BONE PLATE SYSTEMS USING PROVISIONAL FIXATION
Bone plates with an upper surface, a bone contacting surface, and a plurality of holes extending through the upper and bone contact surfaces for receiving bone screws are disclosed. Each hole interchangeably accepts a compression screw for compression of a fracture and a locking screw that threads into the bone plate. Provisional fixation of a bone plate to a bone may be accomplished using provisional fixation pins through the screw-receiving holes of the bone plate.
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This application is a continuation of U.S. patent application Ser. No. 11/644,303, filed Dec. 22, 2006, now allowed, which is a continuation of U.S. patent application Ser. No. 10/952,047, filed Sep. 28, 2004, now abandoned, which is a continuation-in-part application of U.S. patent application Ser. No. 10/673,833, filed Sep. 29, 2003, now U.S. Pat. No. 7,179,260. The entire contents of the prior applications are hereby incorporated by reference.
FIELD OF THE INVENTIONThe invention relates generally to apparatuses for fixation of parts of a fractured bone, and, more particularly, to bone plates and bone plate assemblies for stabilization and compression of parts of a fractured bone and provisional fixation using holes in bone plates.
BACKGROUND OF THE INVENTIONBone fractures lead to complex tissue injuries involving both the bone and the surrounding soft tissue. Treated in a conservative way, fractures often result in malalignment or non-unions and may also lead to stiffness of adjacent joints. To reduce the occurrence of these problems, open reduction and internal fixation of the bone can be carried out. Anatomical reduction and stable internal fixation with plates and screws are very successful in treating bone fractures.
Good bone healing can also result from relative stability, where the clinical outcome is often dependent on obtaining correct length, axis, and rotation of the fractured bone rather than on precise anatomical reduction and absolute stability. To achieve this, while at the same time minimizing the amount of additional soft tissue trauma, treatment of multi-fragmented metaphyseal and diaphyseal fractures with plates and screws was developed.
An existing solution is plate and screw systems where the screws are locked in the plate. The plate and screws form one stable system and the stability of the fracture is dependent upon the stiffness of the construct. No compression of the plate onto the bone is required, which reduces the risk of primary loss of reduction and preserves bone blood supply. Locking the screw into the plate to ensure angular, as well as axial, stability eliminates the possibility for the screw to toggle, slide, or be dislodged and thereby strongly reduces the risk of postoperative loss of reduction. As the relationship between the locking screws and the plate is fixed, locking screws provide a high resistance to shear or torsional forces, but locking screws have a limited capability to compress bone fragments.
Furthermore, existing plates with openings that accept locking screws typically only accept certain screw sizes with specified types of screw heads. For example, an existing plate and screw system includes a lag screw with a shallow thread form and a conical screw head. This limits the angulation of the screw, and the thread form is not optimal for lagging bone pieces together. This may be limiting in certain cases, for example with a distal femur fracture where a surgeon desires to lag the condyles. Because such existing plates do not accept large screws with spherical screw heads, surgeons are limited to lagging fragments outside the plate or using screws which are poorly designed for this application.
Because of these shortcomings, many surgeons began expressing the desire to have plate and screw systems (or bone plate assemblies) where the surgeon can choose intraoperatively whether to use the bone plate with compression screws (also referred to as cortical or cancellous screws), locking screws, or with a combination of both. This led to the development of a combination slot, a compression slot combined with a partially threaded opening, that could receive either a compression screw or a locking screw.
Bone plate assemblies that combine compression screws and locking screws are ideal in certain clinical situations. Bone plates with combination slots, including partially threaded openings, are well known to those skilled in the art. The partially threaded portions allow either locking or compression screws to be used. Because the slots are only partially threaded, the locking screws may not be able to maintain the fixed angular relationship between the screws and plate under physiological loads. Specifically, the locking screws within the plate are only partially captured and thus only partially surrounded by threads. Under high stress and loading conditions, the slot may distort and allow the fixed angular relationship between the locking screw and plate to change. This can result in loss of fixation or loss of established intraoperative plate orientation. Because of the slot geometry, translation of the plate with compression screws may be limited to a single direction, which may be disadvantageous in reduction and manipulation of fragments.
Additionally, bone plates that allow for a surgeon to use provisional fixation techniques are also desirable. Provisional fixation of a bone plate to the bone allows the surgeon to fix the plate to the bone without the use of clamps or similar tools. In this way, the surgeon may place the bone plate in the proper position before inserting all of the locking screws into the bone plate and bone, while at the same time keeping excess instruments, such as clamps, out of the field of view of the surgeon and allowing for higher quality x-rays of the bone and bone plate construct during surgery.
Accordingly, there is a need for improved bone plates that may be used with both compression and locking screws for improved stabilization and compression of parts of a fractured bone. There is also a need for improved bone plates with holes that may be used for locking a bone plate to the bone, but that also accept different size screws with varying types of screw heads. Finally, there is need for improved bone plates that accept provisional fixation pins through the holes of the plate.
