Abstract:
A suture anchor is described which in one form may be easily fabricated from extruded material by angular cuts and bore holes which provide an offset pulling force to the suture. In an alternate and preferred embodiment the suture anchor is injection molded having an annular displaced corner and abutment wall which act to seat the suture anchor firmly within a bore hole. Novel application means are also disclosed which hold the suture anchor on a frangible shaft for insertion and upon completion of the insertion permit fracture of the frangible portion and removal of the instrument. In another form of the invention, the suture anchor comprises a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a suture, and means thereon for releasable connection to an inserter shaft; a boundary surface and a plow surface of the body intersecting to form a biting edge at the proximal end of the body; and the boundary surface and an abutment surface of the body intersecting to form a cam surface at the proximal end of the body; and the biting edge being adapted to be in engagement with a first wall portion of a bore in a bone and the cam surface being adapted to be in engagement with a second wall portion of the bore opposed to the first wall portion; wherein tension on the inserter shaft is operable to move the cam portion along the bore second wall portion and rotate the body in the bore such that the biting edge bites into the bore first wall portion to lock the body in the bore.

Description:
This is a continuation of prior U.S. patent application Ser. No. 10/782,344, filed Feb. 19, 2004 by Jack S. Pedlick, Thu Anh Le, John DiGiovanni, Dennis D. Jamiolkowski, and Mark J. Suseck for WEDGE SHAPED SUTURE ANCHOR AND METHOD OF IMPLANTATION, which in turn is a continuation of U.S. patent application Ser. No. 09/923,996, filed Aug. 7, 2001 now U.S. Pat. No. 6,726,707 by Jack S. Pedlick, Thu Anh Le, John DiGiovanni, Dennis D. Jamiolkowski, and Mark J. Suseck for WEDGE SHAPED SUTURE ANCHOR AND METHOD OF IMPLANTATION, which in turn is a continuation of U.S. patent application Ser. No. 09/412,903, filed Oct. 5, 1999 now U.S. Pat. No. 6,270,518 by Jack S. Pedlick, Thu Anh Le, John DiGiovanni, Dennis D. Jamiolkowski, and Mark J. Suseck for WEDGE SHAPED SUTURE ANCHOR AND METHOD OF IMPLANTATION, which in turn is a continuation of U.S. patent application Ser. No. 08/630,389, filed Apr. 10, 1996 now U.S. Pat. No. 5,961,538 by Jack S. Pedlick, Thu Anh Le, John DiGiovanni, Dennis D. Jamiolkowski, and Mark J. Suseck for WEDGE SHAPED SUTURE ANCHOR AND METHOD OF IMPLANTATION, which patent applications are hereby incorporated herein by reference. 

   TECHNICAL FIELD 
   The field of art to which this invention relates is surgical implements and more specifically suture anchors for anchoring suture material to bone. 
   BACKGROUND ART 
   As the treatment of injuries to joints and soft tissue has progressed in the orthopaedic medical arts, there has been a need for medical devices which can be used to attach tendons, ligaments and other soft tissue to bone. When surgically repairing an injured joint, for example, it is often preferable to restore the joint by reattaching the damaged soft tissues rather than replacing them with an artificial material. Such restorations typically require the attachment of soft tissue such as ligaments and tendons to bone. 
   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. In 1991, for example, there were approximately 560,000 surgical procedures performed in the United States in which soft tissue was attached to a bone in various joints including the shoulder, hip and knee. 
   One conventional orthopaedic 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. Then, the surgeon approximates soft tissue to the surface of the bone using sutures threaded through these holes or tunnels. This method, although effective, is a time consuming procedure resulting in the generation of numerous bone tunnels. A 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 is anatomically very difficult to reach and/or secure a suture/wire 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. 
   In order to overcome some of the problems associated with the use of the conventional bone tunnel procedures, suture anchors have been developed and are frequently used to attach soft tissue to bone. A suture anchor is an orthopaedic, medical device which is typically implanted into a cavity drilled into a bone. Although less frequently, these devices have also been referred to as bone anchors. The cavity is typically referred to as a bore hole and usually does not extend through the bone. This type of bore hole is typically referred to as a “blind hole”. The bore hole is typically drilled through the outer cortex layer of the bone hole by a variety of mechanisms including friction fit, barbs which are forced into the cancellous layer of bone, etc. Suture anchors are known to have many advantages including reduced bone trauma, simplified application procedures, and decreased likelihood of suture failure due to abrasion on bone. Suture anchors may be used in the Bankart shoulder reconstruction for repairing the glenohumeral ligament and may also be used in surgical procedures such as rotator cuff repair and hip replacement. Also, such anchors may be used in repair of tendon tears by direct attachment of tendon to bone. 
   Suture anchors typically have at least one suture attached. This may be by means of a hole or opening for receiving the suture(s). At least one end and typically both ends of the suture strand extend out from the bore hole and are 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. In addition, the use of absorbable suture anchors may reduce the likelihood of damage to local joints caused by anchor migration. 
   Although suture anchors for attaching soft tissue to bone are available for use by the orthopaedic surgeon, there is a constant need in this art for novel suture anchors having improved performance characteristics. 
   SUMMARY OF THE INVENTION 
   The device of the present invention calls for an implantable apparatus for wedging within an opening formed within a bone. The apparatus comprises a body which defines a perimeter and said perimeter defining at least one biting edge. A hole is defined by the body through which a suture is received for attachment through the device to the bone. The hole defined by the body may be nearer to one side of the perimeter in order to provide an imbalance of force to increase rotation of the device during the implantation procedure. The body in cross-section may have a perimeter which is substantially in the shape of a triangle, trapezoid or parallelogram. In this way the body may have two slides which diverge in a direction away from said hole, such that the rotation causes an edge formed by one of such sides to bite into the soft cancellous layer of the bone. In order to better distribute the forces acting on the device, the sides may be rounded so that the rounded edge will match with the size of the bore hole provided in the bone. In this way, maximum contact of the edge with the side of the hole in the bone is provided. 
   The edge may be formed by the intersection of planar or rounded sides or a combination of planar and rounded sides in order to optimize the biting action of the edge. The edge may also be provided with a single engaging tooth or a plurality of engaging teeth in order to improve the holding power, biting and/or placement of the device. The device may be triangular in shape and thus formed by three mutually adjacent sides. 
   The apparatus may further include a thin longitudinal stem portion which extends from the body. This stem portion is preferably detachable from the body and may be integral and formed with the body out of the same material and provided with a frangible portion or may be formed separately and fitted to the body. 
   The body may be made of any medical grade material and the stem may be made of a different medical grade material. The body and stem may be joined by a frangible portion which could be formed, for example, by two intersecting web portions in order to provide stability to the device during insertion while still providing the weakness necessary for fracture of the area. 
   The stem may be provided with a protrusion which mates with an implantation device in order to position the stem within the implantation device at an optimum position. 
   The body may be made of bioabsorbable material, a biocompatible metal, or a medical grade polymer for example. The body may be of a medical grade metal material and the stem made of a bioabsorbable polymer such that after fraction the anchor stays implanted but the stem portion remaining after fracture is absorbed by the body. 
   The invention includes a method of implanting a device for holding material in the bone which comprises accessing the bone and forming an opening therein for receipt of the device. The device is then gripped by a stem which extends from the device and is inserted into the opening by gripping such a stem. The stem is then detached from the device and the device is rotated in order to wedge within the opening formed in the bone. 
   The separation of the stem from the device may include either breaking a portion of the stem or device in order to separate the stem and device or separating the stem via a snap fit, interference fit, or other attachment mechanism. 
   The insertion device may include a stabilizing portion to prevent excessive premature rotation of the device and thus prevent premature fracture of any frangible portion of the stem. This however is not necessary in the method where the device is attached to the stem through an interference or frictional fit and the stem is merely removed from an opening in the device during the method of implantation. 
