Versions of the present invention relate to restoring the anatomy of fractured bone and, more particularly, to restoring the anatomy of fractured bone with an inflatable device.
Increasingly, surgeons are using minimally invasive surgical techniques for the treatment of a wide variety of medical conditions. Such techniques typically involve the insertion of a surgical device through a natural body orifice or through a relatively small incision using a tube or cannula. In contrast, conventional surgical techniques typically involve a significantly larger incision and are, therefore, sometimes referred to as open surgery. Thus, as compared with conventional techniques, minimally invasive surgical techniques offer the advantages of minimizing trauma to healthy tissue, minimizing blood loss, reducing the risk of complications such as infection, and reducing recovery time. Further, certain minimally invasive surgical techniques may be performed under local anesthesia or even, in some cases, without anesthesia, and therefore enable surgeons to treat patients who would not tolerate the general anesthesia required by conventional techniques.
Surgical procedures often require the formation of a cavity within either soft or hard tissue, including bone. Tissue cavities are formed for a wide variety of reasons, such as for the removal of diseased tissue, for harvesting tissue in connection with a biopsy or autogenous transplant, and for implant fixation. To achieve the benefits associated with minimally invasive techniques, tissue cavities are generally formed by creating only a relatively small access opening in the target tissue. An instrument or device may then be inserted through the opening and used to form a hollow cavity that is significantly larger than the access opening.
One surgical application utilizing the formation of a cavity within tissue is the surgical treatment and prevention of skeletal fractures associated with osteoporosis, which is a metabolic disease characterized by a decrease in bone mass and strength.
The disease frequently leads to skeletal fractures under light to moderate trauma and, in its advanced state, can lead to fractures under normal physiologic loading conditions. It is estimated that osteoporosis affects approximately 15-20 million people in the United States and that approximately 1.3 million new fractures each year are associated with osteoporosis, with the most common fracture sites being the hip, wrist, and vertebrae.
An emerging prophylactic treatment for osteoporosis, trauma, or the like involves replacing weakened bone with a stronger synthetic bone substitute using minimally invasive surgical procedures. The weakened bone is first surgically removed from the affected site, thereby forming a cavity. The cavity is then filled with an injectable synthetic bone substitute and allowed to harden. The synthetic bone substitute provides structural reinforcement and thus lessens the risk of fracture of the affected bone. Without the availability of minimally invasive surgical procedures the prophylactic fixation of osteoporosis-weakened bone in this manner would not be practical because of the increased morbidity, blood loss, and risk of complications associated with conventional procedures. Moreover, minimally invasive techniques tend to preserve more of the remaining structural integrity of the bone because they minimize surgical trauma to healthy tissue.
Other less common conditions in which structural reinforcement of bone may be appropriate include bone cancer and avascular necrosis. Surgical treatment for each of these conditions can involve removal of the diseased tissue by creating a tissue cavity and filling the cavity with a stronger synthetic bone substitute to provide structural reinforcement to the affected bone.
Medical balloons are commonly known for dilating and unblocking arteries that feed the heart (percutaneous translumenal coronary angioplasty) and for arteries other than the coronary arteries (noncoronary percutaneous translumenal angioplasty). In angioplasty, the balloon is tightly wrapped around a catheter shaft to minimize its profile, and is inserted through the skin and into the narrowed section of the artery. The balloon is inflated, typically, by saline or a radiopaque solution, which is forced into the balloon through a syringe. Conversely, for retraction, a vacuum is pulled through the balloon to collapse it.
Medical balloons also have been used for the treatment of bone fractures. One such device is disclosed in U.S. Pat. No. 5,423,850 to Berger, which teaches a method and an assembly for setting a fractured tubular bone using a balloon catheter. The balloon is inserted far away from the fracture site through an incision in the bone, and guide wires are used to transport the uninflated balloon through the medullary canal and past the fracture site for deployment. The inflated balloon is held securely in place by the positive pressure applied to the intramedullary walls of the bone. Once the balloon is deployed, the attached catheter tube is tensioned with a calibrated force measuring device. The tightening of the catheter with the fixed balloon in place aligns the fracture and compresses the proximal and distal portions of the fractured bone together. The tensioned catheter is then secured to the bone at the insertion site with a screw or similar fixating device.