure and composition of Mg-Zn-Ca alloys

This work reports on the degradation of two (Zn-poor and Zn-rich) Mg-Zn-Ca crystalline alloys produced by mold casting yielding different kinds of microstructures with several scales. The dependence of corrosion properties and hydrogen evolution with alloy compositions, sizes and kinds of microstructure was exhaustively analyzed. The results were compared with amorphous alloys of same compositions. Zn-rich composition with average grain sizes of less than 500 nm presented marginal and an acceptable level of hydrogen, which was lower than for larger grains or Zn-poor composition. This behavior was explained by the reduction of the intrinsic metallic surface reactivity and the higher stability of the oxide film, which reduce the corrosion rate and, consequently, the hydrogen evolution. Mg-Zn-Ca crystalline alloys with Zn-alloying threshold and homogeneous grain size (<500 nm) appear hence to be of great potential for use in biodegradable implants.

THE USE OF BIODEGRADABLE IMPLANTS IN THE TREATMENT OF JUXTA- AND INTRAARTICULAR FRACTURES IN CHILDREN

Introduction. In the structure of the general morbidity rate, trauma and diseases of the musculoskeletal system take the third place after diseases of the respiratory system and pathology of the gastrointestinal tract. In recent years, an intensive indices characterizing the trauma prevalence rate has increased by 1.9 times. Aim. to improve the results of the management of juxta- and intraarticular fractures in children by means of the use of biodegradable implants. Material and methods. Over the period from 2014 to 2016 in the Department of Traumatology of the Research Institute of Emergency Pediatric Surgery and Traumatology there were examined and treated 108 children with juxta- and intra-articular fractures of the upper and lower extremities aged from 5 to 17 years, with an average age of 13.3 ± 1.8, including 38 (34.96 %) girls and 70 (65.04%) boys. All patients underwent complex examination including laboratory and instrumental methods: complete blood count (CBC), Common Urine Examination (CUE), X-Ray, spiral computed tomography, MRI. Results. To describe injuries and determine the tactics of the treatment of juxta- and intra-articular fractures in children, there was used the fracture classification system delivered by Robert B. Salter and W. Robert Harris. All children with metaphyseal fractures of the second, third, and fourth types underwent surgical treatment with the use of biodegradable implants. The postoperative period proceeded without complications. Conclusion. The use of biodegradable screws in juxta- and intra-articular fractures in children is a safe and effective method of treatment, reducing its timing by eliminating repeated surgical intervention.

Acceleration of the corrosion reaction of magnesium by Fenton reagents

Magnesium alloys have attracted increased attention for a variety of applications, chief among which are alternative energy and medical implants. The use of biodegradable implants in the complex system of the human body, in which myriad reactions occur, must consider the potential effects of the body’s natural chemical reactions on implant corrosion rates. The aim of this study was to elucidate the synergistic effects of pure Mg and Mg alloys on the Mg corrosion reaction with reagents that participate in the Fenton reaction. We corroborated our results with six different measurement methods (hydrogen evolution rate [HER], gas chromatography [GC], potentiodynamic polarization, inductively coupled plasma [ICP] spectrometry, Auger electron spectroscopy [AES], and scanning electron microscope [SEM]). The results point out that the corrosion and hydrogen evaluation rates of Mg were elevated by the addition of Fenton reagents, divalent iron and hydrogen peroxide, to a saline solution. In the context of Mg-based alloy medical implant development and use, this observation is significant.

Conductivity Sensor for Real‐time Monitoring of Magnesium Corrosion under Cell Culture Conditions

AbstractDue to its ability to biodegrade in an aqueous, chloride‐containing environment, magnesium (Mg) metal, pure or as an alloy, has attracted significant interest in biomaterials research for use in biodegradable implants for bone repair and other applications. However, the interactions between Mg metal and surrounding cells and tissues as the metal resorbs need to be studied extensively to ensure adequate biocompatibility for each intended application. Cell death can result from high local concentrations of the soluble resorption products, which include Mg ions (Mg2+), alloying products, increased pH and hydrogen. Because these products are primarily ionic, we tested whether a conductivity sensor could be used to monitor Mg degradation by detecting changes in ionic strength in real time, in three physiologically appropriate fluids (a sodium chloride solution, phosphate buffered saline and a cell culture medium maintained under the standard conditions used for mammalian cell culture). Here we demonstrate that an electrochemical conductivity sensor, in combination with a pH sensor, recorded very different patterns of real‐time changes in the ionic environment created by Mg immersion and degradation in the three model electrolyte solutions, over a 48‐hour time period.

Accelerated Degradation Behavior and Cytocompatibility of Pure Iron Treated with Sandblasting.

