Patent Description:
One such device is a femoral, intramedullary nail. Femoral nails are elongate structures that are inserted into an intramedullary canal through either the proximal femur or distal femur. Such nails are typically bent along their respective lengths in an attempt to follow the natural curvature of a human long bone, such as the anterior bow found in virtually all human femurs.

However, since anatomy varies from patient to patient, it has been difficult to develop appropriate femoral nail geometries that are suitable for the entire patient population. This difficulty has been confirmed by recent database analyses of femurs that have found that certain curvatures of the human femur are greater than originally considered. In this regard, current femoral nails are generally disproportionately curved relative to the femurs into which they are implanted. This disproportionality may result in impingement of the femoral cortex during implantation potentially resulting in fracture and also malalignment of the femoral nail which can be uncomfortable for the patient and result in less than desirable outcomes. Therefore, further improvements are desirable.

<CIT> discloses an intramedullary nail, devices and methods for implantation, which are particularly useful in pediatric cases. The intramedullary nail is a one-piece item with a proximal portion, a medial portion and a distal portion and a continuous cannula that extends through each of those portions. The proximal portion has a longitudinal axis and an end with at least one finger extending parallel to that longitudinal axis from an end surface. The proximal portion has an internal thread along the cannula extending from the end surface toward the medial portion and first and second linear channels formed through the proximal portion. The first and second channels have respective first and second openings on one side of the proximal portion and a common third opening across from the first and second openings.

A femoral nail is disclosed that includes a proximal section, a distal section, and an intermediate section. The proximal and distal sections extend along their own axes and are substantially straight. The intermediate section is disposed between the proximal section and distal section and includes a first curved portion, a straight portion, and a second curved portion. The straight portion is disposed between the first and second curved portions. The second curved portion is curved in a first plane and has a radius that substantially matches a radius of an anterior bow of a patient's femur as may be approximated based upon a database population analysis. The first curved portion is curved in the first plane and also in a second and third plane. The second plane intersects the first plane at an oblique angle, and the third plane is a resultant of this oblique angle and the magnitude of the bends of the nail in the first and second planes. Such multiplane curvature has been determined by database analysis to provide optimal fit for the general patient population and to reduce incidence of femoral cortex impingement.

In one aspect of the present disclosure, a femoral nail includes a proximal portion configured to engage a driving tool for driving the femoral nail into a femur, a distal portion remote from the proximal portion, and an intermediate portion disposed between the proximal end and distal end. The intermediate portion includes a plurality of bends such that a first bend is in a first plane, a second bend is in a second plane, and a third bend is in a third plane. The first and second planes intersect at an oblique angle relative to each other. The third bend is a resultant of the first and second bends and has a magnitude greater than the first and second bends.

Additionally, the distal end may be straight and may include a plurality of through-holes extending through the distal end in a direction transverse to a distal end axis. The first plane may be greater than <NUM> degrees and smaller than <NUM> degrees relative to the second plane. In one example, the first plane is preferably <NUM> degrees relative to the second plane. The first plane may extend in an anterior-posterior direction, and the second plane may extend substantially in a medial-lateral direction.

Continuing with this aspect, the first bend may be <NUM> degrees, the second bend may be <NUM> degrees, and the third bend may be greater than <NUM> degrees. The intermediate portion may have a radius of curvature in the first plane. Also, the proximal end of the femoral nail may include a plurality of through-holes extending therethrough. At least a first and second through-hole of the plurality of through-holes may have respective first and second through-hole axes that lay in the second plane. Furthermore, the proximal end may include at least one rotational alignment characteristic for indicating a rotational alignment of the femoral nail relative to a femur. The rotational alignment characteristic may be rotationally offset from the third plane by an acute angle. The acute angle may be less than <NUM> degrees. The rotational alignment characteristic may be an engagement notch configured to engage the driving tool. Also, the third plane may intersect the second plane at an acute angle less than <NUM> degrees. Each of the bends may be an equal distance from a terminal end of the proximal portion.

