The Biomechanical Role of the Fibula in Lower Limbs: A Fracture Mechanics Analysis

BackgroundFibular grafting is widely used in the treatment of various bone nonunions and defects because of its good therapeutic effects. Furthermore, partial fibular resection has been used as a treatment for fibular tumors, injuries, and other conditions. The fibula plays important roles in the biomechanics of the lower limbs. Some experts have used cadaver specimens to study these aspects. In this study, the biomechanical effects of the fibula in lower limbs were researched through mechanics analysis.MethodsWe randomly collected knee joint computed tomography (CT) scans from eight adults, including three left knees and five right knees. The DICOM formatted CT scan images were imported into Mimics software. The tibia and fibula were extracted with the CT-bone function in Mimics software, and 3D models of the tibia and fibula were obtained. Each model was imported into 3-MATIC and LS-DYNA software to smooth the surface, perform meshing, define material properties, and set the failure parameters, interface properties, vertical loads and boundary conditions. The tibial fractures in both models were calculated to evaluate the biomechanical role of the fibula in the lower leg.ResultsThe validity of the model was verified, and the fibular load condition was similar to those previously reported. In the model with fibular support, the fracture load of the tibia was 78.27±3.36 KN, the initial fracture time was 0.69±0.01 s, and the complete fracture time was 0.75±0.01 s. The fibula carried approximately 7% of the load on the lower leg. In the fibular defect model, the fracture load of the tibia was 72.71±3.25 KN, the initial fracture time was 0.54±0.02 s, and the complete fracture time was 0.62±0.01 s.ConclusionsThe fibula play an essential biomechanical role in lower limb load-bearing and therefore is worthy of clinical attention. We believe that LS-DYNA can be used as an effective tool for the study of fracture mechanics.

Biomechanical Role of Fibula in Lower Limbs: a Fracture Mechanics Analysis

Background Fibular grafting is widely used in the treatment of various bone nonunion and bone defect because of its good therapeutic effect. Besides, partial fibular resection has also been used as a treatment for fibular tumors, injuries, etc. However, fibula plays an important role in the biomechanics of the lower limbs. Some experts have used cadaver specimens to study these aspect. In this study, the biomechanical effects of fibula in lower limbs were researched based on mechanics analysis.Methods The CT image data of a middle-aged male normal knee joint were selected. The tibia and fibula were extracted by CT-bone function in Mimics software, and the 3D model of tibia and fibula was obtained. The model was imported into 3-matic and LS-DYNA software to smooth the surface, mesh, define material properties, set failure parameters and interface properties, and set vertical loads and boundary conditions. The tibial fractures in both models were calculated to evaluate the biomechanical role of the fibula in the lower leg.Results The validity of the model was verified, and the fibula load condition was similar to the previous references. In the model with fibula support, the fracture load of the tibia was 78.5KN, the initial fracture time was 0.67164S, and the complete fracture time was 0.73225S. The fibula distributes about 7% of the load on the lower leg. In the fibula defect model, the fracture load of tibia was 73.5KN, the initial fracture time was 0.54034S, and the complete fracture time was 0.61105S.Conclusions Fibula plays an irreplaceable biomechanical role in the process of lower limb load-bearing, which is worthy of clinical attention. Meanwhile, LS-DYNA can be used as an effective tool for bone fracture and numerical analysis.

Contralateral non-simultaneous proximal femoral fractures in patients over 65 years old

Purpose Epidemiological and clinical parameters according to the Parker-Palmer Index (PPI) have not been specifically studied as predictors of re-fracture time in patients over 65 years old with contralateral hip fracture. The main purpose of this study was to assess whether these parameters could represent a prognostic factor in this population. Methods This retrospective study included all consecutive patients older than 65 years that suffered from a proximal femoral fracture, 31 according to Association for Osteosynthesis/Orthopaedic Trauma Association classification, treated at our unit between Feb 1st 2019 and Feb 1st 2020. Results This study enrolled 387 patients. Thirty-seven of them had already incurred a contralateral hip fracture: seven males and 30 females. The median time between the first and second hip fractures was 3.5 years. This study revealed that increasing age (p = 0.003), male sex (p = 0.029) and a PPI value ≥ 5 between the first and second hip fracture (p = 0.015) are risk factors associated with a contralateral hip fracture in the first three years after the first episode. There were no statistically significant differences regarding anti-osteoporotic therapy and the anatomic site of the first hip fracture episode. Conclusion The results of the present study suggest that several risk factors have a crucial role in hip re-fracture time in patients over 65 years old.

Living alone vs. living with someone as a predictor of mortality after a bone fracture in older age

Background Living alone is a risk factor for health decline in old age, especially when facing adverse events increasing vulnerability. Aim We examined whether living alone is associated with higher post-fracture mortality risk. Methods Participants were 190 men and 409 women aged 75 or 80 years at baseline. Subsequent fracture incidence and mortality were followed up for 15 years. Extended Cox regression analysis was used to compare the associations between living arrangements and mortality risk during the first post-fracture year and during the non-fracture time. All participants contributed to the non-fracture state until a fracture occurred or until death/end of follow-up if they did not sustain a fracture. Participants who sustained a fracture during the follow-up returned to the non-fracture state 1 year after the fracture unless they died or were censored due to end of follow-up. Results Altogether, 22% of men and 40% of women sustained a fracture. During the first post-fracture year, mortality risk was over threefold compared to non-fracture time but did not differ by living arrangement. In women, living alone was associated with lower mortality risk during non-fracture time, but the association attenuated after adjustment for self-rated health. In men, living alone was associated with increased mortality risk during non-fracture time, although not significantly. Conclusion The results suggest that living alone is not associated with pronounced mortality risk after a fracture compared to living with someone.