A probabilistic approach for assessing the mechanical performance of intertrochanteric fracture stabilized with proximal femoral nail antirotation.

Maintaining post-operative mechanical stability is crucial for successfully healing intertrochanteric fractures treated with the Proximal Femoral Nail Antirotation (PFNA) system. This stability is primarily dependent on the bone mineral density (BMD) and strain on the fracture. Current PFNA failure analyses often overlook the uncertainties related to BMD and body weight (BW). Therefore, this study aimed to develop a probabilistic model using finite element modeling and engineering reliability analysis to assess the post-operative performance of PFNA under various physiological loading conditions. The model predictions were validated through a series of experimental test. The results revealed a negative nonlinear relationship between the BMD and compressive strain. Conversely, the BW was positively and linearly correlated with the compressive strain. Importantly, the compressive strain was more sensitive to BW than to BMD when the BMD exceeded 0.6 g/cm3. Potential trabecular bone compression failure is also indicated if BMD is equal to or below 0.15 g/cm3 and BW increases to approximately 2.5 times the normal or higher. This study emphasizes that variations in the BMD significantly affect the probability of failure of a PFNA system. Thus, careful planning of post-operative physical therapy is essential. For patients aged > 50 years restrictions on high-intensity activities are advised, while limiting strenuous movements is recommended for those aged > 65 years.

One-year performance of biorestorative polymeric coronary bypass grafts in an ovine model: correlation between early biomechanics and late serial Quantitative Flow Ratio.

OBJECTIVES: This study aimed to investigate the impact of mechanical factors at baseline on the patency of a restorative conduit for coronary bypass grafts in an ovine model at serial follow-up up to 1 year. METHODS: The analyses of 4 mechanical factors [i.e. bending angle, superficial wall strain and minimum and maximum endothelial shear stress (ESS)] were performed in 3D graft models reconstructed on baseline (1-month) angiograms frame by frame by a core laboratory blinded for the late follow-up. The late patency was documented by Quantitative Flow Ratio (QFR®) that reflects the physiological status of the graft. The correlation between 4 mechanical factors and segmental QFR (△QFR) were analysed on 10 equal-length segments of each graft. RESULTS: A total of 69 graft geometries of 7 animals were performed in the study. The highest △QFR at 12 months was colocalized in segments of the grafts with the largest bending angles at baseline. Higher △QFR at 3 months were both at the anastomotic ends and were colocalized with the highest superficial wall strain at baseline. High baseline ESS was topographically associated with higher △QFR at the latest follow-up. Correlations of minimum and maximum ESS with △QFR at 3 months were the strongest among these parameters (ρ = 0.30, 95% CI [-0.05 to 0.56] and ρ = 0.27, 95% CI [-0.05 to 0.54], respectively). CONCLUSIONS: Despite the limited number of grafts, this study suggests an association between early abnormal mechanical factors and late flow metrics of the grafts. The understanding of the mechanical characteristics could help to improve this novel conduit.

Comparisons on enhancing the immunity of fresh and dry Cordyceps militaris in vivo and in vitro.

ETHNOPHARMACOLOGICAL RELEVANCE: The immunomodulatory capacities of fresh Cordyceps militaris (FCM) and dry Cordyceps militaris (DCM) were compared. MATERIALS AND METHODS: In vivo immunomodulatory assay, different doses of FCM and DCM were orally administrated over a period of 15 days in a cyclophosphamide (CY) induced immunosuppression mice; in vitro testing, the spleen cells were extracted from healthy mice and treaded with CY, then cultured with different dose of FCM or DCM; the contents of Cordyceps militaris polysaccharide (CMP), cordycepin, adenosine, total polyphenol (TP) and total flavonoids (TF) in FCM and DCM were measured. RESULTS: Our studys indicated that, FCM was significantly stronger than DCM on increasing the spleen and thymus indexes, spleen lymphocyte activity, macrophage function, and promoting the levels of IL-2, IFN-γ in vivo and in vitro. The contents of immunomodulatory CMP and TF in FCM were markedly higher than in DCM. CONCLUSION: All these results suggested that FCM was superior to DCM on enhancing immunity.