In another aspect of the present disclosure, a femoral nail includes a proximal section that has a longitudinal axis extending along its length, a distal section remote from the proximal section, and an intermediate section disposed between the proximal section and distal section. The intermediate section has a straight portion and first bent portion. The first bent portion is disposed between the straight portion and the proximal section. The first bent portion is bent in first, second, and third planes such that a longitudinal axis of the straight portion is oriented relative to a longitudinal axis of the proximal section by first, second, and third angles within the respective first, second, and third planes, and wherein the first, second, and third angles differ from one another.

Additionally, the intermediate section may also include a second bent portion disposed between the straight portion and distal section. The second bent portion may be bent in the first plane. The second bent portion may have a radius of curvature of <NUM>-<NUM>. The proximal and distal sections may be straight along their respective lengths. The magnitude of the third angle may be a resultant of the respective magnitudes of the first and second angles and the orientation of the first and second planes relative to each other. The first angle may be <NUM> degrees, the second angle may be <NUM> degrees, and the third angle may be more than <NUM> degrees. The first plane may be greater than <NUM> degrees and smaller than <NUM> degrees relative to the second plane. The proximal section may include a first screw hole configured to direct a bone screw toward a femoral head when implanted within a femur. The bone screw hole may define a screw hole axis lying in the second plane. The distal section may include a second screw hole extending therethrough and defining screw hole axis lying in the second plane.

In a further aspect of the present disclosure, a femoral nail includes a proximal section, a distal section remote from the proximal section, and an intermediate section disposed between the proximal section and distal section. The intermediate section includes first and second curved portions. The first curved portion is positioned closer to the proximal section than the second curved portion. The second curved portion is curved in a first plane, and the first curved portion is curved in the first plane and a second and third plane.

Additionally, the second curved portion may be curved in the first plane and only in the first plane. The distal section may extend from the second curved portion and terminate at a distal tip. Also, the first and second planes may be oriented relative to each other at an obtuse angle, and the third plane may be disposed between the first and second planes and may be oriented relative to the first plane at an acute angle.

In an even further aspect of the present disclosure, a femoral nail includes a first section having a first screw hole extending through a sidewall thereof and defining a screw hole axis configured to extend toward a femoral head when the femoral nail is implanted within a femur. The screw hole axis lies in a first plane, and a second section extends from the first section and has first and second curved portions. The first curved portion is positioned closer to the first section than the second curved portion. The first curved portion is curved in the first plane and a second and third plane. The first curved portion has a proximal-distal length greater than that of the first curved portion.

Additionally, the second curved portion may terminate at a distal tip of the femoral nail. The nail may also include a distal section extending from the second curved portion. The second curved portion may be curved in the second plane. The first and second planes may be oriented relative to each other at an obtuse angle, and the third plane may be disposed between the first and second planes and may be oriented relative to the second plane at an acute angle.

The features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings in which:.

When referring to specific directions in the following discussion of certain implantable devices, it should be understood that such directions are described with regard to the implantable device's orientation and position during exemplary application to the human body. Thus, as used herein, the term "proximal" means close to the heart and the term "distal" means more distant from the heart. The term "inferior" means toward the feet and the term "superior" means toward the head. The term "anterior" means toward the front of the body or the face and the term "posterior" means toward the back of the body. The term "medial" means toward the midline of the body and the term "lateral" means away from the midline of the body. Also, as used herein, the terms "about," "generally" and "substantially" are intended to mean that slight deviations from absolute are included within the scope of the term so modified.

<FIG> depicts an exemplary left leg femur. The femur has a proximal femur <NUM>, distal femur <NUM>, and femoral shaft <NUM> that extends between the proximal and distal femurs <NUM>, <NUM>. Proximal femur <NUM> includes a greater trochanter <NUM> and femoral head <NUM>. As can be seen in <FIG>, femoral shaft <NUM> has an anterior bow such that the femur curves anteriorly in an anteroposterior extending plane. However, such curvature does not extend into proximal femur <NUM> which results in a slight posterior curvature or transitional bend <NUM> where femoral shaft <NUM> and proximal femur join <NUM>.

