Joint injuries can result in the complete or partial detachment of ligaments, tendons and soft tissues from bone. Tissue detachment may occur in many ways, e.g., as the result of an accident such as a fall, overexertion during a work related activity, during the course of an athletic event, or in any one of many other situations and/or activities. These types of injuries are generally the result of excess stress or extraordinary forces being placed upon the tissues.
In the case of a partial detachment, commonly referred to under the general term “sprain,” the injury frequently heals without medical intervention, the patient rests, and care is taken not to expose the injury to undue strenuous activities during the healing process. If, however, the ligament or tendon is completely detached from its attachment site on an associated bone or bones, or if it is severed as the result of a traumatic injury, surgical intervention may be necessary to restore full function to the injured joint. Numerous devices are currently available to re-attach soft tissue to bone. Examples of such currently available devices include screws, staples, suture anchors, and tacks.
Such procedures involve the re-attachment of the detached tissue using “traditional” attachment devices such as staples, sutures, and bone screws. Such traditional attachment devices have also been used to attach tendon or ligament grafts (often formed from autologous tissue harvested from elsewhere in the body) to the desired bone or bones. In soft tissue re-attachment procedures utilizing interference screws, the detached soft tissue is typically moved back into its original position over the bone. Then the screw is screwed through the soft tissue and into the bone, with the shank and head of the screw holding the soft tissue to the bone. Similarly, in soft tissue re-attachment procedures utilizing staples, the detached soft tissue is typically moved back into its original position over the bone. Then the staple is driven through the soft tissue and into the bone, with the legs and bridge of the staple holding the soft tissue to the bone. Although traditional attachment devices can hold soft tissue to bone, the devices can crack, break, or otherwise fail during or after implantation, which can delay healing and/or injure the patient. Additionally, the traditional attachment devices can damage the soft tissue and/or bone by being driven therein, which can cause undesirable effects, such as infection, delayed healing, and/or additional surgery to repair the device, the tissue, and/or the bone.
In procedures where a graft is held to the bone using an interference screw, such as ACL reconstruction, a bone tunnel is created that is just large enough to fit the graft. The graft is either pulled or pushed into the bone tunnel using various methods, and the interference screw is inserted into the bone tunnel. The interference fit of the shank and the head of the screw hold the graft against the bone inside the bone tunnel with a very high degree of interference. However, failure can occur due to screw breakage, bone or graft damage, and high torque requirements. In another approach, the graft can be pulled through a bone tunnel and suspended, e.g., with sutures or cords, from the other side of the bone. However, this approach does not provide aperture fixation and can lead to tunnel widening due to abrasion from the sutures or cords during movement.
Accordingly, there remains a need for improved methods and devices for anchoring a graft to bone.