Retrograde cutting instrument

[0001] This application claims the benefit of U.S. Provisional Application Ser. No. 60/942,614 filed on Jun. 7, 2007, the entire disclosure of which is incorporated by reference in its entirety herein.

[0002] The present invention relates to arthroscopic surgical methods and instruments and, more specifically, to a retrograde cutting instrument and methods of retrograde repairs and reconstructions.

[0003] During arthroscopic surgery, a small incision is made in the skin covering the arthroscopic site or joint so that surgical instruments may be placed in the joint and manipulated through arthroscopic visualization. As only a very small incision is made during arthroscopic surgery, it is often difficult to handle instruments within the joint capsule, where visibility and access to the structures of the joint capsule is minimal. It is also difficult to manipulate instruments during the formation of a recipient site socket (for example, a femoral or tibial tunnel) during reconstructive surgery, with minimal bone loss and reduced intraarticular bone fragmentation of tunnel rims.

[0004] Accordingly, a need exists for a surgical cutting instrument that is configured to allow improved handling of the instrument within a joint capsule, for example the knee capsule, during ACL reconstruction. A need also exists for a surgical cutter that is stable during knee arthroscopy and that provides drilling of femoral and tibial sockets or tunnels independently of one another and minimizes incisions of distal cortices and reduces intraarticular bone fragmentation of tunnel rims. Instruments and methods for creating a recipient site socket from the inside out, i.e., using a retrograde technique is also needed, as well as a technique for inserting a replacement osteochondral core or implant in recipient sockets formed in a retrograde manner.

[0005] The present invention provides a retrograde cutter that creates a recipient site socket from the inside out, i.e., using a retrograde technique, with minimal incisions of distal cortices and reduced intraarticular bone fragmentation of tunnel rims.

[0006] The retrograde cutter of the present invention is provided with a cutting blade that is configured to engage the shaft of the instrument and to lock into the shaft. The retrograde cutter of the present invention may be employed in a retrograde manner to form a recipient socket (to accommodate an osteochondral transplant, or to allow retrograde fixation of a graft within two sockets, for example).

[0007] Other features and advantages of the invention will become apparent from the following description of the invention, which refers to the accompanying drawings.

[0017] In the following detailed description, reference is made to various specific embodiments in which the invention may be practiced. These embodiments are described with sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be employed, and that structural and logical changes may be made without departing from the spirit or scope of the present invention.

[0018] The present invention provides a retrograde cutter that creates a recipient site socket from the inside out, i.e., using a retrograde technique, with minimal incisions of distal cortices and reduced intraarticular bone fragmentation of tunnel rims.

[0019] The retrograde cutter of the present invention is provided with a cutting blade that is configured to engage the shaft of the instrument and to lock into the shaft.

[0020] The retrograde cutter of the present invention may be employed in a retrograde manner to form a recipient socket (to accommodate an osteochondral transplant, or to allow retrograde fixation of a graft within two sockets, for example). As described in more detail below, formation of the recipient socket begins by inserting an outer tube and an inner tube of the instrument (together with a knurled nut) into the joint space, preferably from the outside in, through a small diameter tunnel. A cutting blade is then attached to the outer tube of the instrument by engaging the outer diameter of the instrument. The blade is locked into the instrument by engaging a locking mechanism (for example, a tongue) of the outer tube. A socket is created by conducting a drilling operation while the device is pulled in a retrograde manner.

[0021] Referring now to the drawings, where like elements are designated by like reference numerals, FIGS. 1-7 illustrate various views and various components of a retrograde cutter 100 of the present invention. FIG. 8 illustrates a schematic view of the retrograde cutter 100 of FIGS. 1-7 provided in the vicinity of a knee in which ACL reconstruction is conducted according to the present invention. The retrograde cutter 100 creates a recipient site socket from the inside out, i.e., using a retrograde technique, with minimal incisions of distal cortices and reduced intraarticular bone fragmentation of tunnel rims.

[0022] As illustrated in FIGS. 1-7, retrograde cutter 100 (FIGS. 3, 6 and 7) includes a cannulated elongated outer tube 10 having a distal end 12 and a proximal end 13 (FIG. 1). Distal end 12 is provided (at its most distal part) with a locking mechanism 15 (for example, a protuberance or tongue 15) that is configured to engage a corresponding structure of blade 30 to be attached and securely engaged to the outer tube 10.

[0023] The outer tube 10 of the retrograde cutter 100 houses an inner tube 20 (FIG. 2) with a diameter smaller than that of the outer tube 10. As shown in FIGS. 1 and 2, the outer tube 10 has a length L₁ which is smaller than length L of the inner tube 20 (length L also represents the total length of the instrument). The difference in lengths L₁ and L is represented by length L₄, which is the length of a knurled nut 40. Knurled nut 40 (FIG. 5) is configured to be removably attached to tubes 10 and 20, and to be actuated to allow engagement of cutting blade 30.