   In another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a suture, and means thereon for releasable connection to an inserter shaft; a boundary surface and a plow surface of the body intersecting to form a biting edge at the proximal end of the body; and the boundary surface and an abutment surface of the body intersecting to form a cam surface at the proximal end of the body; and the biting edge being adapted to be in engagement with a first wall portion of the bore and the cam surface being adapted to be in engagement with a second wall portion of the bore opposed to the first wall portion; wherein tension on the inserter shaft is operable to move the cam portion along the bore second wall portion and rotate the body in the bore such that the biting edge bites into the bore first wall portion to lock the body in the bore. 
   And in another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, the body defining a hole therethrough for retaining a suture, and the body having means thereon for releasable connection to an inserter shaft; the body having first and second opposite and parallel planar sides; the hole extending from the first side to the second side; each of the sides being provided with a rounded entryway leading to the hole, such that the hole is devoid of edges against which the suture can impinge. 
   In still another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and larger proximal end, means thereon for retaining a suture, and means thereon for releasable connection to an inserter shaft; the body distal end being of rounded configuration; a plow surface of the body being of rounded configuration in plan view; an abutment surface of the body opposite from the plow surface being of rounded configuration in plan view; and the abutment surface and a boundary surface of the body intersecting to form, in side elevational view, a rounded configuration; the rounded configurations being operable to guide entry of the body into the bore in the bone and to center the body in the bore. 
   And in yet another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, the body defining a hole therethrough for retaining a suture, and the body having means thereon for releasable connection to an inserter shaft; the hole being substantially elliptical in width-wise cross-section and having a major axis substantially normal to a minor axis; the major axis being aligned with a selected region of the body to direct stress from the suture toward the selected region of the body. 
   In another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, the body defining a hole therethrough for retaining a suture, and the body having means thereon for releasable connection to an inserter shaft; the body having first and second opposite sides; the hole extending from the first side to the second side; each of the sides being provided with a pathway extending from the hole to a boundary surface of the body, the pathway extending into the side of the body further than the diameter of the suture, such that the suture in the hole extends through the pathways and is disposed in the pathways removed from outer surfaces of the body first and second sides. 
   And in another form of the invention, the suture anchor can comprise a substantially wedge-shaped body having a smaller distal end and a larger proximal end, the body having means thereon for retaining a suture, and a boundary surface having means therein for releasable connection to an inserter shaft; the means for releasable connection to an inserter shaft comprising a smooth-walled counterbore in the boundary surface, and a second bore in a bottom of the counterbore, the second bore being adapted to receive a threaded end portion of the inserter shaft and to be threadedly engaged thereby, and the counterbore being adapted to receive a cylindrically-shaped flexible tip portion of the inserter shaft; wherein flexing of the inserter shaft tip portion is permitted by the counterbore substantially without disturbing the engagement of the threaded end portion of the inserter shaft with the second bore. 
   The invention also comprises an installation tool for placing a suture anchor and a suture attached thereto in a bore in a bone, the tool comprising an elongated shroud having therein an internal opening; an inserter shaft slidably disposed in the internal opening; the suture anchor being releasably connected to a distal end of the inserter shaft; the shroud being of elastomeric material and configured to form first and second channels on opposite sides of the internal opening and adapted each to retain a portion of the suture attached to the anchor and extending proximally therefrom; each of the channels being formed such that a first portion of the channel at an outer surface of the shroud is narrower than a second portion of the channel spaced from the shroud outer surface; the suture portions being removable from the channel second portions by passing through the channel first portions, the elastomeric material deforming to allow the passage through the channel first portion. 
   The invention also comprises a bone anchor system comprising a suture anchor having means thereon for releasable connection to an installation tool; and the installation tool for placing the suture anchor and a suture attached thereto in a bore in a bone, the installation tool comprising an elongated shroud having an internal opening, and an inserter shaft slidably disposed in the internal opening, the inserter shaft comprising a proximal rigid portion connected to a distal flexible portion, the distal flexible portion being adapted to releasably connect to the suture anchor. 
   In another form of the invention, the bone anchor system comprises a suture anchor comprising a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a suture, and a boundary surface having means thereon for releasable connection to an inserter shaft; a suture connected to the anchor by the suture retaining means; and an inserter shaft connected to the anchor by the boundary surface inserter shaft connection means, the inserter shaft comprising an elongated rod having a handle at a proximal end thereof and the anchor disposed at a distal end thereof, the handle being generally of a “T” configuration in which the head of the “T” is angled 5°–45° off normal to the axis of the rod, the handle being configured such that the head of the “T” fits a palm of an operator&#39;s hand and a portion of the head of the “T” extending outwardly and distally from the rod proximal end is adapted to receive a thumb of the hand of the operator. 
   In still another form of the invention, the bone anchor system comprises a plurality of suture anchors, each comprising a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a suture, and means thereon for releasable connection thereof to an inserter shaft; an inserter shaft connected to each of the anchors by the releasable connection means; and a suture connected to each of the anchors by the suture retaining means, the sutures each being visually distinguishable from the remainder of the sutures, such that appropriate pairs of strands of the sutures may be visually identified by an operator. 
   In yet another form of the invention, the bone anchor system comprises a suture anchor comprising a substantially wedge-shaped body having a smaller distal end and a larger proximal end, means thereon for retaining a plurality of sutures, and means thereon for releasable connection thereof to an inserter shaft; an inserter shaft connected to the anchor by the releasable connection means; and a plurality of suture strands connected to the anchor by the suture retaining means, the suture strands being visually distinguishable from each other, such that appropriate pairs of strands of the sutures may be visually identified by an operator. 
   In another form of the invention, the bone anchor system comprises a bone anchor having means thereon for retaining a suture; and the suture retained by the bone anchor; the suture being identifiable by color such that the suture can be distinguished from other sutures of other colors. 
   The present invention also comprises a method for disposing a suture anchor in a bore in a bone, comprising the steps of: 
   providing a suture anchor having thereon means for connecting a suture thereto, means for releasably connecting an inserter shaft thereto, a biting edge thereon, and a rounded cam surface on an opposite side of the anchor from the biting edge, the inserter connecting means being offset from a center of the anchor; and providing an inserter shaft comprising an elongated rod having a handle at a proximal end thereof and at a distal end thereof connected to the anchor by the releasable connecting means; and connecting a suture to the anchor by way of the means for connecting a suture to the anchor; 
   by manipulation of the inserter shaft, inserting the anchor in the bone with the biting edge adjacent a first wall portion of the bore in the bone and the rounded cam surface adjacent an opposite second wall portion of the bore; 
   pulling the inserter shaft so as to cause the rounded cam portion to move along the second wall portion and the anchor to rotate in the bore with the anchor biting edge biting into the first wall portion of the bore, whereby to lock the anchor in the bore with the suture extending from the bore; and 
   disengaging the inserter shaft from the anchor. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described with reference to the accompanying drawings wherein; 
       FIG. 1  is a perspective view of a first embodiment of a suture anchor according to the invention; 
       FIG. 2  is an end view of the suture anchor of  FIG. 1 ; 
       FIG. 3  is a front view of the suture anchor of  FIG. 2 ; 
       FIG. 4  is an end view of the suture anchor of  FIG. 3 ; 
       FIG. 5  is a side view of the suture anchor of  FIG. 1 ; 
       FIG. 6  is a cross-sectional view taken along line  6 — 6  of  FIG. 2 ; 
       FIG. 7  is a perspective view of the suture anchor and implantation portion of the first embodiment; 
       FIG. 8  is a top view of a suture anchor extruded rod blank; 
