WO1995014176A1 - Self-locking set screw for spinal fixation system - Google Patents
Self-locking set screw for spinal fixation system Download PDFInfo
- Publication number
- WO1995014176A1 WO1995014176A1 PCT/US1994/013316 US9413316W WO9514176A1 WO 1995014176 A1 WO1995014176 A1 WO 1995014176A1 US 9413316 W US9413316 W US 9413316W WO 9514176 A1 WO9514176 A1 WO 9514176A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- set screw
- rod
- screw
- frustoconical
- frustoconical portion
- Prior art date
Links
- 239000007943 implant Substances 0.000 claims description 21
- 210000000988 bone and bone Anatomy 0.000 claims description 6
- 229910001220 stainless steel Inorganic materials 0.000 claims description 4
- 239000010935 stainless steel Substances 0.000 claims description 4
- 230000000399 orthopedic effect Effects 0.000 claims description 3
- 238000005299 abrasion Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000002513 implantation Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000001356 surgical procedure Methods 0.000 description 2
- 206010058907 Spinal deformity Diseases 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 210000003205 muscle Anatomy 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 206010039722 scoliosis Diseases 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
- A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
- A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
- A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
- A61B17/70—Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
- A61B17/7001—Screws or hooks combined with longitudinal elements which do not contact vertebrae
- A61B17/7032—Screws or hooks with U-shaped head or back through which longitudinal rods pass
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B35/00—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws
- F16B35/005—Set screws; Locking means therefor
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
- A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
- A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
- A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
- A61B17/84—Fasteners therefor or fasteners being internal fixation devices
- A61B17/86—Pins or screws or threaded wires; nuts therefor
Definitions
- the invention pertains generally to orthopedic implants and more particularly to a low-abrasion set screw for use with a spinal fixation system.
- the implant should provide rigidity as indicated, generally along the long axis of the patient's spine.
- the system should be able to accommodate a broad variation in the size of the spinal member with which it is used; for example, a surgeon may wish to use the implant on a variety of individuals.
- the difference in the area and size of the point of fixation is compounded by the change in the shape of the vertebrae over the length of the full spinal column. Since it is an advantage to allow the surgeon to master implanting a particular type of assembly, it is preferable if the same or similar anchoring means can be used for a variety of locations. This advantage results in cost efficiency of inventory as well as efficiencies with respect to minimiz ⁇ ing operating time.
- the hardware must be able to apply and oppose considerable stresses and strains.
- the anchor means must be securely fixed to the bone, and the stabilizer must be securely fixed with regard to the anchor means.
- the system should be designed for ease of implantation and removal.
- Implant hardware is relatively small and therefore somewhat difficult to manipulate. Any difficulty with assembly is compounded by the fact that the assembly occurs during surgery and in a living being. Therefore, it is critical that the hardware is designed with the surgeon's convenience in mind, i.e., to limit the time required and the stress required to implant an assembly. Consequently, a fixation system should be designed, to the extent possible, for easy assembly while maintaining the option of removal when necessary.
- the invention is directed toward a set screw for orthopedic implant components which is self-locking and exhibits improved holding power under cyclic loading.
- the set screw generally includes an externally threaded cylindrical portion and an integrally attached multi- faceted, tapered portion having a generally frustoconical shape.
- the large-diameter base of the multi-faceted frustoconical portion is coextensive with and integrally attached to one end of the cylindrical portion of the set screw.
- the small base of the multi-faceted frustoconical portion of the set screw includes a conical recess having an axis which is generally coincident with the axes of the cylindrical and frustoconical portions of the set screw, and having a base which is substantially coincident with the small-diameter base of the frustoconical portion such that the internal surface of the conical recess, together with the external surfaces of adjacent facets of the frustoconical portion, define a plurality of projecting point contacts which are substantially uniformly disposed about the axis of the set screw in a plane perpendicular to the axis of the set screw.
- the set screw has a hardness which is greater than that of the rod which it engages.