Fe-based materials are of interest for use in biodegradable implants. However, their corrosion rate in the biological environment may be too slow for the targeted applications. In this work, sandblasting is applied as a successful surface treatment for increasing the degradation rate of pure iron in simulated body fluid. Two sandblasting surfaces with different roughness present various surface morphologies but similar degradation products. Electrochemistry tests revealed that sandblasted samples have a higher corrosion rate compared to that of bare iron, and even more noteworthy, the degradation rate of sandblasted samples remains significantly higher during long-term immersion tests. On the basis of our experimental results, the most plausible reasons behind the fast degradation rate are the special properties of sandblasted surfaces, including the change of surface composition (for the early stage), high roughness (occluded surface sites), and high density of dislocations. Furthermore, the cytocompatibility was studied on sandblasting surfaces using human osteoblast-like cells (MG-63) by indirect and direct contact methods. Results revealed that sandblasting treatment brings no adverse effect to the growth of MG-63 cells. This work demonstrates the significant potential of sandblasting for controlling the degradation behavior of iron-based materials for biomedical applications.

Improvement of corrosion resistance of magnesium alloys for biomedical applications

AbstractIn recent years, magnesium (Mg) alloys have attracted great attention due to superior biocompatibility, biodegradability, and other characteristics important for use in biodegradable implants. However, the development of Mg alloys for clinical application continues to be hindered by high corrosion rates and localized corrosion modes, both of which are detrimental to the mechanical integrity of a load-bearing temporary implant. To overcome these challenges, technologies have been developed to improve the corrosion resistance of Mg alloys, among which surface treatment is the most common way to enhance not only the corrosion resistance, but also the bioactivity of biodegradable Mg alloys. Nevertheless, surface treatments are unable to fundamentally solve the problems of fast corrosion rate and localized corrosion. Therefore, it is of great importance to alter and improve the intrinsic corrosion behavior of Mg alloys for biomedical applications. To show the significance of the intrinsic corrosion resistance of biodegradable Mg alloys and attract much attention on this issue, this article presents a review of the improvements made to enhance intrinsic corrosion resistance of Mg alloys in recent years through the design and preparation of the Mg alloys, including purifying, alloying, grain refinement, and heat treatment techniques. The influence of long-period stacking-ordered structure on corrosion behavior of the biodegradable Mg alloys is also discussed.

Influence of Nd in Extruded Mg10Gd Base Alloys on Fatigue Strength

Magnesium alloys containing Rare Earth elements have proven to be suitable candidates for uses at high temperatures due to their good creep resistance as well as for use in biodegradable implants due to their adequate corrosion rate and biocompatibility. This work investigates the fatigue strength and cyclic deformation behavior of an extruded Mg10Gd1Nd in comparison to Mg10Gd and possible benchmark alloys WE43 and AZ31. The influence of the alloying element Nd is remarkable. The finite life fatigue strengths of Mg10Gd1Nd in the SN-diagram (Wöhler curve) are strongly improved compared to Mg10Gd and almost reach the strength values of WE43. Fracture surface morphology and crack propagation are discussed with attention given to low and high cycle fatigue. The very fine grain size, as the result of dynamic recrystallization during extrusion, offers high elongation at fracture. Therefore the residual fracture surface, where rapid failure occurs, is rather small in the high cycle fatigue samples. The size of the slow crack growth area has been determined by the appearance of benchmark ridges and fatigue striations and is discussed in correlation to stress and number of cycles. Scatter behavior of fatigue life was investigated by optical microcopy. The microstructure consists of second phase alignments in the extrusion direction, which differs in length, precipitate size and distance. Crack branching appears depending on microstructure and the load applied.

The Effect of Mg Supplement on Hydroxyapatite Produced by Chemical Precipitation

Hydroxyapatite (HAp) exhibits excellent biocompatibility but the low mechanical strength of normal HAp ceramics generally restricts its use to low load-bearing applications. Magnesium is an attractive material for use in biodegradable implants due to its low density, non-toxicity and mechanical properties similar to those of human tissue such as bone. Its biocompatibility makes it amenable for use in a wide range of applications from bone to cardiovascular implants. The aim of this work was to produce hydroxyapatite powder with chemical precipitation method and supplement Mg and investigate the e ect of magnesium on structure of HAp powders. The Mg content ranged between 1 and 2 mol.%. The Mg+HAp powders were examined for morphology. The scanning electron microscopy, X-ray di raction, energy-dispersive X-ray spectroscopy were used to characterize the specimen powders.

Versorgung von dislozierten Radiuskopffrakturen mit bioresorbierbaren Implantaten

The Mason classification is used for radial head fractures. Mason type I fractures are managed by a functional conservative treatment of no loading for six weeks. Mason II fractures with a displacement greater than 10° or a depression of greater than 2 millimeters are treated with open reduction and use of biodegradable implants constructed of polylactide. These implants have the advantage of maintaining the joint surface by placement beneath the surface of the articular cartilage. Furthermore, the implants can be placed from various positions through the articular surface and are therefore more versatile than other modes of open reduction. The OP technique in Mason II radial head fracture is demonstrated in a video for the example of a 31-year-old male patient. 35 patients were treated using the new polylactide pins (Polypin®). Average follow-up for 34 patients was 38 months. 31 patients with Mason type II fractures presented with a score of 96 out of 100 using the Broberg Morrey score. CT scans were performed after 18 and 24 months in all patients. One first degree asymptomatic osteolysis was observed at 18 months which was reduced at 24 months. Two years later the pins were not visible on conventional X-rays. CT scans at 5 years revealed the implants to be in various levels of resorption and bony regrowth. Dislocated radial head fractures can be treated with good results with biodegradable implants.