       FIG. 9  is a view of the implantation procedure of the present invention; 
       FIG. 10  is a view of the implantation procedure upon removal of the implantation device; 
       FIGS. 11 and 12  show an alternative implantation procedure for the device of  FIG. 1 ; 
       FIG. 13  is a perspective view of an alternative embodiment of the suture anchor of the present invention; 
       FIGS. 14   a–d  show various embodiments of the plow edge of the device of the present invention; 
       FIG. 15  is a top view of the suture anchor of  FIG. 14 ; 
       FIG. 16  is a front view of the suture anchor of  FIG. 14 ; 
       FIG. 17  is a cross-sectional view taken along line  17 — 17  of  FIG. 15 ; 
       FIG. 18  is a perspective view of the suture anchor of  FIG. 14  with a unitized implantation device; 
       FIGS. 19 through 22  show the implantation procedure of the suture anchor; 
       FIG. 23  is a perspective view of a metal suture anchor according to the present invention; 
       FIG. 24  is a front view of a molded suture anchor according to the present invention; 
       FIG. 25  is a front view of a molded suture anchor according to the present invention after implantation; 
       FIG. 26  is an alternative instrument for implanting the suture anchor of the present invention; 
       FIG. 27  is a front perspective view of an alternative embodiment of the suture anchor of the present invention; 
       FIG. 28  is a perspective view of an alternative embodiment of the implantation device of the present invention with suture anchor attached; 
       FIG. 29  is a perspective view of the implantation device of  FIG. 28 ; 
       FIG. 30  is a partial cross-sectional view showing implantation of a suture anchor using the device of  FIGS. 28 and 29 ; 
       FIG. 31  is a partial cross-sectional view showing implantation of a suture anchor using the device of  FIGS. 28 and 29 ; 
       FIG. 32  is a partial cross-sectional view showing implantation of a suture anchor using the device of  FIGS. 28 and 29 ; 
       FIG. 33  is an alternative embodiment of the suture anchor of the present invention; 
       FIG. 34  is a partial cross-sectional view showing implantation of the suture anchor using the device of  FIG. 33 ; 
       FIG. 35  is a side view of a suture anchor assembly formed in accordance with the present invention; 
       FIG. 36  is a perspective view of the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 37  is a perspective view of the suture anchor associated with the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 38  is a front view of the suture anchor shown in  FIG. 37 ; 
       FIG. 39  is a sectional view taken along line  39 — 39  of  FIG. 38 ; 
       FIG. 40  is an edge view of the suture anchor shown in  FIG. 37 ; 
       FIG. 41  is a sectional view taken along line  41 — 41  of  FIG. 40 ; 
       FIG. 42  is a proximal end view of the suture anchor shown in  FIG. 37 ; 
       FIG. 43  is a top view of the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 44  is a side view of the main shaft component of the installation tool associated with the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 45  is a distal end view of the main shaft shown in  FIG. 44 ; 
       FIG. 46  is a side view of the shaft tip component of the installation tool associated with the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 47  is a side view of the nose component of the installation tool associated with the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 48  is a sectional view taken along line  48 — 48  of  FIG. 47 ; 
       FIG. 49  is a distal end view of the nose shown in  FIG. 47 ; 
       FIG. 50  is a proximal end view of the nose shown in  FIG. 47 ; 
       FIG. 51  is a perspective view of the distal end of the shroud component of the installation tool associated with the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 52  is an end view of the shroud shown in  FIG. 51 ; 
       FIG. 53  is a perspective view showing the suture anchor assembly of  FIG. 35  in the region where the proximal end of the shroud meets the handle member of the installation tool; 
       FIG. 54  is a view of the outside surface of one half of the handle of the installation tool associated with the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 55  is a view of the inside surface of the handle half shown in  FIG. 54 ; 
       FIG. 56  is a view of the outside surface of the other half of the handle of the installation tool associated with the suture anchor assembly shown in  FIG. 35 ; 
       FIG. 57  is a view of the inside surface of the handle half shown in  FIG. 56 ; 
       FIG. 58  is a view showing the shaft tip, nose and main shaft of the installation tool associated with the suture anchor assembly shown in  FIG. 35 , with the various components being assembled into a sub-assembly; 
       FIG. 59  is a partial view showing the proximal end of the suture anchor shown in  FIG. 37  joined to the distal end of the shaft tip shown in  FIG. 46 ; 
       FIG. 60  is a perspective view of the distal end of the suture anchor assembly shown in  FIG. 35 , with the assembly&#39;s suture element removed; 
       FIG. 61  is a perspective view showing the distal end of the suture anchor assembly shown in  FIG. 35 , with the assembly&#39;s suture element in place; 
       FIG. 62  is a view showing the suture anchor assembly of  FIG. 35  being gripped by the hand of a user; 
       FIG. 63  is a side view showing the distal end of the suture anchor assembly of  FIG. 35  entering a bore hole formed in a bone; 
       FIG. 64  is a view showing the distal end of the suture anchor assembly of  FIG. 35  as the suture anchor is being pushed into the bore hole; 
       FIG. 65  is a view like that of  FIG. 64 , except showing the suture anchor fully deployed in the bone hole, with the installation tool having been removed from the bone; 
       FIG. 66  is a side view showing an alternative form of suture anchor; 
       FIG. 67  is a side view showing the suture anchor of  FIG. 66  being inserted into a bore hole; 
       FIG. 68  is a side view showing the suture anchor of  FIG. 66  fully set in the bore hole; 
       FIG. 69  is a top end view showing the suture anchor of  FIG. 66  disposed in a bore hole; 
       FIG. 70  is a view of a side of an alternative form of suture anchor formed in accordance with the present invention; 
       FIG. 71  is a proximal end view of the suture anchor of  FIG. 70  disposed in a bore hole; 
       FIG. 72  is a perspective view showing another form of suture anchor formed in accordance with the present invention; 
       FIG. 73  is a perspective view showing another form of suture anchor formed in accordance with the present invention; and 
       FIG. 74  is a perspective view showing another form of suture anchor formed in accordance with the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A first aspect of a suture anchor according to the present invention is a unitized suture anchor, particularly as shown in  FIG. 1 . The first embodiment of the invention will now be described with reference to the Figures. The suture anchor  1  has a first abutment end  2  and a second abutment end  3 . The suture anchor has a substantially cylindrical cross-section as shown in  FIG. 2  and the cylindrical longitudinal surface forms with the abutment end  2  a corner  4 . The diameter of the suture anchor is sized smaller than the bore hole or opening in the bone receiving the suture anchor. This permits passage of the suture end(s) out of the opening. A suture opening  5  is defined by the body of the suture anchor  1 . In an alternative embodiment shown in  FIG. 3  the first abutment end  2  and second abutment end  3  are slightly tapered to a point or edge. This is due to the extruding process of formation as will be described below. The suture opening  5  is formed transverse to the longitudinal direction of the suture anchor  1 . Also the suture opening  5  is offset from the center of the suture anchor  1  such that an imbalance is formed in the rotation of the device on implantation as described below. 
   The suture anchor may be formed either by extrusion or by injection molding. When injection molding the suture anchor the implantation structure of  FIG. 7  is preferred. In that Figure it is seen that a shaft  6  is formed attached to one end of the suture anchor  1 . A thinned portion forms a frangible portion  7  which will operate to separate the suture anchor  1  from the shaft  6  upon implantation. 
   Alternatively, if an extrusion process is used a rod of material is extruded as shown in  FIG. 8 . Diagonal cuts along cut lines  8  are made after boring openings  9  in the rod at predetermined intervals. Thus, each of the suture anchors is formed by the cut severing the suture body from the suture body of the adjacent anchor. 
   Now an implantation procedure will be described. With reference to  FIG. 9  the suture anchor  1  has a suture  10  passed through the opening  5 . An appropriate implantation site is created by, for example, boring a hole of predetermined dimension in the bone material slightly larger than the diameter of the suture anchor. The hole may have a diameter of 5 mm for a suture anchor of 3 mm size and is drilled through the outer cortex of the bone into the inner cancellous layer. Upon insertion the suture anchor is placed within the bore hole by the downward motion as shown in  FIG. 9 . An upward tug on the shaft portion  6  causes a series of events to occur. Initially corner  4  digs into the softer cancellous layer of the bone and second abutment end  3  rotates into engagement with the opposite side of the wall. Thus, the anchor is wedged within the opening of the bore hole  11 . The shaft  6  separates from the suture anchor  1  by the breaking of frangible portion  7 . This leaves the suture anchor  1  implanted within the bone while the shaft  6  is removed. This securely implants the anchor within the bone material permitting attachment of soft tissue or other materials through the use of suture  10 . 
