Abstract:
A targeting device for aligning a viewing device between a radiation source and a radiation receiver along an axis that passes through the fastener-receiving hole in an intramedullary nail or rod. The targeting device is aligned such that the viewing axis coincides with the radiation axis, which in turn coincides with an axis that passes through the fastener-receiving hole, to prepare to insert a fastener for attaching the nail to a bone in which the nail is implanted. 
     The apparatus and method reduces the procedural time associated with the accurate placement of screws or pins into orthopedic hardware, such as the distal locking holes of intramedullary nails/rods in long bone fractures.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a targeting device for inserting a fastener into the distal end of a femoral nail. 
     Intramedullary nailing has become one of the most effective methods for stabilizing orthopedic shaft fractures. Designs that interlock bone and nail have expanded the indications for Intramedullary Nailing (IM) considerably. 
     These interlocking nail designs, while generally successful, are associated with some difficulties, such as an inability to localize the distal locking holes and missed locking, that result in prolonged operating and fluoroscopy time. In addition, since no reliable distal targeting device has been developed, most surgeons are exposed to considerable radiation during distal screw insertion. 
     The problem of properly inserting the distal locking screws from outside the limb of the patient into corresponding screw holes in the nail is a challenging one. The proper positioning of such locking screws or pins is typically the most time-consuming and difficult portion of the overall nail implantation procedure. 
     A number of different approaches have been taken in attempting to find an effective, safe, simple, and rapid method. These include U.S. Pat. No. 5,772,594 issued Jun. 30, 1998, to Earl F. Barrick for “Fluoroscopic Image Guided Orthopaedic Surgery System with Intraoperative Registration”; U.S. Pat. No. 5,540,691 issued Jul. 30, 1996 to John A. Elstrom and Peter Elstrom for “Optical Distal Targeting method for an Intramedullary Nail”; U.S. Pat. No. 5,013,317 issued May 7, 1991 to J. Dean Cole and A. Glenn Durham for “Medical Drill Assembly Transparent to X-rays and Targeting Drill Bit”; U.S. Pat. No. 4,976,713 issued Dec. 11, 1990 to Joël Landanger and Jean P. Michel for “Aiming Device to Position at Least One Fixing Component of the Centromedullar Nail Type, Through an Implant”; U.S. Pat. No. 4,803,976 issued Feb. 14, 1989 to Robert Frigg et al. for “Sighting Instrument”; U.S. Pat. No. 4,667,664 issued May 26, 1987 to Harold S. Taylor and John C. Taylor for “Blind Hole Targeting Device for Orthopedic Surgery”; and U.S. Pat. No. 4,418,422 issued Nov. 29, 1983 to Karl M. Richter et al. for “Aiming Device for Setting Nails in Bones”. 
     Typically, a C-arm x-ray provides an image for the surgeon to view the locking holes in the nail. It is necessary to precisely align the axis of the targeting device with the axis of the locking holes after the radiation axis of the x-ray has been aligned with the locking holes. Usually prior art viewing devices employ a carriage mounted on a mounting plate to move the targeting device in at least 2 degrees of freedom, in planes generally parallel to the nail to locate the axis of the targeting device with the locking holes. The viewing axis of the targeting device must be precisely located to coincide with the axis of the locking holes. 
     SUMMARY OF THE INVENTION 
     The broad purpose of the present invention is to provide an improved method and device for aligning the axis of a fastener insertion (locking) hole with the axis of the holes in the orthopedic hardware, such as the distal end of a femoral nail. 
     In the preferred embodiment, a mounting plate is strapped on the user&#39;s limb adjacent the distal end of the nail. The targeting device is slidably supported on rods disposed in a plane generally parallel to the implanted nail. A ball and socket joint supports the targeting device so that it can be rotated with the aid of a radiation source that is aligned with the locking holes until the viewing axis coincides with the axis of the locking holes. The bone is drilled and then the fastener is inserted both through the targeting device and the nail. 
     The intent/purpose of the invention is as follows: to improve the reliability/accuracy of alignment; to eliminate surgeon exposure to the associated radiation; to be inherently easy to use; and to improve the associated procedural time of surgery. 