Hardness enhancement of PEO-treated Mg alloy for biodegradable implants

In recent times, magnesium alloys have emerged as a possible biodegradable implant material. Plasma electrolytic oxidation (PEO) has been used in the past as a useful surface treatment technique to improve wear resistance and corrosion resistance of magnesium alloys by forming protective coatings. This study focuses on the effect of electrolyte solution on the microstructural and nanomechanical behavior of PEO coatings for possible use in biodegradable implants. Microstructural characterization of the coating was carried out by X-ray diffraction (XRD), scanning electron microscopy followed by image analysis and energy dispersive X-ray spectroscopy. Furthermore, nanoindentation was used to evaluate nanohardness of the PEO coatings. The results show beneficial effects of the PEO coating to improve the hardness of the uncoated AZ31 magnesium alloy. The XRD pattern shows that the crystal structures of the film vary based on electrolyte solution and the effect that has on nanomechanical behavior. In conclusion, this article shows the possible benefit of PEO coating for biodegradable implant use.

Outcomes of Operative Treatment of Unstable Ankle Fractures: A Comparison of Metallic and Biodegradable Implants

Biodegradable implants for internal fixation of ankle fractures may overcome some disadvantages of metallic implants, such as imaging interference and the potential need for additional surgery to remove the implants. The purpose of this study was to evaluate the outcomes after fixation of ankle fractures with biodegradable implants compared with metallic implants. In this prospectively randomized study, 109 subjects with an ankle fracture underwent surgery with metallic (Group I) or biodegradable implants (Group II). Radiographic results were assessed by the criteria of the Klossner classification system and time to bone union. Clinical results were assessed with use of the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale, Short Musculoskeletal Function Assessment (SMFA) dysfunction index, and the SMFA bother index at three, six, and twelve months after surgery. One hundred and two subjects completed the study. At a mean of 19.7 months, there were no differences in reduction quality between the groups. The mean operative time was 30.2 minutes in Group I and 56.4 minutes in Group II (p < 0.001). The mean time to bone union was 15.8 weeks in Group I and 17.6 weeks in Group II (p = 0.002). The mean AOFAS score was 87.5 points in Group I and 84.3 points in Group II at twelve months after surgery (p = 0.004). The mean SMFA dysfunction index was 8.7 points in Group I and 10.5 points in Group II at twelve months after surgery (p = 0.060). The mean SMFA bother index averaged 3.3 points in Group I and 4.6 points in Group II at twelve months after surgery (p = 0.052). No difference existed between the groups with regard to clinical outcomes for the subjects with an isolated lateral malleolar fracture. The outcomes after fixation of bimalleolar ankle fractures with biodegradable implants were inferior to those after fixation with metallic implants in terms of the score on the AOFAS scale and time to bone union. However, the difference in the final AOFAS score between the groups may not be clinically important. The outcomes associated with the use of biodegradable implants for the fixation of isolated lateral malleolar fractures were comparable with those for metallic implants.

Biocompatibility and biodegradability of Mg–Sr alloys: The formation of Sr-substituted hydroxyapatite

Magnesium is an attractive material for use in biodegradable implants due to its low density, non-toxicity and mechanical properties similar to those of human tissue such as bone. Its biocompatibility makes it amenable for use in a wide range of applications from bone to cardiovascular implants. Here we investigated the corrosion rate in simulated body fluid (SBF) of a series of Mg–Sr alloys, with Sr in the range of 0.3–2.5%, and found that the Mg–0.5 Sr alloy showed the slowest corrosion rate. The degradation rate from this alloy indicated that the daily Sr intake from a typical stent would be 0.01–0.02mgday−1, which is well below the maximum daily Sr intake levels of 4mgday−1. Indirect cytotoxicity assays using human umbilical vascular endothelial cells indicated that Mg–0.5 Sr extraction medium did not cause any toxicity or detrimental effect on the viability of the cells. Finally, a tubular Mg–0.5 Sr stent sample, along with a WE43 control stent, was implanted into the right and left dog femoral artery. No thrombosis effect was observed in the Mg–0.5 Sr stent after 3weeks of implantation while the WE43 stent thrombosed. X-ray diffraction demonstrated the formation of hydroxyapatite and Mg(OH)2 as a result of the degradation of Mg–0.5 Sr alloy after 3days in SBF. X-ray photoelectron spectroscopy further showed the possibility of the formation of a hydroxyapatite Sr-substituted layer that presents as a thin layer at the interface between the Mg–0.5 Sr alloy and the corrosion products. We believe that this interfacial layer stabilizes the surface of the Mg–0.5 Sr alloy, and slows down its degradation rate over time.