- the set screw of the invention is generally used in association with a rod-holding member having a rod- receiving channel and a threaded bore perpendicular to and in communication with the rod-receiving channel.
- the rod- holding members can be rod connectors or can be anchored to the bones which are to be fixed relative to one another by the spinal fixation system.
- spinal fixation is achieved by retaining one or more rods in fixed relationship to at least a pair of rod-holding members which are anchored to the bones which are to be held in a relative position.
- Fixation of the rods rela ⁇ tive to the rod-holding members can be achieved by screw- ing a set screw into the threaded bore of the rod-holding member and engaging the outer circumferential surface of a rod received within the rod-receiving channel of the rod-holding member.
- the plurality of circularly disposed sharp point contacts engage the outer radial surface of the rod as the screw is tightened thereby cutting or biting into the outer surface of the rod with the plurality of points to lock the screw into position relative to the rod and rod- holding member while reducing the amount of abrasion, thereby also reducing the amount of wear debris generated during the fixation procedure.
- the screw is harder than the rod to facilitate the compressive grip on the rod to protect the screw threads and to minimize wear debris from the screw.
- the set screw of the present invention also has application for rod connectors and rod linking members.
- Figure 1 is a side view of the set screw in accordance with the invention.
- Figure 2 is a top view of the set screw
- Figure 3 is a cross section of the set screw taken along line 3-3 shown in Figure 2;
- Figure 4 is a bottom view of the set screw
- Figure 5 is an exploded side view of a spinal implant assembly utilizing the set screw in accordance with the invention.
- Figure 6 is a front exploded view of the spinal implant assembly
- Figure 7 is a cross section of the spinal implant assembly taken along line 6-6 of Figure 5;
- Figure 8 is a cross section of the spinal implant assembly taken along line 7-7 of Figure 4;
- Figure 9 is a top view of a rod connector utilizing the set screw of the present invention.
- Figure 10 is a cross section of a rod connector shown in Figure 8, and
- Figure 11 is a front view of the rod connector shown in Figure 8.
- FIGS 1-3 illustrate the set screw member 49 in accordance with the invention.
- the screw 10 has an internal hex 20 which allows the set screw to be screwed with the seat 12.
- the set screw includes an externally threaded cylindrical portion 25 and a tapered or frustoconical-shaped portion 30 integrally attached there ⁇ to.
- the large base of the frustoconical portion is substantially coextensive with and integrally attached to one end of the cylindrical portion.
- the dimensions of the small-diameter base of the frustoconical portion of the set screw is not critical but is typically about one-half of the diameter of the large base of the frustoconical portion.
- the distance from the large-diameter base to the small-diameter base of the frustoconical portion is not critical, but is generally from about 20 percent to about
- the frustoconical portion of the set screw has a plurality of facets 35 or surfaces connecting the large- diameter base with the small-diameter base.
- Each of the facets is preferably a trapezoidal shape which together form a repeating pattern of peaks and valleys about the peripheral frustoconical surface.
- a generally conically shaped hollow 38 or recess having an axis coincident with the axes of the cylindrical and frustoconical portions of the set screw is provided at the small-diameter base of the frustoconical portion.
- the internal surface of the recess, together with the external surfaces of adjacent facets of the frustoconical portion, provide a plurality of pointed contacts 39 which are rela ⁇ tively uniformly radially disposed about the central axis of the set screw in a circular pattern perpendicular to the axis of the set screw.
- the assembly is shown in general at 40, and comprises anchor member 41 which includes seat means 42 and fixation means 44 which, in the present case, comprise a screw. It is envisioned that a vertebral hook could be used instead of a screw.
- the seat means 42 includes an upper bevel 43 to eliminate edges which interface with the patient's muscle. Additionally, the seat 42 has a rod channel 47 which receives a rod 51. The seat means 42 has a tapered area 41 which forms a bone interface area. The seat means 42 further includes a bore 48, which is substantially perpen- dicular to the rod-receiving channel 47. The bore 48 includes internal threads 52 which mate with the external threads 56 of a set screw member 49.
