Fixation of Small Osteochondral Fragments in a Comminuted Distal Humerus Fracture with Magnesium Bioabsorbable Screws: A Case Report

Management of Pediatric Elbow Fractures and Dislocations

Pediatric elbow fractures and dislocations have always been a challenge from a diagnostic and therapeutic point of view, primarily due to the complex nature of the pediatric elbow, especially its developmental anatomy. They must be diagnosed and treated on time to prevent numerous complications with long-term consequences. With the development of radiology and pediatric surgery and orthopedics, as well as the development of modern osteosynthesis materials, concerning current scientific and professional knowledge, the outcomes are getting better, with fewer acute and chronic complications. This comprehensive review aims to provide clinicians current knowledge about pediatric elbow fractures and dislocations so that in daily practice they have as few doubts as possible with the best possible treatment outcomes.

Peri-articular elbow fracture fixations with magnesium implants and a review of current literature: A case series

BACKGROUND

In recent years, the use of Magnesium alloy implants have gained renewed popularity, especially after the first commercially available Conformité Européenne approved Magnesium implant became available (MAGNEZIX® CS, Syntellix) in 2013.

AIM

To document our clinical and radiographical outcomes using magnesium implants in treating peri-articular elbow fractures.

METHODS

Our paper was based on a retrospective case series design. Intra-operatively, a standardized surgical technique was utilized for insertion of the magnesium implants. Post - operatively, clinic visits were standardized and physical exam findings, functional scores, and radiographs were obtained at each visit. All complications were recorded.

RESULTS

Five patients with 6 fractures were recruited (2 coronoid, 3 radial head and 1 capitellum). The mean patient age and length of follow up was 54.6 years and 11 months respectively. All fractures healed, and none exhibited loss of reduction or complications requiring revision surgery. No patient developed synovitis of the elbow joint or suffered electrolytic reactions when titanium implants were used concurrently.

CONCLUSION

Although there is still a paucity of literature available on the subject and further studies are required, magnesium implants appear to be a feasible tool for fixation of peri-articular elbow fractures with promising results in our series.

Magnesium-Based Alloys Used in Orthopedic Surgery

Magnesium (Mg)-based alloys have become an important category of materials that is attracting more and more attention due to their high potential use as orthopedic temporary implants. These alloys are a viable alternative to nondegradable metals implants in orthopedics. In this paper, a detailed overview covering alloy development and manufacturing techniques is described. Further, important attributes for Mg-based alloys involved in orthopedic implants fabrication, physiological and toxicological effects of each alloying element, mechanical properties, osteogenesis, and angiogenesis of Mg are presented. A section detailing the main biocompatible Mg-based alloys, with examples of mechanical properties, degradation behavior, and cytotoxicity tests related to in vitro experiments, is also provided. Special attention is given to animal testing, and the clinical translation is also reviewed, focusing on the main clinical cases that were conducted under human use approval.

Osteosynthesis devices in absorbable Magnesium alloy in comparison to standard ones: a Systematic Review on effectiveness and safety

BACKGROUND AND AIM OF THE WORK

Magnesium (Mg) is a metal physiologically present in bone tissue and essential for bone health. Mg-based-alloys exhibit mechanical properties, namely density and strength, similar to human cortical bone. These features have been exploited for the development of osteosynthesis devices in biodegradable Mg-based-alloys. Accordingly, the aim of this study was to rank the effectiveness and safety of Mg-based alloys applied in bone surgery in comparison to other suitable metals, focusing in particular on Mg superior biocompatibility and biodegradability.

METHODS

a systematic-review of the literature was conducted including only primary research studies dealing with patients suffering from fractured or osteotomized bones fixed using Mg-based osteosynthesis-devices.

RESULTS

literature revision suggested Mg-alloys holding comparable properties and side effects in comparison with titanium (Ti) screws, thus showing similar efficacy and safety. In particular, the gas formation in the carpal bones was identified as the main side effect of the Mg-alloys, during the corrosion/degradation phase of Mg.

CONCLUSIONS

according to the considered literature, the main advantages exploiting Mg-alloys for bone implants are related to their biocompatibility, bio-absorbability/-degradability, the lack of surgical removal, osteoconductivity and antibacterial activity. On the opposite, the main limitation of Mg-alloys is due to the poor mechanical resistance of small devices for internal fixation of bone fragments that lack of sufficient strength to withstand high forces. Therefore, an important future prospect could rely in the development of innovative hybrid systems aimed at fixing high load-bearing fractures, as well as in regenerative-medicine by developing new Mg-based engineered scaffolds.

Bio-corrosion impacts on mechanical integrity of ZM21 Mg for orthopaedic implant application processed by equal channel angular pressing

The mechanical integrity of rolled ZM21 Mg was improved by equal channel angular pressing (ECAP) to function as a potential biodegradable bone screw implant. Electron backscattered diffraction (EBSD) revealed deformed grains of 45 µm observed in rolled ZM21 Mg. They were transformed to equiaxed fine grains of 5.4 µm after 4^th pass ECAP. The yield strength of rolled and ECAPed ZM21 Mg alloys were comparable. In contrast, 4^th pass ZM21 Mg exhibited relatively higher elongation when compared to rolled sample. The mechanical properties of rolled and ECAPed ZM21 Mg were dependant on both grain refinement and crystallographic texture. The rolled and 4^th pass ECAPed tensile samples exhibited nonlinear deterioration of mechanical properties when tested after 7, 14, 21 and 28 days immersion in Hank's solution. The evaluation signifies that regardless their processing condition, ZM21 Mg alloys are suitable for surgical areas that requires high mechanical strength. In addition, the 4^th pass ECAP samples were viable to MG-63 cells proving themselves to be promising candidates for future in vivo studies.

