Osteosynthesis Devices Research Articles

Российский рынок имплантов для остеосинтеза

Analysis of the Russian implants market has been conducted based on data on public procurement of osteosynthesis devices, and the export-import transaction database of the official customs statistics. In the article, the term «osteosynthesis devices» is used to indicate the medical devices of this type. The purchase of such devices is most important to meet the needs of the public health system. The total consumption of osteosynthesis implants in value terms amounted to about RUB 4.530 bil. in 2018. In general, the consumption has shown positive dynamics, since 2015. The increase in purchases accounted for more than 66% in 2018 compared to 2015. The analysis of the osteosynthesis implants consumption pattern based on the results for 2018 showed that the main share was accounted for by bone implants - 43.40%. The manufacturers of the Asian group - 33% and Locals - 24% demonstrated outperforming growth rates (exceeding the general dynamics of consumption in value terms) over the period from 2015 to 2018. The increase in the supplies of EU&US group manufacturers by 12% is below the market average figures. The analysis of osteosynthesis implant supplies pattern of the regional groups based on the results for 2018 showed that the main share is accounted for by the products from the leading world and European brands - 44.20% or RUB 2.002 bil. A significant share in the total supplies is accounted for by the implants of the Russian manufacturers - 35.26% or RUB 1.597 bil. The leading brands face stiff competition from the local companies in the osteosynthesis implants market.

Osteoporotic distal femur fractures in the elderly: peculiarities and treatment strategies.

Distal femur fractures account for 4-6% of osteoporosis related fractures of the femur in the elderly population. They represent a relevant cause of morbidity and mortality in the geriatric population with a reported 1-year mortality reaching 30%. Non-displaced fractures or even displaced fractures in patients with high operative risk can be treated conservatively. However, operative treatment is the most widely accepted management option for displaced fractures. The advantage resides in early mobilization and weight-bearing, reducing risks related with a prolonged immobilization when compared with conservative treatment. On the other hand, the intrinsic difficulty of fixing an osteoporotic bone is a major concern. The presence of osteosynthesis devices or prosthetic implants in the femur can make the surgical treatment more challenging, sometimes limiting therapeutic options. Aim of the present paper is to review the most recent literature about osteoporotic distal femur fractures in the elderly, including periprosthetic and other hardware related fractures, to highlight current evidence on management options and related results as a guide for the daily clinical practice. (www.actabiomedica.it)

Plasma poly(acrylic acid) compatibilized hydroxyapatite-polylactide biocomposites for their use as body-absorbable osteosynthesis devices

The nanoscale interface between hydroxyapatite (HA) particles and PLLA matrix appears to be the determining factor for poor mechanical performance of this family of biocomposites in load-bearing applications. It has been demonstrated that when these biocomposites are loaded, the physical adsorption between inorganic particles and polymeric matrix does not allow for load transfer and additional free surfaces that act as crack nucleators are created. To overcome this limitation, we propose plasma polymerization of poly (acrylic acid) (PAA) on HA particles as an effective method to produce strong interactions with the polylactide (PLLA) matrix. In this work, evidences of an intimate bonding between HAPAA particles and PLLA are given. Based on the thermodegradation behaviour of the composites it was found that the plasma deposited layer arrested free hydroxyl groups of PLLA chains, hindering the transesterification reactions that cause the thermal degradation of PLLA. As a result, thermal degradation of the composites was retarded and followed the chain scission route producing acetaldehyde, CO and CO2. From the mechanical characterization it became clear that load transfer was developed by means of the PAA compatibilized interface resulting in the observed enhancement of the elasticity and damping behaviour of the biocomposites.

Sternal semi-closure using a bioresorbable osteosynthesis device: a new method for delayed sternal closure.

