There are no related applications.
1. Field of Invention
The field of art to which this invention relates is generally directed to suture anchors and associated suture anchor installation tools and more specifically to a suture anchor constructed of allograft bone which is oriented by the installation tool into a specific orientation within a bore cut into a human bone to secure a suture in body tissue.
2. Description of the Prior Art
As the treatment of injuries to joints and soft tissue has progressed, a need has developed for medical devices which can be used to attach tendons, ligaments and other soft tissue to bone. When surgically repairing an injured joint, it is preferable to restore the joint by reattaching the damaged soft tissues such as ligaments and tendons to bone rather than replacing them with an artificial material. An increase in the incidence of injuries to joints involving soft tissue has been observed. This increased incidence may be due, at least in part, to an increase in participation by the public in various physical activities such as sports and other recreational activities. These types of activities may increase the loads and stress placed upon joints, sometimes resulting in joint injuries with corresponding damage to associated soft tissue. There are well over 500,000 surgical procedures performed in the United States annually in which soft tissue was attached to a bone in various joints including the shoulder, hip and knee.
One conventional orthopedic procedure for reattaching soft tissue to bone is performed by initially drilling holes or tunnels at predetermined locations through a bone in the vicinity of a joint. The surgeon approximates soft tissue to the surface of the bone using sutures threaded through these holes or tunnels. This method is a time consuming procedure resulting in the generation of numerous bone tunnels. The bone tunnels, which are open to various body fluids and infectious agents, may become infected or break and complications such as a longer bone-healing period may result. One known complication of drilling tunnels across bone is that nerves and other soft tissue structures may be injured by the drill bit or orthopaedic pin as it exits the far side of the bone. Also, it may be anatomically impossible or at least very difficult to reach and/or secure a suture that has been passed through a tunnel. When securing the suture or wire on the far side of the bone, nerves and soft tissues can become entrapped and damaged.
Screws are also used to secure soft tissues adjacent to the bone surface. Screws suffer from the disadvantage that they tend to loosen with time, thereby requiring a second operation to remove the loosened screw. In addition, when the screws are set in bone, the heads of the screws frequently protrude above the surface of the bone in which they are set, thereby presenting an abrasive surface which may create wear problems with surrounding tissue. Once a hole has been made in the bone it may be impossible to relocate the hole a small distance away from its original position due to the disruption of the bone structure created by the initial hole. Finally, the nature of a screw attachment tends to require a flat attachment geometry; namely that the pilot hole must generally be located on a relatively flat section of the bone, and toothed washers must frequently be used in conjunction with the screws to fasten the desired objects to the target bone. As a result of these constraints, it may be necessary to locate the attachment point at less than an optimal position.
Staples are also used to secure soft tissue adjacent the bone surface. Staples suffer from their own set of disadvantages and must frequently be removed after they have been in position for some time, thereby necessitating a second operation. In addition, staples must generally be positioned so as to maximize their holding power in the bone which may conflict with the otherwise-optimal position for attachment of the objects to bone. Staples have also been known to crack the bone during deployment, or to accidentally transect the object (e.g. soft tissue) being attached to the bone, since it tends to be difficult to precisely control the extent of the staple's penetration into the bone. Additionally, once the staple has been set into the bone, the position of the staple is then effectively determined, thereby making it impossible to later adjust the position of the staple or to adjust the degree of tension being applied to the object which is being attached to the bone without using a new staple.
In order to overcome a number of the problems associated with the use of the conventional soft tissue to bone attachment procedures, suture anchors have been developed and are now frequently used to attach soft tissue to bone. A suture anchor, commonly referred to as a bone anchor, is an orthopedic, medical device which is typically implanted into a cavity drilled into a bone. In the present application, the device will be referred to as a suture anchor. The bone cavity is typically referred to as a bore hole and if it does not extend through the bone, it is typically referred to as a “blind hole”. The bore hole is typically drilled through the outer cortical layer of the bone and into the inner cancellous layer. The suture anchor may be engaged in the bore hole by a variety of mechanisms including friction fit barbs which are forced into the cancellous layer of bone or by threading into pre-threaded bores in the bone mass or by using self tapping threads. Suture anchors have many advantages including reduced bone trauma, simplified application procedures, and decreased likelihood of suture failure. Suture anchors may be used in shoulder reconstruction for repairing the glenohumeral ligament and may also be used in surgical procedures involving rotator cuff repair, ankle and wrist repair, bladder neck suspension, and hip replacement.
Suture anchors typically have a hole or opening cut therein for receiving a suture. The suture extends out from the anchor and bore hole and is used to attach soft tissue. The suture anchors presently described in the art may be made of absorbable materials which absorb over time, or they may be made from various non-absorbable, biocompatible materials. Although most suture anchors described in the art are made from non-absorbable materials, the use of absorbable suture anchors may result in fewer complications since the suture anchor is absorbed and replaced by bone over time. The use of absorbable suture anchors may reduce the likelihood of damage to local joints caused by anchor migration. Moreover, when an absorbable suture anchor is fully absorbed it will no longer be present as a foreign body. It is also advantageous to construct the bone anchor out of allograft cortical bone as this material will result in natural filling in of the bore with bone in the original bone base and the elimination of foreign material from the site.
