Source: http://patents.com/us-9808298.html
Timestamp: 2018-06-24 15:04:22
Document Index: 462226703

Matched Legal Cases: ['Application No. 201180013194', 'Application No. 2011', 'Application No. 2012', 'Application No. 2011224326', 'Application No. 201180013194', 'Application No. 201280022627', 'Application No. 201280022627', 'Application No. 2012229152', 'Application No. 2011', 'Application No. 2012', 'Application No. 09761114', 'Application No. 11710940', 'Application No. 201280038677', 'Application No. 2012267924', 'Application No. 2013', 'Application No. 2013144961', 'Application No. 201280022627', 'Application No. 201280038677', 'Application No. 2014', 'Application No. 12711719', 'Application No. 2015147534', 'Application No. 2011', 'Application No. 200980155954', 'Application No. 200980155954', 'Application No. 2012', 'Application No. 2009319879', 'Application No. 201480032876', 'Application No. 14712930', 'Application No. 2013', 'Application No. 201480012203', 'Application No. 201280038677', 'Application No. 2014', 'Application No. 2016124173', 'Application No. 14716107', 'Application No. 14724272', 'Application No. 201480073698', 'Application No. 201480014353', 'Application No. 201280038677', 'Application No. 2015147534', 'Application No. 201480012203', 'Application No. 201480032876', 'Application No. 61']

US Patent # 9,808,298. Open-architecture interference screw - Patents.com
United States Patent 9,808,298
Stroncek , et al. November 7, 2017
Stroncek; John (Boston, MA), Berube, Jr.; Alfred R. (North Attelboro, MA), Aarsvold; Kirsten H. (Mansfield, MA)
Family ID: 1000002932740
14/249,020
US 20140303676 A1 Oct 9, 2014
61810007 Apr 9, 2013
Current CPC Class: A61B 17/864 (20130101); A61B 17/869 (20130101); A61B 17/8635 (20130101); A61B 17/888 (20130101); A61F 2/0811 (20130101); A61B 17/8645 (20130101); A61F 2002/0841 (20130101); A61F 2002/0817 (20130101)
Current International Class: A61B 17/86 (20060101); A61B 17/88 (20060101); A61F 2/08 (20060101)
Field of Search: ;600/300-331
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This application claims the benefit of U.S. Provisional Application No. 61/810,007, filed on Apr. 9, 2013, and entitled, "Open-architecture Interference Screw," the entirety of which is hereby incorporated by reference.
1. An open-architecture interference screw for creating an interference fit between a bone tunnel and tissue, the screw comprising: a threaded body having a proximal end and a distal end, and a thread extending around the threaded body between the proximal end and distal end; at least one supporting spline extending along a cannulation through the threaded body between the proximal end and distal end, the at least one supporting spline engagable with a delivery device; at least one opening defined by an open surface between the thread, the at least one opening having a ratio of open surface area to closed surface area, the ratio being selected such that, when torsionally loaded, the screw does not exhibit plastic deformation when inserted into an undersized bone tunnel; and a tapered tip extending from the distal end of the threaded body, the tapered tip having a thread extending at least partway around the tapered tip; wherein a surface of the cannulation is tapered toward the distal end of the threaded body so as to form a positive seat with a corresponding tapered surface of the delivery device when the delivery device is engaged with the at least one supporting spline.
21. The open-architecture interface screw of claim 1 wherein the screw is made from a combination of poly(lactic-co-glycolic) acid, .beta.-Tricalcium phosphate, and calcium sulfate.
22. A delivery device and open-architecture interference screw combination for creating an interference fit between a bone tunnel and tissue, the combination comprising: a delivery device comprising a handle and a shaft connected to the handle, the shaft including a distal portion having a driving member, a surface of the distal portion being tapered; an interference screw comprising: a threaded body having a proximal end and a distal end, and a thread extending around the threaded body between the proximal end and distal end; at least one supporting spline extending along a cannulation through the threaded body between the proximal end and distal end, the supporting spline engagable with a delivery device; at least one opening defined by an open surface between the thread, the at least one opening having a ratio of open surface area to closed surface area, the ratio being selected such that, when torsionally loaded, the screw does not exhibit plastic deformation when inserted into an undersized bone tunnel; and a tapered tip extending from the distal end of the threaded body, the tapered tip having a thread extending at least partway around the tapered tip; wherein the interference screw is located on the distal portion of the delivery device such that the driving member engages the at least one supporting spline of the interference screw; and wherein a surface of the cannulation is tapered toward the distal end of the threaded body so as to form a positive seat with the tapered surface of the distal portion of the delivery device when the delivery device is engaged with the at least one supporting spline.
Some examples of the interface screw are made from made from a combination of poly(lactic-co-glycolic) acid, .beta.-Tricalcium phosphate, and calcium sulfate.
