Patent Description:
Bone fractures and other bone damage are regularly treated by fusion. Bones are currently fused with the assistance of implants, such as, plates and screws which are designed to hold the bones or bone pieces in place while healing occurs and the bones or bone pieces are fused together. Improved devices and methods for fusing bones together are needed.

<CIT> discloses a bone screw for treating a bone fracture having a detent assembly on a body portion thereof.

<CIT> discloses devices and methods for anchoring implants to bone.

The invention relates to a bone fixation device as claimed hereafter.

Advancement of the state of bone fusion and bone fixation devices and implants and the surgical management relating to the clinical presentation of damaged or fractured bones within the body is believed desirable. Several embodiments of the bone fixation devices or bone fusion devices used to treat patients suffering from either diseased or damaged bones includes a first member, a second member, at least three spring members, and a ring member.

The present invention provides, a bone fixation device including a first member, a second member shaped to engage the first member, and at least one deformable member positioned between the first member and the second member.

The present invention provides further , a bone fixation device including a female member with a proximal end and a distal end, a male member with a proximal end and a distal end, and at least one elastic element positioned between the female member and the male member.

Further, additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention.

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. Associated methods are also described herein to aid understanding of the invention, but these do not form part of the claimed invention. The foregoing and other objects, features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings, in which <FIG>, <FIG> illustrate embodiments of the invention and in which:.

Generally stated, disclosed herein is a bone fixation device that may include a first member, a second member, at least one spring member, and a ring member. As used herein, the terms "bone fixation device," "bone fusion device," "medical device," "device," and "implant" may be used interchangeable as they essentially describe the same device. Further, the corresponding insertion tool may also be referred to as "tool" or "instrument" and these terms may be used interchangeably. Further, described herein is a method of assembling the bone fixation device. Finally, described herein is a method of using the bone fixation device to compress two pieces of bone.

In this detailed description and the following claims, the words proximal, distal, anterior, posterior, medial, lateral, superior and inferior are defined by their standard usage for indicating a particular part of a bone or implant according to the relative disposition of the natural bone or directional terms of reference. For example, "proximal" means the portion of an implant farthest from the insertion end, while "distal" indicates the portion of the implant nearest the insertion end. As for directional terms, "anterior" is a direction towards the front side of the body, "posterior" means a direction towards the back side of the body, "medial" means towards the midline of the body, "lateral" is a direction towards the sides or away from the midline of the body, "superior" means a direction above and "inferior" means a direction below another object or structure.

As depicted in <FIG> and <FIG>, a bone fixation device or bone fusion device <NUM> includes a first member <NUM> and a second member <NUM>. The bone fixation device <NUM> may also include at least one spring member <NUM> and a ring member <NUM>. The second member <NUM> may be sized and shaped to fit into the first member <NUM> with, for example, the at least one spring member <NUM> and the ring member <NUM> positioned between the first member <NUM> and second member <NUM>. The at least one spring member <NUM> may also be positioned, for example, inside an opening <NUM> of the second member <NUM>. The first member <NUM> may be positioned, for example, at a proximal end <NUM> of the bone fixation device <NUM>, while the second member <NUM> may be positioned, for example, at a distal end <NUM> of the bone fixation device <NUM>. The bone fixation device <NUM> may be, for example, a screw, intramedullary rod, spinal rod, bone plate, and the like for joining together, compressing or pressing together at least two bones or pieces of bone or alternatively for expanding or distracting at least two bones or pieces of bone. Intramedullary rods may be used, for example, during the compression or expansion across long bone fractures, as described in greater detail below with reference to <FIG>. The spinal rods may be used, for example, during the compression or distraction of a segment of the spinal column for stabilization of a spine, as described in greater detail below with reference to <FIG>. In addition, bone plates may be used, for example, during the compression or expansion across bone fractures or spinal fusions, such as, cervical plating, as described in greater detail below with reference to <FIG>.

The first member <NUM>, also shown in <FIG>, may be, for example, a female member. The first member <NUM> may include a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The terms "first end" and "proximal end" may be used interchangeably herein and the terms "second end" and "distal end" may be used interchangeably herein as they essentially refer to the same ends. The first member <NUM> may have an opening <NUM> extending from the first end <NUM> to the second end <NUM> along the longitudinal axis of the first member <NUM>. The opening <NUM> may form an interior surface <NUM>. The opening <NUM> of the first member <NUM> may also include a groove <NUM> positioned near the second end <NUM>. The terms "groove," "slot" or "member groove" may be used interchangeably herein as they essentially refer to the same indentation. The groove <NUM> may be cut into the wall of the first member <NUM> and extend from the opening <NUM> into the first member <NUM> toward the exterior surface <NUM> of the first member <NUM>. The interior surface <NUM> may be, for example, a relatively hexagonal or polygonal shape from the first end <NUM> to the groove <NUM>. The opening <NUM> may also include at least one channel or slot <NUM> inset into the interior surface <NUM> and extending from the first end <NUM> toward the second end <NUM> and stopping when the channels <NUM> extend into the groove <NUM>. The at least one channel <NUM> may receive the at least one spring member <NUM>. The bone fixation device <NUM> may include, for example, at least three channels <NUM> and at least three spring members <NUM>, as shown in <FIG>, <FIG>, <FIG>. The at least three channels <NUM> may be positioned radially around the opening <NUM> to provide circumferential forces to facilitate equal compressive loads. For example, where the interior surface <NUM> is relatively hexagonally shaped, the channels <NUM> may be positioned on every other portion of the interior surface <NUM>, for example, on the first, third, and fifth surfaces and the second, fourth, and sixth surfaces may be generally planar. The shape of the interior surface may also be, for example, relatively octagonal or another polygonal shape with an even number of sides.

With continued reference to <FIG>, <FIG>, and <FIG>, the exterior surface <NUM> of the first member <NUM> may be, for example, generally cylindrical. The exterior surface <NUM> may include a threaded portion or threaded end <NUM> and a protrusion or extension <NUM>. The protrusion <NUM> may extend away from the exterior surface <NUM> near the first end <NUM> to form an engagement portion for coupling to an insertion tool or resorbable member for insertion into a patient. The protrusion <NUM> may be configured, for example, as a tapered surface that extends down to the exterior surface <NUM> to form rounded edges on the protrusion <NUM>. The threaded portion <NUM> may be positioned, for example, toward the middle of the bone fixation device <NUM> between the protrusion <NUM> and the second end <NUM> of the first member <NUM>. The threaded portion <NUM> may extend only along a portion of the exterior surface <NUM> from the protrusion <NUM> to the second end <NUM> or alternatively, the threaded portion <NUM> may extend from the protrusion <NUM> to the second end <NUM> of the first member <NUM>.

As shown in <FIG> and <FIG> and with continued reference to <FIG> and <FIG>, the second member <NUM> may have a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The terms "first end" and "proximal end" may be used interchangeably herein and the terms "second end" and "distal end" may also be used interchangeably herein as the generally refer to the same end. The second member <NUM> may be, for example, a male member. The second member <NUM> may include a cannulation or channel <NUM> extending from the first end <NUM> to the second end <NUM> through the generally central portion of the second member <NUM> along the longitudinal axis of the second member <NUM>. The cannulation <NUM> may be sized to receive a guide wire, guide pin, or the like to facilitate placement in vivo. It is also contemplated that the channel <NUM> may receive, for example, the at least one spring member <NUM>. The second member <NUM> may also have an exterior surface <NUM>. The exterior surface <NUM> of the second member <NUM> may include a threaded region or threaded end <NUM> positioned near the second end <NUM> and a shaft region <NUM> extending from the threaded region <NUM> to the first end <NUM>. The threaded region <NUM> of the second member <NUM> may have, for example, a smaller diameter than the threaded portion <NUM> of the first member <NUM>. Alternatively, the threaded region <NUM> of the second member <NUM> may have the same diameter as the threaded portion <NUM> of the first member. In addition, the threaded ends <NUM>, <NUM> may have, for example, the same threads or different threads. The threads may be selected based on the type and condition of the bone they are being inserted into to ensure the threaded ends <NUM>, <NUM> grip onto the bones or bone pieces while translation of the bones is occurring.

