WO2021154517A1

WO2021154517A1 - Graft fixation devices

Info

Publication number: WO2021154517A1
Application number: PCT/US2021/013640
Authority: WO
Inventors: Chun Liu; Ali HOSSEINI; Christopher D. MACCREADY
Original assignee: Smith & Nephew, Inc.; Smith & Nephew Orthopaedics Ag; Smith & Nephew Asia Pacific Pte. Limited
Priority date: 2020-01-27
Filing date: 2021-01-15
Publication date: 2021-08-05

Abstract

Graft fixation devices include a screw member and an anchor member assembled to an adjustable loop of suture for attachment to a tissue graft. The screw member has a threaded outer diameter to engage with cancellous bone as it is advanced through the tibia. The screw member has a first inner diameter with a circular shape to act as a counterbore to the anchor member, and a second inner diameter with a hexagon shape to mate with a delivery device. The anchor member is configured to pass through the hexagonal diameter of the screw member and rotate to be secured within the counterbore.

Description

GRAFT FIXATION DEVICES

FIELD

The present disclosure relates to graft fixation devices and, more particularly, to graft fixation devices for anterior cruciate ligament reconstruction.

BACKGROUND

A ligament, such as an anterior cruciate ligament (ACL), that has ruptured and is non- repairable, is generally replaced arthroscopically by a tissue graft. In some cases, the tissue graft can be harvested from a portion of a patellar tendon having so-called “bone blocks” at each end. Alternatively, the tissue graft can be formed from synthetic materials, or from a combination of synthetic and natural materials. The replacement tissue graft is usually implanted by securing one end of the tissue graft in a passage formed within the femur, and passing the other end of the graft through a passage formed in the tibia. Generally, sutures are used to affix each end of the tissue graft to a fastener which is secured either to the cortex of the bone (known as “suspensory fixation”) or within the cancellous layer of the bone (known as “interference fixation”).

Typically, surgeons can use either suspensory or interference fixation to attach the tissue graft to the femur. However, due to the lack of superficial tissue on the surface of the tibia, surgeons generally prefer to use sub-cortical fixation devices on the tibia to prevent patient discomfort caused by an implanted object under the small amount of tissue that protrudes past the bone. Nevertheless, in some cases, use of suspensory fixation on the tibia is either preferred or unavoidable. For example, all-inside ACL reconstructions require the use of suspensory fixation in both the femur and the tibia. In such cases, the fastener on the tibia is easily visible and/or palpable post-operation, making it cosmetically inferior to interference fixation. It is therefore desirable to have a method of suspensory fixation on the tibia which avoids the issue of cosmesis post-operation.

SUMMARY

Described herein is a graft fixation device which can be used to provide suspensory fixation on the tibia during an ACL reconstruction. The fixation device includes a screw member and an anchor member which is factory assembled to an adjustable loop of suture for attachment to a tissue graft. The screw member has a threaded outer diameter to engage with cancellous bone as it is advanced through the tibia. The screw member has two uniquely sized inner diameters. The first inner diameter has a circular shape to act as a counterbore to the anchor member, and the second inner diameter has a hexagon shape to mate with a delivery device. The anchor member of the fixation device is configured to pass through the hexagonal diameter of the screw member and rotate to be secured within the counterbore. Advantageously, the graft fixation device of this disclosure provides a means of fixating tendon to bone using suspensory fixation where the implanted suspensory device sits beneath the cortical layer of bone, thus avoiding the issue of cosmesis post-operation.

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

In examples, fixation devices of this disclosure include a first body having a proximal end, a distal end and a cannulation extending along a longitudinal axis between the proximal and distal ends. A proximal end of the cannulation has a first inner diameter, and a distal end of the cannulation has a second inner diameter. A length of the second body is selected to be slightly larger than the first inner diameter of the first body, and a width of the second body selected to be smaller than the second inner diameter of the first body. The second body is configured to be inserted through the second inner diameter of the first body along the longitudinal axis and rotated to be secured within the first inner diameter transverse to the longitudinal axis.

In further examples, the first inner diameter of the cannulation of the first body is selected to be larger than the second inner diameter of the cannulation of the first body. In examples, an outer surface of the first body has a helical thread for allowing the first body to be screwed into bone. In examples, the first inner diameter has a circular shape and the second inner diameter has a hexagon shape. In examples, the second inner diameter is configured to mate with a shaft of a delivery device passed through the first inner diameter.

