WO2013098828A1 - A screw blocking mechanism for a bone plate - Google Patents

A screw blocking mechanism for a bone plate Download PDF

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Publication number
WO2013098828A1
WO2013098828A1 PCT/IN2011/000905 IN2011000905W WO2013098828A1 WO 2013098828 A1 WO2013098828 A1 WO 2013098828A1 IN 2011000905 W IN2011000905 W IN 2011000905W WO 2013098828 A1 WO2013098828 A1 WO 2013098828A1
Authority
WO
WIPO (PCT)
Prior art keywords
rivet
bone plate
screw
pin
bone
Prior art date
Application number
PCT/IN2011/000905
Other languages
French (fr)
Inventor
Patrick J. KLUGER
Original Assignee
GEORGE, Samuel W.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by GEORGE, Samuel W. filed Critical GEORGE, Samuel W.
Priority to PCT/IN2011/000905 priority Critical patent/WO2013098828A1/en
Publication of WO2013098828A1 publication Critical patent/WO2013098828A1/en

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical 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
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/80Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates
    • A61B17/8033Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates having indirect contact with screw heads, or having contact with screw heads maintained with the aid of additional components, e.g. nuts, wedges or head covers
    • A61B17/8042Cortical plates, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates having indirect contact with screw heads, or having contact with screw heads maintained with the aid of additional components, e.g. nuts, wedges or head covers the additional component being a cover over the screw head
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/56Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58Surgical 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
    • A61B17/68Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/70Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
    • A61B17/7059Cortical plates

Abstract

A bone plate with a screw blocking mechanism and a method of blocking screw from backout of a bone plate are disclosed. The bone plate comprises at least one screw hole having a periphery, the screw hole adapted to receive a bone screw, at least one rivet hole having a periphery, adapted to receive a rivet along with a rivet pin, wherein the rivet hole is positioned in such a way that the rivet at least partially overlaps a portion of at least one bone screw in order to prevent the bone screw from backout.

Description

A SCREW BLOCKING MECHANISM FOR A BONE PLATE

FIELD OF INVENTION

The present invention generally relates to a bone plate having a screw blocking mechanism. In particular, the present invention relates to an anterior cervical bone plate having a screw blocking mechanism to prevent the screw from backout and a method for blocking screw from backout in an anterior cervical bone plate.

BACKGROUND OF INVENTION

Bone plates and bone screws are often used in orthopaedic applications. For instance, bone plates and bone screws are used in stabilization or fusion of vertebral bodies in the spine and are also used in fracture fixation. In many instances there is a concern that bone screws may loosen after implantation of bone plate. To the extent that this occurs, it has been desirable to ensure that the screw does not fully remove itself from the bone and bone plate. Metal-metal constructs in orthopaedic surgery are usually assembled by means of screw connections. This type of assembly requires at least one of the parts to be connected having sufficient thickness to provide leverage for the screw's thread and the connecting screw's head to protrude. Moreover, the assembly is time consuming. Further, if not secured, threaded screws can spontaneously undo themselves and disintegration of constructs is sometimes observed.

In spine surgery, stabilisations of the cervical spine are often done by fixing a metal plate from anterior with bone screws to the vertebral bodies to be united. The discs between the vertebral bodies are removed and the resulting gaps are filled with bone. The bone consolidates with the neighbouring vertebral bodies, leading to sound bony fusion within approximately 6 months. During the process of bone consolidation, some resorption typically takes place between the graft and the contacting vertebral bodies, leading to a small degree of collapse. This collapse happens mainly in the posterior part of the region of fusion by subsidence opposite to the stabilising plate, which has been fixed to the vertebral bodies from anterior.

This small collapse in the process of bone consolidation can easily be accepted, because it enhances the physiological lordosis of the cervical spine. The collapse described goes along with micro-movements between the stabilising plate and their anchoring bone screws, and between the bone screws and the bone, which represents a small amount of loosening of the bone screws. With every movement of the patient's neck, and with every swallowing act, the patient's oesophagus and other soft tissues glide up and down over the surface of the stabilising plate. Therefore a progressive, spontaneous, undoing of the bone screws fixing the plate is occasionally observed even after full consolidation of the bone fusion. Such a protruding screw can perforate the oesophagus, or it can come out completely and migrate through the patient's organism, with serious hazards possible. To prevent the bone screws coming out, a number of different designs have been introduced. There are mechanisms to lock the screws to the plate, but they tend to also prevent the micro- movements described above, which allow fast consolidation in desirable position. In other devices, the screws have improved bone leverage by an expansion mechanism, but these screws are significantly more expensive and their removal can become difficult.

Most plate-screw designs offering a protection against screw loosening show a small lid covering the bone screw's heads partially or completely. This lid can consist of a spring or different other mechanism, frequently it is a small screw with a large head, with the inherent disadvantages mentioned above. Thus there arises a need for an anterior cervical bone plate having a screw blocking mechanism to prevent the screw from backout and a method for blocking screw from backout in an anterior cervical bone plate. OBJECT OF INVENTION

An object of the present invention is to provide an anterior cervical bone plate having a screw blocking mechanism to prevent the screw from backout. Another object of the present invention is to provide a method for blocking screw from backout in an anterior cervical bone plate.

