Mechanical properties of stainless steel orthopaedic implants in simulated biological conditions

Brojna su propitivanja potrebe rutinskog odstranjenja metalnog implantata nakon saniranja prijeloma kosti. Pretežita indikacija za odstranjenje jest slabljenje mehaničkih svojstava i pucanje implantata prije cijeljenja kosti. Cilj ovog istraživanja bio je ispitati mehanička svojstva osteosintetske pločice izrađene od standardnoga kirurškog čelika u simuliranim biološkim uvjetima. U istraživanju smo koristili implantate nehrđajućeg čelika 316L i pohranili ih kroz godinu dana u simuliranome biološkom mediju (engl. SBF – simulated body fluid). Analizirano je 48 pločica standardnoga kirurškog čelika podijeljeno u četiri skupine. Jedna je kontrolna. Ostale su bile uronjene u otopine različitih pH vrijednosti. Uronjene pločice testirane su nakon godinu dana, a kontrolna odmah na početku istraživanja. Tijekom godinu dana analizirala se promjena mikrostrukture uronjenih pločica skenirajući elektronskim mikroskopom (SEM) u pet navrata, a kontrolna grupa samo jednom. Na pločicama koje su bile u biološkim simuliranim uvjetima, bez obzira na pH medija, značajno je veći broj jamičastih korozija kod mjerenja nakon šest mjeseci i godinu dana. Nakon godinu dana pohrane u medijima različite pH mjerene su vrijednosti mehaničkog, statičkog i dinamičkog opterećenja pločica. Niti jedno načinjeno mehaničko testiranje nije pokazalo statistički značajnu razliku između kontrolne skupine pločica i onih koje su bile u biološki simuliranim uvjetima kroz godinu dana. Nepromijenjena mehanička svojstava istraživanih implantata, unatoč značajnim promjenama mikrostrukture nastale kao posljedica jamičaste korozije u biološki simuliranim uvjetima, otklanjaju vjerojatnost slabljenja pločice kao i indikaciju za njezino odstranjenje u tom vremenskom razdoblju.Questioning the routine metal implant removal after bone fracture healing has increased. One of the main indications for removal is metal weakening in biological bone healing conditions, in addition to reports about its breakage even prior to bone healing. The aim of this study is to investigate the mechanical properties of osteosynthesis plates made out of standard surgical stainless steel in simulated biological conditions. Implants made out of 316L stainless steel were kept for one year in simulated body fluid (SBF). We analysed 48 plates made out of standard surgical stainless steel that were divided in four groups. One was the control group and the remaining were immersed in solutions with various pH values according to pH changes during bone fracture healing. The immersed plates were tested mechanically through one year, and those in the control group at the beginning of the study. During one year microstructural changes of the immersed plates were examined five times using a scanning electron microscope (SEM), and only once in the control group. There were significant microstructural pitting corrosion changes after six months and after one year in all plates that were in simulated biological conditions, regardless of the group pH value. Static and dynamic mechanical plate loading tests were performed one year after storage in solutions with various pH values. Following the complete mechanical testing no statistically significant changes were found between groups kept in simulated biological conditions for one year and the control group. The study showed no changes in the mechanical properties of the investigated implants regardless of significant microstructural changes as a consequence of pitting corrosion in simulated biological conditions, which precludes the probability of implant weakening and indication for its removal one year after fracture fixation

The role of pitting corrosion in weakening osteosynthetic implants made of 316L stainless steel