     The principle features of the invention include: a one step adjustment for each the x and y directions; a ball and socket joint supporting the targeting device for spherical adjustment such that the viewing axis coincides with the axis of the distal holes of the nail; hands-free operation during x-ray; and a tourniquet design for secure attachment to the patient. 
     The procedure and apparatus may be used in other long bone fractures, such as a humeral bone, and for use either with a solid or hollow nail. 
     Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views, and in which: 
     FIG. 1 illustrates a targeting device embodying the invention; 
     FIG. 2 is a plan view of the targeting device of FIG. 1; 
     FIG. 3 is a view as seen along lines  3 — 3  of FIG. 2; 
     FIG. 4 is a view as seen along the lines  4 — 4  of FIG. 2; 
     FIG. 5 is a fragmentary view illustrating how the targeting device is aligned with the holes in the nail; 
     FIG. 6 is a fragmentary view similar to FIG. 5 but at right angles thereto; 
     FIG. 7 is a perspective view of another targeting device embodying the invention; 
     FIG. 8 is a plan view of the targeting device of FIG. 7; 
     FIG. 9 is a sectional view as seen along lines  9 — 9  of FIG. 8; 
     FIG. 10 is a sectional view as seen along lines  10 — 10  of FIG. 8; 
     FIG. 11 is a view as seen along lines  11 — 11  of FIG. 8; 
     FIG. 12 is a view as seen along lines  12 — 12  of FIG. 8; 
     FIG. 13 is a perspective view of still a further embodiment of the invention employing a double ball and socket joint; 
     FIG. 14 is a longitudinal sectional view of the targeting device of FIG. 13; 
     FIG. 15 is a perspective view of still another embodiment of the invention employing a universal joint; 
     FIG. 16 is a plan view of the device of FIG. 15; 
     FIG. 17 is an enlarged fragmentary view of the U-joint; 
     FIG. 18 is a sectional view showing how a preferred targeting device illustrating the invention can be mounted on a fixed surface rather than being strapped to the patient&#39;s limb; 
     FIG. 19 is a view showing how a targeting device illustrating the invention can be strapped to the patient&#39;s limb employing an inflatable tourniquet; and 
     FIG. 20 is a view showing a targeting device illustrating the invention attached to a femoral nail. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, FIG. 1 illustrates a preferred targeting device, generally indicated at  10 , attached by strap means  12  to the leg  14  of a patient, in a relatively fixed position with respect to the leg. Targeting device  10  includes a curved, rectangular, rigid plate-like base  16 . The base has a central, rectangular opening  18  disposed adjacent the distal end of a conventional hollow femoral nail  20  implanted in a fractured femur  21 , illustrated in FIG.  5 . 
     The base has four upright apertured posts  22 ,  24 ,  26  and  28  adjacent the four corners of the plate. Straight guide rod  30  is supported in the apertures of posts  22  and  24  above the base plate on one side of opening  18 . One end of the guide rod is threaded to receive a pair of locking nuts  32  and  34  for rigidly fastening the guide rod to the upper end of post  22 . The opposite end of guide rod  30  has a ball joint  35  mounted in a ball-shaped socket  36  at the upper end of port  24 . 
     A second straight guide rod  38  is received through the apertures of posts  26  and  28 . One end of guide rod  38  is threaded to receive a pair of fasteners  40  and  42 . The opposite end of guide rod  38  has a ball-joint  44  received in a ball-shaped socket  46  at the upper end of post  26  in such a manner that guide rod  38  is parallel to guide rod  30 . 
     Both of the guide rods are disposed in an imaginary plane that is generally parallel to the longitudinal axis of femoral nail  20 . 
     Referring to FIGS. 2 and 4, a tubular linear guide sleeve  50  has a pair of opening means  52  and  54  mounted on guide rods  30  and  38 , at right angles to the parallel axis of the two guide rods. 
     As best shown in FIG. 4, a pin  56  is telescopically received in sleeve  50 . The pin has a pair of opening means  58  and  60  aligned with the openings in the guide sleeve to slidably receive guide rods  30  and  38 . One end of the sleeve is closed at  62  to provide a housing for a spring-bias member  64  which biases pin  56  and the sleeve in opposite directions to frictionally engage guide rods  30  and  38  in an adjustable releasable position. 
