A Method for Prediction of Femoral Component of Hip Prosthesis Durability due to Aseptic Loosening by Using Coffin/Manson Fatigue Model

The purpose of this work is to develop a new model estimate of the fatigue life of a hip prosthesis due to aseptic loosening as a multifactorial phenomenon. The formula developed here is a three-parameter model based on Basquin’s law for fatigue, eccentric compression formula for the compressive stress and torsion in the prosthesis due to the horizontal components of the contact force. With our model, we can accurately predict the durability of a hip prosthesis due to the following four parameters: body weight, femoral offset, duration, and intensity of daily physical activities of a patient. The agreement of the prediction with the real life of the prosthesis, observed on 15 patients, is found to be adequate. Based on the formula derived for a particular implant, there was a high degree of concurrence between the model-predicted and actual values of aseptic loosening (durability) proved by the Mann–Whitney U test. By virtue of the validated model, it is possible to predict, quantitatively, the influence of various factors on the hip life. For example, we can conclude that a 10% decrease of a patient’s body mass, with all other conditions being the same, causes 5% increase of the hip fatigue life

An Extremely Rare Case of Cementless Third Generation Corail Stem Neck Fracture With Fractographic Analysis

The cementless Corail stem is one of the most frequently implanted stems and has undergone several design changes. Currently in use is the third generation, named Corail AMT. Until now, only one third-generation Corail stem neck fracture has been described in 2020. In our paper, we present an almost identical complication with an additional analysis of the fracture using a scanning electron microscope. The revision surgery consisted of changing the broken implant with a Corail revision stem, along with replacing the polyethylene liner and the femoral head with new one, after which the patient achieved a full recovery. According to the available literature, this is the second case of this extremely rare complication

Association of gene variants in TLR4 and IL-6 genes with Perthes disease

Uvod Pertesova bolest je idiopatska avaskularna osteonekroza proksimalne epifize femura koja se javlja kod dece. Etiologija ove bolesti je nepoznata. Tokom razvoja Pertesove bolesti zastupljen je proces zapaljenja, za koji je pokazano da utiče na remodelovanje koštanog tkiva. Cilj rada S obzirom na to da genetički faktori koji utiču na proces zapaljenja dosad nisu ispitivani kod Pertesove bolesti, cilj ovog istraživanja je bio da se utvrdi povezanost učestalosti varijanti u genima koji učestvuju u inflamatornom odgovoru, TLR4 (engl. toll-like receptor 4) i IL-6 (interleukin 6), i ove bolesti. Metode rada Ispitano je 37 dece s Pertesovom bolešću i 50 zdravih osoba. Metodom PCR-RFLP određeni su polimorfizmi medijatora zapaljenja TLR4 (Asp299Gly, Thr399Ile) i IL-6 (G-174C, G-597A). Rezultati Pokazano je da su polimorfizmi IL-6 G-174C i G-597A u našem ispitivanju bili u potpunoj gametskoj neravnoteži vezanosti. U kontrolnoj grupi je bilo statistički značajno više nosilaca heterozigotnog genotipa IL-6 G-174C/G-597A u poređenju sa grupom ispitanika s Pertesovom bolešću (p=0,047; OR=2,49; 95% CI=1,00-6,21). Takođe, grupa bolesnika nije bila u Hardi- Vajnbergovoj ravnoteži za polimorfizme IL-6 G-174C/G-597A. Nije primećena statistički značajna razlika u raspodeli genotipova za polimorfizme analizirane u TLR4 genu. Raspodela genotipova među grupama bolesnika formiranih na osnovu uzrasta kada se bolest pojavila nije pokazala statistički značajnu povezanost s analiziranim polimorfizmima. Zaključak Naše istraživanje je pokazalo da su nosioci heterozigotnog genotipa za IL-6 G-174C/G-597A polimorfizme bili značajno češći u kontrolnoj grupi nego u grupi dece obolele od Pertesove bolesti. Na osnovu toga zaključili smo da je kod dece koja su nosioci heterozigotnog genotipa za ove polimorfizme manja verovatnoća za razvoj Pertesove bolesti nego kod nosilaca oba homozigotna genotipa.Introduction Perthes disease is idiopathic avascular osteonecrosis of the hip in children, with unknown etiology. Inflammation is present during development of Perthes disease and it is known that this process influences bone remodeling. Objective Since genetic studies related to inflammation have not been performed in Perthes disease so far, the aim of this study was to analyze the association of frequencies of genetic variants of immune response genes, toll-like receptor 4 (TLR4) and interleukin-6 (IL-6), with this disease. Methods The study cohort consisted of 37 patients with Perthes disease and 50 healthy controls. Polymorphisms of well described inflammatory mediators: TLR4 (Asp299Gly, Thr399Ile) and IL-6 (G-174C, G- 597A) were determined by polymerase chain reaction restriction fragment length polymorphism method. Results IL-6 G-174C and G-597A polymorphisms were in complete linkage disequilibrium. A statistically significant increase of heterozygote subjects for IL-6 G-174C/G-597A was found in controls in comparison to Perthes patient group (p=0.047, OR=2.49, 95% CI=1.00-6.21). Also, the patient group for IL-6 G-174C/G- 597A polymorphisms was not in Hardy-Weinberg equilibrium. No statistically significant differences were found between patient and control groups for TLR4 analyzed polymorphisms. A stratified analysis by the age at disease onset also did not reveal any significant difference for all analyzed polymorphisms. Conclusion Our study revealed that heterozygote subjects for the IL-6 G-174C/G-597A polymorphisms were significantly overrepresented in the control group than in the Perthes patient group. Consequently, we concluded that children who are heterozygous for these polymorphisms have a lower chance of developing Perthes disease than carriers of both homozygote genotypes