It is desirable that a suture anchor be of a small size to minimize damage to the tissue in which the suture is anchored and that the suture anchor be easily attached and hold the suture firmly in place. A number of different suture anchors exist in the prior art including a barb-type anchor, a threaded or screw type anchor, and insert type anchor and a wedge type anchor.
In practice, wedge type anchors with attached sutures are introduced with an insertion tool into a bore drilled into the bone at the location where the body tissue is to be attached. The suture anchor generally includes a first gripping portion in the form of a sharp edge or a point and is designed to rotate as it enters the bore or is in the process of being withdrawn from the bore. As the suture anchor rotates the first gripping portion penetrates the cancellous wall of the bore and causes further rotation of the anchor. At the opposite end of the suture anchor, a second gripping portion is provided which penetrates into the cancellous wall of the bore opposite the first gripping portion as the suture anchor is rotated wedging the suture anchor within the bore in a seated position where it is anchored in the bone and ready to have adjacent body tissue attached thereto.
U.S. Pat. No. 5,683,418 issued Nov. 4, 1997 is directed toward an extruded or injection molded suture anchor which provides an offset force to the suture. The insert is constructed of bioabsorbable polymer material or a non-absorbable material such as metal. The suture anchor as shown in
U.S. Pat. No. 6,306,158 issued Oct. 23, 2001 is directed toward a generally quadrilateral shaped body constructed of a bioabsorbable material such as polylactic acid, polydioxanone, polyglycolic acid and similar materials. The suture anchor may also be constructed of cortical bone where the bone is autologous or autogenous bone. The body of the anchor has a flat bore-abutting surface with a leading gripping edge at one end of the bore-abutting surface defined by a inclined planar side which intersects the planar abutting surface at an acute angle and a trailing gripping edge at the other end defined by an opposing planar side which intersects the planar abutting surface at an acute angle. The leading edge and the trailing edge are connected by the closing surface which has an arcuate portion and a linear portion engaging the leading and trailing gripping edges opposite the bone-abutting surface. The body defines a transverse bore and a bore to receive an insertion anchor. A second divisional U.S. Pat. No. 6,635,074 issued Oct. 21, 2003 having an identical specification and drawings to the '158 patent is directed toward a kit for anchoring a suture in a bore.
U.S. Pat. No. 5,540,718 issued Jul. 30, 1996 is directed toward a conical suture anchor having a bore in which an end of an insertion tool is inserted. When the suture anchor is placed within cancellous bone tissue, the shape memory of the insertion tool urges the suture anchor to its original position so that the suture anchor cannot fit through the bone hole thereby anchoring the same in the human bone.
U.S. Pat. No. RE 36,974 issued Nov. 28, 2000 reissued from U.S. Pat. No. 5,496,348 discloses an anchor with a tubular body having a width less than its length for securing a suture in the body. The anchor includes a tubular wall having a central axis with both ends free of axially inwardly extending slots and an inner surface extending for the entire length of the tube which defines a central opening extending between the proximal end and the distal end and a plurality of transverse throughgoing apertures. The anchor has an anchoring orientation in the body achieved by manipulation of the distal end of the anchor by pulling on a second end portion of the suture.
The above noted '974 patent is a division of application Ser. No. 08/344,466 now U.S. Pat. No. 5,527,343 which is a division of application Ser. No. 08/062,295 now U.S. Pat. No. 5,403,348. The disclosure, specification and drawings of both of these patents is identical to that of the '974 patent with the claims of the '343 patent being directed towards a method for insertion of a suture anchor and the claims of the '348 patent being directed toward an apparatus.
U.S. Pat. No. 4,899,743 issued Feb. 13, 1990 discloses a suture anchor and installation tool which comprises an elongated member having a first end and a second end and a slot extending from the first end towards the second end, the slot being sized to accommodate the suture anchor's barb. The suture anchor is cylindrical with a barb affixed to the distal end and an inclined distal end surface disposed at an angle of approximately 30 degrees to the suture anchor's longitudinal axis. A angled bore is cut through a side wall and the body of the suture anchor is placed at an angle to the face of the inclined distal end surface. When the suture anchor bottoms out in the bone hole, and the elongated member is thereafter withdrawn, the barb's engagement with the bone wall will cause the suture anchor to separate from the elongated member, leaving the suture anchor (and its attached suture) anchored securely in the bone.
Another patent, U.S. Pat. No. 4,823,794 issued on Apr. 25, 1989 discloses a surgical pledget with a V shaped lead-in to a suture entrance slit extending through the pledget from a side wall to a central suture location within the pledget and means for retaining the suture at the suture hole so that the pledget may be positioned on a medial portion of a suture.