As shown in <FIG>, the shaft region <NUM> may include, for example, a first portion <NUM> with a generally cylindrical shape and a second portion <NUM> with a relatively hexagonal or polygonal shape. The second portion <NUM> may extend from the first end <NUM> of the second member <NUM> toward the threaded region <NUM> and the first portion <NUM> may be positioned between the threaded region <NUM> and the second portion <NUM>. The second portion <NUM> may also include at least one depression or groove <NUM> near the first end <NUM> of the second member <NUM>. The at least one depression <NUM> may include, for example, three depressions positioned radially around the exterior surface of the shaft region <NUM>. Where the second portion <NUM> of the shaft region <NUM> has, for example, a polygonal shape with an even number of sides, such as, a hexagon, octagon, or the like, the depressions <NUM> may be positioned on every other side of the polygonal shape. As shown in <FIG>, the second portion <NUM> is generally hexagonal shaped and the depressions <NUM> are positioned on every other side of the exterior surface <NUM> to enable insertion of the ring member <NUM>. The second portion <NUM> may also include at least one channel or slot <NUM> extending from the at least one depression <NUM> toward the first portion <NUM>. The at least one channel <NUM> may be inset into the exterior surface <NUM>. The at least one channel <NUM> may receive the at least one spring member <NUM>.

The bone fixation device <NUM> may include, for example, any number of channels <NUM> and any number of spring members <NUM>, such as one to twelve channels <NUM> and one to twelve spring members <NUM>. In one embodiment, as shown in <FIG> and <FIG>, the bone fixation device <NUM> may include, for example, at least three channels <NUM> and at least three spring members <NUM>. The at least three channels <NUM> may also be positioned radially around the second portion <NUM> of the exterior surface <NUM>. The exterior surface <NUM> of the second portion <NUM> of the shaft region <NUM> may have a shape corresponding to the shape of the opening <NUM> in the first member <NUM>. For example, where the exterior surface <NUM> of the second portion <NUM> of the shaft region <NUM> has a relatively hexagonally shape, the channels <NUM> may be positioned on every other portion of the exterior surface <NUM>, for example, on the first, third, and fifth surfaces and the second, fourth, and sixth surfaces may be generally planar. The shape of the exterior surface may also be, for example, relatively octagonal or another polygonal shape with any number of sides. The exterior surface may have any shape with an even or odd number of sides and a spring channel may be located in one or more of the sides of the exterior surface. At least one spring <NUM> will be positioned in the at least one spring channel <NUM>.

The at least one spring member <NUM> may be, for example, three spring members <NUM> as shown in <FIG>, <FIG>, and <FIG>. The terms "at least one spring member," "at least one deformable member," and "at least one elastic element" may be used interchangeably herein as the essentially refer to the same members. The bone fixation device <NUM> may have, for example, at least three spring members <NUM> that are positioned between at least three channels <NUM> of the first member <NUM> and at least three channels <NUM> of the second member <NUM> when the second member <NUM> is inserted into the first member <NUM>. The at least three spring members <NUM> may be, for example, three single springs or three sets of at least two springs. It is also contemplated that any number of springs or elastic elements, such as solid elastic polymers, nitinol members, or the like, may be used to make up the at least one spring member <NUM> based on the desired compressive properties of the spring members. The spring members <NUM> may be, for example, spiral spring members, straight spring members, or any deformable members to allow for the compression and/or distraction of the deformable member and then the transition of the deformable member back to a relaxed state. In one embodiment, the deformable member <NUM> may be a straight spring with a tab at a first end and a tab at a second end for engaging the first and second members <NUM>, <NUM> of the bone fixation device <NUM> and a deformable member extending between the first and second tabs. The straight spring may be made of, for example, a deformable material, such as, nitinol. It is also contemplated that one spring member <NUM> may be used and the one spring member <NUM> may be positioned within the opening <NUM> of the second member <NUM>.

Referring now to <FIG>, the ring member <NUM> is shown. The terms "ring member," "member," "ring," "locking member," and "fastener" may be used interchangeably herein as they refer to the same structure. The member <NUM> may include a body <NUM>. The body <NUM> may have, for example, a generally cylindrical or C shape and may include an open portion to enable the member <NUM> to be inserted onto the shaft region <NUM> of the second member <NUM>. The member <NUM> may also include at least one protrusion or tab <NUM> extending out from an interior surface of the body <NUM>. The at least one protrusion <NUM> may be sized and shaped to correspond to the size and shape of the at least one channel <NUM> of the second member <NUM>. In the depicted embodiment of <FIG>, the member <NUM> includes, for example, three protrusions <NUM>. It is also contemplated that the member <NUM> may be replaced with, for example, a crimp, set screws, or the like which couples the first member <NUM> to the second member <NUM> and provides a base for engagement with the at least one spring member <NUM>.

Further, although not shown, one spring member <NUM> may be used and positioned in channel <NUM>, the ring member <NUM> will be configured to engage the spring member <NUM> inside the channel <NUM>. For example, the ring member <NUM> may be positioned on the exterior surface <NUM> of the second member <NUM> and extend transversely through at least a portion of the channel <NUM> to provide a base for the spring member <NUM> to exert force on during compression and expansion. The ring member <NUM> may extend through an opening, for example, at least one of channels <NUM> may be open to the channel <NUM>. The ring member <NUM> may extend transversely through the entire channel <NUM> and out the side opposite where it entered the exterior surface <NUM> of the shaft region <NUM> or only partially through the channel <NUM>. The ring member <NUM> will extend transversely through the channel <NUM> far enough to provide a base for the entire or a sufficient portion of the spring to engage during compression and expansion to move the first and second members <NUM>, <NUM> relative to each other.

The bone fixation device <NUM> may also include a locking mechanism (not shown) to prevent the first member <NUM> and second member <NUM> from lengthening after compression of the bone fixation device <NUM> is completed. The locking mechanism (not shown) may be, for example, a ratchet mechanism or an alternative mechanism which allows the bone fixation device <NUM> to lengthen when engaged with the insertion tool or resorbable member and then to shorten after removal of the insertion tool or break down of the resorbable member, but prevents the bone fixation device <NUM> from lengthening again after removal of the insertion tool (not shown) or break down of the resorbable member (not shown). After the bone fixation device <NUM> shortens, the locking mechanism may, for example, engage the first member <NUM> and second member <NUM> to prevent the bone fixation device <NUM> from lengthening again when external forces are applied on the bones or bone pieces after insertion of the device <NUM> into the patient.

By way of specific example, the bone fixation device <NUM> may be a screw. The screw <NUM> may be a <NUM> screw for example, with the opening <NUM> of the first member <NUM> having, for example, a width at the first end <NUM> of approximately <NUM> to <NUM> and a diameter at the second end <NUM> of approximately <NUM> to <NUM> and the shaft region <NUM> of the second member <NUM> having, for example, an outer diameter of approximately <NUM> to <NUM>.

In an alternative embodiment of the bone fixation device <NUM>, the ring member <NUM> may be removed and at least a portion of the end of the second end <NUM> of the first member <NUM> may be crimped or folded over to engage the at least one channel <NUM> and at least one spring member <NUM>. The second end <NUM> may be, for example, crimped or folded over at the positions corresponding to or aligning with the position of the channels <NUM> and spring members <NUM> or alternatively, around the entire circumference of the first member <NUM>.

A method of assembling a bone fixation device <NUM> is shown in <FIG>. The method may include, for example, obtaining a first member, a second member, a ring member, and at least one spring member <NUM>. The method may also include, for example, sliding the ring member onto the second member <NUM> and inserting a portion of the second member into the first member <NUM>. Further, the method may include, for example, positioning the at least one spring member between the first member and the second member <NUM> and sliding the second member into the first member to engage the ring member <NUM>.