Svrha rada: Ispitivanjem implantata od nehrđajućeg čelika 316L utvrditi djeluje li biološka tekuća (SBF-Simulated Body Fluid) sredina na biomehaničko slabljenje implantata kao posljedica jamičaste korozije. Očekivani znanstveni doprinos: Ovim istraživanjem nastoje se optimizirati svojstva implantata od čelika 316L koji se koristi u ortopedskoj i traumatološkoj kirurgiji. Materijali i metode: Četrdeset i osam (n = 48) uzoraka od nehrđajućeg čelika 316L, podijeljeni u četiri skupine od 12 uzoraka; prva skupina uronjena u SBF pH vrijednosti 7,0, druga uronjena u puferiranoj otopini mliječne kiseline pH vrijednosti 6,0, treća skupina uronjena u puferiranoj otopini mliječne kiseline pH vrijednosti 5,0 i četvrta skupina koja je kontrolna skupina te nije bila uronjena u otopine. Putem Skenirajućeg elektronskog mikroskopa (SEM) analizirao se broj po jedinici površine i dimenzije korozivnih promjena te su se pločice biomehanički testirale prije početka kod kontrolne skupine, i po završetku pokusa u ostalih skupina, kao i hrapavost. Rezultati: Za sve tri skupine koje su bile uronjene u SBF bilo je postupne progresije u promjenama po tipu jamičaste korozije i to najviše u skupini s najnižim pH (pH 5,0), odnosno s najvišom kiselošću i to od trećeg mjerenja nadalje (p = 0,003). Ako se gledaju vrijednosti unutar pojedinih vremena mjerenja, značajne razlike su između skupina pH 5,0 i pH 6,0 u četvrtom mjerenju kao i pH 5,0 i pH 7,0 u drugom mjerenju. U oba slučaja, vrijednosti površine jamica su bile najveće kod medija s najnižim pH vrijednostima. Ako promatramo dinamiku promjena unutar pojedinih skupina, značajne razlike su zabilježene samo u skupini s pH 6,0 (p = 0,001). Nije bilo značajnih razlika u vrijednostima maksimalnog progiba između ispitivanih skupina (p = 0,804). Razlike u maksimalnoj sili (N) tijekom statičkog mehaničkog opterećenja između pojedinih skupina koje su ovisno o kiselosti medija, pokazuje da je najniži medijan vrijednosti maksimalne sile bio kod kontrolne skupine: 1407 N (IQR: 1400 – 1471,5 N), a najviši kod pH 7,0: 1421,0 N (IQR: 1410,0 – 1491,5 N) iako između skupina nije bilo značajnih razlika. Zaključak: Implantati od nehrđajućeg čelika 316L u biološki simuliranom mediju razvijaju promjene po tipu jamičastih korozija, a kod onih već postojećih, znatno propagiraju u kiselijim uvjetima (najviše pH 5,0). Povezanost između jamičaste korozije i slabljenja implantata nije statistički značajna te se iz navedenog razloga nije nastavilo u stvaranju preporuka za optimizaciju debljine implantata ne bi li se izbjeglo oštećenje jamičastom korozijom.Aim: Assessing surgical 316L stainless steel to confirm the effect of biological media fluid (SBF-simulated body fluid) in weakening the implant due to pitting corrosion. Expected scientific contribution: This research is aimed to optimize the properties of implants made of 316L stainless steel used in orthopedic and trauma surgery. Materials and methods: Using forty-eight (n=48) 316L stainless steel implant samples divided into four groups of twelve samples each; the first immersed in SBF (saline 0.9% NaCl), second group immersed in a buffered lactic acid solution of pH 6.0, third group immersed in a buffered lactic acid solution of pH 5.0, and the fourth group is not immersed. The morphology and dimensions of corrosion defects analysed by a Scanning electron microscope (SEM), biomechanical tests performed at the beginning and end of the study. Results: There was a gradual increase in corrosion pits in all three groups that were immersed in SBF, with the most significant noted in the strongest acidic group (pH = 5.0), which was the case from the third measure onward (P=0.003). Upon inspecting the individual measurement times, there is a significant difference between groups of pH 5.0 and pH 6.0 in the fourth measurement, and also between the pH 5.0 and pH 7.0 groups. In both cases the surface area of the pits was the largest in the group immersed in the pH 5.0 solution. There was a significant statistical difference in the dynamics of change in only the group immersed in the pH 6.0 solution (P=0.001). There was no significant difference in maximal bending among the groups (P=0.804). The difference in the maximal force (N) during static mechanical testing of the groups was dependant on the acidity of the solution; the lowest median of maximal force was found in the control group: 1407 N (IQR: 1400 – 1471.5 N), the highest in the group of pH 7.0: 1421.0 N (IQR: 1410.0 – 1491.5 N); nonetheless, there was no significant difference between the groups. Conclusion: In concluding, 316L stainless steel implants in simulated body fluid with the lowest pH value develop corrosion pits, and additionally in existing ones, significantly progress in acidic conditions. There is no statistical significance in the relationship between pitting corrosion and the weakening of implants. The ideal thickness of the implant that would prevent pitting corrosion damage was not defined due to the irrelevance as mentioned above

The role of pitting corrosion in weakening osteosynthetic implants made of 316L stainless steel

