BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the figures, wherein like numerals represent like parts throughout the several views:
FIG. 1 is a schematic posterior view of a patient's lower back;
FIG. 2 depicts inserting a first guide wire into the patient's back of FIG.1;
FIG. 3 depicts inserting a bone needle over the first guide wire of FIG.2;
FIG. 4 depicts tapping the bone with the bone needle of FIG. 3;
FIG. 5 depicts removing the bone needle;
FIG. 6 depicts inserting the first guide member over the first guide wire of FIG. 5;
FIG. 7 depicts connecting the second guide member to the first guide member of FIG. 6;
FIG. 8 depicts setting the angle between the first and second guide members and inserting a second guide wire through the second guide member into the patient's back;
FIG. 9 depicts removing the second guide member;
FIG. 10 depicts removing the first guide member;
FIG. 11 depicts inserting a tissue dilator into over the first guide wire;
FIG. 12 depicts dilating the tissue around the first guide wire;
FIG. 13 depicts removing the inner dilator member;
FIG. 14 depicts inserting a drill into the outer dilator member;
FIG. 15 depicts drilling into the bone around the first guide wire;
FIG. 16 depicts the automatic stopping mechanism of the drilling process;
FIG. 17 depicts removing the drill;
FIG. 18 depicts inserting a first facet screw into the opening over the first guide wire;
FIG. 19 is a schematic diagram of the lower vertebra with the installed facet screws;
FIG. 20 is a schematic diagram of a pivoting guide wire;
FIG. 21 is a front perspective view of a facet screw;
FIG. 22 is a detailed view of the bottom surface of the facet screw ring of FIG. 21;
FIG. 23 is a front view of two different orientations of the facet screw ring of FIG. 22;
FIG. 24 is a front perspective view of the dilator of FIG. 11;
FIG. 25 is a front perspective view of the drill of FIG. 15; and
FIG. 26 is a front perspective view of the screwdriver of FIG. 18.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1-FIG. 19 a new method for facet fixation includes the following steps. First, patient 80 is positioned prone, lying flat on an operating table in preparation for a minimally invasive surgery (MIS) (100). Next, location 114a corresponding to a first facet joint of the L5 lumbar vertebra 84, is radiographically identified and marked on the patient's lower back. For MIS procedures, a skin incision 81 is performed and a first guide wire 112 is inserted in the facet joint location 114a (110). The placement of the guide wire 112 is verified by taking a fluoroscopic image of the patient's back. The fluoroscopic image is further used to identify the location of the facet joints 114a, 114b of vertebra 84 and the angular relationship between them. Guide wire 112 or Kirschner wire (also called K-wire) is a thin, rigid wire that is used to stabilize bone fragments in orthopedics and other types of medical and veterinary surgery. Kirschner wires were introduced in surgical procedures by Martin Kirschner in 1909. They are sterilized, sharpened, smooth stainless steel pins and have different sizes. These wires can be drilled through the bone to hold bone fragments in place. They are placed percutaneously (through the skin), thus avoiding an operation in some cases. In other cases, the K-wires are used after an operation to hold bone fragments in place. In some cases the K-wires include threads for threading into the bone. In spine surgery K-wires are used as guide wires for the placement of spine fixation components, such as screws and pins. They are inserted either through an open surgical procedure or under fluoroscopic or X-ray observation and are removed after the insertion of the screws. In one example guide wire 112 is a threaded 140 millimeter K-wire, manufacture by SpineFrontier, Inc (Beverly, Mass.).
