Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-08-06
2001-12-11
Recla, Henry J. (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S075000, C081S057370, C081S434000
Reexamination Certificate
active
06328746
ABSTRACT:
BACKGROUND OF THE INVENTION
Wire mesh and bone plates as methods of bone fixation have been extensively developed during the past few years. Replacement of damaged bone using metal implants is quite common and the current method of fixation has not changed for a considerable period.
Bone plates have been commonly used to replace fractured and unusable bone, particularly in neurosurgery. These preformed plates can be slightly modified by the surgeon to meet the requirements of a specific patient but, in general, are not alterable. In many instances, over a period of time, the bone grows under the plate; however, the plate remains implanted in the patient. The preformed bone plate is fixed to healthy bone by means of a number of small screws. These are small surgical screws that fit in the plate and hold it against the bone.
Wire mesh was developed to overcome some of the restrictions of bone plates. In many instances, preformed bone plates are impractical and the time necessary for the manufacture of the plate in the required form is prohibitive. Mesh was developed to allow the surgeon to form a plate that conforms to the required bone structure directly in the operating room. Mesh has undergone considerable development in design and materials. However, it is still basically an open structure with a number of fixation holes that can be cut and shaped as required. Most mesh is work-hardened, thus, once formed, it retains the required shape. Like bone plates, wire mesh is fixed to the bone by means of a number of small screws.
The current use of wire mesh for fixation of bone pieces in Reconstructive Surgery, Dentistry, Neurosurgery and Orthopedic Surgery has led to the development of multiple designs of mesh. These meshes are generally made out of a corrosion resistant material such as stainless steel or titanium, and have a multiplicity of holes for fixation to the bone by means of small surgical screws.
These surgical screws are usually small flat-head wood or sheet metal screws and are the primary means of attaching the plates or the mesh to the bone. The threads of the screws are designed for gripping the bone. The head of the screw can have any of a multiplicity of designs ranging from a straight slot, cruciate (Phillips head), hexagonal, or other such design. Due to the nature of the material used for implants, neither the screwdriver nor the screws can be of a magnetic material.
The screws are made of a material electrostatically compatible with the mesh, fit into the holes on the plate or mesh, and hold the plate or mesh against the bone. The plate or mesh is countersunk such that if the screw is attached correctly it will not protrude from the surface of the mesh. For correct contact, the screw, must, of course, be centered and perpendicular to the mesh and/or the plate. This imposes significant strain on the surgeon since he must not only keep track of these small components but must also place them absolutely straight; otherwise, the surface of the implant will not be smooth.
Current practice is to supply the mesh or bone plate in a tray with a multiplicity of screws of different sizes, to be used as required. These screws are generally not self-tapping. The surgeon selects the plate or forms the mesh according to the patient's requirements and then selects the appropriate screws for fixing the implant to the bone. He then drills the appropriate number of holes in the bone and uses a screwdriver to drive the screws into place. However, these screws used for mesh fixation are generally small, in the range of approximately one (1) to four (4) mm in length with a diameter ranging from one (1) to two (2) mm. As such, the screws are very difficult to handle even in a controlled environment. In the operating room, with its critical environment and conditions, requiring tracking of all instruments and quick efficient action, these extremely small screws create difficulties for the surgeon and staff. This creates undue stress on the surgeon who must not only place these extremely small screws into place, but must also not over-torque them during the installation, must maintain accurate alignment with the pre-drilled holes, and, above all, must not lose them in the wound. Since these screws are non-magnetic, if they “fall” into the wound they must be located and removed. If the screws are over-torqued during placement, they can shear, which adds an additional problem of removal of the sheared component from the bone and replacement.
The purpose of the present invention is to facilitate the handling, tracking and installation of these surgical screws onto the wire mesh in the operating room.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a self tapping screw that eliminates the need for pre-drilling a bone and aligning the plate in surgical procedures using wire mesh.
It is a further object of the invention to provide a means for manipulating and identifying the surgical screws, in particular, the surgical screws used for installing wire mesh and/or bone plate.
It is a further object of the invention to provide a means for tracking surgical screws, in particular, the surgical screws used in the installation of wire mesh and/or bone plate.
It is a further object of the invention to provide a means for attaching a surgical screw to a surgical screw driver such that they will remain joined until the screw is properly installed.
It is a further object of the invention to provide a means of installing surgical screws with a predefined torque.
It is a further object of the invention to provide a universal system for installation of screws that can be used on most current plates and meshes.
In accordance with the invention, a novel surgical screw, screw cartridge, surgical screw holder or magazine, and surgical screwdriver are provided herein. These components can be used independently of each other, giving the surgeon the flexibility required to deal with unique situations should they arise. However, in the preferred embodiment, they are designed to be used together as an integrated system. When used together, the components will provide an optimum method of installing a wire mesh and/or bone plate.
In accordance with one aspect of the invention, a self-tapping screw of particular design is provided herein.
In accordance with another aspect of the present invention, a surgical screw cartridge is provided herein. In the preferred embodiment, the screw cartridge is a disposable component. The cartridge facilitates manipulation of a surgical screw by a surgeon. The cartridge is preferably sized to be large enough for the surgeon to handle with gloved hands.
The cartridge provides a means for holding a surgical screw both manually and on a surgical screwdriver. This cartridge is designed to hold the screw onto the screwdriver until the screw is installed on though the wire mesh and/or bone plate into the bone, at which point the cartridge will automatically be discarded.
In a preferred embodiment, the cartridge can further be used to provide color coding of the surgical screws so that each screw size will be identified by the color of the cartridge, eliminating the possibility of mistaken screw selection. Also, the cartridge will provide a means of tracking lot numbers, and specifications of the screws.
The cartridge further provides a means for easily aligning the surgical screw with the wire mesh and/or bone plate, assuring that the screw will go in perpendicular to the surface of the mesh, providing a smooth surface, i.e., the screw flush to the wire mesh.
It is further preferred that the cartridge be constructed of a semi-rigid plastic material that will fall away of its own accord once the screw is accurately placed in the appropriate hole on the wire mesh and/or bone plate. This cartridge will be designed to work as a component of a magazine (described hereafter) or as a stand-alone item.
In accordance with a further aspect of the invention, a screw magazine is also provided herein. The screw magazine is preferably a disposable component as well.
Lewis William W
Recla Henry J.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
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