US5053035A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flexible intramedullary fixation rod
Assignee: Individual
•
Filing: 1990-05-24
•
Granted: 1991-10-01
•
Expires: 2010-05-24
Abstract
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.
Inventors
- 👤 Alexander C. McLaren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:48
CPC Classifications
A; A61; A61B; A61B17/00; A61B17/56; A61B17/58; A61B17/68; A61B17/72; A61B17/7208; A61B17/7283; A61B2017/00004
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
147 words
A flexible intramedullary fixation rod for insertion into a medullary canal of a bone for treating a diaphyseal fracture thereof, said fixation rod comprising: an elongate rod of unitary construction fabricated substantially from a single material and having a bending rigidity B, said rod having: an elongate core having a radial periphery at a core radius distal from the longitudinal axis of said core; and a plurality of fins radially disposed about said core periphery, each of said fins having an outer fin edge which extends substantially parallel to and along said core longitudinal axis at a fin radius R distal from said core longitudinal axis; wherein said core radius and fin radius R are selected to provide said rod with a bending rigidity B within an approximate range according to (0.001)S≦B≦(0.0150)S where: S=(π/4) [(R+T) 4 -R 4 ]E T ε{3 mm, 6 mm } E=20,000 N/mm.sup.2.
Claim 2
Dependent Claim
147 words
A flexible intramedullary fixation rod for insertion into a medullary canal of a bone for treating a diaphyseal fracture thereof, said fixation rod comprising: an elongate rod of unitary construction fabricated substantially from a single material and having a bending rigidity B, said rod having: an elongate core having a radial periphery at a core radius distal from the longitudinal axis of said core; and a plurality of fins radially disposed about said core periphery, each of said fins having an outer fin edge which extends substantially parallel to and along said core longitudinal axis at a fin radius R distal from said core longitudinal axis; wherein said core radius and fin radius R are selected to provide said rod with a bending rigidity B within an approximate range according to (0.001)S≦B≦(0.0150)S where: S=(π/4) [(R+T) 4 -R 4 ]E T ε{3 mm, 6 mm } E=20,000 N/mm.sup.2.
Claim 3
Dependent Claim
41 words
A flexible intramedulary fixation rod as recited in claim 1, wherein said rod has a pointed insertion end and an installation end, and further wherein said fins have substantially triangular cross-sectional areas in a plane normal to said core longitudinal axis.
Claim 4
Dependent Claim
44 words
A flexible intramedullary fixation rod as recited in claim 2, wherein said rod fabrication material comprises titanium, said fin radius R is within the approximate range of 1 mm-11 mm and said core radius is within the approximate range of 0.5 mm -10 mm.
Claim 5
Dependent Claim
46 words
A flexible intramedullary fixation rod as recited in claim 2, wherein said rod fabrication material comprises stainless steel, said fin radius R is within the approximate range of 1 mm -11 mm and said core radius is within the approximate range of 0.5 mm -10 mm.
Claim 6
Dependent Claim
202 words
An improved flexible intramedulary fixation rod for insertion into a medulary canal of a bone for treating a diaphyseal fracture thereof, said rod comprising an elongate member having a maximum radial periphery at a maximum radius allowing said member to be received within said bone medullary canal, and said rod having a length allowing it to extend a substantial distance within said medullary canal on either side of the site of said diaphyseal fracture, said improvement comprising: an elongate rod having unitary construction, fabricated from a single material and having an elongate core which is concentric with the longitudinal axis of said elongate rod; a plurality of fins radially disposed about the periphery of said elongate rod core, each of said fins having an outer fin edge extending substantially parallel to and along said rod longitudinal axis at a fin radius R distal from said rod longitudinal axis at said elongate member maximum radius; and an elongate rod core radius, wherein said core radius and fin radius R are selected to provide said elongate member with a bending rigidity B within an approximate range according to (0.001)S≦B≦(0.150)S where: S=(π/4) [(R+T] 4 -R 4 ]E Tε{3 mm, 6 mm] E=20,000 N/mm 2 .