Next, a bone needle 122 is inserted over the guide wire 112 (120) and tapped into the facet joint 114a (130). I one example, bone needle 122 is a Jamshide bone needle, manufactured by Baxter-Allegiance. The bone needle is then removed (140), and first arm 162 of an X-guide tool 400 is inserted over the guide wire 112 (150). Second arm 172 of the X-guide tool 400 is connected to the first arm 162 at pivot point 176 (160) and the angle 60 between the two arms 162, 172 is set so that a second guide wire 116 inserted through the second arm will meet the location of the second facet joint 114b of vertebra 84. Angle 60 was determined from the fluoroscopic image of the patient's back, as was mentioned above. Second guide wire is then inserted through the second arm 172 of the X-guide tool 400 into the location of the second facet joint 114b (170). Second guide wire 116 includes two elongated members 116a, 116b pivotally connected at point 117, as shown in FIG. 20. In one example, guide wire 116 is a threaded 50 centimeter pivoting K-wire, manufacture by SpineFrontier, Inc (Beverly, Mass.) and the X-guide tool 400 is a two arm angular positioning guide manufactured also by SpineFrontier, Inc (Beverly, Mass.). Next, the two guide arms 172, 162 are removed (180), (190), and the upper arm 116a of the pivoting guide wire 116 is pivoted out of the plane of the first guide wire 112, as shown in FIG. 11 (200). A tissue dilator 350 is then inserted over the first guide wire 112 (200). Tissue dilator 350 include an outer dilator cannula 352 and an inner dilator 354 configured to slide within the outer dilator cannula 352, as shown in FIG. 24. In one example, tissue dilator 350 is a dilator manufactured by SpineFrontier, Inc (Beverly, Mass.). The inner dilator 354 is advanced within the outer dilator cannula and the tissue around the first guide wire 112 is dilated (210). Next the inner dilator 354 is removed and the outer dilator cannula 352 is advanced into the patient's tissue (220), as shown in FIG. 13. Next a hand drill 360 is inserted into the outer dilator cannula (230). Referring to FIG. 25, hand drill 360 has a handle 364 and an adjustable stop 362. The distance 363 between the drill stop 362 and handle 364 is adjusted to correspond to the length of the facet screw that need to be inserted into the facet joint 114a. Accordingly, in step 240 length 363 is adjusted to match the length 301 of the facet screw 21, shown in FIG. 21 and then the handle is advanced down until it hits the stop 362 (250). In one example, hand drill 360 is a drill manufactured by SpineFrontier, Inc (Beverly, Mass.). Next, the hand drill 360 is removed (260) and a screwdriver 370 with a removable attached screw 300 is inserted in the location 114a via the outer dilator cannula 354 (270). The screw 300 is attached to location 114a and the screwdriver 370 and the outer dilator cannula 354 are removed. Referring to FIG. 26, in one example screwdriver 370 has a removable screw attaching mechanism 376 and is manufactured by SpineFrontier, Inc (Beverly, Mass.).
Next, the upper arm 116a of the second guide wire 116 is straighten and the process of dilation, drilling and screw driving is repeated for the second facet joint location 114b resulting in two facet joint screws 300a, 300b being attached to locations 114, 114b, respectively (280). Similarly, additional facet screws are driven in other facet joint locations of adjacent vertebras 82 and 86.
Referring to FIG. 21, facet screw 300 includes an elongated body 302 having a flat head 306 at one end and a threaded portion 304 at the opposite end. A washer 308 is fitter around head 306. Washer 308 is configured to pivot around the head 306 at an angle 313, as shown in FIG. 23 and has teeth 312 in the bottom surface for holding into the bone, shown in FIG. 22. In one example, facet screw 300 has a length 301 of about 40 millimeters, a non-threaded portion length 303 of 20 millimeters, a width 309 of the head of about 9 millimeters, a body width 311 of 4.5 millimeters, a washer width of 2 millimeters and a washer pivoting angle 313 of 7.5 degrees. Facet screw 300 is manufacture by SpineFrontier, Inc (Beverly, Mass.) and may be made of metal such as stainless steel or titanium, plastic, bioabsorbable material or ceramic.
Other embodiments are within the scope of the following claims. For example, second guide wire may be a non-pivoting K-wire or both first and second guide wires may be pivoting K-wires. The bottom surface of washer 308 may include ridges, serrations, grooves, or spikes.
Several embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
Patent Application
20080021480
