This invention relates generally to orthopedic instruments and, more particularly, to an orthopedic instrument which is especially well suited for use with an intramedullary femoral nail.
The use of nailing techniques for the treatment of fractures of the femur is well known. In cases of severe injury, fractures of the femoral neck often accompany fractures of the femoral shaft. For this reason, a number of intramedullary nails provide one or more openings in the proximal end of the nail for receiving a fastener, such as a bone screw, which extends along a line which passes through the lateral cortex of the femur, through the femoral neck, and into the subchondral region of the femoral head. An example of one such nail is shown in U.S. Pat. No. 4,622,959.
When using a nail and related fasteners of the types described in the above-referenced patent to reduce fractures of the femur and the femoral neck, it is necessary to drill one or more holes from the side of the femur through the neck and into the femoral head, along the line of the screw-receiving opening(s) formed in the proximal end of the nail. Since proper drill alignment with the opening(s) in the inserted nail can be difficult to achieve, a number of jigs and fixtures have been devised to accomplish this end. Two such instruments are shown in FIGS. 1 and 2 of this specification, and are described in detail below.
When using devices such as those illustrated in FIGS. 1 and 2 to locate and drill holes in the femur, it is desirable that the guide arm of the instrument, which normally extends downwardly and substantially parallel to the femur, be positioned as closely as possible to the soft tissues covering the femur. Instruments of the type shown in FIG. 1, in which the lateral distance between the guide arm and femur are fixed, do not allow close positioning of the guide arm to the femur, since the lateral distance between the femur and guide arm must be selected to accommodate relatively thick soft tissues typically found in obese patients. Instruments of the type shown in FIG. 2 provide for some degree of lateral adjustment, but fail to provide optimal results throughout the complete range of patient types and body sizes. Accordingly, there exists a need for an orthopedic instrument of the above-described type in which the guide arm is adjustable to accommodate the full range of patient body types. It is an object of this invention to provide such an instrument.
This and other objects are attained in an orthopedic instrument which is especially well suited for use with an intramedullary femoral nail having one or more openings in its proximal end for receiving one or more fasteners. At least one of these openings extends upwardly along a target line which passes through the lateral cortex of the femur, through the femoral neck, and into the subchondral region of the femoral head. The preferred embodiment of the orthopedic instrument of the present invention includes means for securing the instrument to the proximal end of the nail, means for circumferentially and axially aligning the instrument with the nail, a handle attached to the means for securing the instrument to the nail and extending downwardly along a line substantially parallel to the target line, and a guide arm assembly which is adjustably and movably mounted on the handle means. The guide arm assembly extends through the target line and is provided with at least one opening extending coaxially with the target line for receiving orthopedic accessories, such as drills, reaming devices, guide tubes, guide pins, or fasteners. In an especially preferred embodiment of the invention, the guide means is slidably mounted on the handle, and is provided with means for securing the guide arm assembly at selected positions along the handle.
The preferred embodiment of the present invention includes additional features, such as provision of means for attaching nail insertion or extraction devices which are used, in conjunction with the instrument of the present invention, to drive the nail into or remove the nail from the femur. Provision is made for attachment of the nail insertion or extraction tool in a position which is slightly offset, relative to the longitudinal access of the nail, to provide additional working clearance to the surgeon, if needed.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention, when considered in conjunction with the accompanying drawings.