Patent Description:
Fractures of the femur often occur in the femoral neck and intertrochanteric regions. Such fractures may be treated with screws or other fixation devices inserted into or through a bone to stabilize and fix the positioning of different portions of the bone relative to one another after they have been placed into corrective alignment. Trochanteric bone fixation treatments often comprise the insertion of an intramedullary nail into a medullary cavity of a bone and the subsequent insertion of a bone fixation nail into a condylar portion of the bone at an angle relative to the intramedullary nail (i.e., along an axis of the trochanter). <CIT> teaches an apparatus for and methods of inserting implants, wherein the apparatus includes a handle portion and a body portion attached to the handle portion and defining a longitudinal axis. The body portion includes an outer tubular member fixed relative to the handle portion for rotation therewith about the longitudinal axis. The outer tube member has first implant engaging structure adjacent a distal end. An inner tubular member is disposed at least partially within the outer tubular member and is mounted for longitudinal motion relative to the outer tubular member. Second implant engaging structure is positioned adjacent a distal end of the inner tubular member. The body portion further includes an inner shaft, coaxially mounted at least partially within the inner tubular member for independent rotation relative to the inner and outer tubular members, the inner shaft having third implant engaging structure adjacent a distal end. In a method for inserting an implant having a hollow portion with a closed distal end and a removable cap, the first, second and third implant engaging structures are attached to the implant with at least one of the engaging structure attached to the removable cap and another of the engaging structure attached to the hollow portion. The implant is inserted into the desired surgical location.

According to an aspect of the present application, a system for engaging a proximal end of an intramedullary nail is provided. The system comprises a driver having a handle extending along a longitudinal axis of the driver from a proximal end to a distal end and having a handle channel extending longitudinally therethrough. The driver also includes a shaft extending through the handle channel from a proximal end to a distal end along the longitudinal axis having a shaft channel extending longitudinally therethough. The distal end of the shaft extends distally from the handle. The distal end of the shaft forms a driving element. The driver further includes a retention pin slidably received in the shaft channel and extending from a proximal end to a distal end along the longitudinal axis. The distal end of the retention pin comprises threading. The retention pin also includes a lumen extending longitudinally therethrough. The system also comprises an endcap having a lumen extending therethrough. The end cap comprises a body configured to engage a channel of the intramedullary nail, and a head portion configured to receive the driving element therein and to reversibly lock the head portion to the shaft. The head portion of the end cap comprises threading configured to threadedly engage a corresponding threading of the retaining pin. The system further comprises a guidewire slidably inserted through the lumen of the retention pin and the lumen of the endcap to align the driving element to the head portion of the endcap.

These and other aspects of the invention will become apparent to those skilled in the art after a reading of the following detailed description of the invention, including the figures and appended claims.

The present disclosure may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. It should be noted that the terms "proximal" and "distal," as used herein are intended to refer to a direction toward (proximal) and away from (distal) a user of the device.

1a-c and <NUM> shows a driver <NUM> for engaging an endcap <NUM> couplable to a proximal end <NUM> of an intramedullary nail <NUM>. The driver <NUM> includes a handle <NUM> extending along a longitudinal axis L1 from a proximal end <NUM> to a distal end <NUM>. The handle <NUM> has a handle channel <NUM> that extends longitudinally from the proximal end <NUM> to the distal end <NUM> through the handle <NUM> along the longitudinal axis L1. The handle <NUM> may have any suitable size and shape for being held within the palm of a user's hand to manually manipulate the handle <NUM>. Preferably, the handle <NUM> is suitably sized and shape to provide an ergonomic shape for a user to hold within the palm of his hand and to rotate the driver <NUM> by hand.

In an exemplary embodiment, the handle <NUM> has an elongated shape. As shown in <FIG>, the handle <NUM> has an elongated shape that is tapered such that a diameter of the handle <NUM> is reduced from an enlarged portion <NUM> (located proximal to the distal end <NUM>) to the distal end <NUM>. In particular, the handle <NUM> has a bulb shape. Specifically, the handle <NUM> increases from a first diameter at the proximal end <NUM> to a maximum diameter at the enlarged portion <NUM> and includes a tapered portion <NUM> adjacent the distal end <NUM>, the tapered portion <NUM> being formed to aid in ergonomic use of the handle <NUM> in a hand of a user.

