Abstract:
An insert-molded suture anchor with a biodegradable polymer body in which a loop of suture is totally contained within the polymer. The suture anchor body features a drive end that is shaped to be received into a recess in the end of a hand driver. Anchoring ribs are formed along the remaining length of the anchor. The loop of suture which includes and eyelet for attaching a suture strand is totally embedded within the anchor body during the insert-molding fabrication process. The anchor is produced by placing the suture in an injection mold, and injecting biodegradable polymer into the mold.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 60/750,061, filed Dec. 14, 2005, the disclosure of which is incorporated by reference herein in its entirety. This application is also a continuation-in-part of U.S. application Ser. No. 10/083,568, filed Feb. 27, 2002, now U.S. Pat. No. 7,226,469 which is a continuation-in-part of U.S. application Ser. No. 09/495,816, filed Feb. 2, 2000, now U.S. Pat. No. 6,517,564, the disclosures of which are also incorporated by reference herein in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to apparatus and methods for surgically anchoring suture. More specifically, the present invention relates to surgically anchoring suture to bone using a suture anchor with a suture eyelet insert-molded directly within the suture anchor body. 
     DESCRIPTION OF THE RELATED ART 
     Surgical reattachment of soft tissue to bone is a common feature of orthopedic joint repair. Surgical reattachment is indicated when soft tissue tears partially or completely away from bone, for example. Various fixation devices, including suture, screws, staples, wedges, and plugs have been used in the past to secure soft tissue to bone. More recently, threaded and ribbed suture anchors also have been developed. 
     Suture fixation devices, such as anchors and other implants, generally include structure to which suture is attached or secured. U.S. Pat. No. 4,632,100, for example, discloses and claims a threaded suture anchor with a complex press-fitted disc and knot structure which secures the suture to the anchor. In other suture anchors, such as those disclosed in U.S. Pat. No. 5,370,662, the suture is attached to the anchor by passing the suture through an eyelet at the end of the anchor. Problems arise if the structure for attaching the suture fails postoperatively and the suture detaches from the anchor prematurely. In some of the known devices, the suture is also exposed to abrasion or cutting by sharp or rough areas along the walls of the bone canal into which the anchor is inserted. 
     In addition, the eyelet or, in the case of U.S. Pat. No. 4,632,100, the axial opening for receiving the disc to which the suture is knotted, is formed as part of the drive head of the known suture anchors. Forming openings through the drive head of the anchor mechanically weakens the drive head. 
     Various enhancements to the drive head can improve aspects of anchor performance. For example, recessed grooves may be formed on opposite sides of the drive head to receive and protect the suture from the abrasive areas of the suture anchor tunnel. These features, however, also tend to reduce integrity and weaken the drive head. The drive head can be made larger to recover lost mechanical strength lost. In general, however, small anchoring devices are preferred because they are less invasive and cause less trauma. 
     Insert-molding suture into an anchor such that a loop of suture extends from the head of the anchor is described in U.S. patent application Ser. No. 10/083,568. An example of the prior art suture anchor  1  is illustrated in  FIG. 1 . The suture anchor  1  includes a flexible strand  3  inside an anchor body  5 . The flexible strand  3  preferably is formed into a loop and twisted. An exposed portion  7  of the loop extends outside the anchor body  5  at a drive end  9 , opposite a tapered insertion end  11 . The exposed portion  7  of the flexible strand  3  is shown formed into an eyelet to provide an attachment point used for tissue proximation and reattachment. Surgical situations require, however, smaller anchors that need a shallower pilot hole to provide increased protection of the suture loop. 
     Accordingly, a need exists for a suture anchor or implant to which suture is secured against detachment from the anchor and which protects a suture-attachment structure from abrasion and other damage. The protected suture-attachment structure would serve to extend anchor viability during surgical rehabilitation. A soft tissue fixation device configured with a low profile would be particularly useful for reattachment to the glenoid rim, for example. 