Svrha rada: Ispitivanjem implantata od nehrđajućeg čelika 316L utvrditi djeluje li biološka tekuća (SBF-Simulated Body Fluid) sredina na biomehaničko slabljenje implantata kao posljedica jamičaste korozije. Očekivani znanstveni doprinos: Ovim istraživanjem nastoje se optimizirati svojstva implantata od čelika 316L koji se koristi u ortopedskoj i traumatološkoj kirurgiji. Materijali i metode: Četrdeset i osam (n = 48) uzoraka od nehrđajućeg čelika 316L, podijeljeni u četiri skupine od 12 uzoraka; prva skupina uronjena u SBF pH vrijednosti 7,0, druga uronjena u puferiranoj otopini mliječne kiseline pH vrijednosti 6,0, treća skupina uronjena u puferiranoj otopini mliječne kiseline pH vrijednosti 5,0 i četvrta skupina koja je kontrolna skupina te nije bila uronjena u otopine. Putem Skenirajućeg elektronskog mikroskopa (SEM) analizirao se broj po jedinici površine i dimenzije korozivnih promjena te su se pločice biomehanički testirale prije početka kod kontrolne skupine, i po završetku pokusa u ostalih skupina, kao i hrapavost. Rezultati: Za sve tri skupine koje su bile uronjene u SBF bilo je postupne progresije u promjenama po tipu jamičaste korozije i to najviše u skupini s najnižim pH (pH 5,0), odnosno s najvišom kiselošću i to od trećeg mjerenja nadalje (p = 0,003). Ako se gledaju vrijednosti unutar pojedinih vremena mjerenja, značajne razlike su između skupina pH 5,0 i pH 6,0 u četvrtom mjerenju kao i pH 5,0 i pH 7,0 u drugom mjerenju. U oba slučaja, vrijednosti površine jamica su bile najveće kod medija s najnižim pH vrijednostima. Ako promatramo dinamiku promjena unutar pojedinih skupina, značajne razlike su zabilježene samo u skupini s pH 6,0 (p = 0,001). Nije bilo značajnih razlika u vrijednostima maksimalnog progiba između ispitivanih skupina (p = 0,804). Razlike u maksimalnoj sili (N) tijekom statičkog mehaničkog opterećenja između pojedinih skupina koje su ovisno o kiselosti medija, pokazuje da je najniži medijan vrijednosti maksimalne sile bio kod kontrolne skupine: 1407 N (IQR: 1400 – 1471,5 N), a najviši kod pH 7,0: 1421,0 N (IQR: 1410,0 – 1491,5 N) iako između skupina nije bilo značajnih razlika. Zaključak: Implantati od nehrđajućeg čelika 316L u biološki simuliranom mediju razvijaju promjene po tipu jamičastih korozija, a kod onih već postojećih, znatno propagiraju u kiselijim uvjetima (najviše pH 5,0). Povezanost između jamičaste korozije i slabljenja implantata nije statistički značajna te se iz navedenog razloga nije nastavilo u stvaranju preporuka za optimizaciju debljine implantata ne bi li se izbjeglo oštećenje jamičastom korozijom.Aim: Assessing surgical 316L stainless steel to confirm the effect of biological media fluid (SBF-simulated body fluid) in weakening the implant due to pitting corrosion. Expected scientific contribution: This research is aimed to optimize the properties of implants made of 316L stainless steel used in orthopedic and trauma surgery. Materials and methods: Using forty-eight (n=48) 316L stainless steel implant samples divided into four groups of twelve samples each; the first immersed in SBF (saline 0.9% NaCl), second group immersed in a buffered lactic acid solution of pH 6.0, third group immersed in a buffered lactic acid solution of pH 5.0, and the fourth group is not immersed. The morphology and dimensions of corrosion defects analysed by a Scanning electron microscope (SEM), biomechanical tests performed at the beginning and end of the study. Results: There was a gradual increase in corrosion pits in all three groups that were immersed in SBF, with the most significant noted in the strongest acidic group (pH = 5.0), which was the case from the third measure onward (P=0.003). Upon inspecting the individual measurement times, there is a significant difference between groups of pH 5.0 and pH 6.0 in the fourth measurement, and also between the pH 5.0 and pH 7.0 groups. In both cases the surface area of the pits was the largest in the group immersed in the pH 5.0 solution. There was a significant statistical difference in the dynamics of change in only the group immersed in the pH 6.0 solution (P=0.001). There was no significant difference in maximal bending among the groups (P=0.804). The difference in the maximal force (N) during static mechanical testing of the groups was dependant on the acidity of the solution; the lowest median of maximal force was found in the control group: 1407 N (IQR: 1400 – 1471.5 N), the highest in the group of pH 7.0: 1421.0 N (IQR: 1410.0 – 1491.5 N); nonetheless, there was no significant difference between the groups. Conclusion: In concluding, 316L stainless steel implants in simulated body fluid with the lowest pH value develop corrosion pits, and additionally in existing ones, significantly progress in acidic conditions. There is no statistical significance in the relationship between pitting corrosion and the weakening of implants. The ideal thickness of the implant that would prevent pitting corrosion damage was not defined due to the irrelevance as mentioned above