The driver <NUM> also includes a shaft <NUM> that extends through the handle channel <NUM> from a proximal end <NUM> to a distal end <NUM> along the longitudinal axis L1. The shaft <NUM> is co-axial with the handle <NUM> along the longitudinal axis L1. In some embodiments, the shaft <NUM> has a cross-sectional diameter from about <NUM> to about <NUM> in a plane orthogonal to the longitudinal axis L1 between the proximal end <NUM> and a portion proximal to a driving element <NUM> located at the distal end <NUM> (e.g., along a plane A-A' as shown in <FIG>). The shaft <NUM> has a shaft channel <NUM> extending longitudinally from the proximal end <NUM> to the distal end <NUM> through the shaft <NUM> along the longitudinal axis L1. The shaft channel <NUM> is co-axial with the shaft <NUM> and defines an inner diameter of an interior surface of the shaft channel <NUM>. In some embodiments, the inner diameter of the shaft <NUM> is from about <NUM> to about <NUM>. As shown in <FIG>, the shaft <NUM> is longer than the handle <NUM> such that the distal end <NUM> of the shaft <NUM> extends distally further than the distal end <NUM> of the handle <NUM>. For example, the shaft <NUM> extends from about <NUM> to about <NUM>, distally further than the distal end <NUM> of the handle. The proximal end <NUM> of the shaft <NUM> may be fixed anywhere along a length of the handle channel <NUM>. For example, as shown in <FIG>, the proximal end <NUM> of the shaft <NUM> is positioned at the proximal end <NUM> of the handle <NUM>. In another example, the proximal end <NUM> of the shaft <NUM> is positioned within the handle channel <NUM>, between the proximal and distal ends <NUM>, <NUM> of the handle <NUM>.

In one embodiment, the handle 102a may be formed as an elastomeric (e.g., silicone) molding over the shaft <NUM>, for example, as shown in <FIG>. The elastomeric molding is formed over the shaft <NUM> such that a handle channel <NUM> is defined therein around the shaft <NUM>. The elastomeric molding provides a soft material that reversibly deforms to provide an ergonomic shape for a user to hold within the palm of his hand. In addition, the elastomeric molding increases friction between the surface of the handle 102a and the palm of the user's hand to provide a handle 102a that is easy and comfortable to hold in the hand of the user. <FIG> shows a side view of an elastomeric molded handle 102a over a portion of a shaft <NUM>, and <FIG> shows a side view of the elastomeric molded handle 102a from a side opposite that shown in <FIG>. As can be seen in <FIG>, the handle 102a is molded over the shaft <NUM> in a tapered shape where a width of the handle <NUM> increase from a first diameter at the proximal end <NUM> to a maximum width at an enlarged portion 110a of the handle 102a and includes a tapered portion 112a having a narrower width adjacent the distal end <NUM>. <FIG> shows a cross-sectional view of the embodiment of <FIG> along a plane along the longitudinal axis L1 (e.g., along a plane B-B' as shown in <FIG>. As can be seen in <FIG>, the height of the handle 102a in this exemplary embodiment between the opposing sides shown in <FIG> is constant along the length of the handle 102a.

The shaft <NUM> includes one or more clamps <NUM> located at or near the enlarged portion <NUM> of the handle <NUM> extending along a plane transverse to the longitudinal axis L1. The clamp <NUM> may include any suitable structure for clamping on to the shaft <NUM> and extending transverse to the longitudinal axis L1 such that rotation of the silicon molded handle <NUM> by a user transfers torque to the shaft <NUM>. As shown in the embodiments of <FIG>, the clamp <NUM> is placed onto the shaft <NUM> prior to molding over both the shaft <NUM> and the clamp <NUM> with an elastomeric molding to form the handle <NUM>. The clamp <NUM> is movable between an open configuration, shown in <FIG>, and a locked configuration, shown in <FIG>. The clamp <NUM> comprises a first portion <NUM> and a second portion <NUM> slidably engaged with one another defining a slot <NUM> therebetween. In the open configuration shown in <FIG>, the slot <NUM> is suitably sized and shaped to slidably receive the shaft <NUM> therein. The first and seconds portions <NUM> and <NUM> are configured to move towards one another (as shown by the arrows in <FIG>) to the locked configuration shown in Fig. If to reduce the size of the slot <NUM> such that the slot <NUM> lockingly engages the shaft <NUM> by pushing the first and second portions <NUM>, <NUM> towards each other to securely clamp against the exterior of the shaft <NUM>. The handle <NUM> may further include additional surface features (not shown) configured to enhance a grip of the handle <NUM> by the user.