   An alternative arrangement for implantation is shown in  FIGS. 11 and 12 . This arrangement may have the suture already in place such that a preloaded anchor and apparatus is provided. The apparatus includes a tube  12  which may be formed to receive therein the suture anchor  1 . The suture  10  is preloaded through the opening  5  defined in the suture anchor and passed up through the tubular portion to a pull tab  13 . An appropriate bore hole  11  is prepared in the bone and the suture anchor and tube are inserted therein. The suture anchor is permitted to drop out of the tubular portion and becomes slightly dislocated with respect to the tube. End  14  of the tube is cut at a slight angle in order to promote the rotation of the suture anchor in a particular direction. For example, as shown in  FIGS. 11 and 12 , the suture anchor is promoted to rotate in a clockwise direction by the longer portion of the tube being on the left side of the figure, that is the longer side of the suture anchor. Once the suture anchor has dropped out of the tube  12 , the pull tab  13  is used to snug up the suture anchor within the opening. By pulling upward on the pull tab, the biasing force of the offset hole acting through the pulling force of the suture firmly anchors the suture within the opening. At this point, the pull tab may be removed and the suture slid from within the tubular portion  12 . 
   An embodiment will now be described with reference to  FIGS. 13–26 . The suture anchor  100  has a body  101  formed in a substantially truncated wedge shape. The body  101  defines a suture opening  102  which is rounded at its openings in order to avoid the likelihood of abrasion to the suture. An abutment wall  103  may be straight but in the preferred embodiment is provided with a radiused surface which extends in a oblique direction of the anchor. This radius is set to match the radius of the bore hole into which the anchor is intended to be inserted. For example a 4 mm diameter hole would be drilled to receive an anchor with a 4 mm radius to abutment wall  103 . A plow wall  104  forms an edge  105  at its intersection with top  106  of the device. The plow wall  104  is also radiused in order to maximize contact between edge  105  and the wall of the bore hole to improve the action of the corner  105  as both a plow and a frictional engagement mechanism for the anchor. 
   The corner of edge  105  may be formed in a plurality of manners. For example, the edge  105 A ( FIG. 14A ) may be straight and squared off at the junction between walls  106  and  104 , or the edge  105  may be formed with a plurality of teeth  105 B to provide additional digging force. Also, the embodiment of  FIG. 14B  may be modified as shown in  FIG. 14C  to provide but a single tooth or point which would initiate the digging effect of the edge  105 C to introduce the remainder of the edge into the soft cancellous layer. Finally, an additional alternative embodiment is shown in  FIG. 14D  wherein the edge  105  is actually a point  105 D and the plow wall  104  is actually an edge such that the body of the anchor has a substantially conical or cylindrical cross section. 
     FIG. 18  shows a shaft  107  that extends from the top of the suture anchor prior to insertion of the device into the bore hole. The shaft  107  has formed therein frangible portion  108  in this case formed by a pair of intersecting webs  109 . This structure is preferred in the unitized injection molded form of the device as it provides stability between the shaft and suture anchor by maximizing the area moment of inertia of the cross-section while still maintaining a weakness to separation permitting fracture at the frangible portion by minimizing the cross-sectional area. 
   A stop  110  is provided in order to locate the device in an insertion apparatus prior to implantation. The entire device is injection molded out of a polymer material. The angles of junction for the abutment wall  103  and the top  106  range from about 60° to about 140° and if preferably about 105°. The angle for corner  105  at the juncture of plow wall  104  and top  106  ranges from about 20° to about 90° and preferably about 55°. 
   The anchors of the present invention may be made from either conventional bioabsorbable materials or conventional non-absorbable materials, combinations thereof and equivalents thereof. Examples of absorbable materials include homopolymers and copolymers of lactide, glycolide, trimethylene carbonate, caprolactone, and p-dioxanone and blends or other combinations thereof and equivalent thereof. Of particular utility are the polylactides, especially poly[L(−)lactide], and the lactide-rich lactide/glycolide copolymers, especially 95/5 poly[L(−)lactide-co-glycolide]. 
   Examples of non-absorbable materials from which the suture anchors of the present invention may be made include metallic biocompatible materials including stainless steel, Nitinol, titanium, Vitalium and equivalents thereof, polymeric materials such as non-absorbable polyesters, polyamides, polyolefins, polyurethanes, and polyacetals and equivalents thereof. 
   The bonding of the anchors of the present invention to bone may be advantageously increased by promoting bone growth. This can be accomplished by having a microporous surface into which the bone can rapidly grow to aid fixation. This may be particularly advantageous in the case of a metallic anchor, especially a titanium or titanium alloy anchor, but may also provide benefit in the case of polymeric anchors of the present invention, especially those made of absorbable materials. Other methods include the coating of the anchor&#39;s surface with a substance to promote adhesion to the bone. Such coatings include the hydroxyapatite-containing-glass coatings described by Ishikawa, et al., in the article “Effect of Hydroxyapatite Containing Glass Coating on the Bonding between Bone and Titanium Implants” appearing in Clinical Materials, Volume 14, 1993, pages 277–285. 
   It is further noted that the anchors of the present invention can be made to contain growth factors, especially bone growth factors, that can advantageously increase the effectiveness of the anchors, especially in the area of fixation. This may be accomplished in a number of ways, including via coatings or, in the case of absorbable materials, by incorporating the growth factors within the device and allowing them to diffuse out. 
   The suture anchor devices of the present invention, when made form an absorbable material, are preferably manufactured by molding using conventional injection molding equipment and conventional injection molding processes. A typical molding process includes the steps of (1) injecting a suitable polymer melt into an appropriately designed mold or cavity at process conditions conventionally employed for such polymer systems, (2) releasing from the mold, after the melt cools in the mold, polymer shaped in the proper configuration to meet the design criteria of the device. Additionally the anchor molded from the absorbable polymeric material may be advantageously subjected to an annealing process to increase its mechanical or biological performance. Thermal annealing can also be used to increase the dimensional stability of molded parts by increasing the crystallinity levels in the parts. One or more surgical sutures, or one or more sutures with surgical needles attached, may be used in combination with the suture anchor and may be assembled prior to sterilization. The device can then be sterilized using conventional methods to render the anchor suitable for surgical applications. 
   Referring now to  FIGS. 19 and 20  the implantation procedure is displayed. Referring to  FIG. 19  the suture anchor  100  with shaft  107  attached thereto is inserted into a bore hole after threading of a suture  111  through suture opening  102 . The device is inserted gently into the bore hole until the suture anchor is positioned at a desired location in the hole as shown in  FIG. 19 . It is generally not desired to bottom out the suture anchor. After insertion of the applier (of the type in  FIGS. 28 and 29 ), the shaft is drawn upward forcing the edge  105  to dig into the softer cancellous layer of the bone. The edge digging in on withdrawal of the shaft creates a rotation of the body of the suture anchor which, in combination with the withdrawal tension, breaks the frangible portion  108  and permits removal of the shaft  107  after separation. The suture anchor itself rotates fully until abutment wall  103  is engaged firmly against the surface of the hole  112  formed in the bone. In this case the corner  105  is formed at about a 40° angle between the top  106  and the plow wall  104 . Further, abutment wall  103  and top  106  meet to form an angle of about 105°. The top has a length of about 4.6 millimeters and the abutment wall has a length of about 3.2 millimeters and plow wall  104  has a length of about 3.6 millimeters. These dimensions while specific to this embodimemt are proportional in all sizes of the suture anchor being used. That is, a larger suture anchor is made by merely proportionally increasing the dimensions while maintaining the angular relationship of the sides, walls and top in the same configuration. As can be seen in  FIGS. 21 and 22 , this embodiment can be supplied in a longer version which will require a deeper hole. 
   An alternative embodiment as shown in  FIG. 23  wherein the body  101 A is formed of a metal substance such as a titanium alloy. Preferably the alloy is Ti-6A1-4V alloy. The metal body  101 A has a similar suture opening  102  defined therein. An abutment wall  103  and plow wall  104  are provided as in the polymer version of the device and the plow wall  104  forms a corner  105  with the top in a similar fashion. The metal version is provided with a polymer shaft  107  having frangible portion  108  as is provided in the previous embodiment. The metal body  101 A is inserted into an injection mold and shaft  107  formed by injection molding the shaft into the metal body  101 A. Two intersecting openings are formed to provide a volume to be filled with polymer. The remainder of the metal device is substantially similar to the device of the previous description. 