Claim 7
Dependent Claim
202 words
An improved flexible intramedulary fixation rod for insertion into a medulary canal of a bone for treating a diaphyseal fracture thereof, said rod comprising an elongate member having a maximum radial periphery at a maximum radius allowing said member to be received within said bone medullary canal, and said rod having a length allowing it to extend a substantial distance within said medullary canal on either side of the site of said diaphyseal fracture, said improvement comprising: an elongate rod having unitary construction, fabricated from a single material and having an elongate core which is concentric with the longitudinal axis of said elongate rod; a plurality of fins radially disposed about the periphery of said elongate rod core, each of said fins having an outer fin edge extending substantially parallel to and along said rod longitudinal axis at a fin radius R distal from said rod longitudinal axis at said elongate member maximum radius; and an elongate rod core radius, wherein said core radius and fin radius R are selected to provide said elongate member with a bending rigidity B within an approximate range according to (0.001)S≦B≦(0.150)S where: S=(π/4) [(R+T] 4 -R 4 ]E Tε{3 mm, 6 mm] E=20,000 N/mm 2 .
Claim 8
Dependent Claim
43 words
A flexible intramedullary fixation rod as recited in claim 5, wherein said rod has a pointed insertion end and an installation end, and further wherein said fins have substantially triangular cross-sectional areas in a plane normal to the longitudinal axis of said core.
Claim 9
Dependent Claim
43 words
An improved flexible intramedullary fixation rod as recited in claim 6, wherein said fabrication material comprises titanium, said fin radius R is within the approximate range of 1 mm-11 mm and said core radius is within the approximate range of 0.5 mm-10 mm.
Claim 10
Dependent Claim
46 words
An improved flexible intramedullary fixation rod as recited in claim 6, wherein said rod fabrication material comprises stainless steel, said fin radius R is within the approximate range of 1 mm-11 mm and said core radius is within the approximate range of 0.5 mm -10 mm.
Claim 11
Independent Claim
199 words
A method for treating a diaphyseal fracture of a bone having an intramedullary canal, said method comprising the steps of: determining the radius of an intramedullary canal of a bone having a diaphyseal fracture; determining the bending rigidity of said bone; selecting a flexible intramedullary fixation rod of unitary construction, fabricated from a single material and having a bending rigidity B, said rod comprising a plurality of fins radially disposed about the periphery of a concentric elongate core, each of said fins having an outer fin edge extending substantially parallel to, along and distal from the longitudinal axis of said concentric elongate core at a fin radius R which is substantially equal to but less than said measured intramedullary canal radius, and said concentric elongate core periphery having a core radius, wherein said core radius and fin radius R are selected to provide said rod with a bending rigidity B within an approximate range according to (0.001)S≦B≦(0.150)S where: S=(π/4) [(R+T) 4 -R 4 ]E Tε{3 mm, 6 mm } E=20,000 N/mm 2 ; and implanting said flexible intramedullary fixation rod into said medullary canal such that said rod extends a substantial distance on either side of said diaphyseal fracture.
Claim 12
Independent Claim
199 words
A method for treating a diaphyseal fracture of a bone having an intramedullary canal, said method comprising the steps of: determining the radius of an intramedullary canal of a bone having a diaphyseal fracture; determining the bending rigidity of said bone; selecting a flexible intramedullary fixation rod of unitary construction, fabricated from a single material and having a bending rigidity B, said rod comprising a plurality of fins radially disposed about the periphery of a concentric elongate core, each of said fins having an outer fin edge extending substantially parallel to, along and distal from the longitudinal axis of said concentric elongate core at a fin radius R which is substantially equal to but less than said measured intramedullary canal radius, and said concentric elongate core periphery having a core radius, wherein said core radius and fin radius R are selected to provide said rod with a bending rigidity B within an approximate range according to (0.001)S≦B≦(0.150)S where: S=(π/4) [(R+T) 4 -R 4 ]E Tε{3 mm, 6 mm } E=20,000 N/mm 2 ; and implanting said flexible intramedullary fixation rod into said medullary canal such that said rod extends a substantial distance on either side of said diaphyseal fracture.