The distal end <NUM> of the shaft <NUM> forms a driving element <NUM> that is suitably sized and shaped to be inserted into a head portion <NUM> of the endcap <NUM>. In particular, the driving element <NUM> is suitably sized and shaped to non-rotatably engage a recess <NUM> of the head portion <NUM> of the end cap <NUM>. In one embodiment, the driving element <NUM> is suitably sized and shaped to non-rotatably engage the recess <NUM> so that manipulation of the handle <NUM> while the driving element <NUM> is engaged with the recess <NUM> drives the body portion <NUM> of the endcap <NUM> into the channel <NUM> of the intramedullary nail <NUM>. The driving element <NUM> is configured to non-rotatably engage the head portion <NUM> of the endcap <NUM> such that rotation of the handle <NUM> transfers torque through the shaft <NUM> to the driving element <NUM>. Torque applied to the handle <NUM> rotatably drives the endcap <NUM> into the channel <NUM> of the intramedullary nail <NUM>.

The driving element <NUM> shown in <FIG> is in the shape of an elongated cylinder with a series of circumferentially spaced projections <NUM>. As shown in <FIG>, the projections <NUM> are evenly spaced about the circumference of the cylinder. The projections <NUM> in this embodiment are rounded or curved and extend along a part of or an entire length of the driving element <NUM> defining therebetween longitudinal grooves <NUM> that extend along a part of or an entire length of the driving element <NUM>. The projections <NUM> form protruding surface features to non-rotatably engage with the head portion <NUM> of the endcap <NUM>. Alternatively, the driving element may have an elongated shape with a polygonal cross-section or a substantially polygonal cross-section, for example, a cross-section that is substantially hexagonal (e.g., a hex-key) in a plane orthogonal to a longitudinal axis L1 of the shaft <NUM>.

The driver <NUM> further includes a retention pin <NUM> that extends through the shaft channel <NUM> from a proximal end <NUM> to a distal end <NUM> along the longitudinal axis L1. The retention pin <NUM> is coaxial with the shaft <NUM> along the longitudinal axis L1. The retention pin <NUM> is sized and shaped to be slidable and/or rotatable within the shaft channel <NUM>. In some embodiments, the retention pin <NUM> is sized and shaped to correspond to the size and shape of the shaft channel <NUM>, for example, a cylindrical shape. The cylindrical shape of the retention pin <NUM> may have a cross-sectional outer diameter from about <NUM> to about <NUM> and inner diameter of about <NUM> to about <NUM>, in a plane orthogonal to the longitudinal axis L1. The retention pin <NUM> defines a lumen <NUM> extending longitudinally from the proximal end <NUM> to the distal end <NUM> along the longitudinal axis L1. The lumen <NUM> of this embodiment is co-axial with the retention pin <NUM> and defines a thickness d (e.g., shown in <FIG> and <FIG>) from an exterior surface of the retention pin <NUM> to an interior surface of the lumen <NUM>. In some embodiments, the thickness d of the retention pin is from about <NUM> to about <NUM>.

As shown in <FIG>, the proximal end <NUM> of the retention pin <NUM> extends proximally beyond the proximal end <NUM> of the shaft <NUM>. The retention pin <NUM> may be slidably movable or longitudinally fixed with in the shaft channel <NUM>. In some embodiments, the distal end <NUM> of the retention pin <NUM> extends distally beyond the distal end <NUM> of the shaft <NUM>. In other embodiments, the distal end <NUM> of the retention pin <NUM> is slidably movable between a retracted configuration in which the distal end <NUM> is positioned within the shaft channel <NUM> and an extended configuration in which the retention pin <NUM> extends distally beyond the distal end <NUM> of the shaft <NUM> so that it may engage with the head portion <NUM> of the endcap <NUM>. The distal end <NUM> of the retention pin <NUM> comprises a surface feature configured to reversibly lock the shaft <NUM> to the head portion <NUM> of the endcap <NUM>. In particular, the surface feature is suitably sized and shaped to reversibly engage a corresponding feature within the head portion <NUM> of the endcap <NUM>. When the surface feature is engaged with the head portion <NUM>, the endcap <NUM> is lockingly coupled to the distal end <NUM> of the retention pin <NUM>. For example, the surface feature in this embodiment comprises threading <NUM> for engaging corresponding threading <NUM> in the head portion <NUM> of the endcap <NUM>.