   The shaft  107  of the metal version of the anchor may be made of any suitable biocompatible material such as medical grade polymers and may be a bioabsorbable material such as poly[L(−)lactide]. 
     FIGS. 24 and 25  show the rotational movement of the body  101  of the suture anchor upon implantation. This rotational movement provides torsional forces to the frangible portion  108  of the shaft  107  to promote the fracture of the shaft at the frangible location. 
   A novel insertion mechanism is shown in  FIG. 26 . The applicator  113  has a screw handle  114  having threads  115  formed thereon. The screw handle is adjusted by rotation against the spring force of spring  116 . Once positioned, the screw handle is locked in place using locking ring  117 , which is threaded down tightly against the back surface of the applicator  113 . A shaft  118  extends from the screw handle  114  along the length of the applicator  113 . The shaft has a wedged end  119  which is received substantially within a tubular portion  120  of the applicator. The device may be used in an open procedure. But, tubular portion  120  permits optional insertion of the applicator into a trocar for arthroscopic surgery. 
   The wedged end  119  is extended from within the tubular portion  120  by the rotation of screw handle  114  to permit extension of the shaft  118  and in particular, the wedge end  119  out of the tubular portion  120 . The shaft  107  of the suture anchor is inserted into the tubular portion  120  until the stop  110  seats firmly against the tubular portion  120  of the applicator  113 . At this point the screw handle is threaded in the opposite direction in order to draw the wedge end  119  within the tubular portion. The wedging or caming effect of the wedge end  119  firmly grasps the shaft  107  of the suture anchor and holds it within the device. 
   A finger  121  extends from the end of tubular portion  120  and seats along the top surface of the suture anchor in order to stabilize the body. This prevents premature rotation of the suture anchor and fracture of the frangible portion prior to complete insertion. The finger translates along the longitudinal portion of the tube in response to motion of trigger  122 . Upon use the device is inserted into a trocar in order to provide access arthroscopically to the surgical site. The suture anchor is placed into the previously bored bore hole and trigger  122  is manipulated. The manipulation of trigger  122  moves the finger  121  in the longitudinal direction. This forces rotation of the suture anchor body and promotes the fracture of the frangible portion of the shaft while holding the anchor in position. Simultaneously with manipulating the finger  121  the device is withdrawn thus completing the fracture of the frangible portion of the shaft. The previously threaded suture is then used to attach soft tissue according to known surgical procedures. 
   Referring now to  FIG. 27 , an alternative and preferred embodiment is shown. The body of the suture anchor is shaped as described above, however a mounting opening  130  is provided at one end of the body of the device. This opening is sized to receive the mounting end  131  of the insertion device shown in  FIGS. 28 and 29 . The insertion device  132  having mounting end  131  is comprised of an elongated shaft  133 . The shaft has two sections, a narrower distal section and a wider proximal section separated by a transitional section  134 . The transitional section  134  is conical in shape for reasons which will be described below in connection with the implantation procedure. A handle  135  is provided at a proximal end of the insertion device to facilitate gripping of the device during the implantation procedure. 
   In use, ( FIGS. 30 and 31 ) insertion end  131  is received within mounting opening  130  of the body of the suture anchor as shown in  FIGS. 28 and 29 . Mounting opening  130  is offset from the center line of the body of the suture anchor for reasons which will become apparent below. During the insertion procedure the suture anchor is inserted into a previously-formed bore hole. The insertion tool travels in a position off axis from the hole in the bone. Once the transition portion  134  reaches the top of the bore hole the transition surface forces the insertion tool towards the axis of the bore hole (i.e., the transition portion causes the tool to center). This causes the distal end of the tool to flex slightly and provides additional torque to the suture anchor assisting the plow edge in digging into the bone. A pair of slots  137  are provided to permit the protected passage of the suture out of the bore. Upon removal of the insertion tool, ( FIG. 32 ) the flex of the tool forces the plow edge of the suture anchor into the soft cancellous portion of the bone and the distal tip of the insertion tool slips out of the mounting opening  130  due to the upward force provided on the insertion tool. This provides an extra impetus to the insertion of the suture anchor and its final implantation and mounting. 
   In an alternative embodiment the insertion tool may be provided with a distal end  136  of a soft polymer material having therein a stiffening member such as a metal wire or polymer of more rigid material. Thus, a soft and manipulable insertion tool is provided having the resilience at the distal end to provide the insertion forces described above. The softer polymer insertion tool aids in producing a friction fit between the distal tip of the insertion tool and the mounting opening  130 . Thus, a more sure grip is provided between the tool and the body of the suture anchor. 
   In general the mounting opening  130  need not be cylindrical in shape. The mounting opening and distal tip of the insertion tool may be shaped so as to prevent rotation of the suture anchor about the tip. 
   A further embodiment developed for single piece polymer anchors is shown in  FIGS. 33 and 34 . The anchor has substantially the same shape as the anchors described above, however a protuberance  138  extends from the top surface of the wedge. This protuberance has formed therein the mounting opening  130  which receives the insertion tool described above as shown in  FIG. 34 . This protuberance provides an area for defining the mounting opening  130  such that the opening is not formed within the body of the wedge, possibly weakening the wedge. 
   Looking next at  FIGS. 35 and 36 , an alternative and preferred form of suture anchor assembly  200  is shown. Suture anchor assembly  200  generally comprises a suture anchor  300 , an installation tool  400  and a suture  500 . 
   Suture anchor  300  is shown in greater detail in  FIGS. 37–42 . Suture anchor  300  comprises a body  301  having a generally wedge-shaped configuration. Body  301  comprises a relatively narrow distal end  302  terminating in a rounded distal end surface  304 , and a relatively wide proximal end  306  terminating in a ledge surface  308  and a protuberance  310 . An abutment surface  312  extends along a longitudinal axis  314 , and a plow surface  316  extends along an intersecting axis  318 . Suture anchor  300  also comprises a pair of side surfaces  320 . As seen in the drawings, abutment surface  312  and plow surface  316  extend between the two side surfaces  320  and have a rounded configuration. Preferably this rounded configuration is formed so as to have the same radius of curvature as the bore hole into which the suture anchor is intended to be installed. Plow surface  316  and ledge surface  308  meet in a relatively sharp, well-defined biting edge  322 . 
   Protuberance  310  comprises a substantially flat proximal end surface  324 , a cam surface  326  extending between abutment surface  312  and proximal end surface  324  and a transition surface  328  extending between ledge surface  308  and proximal end surface  324 . As seen in the drawings, cam surface  326  is curved along its length. Cam surface  326  can be formed with a relatively constant radius of curvature throughout its length or, alternatively, cam surface  326  can be formed so as to have a changing radius of curvature when progressing distally to proximally along its length, for reasons which will be hereinafter discussed. By way of example, cam surface  326  can be formed so as to have a progressively increasing, or a progressively decreasing, radius of curvature when progressing distally to proximally along its length. 
   The suture anchor&#39;s ledge surface  308 , transition surface  328 , and proximal end surface  324  together form a complete boundary surface  329 . 
   A through-hole  330  extends across suture anchor  300 , from one side surface  320  to the other. Through-hole  330  is sized so as to have a diameter somewhat larger than the diameter of suture  500 , whereby suture  500  can be slipped through through-hole  330 , as will hereinafter be discussed in further detail. If desired, through-hole  330  can be sized so as to have a diameter somewhat larger than the combined diameters of two or more sutures, whereby several sutures can be simultaneously slipped through through-hole  330 . Preferably the entryways to through-hole  330  are rounded somewhat as shown at  332  so as to provide a smooth transition between side surfaces  320  and through-hole  330 . Such a configuration assists initial passage of suture  500  through through-hole  330 , as well as facilitating subsequent slipping motion of the suture relative to the suture anchor, e.g., such as when the suture anchor is deployed in a bone. In addition, such a configuration helps distribute the suture bearing stress more uniformly throughout the contour of through-hole  330 . 