<FIG> depicts an exemplary prior art femoral nail <NUM> implanted within a femur, such as the femur in <FIG>, in an antegrade manner. As shown, the construction of femoral nail <NUM> is such that it has a portion <NUM> that impinges on the anterior cortex of the femur at transitional bend <NUM> between femoral shaft <NUM> and proximal femur <NUM>. Such impingement may be caused by an underestimation of the curvature of the femur and, as illustrated in <FIG>, may occur at transitional bend <NUM> which is a location at or near the transition or necking down of the proximal femur <NUM> to the femoral shaft <NUM>. This can result in fracturing of the bone particularly as the nail <NUM> is impacted into the intramedullary canal of the femur. Moreover, even if fracture does not occur, the nail <NUM> may press against the cortex of the bone which can result in malalignment of both fracture fragments as well as the femoral nail <NUM> within the intramedullary canal as the nail may be constrained from coming to the desired seated position. This can lead to a non-anatomical bone shape when the bone fully heals, which can also lead to premature wear of articular cartilage in joint regions due to non-physiological alignments.

<FIG> depict a femoral nail <NUM> according to an embodiment of the present disclosure. Femoral nail <NUM> configured for implantation in a left leg and generally includes a proximal section <NUM>, a distal section <NUM> and an intermediate section therebetween. The intermediate section includes a first curved portion <NUM>, a straight portion <NUM>, and a second curved portion <NUM>.

In the particular embodiment depicted, proximal section <NUM> and distal section <NUM> are each substantially straight along their respective lengths. Distal section <NUM> terminates at a distal tip <NUM> which defines a distal end of nail <NUM>. Proximal section <NUM> is generally cylindrical and defines a longitudinal axis LA1 that extends along its length. Proximal section <NUM> defines a proximal end <NUM> of nail <NUM> which is configured to be coupled to an alignment/aiming instrument, such as by a threaded connection. An example of an aiming instrument is disclosed in <CIT>. Also, as best shown in <FIG>, proximal end <NUM> includes a plurality of notches 16a-c positioned at predetermined intervals about the longitudinal axis LA1 of proximal section <NUM>. Such notches 16a-c collectively form a clocking feature that helps properly orient femoral nail <NUM> respective to a femur during implantation and may assist in the connection between the alignment/aiming instrument and femoral nail <NUM>.

Femoral nail <NUM> also includes a plurality of screw holes <NUM>, <NUM>, <NUM>, <NUM>. <NUM>, <NUM> extending therethrough. As best shown in <FIG>, nail <NUM> includes a first set of screw holes extending through proximal section <NUM> and the intermediate section, and a second set of screw holes extending through distal section <NUM>. The first set of screw holes includes recon screw holes <NUM>, a compression screw hole <NUM>, and a static screw hole <NUM>. Compression screw hole <NUM> is an elongate screw hole that defines an axis extending perpendicular to axis LA1 and allows for screw movement along axis LA1. Static screw hole <NUM> extends through intermediate section near proximal section <NUM> and also defines a screw hole axis that is perpendicular to axis LA1. However, static screw hole <NUM> constrains any screw inserted therein from movement along axis LA1.

The recon screw holes <NUM> form three openings 30a, 30b, and 30c at one side (i.e., lateral side) of nail and two openings 30b and 30a,c at an opposite side (i.e., medial side) of nail. In this regard, openings 30a and 30c converge to single opening 30a,c. Thus, a screw inserted through opening 30a or 30c extends through opening 30a,c at the opposite side of nail <NUM>, while a screw inserted through opening 30b at one side of nail <NUM> extends through opening 30b at the opposite side of nail <NUM>. As shown in <FIG>, the screw holes <NUM> that are defined by openings 30a, 30b, and 30a,c define axes that extend at an oblique angle relative to axis LA1 and lie in a plane extending in a direction B as indicated by the arrow B in the figure. Such plane is referred to herein as a second plane or reconstruction plane ("Recon Plane"). The axes defined by openings 30a, 30b, and 30a,c also extend toward a femoral head and femoral neck of a patient's femur when implanted therein for a recon mode of fixation. Screw holes <NUM>, <NUM>, and <NUM> provide for multiple modes of fixation, such as the recon mode of fixation just mentioned as well as several others not specifically described herein.