To evaluate the safety and efficacy of our new delayed sternal closure (DSC) method, involving sternal semi-closure using a bioresorbable osteosynthesis device and complete skin closure. Between 2013 and 2017, 36 patients underwent DCS at our hospital. The patients were divided into two groups based on the method used for DSC. The later conventional DSC group consisted of 18 patients undergoing late complete sternal closure following fixation of pulmonary and hemodynamic instability, and the new DSC group consisted of 18 patients undergoing early sternal semi-closure a few days after surgery. In the new DSC group, the sternum was fixed with Super Fixsorb MX40, followed by complete skin closure. Respiratory and hemodynamic conditions, such as systolic blood pressure, cardiac index, tidal volume, and regional oxygen saturation, were significantly more stable in the new DCS group than in the conventional DSC group. The hospital stay was also significantly shorter in the new DSC group. Although there were no serious complications, one patient from the new DCS group suffered deformity of the sternum, which was managed successfully. The sternal semi-closure method decreases pulmonary and cardiac instability during DSC, making early DSC possible.

Complications of Bone Plating Following Different Facial Bones Fractures

The Aim of our study was to evaluate the complication of bone plating fixation used for treatment of multiple type of facial fracture, reconstruction procedure and bone graft in maxillofacial trauma. This prospective study was performed on 42 patients to evaluates complications of the bone plates had been used in fixation of multiple facial fractures, between October 2013 and March 2015, The age of the patients ranged from 17 – 65 years The mean age of the patients was (31.7± 9.4) years. There were 31 males and 11 females, with male to female ratio (2.81:1), patients were followed up for minimum 6 months. Seventy-one plates were inserted over 17 months. Among the 42 patients there were 45 fracture sites, 26 (57.8%) were mandibular fractures, 15 (33.3%) were ZMC fractures, and four (8.9%) were maxillary; it is worth mentioning that some patients had fracture at more than one site. Complications due to fracture fixation with bone plating were 33 represented 46.5% of the total 71 plates inserted, which included Infection/wound dehiscence 15 (21.1%), Discomfort/ palpability 9 (12.7%), Plate exposure 4 (5.6%), hardware failure (broken plate & loosening screw) 1 (1.4%), Cold/heat intolerance 3 (4.2%) and Pain (TMJ) account for one plate (1.4%). According to this study, there will be a need for hardware removal in a portion of patients treated with metallic osteosynthesis devices. This study states that the infection is most common reason for plate removal, followed by discomfort due to cold/heat climate, particularly in those facial regions that provide only thin soft tissue cover over the plate.

High strength, biodegradable and cytocompatible alpha tricalcium phosphate-iron composites for temporal reduction of bone fractures

In this work alpha tricalcium phosphate (α-TCP)/iron (Fe) composites were developed as a new family of biodegradable, load-bearing and cytocompatible materials. The composites with composition from pure ceramic to pure metallic samples were consolidated by pulsed electric current assisted sintering to minimise processing time and temperature while improving their mechanical performance. The mechanical strength of the composites was increased and controlled with the Fe content, passing from brittle to ductile failure. In particular, the addition of 25 vol% of Fe produced a ceramic matrix composite with elastic modulus much closer to cortical bone than that of titanium or biodegradable magnesium alloys and specific compressive strength above that of stainless steel, chromium-cobalt alloys and pure titanium, currently used in clinic for internal fracture fixation. All the composites studied exhibited higher degradation rate than their individual components, presenting values around 200 μm/year, but also their compressive strength did not show a significant reduction in the period required for bone fracture consolidation. Composites showed preferential degradation of α-TCP areas rather than β-TCP areas, suggesting that α-TCP can produce composites with higher degradation rate. The composites were cytocompatible both in indirect and direct contact with bone cells. Osteoblast-like cells attached and spread on the surface of the composites, presenting proliferation rate similar to cells on tissue culture-grade polystyrene and they showed alkaline phosphatase activity. Therefore, this new family of composites is a potential alternative to produce implants for temporal reduction of bone fractures. Statement of SignificanceBiodegradable alpha-tricalcium phosphate/iron (α-TCP/Fe) composites are promising candidates for the fabrication of temporal osteosynthesis devices. Similar to biodegradable metals, these composites can avoid implant removal after bone fracture healing, particularly in young patients. In this work, α-TCP/Fe composites are studied for the first time in a wide range of compositions, showing not only higher degradation rate in vitro than pure components, but also good cytocompatibility and mechanical properties controllable with the Fe content. Ceramic matrix composites show high specific strength and low elastic modulus, thus better fulfilling the requirements for bone fractures fixation. A significant advance over previous works on the topic is the use of pulsed electric current assisted sintering together with α-TCP, convenient to improve the mechanical performance and degradation rate, respectively.