As best seen in FIG. 1A, there are openings 115 between adjacent proximal threads 120a,b of the interference screw 100. The interference screw 100 also includes closed surfaces 125 between adjacent distal threads 130a,b. As shown, the interference screw 100 is arranged with an open proximal portion and closed distal portion. This arrangement is advantageous because the closed surface 125 enhances the torsional strength, compressive strength and/or fexural strength (bend strength) of the distal portion of the interference screw 100. Increased structural strength is desirable at the distal end 107 of the interference screw 100 because it is prone to breaking as the interference screw 100 is inserted into an undersized pilot hole. The open proximal portion of the interference screw 100 advantageously promotes bone-to-tissue in-growth.
As best seen in FIG. 4A, there are openings 225 between adjacent proximal threads 230a,b of the interference screw 200. The interference screw 200 also includes closed surfaces 235 between adjacent distal threads 240a,b. As shown, the interference screw 200 is arranged with an open proximal portion and closed distal portion. This arrangement is advantageous because the closed surface enhances the torsional strength, compressive strength, and/or flexural strength of the distal portion 207 of the interference screw 200. Increased structural strength is desirable at the distal end of the interference screw 200 because it is prone to breaking as the interference screw 200 is inserted into an undersized bone tunnel. The open proximal portion of the interference screw 200 advantageously promotes bone-to-tissue in-growth.
A convenient example of the interference screw 200 includes, at the proximal end 206, a screw head 290. The screw head 290 has a surface 290a that extends smoothly and continuously from the threaded body 205 into a hemispherical-like end portion 290b, as shown. In use, the screw head 290 rests against graft material and damage to graft fibers is possible. Beneficially, this arrangement of the surface 290a and hemispherical-like end portion 290b reduces the chance of such damage.
FIGS. 5A-D show another example of the interference screw 200. The interference screw 200 includes a proximal portion of continuous openings 255. The continuous openings 255 are defined by a surface between proximal threads 230a,b. The continuous openings 255 completely encircle the interference screw 200. The proximal portion of continuous openings 255 advantageously promotes bone-to-tissue in-growth.
The interference screw 200 further includes a distal portion of discontinuous openings 260. The discontinuous openings are defined by a surface between distal threads 240a,b. Along a path of the surface, the surface alternates openings 225 and closed surface areas 235. This alternating pattern of openings 225 and closed surface areas 235 improves the torsional and flexural strength of the distal portion of the interference screw 200 that advantageous to insert in the interference screw 200 into a bone tunnel.
In the example of the interference screw 200 shown, the openings 225 and closed surface areas 235 of the distal portion of discontinuous openings are arranged 90.degree. to each other. For example, there is opening 225 and when the interference screw 200 is rotated 90.degree., there is a closed surface area 235. It may be convenient to call this arrangement of the openings 225 and closed surface areas 235 asymmetrical. Other arrangements are possible, for example the openings 225 and closed surface areas 235 are arranged at an angle less than 90.degree. or greater than 90.degree.. The interference screw 200 with asymmetrical arrangement of openings 225 and closed surface areas 235 has a tip strength greater than an interference screw with openings only. High tip strength is advantageous to inserting the interference screw 200 into a undersized bone tunnel.
FIGS. 7A-C show another example of the interference screw 200. The interference screw 200 has an alternating pattern of openings 225 and closed surface areas 235. The alternating pattern extends over a length or substantially the entire length of the interference screw 200 (as shown). The openings 225 are between alternating pairs of adjacent threads 275. For example, the opening 225a is between a first pair of adjacent threads 275a and the opening 225b is between a second pair of adjacent threads 275b. The closed surface areas 235 are between alternating pairs of adjacent threads 275. For example, the closed surface areas 235a is between a third pair of adjacent threads 275c and the closed surface area 235b is between a fourth pair of adjacent threads 275d.
FIGS. 9A and 9B shows an example driver 300 used to insert the interference screw 200 into a bone tunnel (hole). The driver 300 includes a handle assembly (not shown) and a shaft 305 coupled to the handle assembly. The shaft includes a distal end 306 and a driving member 310 (four shown) extending from the distal end 306, and an opening for a guide wire used to position the screw during insertion (not shown). If desired, the drive member 310 extends a partial length of the shaft 305. The driving member 310 includes driving surfaces 315a,b for engaging the corresponding surfaces of the supporting spline 245.
An example of the tapered tip 410 has a first partial thread 430 and second partial thread 435 extending partway or less than 360.degree. around the tapered tip 410. The first and second threads 430, 435 each start and stop at different locations on the surface 425 of the tapered tip 410. In a convenient example of the tapered tip 410, the first partial thread 430 starts in the distal region 420 at point 440a and extends about 180.degree. around the tapered tip 410 (best seen in FIGS. 10C and 10D with the threaded body 405 is removed for clarity) and stops at point 440b in the proximal region 415. The second partial thread 435 starts at point 445a distal to the stopping point 440b of the first partial thread 430. The second partial thread 435 extends about 180.degree. around the tapered tip 410 (also best seen in FIGS. 10C and 10D) and stops at point 445b in the proximal region 415. The stopping point 440b of the first partial thread 430 and starting point 445a of the second partial thread 435 are spaced a distance D from one another. In other examples of the tapered tip 410, the first partial thread 430 and the second partial thread 435 are discontinuous or separate from one another.