[0024] FIG. 3 illustrates cutter 100 with blade 30 provided at distal end 12 of the outer tube 10. Details of a specific exemplary embodiment of the blade 30 of the retrograde cutter 100 are illustrated in FIGS. 4(a)-(b); however, the invention contemplates other shapes and geometries for the blade 30.

[0025] Blade 30 illustrated in detail in FIGS. 4(a)-(b) has an overall circular or disk-like configuration. Blade 30 is configured to engage the shaft or outer tube 10 of the instrument 100 and to lock onto it. In an exemplary embodiment, blade 30 engages locking mechanism 15 (for example, tongue 15 as shown in FIG. 1) of shaft 10. A longitudinal slot 35 is provided through the blade 30 (fully extending from upper surface 32a to lower surface 32b) and for less than the diameter of the blade, as shown in FIGS. 4(a)-(b). The width W of the slot 35 is about equal to the width of tongue 15 of the outer tube 10, to allow secure engagement of the blade to the tube.

[0026] As also shown in FIGS. 4(i a)-(b), blade 30 is provided with a plurality of teeth 33 on a surface facing the proximal end of the outer tube 10 in the assembled state (i.e., on lower surface 32b of the blade 30).

[0027] In use, the outer tube 10, the inner tube 20 and the knurled nut 40 (FIG. 5) are inserted into a joint, from the distal side, until they are visible in the joint. The knurled nut 40 is unscrewed several turns and pushed proximally, until sufficient space is made available between outer tube 10 and inner tube 20 (to allow engagement of cutting blade 30).

[0028] Blade 30 is subsequently pushed into place (with cutting teeth 33 facing distally) to engage locking mechanism (tongue) 15 of the outer tube 10. The counter bore also engages the outside diameter of tube 10. The knurled nut 40 is then turned to draw inner tube 20 distally, therefore locking all parts of the retrograde cutting instrument 100 together.

[0029] Once the blade is locked onto cutting instrument 100, a drilling operation, for example, a retrograde drilling step, may be subsequently carried, as known in the art. According to an exemplary embodiment only, the retrograde cutter of the present invention may be employed in a retrograde manner to form a recipient socket (at the location of an osteochondral lesion developed on the head of the tibia, for example, or to accommodate retrograde fixation of a graft within two sockets). For example, FIG. 8 illustrates a schematic anterior view of a knee 99 with cutter 100 of FIGS. 1-7 in the vicinity of femur 91 and tibia 93. An exemplary method of ACL reconstruction may be performed according to an embodiment of the present invention by employing cutter 100 of FIGS. 1-7 to form at least one of a femoral and tibial socket. For example, with the instrument 100 oriented as shown in FIG. 8, a tibial socket or tunnel is formed within tibia 93 in a retrograde manner.

[0030] The present invention may be used to form various sockets or tunnels to allow fixation of a graft (for example, a semitendonosus allograft) or to allow replacement of osteochondral cores or implants in a retrograde manner, to obviate inserting harvesters into the joint. For example, cutting instrument 100 of the present invention may be employed for the formation of sockets during an “All-Inside ACL RetroConstruction” for ligament repair, developed by Arthrex, Inc. of Naples, Fla. (and disclosed in U.S. application Ser. No. 60/947,290, the disclosure of which is herein incorporated by reference), which comprises, for example, the steps of: (i) drilling at least one of a femoral and tibial tunnel or socket using a retrodrill technique employing the cutting instrument 100 of FIGS. 1-7; (ii) providing a graft (soft tissue graft or BTB graft) in the vicinity of the sockets; and (iii) securing the graft within the femoral and tibial tunnels (sockets).

[0031] According to yet another embodiment, an exemplary method of ACL retrograde reconstruction of the present invention comprises, for example, the steps of: (i) drilling a femoral socket; (ii) drilling a tibial tunnel or socket using a retrodrill technique employing the cutting instrument 100 of FIGS. 1-7; (iii) providing a graft (soft tissue graft or BTB graft) in the vicinity of the sockets; (iv) securing the graft (soft tissue graft or BTB graft) to a continuous loop/button construct comprising a button with an oblong configuration and provided with an inside eyelet that allows the passage of the continuous loop, preferably a suture loop; (v) passing the graft with the button through the femoral tunnel; (vi) securing the button to the femoral cortex once the button exits the femoral socket; and (vii) securing the graft in the tibial tunnel or socket.

[0032] Although the above-detailed methods of socket formation using the cutter 100 of the present invention have been described with reference to a specific ACL reconstruction (i.e., a specific “All-Inside ACL RetroConstruction” for ligament repair), the invention is not limited to this exemplary embodiment, and contemplates any repairs and reconstructions that employ a cutting instrument such as cutter 100 of the present invention.

[0033] Although the present invention has been described in relation to particular embodiments, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.