There are about 500,000 fractures of the tibia and fibula, 200,000 metacarpal fractures and over 400,000 distal radial fractures in the United States each year. In many cases the bones are immobilized by placing a cast on the fractured limb. However, casts often must immobilize a substantial length of the limb, can be heavy, inconvenient and limit the use of the limb, including significantly limiting the mobility of the subject. Additionally, there is a risk of non-union of the fractured ends, resulting in a failure of the fractured ends to unite. Non-unions may require additional operations to promote fracture healing. In addition to the risk of general anesthesia and early post-operative venous thromboembolism complications in patients who require re-operation face additional rehabilitation and time off from work.
Another means for fixation of long bone fragments includes the use of Kirschner wires (K-wires) drilled into the bone fragments and held in place by an external fixation device. However, external fixation devices may not be practical in all situations, as they may interfere with some functions. Additionally, because K-Wires pass through the skin, extended presence of conventional K-Wires may form a potential passage for bacteria and cause infection. Additionally, conventional K-Wires can migrate, causing a loss of fixation of the bone fragments.
Still another means for fixation of long bone fragments includes the insertion of an intramedullary (IM) nail into the lumen, or medullary cavity, of the long bone. The IM nail spans the fracture and is secured to the bone on either side by screws through the bone. IM nails are typically manufactured from a durable metal material and may be left in the bone after healing. In some instances, however, surgical removal of a durable IM nail is required, again exposing a subject to the risks of general anesthesia, venous thromboembolism, rehabilitation and time off from work. Additionally, present IM nails do not fill up the entire width of the lumen in the bone, potentially allowing the fracture to unite in a displaced, off-set or crooked manner, resulting in improper healing of the fracture. Accordingly, there exists a need for an improved IM nail in the form of an orthopedic fastener that is biodegradable and fills the lumen to prevent off-set healing of the fracture.