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METHODS AND INSTRUMENTS FOR TREATING PSEUDOARTHROSIS
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims the benefit of United States Provisional Application Serial No. 60/242,950 filed on October 24, 2000, which is hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
The present invention relates generally to methods and instruments for treating pseudoarthrosis.
Back pain affects millions of individuals and is a common cause of disability for the middle-aged worfang population. A frequent cause of back pain is rupture or degeneration of intervertebral discs. In many instances, the only relief from the symptoms of these conditions is a discectomy, or surgical removal of all or a portion of an intervertebral disc. Additionally, the disc space height must be maintained or restored. One solution to the stabilization of an excised disc space is to fuse the adjacent vertebrae between their respective endplates. Typically a spacer or implant is inserted into the treated or prepared disc space until complete arthrodesis is achieved. The spacer/implant must provide temporary support and allow bone ingrowth. Success of the discectomy and fusion procedure requires development of a contiguous growth of bone or an osseous bridge to create a solid mass between the vertebrae to withstand the compressive loads on the spine for the life of the patient.
Several metal spacers have been developed to fill the void formed by the discectomy and to promote fusion. Sofamor Danek Group, Inc., (Memphis, TN) markets a number of hollow spinal cages, and a wide vaπety of other such cages are known in the art. For example, U.S. Patent Nos. 5,015,247 and 5,984,967 to Michelson et al. and Zdeblick et al, respectively,
disclose threaded spinal cages. The cages are hollow and can be filled with osteoinductive material, such as autograft and allograft, prior to insertion into the intervertebral disc space. Apertures defined in the cages communicate with the hollow interior to provide a path for tissue growth between the vertebral endplates.
Although some success with respect to spinal fusions has generally been obtained with respect to interbody fusions or intertransverse process fusions, the incidence of pseudoarthrosis, also known as pseudarthrosis, or failure of a spinal fusion, may be relatively high in certain circumstances. For example, the incidence of pseudoarthrosis has been reported as high as 40% for smokers, as well as for patients having multilevel fusions and unrecognized metabolic disease. Pseudoarthrosis has been shown to be the contributing cause of symptoms in 78% of symptomatic patients requiring reoperation, with each reparative procedure decreasing the probability of success. Moreover, at least about 90% of attempted posterolateral intertransverse process fusions with autogenous iliac crest bone grafting in Lewis rats fail.
In order to treat symptomatic pseudoarthrosis, a conventional, open surgical procedure includes direct exposure of the fusion mass, decortication, bone regrafting and possibly reinstrumentation or addition of new graft and/or new instrumentation. The repair procedure can be very complex, is highly invasive and additional posterior fusion procedures may need to be performed to stabilize the spine after a fusion has failed. Thus, simpler, less invasive methods for treating spinal pseudoarthrosis are needed.
3 SUMMARY OF THE INVENTION
It has been discovered that administration of an osteoinductive composition to a location of pseudoarthrosis, such as spinal pseudoarthrosis, is effective in promoting bone growth for treating the pseudoarthrosis.
Accordingly, in one aspect of the invention, methods of treating spinal pseudoarthrosis are provided.
In one form of the invention, a method includes delivering to a location of pseudoarthrosis an effective amount of an osteoinductive composition. Preferably the osteoinductive composition is combined with an acceptable carrier, such as a calcium phosphate-containing carrier. The osteoinductive composition is effective in promoting bone growth for treating the spinal pseudoarthrosis.
In preferred forms, the method includes advancing a first elongated member to a location of spinal pseudoarthrosis in a patient. The first elongated member has a proximal end, a distal end and a lumen extending longitudinally therethrough. The method further includes advancing the osteoinductive composition described herein through the lumen of the first elongated member. In other preferred forms of the invention, the osteoinductive composition is advanced through the lumen of the elongated member to a pseudoarthrotic mass into and extending across the pesudoarthrotic mass.
The methods described herein may be accomplished with or without decortication and, in the case of a failed interbody fusion, without removal of the implant. Further the methods can use minimally invasive surgical procedures that can significantly reduce morbidity associated with surgery, reduce the duration of a hospital stay and reduce patient recovery times.
In other aspects of the invention, surgical instruments are provided.
The instruments are advantageously configured for use in the methods of treating spinal pseudoarthrosis described herein. In one form of the invention, a cannulated drill is provided that includes an elongated member having a
proximal end, a distal end, an inner surface, and an outer surface. The inner surface defines a lumen that extends along the length of the elongated member and is sized to receive an elongated obturator The distal end of the elongated member has at least one bone cutting edge. The proximal end of the elongated member has a connector configured for matingly engaging a distal end of a syringe to the proximal end of the elongated member. The elongated member is preferably formed of a biocompatible material.
Surgical instrument assemblies are also provided including at least the cannulated drill described herein and a syringe. The syringe has a housing that defines a cavity and has a proximal end and a distal end. The distal end of the syringe is matingly engageable to the proximal end of the elongated member. The lumen of the elongated member and the cavity of the housing are in fluid communication when the distal end of the syringe and the proximal end of the elongated member are matingly engaged.
