As the treatment of injuries to joints and soft tissue has progressed in the orthopedic 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, it is 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 orthopedic procedure for reattaching soft tissue to bone is performed by initially drilling holes or tunnels at predetermined locations through a bone in the vicinity of a joint.  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.  The bone tunnels, which are open to various body fluids and infectious agents, may become infected or break.  Other known complications may arise including a longer bone-healing period, etc.  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 may be anatomically impossible or at least 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. 
Another conventional orthopaedic procedure is that of repairing torn or injured soft tissues such as menisci in the knee.  Various kinds of devices has been designed to facilitate insertion of sutures through both sides of the meniscus, but they have been fraught with technical difficulty and some complications such as injury to the blood vessels and nerves.  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 or bone to bone.  A suture anchor is an orthopedic, medical device which is typically implanted into a cavity drilled into a bone.  These devices are also referred to as bone anchors.  In use, the suture anchor is emplaced within the bone and a suture is attached to a portion thereof which is in turn attached to the soft tissue or bone to keep the soft tissue or bone in place against the anchoring bone, for healing purposes.  The tension exerted upon the suture, resisted on one end by the emplaced suture anchor, maintains contact between bone and soft tissue.  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 and into the inner cancellous layer.  The suture anchor may be engaged in the bore hole by a variety of mechanisms including friction fit, barbs which are forced into the cancellous layer of bone, etc.  Suture anchors are known to have many advantages including reduced bone trauma, simplified application procedures, and decreased likelihood of suture failure.  Suture anchors may be used in the Bankart shoulder reconstruction for repairing a lesion of the labrum of the glenoid ligament and may also be used in various orthopedic surgical procedures including those involving rotator cuff repair, ankle, elbow, foot, knee, hand and wrist repair, hip replacement, knee replacement and other bony procedures, such as sternotomy. 
Suture anchors typically have a hole or opening for receiving a suture.  The suture extends out from the bore hole and is used to attach soft tissue.  The suture anchors presently described in the art may be made of absolute materials that 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.  Moreover, when an absorbable suture anchor is fully absorbed it will no longer be present as a foreign body. 
Although suture anchors for attaching soft tissue to bone are available for use by the orthopedic surgeon, there is a constant need in this art for novel suture anchors having improved performance characteristics, such as ease of insertion and greater resistance to "pull-out".