Complications of a poly-L-lactic acid and polyglycolic acid osteosynthesis device for internal fixation in maxillofacial surgery.

The purpose of this study was to retrospectively evaluate and examine the incidence of complications using poly-L-lactic acid and polyglycolic acid (PLLA/PGA) copolymer plate system in maxillofacial osteosynthesis. The retrospective study included 87 patients (50 men, 37 women), who needed maxillofacial surgery. We examined the proportion of complications and their factors from clinical data. A comparison was also made for plate decomposition using the molecular weight of the plate without plate exposure and complications. Osteosynthesis sites healed in all patients. Ten cases (11.5%) showed plate exposure-related complications, with all occurring at intraoral surgical sites. There was no significant difference in molecular weight changes of plates in resorbable process. Statistical analysis of study variables between patients with and without exposed plates showed that the plate thickness was significantly associated with the risk of exposed plates (p<0.05). The commercially available PLLA/PGA device could be a useful rapid resorbable material for maxillofacial osteosynthesis. When thick plates are used on the intraoral site, it may be necessary to pay attention to the complication of plate exposure. Even if exposure-related complications have occurred, resorption and degradation of this material proceeds, suggesting the ease of appropriate risk management.

Comparative Evaluation of Clinical Outcomes Using Delta Plates and Conventional Miniplates for Internal Fixation of Mandibular Condylar Fractures in Adults

In recent years numerous osteosynthesis devices have become available for the management of condylar fractures. The aim of this study was to compare and evaluate the clinical outcomes of delta plates and conventional miniplates for internal fixation of mandibular condylar fractures in adults. We performed a prospective study of 20 patients with subcondylar fractures requiring open reduction and internal fixation for their management. Patients were randomly divided into 2 groups using computer software: Group A patients (n=10) were treated using delta plates whereas group B patients (n=10) were treated using conventional miniplates via an extraoral retromandibular transparotid approach. There was no statistically significant difference between delta plates and conventional miniplates for internal fixation of mandibular condylar fractures in adults. However, the time taken for adaptation of the delta plates was significantly lower than that required for the 2 miniplates (P<.001), and the ease of adaptation was significantly better for the delta plates (P<.001). The study results indicated that the delta plate and miniplate are equally effective in terms of long-term clinical success in the management of mandibular subcondylar fractures in adults. The delta plate is superior in terms of handling characteristics, such as ease of adaptation and time required for adaptation, as only 1 plate and 4 screws are required as compared with 2 plates and 8 screws.

Biocompatibility and degradation properties of WE43 Mg alloys with and without heat treatment: In vivo evaluation and comparison in a cranial bone sheep model

PurposeOrthopedic and maxillofacial bone fractures are routinely treated by titanium internal fixation, which may be prone to exposure, infection or intolerance. Magnesium (Mg) and its alloys represent promising alternatives to produce biodegradable osteosynthesis devices, with biocompatibility and, specifically, hydrogen gas production during the degradation process, being the main drawback. Aim of this study is to test and compare biocompatibility, degradation rate and physiscochemical properties of two Mg-alloys to identify which one possesses the most suitable characteristics to be used as resorbable hardware in load-bearing fracture sites. Materials and methodsAs-cast (WE43) and T5 Mg-alloys were tested for biocompatibility, physical, mechanical and degradation properties. Microstructure was assessed by optical microscopy, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS); mechanical properties were tested utilizing quasi-static compression and failure analysis. Locoregional biocompatibility was tested by sub-periosteal implantation on the fronto-nasal region of large-animal model (sheep): regional immunoreaction and metal accumulation was analyzed by LA-ICP of tributary lymph-nodes, local reactions were analyzed through histological preparation including bone, implant and surrounding soft tissue. ResultsMechanically, T5 alloy showed improvement in strength compared to the as-cast. Lymph-node Mg accumulation depicted no differences between control (no implant) and study animals. Both alloys showed good biocompatibility and osteogenesis-promoting properties. ConclusionThis study demonstrated excellent biocompatibility and osteogenesis-promoting capabilities of the tested alloys, providing a platform for further studies to test them in a maxillofacial fracture setting. T-5 alloy displayed more stability and decreased degradation rate than the as-cast.

