Method and apparatus for attaching connective tissues to bone using a cortical bone anchoring device

#This invention relates generally to methods and apparatus for attaching soft tissue to bone, and more particularly to anchors and methods for securing connective tissue, such as ligaments or tendons, to bone. The invention has particular application to arthroscopic surgical techniques for reattaching the rotator cuff to the humeral head, in order to repair the rotator cuff.

#It is an increasingly common problem for tendons and other soft, connective tissues to tear or to detach from associated bone. One such type of tear or detachment is a “rotator cuff” tear, wherein the supraspinatus tendon separates from the humerus, causing pain and loss of ability to elevate and externally rotate the arm. Complete separation can occur if the shoulder is subjected to gross trauma, but typically, the tear begins as a small lesion, especially in older patients.

#To repair a torn rotator cuff, the typical course today is to do so surgically, through a large incision. This approach is presently taken in almost 99% of rotator cuff repair cases. There are two types of open surgical approaches for repair of the rotator cuff, one known as the “classic open” and the other as the “mini-open”. The classic open approach requires a large incision and complete detachment of the deltoid muscle from the acromion to facilitate exposure. The cuff is debrided to ensure suture attachment to viable tissue and to create a reasonable edge approximation. In addition, the humeral head is abraded or notched at the proposed soft tissue to bone reattachment point, as healing is enhanced on a raw bone surface. A series of small diameter holes, referred to as “transosseous tunnels”, are “punched” through the bone laterally from the abraded or notched surface to a point on the outside surface of the greater tuberosity, commonly a distance of 2 to 3 cm. Finally, the cuff is sutured and secured to the bone by pulling the suture ends through the transosseous tunnels and tying them together using the bone between two successive tunnels as a bridge, after which the deltoid muscle must be surgically reattached to the acromion. Because of this maneuver, the deltoid requires postoperative protection, thus retarding rehabilitation and possibly resulting in residual weakness. Complete rehabilitation takes approximately 9 to 12 months.

#FIG. 1 is a perspective view of a presently preferred embodiment of the inventive bone anchor device, shown in a fully expanded configuration;

#FIG. 2 is a perspective view similar to that of FIG. 1, illustrating the inventive bone anchor device in a folded configuration;

#FIG. 3 is a proximal plan view of the inventive bone anchor device wherein tension has been applied to each end of the device so that it is held in a circular profile;

#Referring now more particularly to the drawings, there is shown in FIG. 1 a bone anchor 10 constructed in accordance with an embodiment of the present invention, comprised of an elliptical disk 12 with a generally circular aperture 14 in its center. In this first embodiment, the disk 12 is fabricated of flat stock, preferably 301 stainless spring steel, or other biocompatible equivalent material, and has a thickness of approximately 0.031 inches. First and second slits 16a and 16b, respectively, formed in a generally “T” shape when viewed from the side, are cut into each side of the annular disk from its distal end, using electro-discharge machining (EDM) techniques, or the like, and are spaced approximately 180 degrees from each other about the periphery of the disk. The “T” shaped slits 16a, b are cut entirely through the annular sidewall 17 of the disk 12, and function to allow the disk to be bent in an upward or proximal direction for deployment into a portion of bone, as shall be more particularly described in connection with FIG. 2, below, and also to prevent “bend-back” when the disk returns to its flat or unfolded configuration (meaning that the slits will assist in preventing the disk from over-bending into a downward or distal direction as it returns to its unfolded configuration). The circular aperture 14 has first and second axially oriented grooves or channels 18a and 18b, respectively, in its inside surface 19, which are preferably spaced approximately 180 degrees apart and are offset about 90 degrees from each slit 16a, b. The aperture 14 permits the deployment of a suture securing apparatus into the desired bone structure distally through the inventive device, and also receives and permits passage of suture material therethrough.

#In FIG. 2 the elliptical disk 12 has been bent upward or proximally into what might be described as a generally “V” shape by exerting tension on each end of the disk at locations about 90 degrees displaced from each of the “T” shaped slits 16a, b. Such applied tension, the application of which in the illustrated embodiment will be discussed in greater detail hereinbelow, causes the thinner area 20a, 20b of the proximal end of the disk formed as a result of the presence of the T shaped slits 16a, 16b, which is preferably fabricated to have a thickness of approximately 0.006 inches from the proximal end of the T shaped slit to the proximal end of the disk 12, to bend about an axis X (FIG. 3), which axis lies generally transversely to a longitudinal axis Y (FIG. 5) for as long as such tension is continually exerted. When the tension is released, the spring-like action of the thinner profile formed at the proximal ends of such “T” shaped slits 16a, b acts to cause the disk to return to its original flat profile.

#FIG. 3 is a proximal view of the inventive device as it appears with tension being applied to each end of the elliptical disk as described in connection with FIG. 2, above. It can be seen from FIG. 3 that applying such tension to the disk 12 causes it to be held in a circular profile. This circular profile allows the device to be inserted into a length of hypotubing for deployment arthroscopically into the desired surgical area by means of a trocar. The device is inserted through a length of hypotubing such that it is deployed at the juncture between the cancellous and cortical bone structures as shall be more fully illustrated hereinbelow.