     The pin has an enlarged head  66  having a diameter larger than the open end of the sleeve and normally spaced from the sleeve a sufficient distance so that the user can release the pin and the sleeve from their frictional engagement on the two guide rods by pushing head  66  toward spring  64 . The user can then precisely locate the position of the sleeve on the two guide rods. 
     Referring to FIG. 4, pin  56  has a slot  68  aligned with a slot  70  in sleeve  50 . A locking sleeve  72  is frictionally slidably mounted on the guide sleeve over slot  68  and slot  70 . A plunger  74  is mounted in slots  68  and  70 . The plunger has a lower threaded end  76  received in a cross bar  78 . A spring  80  is mounted between the head of the plunger and the locking sleeve to bias the plunger and cross bar  78  toward the locking sleeve. 
     Cross bar  78  carries a pair of Y-shaped supports  82   a  and  82   b  which cradle sleeve  50 . Plunger  74  is pushed downwardly as viewed in FIG. 4, with supports  82   a  and  82   b  to move it to an adjusted position along the length of slot  68 , and then released to permit supports  82   a  and  82   b  to frictionally lock the locking sleeve in an adjusted position along sleeve  50 . 
     Locking sleeve  72  supports an L-shaped cradle  84  as illustrated in FIGS. 3 and 4. The cradle and a lower plate  85  are connected together by fasteners, not shown, to define a partially spherical socket  86  suspended above opening  18 . 
     Still referring to FIG. 3, a tubular target housing  88  has an integral ball-shaped, slotted, expandable joint  90  frictionally received in socket  86  so that longitudinal target axis  92  can be rotated to an adjusted angle with respect to the nail. Axis  92  passes through the center of rotation of joint  90 . 
     Joint  90  has an internally tapered opening  94 . An elongated clamping element  96  has an externally tapered surface  98  that is complementary to tapered opening  94 , and a cylindrical midsection  100  that is slidably mounted in a cylindrical extension of tapered opening  94 . Clamping element  96  is shown in FIG. 3 clamping joint  90  in socket  86 . 
     A plunger  102  is slidably mounted in an opening  104  of housing  88 . A spring  106  is disposed at the lower end of plunger  102 . The spring is retained between the plunger and an internal shoulder  108  in housing  88  in such a position that by pushing down on head  109  of the plunger, clamping element  96  is lowered in tapered opening  94  to release the joint. The joint can then be rotated to adjust the angle of the target axis with respect to the nail locking openings. 
     The outer end of housing  88  has a pair of gripping fingers  109 A and  109 B that permit the user to depress plunger  102  when he is adjusting target axis  92  with respect to the nail. 
     Although this embodiment illustrates an internal clamping element, a solid ball with a viewing hole, and an outside clamping means could also be used. 
     Plunger  102  and clamping element  96  define an opening  103 , which passes through the ball joint and has a sufficient diameter to receive a sleeve (not shown). 
     Referring to FIGS. 5 and 6, in use, the patient&#39;s leg  14  is mounted between the radiation discharge end  110  and the radiation-receiving end  112  of a conventional C-shaped x-ray device. The x-ray device passes radiation along a radiation axis  114  through opening  103 . The position of the radiation device is adjusted until radiation axis  114  coincides with the axis  116  of a pair of aligned nail locking holes  118  and  120  in the wall of nail  20 . When the radiation axis  114  is aligned with hole axis  116 , the user can view the position of the locking holes  118  and  120  through a conventional x-ray image screen, not shown. 
     He then moves the target housing  88  along guide rods  30  and  38 , and along guide sleeve  50  until the target housing is proximate nail locking holes  118  and  120 . He rotates the target housing and the ball joint in socket  86  to adjust the angle of target axis  92  until it is aligned with hole axis  116 . 
     He then inserts a drill, not shown, through the sleeve in the target housing along axis  92  to drill holes in the bone that are aligned with the locking holes. He removes the drill and sleeve and then inserts a fastener into the target housing, into the holes in the bone and the nail, and screws the nail to the bone. 
     As is well known, this procedure is typically accomplished in order to permit a fracture  124  to set when the bone segments are aligned on the nail. 
     FIGS. 7 through 12 illustrate a preferred targeting device  200 . Targeting device  200  is mounted in a fixed position on the patient&#39;s leg and includes a frame  202 . The frame includes a pair of end members  204  and  206  connected together by a pair of upper parallel frame rods  208  and  210 , and a lower pair of strapping rods  212  and  214 . 