Osteosynthesis of a cranio-osteoplasty with a biodegradable magnesium plate system in miniature pigs.

To the best of our knowledge this is the first study that used biodegradable magnesium implants for osteosynthesis in a cranial fracture model. The cranio-osteoplasty in miniature pigs allowed in vivo application of plate and screw osteosynthesis of standard-sized implants and the implementation of surgical procedures similar to those conducted on human beings. The osteosynthesis configuration, size, and mechanical properties of the magnesium implants within this study were comparable to those of titanium-based osteosynthesis materials. The results clearly show that bone healing was undisturbed in all cases and that the biocompatibility to hard- and soft tissue was sufficient. Magnesium implants might help to avoid long-term complications and secondary removal procedures due to their biodegradable properties.

EIS, Mott Schottky and EFM analysis of the electrochemical stability and dielectric properties of Ca-P-Ag and Ca-P-Si-Ag coatings obtained by plasma electrolytic oxidation in Ti6Al4V

Ti6Al4V ELI (ASTM F136) alloy is one of the most used alloys in devices forosteosynthesis and joint replacement. However, the properties of this alloy can be improvedregarding biocompatibility and the osteointegration with the bone tissue through coatings.The aim of this study was the evaluation of the electrochemical behavior of a coating obtainedby plasma electrolytic oxidation on Ti6Al4V ELI, using electrolyte solutions enriched withPO42-, Ca+2, Si+4 ions and various concentrations of Ag+1. The coatings were characterized byelectrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) in a three-electrodecell with a simulated physiological solution. The electrochemical behavior was comparedwith electrostatic force microscopy (EFM). The EIS results showed improved stabilityproperties in corrosion for Ca-P-Ag coatings, compared with Ca-P-Si-Ag. Nyquist and BodeSpectra showed relaxations related to charge transference to the double electrochemicallayer and the reflex of the microstructural changes and conductivity of the coating given byits composition. According to with M-S results, all the samples showed an n-type conductivityincreased with silver inclusion. The potential, the phase, and amplitude of the coatings withsilver inclusion compared to uncoated Ti6Al4V were observed by EFM.

Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies.

Rat models are widely used in preclinical studies investigating fracture healing. The interfragmentary movement at a fracture site is critical to the course of healing and therefore demands definition in order to aptly interpret the experimental results. Estimation of this movement requires knowledge of the fixation stiffness and loading. The characteristic loading for the rat femur has been estimated, but the stiffness of fixation used in rat studies has yet to be fully described. This study aimed to determine the 6 degree of freedom stiffness of four commonly used implants, two external fixators (RatExFix and UlmExFix), a locking plate, and a locking intramedullary nail, in all degrees of freedom and estimate the interfragmentary movement under specific physiological loads. The external fixator systems allow the greatest movement. Mounted 45° anterolateral on the femur, the RatExFix allows an average of 0.88 mm of motion in each anatomic direction while the stiffer UlmExFix allows about 0.6 mm of motion. The nail is far stiffer than the other implants investigated while the plate allows movement of an intermediate magnitude. Both the nail and plate demonstrate higher axial than shear stiffness. The relatively large standard deviations in external fixator shear motion imply strong dependence on bone axis alignment across the gap and the precise orientation of the specimen relative to the loading. The smaller standard deviation associated with the nail and plate results from improved alignment and minimization of the influence of rotational positioning of the specimen due to the reduced implant eccentricity relative to the specimen axis. These results show that the interfragmentary movement is complex and varies significantly between fixation devices but establishes a baseline for the evaluation of the results of different studies.

Antibacterial effect of novel biodegradable and bioresorbable PLDA/Mg composites

Polylactic acid/Mg composites have been recently proposed for biodegradable osteosynthesis devices because, with regards to the neat polymer, they combine an enhanced biocompatibility and bioactivity with better mechanical properties, particularly creep strength. A question still arises about their bacterial behavior. For this purpose, composites of poly-L-D-lactic acid (PLDA) loaded with 1 and 10 wt.% of Mg microparticles were evaluated using Staphylococcus epidermidis, with special emphasis on the study of bacterial adhesion and biofilm formation. During biofilm formation the bacteria viability of the composites decreased up to 65.3% with respect to PLDA. These antibacterial properties do not compromise the cytocompatibility of the material as the composites enhanced the viability of mesenchymal stem cells and their osteogenic commitment. These findings provide an important added value to the biodegradable and biocompatible PLDA/Mg composites for the manufacture of osteosynthesis devices.