     SUMMARY OF THE INVENTION 
     The suture anchor of the present invention overcomes disadvantages of the prior art, such as those noted above, by providing a loop of suture entirely insert-molded within the suture anchor. The suture loop passes around an eyelet opening developed in the drive head. The suture anchor increases suture eyelet viability during rehabilitation. The suture anchor also requires less pilot hole depth than prior devices. 
     Other features and advantages of the present invention will become apparent from the following description of the invention, which refers to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of an insert-molded suture anchor as disclosed in a parent patent application; 
         FIG. 2  is plan view of a suture anchor according to the present invention; 
         FIG. 3  is a proximal end view of the suture anchor of  FIG. 2 ; 
         FIG. 4  is an elevational perspective of the suture anchor of  FIG. 2 ; 
         FIG. 5  is a plan view of the suture anchor of  FIG. 4 ; 
         FIG. 6  is a cut-away view of the suture anchor of  FIGS. 4 and 5 ; 
         FIG. 7  is a proximal end view of the suture anchor of  FIGS. 4-6 ; 
         FIG. 8  is a distal end view of the suture anchor of  FIGS. 4-7 ; 
         FIG. 9  is a plan view of a hand driver for inserting the suture anchor of the present invention; 
         FIG. 10  is an elevation view of the hand driver of  FIG. 9 ; 
         FIG. 11  is a sectional view of the hand driver of  FIG. 9 ; 
         FIG. 12  is a detail view of the drive end of the hand driver of  FIG. 9 ; 
         FIG. 13  is a plan view of an alternative hand driver for a method of capsular plication using the suture anchor according to the present invention; 
         FIG. 14  is an elevation view of the hand driver of  FIG. 13 ; 
         FIG. 15  is a sectional elevation of the hand driver of  FIG. 13 ; and 
         FIG. 16  is a detail view of the drive end of the hand driver of  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     Referring now to the drawings, where like elements are designated by like reference numerals,  FIGS. 2-8  illustrate a suture anchor  100  of the present invention. The suture anchor  100  includes a molded anchor body  25  having a distal end  12  and a proximal end  13 . A length of strand  23  (preferably suture strand) is insert-molded completely within the suture anchor body  25 . The anchor body  25  is made up of a moldable material such as a polymer plastic. An exemplary manufacturing process includes insert-molding the strand (preferably suture strand) within the anchor body  25 . 
     Although the embodiments of the present invention will be described and illustrated below with reference to the strand  23  as being a suture strand, and to the anchor body  25  as being a suture anchor body, it must be understood that the invention is not limited to these exemplary embodiments and contemplates embodiments wherein the strand is formed of any flexible material. Accordingly, the invention contemplates embodiments wherein the strand comprises various combinations of suture and/or additional materials, or a plurality of suture strands, for example. In exemplary embodiments, strand  23  may be formed, for example, of a high strength suture material such as the one described in U.S. Pat. No. 6,716,234 to Grafton et al., the disclosure of which is incorporated by reference in its entirety. 
     The anchor body  25  may be formed of a translucent or transparent polymer material, and is preferably made of bioabsorbable and/or biodegradable materials such as polyglycolic or polylactic acid polymers. Accordingly, suture strand  23  may be visible through the body of the suture anchor  100 . Advantageously, the suture strand  23  and the anchor body  25  are made of materials selected such that suture loop or eyelet  27  will not biodegrade before anchor body  25 . 
     In exemplary embodiments, the material making up the molded suture anchor body  25  is polylactic acid (PLA), a commonly used biodegradable polymer material. Other moldable biodegradable materials known in the art, such as PLDLA, can be also used. 
     As used herein, the term “biodegradable” refers generally to materials that degrade over time in situ. The materials to be included include those described in the relevant literature using terms such as “bioabsorbable” or “bioresorbable,” for example. Biodegradable materials may be natural or synthetic. In situ degradation of the material may be full or partial. Degradation can take place by any mechanism and at any rate. Those of ordinary skill in the art would know that biodegradable materials can be blended to take advantage of different inherent properties related to degradation rates and device strength, for example, that the materials exhibit. 