     Frame  202  also has a cross member  216  at the upper end of the end piece  204 , and an identical cross member  218  at the upper end of end piece  206 . 
     Referring to FIG. 9, an elongated telescopic support  220  has one end mounted on cross member  218 . The opposite end of the telescopic support carries a targeting device  222 , supported in a cantilever fashion with respect to cross member  218 . 
     Support  220  comprises a pair of telescopically engaged tubular members  224  and  226  so that the suspended end of support  220  can be moved either toward or away from cross member  218  in order to precisely locate the targeting device with respect to the nail. 
     Tubular member  224  has an upright hollow support  227 . A vertical locking pin  228  is mounted in support  227 . A push button  230  is carried on the upper end of pin  228 . A coil spring  232  is mounted between push button  230  and a shoulder  234  inside support  227  so that the locking pin can be pushed downwardly to release a locking shoe  236  that engages the bottom surface of cross member  218 . When the telescopic support is properly oriented, locking pin  228  is released to lock the targeting device in a selected position along cross member  218 . 
     Referring to FIG. 9, inner tubular member  226  supports a tubular vertical housing  242 . A locking pin  244  is slidably disposed in housing  242  and through a slot  243  in support  220 . A push button  246  is carried at the upper end of locking pin  244 . A spring  247  is mounted beneath push button  246  and a shoulder  248  to bias the pin upwardly. The lower end of the locking pin has a locking shoe  250  that frictionally engages support  220  so that when the push button is pushed downwardly, the two tubes can be longitudinally moved with respect to one another in order to increase the overall suspended length of the support. 
     Referring to FIGS. 7 and 11, the extreme suspended end of the telescopic support has a socket  252  with an internal partially spherical bearing socket  254 . The targeting device includes a viewing tube  256  having a partially spherical, split, expandable ball  258  received inside socket  254  so that the targeting device can be swung in an orbit about a targeting axis  260  to precisely align axis  260  with the nail locking openings. 
     An elongated locking tube  262  has a lower tapered end  264  received in a tapered opening  266  of expandable ball  258 . A push button  268  is carried at the upper end of the locking tube to push it downwardly from tapered opening  266  thereby freeing ball  258  to permit rotation of the targeting device in socket  252 . When the push button is released, a spring  270  biases the locking tube upwardly so tapered end  264  locks the ball in the socket. 
     Tube  262  and push button  268  also define a through opening  265  for receiving a drill, a drill sleeve and then a fastener. 
     In use, the targeting device is adjusted in a similar manner to the embodiment of FIGS. 1 through 6, that is, the targeting device is extended along the axis of the telescopic support and adjusted along cross member  218  to align the targeting axis  260  with the nail locking holes. 
     A sleeve, not shown, is inserted in locking tube  262 . A drill is inserted in the sleeve in the conventional manner to drill a hole in the patient&#39;s femur. The drill and sleeve are then removed and a threaded fastener inserted through opening  265  into the drilled hole to attach the femur to the nail. 
     FIGS. 13 and 14 illustrate another targeting device  300  illustrating the invention. Targeting device  300  comprises a frame end piece  302  and frame end piece  304  connected by four parallel rods  306 ,  308 ,  310  and  312 . Rods  308  and  310  provide means for strapping the targeting device on the user&#39;s limb in manner that will be presently described. 
     The frame end pieces carry a pair of tubular parallel slotted cross rods  314  and  316  at their respective ends. 
     A targeting device  318  is suspended from tubular support  320  cross rod  314 . Support  320  includes a tubular section  322  having a slot  323  and a leg  324  rotatably mounted on cross rod  316 . Leg  324  can be adjusted along cross rod  314 . 
     Leg  324  includes a tubular housing  326 . A locking pin  328  is telescopically received in housing  326 . A push button  330  is carried on the upper end of locking pin  328 . A spring  332  mounted between push button  330  and a shoulder  334  in the housing to bias the locking pin upwardly to a locking position. The locking pin can be pushed downwardly to release a locking shoe  335  from the cross rod to slide the housing along the cross rod. A pin  336  in slot  336   a  in the cross rod prevents housing  326  from rotating about the cross rod. 
