Importance

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Abstract

A flexible inramedullary fixation rod for fractured bones is provided having a length sufficient to extend a substantial distance on either side of a diaphyseal fracture site and a substantially circular core with radially disposed fins extending substantially along the full length thereof. The radii of the core and fins are such that the rod can pass through the bone's medullary canal and engage the inner, or endosteal, surface of the bone along line contacts, thereby allowing normal endosteal healing and intramedullary revascularization. The rod is constructed of a flexible, bio-compatible material, such as titanium, stainless steel, resorbable polymers (e.g., polylactic acid) or carbon fiber-polysulfone. The radii of the fins are selected to be substantially equal to the minimum radius of the medullary canal. The core radius is selected in accordance with the Young's and shear moduli associated with the bio-compatible material to provide a rod structural rigidity (bending and torsional) preferably between 0.1% and 10% of the inherent bone rigidity with the relationship between the rod bending and torsional rigidities preferably being substantially the same as the corresponding relationship for the intact bone. This causes natural stresses (bending and torsional) to be maintained at the fracture site, thereby promoting natural and therefore stronger healing of the fractured bone.

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First Claim