The method of assembling a bone fixation device <NUM> is described in greater detail below with reference to <FIG>, <FIG>, and <FIG>. The method includes obtaining the first member <NUM>, a second member <NUM>, a ring member <NUM>, and at least one spring member <NUM>. The at least one spring member <NUM> may be, for example, three spring members <NUM> as shown in <FIG>. Next the ring member <NUM> may be inserted onto the shaft region <NUM> of the second member <NUM>, as shown in <FIG> and <FIG>. The ring member <NUM> may be inserted by aligning, for example, two end protrusions of the at least one protrusion <NUM> with the depressions <NUM> on shaft region <NUM>. Then, the ring member <NUM> may be slid to align with the at least one protrusion <NUM> with the at least one channel <NUM> of the second member <NUM>. Once the at least one protrusion <NUM> of the member <NUM> is aligned with the at least one channel <NUM>, the member <NUM> may be translated from the first end <NUM> distally toward the second end <NUM> of the second member <NUM> until the at least one protrusion <NUM> reaches the bottom of the at least one channel <NUM>. Next, the tip of the first end <NUM> of the second member <NUM> may be inserted into the opening <NUM> of the first member <NUM>. The first and second members <NUM>, <NUM> may overlap by, for example, overlapping the first member <NUM> over the first end <NUM> of the second member <NUM> down to approximately the depressions <NUM>. Then, the at least one spring member <NUM> may be positioned in the at least one channel <NUM> of the second member <NUM>. It is also contemplated that the at least one spring member <NUM> may be positioned within the at least one channel <NUM> of the second member <NUM>. The first member <NUM> may then be slid over the second member <NUM>, as shown in <FIG> and <FIG>. Once the at least one spring member <NUM> is positioned within the at least one channel <NUM>, the second member <NUM> may be fully inserted into the first member <NUM> until the ring member <NUM> engages the groove <NUM> in the opening <NUM> of the first member <NUM>, as shown in <FIG> and <FIG>.

Referring now to <FIG>, a method for using the bone fixation device <NUM> is illustrated. The method may include, for example, obtaining a bone fixation device <NUM> and an insertion tool <NUM>. The method may also include, for example, inserting a portion of the first member into the insertion tool <NUM> and moving the second member as the insertion tool engages the first member <NUM>. Finally, the method may further include inserting the bone fixation device into at least one bone <NUM> and removing the insertion tool from the bone fixation device <NUM>.

The method for using the bone fixation device <NUM> is described in greater detail below with reference to <FIG>. The bone fixation device <NUM> may be inserted into a patient by first optionally inserting a guide wire (not shown) into the position where bone correction is desired. The proper position may be confirmed using imaging, for example, x-ray to ensure the guide wire is properly positioned. The length of the bone fixation device <NUM> may be confirmed or determined. The bone fixation device <NUM>, such as shown in <FIG>, may then be obtained. In addition, an insertion tool (not shown) may be obtained and moved to engage the bone fixation device <NUM>.

The bone fixation device <NUM> is engaged by positioning the insertion tool (not shown) over the protrusion <NUM> on the first end <NUM> of the first member <NUM>. An exterior portion of the insertion tool surrounds the protrusion <NUM> of the first member <NUM> for insertion into a patient. As the insertion tool engages the first member <NUM> at the proximal end <NUM> of the bone fixation device <NUM>, the insertion tool also includes an interior contacting member that extends out from the center of the exterior portion of the insertion tool and engages the first end <NUM> of the second member <NUM>. The interior contacting member of the insertion tool engages the first end <NUM> to translate the second end <NUM> of the second member <NUM> away from the first end <NUM> of the first member <NUM>. As the second member <NUM> is moved away, the ring member <NUM> which is coupled to the first member <NUM> slides along the at least one channel <NUM> of the second member <NUM>. The ring member <NUM> slides from a position near the first portion <NUM> of the shaft <NUM> towards the first end <NUM> of the second member <NUM>. As the ring member <NUM> slides towards the first end <NUM>, the protrusions <NUM> of the member <NUM> contact the end of the at least one spring member <NUM>. The at least one spring member <NUM> is then compressed between the at least one protrusion <NUM> of the ring member <NUM> and the first end of the at least one channel <NUM> of the first member <NUM> and the top of the depressions <NUM> of the second member <NUM> as the ring member <NUM> moves towards the first end <NUM> of the second member <NUM>. As the ring member <NUM> moves along the at least one channel <NUM> and compresses the at least one spring member <NUM>, the threaded ends <NUM> and <NUM> move in opposite directions thereby lengthening the bone fixation device <NUM>, as shown in <FIG> and <FIG>, to an uncompressed position. Since the ring member <NUM> is coupled to the first member <NUM> and the insertion tool is coupled to the first member <NUM>, the second member <NUM> is able to translate away from the first member <NUM> as the insertion tool engages the second member <NUM>. Once the at least one spring member <NUM> is fully compressed the at least one spring member <NUM> acts as an extension stop by preventing the device <NUM> from extending any further.

Next, the distal end <NUM> of the bone fixation device <NUM> is inserted into the patient over the guide wire. The position of the bone fixation device <NUM> may then be checked to confirm proper positioning and length.

The insertion tool (not shown) may then be removed from the first member <NUM>. As the insertion tool is removed, active compression is initiated on the bones or bone pieces that the bone fixation device <NUM> is engaged to and the bone fixation device <NUM> begins to move back to the shortened compressed position, as shown in <FIG>. The active compression results from the at least one spring member <NUM> extending back to its uncompressed position and exerting a force on the ring member <NUM>. As the force is exerted on the ring member <NUM> by the at least one spring member <NUM>, the ring member <NUM> translates toward the second end <NUM> of the second member <NUM> along the at least one channel <NUM>. Since the ring member <NUM> is coupled to the groove <NUM> in the first member <NUM>, the ring member <NUM> will translate towards the second end <NUM> of the second member <NUM> resulting in the first member <NUM> being pulled toward the distal end <NUM> of the bone fixation device <NUM> and causing the bones or bone portions engaged by the first member <NUM> and second member <NUM> to be compressed together.

The bone fixation device <NUM> shortens as the at least one spring member <NUM> expands back to a resting position. The at least one spring member <NUM> may allow the bone fixation device <NUM> to shorten, for example, more than approximately ten percent of the length of the bone fixation device <NUM>. The bone fixation device <NUM> may, for example, allow for high forces, such as approximately <NUM> lbs to <NUM> lbs, to be applied over the distance of approximately <NUM>. In addition, the bone fixation device may allow for compression forces to be the strongest at full extension and then decrease as the bone fixation device <NUM> shortens. Thereby, providing an initially high load compression to enhance healing of the bones or bone pieces and then as healing of the bones or bone pieces occurs, the compression load decreases.

An alternative use for the bone fixation device <NUM>, i.e. lengthening of bones, is described below. It is also contemplated that an alternative tool may be used to shorten the bone fixation device <NUM> before insertion into a patient to allow for lengthening of the bones after insertion. For example, the insertion tool (not shown) would engage the protrusion <NUM> on the first end <NUM> of the first member <NUM> and also engage the first end <NUM> of the second member <NUM>. The tool will pull the first end <NUM> of the second member <NUM> proximally to shorten the device <NUM>. As the tool engages the device <NUM> and pulls the first end <NUM> of the second member <NUM> proximally, the proximal edge of the first portion <NUM> of the second member <NUM> engages the ring member <NUM> and slides the ring member <NUM> along the at least one channel <NUM> toward the first end <NUM> of the first member <NUM>. As the ring member <NUM> slides along the at least one channel <NUM>, the ring member <NUM> engages the at least one spring member <NUM> and compresses the at least one spring member <NUM> between the at least one protrusion <NUM> of the ring member <NUM> and the first end of the at least one channel <NUM> of the first member <NUM> and the top of the depressions <NUM> of the second member <NUM>. Once the device <NUM> is shortened to the desired length, it may be inserted into a patient. The device <NUM> may also optionally be inserted over a guide wire.

Next, the insertion tool may be removed from the bone fixation device <NUM>. Once the tool is removed, the at least one spring member <NUM> may exert a force on the ring member <NUM> which will in turn exert a force on the edge of the first portion <NUM> of the second member <NUM> to move the second member <NUM> away from the first member <NUM> of the bone fixation device <NUM>. As the at least one spring member <NUM> returns to its' resting, uncompressed state, the bone fixation device <NUM> lengthens. As the bone fixation device <NUM> lengthens and moves the first member <NUM> and second member <NUM> away from each other, the bones or bone segments that are coupled to the first member <NUM> and second member <NUM> are separated. The bone fixation device <NUM> may be used to provide a distraction force across a joint, fracture site, or osteotomy site.

