FIELD

The present disclosure relates generally to bone tunnels and, more specifically, to a bone dilator apparatus for creating tunnels in bone.

BACKGROUND

Bone tunnel dilators are used to prepare a tunnel drilled within a bone in which the tunnel is adapted to receive a graft, such as in the repair of an anterior cruciate ligament (ACL) or other surgical procedure involving securing a graft in a bone. When using a dilator, after the bone tunnel is drilled, the dilator is inserted into an end of the tunnel and is driven into the tunnel to dilate an end of the tunnel to a shape configured to receive the graft selected for the particular procedure. In addition to dilating and reshaping the drilled hole, the dilating process also compacts the cancellous bone to provide a more dense structure into which the graft may become integrated.

In a bone tunnel dilator, the dilating element typically is formed on the leading end of a rigid shaft and is driven, in increments, into the tunnel end by repeatedly impacting the trailing end of the shaft, as with a hammer. Alternatively, slap hammers have been developed and are widely used in orthopedic procedures to apply an impacting force on various tools used during surgery. Slap hammers typically consist of a guide rod and a sliding weight. One end of the guide rod is affixed to a surface or an object, such as a dilator. The sliding weight may be thrown upward, generating a jerking force when the sliding weight strikes a stop on the end of the guide rod. The sliding weight may be repeatedly "thrown" to pull, rather than push, the dilating element into the tunnel end.

During ACL reconstruction, tunnel creation is traditionally done by drilling into the femur and tibia, creating circular tunnels. Specifically with regard to the femur, the tunnel is either drilled from the exterior cortex of the femur into the knee joint (an "outside-in" procedure) or drilled from the inside of the knee joint at the femoral ACL footprint (an "inside-out" procedure) to a certain depth which creates a socket for the graft to fit into. However, in the case of a rectangular bone graft, a circular tunnel does not provide the best fit to facilitate bone growth. The same holds true for circular tunnels drilled into the tibia. BRIEF SUMMARY

The present disclosure is directed towards a method and an apparatus for creating rectangular tunnels in the femur by using a rectangular dilator. The dilator uses a slap hammer in an inside-out approach to create a rectangular tunnel beginning in the knee joint at the femoral ACL footprint to a depth dependent on the bone graft length. A similar method could be used for tibial tunnel creation.

Further examples of the method and apparatus of this disclosure may include one or more of the following, in any suitable combination.

Examples of the bone dilator apparatus of this disclosure include an elongate, tubular member having a proximal end, a distal end, and an internal cannulation extending

therebetween. The distal end of the tubular member is adapted to form a round tunnel in bone. The apparatus also includes a flexible member having a proximal end and a distal end. A dilating element is disposed at the distal end of the flexible member. The flexible member is sized to be slidably received with the cannulation of the tubular member such that the dilating element extends from the distal end of the tubular member. The dilating element is adapted to be pulled into an end of the bone tunnel by applying a pulling force to the proximal end of the tubular member to dilate the end of the bone tunnel to a shape and size defined by the dilating element.

In further examples of the apparatus, the pulling force is created by a slap hammer assembly, which is configured for reciprocal motion. The tubular member has threads for forming the round tunnel in bone. A diameter of the tubular member is about 5 mm. The proximal end of the flexible member includes a hook for attachment to a pulling device. The dilating element has a proximal conical section, a tubular mid-section, and a distal, substantially rectangular section. A cross-section of the substantially rectangular section is larger than a cross-section of the tubular mid-section.

In yet further examples, the dilating element includes a plurality of ridges spaced axially along a portion of the dilating element. A length of the flexible member is selected to be larger than a length of the tubular member. In examples, a length of the flexible member is about 8 inches and a length of the tubular member is about 6.75 inches. The shape of the dilated end of the bone tunnel is substantially rectangular. A largest height of the dilating element is about 9.65 mm and a largest width of the dilator element is about 5.08 mm. Examples of the method of dilating a bone tunnel of this disclosure include: 1) drilling a round tunnel from a surface of bone into a joint space using a distal end of a tubular member such that a proximal end of the tubular member extends from the surface of bone and the distal end of the tubular member is located at an end of the tunnel at the joint space; 2) passing a flexible member having a dilator element through a cannulation of the tubular member such that the dilator element extends into the joint space, the dilator element having a substantially rectangular cross-section; 3) attaching a slap hammer assembly to the proximal end of the tubular member; and 4) creating a pulling force using the slap hammer assembly, the pulling force causing the dilator element to enter the end of the tunnel at the joint space and form a rectangular dilated tunnel from the joint space to a pre-determined depth in bone.

