Biomaterial Database

Intramedullary nails: some design features of the distal end. 2003

C J Wang, and C J Brown, and A L Yettram, and P Procter

Department of Mechanical Engineering, Brunel University, UB8 3PH, Uxbridge, Middlesex, UK.

Intramedullary nails are used to stabilise fractures of the proximal femur. The nail acts by transferring loads from the proximal fraction to the rest of the femoral shaft. The way in which this occurs depends to a large extent on the design of the distal end of the nail. This is not dissimilar to the situation with regard to load shedding (or load transfer) from the femoral component of a total hip replacement. A finite element model of a fractured femur with either a neck or a subtrochanteric fracture is set up to investigate the effects of nail length, nail distal stiffness and material stiffness on the structural behaviour of the system. Specifically what is considered is the influence of these parameters on the stress across the fracture and the normal pressure that the nail exerts on the endosteum of the femoral diaphysis. It is found that a longer nail could produce higher contact stress between the tip of the nail and the endosteum. Also, this contact stress is reduced when the distal region of the nail is made more flexible either by incorporating longitudinal slots or by using a material with a lower modulus of elasticity.

UI	MeSH Term	Description	Entries
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D011312	Pressure	A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Pressures
D011474	Prosthesis Design	The plan and delineation of prostheses in general or a specific prosthesis.	Design, Prosthesis,Designs, Prosthesis,Prosthesis Designs
D001858	Bone Nails	Rods of bone, metal, or other material used for fixation of the fragments or ends of fractured bones.	Bone Pins,Bone Nail,Bone Pin,Nail, Bone,Nails, Bone,Pin, Bone,Pins, Bone
D003198	Computer Simulation	Computer-based representation of physical systems and phenomena such as chemical processes.	Computational Modeling,Computational Modelling,Computer Models,In silico Modeling,In silico Models,In silico Simulation,Models, Computer,Computerized Models,Computer Model,Computer Simulations,Computerized Model,In silico Model,Model, Computer,Model, Computerized,Model, In silico,Modeling, Computational,Modeling, In silico,Modelling, Computational,Simulation, Computer,Simulation, In silico,Simulations, Computer
D004548	Elasticity	Resistance and recovery from distortion of shape.
D005264	Femoral Fractures	Fractures of the femur.	Femoral Fracture,Fracture, Femoral,Fractures, Femoral
D012680	Sensitivity and Specificity	Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)	Specificity,Sensitivity,Specificity and Sensitivity
D013314	Stress, Mechanical	A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.	Mechanical Stress,Mechanical Stresses,Stresses, Mechanical
D015203	Reproducibility of Results	The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.	Reliability and Validity,Reliability of Result,Reproducibility Of Result,Reproducibility of Finding,Validity of Result,Validity of Results,Face Validity,Reliability (Epidemiology),Reliability of Results,Reproducibility of Findings,Test-Retest Reliability,Validity (Epidemiology),Finding Reproducibilities,Finding Reproducibility,Of Result, Reproducibility,Of Results, Reproducibility,Reliabilities, Test-Retest,Reliability, Test-Retest,Result Reliabilities,Result Reliability,Result Validities,Result Validity,Result, Reproducibility Of,Results, Reproducibility Of,Test Retest Reliability,Validity and Reliability,Validity, Face