The driver <NUM> further includes a knob <NUM> rotatably connected to the proximal end <NUM> of the shaft <NUM>. Rotation of the knob <NUM> about the longitudinal axis L1 rotates the retention pin <NUM> to lock and unlock the retention pin <NUM> from the head portion <NUM> of the endcap <NUM>. The knob <NUM>, in this embodiment, is rotatably connected to the shaft <NUM> via an axle mechanism <NUM> fixedly attached to a proximal portion of the shaft <NUM>. As shown in <FIG>, the axle mechanism <NUM> is inserted into a proximal portion of the shaft channel <NUM> and rotatably fixed therein. The axle mechanism <NUM> includes an axle channel <NUM> extending longitudinally through the axle mechanism <NUM> to receive the retention pin <NUM>. The axle mechanism <NUM> is rotatably connected to the knob <NUM>. The knob <NUM> is also non-rotatably connected to a proximal end <NUM> of the retention pin <NUM> such that rotation of the knob <NUM> in a desired direction about the longitudinal axis L1 rotates the retention pin <NUM> in the same direction.

For example, <FIG> shows that the proximal end <NUM> of the retention pin <NUM> is embedded within the knob <NUM>. The knob <NUM> further includes a knob channel <NUM> aligned with the lumen <NUM> of the retention pin <NUM> to permit a guidewire <NUM> to extend through the knob channel <NUM> into the lumen <NUM> of the retention pin <NUM>. The knob <NUM> may have any suitable size and shape for being held between the fingertips of a user's hand to facilitate manual manipulation of the knob <NUM>. Preferably, the knob <NUM> is suitably sized and shaped to provide an ergonomic shape for a user to pinch between an index finger and a thumb to manipulate, or rotate, the knob <NUM> by hand. The knob <NUM> may include additional surface features (not shown) configured to enhance a grip of the knob <NUM> by the fingertips of a user as would be understood by those skilled in the art.

<FIG> shows an endcap <NUM> configured to be inserted into a proximal opening <NUM> of a channel <NUM> in the intramedullary nail <NUM> to close the proximal opening <NUM> of the channel <NUM> to prevent bone ingrowth into the channel <NUM>. The endcap <NUM> is configured to reversibly engage and disengage an interior surface of the channel <NUM> in the intramedullary nail <NUM> via any suitable engagement structure, such as, for example, threading <NUM> configured to engage corresponding threading within the interior surface of the channel <NUM>. The endcap <NUM> extends from a proximal end <NUM> to a distal end <NUM> and includes a body portion <NUM> and a head portion <NUM> proximal of the body portion <NUM>. The body portion <NUM> extends from a proximal end <NUM> thereof to the distal end <NUM> of the endcap <NUM>. The head portion <NUM> extends proximally from the proximal end <NUM> of the body portion <NUM>. The endcap <NUM> further includes a lumen <NUM> extending from the proximal end <NUM> to the distal end <NUM> along a longitudinal axis L2 thereof. The lumen <NUM> being configured to receive a guide wire <NUM> therethrough.

The body portion <NUM> of the endcap <NUM> is configured to be inserted into and engage a channel <NUM> of an intramedullary nail <NUM>. In particular, the distal end <NUM> is suitably sized and shaped to be inserted into a proximal opening <NUM> of a channel <NUM> in the intramedullary nail <NUM> and fixedly engage an interior of the channel <NUM> of the intramedullary nail <NUM>. The body portion <NUM> may include any suitable engagement structure, e.g., threading <NUM>, snap fasteners, adhesives or screws to attach endcap <NUM> to the channel <NUM> of the intramedullary nail <NUM>. In some embodiments, the body portion <NUM> includes at least a portion having a threading <NUM> configured to threadedly engage the interior of the channel <NUM> of the intramedullary nail <NUM>. The threading <NUM> may extend along a part of or an entire longitudinal length of the body portion <NUM>. The threading <NUM> is configured to mate with corresponding threading in the interior of the channel <NUM> of the intramedullary nail <NUM> as the endcap <NUM> is driven into the channel <NUM> of the intramedullary nail <NUM>, to secure the endcap <NUM> to the proximal end <NUM> of the intramedullary nail <NUM>.