In further examples, the method includes drilling a guide wire from the surface of bone into the joint space. Passing the flexible member though the cannulation of the tubular member includes attaching a hooked end of the flexible member to a pulling element, the pulling element pulling the flexible member into the cannulation. In examples, a diameter of the round tunnel is about 5 mm. A height of the rectangular dilated tunnel is about 9.65 mm and a width of the rectangular dilated tunnel is about 5.08 mm. The bone may be a human femur.

These and other features and advantages will be apparent from a reading of the following detailed description and a review of the associated drawings. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of aspects as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be more fully understood by reference to the detailed description, in conjunction with the following figures, wherein:

FIG. 1 A is a perspective, partially assembled view of an exemplary bone dilator apparatus of this disclosure;

FIG. IB is a side view of the drill adaptor of FIG. 1A;

FIGS. 1C and ID are detailed views of the mating regions of the drill adaptor and slap hammer assembly of FIG. 1 A;

FIG. IE is a side view of the slap hammer assembly of FIG. 1 A; FIG. 2A is a side view of the wire shaft of FIG. 1 A;

FIGS. 2B and 2C are detailed views of the hook and dilator element, respectively, of the wire shaft of FIG. 2 A;

FIG. 2D is bottom view of the rectangular portion of the dilator element of FIG. 2C; FIGS. 3A and 3B are an alternative example of the bone dilator apparatus of FIGS. 1A and IE; and

FIGS. 4A-D illustrate a method of drilling and dilating a bone tunnel using the bone dilator apparatus of FIG. 3 A. DETAILED DESCRIPTION

In the description that follows, like components have been given the same reference numerals, regardless of whether they are shown in different examples. To illustrate example(s) in a clear and concise manner, the drawings may not necessarily be to scale and certain features may be shown in somewhat schematic form. Features that are described and/or illustrated with respect to one example may be used in the same way or in a similar way in one or more other examples and/or in combination with or instead of the features of the other examples.

As used in the specification and claims, for the purposes of describing and defining the invention, the terms "about" and "substantially" are used represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms "about" and "substantially" are also used herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. "Comprise,"

"include," and/or plural forms of each are open ended and include the listed parts and can include additional parts that are not listed. "And/or" is open-ended and includes one or more of the listed parts and combinations of the listed parts.

FIG. 1 A illustrates an exemplary bone dilator apparatus 10 in a partially-assembled, perspective view. The bone dilator apparatus 10 is shown as extending from a proximal end (P) to a distal end (D). The component parts of dilator apparatus 10 may be fabricated from light, strong and rigid biocompatible materials. For example, the components may comprise metal, metal alloys, polymeric composites or other known suitable materials. In some examples, various components or the entire dilator apparatus 10 may be disassembled or taken apart for storage and/or cleaning. It should be understood that although the illustrative examples describe reshaping the bone hole to a rectangular cross-section, the disclosure may also be used to dilate bone tunnels to other geometric configurations.

In FIG. 1A, the dilator apparatus 10 includes an elongate, cylindrical drill adapter 12 having an interior cannulation 11 for receiving a flexible wire shaft 14 therethrough. A diameter of the drill adaptor may be about 5 mm. A dilator element 16, shown in more detail in FIG. 2C, is located at the distal-most end of the wire shaft 14. The wire shaft 14 and dilator element 16 may be formed as an integral, single unit and may be made from a single mass of material such as surgical stainless steel or other suitable metal, or a polymer of sufficient hardness to perform dilating and smoothing functions. Alternately, the wire shaft 14 and the dilator element 16 may be made from components attached to each other to form the complete device. A length of the wire shaft 14 is selected to extend completely through the cannulation

11 of the drill adaptor 12. For example, a length of the wire shaft may be about 8.0 inches and a length of the drill adaptor may be about 6.75 inches. A proximal end of the drill adaptor

12 is adapted to axially couple with a surgical slap hammer assembly 20, as further described below.