- the set screw has a hardness greater than that of the rod so that when the set screw is screwed into the internally threaded bore 48, the point contacts cut or bite into the rod 51 thereby applying compressive forces to the rod to hold the rod in fixed relation to the seat means 12 and to lock the set screw into position.
- the plurality of point contacts of the set screw reduce the amount of contact between the set screw and the rod thereby reducing abrasion and .consequently reducing the amount of wear debris generated during the fixation procedure.
- the set screw has a hardness differential from the rod of between 5 to 20 Rockwell points on the C-Scale.
- Spinal implant systems must be made of a material which has been approved for implantation and has the characteristics which are desir ⁇ able for an implant.
- Stainless steel is traditionally used for all parts of the implant system.
- the rod is made of 316L stainless steel with a Rockwell Hardness on the C-Scale of from about 34 to about 36.
- the components which are used in conjunction with the rod must be compatible with the rod.
- An acceptable material for the screw is 22-13-5-SS (stainless steel) . This material is subsequently cold worked in order to achieve a Rockwell Hardness on the C-Scale of at least 40.
- a more desirable range of differentiation is from about 12 to about 15 points RHC between the rod and the screw.
- the contact between the set screw and the rod be provided by a plural ⁇ ity of points rather than a continuous circular ridge.
- the recess at the small-radius base of the frustoconical portion of the set screw is preferably conical, as shown.
- various other recesses can be provided such as a frustoconical recess, so long as a plurality of pointed contacts are provided.
- the angle of the facets defining the frustoconi ⁇ cal surface relative to the axis of the cylindrical portion is generally in the range from about 30° to about 60° and preferably in the range from about 45° to about 55°.
- the angle of the conical recess relative to the longitudinal axis of the set screw is generally in the range from about 45° to about 75° and preferably from about 55° to about 65°.
- the rod channel 47 can include one or preferably a plurality of serrations 58 which extend from about 60° to about 120° about the channel.
- the serrations include an interruption or cross-channel 59 which provides lateral edge areas 60 which hold the rod 51 against translational rotation about its longitudinal axis.
- the set screw can be used with an axial rod connector.
- the axial connector 70 includes connector seat means 72 having an internal bore 76 and including rod-receiving channels 77.
- the bore 76 includes an intermediate neck portion which forms rod abutments 78 which form a positive stop for the end of the rod.
- the axial connector includes the set screws of the invention which can be advantageously aligned along the longitudinal axis of the rod.
- the axial connector can include a plurality of serrations 88 which are interrupted as set forth hereinabove so as to inhibit both rotational and axial misalignment or movement.
- the spinal fixation system can as shown in FIGS. 14-16, comprise a parallel connector 100.
- the parallel connector includes connector seat means 102 having parallel rod channels 107.
- the rod channels include substantially perpendicular set screws 109 which receive set screws as previously illustrated which apply a compressive force to a rod, to bias the rod into contact with interrupted serrations 118, as previously discussed.
- the parallel connector includes indentations 103 for a connector holder for ease of insertion.
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- Health & Medical Sciences (AREA)
- Orthopedic Medicine & Surgery (AREA)
- Engineering & Computer Science (AREA)
- Neurology (AREA)
- General Engineering & Computer Science (AREA)
- Surgery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Heart & Thoracic Surgery (AREA)
- Biomedical Technology (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Mechanical Engineering (AREA)
- Surgical Instruments (AREA)
- Prostheses (AREA)
Abstract
A set screw (10) for exerting compressive forces between a rod-holding member and a rod (51) of a spinal fixation system to hold the components thereof together in fixed relationship to each other. The screw (10) includes an externally threaded cylindrical portion (25) having at one end an internal hex (20) for allowing the set screw (10) to be screwed into contact with a rod (51) contained within a rod-receiving channel (47) of a rod-holding member, and a frustoconical portion (30) having a large radius base which is coextensive with and integrally attached to the other end of the cylindrical portion (25) of the set screw (10). The frustoconical portion (30) has a multi-faceted external surface (35) and has an internal recess (36) at its small radius base. The internal surface of the recess (36), together with the external surfaces of adjacent facets (35), forms a plurality of point contacts (39) disposed radially about the axis of the set screw (10) in a plane perpendicular to the axis of the set screw (10). The set screw (10) is harder than the rod (51).