The head portion <NUM> of the endcap <NUM> comprises a recess <NUM> for engaging the driver <NUM>, in particular, the driving element <NUM> of the shaft <NUM>. For example, the recess <NUM> has a size and shape corresponding to that of the driving element <NUM> for receiving and engaging the driving element <NUM>. The recess <NUM> is suitably sized and shaped to engage the driving element <NUM> so that manipulation of the driver <NUM> while the driving element <NUM> is engaged with the recess <NUM> drives the endcap <NUM> into or out of the channel <NUM> of the intramedullary nail <NUM>. More particularly, the recess <NUM> is configured to non-rotatably engage the driving element <NUM> such that rotation of the shaft <NUM> transfers torque from the shaft <NUM> through the head portion <NUM> to drive the body portion <NUM> of the endcap <NUM> into the channel <NUM>.

The recess <NUM> also includes a corresponding surface feature suitably sized and shaped to reversibly engage the surface feature at the distal end <NUM> of the retention pin <NUM> such that the head portion <NUM> of the endcap <NUM> reversibly locks to the shaft <NUM>. For example, the recess <NUM> includes an indentation <NUM> extending distally from the recess <NUM> along the longitudinal axis L2. In some embodiments, the indentation <NUM> is a cylindrical channel having corresponding threading <NUM> configured to mate with the threading <NUM> at the distal end <NUM> of the retention pin <NUM> as the retention pin <NUM> extends distally past the distal end <NUM> of the shaft <NUM> and is driven into the indentation <NUM> to secure the endcap <NUM> to the distal end <NUM> of the retention pin <NUM>. The indentation <NUM> is suitably sized and shaped to engage the distal end <NUM> of the retention pin <NUM> so that rotation of the knob <NUM> rotates the retention pin <NUM> to drive the threading <NUM> located at the distal end <NUM> of the retention pin <NUM> to lockingly engage the corresponding threading <NUM>.

When the threading <NUM> of the retention pin <NUM> locks to the corresponding threading <NUM> of head portion <NUM>, the endcap <NUM> is lockingly coupled to the distal end <NUM> of the retention pin <NUM> so that manipulation of the shaft <NUM> does not accidentally disengage the head portion <NUM> from the driver <NUM>. This minimizes the risk that the endcap <NUM> will be accidentally dropped during implantation. The threading <NUM> of the retention pin <NUM> is suitably sized and shaped to disengage from the corresponding threading <NUM> by rotating the knob <NUM> in a reverse direction to rotatably withdraw the distal end <NUM> of the retention pin <NUM> from the indentation <NUM> to unlock the retention pin <NUM> from the head portion <NUM> after the endcap <NUM> has been driven to a desired position in the channel <NUM> of the intramedullary nail <NUM>.

The driver <NUM> and the endcap <NUM> as described above may be provided along with a guidewire <NUM> as part of a system <NUM> for engaging a proximal end of an intramedullary nail <NUM>. As can be seen in an exemplary embodiment shown in <FIG>, the endcap <NUM> may be installed at the proximal end <NUM> of the intramedullary nail <NUM> by inserting a guidewire <NUM> into the channel <NUM> of the intramedullary nail <NUM> and sliding the endcap <NUM> over the guidewire <NUM> via lumen <NUM> towards a desired position over the proximal end <NUM> of the intramedullary nail <NUM>. The driver <NUM> is also configured to receive the guidewire <NUM> therethrough and slide into position to engage the head portion <NUM> of the endcap <NUM>. Specifically, when the system is in use, the guidewire <NUM> is slidably inserted from the proximal end of the driver <NUM> through the knob channel <NUM> and the lumen <NUM> to the distal end <NUM> of the retention pin <NUM> and also through the recess <NUM> and lumen <NUM> of the endcap <NUM>. The driver <NUM> and the endcap <NUM> are slid into position along the guidewire <NUM> to engage the driver <NUM> with the endcap <NUM> such that the longitudinal axis L1 of the driver <NUM> and the longitudinal axis L2 of the endcap <NUM> are substantially aligned, or aligned within the predetermined angular range of tolerance.