Still referring to FIG. 1 A, the slap hammer assembly 20 generally comprises a slap hammer adaptor 18, a striking member 22, and a sliding weight 24. The slap hammer adaptor 18 also has an opening 27 for receiving mating with the drill adaptor 12. A diameter of the slap hammer adaptor 18 may be about 0.4 inches. The striking member 22, which may have a circular cross-section, is located at or near the proximal-most end of the slap hammer adaptor 18. The striking member 20 may be fixedly attached to the proximal end of the slap hammer adaptor 18. However, it is contemplated by this disclosure that the striking member 20 may be configured to slide axially along the slap hammer adaptor 18 and locked into place at a selected point along the slap hammer adaptor 18 in order to control the force delivered by the striking member 24. Various slap hammer assemblies 20 may be configured in many different dimensions, and deliver a wide range of impact forces. In some examples, the slap hammer assembly 20 may be dimensioned for delivering substantially large impact forces, and in other examples the slap hammer assembly 20 may be dimensioned for delivering lesser impact forces. FIG. IB shows a side view of the drill adaptor 12. The drill adaptor 12 includes a distal dilator end 28 for drilling the initial, circular tunnel and for connecting to the dilator element 16. A surface of the drill adaptor 12 may further include laser markings (not shown) to indicate insertion depth. The drill adaptor 12 also comprises a proximal, slap hammer end 26 which is adapted for connecting to the slap hammer adaptor 18. For example, as shown in FIG. 1C, the slap hammer end 26 of the drill adaptor 12 may comprise an area of reduced diameter 25 that forms an interference fit with the opening 27 at the distal end of the slap hammer adaptor 18. Alternatively, as shown in FIG. ID, the slap hammer end 26 of the drill adaptor 12 may comprise threads 29 for mating with corresponding threads 31 in the opening 27 of the slap hammer adaptor 18.

FIG. IE shows a side view of the slap hammer assembly 20, including the striking member 22, the sliding weight 24, and the slap hammer adaptor 18. A diameter of the striking member 22 is selected to be larger than the diameter of the slap hammer adaptor 18. The sliding weight 24 has a generally cylindrical shape and is adapted to axially slide over the slap hammer adaptor 18, as further described below. A diameter of the sliding weight 24 is selected to be larger than the diameter of the striking member 22. A size, shape, and surface texture of the sliding weight 24 may all be configured for easy grip by the hand of a user.

The wire shaft 14 is shown in more detail in FIGS. 2A-C. In FIG. 2 A, the wire shaft 14 includes a hook 30 at the proximal-most end opposite the dilator element 16. The hook 30 (FIG. 2B) is configured to connect to a pulling device, such as a suture retriever (not shown), to pull the wire shaft 14 into place, as further described below. A largest dimension of the hook 30 is selected to be smaller than a diameter of the cannulation 11 of the drill adaptor 12 (FIG. 1 A), so that the hook 30 may pass through the cannulation 11 of the drill adaptor 12 when pulled by the pulling device.

Examples of the dilator element 16, shown in FIG. 2C, include a conical section 32 and a threaded, cylindrical, mid-section 34 configured for threaded engagement within the drill adaptor 12. The mid-section 34 may additionally comprise other features, such as equidistant flat edges (not shown), to allow for ease of connection. A rectangular section 36, in the illustrative example, is approximately rectangular in cross-section. However, it is contemplated by this disclosure that the rectangular section 36 has radiused corners so that a cross-section may be considered as slightly oval. A transition region 38 is formed at the proximal end of the rectangular section 36 of the dilator element 16 to progressively expand the cross-sectional dimensions of the dilator element 16 from a circular shape to a larger, rectangular shape.

Still referring to FIG. 2C, the dilator element 16 further includes a first through hole 40 for the passage of a suture (such as a #2 leading suture) and a second through hole 42 for receiving a set screw or suitable element (not shown) to secure the dilator element 16 to the wire shaft 14. The rectangular section 36 of the dilator element 16 is further formed to define a number of axially spaced ridges 44 circumscribing its outer surface, the ridges 44 extending approximately along directions transverse to the longitudinal axis of the dilator element 16. The ridges 44 dilate and cut the side walls of the bone tunnel as the dilator element 16 is first advanced to define a dilated sidewall and then is retracted to smoothen the sidewall surface to more closely accommodate a bone graft.