Claim 13
Independent Claim
212 words
A method for treating a diaphyseal fracture of a bone having an intramedulary canal, said bone having inherent bending and torsional rigidities prior to said fracture thereof, said method comprising the steps of: determining the radius of said intramedullary canal; determining the inherent bending and torsional rigidities of said bone; selecting a flexible intramedullary fixation rod of unitary construction fabricated from a single material, said rod comprising a plurality of fins radially disposed about the periphery of a concentric core, said fins having outer fin edges extending substantially parallel to and along said rod longitudinal axis at respective fin radii distal from said core longitudinal axis, wherein said fin radii are substantially equal to but less than said measured intramedullary canal radius, and wherein said periphery of said concentric core has a radius selected to provide said fixation rod with bending and torsional rigidities which are less than said inherent bone bending and torsional rigidities, respectively, and further wherein the ratio of said rod bending rigidity to said inherent bone bending rigidity is substantially equal to the ratio of said rod torsional rigidity to said inherent bone torsional rigidity; and implanting said rod into said medullary canal such that said rod extends a substantial distance on either side of said diaphyseal fracture.
Claim 14
Independent Claim
212 words
A method for treating a diaphyseal fracture of a bone having an intramedulary canal, said bone having inherent bending and torsional rigidities prior to said fracture thereof, said method comprising the steps of: determining the radius of said intramedullary canal; determining the inherent bending and torsional rigidities of said bone; selecting a flexible intramedullary fixation rod of unitary construction fabricated from a single material, said rod comprising a plurality of fins radially disposed about the periphery of a concentric core, said fins having outer fin edges extending substantially parallel to and along said rod longitudinal axis at respective fin radii distal from said core longitudinal axis, wherein said fin radii are substantially equal to but less than said measured intramedullary canal radius, and wherein said periphery of said concentric core has a radius selected to provide said fixation rod with bending and torsional rigidities which are less than said inherent bone bending and torsional rigidities, respectively, and further wherein the ratio of said rod bending rigidity to said inherent bone bending rigidity is substantially equal to the ratio of said rod torsional rigidity to said inherent bone torsional rigidity; and implanting said rod into said medullary canal such that said rod extends a substantial distance on either side of said diaphyseal fracture.
References Cited (Backward Citations)
DE757951C
Cited
US2518019A
Cited
US3208450A
Cited
US3463158A
Cited
US3739773A
Cited
US3530854A
Cited
US3678925A
Cited
US3709218A
Cited
US3893196A
Cited
US3716051A
Cited
US3717146A
Cited
US3760802A
Cited
US3763855A
Cited
US3892233A
Cited
US3783860A
Cited
FR2221111A1
Cited
US4055172A
Cited
AU480652A
Cited
US3990438A
Cited
US3977398A
Cited
US4091806A
Cited
US4281649A
Cited
US4135507A
Cited
US4103683A
Cited
US4169470A
Cited
US4204531A
Cited
US4227518A
Cited
US4446579A
Cited
US4237875A
Cited
US4212294A
Cited
US4275717A
Cited
WO1981001647A1
Cited
US4313434A
Cited
US4522202A
Cited
US4473069A
Cited
US4541424A
Cited
US4457301A
Cited
US4452973A
Cited
US4475545A
Cited
US4574795A
Cited
US4621628A
Cited
US4628920A
Cited
US4705027A
Cited
US4875475A
Cited
US4697585A
Cited
US4667664A
Cited
US4632101A
Cited
US4622959A
Cited
US4858602A
Cited
US4776330A
Cited
US4877019A
Cited
US4827917A
Cited
US4756307A
Cited
US4846162A
Cited
US4805607A
Cited
US4875474A
Cited
US4854312A
Cited
US4881535A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-30 | 1995-04-01 | 1995-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-30 | 1999-04-01 | 1999-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-30 | 2003-04-01 | 2003-10-01 | $7700.00 | Window Closed / Lapsed |