Description
SELF-LOCKING SET SCREW FOR SPINAL FIXATION SYSTEM
FIELD OF INVENTION The invention pertains generally to orthopedic implants and more particularly to a low-abrasion set screw for use with a spinal fixation system.
BACKGROUND As surgical techniques have advanced, it has become increasingly common for surgeons to use specially designed hardware for the internal fixation of bones. A particular area of concentration for the recent develop¬ ment of this technology has been the spine. Internal fixation is used most frequently in the spine in conjunc- tion with vertebral fusion, and also for the manipulation of the spine to correct spinal deformities, such as scoliosis.
There are several important criteria for a hardware system which is used internally for spinal fixation:
1. . The implant should provide rigidity as indicated, generally along the long axis of the patient's spine.
2. The system should be able to accommodate a broad variation in the size of the spinal member with which it is used; for example, a surgeon may wish to use the implant on a variety of individuals. In addition, the difference in the area and size of the point of fixation is compounded by the change in the shape of the vertebrae over the length of the full spinal column. Since it is an advantage to allow the surgeon to master implanting a particular type of assembly, it is preferable if the same or similar anchoring means can be used for a variety of locations. This advantage results in cost efficiency of inventory as well as efficiencies with respect to minimiz¬ ing operating time.
3. The hardware must be able to apply and oppose considerable stresses and strains. Thus,, the anchor means must be securely fixed to the bone, and the
stabilizer must be securely fixed with regard to the anchor means. Moreover, it is desirable to provide the hardware with the integrity to resist to breaking.
4. The system should be designed for ease of implantation and removal. Implant hardware is relatively small and therefore somewhat difficult to manipulate. Any difficulty with assembly is compounded by the fact that the assembly occurs during surgery and in a living being. Therefore, it is critical that the hardware is designed with the surgeon's convenience in mind, i.e., to limit the time required and the stress required to implant an assembly. Consequently, a fixation system should be designed, to the extent possible, for easy assembly while maintaining the option of removal when necessary.
SUMMARY OF THE INVENTION The invention is directed toward a set screw for orthopedic implant components which is self-locking and exhibits improved holding power under cyclic loading. The set screw generally includes an externally threaded cylindrical portion and an integrally attached multi- faceted, tapered portion having a generally frustoconical shape. The large-diameter base of the multi-faceted frustoconical portion is coextensive with and integrally attached to one end of the cylindrical portion of the set screw. The small base of the multi-faceted frustoconical portion of the set screw includes a conical recess having an axis which is generally coincident with the axes of the cylindrical and frustoconical portions of the set screw, and having a base which is substantially coincident with the small-diameter base of the frustoconical portion such that the internal surface of the conical recess, together with the external surfaces of adjacent facets of the frustoconical portion, define a plurality of projecting point contacts which are substantially uniformly disposed about the axis of the set screw in a plane perpendicular to the axis of the set screw. In accordance with the
principles of the invention the set screw has a hardness which is greater than that of the rod which it engages. The set screw of the invention is generally used in association with a rod-holding member having a rod- receiving channel and a threaded bore perpendicular to and in communication with the rod-receiving channel. The rod- holding members can be rod connectors or can be anchored to the bones which are to be fixed relative to one another by the spinal fixation system. In many implant systems, spinal fixation is achieved by retaining one or more rods in fixed relationship to at least a pair of rod-holding members which are anchored to the bones which are to be held in a relative position. Fixation of the rods rela¬ tive to the rod-holding members can be achieved by screw- ing a set screw into the threaded bore of the rod-holding member and engaging the outer circumferential surface of a rod received within the rod-receiving channel of the rod-holding member.
