The purpose of this paper is to compare fracture‐fixation and bone‐healing promotion efficacies of an intramedullary (IM) nail‐type and an external osteosynthesis plate‐type femoral trochanteric‐fracture implants using the results of a combined multi‐body dynamics and finite element analyses. For both implants, fracture fixation was obtained using a dynamic hip blade which is anchored to the femur head on one end and is connected to the IM rod/plate on the other. The analysis was carried out for two pre‐fracture conditions of the femur: healthy and osteoporotic.
The musculoskeletal dynamics portion of the analysis was used to obtain realistic physiological loading conditions (i.e. muscle forces and joint reaction forces and moments) associated with four typical everyday activities of a patient, namely, walking, lunging, cycling and egress (i.e. exiting a passenger vehicle). The subsequent structural finite element analysis of the fractured femur/implant assembly was employed to quantify fracture‐fixation efficacy (as measured by the extents of lateral (found to be minor), flexural and torsional displacements of the two femur fragments) and the bone‐healing promotion efficacy (as quantified by the fraction of the fractured surface area which experienced desirable contact pressures).
The results obtained show that, in general, the IM‐rod type of implant out‐performs the osteosynthesis plate type of implant over a large range of scenarios involving relative importance of the bone‐healing promotion and fracture‐fixation efficacies, health condition of the femur and the activity level of the patient. More specifically, the more active the patient and the larger extent of osteoporosis in the femur, the more justifiable is the use of the IM‐rod type of implant.
The present approach enables assessment of the fracture‐fixation performance of orthopedic implants under physiologically realistic loading conditions.
Grujicic, A., LaBerge, M., Xie, X., Arakere, G., Pandurangan, B., Grujicic, M., Jeray, K.J. and Tanner, S.L. (2011), "Computational investigation of the relative efficacies of nail‐ and plate‐type proximal femoral‐fracture fixation implants", Multidiscipline Modeling in Materials and Structures, Vol. 7 No. 3, pp. 212-244. https://doi.org/10.1108/1536-540911178234
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