In examples, the first inner diameter is about 7.6 mm and the second inner diameter is about 4.5 mm. In examples, the second body defines a plurality of through holes configured for attachment to an adjustable suture loop. In examples, at least one of the first body and the second body is made from a biocompatible material. Examples of a method of surgical repair of this disclosure include inserting a first body of a fixation device into a tunnel in bone. The first body has a proximal end, a distal end and a cannulation extending along a longitudinal axis between the proximal and distal ends.

A proximal end of the cannulation has a first inner diameter, and a distal end of the cannulation has a second inner diameter. A second body of the fixation device is passed through the second inner diameter of the first body along the longitudinal axis. The second body is then rotated to be secured within the first inner diameter transverse to the longitudinal axis.

In further examples, the first inner diameter of the cannulation of the first body is selected to be larger than the second inner diameter of the cannulation of the first body. In examples, the second body has a length and a width. The length of the second body is selected to be slightly larger than the first inner diameter of the first body, and the width of the second body is selected to be smaller than the second inner diameter of the first body. In examples, inserting the first body of the fixation device into the tunnel includes screwing the first body into the tunnel with a delivery device. In examples, screwing the first body into the tunnel with a delivery device includes passing a portion of the delivery device through the first inner diameter. In examples, the second body is attached to an adjustable suture loop through a plurality of through holes defined by the second body. In examples, the method further includes tensioning the adjustable suture loop by pulling on free ends of the adjustable suture loop. In examples, an outer surface of the first body has a helical thread for allowing the first body to be screwed into the bone. In examples, the first inner diameter has a circular shape and the second inner diameter has a hexagon shape.

These and other features and advantages is 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 is more fully understood by reference to the detailed description, in conjunction with the following figures, wherein:

FIG. 1 illustrates a prior art example of an ACL repair using a tissue graft; FIG. 2 illustrates an example of the assembled fixation device of this disclosure;

FIGS. 3A and 3B illustrate an example of a screw member of the fixation device of this disclosure;

FIG. 4A illustrates an example of an anchor member of the fixation device of this disclosure;

FIG. 4B illustrates the example of the anchor member of FIG. 4A attached to an adjustable suture loop; and

FIGS. 5A-C illustrate an example of the use of the fixation device of this disclosure.

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 to 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.

Referring now to FIG. 1, a prior art example of an ACL repair and reconstruction procedure is shown in a patient’s knee 10 having a femur 12, a tibia 13 and a joint space 11 in between. During the repair, one or more tissue grafts 18a, 18b are secured at openings 19a, 19b to femoral channels 14a, 14b within the femur 12 with anchor members 22a, 22b using suspensory fixation. The tissue grafts 18a, 18b are tensioned at opposing ends of the tibial channels 16a, 16b from the anchor members 22a, 22b and secured in place with screws or other types of bone anchors 20a, 20b using interference fixation. However, as stated above, it may be desirable for the surgeon to provide suspensory fixation of the tissue grafts 18a, 18b on the cortex 13a of the tibia 13.

Turning now to FIG. 2, an example of a fixation device 30 of this disclosure is shown in an assembled view. The fixation device 30 can be used, for example, in the repair of an ACL in a patient’s knee. However, it is contemplated by this disclosure that the fixation device 30 could also be scaled for use in other types of ligament repairs or procedures. The fixation device 30 generally comprises a screw member 32 and an anchor member 40 configured to be secured within the screw member 32. Each of the screw member 32 and the anchor member 40 can be made from a biocompatible metal, such as stainless steel or titanium. However, a biocompatible plastic, such as polyetheretherketone (PEEK), could also be used.

Turning now to FIGS. 3 A and 3B, examples of the screw member 32 of this disclosure are shown in a detailed view. In examples, the screw member 32 comprises a cylindrical screw body 34 having a proximal end 34a and a distal end 34b. An exterior of the screw body 34 may comprise a helical thread 36 to enable the screw body 34 to be screwed into a bone hole. In other examples, not shown, the exterior of the screw body 34 may comprise other features, such as ribs or barbs, which increase the pull-out resistance of the screw body 34 in a case where the screw body 34 is pounded into the bone hole. In other examples, not shown, the screw body 34 could be conical shaped, providing resistance against being pulled into the bone tunnel. Furthermore, with a conical screw body 34, a smaller diameter tunnel could be placed on tibial side, leading to less bone removal, higher mechanical resistance, and usability for an all-inside repair. The screw body 34 defines an interior cannulation 38 extending from the proximal end 34a to the distal end 34b of the screw body 34 along a longitudinal axis A. The cannulation 38 comprises a proximal portion 38a and a distal portion 38b. In examples, a diameter D¹ of the proximal portion 38a is selected to be larger than a diameter D² of the distal portion 38b. In examples, the diameter D¹ of the proximal portion 38a may be about 7.6mm while the diameter D² of the distal portion 38b may be about 4.5mm. The distal portion 38b of the cannulation 38 may be configured to mate with a shaft of a delivery device inserted through the proximal portion 38a for screwing the screw body 34 into bone. For example, a shape of the distal portion 38b may be polygonal (e.g., hexagonal as shown) or may comprise other features that allow the distal portion 38b to mate with the delivery device while providing the necessary torque to enable the screw body 34 to be screwed into bone.