In accordance with the principles of the inven- tion, the plurality of circularly disposed sharp point contacts engage the outer radial surface of the rod as the screw is tightened thereby cutting or biting into the outer surface of the rod with the plurality of points to lock the screw into position relative to the rod and rod- holding member while reducing the amount of abrasion, thereby also reducing the amount of wear debris generated during the fixation procedure. Moreover, the screw is harder than the rod to facilitate the compressive grip on the rod to protect the screw threads and to minimize wear debris from the screw. The set screw of the present invention also has application for rod connectors and rod linking members.
BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a side view of the set screw in accordance with the invention;
Figure 2 is a top view of the set screw;
Figure 3 is a cross section of the set screw taken along line 3-3 shown in Figure 2;
Figure 4 is a bottom view of the set screw;
Figure 5 is an exploded side view of a spinal implant assembly utilizing the set screw in accordance with the invention;
Figure 6 is a front exploded view of the spinal implant assembly;
Figure 7 is a cross section of the spinal implant assembly taken along line 6-6 of Figure 5;
Figure 8 is a cross section of the spinal implant assembly taken along line 7-7 of Figure 4;
Figure 9 is a top view of a rod connector utilizing the set screw of the present invention; Figure 10 is a cross section of a rod connector shown in Figure 8, and
Figure 11 is a front view of the rod connector shown in Figure 8.
DETAILED DESCRIPTION OF INVENTION
Figures 1-3 illustrate the set screw member 49 in accordance with the invention. The screw 10 has an internal hex 20 which allows the set screw to be screwed with the seat 12. The set screw includes an externally threaded cylindrical portion 25 and a tapered or frustoconical-shaped portion 30 integrally attached there¬ to. The large base of the frustoconical portion is substantially coextensive with and integrally attached to one end of the cylindrical portion. The dimensions of the small-diameter base of the frustoconical portion of the set screw is not critical but is typically about one-half of the diameter of the large base of the frustoconical portion. The distance from the large-diameter base to the small-diameter base of the frustoconical portion is not critical, but is generally from about 20 percent to about
30 percent of the axial length of the cylindrical portion.
The frustoconical portion of the set screw has
a plurality of facets 35 or surfaces connecting the large- diameter base with the small-diameter base. Each of the facets is preferably a trapezoidal shape which together form a repeating pattern of peaks and valleys about the peripheral frustoconical surface.
A generally conically shaped hollow 38 or recess having an axis coincident with the axes of the cylindrical and frustoconical portions of the set screw is provided at the small-diameter base of the frustoconical portion. The internal surface of the recess, together with the external surfaces of adjacent facets of the frustoconical portion, provide a plurality of pointed contacts 39 which are rela¬ tively uniformly radially disposed about the central axis of the set screw in a circular pattern perpendicular to the axis of the set screw.
A spinal implant assembly suitable for use with the set screw of the invention is illustrated in FIGS. 4- 7.
The assembly is shown in general at 40, and comprises anchor member 41 which includes seat means 42 and fixation means 44 which, in the present case, comprise a screw. It is envisioned that a vertebral hook could be used instead of a screw.
The seat means 42 includes an upper bevel 43 to eliminate edges which interface with the patient's muscle. Additionally, the seat 42 has a rod channel 47 which receives a rod 51. The seat means 42 has a tapered area 41 which forms a bone interface area. The seat means 42 further includes a bore 48, which is substantially perpen- dicular to the rod-receiving channel 47. The bore 48 includes internal threads 52 which mate with the external threads 56 of a set screw member 49.