SUMMARY OF INVENTION

According to one aspect of the present invention, which achieves the objectives, relates to a bone plate with a screw blocking mechanism, the bone plate comprises at least one screw hole having a periphery, the screw hole adapted to receive a bone screw. At least one rivet hole having a periphery, adapted to receive a rivet along with a rivet pin, wherein the rivet hole is positioned in such a way that the rivet at least partially overlaps a portion of at least one bone screw in order to prevent the bone screw from backout.

According to another aspect of the present invention, which achieves the objectives, relates to a method of blocking screw from backout of a bone plate the method comprising the steps of, inserting a rivet on a rivet pin such that sleeve of the rivet slides on the rivet pin till it reaches tapered portion of rivet pin; placing the rivet along with the rivet pin on rivet hole of the bone plate such that the rivet and the rivet pin are intact in the rivet hole; pulling the rivet pin form hallow inner surface of the rivet such that the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw; cutting and removing the unwanted portion of the rivet pin once the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates a bone plate with a screw blocking mechanism, in accordance with an exemplary embodiment of the present invention; Fig. 2 illustrates a rivet being slide on a rivet pin to reach the tapered portion of the rivet pin, in accordance with an exemplary embodiment of the present invention; Fig. 3 illustrates a bone plate with a rivet at least partially overlapping on at least one bone screw as viewed from top of the bone plate, in accordance with an exemplary embodiment of the present invention; Fig. 4 illustrates a bone plate with a rivet at least partially overlapping on at least one bone screw as viewed from bottom of the bone plate, in accordance with an exemplary embodiment of the present invention; and

Fig. 5 illustrates a flowchart depicting a method for blocking screw from backout of a bone plate, in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to Fig, 1 , a bone plate with a screw blocking mechanism is illustrated, in accordance with an exemplary embodiment of the present invention. An anterior cervical bone plate having a screw blocking mechanism to prevent the screw from backout is provided with a bone plate (1) which has four screw holes (2) each having a periphery and each screw hole is adapted to receive a bone screw (3). The bone plate also has two rivet holes (4) each having a periphery and each rivet hole is adapted to receive a rivet (5) along with a rivet pin (6). Each bone screw when screwed in the bone plate moves in the axis perpendicular to the bone plate. The rivet hole is positioned on the bone plate in such a way that the rivet at least partially overlaps a portion of at least one bone screw in order to prevent the bone screw from backout. The rivet has hallow inner surface with a broad head in one end to overlap on the bone screw and with a narrow sleeve on the other end to slide and to rest on the rivet pin. The rivet pin is a cylindrical rod with a pointed conical shape in one end and with an outward tapered portion in the other end such that the diameter of the outward tapered portion is greater than the diameter of the cylindrical portion. The hallow inner surface of the rivet slides on the rivet pin. The diameter of the tapered portion of the rivet pin is made larger than the diameter of the hallow inner surface of the rivet, such that the rivet slides on the rivet pin until the sleeve of the rivet reaches the tapered portion of the rivet pin. Once the rivet along with the rivet pin is placed intact on the rivet hole, then the rivet pin is pulled out by means of a rivet gun through the inner surface of the rivet such that the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw. Once the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw, the unwanted portion of the rivet pin is cut and removed. The rivet is made up of deformable metal and the rivet pin is made up of harder alloy.

According to present invention, the protection against a bone screw backing out from the bone plate is provided by a rivet with a large flat head. The rivet is inserted into rivet hole after inserting the bone screws. From its position the rivet's head partially covers the screw heads, thus preventing the screws from backing out.

In the present invention, the rivets consist of a sleeve and a head made from a soft, easy deformable metal like an aluminium or copper alloy, and of a rivet pin of a harder alloy, usually steel. With a riveting gun, the rivet pin is pulled through the rivet's sleeve, by which the rivet pin's head deforms the sleeve, until it is ripped off the rivet pin.

It is learnt that the mechanical principle of riveting can also be realised by only using materials established in orthopaedic implant technology, e.g. pure titanium and titanium alloy. This was achieved by altering dimensions like wall thickness of the sleeves and diameter of the rivet pin and by modifying the design of the rivet pin resulting in reliably functioning rivets. Different surface finishing of the parts can also improve the functioning. The rivets can be operated with a specifically designed riveting gun, which can be sterilised for use in surgery. Similar arrangement can predictably lead to rivets made from other alloys used for orthopaedic implants, like artificial joints. There rivets can beneficially be used for instance to fix muscle groups or tendons to the joint prosthesis. In addition, cores and sleeves of the rivets to functioning from orthopaedic alloys by modifying dimensions, by hardening treatments, by surface treatments, and by micro-design can be engineered.

Referring to Fig. 2, the rivet being slide on a rivet pin to reach the tapered portion of the rivet pin is illustrated, in accordance with an exemplary embodiment of the present invention. The rivet has hallow inner surface with a broad head in one end to overlap on the bone screw and with a narrow sleeve on the other end to slide and to rest on the rivet pin.