     As shown in  FIG. 6 , the length of suture  23  is insert-molded completely within the suture anchor body  25 . The length of suture  23  preferably features twists or other surface irregularities to enhance its pullout strength from the suture anchor body  25 . Insert-molded suture strand  23  extends through the anchor from the distal end  12  of the suture anchor  100 . Suture  23  is molded inside the suture body  25  in the intertwined shape illustrated in  FIG. 6 , to increase the pullout strength of the suture from the anchor body. The suture forms a loop or suture eyelet  27  located within drive socket  29  at the proximal end  13  of the anchor  100  near eyelet  35 . The loop  27  is recessed from the proximal end  13  of the anchor body  25  by a distance L 1  ( FIG. 6 ) of about one-third the length L of the drive socket  29  of the anchor, preferably of about one-fourth the length L of the socket  29 . The insert-molded suture loop eliminates the need to precisely orientate the eyelet during anchor insertion to optimize suture sliding characteristics. 
     Strand  23  can be any known type of suture selected according to the size of the anchor and the anticipated application. Strand  23  can be made from biodegradable or non-biodegradable materials. The suture strand  23  is formed to include the looped portion  27  described above. In the preferred embodiment, strand  23  and loop  27  are formed of a high strength suture material such as the one described in U.S. Pat. No. 6,716,234 to Grafton et al., the disclosure of which is incorporated by reference in its entirety. The suture strand  23  may be insert-molded into the anchor in the manner described in U.S. patent application Ser. No. 10/083,568, described above, or U.S. Pat. No. 5,964,783 to Grafton et al., the disclosure of which is incorporated by reference herein. 
     Suture anchor body  25  features a drive end  29  and an opposing tapered insertion end  31 . Preferably, and as illustrated in  FIGS. 4-6 , the insertion end  31  of the suture anchor  100  tapers to a blunt tip. 
     Ribs  33  are formed along a central portion of the suture anchor body  25  to enhance fixation within a bone socket, for example. As illustrated in  FIGS. 4 and 5 , ribs  33  have a truncated, conical shape at an angle of preferably 15° with respect to the longitudinal axis of suture anchor  100 . Each rib may increase in diameter progressively toward the head of suture anchor  100 , reaching a major diameter of about 3.0 mm, for example. Barbs, slots, screw threads, or other anchoring structures, could be formed instead of, or in addition to, ribs  33 . These structures, if provided in addition to the ribs, afford access for ingrowth of bony tissue for enhanced pullout strength. 
     The looped portion  27  of the suture  23  is insert-molded within the drive end  29 . The looped portion  27  is formed around an eyelet  35  developed as an opening through the drive end  29 . Two suture relief grooves  37  ( FIGS. 4 and 7 ) intersect the eyelet and allow additional strands (e.g., suture strands) threaded through the eyelet  35  (for tissue attachment) to extend proximally back from the suture anchor  100  without impeding engagement between the drive head  29  and a hand driver used to install the suture anchor  100 . The additional suture strand, or plurality of suture strands, may be FiberWire composite sutures of alternating colors to maximize repair strength, aid in suture management and provide superior tying characteristics. Optionally, suture anchor  100  of the present invention can be distributed with at least one strand of suture already threaded through the eyelet  35  and grooves  37 . 
     The drive end  29  of the suture anchor body  25  can be tapered for a snug fit into the hand driver. The drive head also can be shaped for rotational engagement with the hand driver. 
       FIGS. 9-16  illustrate various embodiments of drivers  200 ,  300  used to install the suture anchor  100  of the present invention.  FIGS. 9-12  illustrates cannulated driver  200  which may be preloaded with the suture anchor  100  of  FIGS. 2-8  and with suture strands attached to the eyelet  35 . As explained in more detail below with reference to  FIGS. 9-12 , the suture strands are threaded through the cannula of the driver  200  and secured on a hook on the handle of the driver, to allow the proximal end of anchor  100  to be received by a recess in the cannula of the driver  200  so that the suture anchor is driven into a pilot hole. 