In accordance with the principles of the inven¬ tion, the set screw has a hardness greater than that of the rod so that when the set screw is screwed into the internally threaded bore 48, the point contacts cut or bite into the rod 51 thereby applying compressive forces
to the rod to hold the rod in fixed relation to the seat means 12 and to lock the set screw into position. The plurality of point contacts of the set screw reduce the amount of contact between the set screw and the rod thereby reducing abrasion and .consequently reducing the amount of wear debris generated during the fixation procedure.
It is a particular advantage that the set screw has a hardness differential from the rod of between 5 to 20 Rockwell points on the C-Scale. Spinal implant systems must be made of a material which has been approved for implantation and has the characteristics which are desir¬ able for an implant. Stainless steel is traditionally used for all parts of the implant system. Customarily, the rod is made of 316L stainless steel with a Rockwell Hardness on the C-Scale of from about 34 to about 36. The components which are used in conjunction with the rod must be compatible with the rod. An acceptable material for the screw is 22-13-5-SS (stainless steel) . This material is subsequently cold worked in order to achieve a Rockwell Hardness on the C-Scale of at least 40. Thus a more desirable range of differentiation is from about 12 to about 15 points RHC between the rod and the screw.
Important to the invention is that the contact between the set screw and the rod be provided by a plural¬ ity of points rather than a continuous circular ridge.
For convenience of machining, the recess at the small-radius base of the frustoconical portion of the set screw is preferably conical, as shown. However, various other recesses can be provided such as a frustoconical recess, so long as a plurality of pointed contacts are provided.
The angle of the facets defining the frustoconi¬ cal surface relative to the axis of the cylindrical portion is generally in the range from about 30° to about 60° and preferably in the range from about 45° to about 55°.
The angle of the conical recess relative to the longitudinal axis of the set screw is generally in the range from about 45° to about 75° and preferably from about 55° to about 65°. The rod channel 47 can include one or preferably a plurality of serrations 58 which extend from about 60° to about 120° about the channel. In addition, the serrations include an interruption or cross-channel 59 which provides lateral edge areas 60 which hold the rod 51 against translational rotation about its longitudinal axis.
In accordance with another embodiment of the invention as shown in FIG. 8, the set screw can be used with an axial rod connector. The axial connector 70 includes connector seat means 72 having an internal bore 76 and including rod-receiving channels 77. The bore 76 includes an intermediate neck portion which forms rod abutments 78 which form a positive stop for the end of the rod. In addition, the axial connector includes the set screws of the invention which can be advantageously aligned along the longitudinal axis of the rod. The axial connector can include a plurality of serrations 88 which are interrupted as set forth hereinabove so as to inhibit both rotational and axial misalignment or movement. In accordance with an additional embodiment, the spinal fixation system can as shown in FIGS. 14-16, comprise a parallel connector 100. The parallel connector includes connector seat means 102 having parallel rod channels 107. The rod channels include substantially perpendicular set screws 109 which receive set screws as previously illustrated which apply a compressive force to a rod, to bias the rod into contact with interrupted serrations 118, as previously discussed. Additionally, the parallel connector includes indentations 103 for a connector holder for ease of insertion.
While in accordance with the patent statutes the best mode and preferred embodiment has been set forth, the
scope of the invention is not limited thereto, but rather by the scope of the attached claims.
Claims
WHAT IS CLAIMED ISt
1. A set screw for use with orthopedic im¬ plants, said set screw comprising: an externally threaded cylindrical portion having means at one end for driving said set screw, a multi-faceted generally frustoconical shaped portion having a larger base which is coincident with and integrally attached to the other end of said cylindrical portion, said frustoconical portion having a small radius base provided with a recess having an internal surface which, together with adjacent pairs of the surfaces of said facets of said frustoconical portion, define a plurality of sharp point contacts.
2. The set screw of Claim 1, wherein the means for driving the set screw is an internal hexagonal shaped recess.
3. The set screw of Claim 1, wherein the multi- faceted frustoconical portion of said set screw is com¬ prised of a plurality of facets extending from the large- diameter base to the small-diameter base of said frustoconical portion.