   A blind hole  334  opens on the suture anchor&#39;s proximal end surface  324  and extends distally into the suture anchor along an axis  336 . Blind hole  334  serves as a mounting opening to receive the distal end of installation tool  400 , as will hereinafter be discussed. Blind hole  336  is disposed closer to abutment surface  312  than to biting edge  322 . Axis  336  is preferably set at a slightly intersecting angle relative to the longitudinal axis  314  of abutment surface  312 . Preferably the axis  336  of blind hole  334  is set at an angle of about 1° relative to the longitudinal axis  314  of abutment surface  312 , although this angle may be varied as preferred. Blind hole  334  comprises a bore  338  and a counterbore  340 . Bore  338  and counterbore  340  meet at an annular shoulder  342 . 
   Suture anchor  300  can be formed using any of the materials and/or techniques hereinabove discussed in connection with any of the anchors hereinabove discussed, or it can be formed using any other appropriate biocompatible material or technique. In one preferred form of the invention, suture anchor  300  is formed out of a bioabsorbable material such as polylactic acid (PLA). 
   Looking next at  FIGS. 35 and 43 , installation tool  400  generally comprises a main shaft  402 , a shaft tip  404 , a nose  406 , a shroud  408 , and a handle  410 . 
   Main shaft  402  is shown in greater detail in  FIGS. 44 and 45 . It comprises a substantially rigid elongated rod having a distal end  412  terminating in a distal end surface  414 , and a proximal end  416  terminating in a proximal end surface  418 . A blind hole  420  is formed in the distal end of the shaft, extending proximally from distal end surface  414 . Blind hole  420  is used to connect main shaft  402  to shaft tip  404 , as will hereinafter be discussed. A plurality of circumferentially-extending surface grooves  422  are formed in the proximal end of main shaft  402 , just distal to proximal end surface  418 . Surface grooves  422  provide the proximal end of main shaft  402  with a contour, and are used to connect main shaft  402  to handle  410 , as will also hereinafter be discussed. 
   Shaft tip  404  is shown in greater detail in  FIG. 46 . It comprises a relatively short rod having a distal end  424  and a proximal end  426 . Distal end  424  is formed so as to be somewhat flexible, and terminates in a threaded portion  428  comprising a plurality of screw threads  430 . The crests of screw threads  430  have substantially the same diameter as the adjoining portion  432  of shaft tip  404 , which diameter is slightly larger than the diameter of the suture anchor&#39;s bore  338  but slightly smaller than the diameter of the suture anchor&#39;s counterbore  340 , for reasons which will hereinafter be discussed. The total length of the shaft tip&#39;s threaded portion  428  is sized to be approximately the same as the distance between the suture anchor&#39;s shoulder  342  and the base of blind hole  334 . A circumferentially-extending surface groove  434  is formed in proximal end  426  of shaft tip  404 , just distal to proximal end surface  436 . A flange  438  is disposed intermediate shaft tip  404 . Flange  438  provides a distally-facing shoulder  440  and a proximally-facing shoulder  442 . 
   Shaft tip  404  can be formed out of any appropriate biocompatible material. By way of example, in one preferred form of the invention, shaft tip  404  is formed out of 17-4 PH stainless steel. 
   Nose  406  is shown in greater detail in  FIGS. 47–50 . Nose  406  comprises a generally frustoconical body  444  terminating in a distal end surface  446  and a proximal end surface  448 . An axial hole  450  opens on, and extends between, distal end surface  446  and proximal end surface  448 . A pair of posts  452  extend proximally out of the nose&#39;s proximal end surface  448 . A pair of diametrically-opposed surface grooves  454  extend between distal end surface  446  and proximal end surface  448  in the manner shown in the drawings. 
   Shroud  408  is used to retain suture  500  on installation tool  400  until that suture is to be deployed at the surgical site. Shroud  408  is shown in greater detail in  FIGS. 51–53 . It comprises a relatively flexible body terminating in a distal end surface  456  and a proximal end surface  458 . The shroud&#39;s body has a generally four-sided configuration, including a pair of diametrically-opposed sides  460 , forming ridge portions, and a pair of diametrically-opposed sides  462 . An elliptically-shaped internal opening  464  opens on, and extends between, distal end surface  456  and proximal end surface  458 . Internal opening  464  is arranged so that its long axis is aligned with the shroud&#39;s sides  460 , while its short axis is aligned with the shroud&#39;s sides  462 . Internal opening  464  is sized so the installation tool&#39;s main shaft  402  can be received within internal opening  464 , with main shaft  402  making a close sliding fit across the internal opening&#39;s short axis, as will hereinafter be discussed in further detail. 
   Each of the shroud&#39;s sides  462  includes a longitudinally-extending channel  466 . Each of the channels  466  communicates with the region external to the shroud via a corresponding longitudinally-extending slot  468 . Channels  466  are preferably sized so as to have a diameter approximately the same as the diameter of suture  500 , while slots  468  are sized so as to have a width somewhat less than the diameter of suture  500 . Each of the shroud&#39;s sides  462  is recessed or scalloped away (as at  470 ) for a short length near the proximal end of the shroud so as to open the full diameter of each of the channels  466  to the region external to the shroud. 
   Shroud  408  may be formed out of any appropriate material, e.g., it may be formed out of a soft compliant polymer such as nylon or polypropylene. 
   It is to be appreciated that, on account of the foregoing construction, (i) by pressing on the shroud&#39;s opposing ridge portions (i.e., sides  460 ), slots  468  can be made to widen so as to permit suture  500  to be laid down in channels  466 , and (ii) by relaxing pressure on the shroud&#39;s opposing sides  460 , slots  468  can be made to return to their normal, narrower width so as to retain suture  500  in channels  466 . It is also to be appreciated that, inasmuch as shroud  408  is formed out of a relatively flexible material, any suture  500  disposed in channels  466  can be pulled free of the channels with an appropriate withdrawal force, whereby the suture can be freed from the installation tool. In particular, suture  500  can be freed from installation tool  400  by pulling the suture in an axial direction relative to the installation tool, whereby the suture will be drawn out of the ends of channels  466 ; or suture  500  can be freed from installation tool  400  by pulling the suture at an angle to the installation tool, whereby the suture will be peeled out of channels  466  via a deformation of slots  468 . 
   Looking next at  FIGS. 35 ,  43  and  54 – 57 , handle  410  is preferably formed out of two halves  410 A and  410 B which are attached together so as to form the complete handle  410 . Handle  410  comprises a contoured recess  472  (which is in turn formed out of contoured hemi-recesses  472 A and  472 B) which is configured so as to make a tight fit about the correspondingly contoured proximal end of main shaft  402 , whereby handle  410  can be securely mounted to main shaft  402  and thus used to manipulate installation tool  400 . The exterior configuration of handle  410  includes a first protrusion  474 , a second protrusion  476  and a third protrusion  478 . First protrusion  474  is aligned with the installation tool&#39;s main shaft  402  along an axis  480  ( FIG. 35 ). Second and third protrusions  476  and  478  are aligned with one another along another axis  482 . Axis  482  is set an inclined angle relative to axis  480 . Preferably, axis  482  is set at an angle of about 70°  0  (as measured along the arc  484  in  FIG. 35 ), although angles of about 45° to about 85° are also appropriate. Thus, first, second, and third protrusions  474 ,  476  and  478  form an inclined “T” configuration. Second and third protrusions  476  and  478  are sized so that they will together form a natural handle for a user, e.g., so that the user&#39;s thumb and forefinger can comfortably engage second protrusion  476  while the user&#39;s remaining fingers engage third protrusion  478 . As a result of the foregoing construction, the user will be able to comfortably grasp the installation tool&#39;s handle  410  and, with the pad of the hand engaging the handle&#39;s proximal surface  486 , thereafter thrust the installation tool distally along the axis  480 , as will hereinafter be discussed. 
   Suture anchor assembly  200  is intended to be assembled as follows. First, installation tool  400  is assembled, then suture anchor  300  is attached to the assembled installation tool, and finally suture  500  is attached to suture anchor  300  and installation tool  400 . 
   Installation tool  400  is intended to be assembled as follows. 