     Hand driver  200  ( FIGS. 9-12 ) according to a first embodiment of the present invention includes a cannulated shaft  32  provided with a cannulated handle assembly  34  and a drive head  45 . As detailed below, cleat  36  is provided on the handle assembly  34  for securing suture attached to the eyelet on the suture anchor  100  and passed through the cannulated shaft and handle. The distal tip  38  of the drive head  45  provides a recess  40  which is configured to receive the proximal end  13  of the suture anchor  100  of  FIGS. 2-8 . The outer diameter of the distal end of the driver  200  is preferably less than or equal to the maximum outer diameter of the suture anchor  100 . In an exemplary embodiment, the drive head  35  is rectangularly shaped and has a width and a length which substantially corresponds to the width and length of drive end  29  of suture anchor  100 . Preferably, the drive head is slightly shorter and has a slightly larger width than drive end  29 , so that the fit is not too tight, yet ensures secure engagement for driving the suture anchor  100  into bone. 
     The shaft  32  preferably comprises an elongate, narrow diameter body suitable for use in remote procedures performed through percutaneous tissue punctures, such as arthroscopic, laparoscopic and other invasive procedures and the like. The shaft typically has a length of about 5 cm to about 20 cm, preferably about 15 cm. The diameter of the shaft assembly is sufficiently small to facilitate introduction through access sheaths, cannulas, trocars, and the like, typically being less than about 10 mm, preferably about 5 mm. 
     The handle assembly  34  preferably includes an elongated double hook  39  extending substantially along the length thereof and having a hook at the proximal end and at the distal end thereof, and a clip  36  formed at one end region of the double hook  39 . When driver  200  is engaged with suture anchor  100 , excess lengths of suture passed through the proximal end of driver  200  can be wrapped around the double hook  39 , and the ends of the sutures can be secured in the clip  36 . In this manner, the suture strands can be prevented from becoming tangled or otherwise interfering with the surgeon&#39;s work. 
     Driver  200  is preferably constructed to withstand an application of about 20 in/lb of torque. Preferably, although not necessarily, at least the shaft and drive head are made of stainless steel. However, other materials may be used which provide the necessary strength and rigidity for installing the suture anchor of the present invention into cortical bone. 
     The anchor  100  and driver  200  may be provided to the surgeon as a preformed assembly with the suture strands pre-threaded through eyelet  35  and through the cannula of the driver and secured on the handle. During surgery, for example, the suture anchor  100  is urged into a hole formed in bone. The hole can be formed using a punching or boring tool, for example, driven into the bone. Advantageously, the hole formed in the bone is made deep enough, and the suture anchor  100  is advanced into the hole sufficiently, so that the proximal end of the anchor sits flush with or below the bone surface. Accordingly, the repair leaves a smooth bone surface, minimizing or eliminating abrasion or other damage to surrounding soft tissue. 
     The anchor generally becomes encapsulated by fibrous tissue within six weeks after implantation. Although PLDLA is the most preferred material for the suture anchor of the present invention, as detailed above, other bioabsorbable materials known in the art can be utilized. Preferably, the anchor material is selected so as to absorb or degrade substantially completely within 12-16 months of implantation. 
     Suture anchors according to the present invention can be used for arthroscopic procedures. The anchors also are advantageous for open and mini-open surgical procedures. Specific examples of applicable procedures include cortical bone-soft tissue fixation, Bankart and SLAP shoulder repairs. 
     The suture anchor  100  of the present invention is particularly well suited for reattachment of the glenoid labrum or inferior glenohumeral ligament in patients with primary or recurrent anterior dislocation or subluxation of the shoulder in association with adequate post-operative immobilization. More specifically, the anchor also can be used for repair procedures such as capsulolabral plication, as described below, and in conjunction with a second exemplary embodiment of a driver  300  used in the method of installing anchor  100  of the present invention. 