The proximal portion 38a of the cannulation 38 may have a circular shape configured as a counterbore to secure the anchor member 40 of the fixation device 30 within the proximal portion 38a, as further described below.

The disclosure also contemplates other examples of the screw body 34, not shown.

For example, the proximal portion 38a could have a polygonal shape for mating with the delivery device, while the distal portion 38b has a round shape for better torque delivery. In other examples, the distal end 34b could include either a countersink or a concave surface feature for facilitating the insertion of the anchor body 40 into the diameter D² and preventing potential resistance.

Turning now to FIG. 4A, an example of the anchor member 40 of the fixation device 30 of this disclosure is shown in a detailed view. The anchor member 40 may comprise a substantially flat, anchor body 42 having a proximal end 42a and a distal end 42b. A width W of the anchor body 42 is selected to be smaller than the diameter D² of the distal portion 38b of the cannulation 38 of the screw body 34 so that the anchor body 42 can be passed through the distal portion 38b. A length L of the anchor body 42 is selected to be slightly larger than the diameter D¹ of the proximal portion 38a of the cannulation 38 of the screw body 34 so that the anchor body 42 can be secured within the proximal portion 38a by an interference fit. In examples, the length L of the anchor body 42 may be smaller than a length of a typical anchor used in suspensory fixation. For examples, a length L of the anchor body 42 may be about 6.4mm. The disclosure also contemplates that the dimensions of the screw body 34 and the anchor body 42 could be selected to secure the anchor body 42 within the proximal portion 38a with a loose (i.e., non-interference) fit.

Turning now to FIG. 4B, the anchor member 40 may be preassembled to an adjustable suture loop 50 for attachment to a tissue graft 18a. However, it is also contemplated that the anchor member 40 could be attached to the tissue graft 18a by a non-adjustable length of suture. The adjustable suture loop 50 may be made of any common surgical suture material, including, for example, high-strength polyethylene. The anchor body 42 may define a plurality of through holes (e.g., four through holes 44a,b,c,d, as shown) near a center of the anchor body 42. The through holes 44a,b,c,d may be configured for the passage of individual strands of the adjustable suture loop 50. The anchor body 42 may also define additional through holes (e.g., two through holes 44e,f as shown) adjacent the respective proximal and distal ends 42a, 42b of the anchor body 42. The through holes 44e,f may be configured for the passage of the free ends 50a, b of the adjustable suture loop 50 which are used to tension the adjustable suture loop 50. The through holes 44e,f may additionally be used for the passage of additional sutures, not shown, needed to pull and/or flip the anchor body 42 relative to the screw body 34. However, it is contemplated by this disclosure that other combinations and/or configurations of through holes may be used to attach the anchor body 42 to the adjustable suture loop 50.

Use of the fixation device 30 will now be described with reference to FIG. 1 and FIGS. 5A-C in an ACL reconstruction. In FIGS. 5A-C, the adjustable suture loop 50 and tissue graft 18 of FIG. 4B are removed from the anchor member 40 for ease of illustration.