U.S. Pat. No. 5,683,418 issued on Nov. 4, 1997 discloses a suture anchor fabricated from extruded material having a throughgoing bore which provides an offset pulling force. The preferred embodiment of the suture anchor as shown in
Although suture anchors for attaching soft tissue to bone are available for use by the orthopedic surgeon, there is a need in this art for novel suture anchors having improved performance characteristics, such as ease of insertion and greater resistance to “pull-out”.
The present invention is directed toward a suture anchor constructed of animal bone preferably cortical allograft human bone which has a first distal end with a rounded end wall, angled planar side walls intersecting said first distal end forming sharp end surfaces therewith, the opposite ends of the side walls ending in a dome shaped proximal end forming a generally triangular cross section. The first distal end has a length which is greater than the length of the outer surface of the proximal end with the length of the distal end also being greater than the diameter of the bore hole in which it is to be placed. A throughgoing bore is formed in the body of the suture anchor to hold suture strands and the suture body is mounted within an outer tube lumen of a driver instrument. The driver instrument has a driver rod with a camming tip which is extending forward by the surgeon to orient the suture anchor into a desired orientation as the suture anchor is transported in the outer tube lumen.
It is thus an object of the present invention to provide a suture anchor which can be formed in a very small size.
Therefore, it is another object of the present invention to provide a suture anchor which is simple to apply and is mechanically stable when implanted in bone tissue.
It is still another object of the invention to provide an improved bone anchor installation tool which is easy to manufacture and easy to use.
It is yet another object of the invention to provide an improved bone anchor installation tool whereby the bone anchor is precisely oriented in a predetermined manner.
It is a further object of the present invention to provide an absorbable suture anchor made of allograft cortical bone.
Accordingly, one of the objects of the present invention is to provide an allograft suture anchor which promotes the use of natural bone growth in the bone bore.
Yet another object of the present invention is to provide a novel suture anchor for anchoring one end of a piece of conventional suture in bone which anchor will attach itself securely to the target area of a bone bore and which has virtually no tendency to migrate from its deployment site.
Still another object of the present invention is to provide a novel suture anchor for anchoring one end of a piece of conventional suture in bone which has high tissue acceptability, prevents back out and is reliable in use.
These and other objects, advantages, and novel features of the present invention will become apparent when considered with the teachings contained in the detailed disclosure along with the accompanying drawings.
The preferred embodiment and the best mode of the suture anchor of the invention is shown in
The suture anchor 20 is adapted for insertion into a hollow tube 66 of an insertion tool 50 which is shown in
The suture anchor 20 can be used to anchor the suture 100 in body tissue such as a piece of bone 201 having a harder outer layer of cortical bone 202 and a softer inner layer of cancellous bone 204. A fairly well defined boundary separates the outer layer cortical from the inner cancellous layer. A hole or bore 200 is provided in the bone 201 to receive and hold the anchor 20 in the bore 200.
In operation, an opening in the nature of a bore 200, which by way of a non-limiting example is 3.5 mm in diameter, is drilled through the layer of cortical bone 202 into the softer cancellous layer 204. Once the bore 200 is formed, the boring bit of the drill is removed and the suture anchor 20 is then prepared for insertion. In operation, the suture 300 is threaded through the central aperture 32 of the bone anchor 20, the bone anchor is mounted in tube 66 and the suture is pulled through the slots 67 formed on each side of the tube 66 along the barrel of the tube 66 through the respective channels in the handle and past the chamber 96. There are no knots holding the suture to the anchor as knots tend to weaken the system. The suture strands are held in place by button 94 which holds the suture strands 300 in a friction fit. The driver tool tube 66 is inserted into the bore 200 cut in the human patient and the anchor 20 is oriented through action of the driver rod 68 which is pushed forward by the push button assembly 80. The suture anchor 20 is ejected into the bore 200 and wedged into the cancellous bore portion 204 of the patient by pulling the suture 300 thus placing a pullout force on the suture anchor 20. As the suture anchor 20 is wedged into the cancellous bone 204 it becomes deeper seated and increases the peak load. The surgeon can then attach the suture opposite the suture anchor 20 to the soft tissue (not shown) and pull the soft tissue to the bone 200. Because the suture is a single piece of material, the failure strength is the suture line break strength rather than the pull out strength where two separate pieces of suture are used. Pull out of the anchor is also diminished because of the deeper seating of the suture in the bone anchor and encompassing bone mass. While various dimensions of the bore and suture anchor have been set forth it should be noted that these can vary depending upon the surgeon's preference.
In the foregoing description, the invention has been described with reference to a particular preferred embodiment, although it is to be understood that specific details as shown are merely illustrative, and the invention may be carried out in other ways without departing from the true spirit and scope of the following claims.