Referring to Fig. 3 and Fig. 4, the bone plate with a rivet at least partially overlapping on at least one bone screw as viewed from top and bottom of the bone plate respectively is illustrated, in accordance with an exemplary embodiment of the present invention. Once the rivet along with the rivet pin is placed intact on the rivet hole, then the rivet pin is pulled out by means of a rivet gun through the inner surface of the rivet such that the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw. Once the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw, the unwanted portion of the rivet pin is cut and removed

Referring to Fig. 5, a flowchart depicting a method for blocking screw from backout of a bone plate is illustrated, in accordance with another embodiment of the present invention. A method for blocking screw from backout in an anterior cervical bone plate is provided by inserting a rivet on a rivet pin such that sleeve of the rivet slides on the rivet pin till it reaches tapered portion of rivet pin (501); placing the rivet along with the rivet pin on rivet hole of the bone plate such that the rivet and the rivet pin are intact in the rivet hole (502); pulling the rivet pin form hallow inner surface of the rivet such that the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw (503); and cutting and removing the unwanted portion of the rivet pin once the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw (504).

Claims

WE CLAIM:
1. A bone plate with a screw blocking mechanism, the bone plate comprising:
at least one screw hole having a periphery, the screw hole adapted to receive a bone screw; and
at least one rivet hole having a periphery, adapted to receive a rivet along with a rivet pin, wherein the rivet hole is positioned in such a way that the rivet at least partially overlaps a portion of at least one bone screw in order to prevent the bone screw from backout.
2. The bone plate as claimed in claim 1 , wherein the rivet has hallow inner surface with a broad head in one end to overlap on the bone screw and with a narrow sleeve on the other end to slide and to rest on the rivet pin.
3. The bone plate as claimed in claim 1 , wherein the rjvet pin is a cylindrical rod with a pointed conical shape in one end and with an outward tapered portion in the other end such that the diameter of the outward tapered portion is greater than the diameter of the cylindrical portion.
4. The bone plate as claimed in claims 2 and 3, wherein hallow inner surface of the rivet slides on the rivet pin.
5. The bone plate as claimed in claims 2 to 4, wherein the diameter of the tapered portion of the rivet pin is made larger than the diameter of the hallow inner surface of the rivet, such that the rivet slides on the rivet pin until the sleeve of the rivet reaches the tapered portion of the rivet pin.
6. The bone plate as claimed in any one of the preceding claims, wherein once the rivet along with the rivet pin is placed intact on the rivet hole, then the rivet pin is pulled out through the inner surface of the rivet such that the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw.
7. The bone plate as claimed in claim 6, wherein once the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw, the unwanted portion of the rivet pin is cut and removed.
8. The bone plate as claimed in claim 1 , wherein, the bone screw when screwed in moves in the axis perpendicular to the bone plate.
9. The bone plate as claimed in any one of the preceding claims wherein, the rivet is made up of deformable metal and the rivet pin is made up of harder alloy.
10. A method of blocking screw from backout of a bone plate the method comprising the steps of:
inserting a rivet on a rivet pin such that sleeve of the rivet slides on the rivet pin till it reaches tapered portion of rivet pin;
placing the rivet along with the rivet pin on rivet hole of the bone plate such that the rivet and the rivet pin are intact in the rivet hole;
pulling the rivet pin form hallow inner surface of the rivet such that the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw; and
cutting and removing the unwanted portion of the rivet pin once the rivet is secured with the bone plate and the rivet at least partially overlaps on at least one bone screw.
PCT/IN2011/000905 2011-12-29 2011-12-29 A screw blocking mechanism for a bone plate WO2013098828A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IN2011/000905 WO2013098828A1 (en) 2011-12-29 2011-12-29 A screw blocking mechanism for a bone plate

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IN2011/000905 WO2013098828A1 (en) 2011-12-29 2011-12-29 A screw blocking mechanism for a bone plate

Publications (1)

Publication Number Publication Date
WO2013098828A1 true WO2013098828A1 (en) 2013-07-04

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ID=45926847

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IN2011/000905 WO2013098828A1 (en) 2011-12-29 2011-12-29 A screw blocking mechanism for a bone plate

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WO (1) WO2013098828A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998034556A1 (en) * 1997-02-11 1998-08-13 Michelson Gary K Skeletal plating system
US20040127900A1 (en) * 2002-12-31 2004-07-01 Konieczynski David D. Resilient bone plate and screw system allowing bi-directional assembly
US20100292737A1 (en) * 2009-05-15 2010-11-18 Sean Suh Orthopedic Plate Blocking Assembly

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998034556A1 (en) * 1997-02-11 1998-08-13 Michelson Gary K Skeletal plating system
US20040127900A1 (en) * 2002-12-31 2004-07-01 Konieczynski David D. Resilient bone plate and screw system allowing bi-directional assembly
US20100292737A1 (en) * 2009-05-15 2010-11-18 Sean Suh Orthopedic Plate Blocking Assembly

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

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