SUMMARY OF THE INVENTIONThe present invention provides bone plates and bone plate assemblies for stabilization and compression of parts of a fractured bone. According to an exemplary embodiment of the present invention, a bone plate includes an upper surface, a bone contacting surface, and at least one hole extending through the upper surface and the bone contacting surface that may interchangeably receive a locking screw and a compression screw, wherein each hole includes a thread that makes a complete revolution around the hole.
According to an exemplary embodiment, a bone plate comprises an upper surface, a bone contacting surface, and a plurality of holes for receiving bone screws, wherein each hole extends through the upper surface and the bone contacting surface, may interchangeably receive a locking screw and a compression screw, and includes a thread that makes a complete revolution around the hole. Each hole may further include a top portion extending from the upper surface and a bottom threaded portion extending from the top portion to the bone contacting surface. The bottom portion may be tapered with an included angle of less than about thirty degrees. The threads of each hole may be configured to receive threads of a head of a locking screw. Each hole may be configured to threadably engage a head of a locking screw and fix the locking screw with respect to the bone plate. Each hole may be configured to engage a head of a compression screw and provide compression of fractured bone fragments.
An exemplary embodiment of a method of reducing a bone fracture comprises inserting a provisional fixation pin through a first hole in a bone plate to couple the bone plate to the bone, wherein the first hole is one of a plurality of holes in the bone plate for receiving bone screws, drilling a hole in the bone through a second hole of the plurality of holes, and inserting a locking screw through the second hole and into engagement with the bone to fix the position of the bone plate. One or more additional provisional fixation pins may be inserted through one or more additional holes of the plurality of holes before or after drilling a hole in the bone. Each hole of the plurality of holes in the bone plate may interchangeably receive a locking screw and a compression screw and includes a thread that makes a complete revolution around the hole.
Another exemplary embodiment of a method of reducing a fracture of a bone comprises inserting a provisional fixation pin through a first hole in a bone plate to couple the bone plate to the bone, wherein the first hole is one of a plurality of holes in the bone plate for receiving bone screws, drilling a hole in the bone through a second hole of the plurality of holes, and inserting a compression screw through the second hole and into engagement with the bone to lag a bone fragment to the bone plate. Another hole may be drilled in the bone through a third hole of the plurality of holes and a locking screw inserted through the third hole and into engagement with the bone to fix the position of the bone plate. One or more additional provisional fixation pins may be inserted through one or more additional holes of the plurality of holes before or after drilling a hole in the bone. Each hole of the plurality of holes in the bone plate may interchangeably receive a locking screw and a compression screw and includes a thread that makes a complete revolution around the hole.
An exemplary embodiment of a bone plate assembly comprises a bone plate, at least one locking screw, at least one compression screw, and at least one provisional fixation pin. The bone plate includes an upper surface, a bone contacting surface, and a plurality of holes for receiving bone screws, wherein each hole extends through the upper surface and the bone contacting surface, may interchangeably receive a locking screw and a compression screw, and includes a thread that makes a complete revolution around the hole. The at least one provisional fixation pin may be received within at least one of the plurality of holes for receiving bone screws. The bone plate assembly may also include other provisional fixation pins that are to be used in pinholes that may be present in the bone plate, such that the bone plate assembly includes provisional fixation pins for use with both pinholes and other provisional fixation pins separately for use with holes for receiving bone screws.
Other exemplary embodiments of this invention include bone plates, bone plate assemblies, and methods of fracture reduction and provisional fixation further described herein and in co-pending U.S. application Ser. No. 10/673,833, which is incorporated herein by reference.
The present invention provides bone plates and bone plate assemblies for stabilization and compression of parts of a fractured bone. According to certain exemplary embodiments of this invention, a bone plate includes an upper surface, a bone contacting surface, and at least one hole extending through the upper surface and the bone contacting surface that may interchangeably receive a locking screw and a compression screw. The bone plate may include additional openings that receive only compression screws or only locking screws. The bone plate may also include pinholes that accept provisional fixation pins, but that are not large enough to receive bone screws.
A threaded head of an exemplary locking screw for use in accordance with this invention is received by threads in a corresponding hole such that the threads of the hole completely surround the threads of the head of the locking screw. This relationship between the head of the locking screw and the threads of the hole contributes to maintaining fixation of the bone plate and strengthening the plate and screw combination. As noted, a compression screw may also be received within the hole of the bone plate. As the compression screw is fully inserted within a bone, the head of the compression screw comes into contact with and rides along a top portion of the hole, allowing for fine adjustment of the position of the bone plate in more than one direction.
The particular bone plate 50 shown in these drawings includes a hole 52 extending through an upper surface 54 and a bone contacting surface 56 of bone plate 50.