Alternatively, if a resorbable member (not shown) is used, after placement of the bone fixation device <NUM> the patient's incision may be closed. If a resorbable member is used, the insertion tool would not need to include a lengthening or shortening mechanism. The resorbable member will hold the bone fixation device <NUM> in the desired extended or shortened position until the resorbable member starts to break down. As the resorbable member breaks down or erodes over time from exposure to the in vivo environment inside of the patient, the at least one deformable member <NUM> may be released and exert force on the members <NUM>, <NUM> to lengthen or shorten the device <NUM>, as described in greater detail above. The resorbable member may be, for example, a cross pin, pawl, or the like which locks the device <NUM> in the desired extended or shortened position until the resorbable member erodes.

Where the bone fixation device <NUM> is used to facilitate bone distraction, the bone fixation device <NUM> may also include a locking mechanism (not shown). The locking mechanism allows for the second member <NUM> to be pulled proximally toward the first member <NUM>. The second member <NUM> will then move away from the first member <NUM> once the insertion tool is removed or resorbable member breaks down from the bone fixation device <NUM>. In addition, once the insertion tool is removed or resorbable member breaks down and the second member <NUM> begins translating away, the locking mechanism will prevent the second member <NUM> from again translating towards the first member <NUM>. The locking mechanism may be, for example, a ratcheting mechanism that engages the first member <NUM> and second member <NUM> to prevent the shortening of the bone fixation device <NUM> when the device <NUM> is implanted and the insertion tool removed or resorbable member breaks down.

<FIG> and <FIG>depict another embodiment of a bone fixation device or bone fusion device <NUM>. The bone fixation device <NUM> may be, for example, an intramedullary rod for insertion into a medullary cavity of a bone. The device <NUM> may include a first member <NUM>, a second member <NUM>, at least one spring member <NUM>, and a ring member <NUM>. The second member <NUM> may be dimensioned to fit into the first member <NUM> and the at least one spring member <NUM> and the ring member <NUM> may be, for example, positioned between the first member <NUM> and second member <NUM>.

The first member <NUM>, as shown in <FIG> and <FIG>, may include a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The first member <NUM> may also have an opening <NUM> extending from the first end <NUM> to the second end <NUM> along the longitudinal axis of the first member <NUM>. The opening <NUM> may form an interior surface <NUM> which includes a groove <NUM> positioned near the second end <NUM> of the first member <NUM>. The groove <NUM> may extend into the first member <NUM> from an interior surface <NUM> toward the exterior surface <NUM> of the first member <NUM>. The interior surface <NUM> of the first member <NUM> may have, for example, a relatively hexagonal, octagonal, or other polygonal shape from the first end <NUM> to the groove <NUM>. In addition, the opening <NUM> may include at least one channel or slot <NUM> inset into the interior surface <NUM> and extending from the first end <NUM> toward the second end <NUM> and terminating when the channels <NUM> extend into the groove <NUM>. The first member <NUM> may be, for example, a female member. The device <NUM> may include, for example, at least three channels <NUM> which may receive at least three spring members <NUM>, as shown in <FIG>. The at least three channels <NUM> may be positioned radially around the opening <NUM> as described in greater detail above with reference to channels <NUM> and opening <NUM>, which will not be described again here for brevity sake.

With continued reference to <FIG> and <FIG>, the exterior surface <NUM> of the first member <NUM> may be, for example, generally cylindrical. The exterior surface <NUM> may include at least one through hole <NUM> for fixing the rod <NUM> to a first portion of a patient's bone. In the depicted embodiment, the at least one through hole <NUM> may be, for example, two through holes <NUM>. Alternative numbers of holes <NUM> are also contemplated to secure the rod <NUM> to a patient's bone and the number of holes <NUM> may correlate to the length of the bone being fused.

The second member <NUM>, as shown in <FIG>, may have a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The second member <NUM> may include a cannulation or channel <NUM> extending from the first end <NUM> to the second end <NUM> along the longitudinal axis of the second member <NUM> and through the generally central portion of the second member <NUM>. The cannulation <NUM> may be sized to receive a guide wire, guide pin, or the like to facilitate placement in vivo. The second member <NUM> may also include at least one through hole <NUM> near the second end <NUM> for fixing the rod <NUM> to a second portion of a patient's bone. In the depicted embodiment, the at least one through hole <NUM> may be, for example, two through holes <NUM>.

As shown in <FIG>, the second member <NUM> may also have an exterior surface <NUM> with a coupling portion <NUM> positioned near the first end <NUM> for connecting the second member <NUM> to the first member <NUM>. The exterior surface <NUM> positioned distal to the coupling portion <NUM> may have a generally cylindrical shape, while the coupling portion <NUM> may have a relatively polygonal shape. The coupling portion <NUM> may also include at least one depression or groove <NUM> near the first end <NUM> of the second member <NUM>. The at least one depression <NUM> may be, for example, three depressions <NUM> positioned radially around the exterior surface <NUM> of the coupling portion <NUM>. For example, if the coupling portion <NUM> has a polygonal shape with an even number of sides, the depressions <NUM> may be positioned on every other side of the polygonal shape. The at least one depression <NUM> is positioned around the coupling portion <NUM> so that the ring member <NUM> may be inserted onto the second member <NUM>. The coupling portion <NUM> may also include at least one channel or slot <NUM> extending from the at least one depression <NUM> toward the second end <NUM>. The at least one channel <NUM> may be inset into the exterior surface <NUM> and may be sized to receive the at least one spring member <NUM>. The bone fixation device <NUM> may include, for example, any number of channels <NUM> and any number of spring members <NUM>, which may be one to twelve channels <NUM> and one to twelve spring members <NUM>. In one embodiment, the channels <NUM> and spring members <NUM> may be, for example, three channels <NUM> and at least three spring members <NUM>, as shown in <FIG> and <FIG>. The channels <NUM> may be positioned radially around the coupling portion <NUM>. It is also contemplated that in an alternative embodiment, the channel <NUM> may receive, for example, the at least one spring member <NUM>. The coupling portion <NUM> may be sized to fit within the opening <NUM> of the first member <NUM>. In addition, the shape of the coupling portion <NUM> may correspond to the shape of the opening <NUM> in the first member <NUM>. The second member <NUM> may be, for example, a male member.

The at least one spring member <NUM> may be positioned between the at least one channel <NUM> of the first member <NUM> and the at least one channel <NUM> of the second member <NUM> when the second member <NUM> is inserted into the first member <NUM>. The at least one spring member <NUM> is as described above with reference to <FIG>, <FIG>, and <FIG>, which will not be described again here for brevity sake.

As shown in <FIG>, <FIG>, and <FIG>, the ring member <NUM> may be of the type described above with reference to <FIG>, which will not be described again here for brevity sake. The ring member <NUM> may be inserted by sliding the at least one protrusion <NUM> into the at least one depression <NUM> of the second member <NUM> until the at least one protrusion <NUM> aligns with the at least one channel <NUM>. Once at least one protrusion <NUM> is aligned with the at least one channel <NUM>, the ring member <NUM> may be translated toward the distal end of the at least one channel <NUM>. After the ring member <NUM> is positioned at the distal end of the at least one channel <NUM>, the at least one spring <NUM> may be inserted into the channel <NUM> and the coupling portion <NUM> may be inserted into the opening <NUM> in the first member <NUM>. When the coupling portion <NUM> is inserted into the opening <NUM>, the at least one spring <NUM> slides into the at least one channel <NUM> of the first member <NUM>. Alternatively, it is contemplated that one spring member <NUM> may be used and positioned in channel <NUM>. If the spring member <NUM> is positioned in the channel <NUM>, the ring member <NUM> will be configured to engage the spring member <NUM> inside the channel <NUM>. The alternative embodiment is described in greater detail above with respect to bone fixation device <NUM> and will not be described again here for brevity. The coupling portion <NUM> may be inserted into the first member <NUM> until the ring member <NUM> engages the groove <NUM> in the first member <NUM> to secure the first member <NUM> and the second member <NUM> together.

The bone fixation device <NUM> may also include a locking mechanism (not shown) to prevent the first member <NUM> and the second member <NUM> from lengthening after compression is complete or from shortening after distraction is completed. The locking mechanism may be of the type described above in greater detail with respect to device <NUM> and which will not be described again here for brevity sake.