4. The set screw of Claim 1, wherein the facets of said multi-faceted frustoconical portion each form an angle of from about 30° to about 60° with the axis of said set screw.
5. The set screw of Claim 1, wherein the facets of said multi-faceted frustoconical portion each form an angle of from about 45° to about 55° with the axis of said set screw.
6. The set screw of Claim 4, wherein the conical recess in the vicinity of the point contacts forms
- lo ¬
an angle with the longitudinal axis of said set screw of from about 45° to about 75°.
7. The set screw of Claim 4, wherein the conical recess in the vicinity of the point contacts forms an angle with the longitudinal axis of said set screw of from about 55° to about 65°.
8. The set screw of Claim 1, wherein said set screw has a hardness of at least 40 on the Rockwell
Hardness C-Scale.
9. The set screw of Claim 8, wherein said set screw is made from 22-13-5-SS.
10. A set screw as set forth in Claim 1, wherein said set screw is cold-worked.
11. A spinal implant comprising a rod and at least two rod holding means, said rod holding means comprising a rod seat and a set screw having an externally threaded cylindrical portion having means at one end for driving said set screw and a multi-faceted generally frustoconical shaped portion having a larger base which is coincident with and integrally attached to the other end of said cylindrical portion, said frustoconical portion having a small radius base provided with a recess having an internal surface which together with adjacent pairs of the surfaces of said facets of said frustoconical portion, define a plurality of sharp point contacts.
12. A spinal implant as set forth in claim 11, wherein said set screw is from 12 to 15 units on the Rockwell Hardness C-Scale harder than said rod.
lS. A spinal implant as set forth in claim 12, wherein said rod is made from 316L stainless steel and said screw is made from 22-13-5-SS.
14. A spinal implant as set forth in claim 13, wherein said screw is cold-worked.
15. A spinal implant as set forth in claim 14, wherein said rod holding means is an anchor which is secured to a bone.
16. A spinal implant as set forth in claim 11, wherein said rod holding means is a connector.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU12908/95A AU1290895A (en) | 1993-11-19 | 1994-11-17 | Self-locking set screw for spinal fixation system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15498493A | 1993-11-19 | 1993-11-19 | |
US08/154,984 | 1993-11-19 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995014176A1 true WO1995014176A1 (en) | 1995-05-26 |
Family
ID=22553655
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1994/013316 WO1995014176A1 (en) | 1993-11-19 | 1994-11-17 | Self-locking set screw for spinal fixation system |
Country Status (2)
Country | Link |
---|---|
AU (1) | AU1290895A (en) |
WO (1) | WO1995014176A1 (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0784967A2 (en) * | 1996-01-19 | 1997-07-23 | Howmedica GmbH | Spine implant |
WO1998005262A1 (en) * | 1996-08-07 | 1998-02-12 | Bioprot, S.A. | Improvements to devices for fixing and correcting dorsal vertebrae |
US5891129A (en) * | 1997-02-28 | 1999-04-06 | Abbott Laboratories | Container cap assembly having an enclosed penetrator |
US6695829B2 (en) | 1996-04-22 | 2004-02-24 | Abbott Laboratories | Container closure system |
ES2304817A1 (en) * | 2005-02-11 | 2008-10-16 | Implant Microdent System, S.L. | Orthodontic implant (Machine-translation by Google Translate, not legally binding) |
EP2016916A1 (en) * | 2007-07-20 | 2009-01-21 | BIEDERMANN MOTECH GmbH | Bone anchoring device |