The second set of screw holes, which extend through the distal section of nail, include static screw holes <NUM>, a compression screw hole <NUM>, and a transverse screw hole <NUM>. Static screw holes <NUM> and compression screw hole <NUM> each extend through distal section <NUM> and define screw hole axes that are perpendicular to a longitudinal axis of distal section <NUM> and lie within the Recon Plane, as best shown in <FIG>. Transverse screw hole <NUM> extends through distal portion <NUM> transverse to screw holes 40a-b and <NUM> and has an axis that is perpendicular to the longitudinal axis of distal section and lies within a plane which itself extends in a direction A, as shown in <FIG>. Such plane is referred to herein as a first plane or radius of center plane ("ROC Plane"), as is described in more detail below. Also, transverse screw hole <NUM> is situated between static screw holes <NUM> along with compression screw hole <NUM>.

In addition to the screw holes mentioned above, a bore <NUM> extends through proximal end <NUM> of nail <NUM> along its length and through distal tip <NUM>. Proximal section <NUM> is internally threaded along a portion of the length of bore <NUM> adjacent the proximal end <NUM>. Such internal threading is configured to mate with an alignment/aiming instrument and setscrew or cap, for example.

As mentioned above, the intermediate section includes a first curved or bent portion <NUM>, a second curved or bent portion <NUM>, and a straight portion <NUM>. As depicted, first curved portion <NUM> extends distally from proximal section <NUM>, second curved portion <NUM> extends proximally from distal section <NUM>, and straight portion <NUM> is positioned between first and second curved portions <NUM>, <NUM>. Second curved portion <NUM> has a radius of curvature R2 of about <NUM> to <NUM> which has been determined to conform to the anterior femoral bow of <NUM>% of the patient population based on a diversified population analysis using a central database that contains geometric data of human bones. Second curved portion <NUM> is curved or bent in the first plane that extends in a direction A (indicated by arrow A in <FIG>). Hence, the first plane is referred to as the ROC Plane as mentioned above. In the particular embodiment depicted, second curved portion <NUM> is curved/bent in only the ROC Plane. However, it is contemplated that second curved portion <NUM> may be curved/bent in other planes transverse to the ROC Plane as desired to match a patient(s) anatomy.

Straight portion <NUM> is positioned between first and second curved portions <NUM>, <NUM> and tapers from first curved portion <NUM> toward second curved portion <NUM> as this portion of nail <NUM> is intended to reside in the transition region between the metaphysis and diaphysis of the proximal femur. Straight portion <NUM> also defines a longitudinal axis LA2 extending along its length.

First curved portion <NUM> is shorter in length than second curved portion <NUM> and has a first radius of curvature R1 of about <NUM> to <NUM> as depicted in <FIG>. In addition, first curved portion <NUM> is curved/bent in three separate, intersecting planes. More specifically, first curved portion <NUM> is curved/bent in the first plane or ROC Plane, as shown in <FIG>. First curved portion <NUM> is also curved/bent in a second plane or Recon plane that extends in a direction B, as depicted in <FIG>. Moreover, first curved portion <NUM> is curved/bent in a third plane that extends in a direction C, as best shown in <FIG>. The bends/curves in each of these planes define a radius of curvature of the first curved portion <NUM>. Radius of curvature R1, which is mentioned above, lies in the third plane.