By way of specific example, the bone fixation device <NUM> is an intramedullary rod. The intramedullary rod may be, for example, approximately <NUM> to <NUM> with a first member <NUM> with a diameter of, for example, approximately <NUM> to <NUM> and a second member <NUM> with a diameter of, for example, approximately <NUM> to <NUM>.

The method of assembling a bone fixation device as shown in <FIG> and described in greater detail above may also be used to assemble the bone fixation device <NUM>.

The bone fixation device <NUM> may be inserted into a patient using the method of <FIG>. The method is described in greater detail with respect to device <NUM> and may include, for example, obtaining an assembled bone fixation device <NUM> and insertion tool (not shown). The method may also include, for example, inserting a portion of the first member <NUM> into the insertion tool (not shown) and moving the second member <NUM> as the insertion tool engages the first member <NUM> to, for example, lengthen the device <NUM> if compression of the bone is desired. As the device <NUM> is lengthened the at least one spring member <NUM> will be compressed by the ring member <NUM>. The insertion tool may engage the device <NUM> in a manner similar to how the insertion tool engages the device <NUM> as described above in greater detail and which will not be described again here for brevity sake. Next, the method may include inserting the bone fixation device <NUM> into, for example, the medullary cavity of a long bone.

The device <NUM> may be inserted into the medullary cavity by first accessing the patient's bone by, for example, making an incision to reach the patient's bone. Then, a guide wire (not shown) may optionally be inserted into the position where bone correction is desired. The position of the guide wire may be checked using imaging, for example, an x-ray to ensure the guide wire is properly positioned. The guide wire may then be used to determine or confirm the length of the intramedullary rod <NUM> that is needed for insertion into the bone. A drill, reamer, or the like may then be inserted over the guide wire to create a larger opening in the bone to access the medullary cavity. Once the larger opening is formed, the drill or reamer may be removed and the bone fixation device <NUM> with the coupled insertion tool may be inserted into the medullary cavity through the larger opening. The device <NUM> may be inserted over the guide wire, or optionally, the guide wire may be removed prior to insertion of the device <NUM>. If necessary, the device <NUM> may be hammered into the medullary cavity across the fracture. Once the rod <NUM> reaches the desired position, at least one fastener (not shown), such as, a bone screw, locking bone screw, or the like, may be inserted into the through holes <NUM> to secure the first member <NUM> to a first portion of the bone. Next, at least one fastener (not shown), such as, a bone screw, locking bone screw, or the like, may be inserted into the through holes <NUM> to secure the second member <NUM> to a second portion of the bone.

Following the insertion of the fasteners to secure the first and second members <NUM>, <NUM> to the bone, the insertion tool may be removed from the first member <NUM> of the rod <NUM>. After the insertion tool is removed, the device <NUM> may exert active compression on the bones secured to the device <NUM>. As active compression occurs, the bone fixation device <NUM> begins to move back to a shortened compressed position, as shown in <FIG>. The active compression of the rod <NUM> results from the at least one spring member <NUM> extending back to its uncompressed position which in turn exerts a force on the ring member <NUM> to move it toward the distal end of the at least one channel <NUM>. As the ring member <NUM> translates down the channel <NUM>, the first member <NUM> is pulled toward the second end <NUM> of the second member <NUM> and the bones engaged by the first and second members <NUM>, <NUM> are compressed together. Finally, the incisions in the patient may be closed. The intramedullary rod <NUM> may, for example, create an active circumferential compression to the fracture site transferring the axial load to the bone and reducing the function of the rod <NUM> as a load bearing device. Thus, use of the rod <NUM> may enhance healing of the bone.

It is also contemplated that the bone fixation device <NUM> may alternatively be used for distraction of a fractured bone after the insertion, by shortening the device <NUM> prior to insertion into a patient, as described above in greater detail with regards to bone fixation device <NUM> and which will not be described again here for brevity sake.

Further, it is contemplated that a resorbable member (not shown) may be used instead of the insertion tool to shorten or lengthen the device <NUM> for insertion into the patient. Therefore, when a resorbable member is used, the insertion tool could be any driver or holder that could insert the device <NUM> into the patient. When a resorbable member is used, once the bone fixation device <NUM> is placed in the patient, the patient's incision may be closed. The resorbable member will hold the bone fixation device <NUM> in the desired extended or shortened position until the resorbable member starts to break down or erode. As the resorbable member breaks down over time from exposure to the in vivo environment inside of the patient, the at least one deformable member <NUM> may be released and exert force on the members <NUM>, <NUM> to lengthen or shorten the device <NUM>, as described in greater detail above. The resorbable member may be, for example, a cross pin, pawl, or the like which locks the device <NUM> in the desired extended or shortened position until the resorbable member erodes.

Another alternative embodiment fixation or fusion device <NUM> is shown in <FIG> and <FIG>. The fixation device <NUM> may be, for example, a spinal rod for use with, for example, a pedicle screw system or other spinal correction system which uses rods. The device <NUM> may include a first member <NUM>, a second member <NUM>, at least one spring member <NUM>, and a ring member <NUM>. The second member <NUM> may be sized to fit into at least a portion of the first member <NUM> and the at least one spring member <NUM> and ring member <NUM> may be, for example, positioned between the first member <NUM> and second member <NUM>. The at least one spring member <NUM> and ring member <NUM> may be of the types described in greater detail above with reference to device <NUM> and which will not be described again here in detail for brevity sake.

As shown in <FIG> and <FIG>, the first member <NUM> may include a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The first member <NUM> may also include a first coupling portion <NUM> and second portion <NUM>. The first coupling portion <NUM> and second portion <NUM> may be, for example, generally cylindrical and the first coupling portion <NUM> may have, for example, a diameter that is larger than or the same size as the second portion <NUM>. The second portion <NUM> may be, for example, a solid rod, while the first coupling portion <NUM> includes an opening <NUM>. The opening <NUM> may extend into the coupling portion <NUM> of the first member <NUM> from the second end <NUM>. The opening <NUM> may extend along a portion of the longitudinal axis of the first member <NUM> from the second end <NUM> toward the first end <NUM>. For example, the opening <NUM> may extend only within the coupling portion <NUM> of the first member <NUM>. The opening <NUM> may form an interior surface <NUM> within the first member <NUM>. The interior surface <NUM> may include a groove <NUM> positioned near the second end <NUM> of the first member <NUM>. The groove <NUM> may extend into the first member <NUM> from the interior surface <NUM> toward the exterior surface of the coupling portion <NUM> of the first member <NUM>. The interior surface <NUM> of the first member <NUM> may have, for example, a relatively hexagonal or other polygonal shape starting after the groove <NUM> and extending toward the first end <NUM>. The opening <NUM> may further include at least one channel or slot <NUM> inset into the interior surface <NUM> and extending from the groove <NUM> toward the first end <NUM> of the first member <NUM>.

The first member <NUM> may be, for example, a female member. The device <NUM> may include, for example, any number of channels <NUM> and any number of spring members <NUM>, such as one to twelve channels <NUM> and one to twelve spring members <NUM>. In one embodiment, the at least one channel <NUM> and the at least one spring member <NUM> may be, for example, at least three channels <NUM> which may receive at least three spring members <NUM>, as shown in <FIG>, <FIG> and <FIG>. The at least three channels <NUM> may be positioned radially around the opening <NUM> as described in greater detail above with reference to channels <NUM> and opening <NUM>, which will not be described again here for brevity sake.