In one example of the tapered tip 410, the partial threads 430, 435 taper towards the proximal region 415 with the same taper as the tapered tip 410. The minimum diameter of a given partial thread is at the distal terminus of the partial thread. The diameter of the partial thread increases to a maximum towards the proximal region 415 of the tapered tip 410. In a convenient example, the partial threads 430, 435 each have tapered ends, of which tapered ends 430a and 435a are shown in FIG. 10B. Each of the tapered ends has a height above the surface 425 of the tapered tip 410 and terminates at the same height as the surface 425. The smooth transition between the partial threads 430, 435 and the surface 425 of the tapered tip 410 advantageously minimizes damage to a graft from the interference screw 400.
Tracing an example of the partial thread with tapered ends, starting from the distal terminus of the partial thread, the diameter of the partial thread increases until a maximum is reached near the proximal region 415. Continuing to trace the partial thread past the maximum diameter, the diameter of the partial thread decreases until the proximal terminus of the partial thread is reached. In foregoing example, the partial thread extends about 180.degree. around the tapered tip 410 but reaches a maximum diameter (and maximum root diameter) in less than 180.degree..
While the foregoing examples of the tapered tip 410 are described as having two partial threads, it should be apparent that any number of partial threads are possible, such as three or four. For example, FIG. 11 shows another example of the tapered tip 410 with one partial thread 450 extending partway or about 300.degree. around the tapered tip 410.
In some examples, the interference screw 100, 200, 400 may be completely or a portions thereof (e.g., the threaded body) made from a formulation of poly(lactic-co-glycolic) acid (PLGA), .beta.-Tricalcium phosphate (.beta.-TCP) and calcium sulfate, poly-L-lactic acid-hydroxyapatite (PLLA-HA), poly-D-lactide (PDLA), polyether ether ketone (PEEK) or variants thereof. Biocomposite examples of the interference screw 100, 200, 400 made from a combination of PLGA, .beta.-TCP, and calcium sulfate are absorbable by the body, which is beneficial to natural healing. An example formulation of PLGA, .beta.-TCP, and calcium sulfate is described in U.S. Pat. No. 8,545,866, the entirety of which is herein incorporated by reference. A copolymer of polyglycolic acid (PGA) and polytrimethylene carbonate (TMC) is another example of a bioabsorbable material. Other commonly used materials for implants are also contemplated by this disclosure. In any case, the interference screw 100, 200, 400 comprise a material that is capable of providing the strength needed to set the fixation device into position and to hold the tissue in position while bone-to-tissue in-growth occurs.
To examine the performance of the open-architecture interference screw, finite element analysis was used to simulate inserting the screw into an undersized bone tunnel with a delivery device. In the analysis, torque (torsional load) was applied to the inner portion of the screw that is in contact with the delivery device while the distal end of the screws was held in place. The torque at which the sample plastically deformed was recorded as the failure torque. The failure torque provides a measure of the torsional strength of a screw. The results of the analysis for a medium-size or 7 mm.times.25 mm (diameter by length) interference screw made from the formulation of PLGA, .beta.-TCP, and calcium sulfate, described above, is provided below. (Similar results were found when the interference screw is made from PLLA-HA.)
TABLE-US-00001 Failure Torque Open Area to Closed Sample (in * lb) Area Ratio 1 Control (solid screw) 18.26 0 to 1 2 Sample 1 17.2 1 to 11 3 Sample 2 15.23 1 to 11 4 Sample 3 13.86 1 to 5 5 Sample 4 16 1 to 4 7 Sample 5 13.33 1 to 3 8 Sample 6 5.59 1 to 2
Unexpectedly, increasing the degree of openness to one unit of open surface area to three units of closed surface area did not further decrease the torsional strength of the screw total but improved the torsional strength (increased from 13.86 to 16 in*lb). Increasing the degree of openness beyond this ratio, however, did not improve the performance but rather decreased performance (decreased from 16 to 13.33 in*lb). The results, therefore, demonstrate that for a medium-sized screw (e.g., 8 mm.times.25 mm), a ratio of about one unit of open surface area to about four units of closed surface area provides superior results. The results also demonstrated that, surprisingly, thickening the supporting splines provided better performance then thickening the threads of the screw.
Similar testing was performed with other sizes of screws. For a large-sized screw (e.g., 12 mm.times.25 mm), a ratio of about one unit of open surface area to about three units of closed surface area was determined to provide superior results. For a small-sized screw (e.g., 6 mm.times.20 mm), a ratio of about one unit of open surface area to about five units of closed surface area was determined to provide superior results. In some examples, increasing the wall thickness of the screw (e.g., when increasing the size of the screw), also increased the degree of openness.
For a large-sized screw (e.g., 12 mm.times.25 mm) made from PEEK, a ratio of about one unit of open surface area to about two units of closed surface area was determined to provide superior results. For a medium-sized screw (e.g., 8 mm.times.25 mm) made from PEEK, a ratio of about one unit of open surface area to about two units of closed surface area and a half was determined to provide superior results. For a small-sized screw (e.g., 6 mm.times.20 mm) made from PEEK, a ratio of about one unit of open surface area to about three and a half units of closed surface area was determined to provide superior results.
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