The role of pitting corrosion in weakening osteosynthetic implants made of 316L stainless steel

Svrha rada: Ispitivanjem implantata od nehrđajućeg čelika 316L utvrditi djeluje li biološka tekuća (SBF-Simulated Body Fluid) sredina na biomehaničko slabljenje implantata kao posljedica jamičaste korozije. Očekivani znanstveni doprinos: Ovim istraživanjem nastoje se optimizirati svojstva implantata od čelika 316L koji se koristi u ortopedskoj i traumatološkoj kirurgiji. Materijali i metode: Četrdeset i osam (n = 48) uzoraka od nehrđajućeg čelika 316L, podijeljeni u četiri skupine od 12 uzoraka; prva skupina uronjena u SBF pH vrijednosti 7,0, druga uronjena u puferiranoj otopini mliječne kiseline pH vrijednosti 6,0, treća skupina uronjena u puferiranoj otopini mliječne kiseline pH vrijednosti 5,0 i četvrta skupina koja je kontrolna skupina te nije bila uronjena u otopine. Putem Skenirajućeg elektronskog mikroskopa (SEM) analizirao se broj po jedinici površine i dimenzije korozivnih promjena te su se pločice biomehanički testirale prije početka kod kontrolne skupine, i po završetku pokusa u ostalih skupina, kao i hrapavost. Rezultati: Za sve tri skupine koje su bile uronjene u SBF bilo je postupne progresije u promjenama po tipu jamičaste korozije i to najviše u skupini s najnižim pH (pH 5,0), odnosno s najvišom kiselošću i to od trećeg mjerenja nadalje (p = 0,003). Ako se gledaju vrijednosti unutar pojedinih vremena mjerenja, značajne razlike su između skupina pH 5,0 i pH 6,0 u četvrtom mjerenju kao i pH 5,0 i pH 7,0 u drugom mjerenju. U oba slučaja, vrijednosti površine jamica su bile najveće kod medija s najnižim pH vrijednostima. Ako promatramo dinamiku promjena unutar pojedinih skupina, značajne razlike su zabilježene samo u skupini s pH 6,0 (p = 0,001). Nije bilo značajnih razlika u vrijednostima maksimalnog progiba između ispitivanih skupina (p = 0,804). Razlike u maksimalnoj sili (N) tijekom statičkog mehaničkog opterećenja između pojedinih skupina koje su ovisno o kiselosti medija, pokazuje da je najniži medijan vrijednosti maksimalne sile bio kod kontrolne skupine: 1407 N (IQR: 1400 – 1471,5 N), a najviši kod pH 7,0: 1421,0 N (IQR: 1410,0 – 1491,5 N) iako između skupina nije bilo značajnih razlika. Zaključak: Implantati od nehrđajućeg čelika 316L u biološki simuliranom mediju razvijaju promjene po tipu jamičastih korozija, a kod onih već postojećih, znatno propagiraju u kiselijim uvjetima (najviše pH 5,0). Povezanost između jamičaste korozije i slabljenja implantata nije statistički značajna te se iz navedenog razloga nije nastavilo u stvaranju preporuka za optimizaciju debljine implantata ne bi li se izbjeglo oštećenje jamičastom korozijom.Aim: Assessing surgical 316L stainless steel to confirm the effect of biological media fluid (SBF-simulated body fluid) in weakening the implant due to pitting corrosion. Expected scientific contribution: This research is aimed to optimize the properties of implants made of 316L stainless steel used in orthopedic and trauma surgery. Materials and methods: Using forty-eight (n=48) 316L stainless steel implant samples divided into four groups of twelve samples each; the first immersed in SBF (saline 0.9% NaCl), second group immersed in a buffered lactic acid solution of pH 6.0, third group immersed in a buffered lactic acid solution of pH 5.0, and the fourth group is not immersed. The morphology and dimensions of corrosion defects analysed by a Scanning electron microscope (SEM), biomechanical tests performed at the beginning and end of the study. Results: There was a gradual increase in corrosion pits in all three groups that were immersed in SBF, with the most significant noted in the strongest acidic group (pH = 5.0), which was the case from the third measure onward (P=0.003). Upon inspecting the individual measurement times, there is a significant difference between groups of pH 5.0 and pH 6.0 in the fourth measurement, and also between the pH 5.0 and pH 7.0 groups. In both cases the surface area of the pits was the largest in the group immersed in the pH 5.0 solution. There was a significant statistical difference in the dynamics of change in only the group immersed in the pH 6.0 solution (P=0.001). There was no significant difference in maximal bending among the groups (P=0.804). The difference in the maximal force (N) during static mechanical testing of the groups was dependant on the acidity of the solution; the lowest median of maximal force was found in the control group: 1407 N (IQR: 1400 – 1471.5 N), the highest in the group of pH 7.0: 1421.0 N (IQR: 1410.0 – 1491.5 N); nonetheless, there was no significant difference between the groups. Conclusion: In concluding, 316L stainless steel implants in simulated body fluid with the lowest pH value develop corrosion pits, and additionally in existing ones, significantly progress in acidic conditions. There is no statistical significance in the relationship between pitting corrosion and the weakening of implants. The ideal thickness of the implant that would prevent pitting corrosion damage was not defined due to the irrelevance as mentioned above