The second member <NUM>, as shown in <FIG>, may have a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The second member <NUM> may also have a coupling portion <NUM> positioned near the first end <NUM> for connecting the second member <NUM> to the first member <NUM> and a second portion <NUM> extending from the coupling portion <NUM> to the second end <NUM>. The second portion <NUM> may have, for example, an exterior surface <NUM> with a generally cylindrical shape. The second portion <NUM> may have a diameter, for example, that is approximately the same as the diameter of the second portion <NUM>. The width of the coupling portion <NUM> may be, for example, slightly smaller than the diameter of the second portion <NUM>. The coupling portion <NUM>, however, may have a relatively polygonal shape and may also include at least one depression or groove <NUM> near the first end <NUM> of the second member <NUM>. The at least one depression <NUM> may be three depressions <NUM> positioned radially around the coupling portion <NUM>. For example, if the coupling portion <NUM> has a polygonal shape with an even number of sides, the depressions <NUM> may be positioned on every other side of the polygonal shape. The at least one depression <NUM> is positioned around the coupling portion <NUM> such that the ring member <NUM> may be inserted onto the second member <NUM>. The coupling portion <NUM> may also include at least one channel or slot <NUM> extending from the at least one depression <NUM> toward the second end <NUM> of the second member <NUM>. The at least one channel <NUM> may be inset into the surface of the coupling portion <NUM> and may be sized to receive the at least one spring member <NUM>. The fixation device <NUM> may also include, for example, any number of channels <NUM> and any number of spring members <NUM>, such as one to twelve channels <NUM> and one to twelve spring members <NUM>. In one embodiment, the at least one channel <NUM> and the at least one spring member <NUM> may be, for example, three channels <NUM> and at least three spring members <NUM>, as shown in <FIG> and <FIG>. The channels <NUM> may be positioned radially around the coupling portion <NUM>. It is also contemplated that in an alternative embodiment, the channel <NUM> may receive the at least one spring member <NUM>. The coupling portion <NUM> may be sized to fit within the opening <NUM> of the first member <NUM>. In addition, the shape of the coupling portion <NUM> may correspond to the shape of the opening <NUM> in the first member <NUM>. The second member <NUM> may be, for example, a male member.

The at least one spring member <NUM> may be positioned between the at least one channel <NUM> of the first member <NUM> and the at least one channel <NUM> of the second member <NUM> when the second member <NUM> is inserted into the first member <NUM>. The at least one spring member <NUM> is as described above with reference to <FIG>, <FIG> and <FIG>, which will not be described again here for brevity sake.

As shown in <FIG>, <FIG>, and <FIG>, the ring member <NUM> may be of the type described above with reference to <FIG>, which will not be described again here for brevity sake. The ring member <NUM> may be inserted by sliding the at least one protrusion <NUM> into the at least one depression <NUM> of the second member <NUM> until the at least one protrusion <NUM> aligns with the at least one channel <NUM>. Once at least one protrusion <NUM> is aligned with the at least one channel <NUM>, the ring member <NUM> may be translated toward the distal end of the at least one channel <NUM>. After the ring member <NUM> is positioned at the distal end of the at least one channel <NUM>, the at least one spring <NUM> may be inserted into the channel <NUM> and the coupling portion <NUM> may be inserted into the opening <NUM> in the first member <NUM>. When the coupling portion <NUM> is inserted into the opening <NUM>, the at least one spring <NUM> slides into the at least one channel <NUM> of the first member <NUM>. Alternatively, it is contemplated that one spring member <NUM> may be used and positioned in channel <NUM>. If the spring member <NUM> is positioned in the channel <NUM>, the ring member <NUM> will be configured to engage the spring member <NUM> inside the channel <NUM>. The alternative embodiment of the spring member <NUM> and ring member <NUM> configuration is described in greater detail above with respect to bone fixation device <NUM> and will not be described again here for brevity. The coupling portion <NUM> may be inserted into the first member <NUM> until the ring member <NUM> engages the groove <NUM> in the first member <NUM> to secure the first member <NUM> and the second member <NUM> together.

The fixation device <NUM> may also include a locking mechanism (not shown) to prevent the first member <NUM> and the second member <NUM> from lengthening after compression is complete or from shortening after distraction is completed. The locking mechanism may be of the type described above in greater detail with respect to device <NUM> and which will not be described again here for brevity sake.

By way of specific example, the fixation device <NUM> is a spinal rod. The spinal rod may be a <NUM> rod which may be compressed between, for example, approximately <NUM> and <NUM>, or distracted or lengthened, for example, approximately <NUM> and <NUM>.

The method of assembling a bone fixation device as shown in <FIG> and described in greater detail above may also be used to assemble the fixation device <NUM>.

The fixation device <NUM> may be used with a spinal stabilization system, for example, a pedicle screw system. The fixation device <NUM> may be, for example, spinal rods which may replace the rods currently used in spinal stabilization systems. In use a spinal stabilization procedure may be performed as currently done using pedicle screws. Once the pedicle screws are in place in the vertebra along the patient's spine, then the spinal rods <NUM> may be inserted into the pedicle screws in place of the currently used rods. The spinal rods <NUM> could be inserted with an insertion tool (not shown) which would hold the spinal rods <NUM> in the desired position, for example, either lengthened or shortened, while the first member <NUM> is secured to a first pedicle screw and a second member <NUM> is secured to a second pedicle screw.

Alternatively, the first member <NUM> of the spinal rods <NUM> could be secured to a first pedicle screw and then the second member <NUM> translated either proximally or distally to shorten or lengthen the rod <NUM>. The spinal rods <NUM> would be lengthened or uncompressed if compression of the vertebra was desired. Alternatively, the spinal rods <NUM> would be shortened or compressed if distraction or lengthening of the vertebra was desired. Once the desired position of the second member <NUM> is achieved, the second member <NUM> is secured to the second pedicle screw.

The spinal rods <NUM> may be secured to the pedicle screws using a fastener, for example, a set screw. Once the spinal rods <NUM> are secured to the pedicle screws, the insertion tool may be removed or the surgeon may release the spinal rod <NUM> to allow for compression or distraction of the vertebra attached to the pedicle screws. When the spinal rods <NUM> are released an axial load is applied across the segment of the spine to be fused and a traction force is experienced between the two vertebral bodies.

As the axial load is applied, the device <NUM> begins to move back to a shortened compressed position or to a lengthened uncompressed position. The axial load of the rod <NUM> results from the at least one spring member <NUM> extending back to its uncompressed position which in turn exerts a force on the ring member <NUM> to move the second member <NUM> relative to the first member <NUM>. As the spring member <NUM> expands to its uncompressed position, the first member <NUM> is either pushed or pulled with respect to the second end <NUM> of the second member <NUM> and the attached vertebra either distract or compress. Finally, the incisions in the patient may be closed.

It is contemplated that a resorbable member (not shown) may be used instead of the insertion tool to lengthen or shorten the device <NUM>. When a resorbable member is used, after the device <NUM> is placed in the patient with a standard driver and/or holder, the patient's incision may be closed. The resorbable member will hold the device <NUM> in the desired extended or shortened position until the resorbable member starts to break down or erode. As the resorbable member breaks down over time from exposure to the in vivo environment inside of the patient, the at least one deformable member <NUM> may be released and exert force on the members <NUM>, <NUM> to lengthen or shorten the device <NUM>, as described in greater detail above. The resorbable member may be, for example, a cross pin, pawl, or the like which secures the device <NUM> in the desired extended or shortened position until the resorbable member erodes.

Referring now to <FIG>, a plating device <NUM> with a first member <NUM>, a second member <NUM>, and at least one spring <NUM> is shown. The at least one spring <NUM> is as described above with reference to device <NUM>, which will not be described again here for brevity sake. The first member <NUM>, as shown in <FIG> and <FIG>, may include a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The first member <NUM> may also include an attachment portion <NUM> at the second end <NUM> and a coupling portion <NUM> at the first end <NUM>. The first member <NUM> may be, for example, generally T-shaped, although other shapes that provide a first portion for attachment to a bone or vertebra and a second portion for coupling to the second member <NUM> are also contemplated. The attachment portion <NUM> may be a plate section with at least one opening <NUM> for receiving a fastener, for example, a bone screw to secure the first member <NUM> to a bone or vertebra. In the depicted embodiment, the first member <NUM> includes two openings <NUM>, although alternative numbers of openings <NUM> are also contemplated based on the size of the first member <NUM> and the bone or vertebra which the first member <NUM> will be secured to. As shown in <FIG>, the coupling portion <NUM> may include a female coupling member <NUM> extending along a first side of the coupling portion <NUM> and a male coupling member <NUM> extending along a second side of the coupling portion <NUM> opposite the first side. The female coupling member <NUM> may include a channel <NUM> extending from the first end <NUM> to the attachment portion <NUM>. The coupling portion <NUM> may also include at least one groove <NUM> extending from a position near the first end <NUM> to a position near the attachment portion <NUM>. The at least one groove <NUM> may be sized to receive at least one spring member <NUM>. The coupling portion <NUM> may include, for example, three grooves <NUM> for receiving three springs <NUM>.