Once the driver <NUM> has been inserted into the recess <NUM> of the endcap <NUM> to engage the head portion <NUM>, the knob <NUM> is rotated to drive the threading <NUM> of the retention pin <NUM> into the corresponding threading <NUM> of the head portion <NUM> to lockingly engage the distal end <NUM> of the retention pin <NUM> to the endcap <NUM>. Once the endcap <NUM> has been securely locked to the driver <NUM>, manipulation (e.g., rotation) of the handle <NUM> translates applied forces and/or torque to the endcap <NUM>. In particular, the driver <NUM> may be manipulated to drive the body portion <NUM> of the endcap <NUM> into the channel <NUM> of the intramedullary nail <NUM>. The endcap <NUM> may be driven into the channel <NUM> of the intramedullary nail <NUM> such that a portion of or an entire longitudinal length of the body portion <NUM> of the endcap <NUM> lies within the channel <NUM> when it is fully inserted. In some embodiments, only a portion of the length of the body portion <NUM> is inserted and engaged with the channel <NUM> such that the endcap <NUM> provides a proximal extension to the intramedullary nail <NUM>.

In certain embodiments, the shaft <NUM> and/or the retention pin <NUM> are formed of a material having a rigidity sufficient to resist deformation of the shaft during use. For example, the shaft <NUM> has a rigidity sufficient to resist twisting and/or bending upon application of forces and/or torque of an expected magnitude via the handle <NUM> to drive the body portion <NUM> of the endcap <NUM> into the channel <NUM> of the intramedullary nail <NUM>. In addition or in the alternative, the retention pin <NUM> has a rigidity sufficient to resist twisting and/or bending when the knob <NUM> is rotated to drive the threading <NUM> of the retention pin <NUM> into the corresponding threading <NUM> of the head portion <NUM>. The rigidity of the shaft <NUM> and/or the retention pin <NUM> resists yielding to applied forces and/or torque such that the distal end <NUM> of the shaft <NUM> and/or the distal end <NUM> of the retention pin <NUM> is easily substantially aligned to engage with the head portion <NUM> of the endcap <NUM> when the device is in use, in particular, to engage the threading <NUM> of the retention pin <NUM> with the corresponding threading <NUM> of the head portion <NUM>. The shaft <NUM> and/or retention pin <NUM> may be formed from any suitable material that provides the desired rigidity, such as, for example, stainless steel (e.g., <NUM> stainless steel, <NUM> stainless steel, Custom <NUM> stainless steel, <NUM> stainless steel, or <NUM> stainless steel.

In other embodiments, a driver <NUM> may comprise a shaft <NUM> and a retention pin <NUM> that are flexible and reversibly movable between a relaxed configuration and a deformed configuration. The driver <NUM> shown in <FIG> and <FIG> is substantially similar to the driver <NUM> of Figs. 1a-c and <FIG>, with like elements referenced with like reference numerals. In this alternative embodiment, the shaft <NUM> and the retention pin <NUM> are movable between a relaxed configuration (shown in <FIG>) in which the shaft <NUM> and the retention pin <NUM> lie along the longitudinal axis L3, and a deformed configuration (shown in <FIG>) in which the shaft <NUM> and the retention pin <NUM> are elastically deformed to extend along a curved path away from the longitudinal axis L3 to the endcap <NUM>. This allows a user to manipulate the endcap <NUM> in the same manner described above even when the particular anatomy of a patient or the geometry of the surgical approach render it difficult or impossible to obtain a straight line of approach of the driver <NUM> to the endcap <NUM>.

The shaft <NUM> and the retention pin <NUM> of this embodiment may be deformed when the device <NUM> is used to insert the endcap <NUM> into an intramedullary nail <NUM> for fixation of a femur <NUM>. The shaft <NUM> and the retention pin <NUM> may be deformed upon application of force to push the shaft <NUM> and the retention pin <NUM> to bend along a curved path, for example, for circumventing the iliac crest <NUM> during use. When the force is removed from the shaft <NUM> and the retention pin <NUM>, the shaft <NUM> and the retention pin <NUM> return to the relaxed configuration. In one example, the flexibility of the shaft <NUM> and/or the retention pin <NUM> varies along a length thereof. For example, the shaft <NUM> and/or retention pin <NUM> may comprise a plurality of regions, each region having a different degree of flexibility.