   First, main shaft  402 , shaft tip  404  and nose  406  are assembled into a subassembly such as shown in  FIG. 58 . This is done by mounting nose  406  on shaft tip  404  by inserting the proximal end of the shaft tip through axial hole  450  of the nose until the shaft tip&#39;s proximally-facing shoulder  442  engages the nose&#39;s distal end surface  446 , and then mounting shaft tip  404  on main shaft  402  by inserting the proximal end of the shaft tip in the main shaft&#39;s blind hole  420  until the main shaft&#39;s distal end surface  414  engages the nose&#39;s proximal end surface  448 . The proximal end of shaft tip  404  is made fast in main shaft  402  by crimping or by other means well known in the art. As a result of the foregoing construction, nose  406  is effectively captured between the shaft tip&#39;s proximally-facing shoulder  442  and the main shaft&#39;s distal end surface  414 . 
   Next, shroud  408  is loaded onto the aforementioned subassembly. This is done by first aligning main shaft  402  with the shroud&#39;s internal opening  464 , with the two posts  452  of the nose being aligned with the long axis of the elliptically-shaped opening  464 . Then the proximal end of main shaft  402  is passed through the shroud&#39;s internal opening  464  until the two posts  452  of the nose enter the shroud&#39;s internal opening  464  and the shroud&#39;s distal end surface  456  seats firmly against the nose&#39;s proximal end surface  448 . At this point each of the two surface grooves  454  of nose  406  will be aligned with one of the channels  466  of shroud  408 , with main shaft  402  making a close sliding fit across the short axis of the shroud&#39;s internal axis  464 . 
   Next, handle  410  is attached to the proximal end of main shaft  402 . This is done by fitting the proximal end of main shaft  402  in either hemi-recess  472 A of handle half  410 A or hemi-recess  472 B of handle half  410 B, and then placing the corresponding complementary second handle half (i.e., either handle half  410 B or handle half  410 A, respectively) in place, and finally making the two handle halves fast to one another in ways well known in the art (e.g., by ultrasonic welding), whereby they will be securely attached to the proximal end of main shaft  402 . It is to be appreciated that when handle  410  is so mounted to main shaft  402 , the distal end of the handle&#39;s first protrusion  474  will substantially engage the shroud&#39;s proximal end surface  458 . It is also to be appreciated that handle  410  is mounted to main shaft  402  such that the plane extending between the two handle halves  410 A and  410 B will be aligned with the major axis of the shroud&#39;s internal opening  464 , with one of the shroud&#39;s channels  466  being aligned with each handle half, and with the one of the shroud&#39;s recessed or scalloped sections  470  being aligned with, and residing adjacent to, each handle half. 
   It is to be appreciated that inasmuch as main shaft  402  and shaft tip  404  are formed out of two separate elements which are securely attached together, each element can be designed for its own particular requirements. In particular, main shaft  402  can be designed so as to provide the desired rigidity, whereas shaft tip  404  can be designed so as to provide the desired flexibility; yet the two elements are securely attached to one another so as to together operate as the desired unit. 
   Suture anchor  300  is attached to the assembled installation tool  400  as follows. First, suture anchor  300  and installation tool  400  are oriented so that the distal end of shaft tip  404  is aligned with the suture anchor&#39;s blind hole  334 . Then suture anchor  300  and installation tool  400  are brought together as they are simultaneously turned relative to one another, whereby the suture anchor will be mounted on the distal end of the installation tool&#39;s shaft tip  404 , with the threaded portion  428  of shaft tip  404  being threadedly mounted in the suture anchor&#39;s bore  338 , and with the immediately-proximal portion  432  of the shaft tip being received in the suture anchor&#39;s counterbore  340 . It is to be appreciated that due to the relative sizing of the suture anchor&#39;s blind hole  334  (see  FIG. 59 ) and the shaft tip&#39;s distal end  424 , the shaft tip&#39;s threaded portion  428  will make a threaded engagement with the suture anchor within bore  338 , but the shaft tip&#39;s immediately-proximal portion  432  will not be secured to the suture anchor within counterbore  340 . 
   Suture anchor  300  and installation tool  400  are arranged so as to have a specific orientation relative to one another, i.e., so that the suture anchor&#39;s two side surfaces  320  extend parallel to the plane extending between the two handle halves  410 A and  410 B, with the suture anchor&#39;s abutment surface  312  being aligned with the handle&#39;s second protrusion  476  and the suture anchor&#39;s plow surface  316  being aligned with the handle&#39;s third protrusion  478  (see  FIGS. 35 ,  36  and  60 ). It is to be appreciated that, on account of the foregoing arrangement, the user will always know the orientation of suture anchor  300  simply by knowing the orientation of the installation tool&#39;s handle  410 . This can be an important feature in certain types of surgery where the suture anchor may have to be set with a particular orientation and the user&#39;s view of the suture anchor itself may be restricted. 
   Next, suture  500  is attached to suture anchor  300  and installation tool  400 . This is done by passing suture  500  through the suture anchor&#39;s through-hole  330  and then positioning the suture within the shroud&#39;s longitudinally-extending channels  466 . In this respect it will be appreciated that suture  500  can be easily positioned in channels  466  by first pressing on the shroud&#39;s opposing side surfaces  460  so as to open slots  468 , then laying down suture  500  within the opened channels  466 , and then releasing the shroud&#39;s opposing side surfaces  460  so as to releasably capture the suture within channels  466 . The proximal ends of suture  500  are arranged so that they exit the shroud adjacent to recessed or scalloped portions  470 , where they rest free adjacent to handle  410  (see  FIGS. 36 ,  53  and  61 ). 
   Suture anchor assembly  200  is intended to be used as follows. 
   First, suture anchor assembly  200  is picked up by the user so that the user&#39;s thumb and forefinger engage the handle&#39;s second protrusion  476  and the user&#39;s remaining fingers engage the handle&#39;s third protrusion  478 , and so that the handle&#39;s proximal surface  486  sits against the heel of the user&#39;s hand (see  FIG. 62 ). It is to be appreciated that when the suture anchor assembly is held in this manner, the apparatus will be ready to drivingly insert the suture anchor in a bore hole formed in a bone. Furthermore, in view of the fact that the suture anchor is mounted to the installation tool with a predetermined orientation, the user will always know the relative positioning of the suture anchor&#39;s abutment surface  312 , its plow surface  316 , and its sharp, well-defined biting edge  322 , even if the suture anchor itself is not directly visible to the user. 
   Next, the user uses installation tool  400  to drive suture anchor  300  into a bore hole. This is done by aligning suture anchor  300  with a bore hole  600  formed in a bone  601  ( FIG. 63 ) and then pushing the suture anchor into the bone hole. As this occurs, the suture anchor&#39;s plow surface  316  will first tend to engage rim  603  of bore hole  600 , causing the distal end of shaft tip  404  to flex as the suture anchor pivots to enter the bore hole. Further downward pressure on the installation tool&#39;s handle  410  causes the distal end of the shaft tip to flex even further as the suture anchor&#39;s plow surface  316  engages, and then rides along, wall  602  of the bore hole, with the suture anchor&#39;s cam surface  326  being slightly spaced from, or insignificantly in contact with, the bore hole&#39;s opposing wall  606  (see  FIG. 64 ). Significantly, such flexing of the distal end of shaft tip  404  does not significantly undermine the attachment of suture anchor  300  to installation tool  400 , since only the distalmost portion of the shaft tip (i.e., the threaded portion  428 ) is actually secured to the suture anchor, with the shaft tip&#39;s immediately-proximal portion  432  being free to flex slightly within the suture anchor&#39;s counterbore  340  without damaging the suture anchor. This is true even where suture anchor  300  may be formed out of a non-metallic material, e.g., a plastic or absorbable material. 
   The user pushes suture anchor  300  downward into bore hole  600  until the desired depth is reached. Such downward pressure keeps the suture anchor&#39;s plow surface  316  in engagement with the bore hole&#39;s wall  602 . Preferably installation tool  400  is sized so that nose  406  engages the top surface  604  of bone  601  when the desired depth is reached. 