The second member <NUM>, as shown in <FIG> and <FIG>, may include a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The first member <NUM> may also include an attachment portion <NUM> at the first end <NUM> and a coupling portion <NUM> at the second end <NUM>. The second member <NUM> may be, for example, generally T-shaped, although other shapes that provide a first portion for attachment to a bone or vertebra and a second portion for coupling to the first member <NUM> are also contemplated. The attachment portion <NUM> may be a plate section with at least one opening <NUM> for receiving a fastener, for example, a bone screw to secure the second member <NUM> to a bone or vertebra. In the depicted embodiment, the second member <NUM> includes two openings <NUM>, although alternative numbers of openings <NUM> are also contemplated based on the size of the second member <NUM> and the bone or vertebra to which the second member <NUM> will be secured. The coupling portion <NUM> may include a female coupling member <NUM> extending along a first side of the coupling portion <NUM> and a male coupling member <NUM> extending along a second side of the coupling portion <NUM> opposite the first side. The female coupling member <NUM> may include a channel <NUM> extending from the second end <NUM> to the attachment portion <NUM>. The coupling portion <NUM> may also include at least one groove <NUM> extending from a position near the second end <NUM> to a position near the attachment portion <NUM>. The at least one groove <NUM> may be sized to receive at least one spring member <NUM>. The coupling portion <NUM> may include, for example, any number of grooves <NUM> and any number of springs <NUM>, such as, one to twelve grooves <NUM> for receiving one to twelve springs <NUM>. As shown in the depicted embodiments, the coupling portion <NUM> includes, for example, three grooves <NUM> for receiving three springs <NUM>.

The plating device <NUM> may also include a locking mechanism or securement mechanism which engages the first member <NUM> and second member <NUM> to prevent the members <NUM>, <NUM> for disengaging.

The plating device <NUM> may be assembled by aligning the female coupling member <NUM> of the coupling portion <NUM> with the male coupling member <NUM> of the coupling portion <NUM> and the male coupling member <NUM> of the coupling portion <NUM> with the female coupling member <NUM> of the coupling portion <NUM>. Once aligned the male coupling members <NUM>, <NUM> may be partially inserted into the female coupling members <NUM>, <NUM>, respectively. After the first member <NUM> is partially inserted into the second member <NUM>, the at least one spring <NUM> may be inserted between the at least one grooves <NUM>, <NUM>. The at least one spring <NUM> may need to be compressed to enable insertion between the at least one grooves <NUM>, <NUM>. Next, the at least one spring <NUM> will uncompress and the device <NUM> will be positioned in a resting position until the device is implanted into a patient.

The plating device <NUM> may be secures to bones or vertebra in a desired position to promote fusion of the bones or vertebra. The plating device <NUM> may be inserted into a patient by first making an incision and preparing the bone or vertebra site where fusion is needed. Next, the plating device <NUM> may be, for example, lengthened to compress the at least one spring <NUM>. The plating device <NUM> may be lengthened using an insertion tool or by the surgeon pulling the first and second members <NUM>, <NUM> apart. Once the plating device <NUM> is lengthened it may be inserted over the bones or vertebra where fusion is desired. The first member <NUM> may be secured to a first bone or vertebra by inserting at least one fastener, for example, a bone screw, through the at least one opening <NUM>. Then the second member <NUM> may be secured to a second bone or vertebra by inserting at least one fastener, for example, a bone screw, through the at least one opening <NUM>. After the first and second members <NUM>, <NUM> are secured to the first and second bones or vertebra, the plating device <NUM> may be released and the at least one spring <NUM> will return to its uncompressed position. As the at least one spring <NUM> returns to its uncompressed position, the spring <NUM> exerts a force on the first and second members <NUM>, <NUM> in the grooves <NUM>, <NUM> near the attachment portions <NUM>, <NUM> and the plating device <NUM> shortens. The force applied to the first and second members <NUM>, <NUM> by the spring <NUM> will apply axial loading across the bone or spinal segment being fused.

Alternatively, the plating device <NUM> may be inserted into the patient in a shortened position. When the shortened device <NUM> is released after being secured to the patient's bones or vertebra, the at least one spring <NUM> will return to its uncompressed position by exerting a force on the first and second members <NUM>, <NUM> to push them apart and lengthen the device <NUM>.

The insertion tool may be replaced by a resorbable member (not shown) to secure the device <NUM> in a desired extended or shortened position during insertion. When a resorbable member is used, after the plating device <NUM> is placed in the patient with, for example, a standard driver and/or holder, the patient's incision may be closed. The resorbable member will hold the plating device <NUM> in the desired extended or shortened position until the resorbable member starts to break down or erode. As the resorbable member breaks down over time from exposure to the in vivo environment inside of the patient, the at least one deformable member <NUM> may be released and exert force on the members <NUM>, <NUM> to lengthen or shorten the device <NUM>, as described in greater detail above. The resorbable member may be, for example, a cross pin, pawl, or the like which secures the device <NUM> in the desired extended or shortened position until the resorbable member erodes.

Referring now to <FIG>, another bone fixation device <NUM> is shown. The bone fixation device <NUM> includes a first member <NUM>, a second member <NUM>, and at least one spring or deformable member <NUM>. The terms "spring member," "deformable member" and "elastic element" may be used interchangeably herein as they essentially refer to the same members. The bone fixation device <NUM> may also include at least one locking member <NUM>. The second member <NUM> may be sized and shaped to fit into the first member <NUM> with, for example, at least one spring member <NUM> and the at least one locking member <NUM> positioned between the first member <NUM> and the second member <NUM>. The bone fixation device <NUM> may be, for example, a screw, intramedullary rod, spinal rod, bone plate, and the like for joining together, compressing or pressing together at least two bones or pieces of bone or alternatively for expanding or distracting at least two bones or pieces of bone, as described in greater detail above and which will not be described again here for brevity sake.

The first member <NUM>, as shown in <FIG>, may be, for example a female member. The first member <NUM> may include a first end <NUM> and a second end <NUM> opposite the first end <NUM>. The terms "first end" and "proximal end" may be used interchangeably herein and the terms "second end" and "distal end" may be used interchangeably herein as they essentially refer to the same ends. The first member <NUM> may have an opening <NUM> extending from the first end <NUM> to the second end <NUM> along the longitudinal axis of the first member <NUM>. The opening <NUM> may form an interior surface <NUM>. The opening <NUM> of the first member <NUM> may also include at least one tab <NUM> extending inward from the exterior surface <NUM> of the first member <NUM> into the opening <NUM> near the second end <NUM>. The opening of the interior surface <NUM> may have a cross-sectional geometry of, for example, a relatively hexagonal or polygonal shape extending from the first end <NUM> to the at least one tab <NUM>. The opening <NUM> may also include at least one channel or slot <NUM> inset into the interior surface <NUM> and extending from the first end <NUM> toward the second end <NUM> and stopping when the channels <NUM> meet the at least one tab <NUM>. The at least one tab <NUM> may be positioned at the bottom of the at least one channel <NUM>. The at least one channel <NUM> is configured to or may receive the at least one spring member <NUM>. The bone fixation device <NUM> may include, for example, one to twelve channels <NUM> and one to twelve spring members <NUM>, as shown in <FIG>, the device <NUM> may include three channels <NUM> and three corresponding spring members <NUM>. The channels <NUM> may be positioned radially around the opening <NUM> to provide circumferential forces to facilitate equal compressive loads. For example, where the opening of the interior surface <NUM> is relatively hexagonally shaped, the channels <NUM> may be positioned on every other portion of the interior surface <NUM>, for example, on the first, third, and fifth surfaces and the second, fourth, and sixth surfaces may be generally planar. The shape of the interior surface <NUM> may also be, for example, relatively octagonal or another polygonal shape with an even number of planar surfaces or sides.