Mathematical approximation of fibular malleolus curvature

While there are several manuscripts describing the articular surfaces of the ankle joint and the fibula itself, there is no study describing the outer surface and the degree of curvature of the fibular malleolus. This paper aims to approximate the sagital curvature of the outer surface of the lateral malleolus mathematically. Such data would facilitate the design of the anatomic plate that can be used for the ostheosynthesis of the fibular malleolus fracture. 30 males who were examined in the emergency department due to ankle sprains, where they underwent a standard anteroposterior x-ray of the ankle in the neutral position were recruited. The radiographs which revealed no bony injury were digitized and statistically processed. A mathematical function for each separate fibula was obtained through the processing of the digitized x-rays. When all the functions were applied to one graph, common traits of all fibulas were noted. The mean value of all functions was obtained and it corresponds to the polynomial function of degree 6. Mathematical approximation of the curvature is a simple and reliable method that can be applied to other ellipsoid human bone structures besides the ankle, thus being a valuable method in anthropometric, radiological and virtual geometric calculations

Stable Gastric Pentadecapeptide BPC 157 May Recover Brain–Gut Axis and Gut–Brain Axis Function

Conceptually, a wide beneficial effect, both peripherally and centrally, might have been essential for the harmony of brain–gut and gut–brain axes’ function. Seen from the original viewpoint of the gut peptides’ significance and brain relation, the favorable stable gastric pentadecapeptide BPC 157 evidence in the brain–gut and gut–brain axes’ function might have been presented as a particular interconnected network. These were the behavioral findings (interaction with main systems, anxiolytic, anticonvulsive, antidepressant effect, counteracted catalepsy, and positive and negative schizophrenia symptoms models). Muscle healing and function recovery appeared as the therapeutic effects of BPC 157 on the various muscle disabilities of a multitude of causes, both peripheral and central. Heart failure was counteracted (including arrhythmias and thrombosis), and smooth muscle function recovered. These existed as a multimodal muscle axis impact on muscle function and healing as a function of the brain–gut axis and gut–brain axis as whole. Finally, encephalopathies, acting simultaneously in both the periphery and central nervous system, BPC 157 counteracted stomach and liver lesions and various encephalopathies in NSAIDs and insulin rats. BPC 157 therapy by rapidly activated collateral pathways counteracted the vascular and multiorgan failure concomitant to major vessel occlusion and, similar to noxious procedures, reversed initiated multicausal noxious circuit of the occlusion/occlusion-like syndrome. Severe intracranial (superior sagittal sinus) hypertension, portal and caval hypertensions, and aortal hypotension were attenuated/eliminated. Counteracted were the severe lesions in the brain, lungs, liver, kidney, and gastrointestinal tract. In particular, progressing thrombosis, both peripherally and centrally, and heart arrhythmias and infarction that would consistently occur were fully counteracted and/or almost annihilated. To conclude, we suggest further BPC 157 therapy applications