In examples, a largest height (H) of the rectangular section 36 of the dilator element 16 may be about 9.65 mm. A bottom view of the rectangular section 36 of the dilator element 16 is shown in FIG. 2D. In FIG. 2D, a width (W) of the rectangular section 36 may be about 5.08 mm. The height (H) and the width (W) of the rectangular section 36 corresponds to the height and width of the rectangular bone tunnel formed by the dilator element 16.

An alternative example of the bone dilator apparatus 10' is shown in FIGS. 3A and 3B. The bone dilator apparatus 10' shown in FIGS. 3A and 3B is substantially the same as the bone dilator apparatus 10 of FIGS. 1 A and IE except that the bone dilator apparatus 10' includes a stop element 46 located at or near the distal-most end of the drill adaptor 18 for reciprocating motion of the sliding weight 24. In this example, the slap hammer end 26 of the drill adaptor 12 is adapted for connecting to the stop element 46.

Methods of using the dilator apparatus 10' are illustrated in FIGS. 4A-D. As stated above, the dilator apparatus 10' generally serves to enlarge and change a cross-sectional shape of a bone hole or tunnel from a circular cross-section to a rectangular cross-section that is better adapted to receive a rectangular bone graft. In examples, the bone graft may be attached to soft tissue, such as a replacement ACL. However, the dilator apparatus 10' of the present disclosure may be usable in other orthopedic applications.

In FIG. 4A, a surgeon first drills a small pilot hole 50 through a bone 52 (e.g. a femur), starting at the exterior cortex 53 and into the joint space 54, using, for example, a 2.4 mm guide wire. As shown in FIG. 4B, the surgeon then over drills, from the same starting point, a larger, coaxial, round hole 56 using the drill adaptor 12. In FIG. 4B, the round hole 56 extends the entire length of the pilot hole 50.

As shown in FIG. 4C, with the drill adaptor 12 still in place in the round hole 56 and extending out of the round hole 56, a pulling device 58 is fed into the drill adaptor 12 from the slap hammer end 26 to the dilator end 28. The pulling device 58 is further extended through the dilator end 28 into the joint space 54. From inside the joint space 54, the pulling device 58 is looped around the hook 30 of the wire shaft 14 and the wire shaft 14 is pulled inside the drill adaptor 12 until the dilator element 16 extends from the dilator end 28 into the joint space 54 and the hook 30 of the wire shaft 14 extends from the slap hammer end 26. At this point, the hook 30 and a portion of the wire shaft 14 also extend out of the patient's body.

In FIG. 4D, the dilator element 16 is connected to the drill adaptor 12. Once connected, the dilator element 16 is then advanced towards the bone 52 until the transition region 38 reaches the entry of the round hole 56. The slap hammer adaptor 18 is attached to the drill adaptor 12. By repeatedly striking or hammering the sliding weight 24 against the striking member 22, transition region 38 of the dilator element 16 is pulled in the direction (D), in increments, into the round hole 56. By repetitive hammering, the transition portion 38 acts to change the round hole 56 to a rectangular shape. That is, during the hammering process, with each pull of the dilator element 16, the bone material deforms progressively into the shape of the rectangular section 36 of the dilator element 16 as the dilator element 16 is progressively forced deeper into the round hole 56. Dilation occurs until the appropriate length of rectangular bone hole 60 is reached. The resulting rectangular bone hole 60 can advantageously receive a rectangular bone graft (not shown) that results in a better fit to facilitate bone growth and incorporation of the graft into the native bone as compared to a round hole.

Once femoral rectangular dilation is completed, the slap hammer adaptor 18 can be disconnected from the drill adaptor 12. The dilator element 16 is removed after being disconnected from the drill adaptor 12. The drill adaptor 12 can then be removed from the round hole 56. The bone graft can be passed through a tibial tunnel (not shown) into the rectangular bone hole 60 and fixation of the graft on the femur can then be completed. While this disclosure has been particularly shown and described with references to preferred examples thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present application as defined by the appended claims. Such variations are intended to be covered by the scope of this present application. As such, the foregoing description of examples of the present application is not intended to be limiting. Rather, any limitations to the disclosure are presented in the following claims.