Use of resorbable magnesium screws in children: systematic review of the literature and short-term follow-up from our series

PURPOSE

Biodegradable implants are of major interest in orthopaedics, especially in the skeletally immature population. Magnesium (Mg) implants are promising for selected surgical procedure in adults, but evidence is lacking. Thus, the aim of this study is to analyze the safety and efficacy of resorbable Mg screw in different orthopaedic procedures in skeletally immature patients. In addition, we present a systematic review of the current literature on the clinical use of Mg implants.

METHODS

From 2018 until the writing of this manuscript, consecutive orthopaedic surgical procedures involving the use of Mg screws performed at our centre in patients < 15 years of age were retrospectively reviewed. In addition, a systematic review of the literature was performed in the main databases. We included clinical studies conducted on humans, using Mg-alloy implants for orthopaedic procedures.

RESULTS

A total of 14 patients were included in this retrospective analysis. Mean age at surgery was 10.8 years (sd 2.4), mean follow-up was 13.8 months (sd 7.5). Healing was achieved in all the procedures, with no implant-related adverse reaction. No patients required any second surgical procedure. The systematic review evidenced 20 clinical studies, 19 of which conducted on an adult and one including paediatric patients.

CONCLUSION

Evidence on resorbable Mg implants is low but promising in adults and nearly absent in children. Our series included apophyseal avulsion, epiphyseal fractures, osteochondritis dissecans, displaced osteochondral fragment and tendon-to-bone fixation. Mg screws guaranteed stable fixation, without implant failure, with good clinical and radiological results and no adverse events.

LEVEL OF EVIDENCE

IV - Single cohort retrospective analysis with systematic review.

Research status of biodegradable metals designed for oral and maxillofacial applications: A review

The oral and maxillofacial regions have complex anatomical structures and different tissue types, which have vital health and aesthetic functions. Biodegradable metals (BMs) is a promising bioactive materials to treat oral and maxillofacial diseases. This review summarizes the research status and future research directions of BMs for oral and maxillofacial applications. Mg-based BMs and Zn-based BMs for bone fracture fixation systems, and guided bone regeneration (GBR) membranes, are discussed in detail. Zn-based BMs with a moderate degradation rate and superior mechanical properties for GBR membranes show great potential for clinical translation. Fe-based BMs have a relatively low degradation rate and insoluble degradation products, which greatly limit their application and clinical translation. Furthermore, we proposed potential future research directions for BMs in the oral and maxillofacial regions, including 3D printed BM bone scaffolds, surface modification for BMs GBR membranes, and BMs containing hydrogels for cartilage regeneration, soft tissue regeneration, and nerve regeneration. Taken together, the progress made in the development of BMs in oral and maxillofacial regions has laid a foundation for further clinical translation.

Bioresorbable Magnesium-Based Alloys as Novel Biomaterials in Oral Bone Regeneration: General Review and Clinical Perspectives

Bone preservation and primary regeneration is a daily challenge in the field of dental medicine. In recent years, bioresorbable metals based on magnesium (Mg) have been widely investigated due to their bone-like modulus of elasticity, their high biocompatibility, antimicrobial, and osteoconductive properties. Synthetic Mg-based biomaterials are promising candidates for bone regeneration in comparison with other currently available pure synthetic materials. Different alloys based on Mg were developed to fit clinical requirements. In parallel, advances in additive manufacturing offer the possibility to fabricate experimentally bioresorbable metallic porous scaffolds. This review describes the promising clinical results of resorbable Mg-based biomaterials for bone repair in osteosynthetic application and discusses the perspectives of use in oral bone regeneration.

A lean bioabsorbable magnesium-zinc-calcium alloy ZX00 used for operative treatment of medial malleolus fractures: early clinical results of a prospective non-randomized first in man study

Aims

This study is a prospective, non-randomized trial for the treatment of fractures of the medial malleolus using lean, bioabsorbable, rare-earth element (REE)-free, magnesium (Mg)-based biodegradable screws in the adult skeleton.

Methods

A total of 20 patients with isolated, bimalleolar, or trimalleolar ankle fractures were recruited between July 2018 and October 2019. Fracture reduction was achieved through bioabsorbable Mg-based screws composed of pure Mg alloyed with zinc (Zn) and calcium (Ca) ( Mg-Zn0.45-Ca0.45, in wt.%; ZX00). Visual analogue scale (VAS) and the presence of complications (adverse events) during follow-up (12 weeks) were used to evaluate the clinical outcomes. The functional outcomes were analyzed through the range of motion (ROM) of the ankle joint and the American Orthopaedic Foot and Ankle Society (AOFAS) score. Fracture reduction and gas formation were assessed using several plane radiographs.

Results

The follow-up was performed after at least 12 weeks. The mean difference in ROM of the talocrural joint between the treated and the non-treated sites decreased from 39° (SD 12°) after two weeks to 8° (SD 11°) after 12 weeks (p ≤ 0.05). After 12 weeks, the mean AOFAS score was 92.5 points (SD 4.1). Blood analysis revealed that Mg and Ca were within a physiologically normal range. All ankle fractures were reduced and stabilized sufficiently by two Mg screws. A complete consolidation of all fractures was achieved. No loosening or breakage of screws was observed.

Conclusion

This first prospective clinical investigation of fracture reduction and fixation using lean, bioabsorbable, REE-free ZX00 screws showed excellent clinical and functional outcomes.

Cite this article: Bone Joint Res 2020;9(8):477–483.