Various intramedullary nails, particularly for use in repair of fractures of the femur, are known in the prior art.
Fractures of the femur can occur in any part of the femur from the femoral neck to the supracondylar region. Such fractures, in the past, have been particularly vexatious because of the required extended periods of time that the patient must be at least partly immobilized during the healing of such fractures. There is also a significant recovery period due to such extended immobilization.
In contrast, intrarmedullary nailing of femoral fractures permits the patient to apply weight to the involved leg within a day or two after surgery. Correspondingly, the technique of intramedullary nailing has found particular application in fractures of the femur.
Nails of different length are required for femoral nailing, depending on the location of the fracture and length of the femur of the patient. Nails of different diameters are also required to permit selection of a nail to fit the medullary canal of the patient after the usual procedure of reaming this canal, since a loose fit will not hold the fracture, and a very tight fit risks jamming in the bony tube. In the past, different nails and nailing arrangements have been used to repair fractures in different portions of the femur. This has required the surgeon to have available each of the different types of nails in each of the various required lengths and diameters, or delay operating until the proper nail or selection of nails can be obtained. Of further significance has been the need for the surgeon to acquire expertise in the use of and installation of these different types of prior art nails to repair fractures in different parts of the femur.
The use of such nails to surgically repair the femur requires reaming of the medullary canal to provide an appropriate opening to receive the nail. Pre-operative roentgenograms of the fractured femur and both adjacent joints are taken in two planes, usually at the same distance from the femur in an effort to determine the extent of damage and to provide a gauge for use in selection of an appropriate nail. It is however, desirable to have several nails of slightly different diameter and of different lengths available, since such gauging may not be completely accurate.
In the past, a femoral nail in the form of a slotted steel tube, sometimes referred to as the Kuntscher nail was driven into the medullary canal of the femur to repair fractures. The theory behind the Kuntscher intramedullary nail is that the slotted tube is transversely elastic, and is driven into a slightly smaller medullary canal thereby permitting the nail to lock by expansion in the medullary canal. It is, however, this transverse elasticity which causes difficulties in applications requiring a transverse screw, since the nail can also distort torsionally during insertion and the preformed screw or cross-nail receiving openings in the walls of the nail, particularly at the distal end, are often difficult to precisely locate. It is to be appreciated that the surgeon often works "blind" during the operation, since X-ray exposure must be maintained at a minimum, and the location of screw or transverse pin receiving openings in a twisted nail are often difficult to gauge even with several roentenograms. Should the location and angular disposition of the screw receiving openings in the inserted nail be misjudged or out of alignment with each other, insertion of the transverse screw becomes difficult and time consuming.
In addition to the Kuntscher nail, a number of other nails and techniques have been proposed for pinning or nailing fractures in various portions of the femur. As indicated above, however, in the past, different types of nails have been used for nailing of different portions of the femur. For example, where the fracture is in the femoral neck, one type of nail was used, and a different nail was used for a fracture of the intertrochanteric region, and yet a third type of nail was required for fractures in the distal femur region. As also indicated above, this required not only a different nail for the different fractures, but also required the surgeon to attain expertise in the use of each different nail.
Further, it was, in the past, necessary to have left and right nails for use in the left and right femoral neck fractures.
In summary, the available prior art nails have simply not been wholly satisfactory for repair of fractures of the femur.
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USPTO Backgrounds