In one exemplary embodiment, the driver <NUM> may comprise a shaft <NUM> that includes surface features that increase flexibility of the shaft <NUM> such that the shaft <NUM> is movable between a relaxed configuration and a deformed configuration. The driver <NUM> shown in <FIG> is substantially similar to the driver <NUM> of Figs. 1a-c and <FIG>, with like elements referenced with like reference numerals. In this exemplary embodiment, the shaft <NUM> includes aligned groove(s) <NUM> wrapping around an external surface of the shaft <NUM> and extending along at least a portion of the shaft <NUM> to impart increased flexibility to the shaft <NUM>. For example, the grooves <NUM> may extend along a length of the shaft <NUM> (e.g., <NUM> of the shaft <NUM>) such that the shaft <NUM> is sufficiently flexible for bending up to <NUM>° away from the longitudinal axis L1, as shown in <FIG>. As shown in <FIG>, the grooves <NUM> may comprise laser cut windings wrapping around an external surface of the shaft <NUM>. The laser cut windings may be angled to a plane along the longitudinal axis L1 and substantially parallel to one another.

In one exemplary embodiment shown in <FIG>, the grooves <NUM> extend at a <NUM>° angle from the plane along the longitudinal axis L1. The grooves <NUM> may have any suitable shape and pattern. As shown in <FIG>, the grooves <NUM> are cut in an interlocking pattern having a wing <NUM> extending transverse to the angle of the windings, the wing <NUM> comprising a widened portion <NUM> and a narrow neck portion <NUM>. The narrow neck portion <NUM> configured to interlock with the widened portion <NUM> of the next wing <NUM> in the interlocking pattern. The widened portion <NUM> has a width x<NUM> and the narrow neck portion <NUM> has a width x<NUM> where x<NUM> > x<NUM>. For example, the widened portion <NUM> has a width x<NUM> from about <NUM> to <NUM> and the narrow neck portion <NUM> has a width x<NUM> a width from about <NUM> to <NUM>. The windings may be spaced apart by a distance y between each of the windings, as shown in <FIG>. The distance y is, for example, from about <NUM> to about <NUM>. In one particular embodiment (not shown), the shaft <NUM> may have a plurality of regions, each region having a different degree of flexibility provided by a different distance y between the windings, where a smaller distance y provides an increase in flexibility to the shaft <NUM>.

Claim 1:
A system for engaging a proximal end of an intramedullary nail (<NUM>), comprising:
(i) a driver (<NUM>) comprising
a handle (<NUM>) extending along a longitudinal axis (L1) of the driver (<NUM>) from a proximal end (<NUM>) to a distal end (<NUM>) and having a handle channel (<NUM>) extending longitudinally therethrough,
a shaft (<NUM>) extending through the handle channel (<NUM>) from a proximal end (<NUM>) to a distal end (<NUM>) along the longitudinal axis (L1) having a shaft channel (<NUM>) extending longitudinally therethough, the distal end (<NUM>) of the shaft (<NUM>) extending distally from the handle (<NUM>), the distal end (<NUM>) of the shaft (<NUM>) forming a driving element (<NUM>), and
a retention pin (<NUM>) slidably received in the shaft channel (<NUM>) and extending from a proximal end (<NUM>) to a distal end (<NUM>) along the longitudinal axis (L1), the distal end (<NUM>) of the retention pin (<NUM>) comprises threading, the retention pin (<NUM>) including a lumen extending longitudinally therethrough;
(ii) an endcap (<NUM>) having a lumen extending therethrough comprising
a body (<NUM>) configured to engage a channel (<NUM>) of the intramedullary nail (<NUM>), and
a head portion (<NUM>) configured to receive the driving element (<NUM>) therein and to reversibly lock the head portion (<NUM>) to the shaft (<NUM>), the head portion (<NUM>) comprising threading configured to threadedly engage a corresponding threading of the retaining pin (<NUM>); and
(iii) a guidewire (<NUM>) slidably inserted through the lumen of the retention pin (<NUM>) and the lumen of the endcap (<NUM>) to align the driving element (<NUM>) to the head portion (<NUM>) of the endcap (<NUM>).