COMPARATIVE STUDY BETWEEN TWO DIFFERENT OSTEOSYNTHESIS DEVICES FOR FIXATION OF SUBCONDYLAR FRACTURE

Statement of problem: Management of subcondylar fracture with proper reduction of temporomandibular joint position and function is a challenge, different osteosynthesis devices are used with great diversity in their types, numbers, positions, and results.Purpose: Comparative study between the efficiency of single miniplate and single minidynamic compression plate in restoration of ramus height, condylar angulation, and tempromandibular joint function in subcondylar fracture cases.Material and Method: 14 patients indicated for open reduction and fixation of subcondylar fractures were divided into two groups each of 7 patients. Group A: subcondylar fractures were fixed using 2.0 single miniplate along posterior border of ramus. Group B: a single 2.0-mm minidynamic compression plates (DCP), were applied along posterior border of ascending ramus for fracture fixation in the other seven patients. Intermaxillary fixation for 10 days was applied for both groups. Clinical and radiograhic follow up were performed at 1, 3, 6 months using panorama and CT. Results: At 6 months postoperatively, there was an improvement of mandibular functions with improvement of inter-incisal opening from 19.1mm and 20.1 mm in group A and B respectively to 35.6mm and 30.8 mm. Which was significantly different (P value =0.04). The shortening in ramus height improved from 3.2mm and 5.2mm in group A and B to 0.8 mm and 0.6 mm, also sagittal angulation of condyle improved from 1.6o and 4.7o in both group respectively to 0.2o and 0.3o with no significant difference between two types of mini-plate. There were no signs of infection, malunion, nonunion or device failure in both groups. except for one case of group A, that suffered from malocclusion with displacements of the fractured segments immediately after the operations, that responded to elastic traction within 15 days.Conclusion: Single 0.2 mm miniplate or mini DCP aided by intermaxillary fixation are successful devices in fixation of subcondylar fracture without complication, with superiority of mini DCP in proper condylar reduction and stable fixation.

Contralateral Prophylactic Reinforcement in Case of First Low-Energy Hip Fracture: First-in-Man Clinical Data of a New Percutaneous Internal Fixation Device

A prevention dedicated osteosynthesis device (Y-STRUT®, Hyprevention) was developed to reinforce the proximal femur on patients with high risk of fragility hip fracture. A multicentre pilot study was initiated to evaluate the feasibility, safety and tolerance of this device and the related operative procedure. This clinical study is an on-going prospective series of 15 patients. Between February 2013 and December 2016, 10 patients were implanted. Patients were recruited when arriving to emergencies following a low-energy trauma leading to a pertrochanteric hip fracture. The device was implanted in combination with bone cement into the contralateral hip during the same anaesthesia as the fractured hip fixation. Clinical evaluation includes pain evaluation, functional status, and osteointegration of the device. Mean age of patients was 82 ± 7 years. Mean duration of implantation was 56 ± 19 min for Y-STRUT® implantation and 37 ± 24 for fracture fixation in the opposite side. Mean cement quantity injected was 8 ± 1.6 ml. At 3 months, WOMAC scores for pain and functionality were 5 and 24, respectively and 4 and 18 at 12 months. Mean follow-up is 16 ± 12 months. No patient died during the follow-up. No osteolysis nor post-operative fracture were observed. Preliminary results of this prospective study showed the feasibility, safety and tolerance of the implantation of this new device. Further patients are required to confirm this experience and confirm efficacy of the device to reduce the risk of contralateral hip fracture during the first year after the first fracture when elderly patients are at the highest risk of fracture and mortality and the anti-osteoporosis medication prescribed at fracture is not yet efficient.

In Vivo Evaluation of Bulk Metallic Glasses for Osteosynthesis Devices.