As shown in FIG. 1, once the tunnels 14a and 16b have been drilled through each of the femur 12 and the tibia 13, the tissue graft 18a is secured within the femur 12 using suspensory fixation. As shown in FIG. 5 A, the surgeon then passes a delivery device (not shown) through the proximal portion 38a of the screw member 32 to mate with the distal portion 38b of the screw member 32 to drive the screw member 32 into the tunnel 16b. The surgeon drives the screw member 32 into the tunnel 16a from the outside of the tibia 13 until the screw member 32 is flush with, or sunken past, the cortical layer of bone 13a. In this position, the screw member 32 is placed within the tunnel 16b such that the proximal end 34a of the screw body 34 is toward the cortical layer 13a and the distal end 34b of the screw body 34 is toward the joint space 11. The surgeon then passes the anchor member 40 (which has been pre-attached to the tissue graft 18a via the adjustable suture loop 50) lengthwise through the tunnel 16a along the longitudinal axis A of the screw body 34 towards the cortical layer 13a. As shown in FIG. 5B, the anchor member 40 then passes through the distal portion 38b of the cannulation 38 of the screw member 32. As shown in FIG. 5C, once the anchor member 40 has completely passed through the distal portion 38b of the screw member 32, the anchor member 40 is flipped so that the anchor member 40 is secured by an interference fit within the proximal portion 38a of the screw member 32 transverse to the longitudinal axis A. After the anchor member 40 has been seated within the proximal portion 38a, the adjustable suture loop 50 (FIG. 4B) attached to the anchor member 40 can be tensioned by pulling on the free ends 50a, b of the adjustable suture loop 50 until the tissue graft 18a is tensioned as desired. A knot can then be tied with the free ends 50a, b of the adjustable suture loop 50 against an outer surface of the anchor member 40 to retain the tissue graft 18a at the desired tension.

One skilled in the art will realize the disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing examples are therefore to be considered in all respects illustrative rather than limiting of the disclosure described herein. Scope of the disclosure is thus indicated by the appended claims, rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A fixation device comprising: a first body having a proximal end, a distal end and a cannulation extending along a longitudinal axis between the proximal and distal ends, a proximal end of the cannulation having a first inner diameter, and a distal end of the cannulation having a second inner diameter; and a second body configured to be inserted through the second inner diameter of the first body along the longitudinal axis and rotated to be secured within the first inner diameter transverse to the longitudinal axis.

2. The fixation device of claim 1, wherein a length of the second body is selected to be slightly larger than the first inner diameter of the first body, and a width of the second body is selected to be smaller than the second inner diameter of the first body.

3. The fixation device of claim 1, wherein the first inner diameter of the cannulation of the first body is selected to be larger than the second inner diameter of the cannulation of the first body.

4. The fixation device of claim 1, wherein an outer surface of the first body comprises a helical thread for allowing the first body to be screwed into bone.

5. The fixation device of claim 1, wherein the first inner diameter has a circular shape and the second inner diameter has a hexagon shape.

6. The fixation device of claim 1, wherein the second inner diameter is configured to mate with a shaft of a delivery device passed through the first inner diameter.

7. The fixation device of claim 1, wherein the first inner diameter is about 7.6 mm.

8 The fixation device of claim 1, wherein the second inner diameter is about 4.5 mm.

9. The fixation device of claim 1, wherein the second body defines a plurality of through holes configured for attachment to an adjustable suture loop.

10. The fixation device of claim 1, wherein at least one of the first body and the second body comprise a biocompatible material.

11. A method of surgical repair comprising: inserting a first body of a fixation device into a tunnel in bone, the first body having a proximal end, a distal end and a cannulation extending along a longitudinal axis between the proximal and distal ends, a proximal end of the cannulation having a first inner diameter, and a distal end of the cannulation having a second inner diameter; passing a second body of the fixation device through the second inner diameter of the first body along the longitudinal axis; and rotating the second body to be secured within the first inner diameter transverse to the longitudinal axis.

12. The method of claim 11, wherein the first inner diameter of the cannulation of the first body is selected to be larger than the second inner diameter of the cannulation of the first body.

13. The method of claim 11, wherein a length of the second body is selected to be slightly larger than the first inner diameter of the first body, and a width of the second body is selected to be smaller than the second inner diameter of the first body.

14. The method of claim 11, wherein inserting the first body of the fixation device into the tunnel comprises screwing the first body into the tunnel with a delivery device.

15. The method of claim 14, wherein screwing the first body into the tunnel with a delivery device comprises passing a portion of the delivery device through the first inner diameter.

16. The method of claim 11, wherein the second body is attached to an adjustable suture loop through a plurality of through holes defined by the second body.

17. The method of claim 16, further comprising tensioning the adjustable suture loop by pulling on free ends of the adjustable suture loop.

18. The method of claim 11, wherein an outer surface of the first body comprises a helical thread for allowing the first body to be screwed into the bone.

19. The method of claim 11, wherein the first inner diameter has a circular shape.

20 The method of claim 11, wherein the second inner diameter has a hexagon shape.