The bends of first curved portion <NUM> in each of the first, second, and third planes has the effect of orienting longitudinal axis LA2 of straight portion <NUM> relative to longitudinal axis LA1 of proximal section <NUM> at first, second, and third angles <NUM>, <NUM>, and <NUM> within those respective planes. In other words, due to the multi-planar curvature of first curved portion <NUM>, axis LA2 is angled relative to axis LA1 in the ROC Plane by a first bend angle θ1, in the Recon Plane by as second bend angle <NUM>, and in a Resultant Bend Plane by a third bend angle <NUM>, as shows in <FIG>, <FIG>, respectively. Moreover, in the embodiment depicted, bend angles <NUM>, <NUM>, and <NUM> differ in magnitude. However, it is contemplated that bend angles <NUM>, <NUM>, and θ3 may be equal in each of the three planes. Where bend angles differ, third bend angle θ3 is a resultant of the first and second bend angles θ1 and <NUM>. In this regard, the magnitude of θ3 and the orientation of the Resultant Bend Plane relative to the other planes are a function of θ1 and θ2 and the angular orientation between the ROC Plane and Recon Plane in which such first and second bends respectively lie. As an example, in the depicted embodiment, first bend angle θ1 is preferably <NUM> degrees in the ROC Plane, and second bend angle θ2 is preferably <NUM> degrees in the Recon Plane where the ROC Plane and Recon Planes are oriented at an oblique angle α which is preferably <NUM> degrees, as best shown in <FIG>. Thus, in this example, third bend angle is about <NUM> degrees and Resultant Bend Plane is oriented about <NUM> degrees relative to ROC Plane and <NUM> degrees relative to Recon Plane.

It should be understood that while bend <NUM>, <NUM>, and θ3 are preferably and respectively <NUM>, <NUM>, and <NUM> degrees and angle α is preferably <NUM> degrees, these angles may differ. As such, angle α may be between <NUM> and <NUM> degrees, first bend angle θ1 may be between <NUM> and <NUM> degrees, second bend angle θ2 may be between <NUM> and <NUM> degrees, and third bend angle θ3 may be between <NUM> and <NUM> degrees. Such angles have been determined to suitably fit <NUM>% of the patient population without the femoral cortex impingement described above based on a database analysis of a diverse population of bones.

<FIG> schematically illustrates the above described multi-planar bends/curves of first curved portion to help visualize the bends and how such bends are related to other structural features of nail <NUM>, such as proximal notches 16a-c. As shown, first curved portion <NUM> bends in the ROC Plane at bend angle θ1 from axis LA2 of straight portion <NUM>. First curved portion <NUM> also bends in the Recon Plane from axis LA2 at bend angle θ2. This results in axis LA1 of proximal section <NUM> being angled relative to axis LA2 of straight section by an angle θ3 in the Resultant Bend Plane. Also, as can be seen, a Cartesian coordinate system is established such that the z-axis extends generally in an anterior-posterior direction, the x-axis extends generally in a lateral-medial direction, and the y-axis extends generally in a superior-inferior direction with the origin being located at the interface between first curved portion <NUM> and straight portion <NUM>. The origin may also be located anywhere from about <NUM>% to <NUM>% of the length of nail <NUM> measured from a proximal end thereof. The y-axis coincides with longitudinal axis LA2 of straight section <NUM> and also defines the intersection between the ROC Plane, Recon Plane, and Resultant Bend Plane. Thus, for the left legged nail <NUM> described herein, the multi-planar bend has the effect of orienting proximal section <NUM> anteriorly and medially relative to straight portion <NUM>. In this regard, proximal section <NUM> slopes posteriorly in the superior to inferior direction which results in a canting away of nail <NUM> from an anterior cortex of a femur at the common impingement area as illustrated in <FIG>. It also aligns proximal section <NUM> and intermediate section with the natural lateral-medial curve of a femur. It should be understood that these bends are mirrored for a right-legged femoral nail.