WO2019013916A1 (en) * | 2017-07-10 | 2019-01-17 | American Sterilizer Company | Brake screw for surgical lighting systems |
US10758280B2 (en) | 2017-10-09 | 2020-09-01 | Acumed Llc | System and method for bone fixation using a nail locked to an encircling anchor |
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US5073074A (en) * | 1990-07-26 | 1991-12-17 | Sps Technologies, Inc. | Set screw |
US5129388A (en) * | 1989-02-09 | 1992-07-14 | Vignaud Jean Louis | Device for supporting the spinal column |
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- 1994-11-17 AU AU12908/95A patent/AU1290895A/en not_active Abandoned
- 1994-11-17 WO PCT/US1994/013316 patent/WO1995014176A1/en active Application Filing
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US2201087A (en) * | 1938-04-28 | 1940-05-14 | Standard Pressed Steel Co | Self-locking setscrew |
US2553337A (en) * | 1948-09-21 | 1951-05-15 | Julius E Shafer | Bearing assembly |
US3143029A (en) * | 1960-03-28 | 1964-08-04 | Set Screw & Mfg Company | Set screw with center of gravity located to permit orientation |
US5005562A (en) * | 1988-06-24 | 1991-04-09 | Societe De Fabrication De Material Orthopedique | Implant for spinal osteosynthesis device, in particular in traumatology |
US5129388A (en) * | 1989-02-09 | 1992-07-14 | Vignaud Jean Louis | Device for supporting the spinal column |
US5073074A (en) * | 1990-07-26 | 1991-12-17 | Sps Technologies, Inc. | Set screw |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0784967A2 (en) * | 1996-01-19 | 1997-07-23 | Howmedica GmbH | Spine implant |
EP0784967A3 (en) * | 1996-01-19 | 1998-03-18 | Howmedica GmbH | Spine implant |
US6019760A (en) * | 1996-01-19 | 2000-02-01 | Howmedica Gmbh | Spine implant |
US6695829B2 (en) | 1996-04-22 | 2004-02-24 | Abbott Laboratories | Container closure system |
WO1998005262A1 (en) * | 1996-08-07 | 1998-02-12 | Bioprot, S.A. | Improvements to devices for fixing and correcting dorsal vertebrae |
ES2110920A2 (en) * | 1996-08-07 | 1998-02-16 | Bioprot S A | Improvements to devices for fixing and correcting dorsal vertebrae |
US5891129A (en) * | 1997-02-28 | 1999-04-06 | Abbott Laboratories | Container cap assembly having an enclosed penetrator |
US5954104A (en) * | 1997-02-28 | 1999-09-21 | Abbott Laboratories | Container cap assembly having an enclosed penetrator |
ES2304817A1 (en) * | 2005-02-11 | 2008-10-16 | Implant Microdent System, S.L. | Orthodontic implant (Machine-translation by Google Translate, not legally binding) |
EP2016916A1 (en) * | 2007-07-20 | 2009-01-21 | BIEDERMANN MOTECH GmbH | Bone anchoring device |
EP2135573A1 (en) * | 2007-07-20 | 2009-12-23 | Biedermann Motech GmbH | Bone anchoring device |
US8277494B2 (en) | 2007-07-20 | 2012-10-02 | Biedermann Technologies Gmbh & Co. Kg | Bone anchoring device |
WO2019013916A1 (en) * | 2017-07-10 | 2019-01-17 | American Sterilizer Company | Brake screw for surgical lighting systems |
US10473172B2 (en) | 2017-07-10 | 2019-11-12 | American Sterilizer Company | Brake screw for surgical lighting systems |
US10758280B2 (en) | 2017-10-09 | 2020-09-01 | Acumed Llc | System and method for bone fixation using a nail locked to an encircling anchor |
JP2020536687A (en) * | 2017-10-09 | 2020-12-17 | アキュームド・エルエルシー | Systems and methods for bone fixation using nails locked to all-around fastening anchors |
US11723699B2 (en) | 2017-10-09 | 2023-08-15 | Acumed Llc | System and method for bone fixation using a nail locked to an encircling anchor |
Also Published As
Publication number | Publication date |
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AU1290895A (en) | 1995-06-06 |
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