With continued reference to <FIG>, the exterior surface <NUM> of the first member <NUM> may be, for example, generally cylindrical. The exterior surface <NUM> may include a threaded portion or threaded end <NUM> and a protrusion or extension <NUM>. The protrusion <NUM> may extend away from the exterior surface <NUM> near the first end <NUM> to form an engagement portion for coupling to an insertion tool or resorbable member for insertion into a patient. The protrusion <NUM> may be of the type described above with reference to protrusion <NUM> which will not be described in detail again here for brevity sake. The threaded portion <NUM> may be positioned, for example, toward the middle of the first member <NUM> between the protrusion <NUM> and the second end <NUM> of the first member <NUM>. The threaded portion <NUM> may extend only along a portion of the exterior surface <NUM> from the protrusion <NUM> to the second end <NUM>, or alternatively, the threaded portion <NUM> may extend from the protrusion <NUM> to the second end <NUM> of the first member <NUM>.

The second member <NUM> may have a first end <NUM> and a second end <NUM> opposite the first end <NUM>, as shown in <FIG>. The second member <NUM> may be, for example, a male member. The second member <NUM> may include a cannulation or channel <NUM> extending from the first end <NUM> to the second end <NUM> through the generally central portion of the second member <NUM> along the longitudinal axis of the second member <NUM>. The cannulation <NUM> may be sized to receive a guide wire, guide pin, or the like to facilitate placement in vivo. It is also contemplated that the channel <NUM> may receive, for example, the at least one spring member <NUM>. The second member <NUM> may also have an exterior surface <NUM>. The exterior surface <NUM> may include a threaded region or threaded end <NUM> positioned near the second end <NUM> and a shaft region <NUM> extending from the threaded region <NUM> to the first end <NUM>. The threaded region <NUM> of the second member <NUM> may have, for example, a smaller diameter than the threaded portion <NUM> of the first member <NUM>. Alternatively, the threaded region <NUM> of the second member <NUM> may have the same diameter as the threaded portion <NUM> of the first member <NUM>. In addition, the threaded ends <NUM>, <NUM> may have, for example, the same threads or different threads. The threads may be selected based on the type and condition of the bone they are being inserted into to ensure the threaded ends <NUM>, <NUM> grip onto the bones or bone pieces while translation of the bones is occurring.

With continued reference to <FIG>, the shaft portion <NUM> of the second member <NUM> may include, for example, a first portion <NUM> with a generally cylindrical shape and a second portion <NUM>, having a cross-sectional hexagonal or polygonal shape. The second portion <NUM> may extend from the first end <NUM> of the second member <NUM> toward the threaded region <NUM> and the first portion <NUM> may be positioned between the threaded region <NUM> and the second portion <NUM>. The second portion <NUM> may also include at least one depression or groove <NUM> near the first end <NUM> of the second member <NUM> for insertion of the at least one tab <NUM>. The at least one depression <NUM> may include, for example, one to twelve depressions <NUM>, in the depicted embodiment three depressions <NUM> are shown, positioned radially around the exterior surface <NUM> of the shaft region <NUM>. Where the second portion <NUM> of the shaft region <NUM> has, for example, a polygonal shape with an even number of sides, such as, a hexagon, octagon, or the like, the depressions <NUM> may be positioned on every other side of the polygonal shape. The depressions <NUM> may be positioned and be configured to enable insertion of the at least one tab <NUM> of the first member <NUM>. The second portion <NUM> may also include at least one channel or slot <NUM> extending from the at least one depression <NUM> toward the first portion <NUM>. The at least one channel <NUM> may be inset into the exterior surface <NUM>. The at least one channel <NUM> may include a plurality of teeth or grooves <NUM> positioned relatively perpendicular to the longitudinal axis of the channel <NUM>. The grooves <NUM> may be sized to receive the at least one locking member <NUM>, as described in greater detail below. The at least one channel <NUM> may at least partially receive the at least one spring member <NUM>, as shown in <FIG>.

The second member <NUM> may include, for example, any number of channels <NUM> and any number of spring members <NUM>, such as, one to twelve channels <NUM> and one to twelve spring members <NUM>. In the illustrated embodiment, the bone fixation device includes three channels <NUM> and three spring members <NUM>. The at least one channel <NUM> may be positioned radially around the second portion <NUM> of the exterior surface <NUM>. The exterior surface <NUM> of the second portion <NUM> of the shaft region <NUM> may have a shape corresponding to the shape of the opening <NUM> in the first member <NUM>. For example, where the exterior surface <NUM> of the second portion <NUM> of the shaft region <NUM> has a relatively hexagonal cross-sectional shape, the channels <NUM> may be positioned on every other portion of the exterior surface <NUM>, for example, on the first, third and fifth surfaces and the second, fourth and sixth surfaces may be generally planar. The cross-sectional shape of the exterior surface <NUM> may also be, for example, relatively octagonal or another polygonal shape with any number of sides. The exterior surface <NUM> may have any shape with an even or odd number of sides and a spring channel <NUM> may be located in one or more of the sides of the exterior surface <NUM>. At least one spring member <NUM> will be positioned in the at least one spring channel <NUM>.

The bone fixation device <NUM> may have, for example, the at least one spring member <NUM> that is positioned between the at least one channel <NUM> of the first member <NUM> and the at least one channel <NUM> of the second member <NUM> when the second member <NUM> is inserted into the first member <NUM>. In the depicted embodiment, at least three spring members <NUM> are positioned between the three channels <NUM> and the three channels <NUM>. The at least three spring members <NUM> may be, for example, three single springs or three sets of at least two springs. The spring members <NUM> may be, for example, spiral springs or straight springs as described in greater detail above with respect to bone fixation device <NUM>.

The at least one locking member <NUM>, as shown in <FIG>, may be sized and shaped to be positioned between the channel <NUM> of the first member <NUM> and the channel <NUM> of the second member <NUM>. The at least one locking member <NUM> may also be positioned proximal to the at least one tab <NUM> of the first member <NUM> and distal to the at least one spring member <NUM>. The at least one locking member <NUM> may be, for example, a ratcheting locking member <NUM> which allows the first and second members <NUM>, <NUM> to be moved in a first direction with respect to each other, as shown in <FIG>, but locks the first and second members <NUM>, <NUM> together and prevents them from moving in a second opposite direction, as shown in <FIG>. The at least one locking member <NUM> engages the grooves <NUM> in the at least one channel <NUM> of the second member <NUM> at a first end and contacts the at least one channel <NUM> of the first member <NUM> at a second end to secure the first and second members <NUM>, <NUM> in a desired position. The at least one locking member <NUM> may be, for example, rotatably connected to the at least one channel <NUM> of the first member <NUM>. The at least one locking member <NUM> may be, for example, rounded on a first end and planar on a second opposite end. It is also contemplated that the locking member <NUM> may be, for example, a conical shaped spring washer or another alternative shape which allows for the locking members <NUM> to move in a first direction and lock in a second direction. The locking members <NUM> may, for example, prevent the first member <NUM> and second member <NUM> from lengthening after compression of the bone fixation device <NUM> is complete.

The at least one tab <NUM> and at least one locking member <NUM> of the bone fixation device <NUM> may be, for example, used in place of the ring member <NUM> in the fixation device <NUM> and the fixation device <NUM> as described above with respect to bone fixation device <NUM>.

By way of specific example, the bone fixation device <NUM> may be a screw. The screw <NUM> may be, for example, a <NUM> screw with the opening <NUM> of the first member <NUM> having a width at the first end <NUM> of approximately <NUM> to <NUM> and a diameter at the second end <NUM> of approximately <NUM> to <NUM> and the shaft region <NUM> of the second member <NUM> having, for example, an outer diameter of approximately <NUM> to <NUM>.

A method of assembling the bone fixation device <NUM> may include, for example, obtaining a first member, a second member, at least one spring member, and at least one locking member. The method may also include, for example, inserting a portion of the second member into the first member. The method may further include, for example, positioning the at least one spring member between the first member and the second member and positioning the at least one locking member between the first member and the second member distal to the at least one spring member. Finally, the method may include sliding the second member into the first member to a first position.

The methods of using the bone fixation device <NUM> is similar to as described above with reference to the methods of using the bone fixation device <NUM> and which will not be described aga revity sake.

Claim 1:
A bone fixation device (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising:
a first member (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising a proximal end of the device;
a second member (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising a distal end of the device; and
at least one elastic element (<NUM>) positioned between the first member and the second member, characterized by
a member coupling the first member to the second member and providing a base for engagement with the elastic element during compression and expansion of the elastic element,
wherein the first member and the second member are moveable relative to each other to lengthen the device, and
wherein lengthening of the device compresses the elastic element.