       FIGS. 13-16  illustrate details of the second exemplary embodiment of driver  300  used to install the suture anchor  100  of the present invention during an arthroscopic procedure, preferably during an open procedure such as mini-open rotator cuff repairs. The driver  300  is different from the driver  200  described above in that driver  300  comprises a slot or side cannulation at the distal tip of the cannulated shaft and defined by break edges  77 . Preferably, driver  300  is employed in capsule plication applications using the anchor  100  of the present invention. Capsulolabral plication is indicated for repair of certain types of shoulder laxity. When pathologically increased anterior laxity is combined with a Bankart lesion, for example, the addition of a capsular plication to the reattachment of the capsulolabral avulsion is recommended. 
     Driver  300  of  FIGS. 13-16  includes a cannulated shaft  52  provided with a cannulated handle  54 . As in the previously-described embodiment for driver  200 , cleat  56  of driver  300  is provided on the handle for securing suture attached to the eyelet of the anchor and passed through the cannulated shaft and handle. The distal tip  58  of cannulated shaft  52  provides a recess  60  which receives the proximal end of suture anchor  100 . Recess  60  is defined by break edges  77 . The outer diameter of the distal end of the driver  300  is preferably less than or equal to the maximum outer diameter of the suture anchor. As illustrated in  FIGS. 13-16 , driver  300  also features a slot  62  which is continuous with recess  60 . 
     An exemplary method of capsular plication proceeds using a 36-inch (91.4 cm) long #2 suture to plicate the capsulolabral complex. Both free ends of the suture are brought out an operative cannula. A spear with an included obturator is introduced through a skin incision or a clear cannula. The tip of the spear is positioned on bone and the obturator is removed. A pilot hole is prepared in bone using either a punch or a drill depending on the surgeon&#39;s preference. With the manual punch, a mallet is used to advance the punch into bone until the punch handle meets the back of the spear and/or the shoulder on the distal part of the punch meets the bone surface. Alternatively, the drill can be attached with a Jacob chuck to a motorized drill and advanced until the stop on the drill bit meets the back of the spear. 
     After the pilot hole is created and the punch or drill is removed, the sterile-packaged anchor  100  is opened to the sterile field using appropriate sterile technique. The anchor is removed and the suture is unloaded from the implant. A separate sterile packaged plication driver  300  is opened to the sterile field. One of the two legs of the plication suture is selected. This suture leg is the one on the medial side, or the one that passes under the tissue. 
     The selected suture leg is loaded through the anchor eyelet. The anchor  100  is positioned on plication driver  300  so that the open side of the eyelet  35  faces the open slot  62  on the driver. The suture leg will exit the slot  62  on the driver  300 . The anchor  100  with driver is introduced into the prepared pilot hole by hand. A mallet may be used to advance the implant into the hole. The anchor is advanced until a second laser line  64  on the distal tip of the driver is flush with the bone surface and a laser line  66  on the proximal part of the anchor driver shaft is flush with the back of the spear handle. 
     The handle is pulled straight off the anchor  100  and the spear is removed. Additional anchors are inserted depending upon the size of the soft tissue defect. Suture passing and knot tying are carried out in the preferred fashion. 
     Advantageously, when the suture anchor  100  is inserted into bone, it is not necessary for the proximal end of the anchor to be countersunk below the bone surface, as is required with prior art devices to prevent tissue abrasion by the exposed eyelet. Consequently, the anchor of the present invention does not need to be inserted as far as the prior art devices. Further, the internally disposed suture eyelet avoids abrasion of the rim of bone. In addition, because the suture anchor of the present invention is provided with a plurality of ribs extending the full body anchor, better fixation in bone is achieved. Finally, the intertwined suture in the present invention provides greater pull-out strength than prior suture anchors. 
     Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. The above description and drawings illustrate preferred embodiments which achieve the objects, features and advantages of the present invention. It is not intended that the present invention be limited to the illustrated embodiments. Any modification of the present invention which comes within the spirit and scope of the following claims should be considered part of the present invention.