A bottom portion 60 of hole 52 extends from the end of top portion 58 through bone contacting surface 56 of bone plate 50. Bottom portion 60 includes threads 62, as shown in
In the exemplary embodiment shown in
Locking screw 80 also includes an internal hex head 86, as shown in
Bone plate 90 includes a hole 92 extending through an upper surface 94 and a bone contacting surface 96 of bone plate 90. Hole 92 includes a top portion 98 extending downward from upper surface 94. As shown in
A bottom portion 100 of hole 92 extends from the end of top portion 98 through bone contacting surface 96 of bone plate 90. Bottom portion 100 includes threads 102. Some of threads 102 may extend into top portion 98 depending on the particular embodiment, but top portion 98 generally has only the beginning of thread leads, if any threading. Bottom portion 100 is not tapered, but rather is generally cylindrical in shape. In certain embodiments, for example, bottom portion 60 of hole 52 of bone plate 50, bottom portion 100 may be tapered at an included angle of less than about thirty degrees.
Certain exemplary embodiments of bone plates according to this invention include holes, such as hole 52 or hole 92, that not only receive compression or locking screws interchangeably but also accept multiple types of compression screw heads with varying outer and inner diameters and thread forms. A compression screw can be placed through such holes and use for fixation, provided the minor diameter of the screw shank does not exceed the minor diameter of the hole. The diameter of the head of the compression screw should not be less than the minor diameter of the hole because the compression screw would not then rest on any part of the bone plate as is necessary for fracture reduction.
Shown in some of the exemplary bone plates in
Preferably, certain embodiments of bone plates according to this invention include an upper surface, a bone contacting surface, and a plurality of holes extending through the upper surface and the bone contacting surface. Each hole may interchangeably receive locking and compression screw and includes a thread that makes a complete revolution around the hole (exemplary embodiments of such holes are hole 52 and hole 92 described above), and no other non-threaded holes or openings for receiving bone screws are present in the plates. Certain embodiments may also include non-threaded pinholes that are not capable of receiving bone screws, but which may be used for provisional fixation with provisional fixation pins.
Several exemplary embodiments of such bone plates are shown in FIGS. 27 and 29-33. For example,
An exemplary embodiment of a method of fracture reduction utilizing provisional fixation pins through a screw-receiving hole of a bone plate is described below. Numerous other exemplary embodiments of methods of fracture reduction using compression screws and/or locking screws, as well as, optionally, provisional fixation pins, are further described in co-pending U.S. application Ser. No. 10/673,833, which is incorporated herein by reference.
A fracture is reduced with convention forceps, and a bone plate of appropriate size and shape is placed over the fracture site. The bone plate is temporarily secured to the bone using provisional fixation pins. In a bone plate such as those shown in FIGS. 27 and 29-33 described above, provisional fixation pins may be used through either the pinholes or the screw-receiving holes of the bone plate. For example, a 2 mm diameter provisional fixation pin may be used through a pinhole, a 2.7 mm diameter provisional fixation pin may be used through a 3.5 mm screw-receiving hole, and a 3.5 mm diameter provisional fixation pin may be used through a 4.5 mm screw-receiving hole. In one embodiment, provisional fixation is accomplished through the screw-receiving holes only.
Once one or more provisional fixation pins are used through these holes to secure the bone plate to the bone temporarily, a hole is drilled in the bone through one of the other screw-receiving holes of the bone plate. A locking or compression screw with an appropriate head diameter is then inserted into the bone for fixation or for lagging bone fragments to the plate. Provisional fixation provides for temporarily securing the bone plate to the bone before placing fixation screws through the bone plate, so that one can be certain the bone plate is properly positioned before placing bone screws for permanent fixation of the bone plate to the bone. Moreover, with provisional fixation, x-rays can be taken of the bone plate/construct without excess instruments in the field of view.
The foregoing description of exemplary embodiments of the invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above disclosure. The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to make and utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope.
Claims
1. A bone plate system for reducing a fracture of a bone, the system comprising:
- a bone plate comprising an upper surface, a lower surface, and a hole extending between the upper and lower surfaces;
- a hole comprising a frustoconical portion, an upper opening at the upper surface, and a lower opening at the lower surface, the lower opening having a first diameter;
- a provisional fixation pin configured to be inserted within the hole for provisional engagement with the bone; and
- a fastener comprising a head and a bone engagement portion, the head comprising a spherical portion and the bone engagement portion having a second diameter less than the first diameter;
- wherein the spherical portion of the head engages the frustoconical portion of the hole when the fastener is inserted into the hole and the bone engagement portion engages the bone.
Type: Application
Filed: Mar 18, 2011
Publication Date: Nov 17, 2011
Applicant: SMITH & NEPHEW, INC. (Memphis, TN)
Inventors: Darin Gerlach (Cordova, TN), Anthony James (Bartlett, TN)
Application Number: 13/051,715
International Classification: A61B 17/80 (20060101);