Bulk metallic glasses (BMGs) show higher strength and lower Young’s modulus than Ti-6Al-4V alloy and SUS 316L stainless steel. This study aimed to perform in vivo evaluations of Zr65Al7.5Ni10Cu17.5 BMGs for osteosynthesis devices. In the study for intramedullary implants, osteotomies of the femoral bones were performed in male Wistar rats and were stabilized with Zr65Al7.5Ni10Cu17.5 BMGs, Ti-6Al-4V alloy, or 316L stainless steel intramedullary nails for 12 weeks. In the study for bone surface implants, Zr65Al7.5Ni10Cu17.5 BMGs ribbons were implanted on the femur surface for 6 weeks. Local effects on the surrounding soft tissues of the implanted BMGs were assessed by histological observation. Implanted materials’ surfaces were examined using scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS). In the study for intramedullary implants, bone healing after osteotomy was assessed by peripheral quantitative computed tomography (QCT) and mechanical tests. Histological observation showed no findings of the biological effects. SEM-EDS showed no noticeable change on the surface of BMGs, while Ca and P deposition was seen on the Ti-6Al-4V alloy surface, and irregularities were seen on the 316L stainless steel surface. Mechanical test and peripheral QCT showed that, although there was no significant difference, bone healing of BMGs was more than that of Ti-6Al-4V alloy. The results indicated that Zr-based BMGs can lead to bone healing equal to or greater than Ti-6Al-4V alloy. Zr-based BMGs exhibited the advantage of less bone bonding and easier implant removal compared with Ti-6Al-4V alloy. In conclusion, Zr-based BMGs are promising for osteosynthesis devices that are eventually removed.

Clinical features and outcome of bone and joint infections with streptococcal involvement: 5-year experience of interregional reference centres in the south of France.

Streptococcal bone and joint infections are less common than staphylococcal cases. Few studies have reported the cases with well-identified Streptococcus species. Their clinical features and prognosis are not clearly known to date. Moreover, no treatment regimen has yet been clarified. We reviewed the streptococcal bone and joint infection cases managed in our centres from January 2009 to December 2013. We described the epidemiology, clinical and microbiologic characteristics, treatment approach and outcome. Among the 93 cases, 83% of patients were men with a median age of 60 years, and 90% of patients had comorbidities or risk factors. Bacteraemia occurred in 14% of cases. Serious complications occurred in six patients, including severe sepsis (two cases) and infective endocarditis (two cases). Orthopaedic device infections were observed in 35% of cases, including 17 patients with internal osteosynthesis device infection, 14 with prosthetic joint infection and three with vertebral osteosynthesis device infection. The median time between orthopaedic device implantation and onset of infection was 447 days. Fourteen species of Streptococcus were identified, including 97 isolates using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and three isolates using molecular identification. The five most represented species included S. agalactiae (37%), S. dysgalactiae (12%), S. anginosus (11%), S. constellatus (10%) and S. pneumoniae (9%). Streptococci isolates were susceptible to amoxicillin, with the exception of one S. mitis isolate. Remission 1 year after the end of treatment was recorded in 83%. One patient died of infection; eight patients had infections that failed to respond to treatment; and seven patients experienced relapse. Twenty patients (22%) had an unfavourable functional outcome, including 19 amputations and one arthrodesis. Five significant prognostic factors associated with an unfavourable clinical outcome were identified, including peripheral neuropathy (p 0.009), peripheral arterial disease (p 0.019), diabetes mellitus (p 0.031), location in the femur (p 0.0036), location in the foot (p 0.0475), osteitis without an orthopaedic device (p 0.041) and infection caused by S. dysgalactiae (p 0.020). The rate of poor outcomes remains high despite the low number of Streptococcus isolates resistant to antibiotics. Some prognostic factors, such as the presence of S. dysgalactiae, are associated with an unfavourable clinical outcome. Antibiotic regimens of streptococcal bone and joint infections are not standardized and need to be further investigated.