     The inner end of support  320  is rotatably connected to a support section  340  to permit the lower portion of targeting body  342  to be swung in the direction of arrows  344  to adjust the angle of viewing axis  346  of the targeting body. 
     A locking tube  348 , carried on tubular support  320 , has a locking pin  350  which is pushed downwardly by a push button  352  to disengage a locking shoe  354  from support  320 . The push button is then released, and biased upwardly by a spring  355  to cause the shoe to frictionally engage support  320  to lock the lower end of locking tube  348  in position. 
     Targeting body  342 , as best seen in FIG. 14, has a generally longitudinal viewing bore  356  with a diameter sufficient to receive a sleeve and drill for forming a hole in the patient&#39;s femur. Body  342  has a lower, partially spherical exterior annular surface  358  and an upper partially spherical annular surface  360 . Lower spherical surface  358  is mounted in a spherical socket  362  suspended from the lower end of locking tube  348 . 
     A second support leg  370  is slidably mounted on cross rod  314 , and carries a support tube  372  having a slot  373 . A locking tube  374  is attached to support tube  372  and carries a locking pin  376  with a push button  378 . Pin  376  is received in the slot of cross rod  314 . Push button  378  is depressed to push the locking pin downwardly against the bias of a spring  380  to release a locking shoe  382  carried on the lower end of the pin and engaged with cross rod  314 . Leg  370  is then slid along cross rod  314 . When the targeting body is located in an appropriate position, the push button is released so that locking shoe  382  locks support leg  370  in position. 
     Leg  370  has an elbow  384  rotatably mounted on cross rod  314 . A pin  385   a  is carried by the elbow and received in slot  385   b  to prevent rotation of support tube  372  about the cross rod. 
     A locking tube  386  is carried on support tube  372  and has a locking pin  388  with a push button  390  for pushing the locking pin downwardly through locking tube  386  to release shoe  392 . Locking pin  388  extends through slot  373  in tube  372 . When the angle of the viewing axis has been properly located, the push button is released and pushed upwardly by a spring  394  to lock the upper half of the targeting body in position. 
     When the targeting device has been locked in position, the process for drilling a hole in the femur and then inserting the fastener through viewing bore  356  is achieved in the manner described with reference to the other embodiments of the invention. 
     FIGS. 15 through 17 illustrate targeting device  400 , which represents another modification of targeting device  300 . It employs a frame having end pieces  302  and  304  connected by rods  306 ,  308 ,  310  and  312  as in the embodiment of FIG.  13 . The support structure is identical to that of the embodiment of FIG.  13 . However, the targeting structure comprises a tubular U-joint housing  402  having a lower end  404  pivotally supporting a pivot pin  406 . The ends of pin  406  are pivotally connected to a second pin  407  about an axis at right angles to the axis of pin  406 . The ends of pin  407  are connected by arm means  408  to the lower end of locking tube  348 . Housing  402  has a target opening  409  which passes through the pivot pin. 
     The upper end of housing  402  supports a pivot pin  412  which is pivotally connected to the lower end of locking tube  386  and a second pivot pin  413  so that the upper end of the U-joint housing can be swung toward and away from cross rod  314 . This permits the viewing tube to be pivoted about the axis of the four pivot pins. When locked in position, the targeting device is then used for drilling the bone, and then inserting the fastener through opening  409  as previously described. 
     FIG. 18 illustrates how targeting device  400  can be mounted on a relatively fixed surface  420  by modifying frame  302  so that it straddles the patient&#39;s leg  14  rather than being strapped to the leg. 
     FIG. 19 shows another method for mounting a targeting apparatus such as is illustrated in FIG.  7 . In this case, an inflatable tourniquet  450  is wrapped around both the patient&#39;s leg and the two strapping rods and then inflated in the customary manner by delivering air through a tube  452  so that the targeting device is firmly anchored on the user&#39;s leg. 
     FIG. 20 shows still another method for mounting the targeting device of FIG.  19 . In this case the frame is attached by a support rod  470  which extends generally parallel to the femur and, in turn, is connected to a second support rod  472  by a suitable locking joint  474 . Rod  472  is disposed at right angles to rod  470 . The other end of the rod  472  carries a locking structure  476 , which is attached to the nail so that the targeting device can be used to locate the locking holes.