As also shown in <FIG>, ROC Plane is oriented relative to the Recon Plane in the Cartesian coordinate system by the obtuse angle α. Thus, the Recon Plane is oriented relative to the x-plane within the Cartesian coordinate system by α-<NUM>°. Thus, where angle α is <NUM> degrees, Recon Plane is angled relative to the x-plane by <NUM> degrees. This offset of the Recon Plane relative to the x-plane helps form the bend in the Resultant Bend Plane and happens to also be equal to the angle ψ1. ψ1 is the angle formed between the ROC Plane and a longitudinal axis LA3 which bisects notches 16a and 16c, as shown in <FIG>. In addition, an angle ψ2 is formed between axis LA3 and Resultant Bend Plane. Thus, the angle between the ROC Plane and the Resultant Bend plane is equal to the sum of ψ1 and ψ2. Therefore, in the example provided above where α is <NUM> degrees, ψ1 is <NUM> degrees, and ψ2 is <NUM> degrees, the angle between the ROC Plane and Resultant Bend Plane is <NUM> degrees.

<FIG> illustrates the above described effect on femoral cortex impingement of the multi-planar bends. As shown, nail <NUM> overlays prior art nail <NUM> and, as a result of bends of first curve portion <NUM>, nail <NUM> cants away from the anterior cortex of the femur at the common impingement zone of prior art nail <NUM> thereby reducing the possibility of femoral cortex impingement.

Femoral nail <NUM> may have alternative constructions to that described above while remaining within the scope of the invention. For example, in one embodiment, femoral nail <NUM> may not include a straight distal end <NUM>. Instead, second curved portion <NUM> may define the distal end <NUM> of nail <NUM>. In this regard, second curved portion <NUM> may curve about its center of curvature from straight portion <NUM> all the way to distal tip <NUM> of femoral nail <NUM>. Alternatively, distal section <NUM> may itself be curved/bent in one or more planes so that it has a different radius of curvature than that of second curved portion <NUM>. In addition, proximal section <NUM> may also be curved/bent along its length in one or more planes.

In another example which does not fall within the scope of the claims, nail <NUM> may not include a straight portion <NUM> within the intermediate section. In such embodiment, second curved portion <NUM> may then be positioned adjacent first curved portion <NUM> and may extend distally therefrom. Thus, intermediate section may include a first curved portion <NUM> with a first radius of curvature R1 that defines bends in three separate planes, and a second curved portion <NUM> extending distally from the first curved portion <NUM> and curved/bent about a center of curvature in at least one plane. Although, in this example, the straight portion <NUM> may be absent, the advantages described above with regard to nail <NUM> may still be present.

Moreover, it should be understood that while it is described herein that first curved portion <NUM> and second curved portion <NUM> are each curved/bent in the ROC Plane, this may not be the case in every embodiment. It is possible that first curved portion <NUM> may be curved bent in three separate planes where none of these planes are coincident with the plane in which second curved portion <NUM> is curved.

Claim 1:
A femoral nail (<NUM>) comprising:
a proximal portion (<NUM>) configured to engage a driving tool for driving the femoral nail (<NUM>) into a femur;
a distal portion (<NUM>) remote from the proximal portion (<NUM>); and
an intermediate portion disposed between the proximal portion (<NUM>) and distal portion (<NUM>), the intermediate portion having a first bent section (<NUM>) that is bent in three-dimensions such that a first bend of the first bent section (<NUM>) is in a first plane, a second bend is in a second plane, and a third bend is in a third plane, the first and second planes intersecting at an oblique angle relative to each other, the third bend defining a non-zero radius of curvature in the third plane of the first bent section (<NUM>), the intermediate portion having a straight portion (<NUM>), wherein the first bent section (<NUM>) is disposed between the straight portion (<NUM>) and the proximal portion (<NUM>),
the straight portion (<NUM>) defines a longitudinal axis (LA2) extending along its length,
the proximal portion (<NUM>) defines a longitudinal axis (LA1) thatextends along its length,
wherein the first bent section (<NUM>) is bent such that a longitudinal axis (LA2) of the sraight portion (<NUM>) is oriented relative to a longitudinal axis (LA1) of the proximal portion (<NUM>) by a third bend angle (θ3) in the third plane,
wherein the third bend angle (θ3) is between <NUM> and <NUM> degrees.