THE RESULTS OF CLINICAL APPLICATION OF THE SPRING-LOADED FIXATOR IN OSTEOSYNTHESIS OF THE MEDIAL FRACTURES OF FEMORAL NECK

The share of femoral neck fractures in the structure of injuries enlarges every year due to increasing number of elderly people. Known techniques of osteosynthesis do not provide satisfactory results of treatment in the majority of patients with medial femoral neck fractures. The goal: to improve outcomes of treatment for the patients with medial femoral neck fractures through the development and introduction into clinical practice a new method of bone fragments connecting. The methods: a new device for osteosynthesis of medial femoral neck fractures was worked out and implemented into clinical practice; due to its design features this device can provide primary intertrfragmental compression during surgery and secondary due to potential energy of the compressed spring. A special mechanism of ratchet gearing provides unidirectional telescopic effect and prevents the formation of interfragmental diastase that allow to achieve spontaneous fracture stabilization in postoperative period even with substantial edge resorption of fragments. 114 patients (aged from 23 to 92 years) underwent 115 ope-rations using proposed device from February 2011 to July 2015. Results: positive results in the main clinical group, where proposed fixator was used, were obtained in 89 % cases. Conclusions: the device, that was worked out, is substentiated from anatomical-clinical positions and concepts of resorptive process within the remodeling of bone fragments. The technique is highly effective osteosynthesis even under adverse prognostic for bone-healing of medial femoral neck fractures (II–III type by Pauwels, III–IV typeby Garden) in patients of different age groups. Minimally invasive surgery technique enables organ-savings surgery for elderly patients, including those with co-morbidities.

In vivo corrosion behaviour of magnesium alloy in association with surrounding tissue response in rats

Biodegradable magnesium (Mg) alloys are the most promising candidates for osteosynthesis devices. However, their in vivo corrosion behaviour has not been fully elucidated. The aim of this study was to clarify the influence of the physiological environment surrounding Mg alloys on their corrosion behaviour. A Mg–1.0Al alloy with a fine-grained structure was formed into plates using titanium (Ti) as a control. These plates were implanted into the subperiosteum in the head, subcutaneous tissue of the back, and in the muscle of the femur of rats for 1, 2 and 4 weeks. The volumes of the remaining Mg alloy and of the insoluble salt deposition and gas cavities around the Mg alloy were determined by microtomography, and the volume losses were calculated. Then, the tissue response around the plates in each implantation site was examined histopathologically, and its relation to the respective volume loss was analyzed. These analyses determined that the Mg alloy was corroded fastest in the head, at an intermediate level in the back, and slowest in the femur. The insoluble salt deposition at the Mg alloy surface had no influence on the volume loss. Gas cavities formed around the Mg alloy at all implantation sites and decreased after 4 weeks. Histopathological examination revealed that the Mg alloy exhibited good biocompatibility, as was seen with Ti. In addition, vascularized fibrous capsules formed around the plates and became mature with time. Notably, the volume loss in the different anatomical locations correlated with capsule thickness. Together, our results suggest that, to facilitate the successful clinical application of Mg alloys, it will be necessary to further comprehend their interactions with specific in vivo environments.

MINIPLATE REMOVAL FOLLOWING MAXILLOFACIAL TRAUMA: ROUTINE OR SYMPTOMATIC?

Background: The literature shows that hardware removal rates after fixation of maxillofacial fractures with miniplates are significant, as there are some needs for hardware removal in a number of patients who have been treated with metallic osteosynthesis devices. purpose: The purpose of the present study was to find the rates of and reasons for miniplates removal in patients who have been treated for maxillofacial fractures. patients and methods: The files of 103 patients who have been treated with open reduction and internal fixation with titanium miniplates were retrospectively revised. The number of patients who underwent miniplate removal was recorded. For each patient who has undergone miniplate removal; the indication for miniplate removal, the number of removed plates and the interval between plate placement and removal were recorded. Results: 28 patients out of 103 patients have undergone miniplate removal with a total removal rate of 27.18 %. By excluding the pediatric population, the removal rate for the adult population alone was 9.6%. Twenty cases were removed due to ongoing growth in children and teenagers (71.43 %), five cases for objective reasons (17.85%) and three cases (10.71 %) due to subjective patient discomfort. A total of 51 plates were removed. Twelve plates (23.5 %) were removed from the mid-face and 39 (76.47 %) from the mandible. Conclusion: The low rate of miniplate removal in this study shows that the routine removal of asymptomatic miniplates in adult population is not indicated.