   Next, the user withdraws installation tool  400  from bore hole  600 . As downward pressure on installation tool  400  is released (to be replaced by opposite upward pressure during tool withdrawal), the flexed shaft tip  404  tries to straighten itself, causing the suture anchor&#39;s sharp, well-defined biting edge  322  to press into wall  602 , and causing the suture anchor to pivot slightly in the bore hole so that the suture anchor&#39;s cam surface  326  securely engages wall  606  of the bore hole. As the user retract&#39;s installation tool  400  from bore hole  600 , rearward movement of installation tool  400  causes progressively more distal portions of the suture anchor&#39;s cam surface  326  to come into engagement with wall  606  of the bore hole. Since cam surface  326  is arranged to cam the suture anchor laterally, such engagement of cam surface  326  with bone wall  606  causes the anchor&#39;s sharp, well-defined biting edge  322  to be driven progressively further and further into wall  602  of the bore hole, until the suture anchor&#39;s abutment surface  312  rests against wall  606  ( FIG. 65 ). As installation tool  400  is pulled further back, the installation tool eventually breaks free from the lodged suture anchor. The installation tool is then withdrawn from the surgical site. 
   It should be appreciated that the presence of cam surface  326  significantly enhances the ability of suture anchor  300  to set in bone  601 , since the cam surface provides a force on the suture anchor&#39;s edge surface  322  which is approximately normal to the bore hole&#39;s wall  602 . This force drives the suture anchor&#39;s edge surface  322  into wall  602 , ensuring that the suture anchor will be reliably set. This is true even where bone  601  is relatively hard (e.g., cortical bone) and the suture anchor is made out of a non-metallic material, e.g., plastic or a bioabsorbable material. 
   By changing the geometry of cam surface  326 , the setting characteristics of suture anchor  300  can be adjusted. 
   It should also be appreciated that the nature of the attachment of suture anchor  300  to installation tool  400  is important. In particular, the suture anchor must be attached to the installation tool securely enough to cause the suture anchor to turn in the aforementioned camming action, yet release at the appropriate time so as to leave the suture anchor in the bone as the installation tool is withdrawn. Thus it is desirable that the connection between suture anchor  300  and installation tool  400  be well defined at the time of manufacture, and remain intact up until the time that the installation tool breaks free from the anchor. In particular, it is important that this connection not be undermined while the distal end of the installation tool flexes in the bore hole. It has been found that such a reliable connection can be established by providing the distal end of the shaft tip with a threaded portion  428  and an immediately-proximal smooth portion  432 , and providing suture anchor  300  with a bore  338  and a counterbore  340 , where the shaft tip&#39;s threaded portion  428  makes a threaded engagement with the suture anchor within bore  338 , but the shaft tip&#39;s immediately-proximal portion  432  is not secured to the suture anchor within counterbore  340 . This permits the necessary flexing of the shaft tip to occur without undermining the connection between the installation tool and the suture anchor, even where the suture anchor is formed out of a non-metallic material, e.g., a plastic or absorbable material. 
   It is to be appreciated that as installation tool  400  separates from the deployed anchor  300 , suture  500  can simultaneously slide along the inner surfaces of the shroud&#39;s channels  466 , so as to permit the two members to separate. Depending on the length of suture  500  and the degree of separation imposed, suture  500  may or may not be fully removed from installation tool  400  during anchor deployment. To the extent that some of suture  500  remains attached to installation tool  400  after the installation tool has been withdrawn, the installation tool may be placed on a surgical drape adjacent to the surgical site until the suture  500  is to be completely removed from the installation tool. At that point the remaining suture may be pulled free of the installation tool. 
   For many procedures, retaining a portion of suture  500  in installation tool  400  until needed can be helpful for effective suture management. For example, where an arthroscopic procedure involves more than one suture anchor, the paired suture ends of several suture anchors might emanate from a single cannula opening. By way of example, an arthroscopic Bankhart procedure could involve four or even six suture lengths emanating from a single cannula opening. In such a situation, retaining suture lengths in the installation tool can help keep the suture lengths more easily identifiable for the surgeon. 
   Additionally, and/or alternatively, to help improve suture management, it may be desired to mark various suture lengths. For example, each suture length could be distinctively color-coded, or distinctively pattern-coded. U.S. Pat. No. 3,949,755 issued Apr. 13, 1976 to Vauquois teaches the provision of contrasting shades on suture, which patent is hereby incorporated herein by reference. 
   It is also possible to modify the suture anchor  300  described above. 
   For example, in the suture anchor  300  described above, the suture anchor&#39;s through-hole  330  is preferably sized so as to slidably receive a single strand of suture. However, if desired, the suture anchor&#39;s through-hole  330  could be sized so as to slidably receive multiple stands of suture simultaneously. Of course, if such a construction were used, the shroud&#39;s channels  466  should be correspondingly enlarged so as to accommodate the additional suture lengths provided, or some other provision should be made to manage the additional suture ends present with such a construction. 
   Furthermore, with the suture anchor  300  described above, the suture anchor&#39;s through-hole  330  is formed so as to have a substantially round configuration. However, the suture anchor&#39;s through-hole can also be formed with an elliptical configuration, such as the through-hole  330 A provided in the suture anchor  300 A shown in  FIGS. 66–68 . By forming the suture anchor&#39;s through-hole with an elliptical configuration, stresses from the suture can be directed to specific portions of the suture anchor. In particular, these suture stresses can be directed to more robust portions of the suture anchor, thereby enabling the suture anchor to carry larger loads. This feature can be particularly useful where the suture anchor is formed out of a non-metallic material, e.g. a plastic or bioabsorbable material. In addition, by forming the suture anchor&#39;s through-hole with an elliptical configuration, subsequent proximal pulling of the suture can also help to further set the suture anchor with a desired orientation within the bone. 
   Also, with the suture anchor  300  described above, the suture anchor is configured so as to have substantially planar side surfaces  320 . As a result, the anchor must be formed thin enough so that the suture lengths emanating from the anchor can pass alongside the suture anchor within the bore hole (see  FIG. 69 ). This is particularly true where it is desired to slide suture  500  relative to suture anchor  300  when the suture anchor is set in a bone hole. However, in many situations it can be advantageous to form the suture anchor with the thickest possible configuration, with the sides of the suture anchor having a rounded outer surface, e.g., such as the side surfaces  320 B provided for the suture anchor  300 B shown in  FIGS. 70 and 71 . In this situation, a pathway  344  must be provided to permit suture  500  to pass from the suture anchor&#39;s through-hole  330  to the exterior of the bone. In this respect it should also be appreciated that inasmuch as the suture anchor must rotate within the bone, the pathways  344  should be formed with a configuration which broadens toward the proximal end of the anchor, in the manner schematically illustrated in  FIG. 70 . Such a construction permits the necessary anchor rotation to occur without causing the suture to come into abrasive engagement with the side walls of the bore hole. 
   Also, it is possible to omit the suture anchor&#39;s through-hole  330  and attach the suture directly to the anchor. Thus, for example, a suture anchor  300 C is shown in  FIG. 72  where the suture  500  is molded or fused directly into the side  320 C of the body of the anchor. Alternatively, and looking now at  FIG. 73 , the suture  500  could enter the proximal end surface  324 D of a suture anchor  300 D and then be internally fused to the interior of the suture anchor. This could be done with a single suture strand, or with a pair of independent suture strands, or with a looped suture strand where the loop is fused within the interior of the body. 
   It is also possible to attach a suture to the suture anchor by forming a longitudinal hole through the suture anchor, passing the suture through that longitudinal hole, and then knotting the suture at the distal end of the suture anchor so as to prevent the suture from being withdrawn proximally through the suture anchor. Alternatively, an enlargement of some other sort could be positioned at the distal end of the suture to prevent suture withdrawal. Thus, for example, a suture anchor  300 E is shown in  FIG. 74 , wherein suture  500  passes through a pair of longitudinal holes  346  opening on proximal end surface  324 D, and then are knotted at a knot  502  near the distal end of the anchor. If desired, a recess or cutaway  348  can be provided near the distal end of the anchor to accommodate knot  502 . Alternatively, a single suture strand  500  could be used, with the suture strand passing down one longitudinal hole  346  and back up the other longitudinal hole, whereby the use of the knot  502  could be eliminated. 
   Thus, the invention has been described with reference to the attached drawings. It is easily understood by one of ordinary skill in the art that changes may be made to the embodiments described herein without exceeding the spirit or scope of the attached claims.