5 BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a side elevation view of one embodiment of a drill provided according to the present invention. FIG. 2 is a first end view of the drill of FIG. 1
FIG. 3 is a side elevation of an alternative embodiment of a drill having a plurality of apertures extending along a length of the drill for use in the present invention.
FIG. 4 is a side elevation view of an elongated obturator for use in a drill according to the present invention.
FIG. 5 is a first end view of the obturator of FIG. 4. FIG. 6A is a side elevation view partially broken away of an obturator/drill assembly according to the present invention.
FIG. 6JB is a first end view of the obturator/drill assembly of FIG. 6. FIG. 7 is a side elevation view of an alternative embodiment of a drill for use in the present invention.
FIG. 8A is an exploded view of a syringe-drill assembly provided according to the present invention.
FIG. 8B is a side elevation view of the syringe-drill assembly of FIG. 8A.
FIG. 8C is an exploded view of an alternative embodiment of a syringe-drill assembly provided according to the present invention.
FIG. 9 is a side elevation view an elongated delivery member having apertures extending along a length of the member provided according to the present invention.
FIG. 10A is a side elevation view of a pair of vertebrae depicting pseudoarthrosis at an intertransverse process fusion site.
FIG. 1 OB is a side elevation view of the pseudoarthrosis of the pair of vertebrae of FIG. 10A with a guide wire inserted into a pseudoarthrotic mass. FIG. 1 1 is an enlarged view of the pseudoarthrosis site of FIG. 10A illustrating a cannula positioned adjacent the treatment site.
FIG. 12 is a side elevation view of the pseudoarthrotic mass of FIG. 1 1 depicting a cannulated drill having an obturator disposed in its lumen.
FIG. 13 is a side elevation view of FIG. 12 depicting a drill in a bored hole in the pseudoarthrotic mass. FIG. 14 is a side elevation view of the pseudoarthrotic mass of FIG. 13 depicting the drill without the obturator.
FIG. 15 is a side elevation view of the pseudoarthrotic mass of FIG. 14 depicting a syringe connected to the drill according to the present invention.
FIG. 16 is a side elevation view of the pseudoarthrotic site of FIG. 15 partially broken away and depicting delivery of an osteoinductive composition into a bored hole in the pseudoarthrotic mass according to the present invention.
FIG. 17 is a side elevation view of the pseudoarthrotic mass of FIG. 11 depicting a plurality of holes bored into the mass according to one embodiment of the present invention.
FIG. 18 is a side elevation view in partial section illustrating a fusion cage between a pair of vertebrae wherein a drill is positioned in a pseudoarthrotic mass located within a fusion cage according to another embodiment of the present invention. FIG. 19 is a cross-section view taken along line 19~19 of FIG. 18, illustrating a intervertebral implant, between adjacent vertebrae depicting a plurality of bore holes drilled in the pseudoarthrotic mass inside the implant chamber, as well as in the superior vertebral bodies, adjacent to the implant.
7 DESCRIPTION OF THE EMBODIMENTS
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications of the invention, and such further applications of the principles of the invention as illustrated herein, being contemplated as would normally occur to one skilled in the art to which the invention relates. The present invention relates to methods and instruments for treating pseudoarthrosis. Pseudoarthrosis, also known as pseudarthrosis, refers to a condition that arises due to an incomplete bone fusion process. With respect to spinal pseudoarthrosis, this includes failure of adjacent vertebrae to fuse or the presence of some other bone discontinuity in the fusion mass. That is, the bone of the spinal fusion is not contiguous, such that a non-union, or a gap between the bone, exists. In a first aspect of the invention, embodiments of methods include delivering to a location of spinal pseudoarthrosis an effective amount of an osteoinductive composition. The composition advantageously includes an osteoinductive factor, such as in a pharmaceutically acceptable carrier. The osteoinductive composition is effective in promoting bone growth to treat the spinal pseudoarthrosis.
In a second aspect of the invention, embodiments of surgical instruments are provided. In one form, a surgical instrument includes a cannulated drill including an elongated member formed of a biocompatible material and having a proximal end, a distal end, an inner surface, and an outer surface. The inner surface defines a lumen that extends along the length of the elongated member and is sized to receive an elongated obturator. The distal end of the elongated member has at least one bone cutting edge. The proximal end of the elongated member has, or otherwise defines, a connector configured to matingly engage a distal end of a syringe. Embodiments of surgical instrument assemblies are also provided that include the drill described herein
and a syringe. In addition or in the alternative, the surgical assemblies can include a cannulated drill and obturator for sliding engagement within an interior region of the cannulated drill. One or more of the surgical assemblies can be provided for delivery of a flowable or injectible osteoinductive composition into a desired treatment site. Embodiments of kits for treating pseudoarthrosis that include a combination of the surgical instruments and/or instrument assemblies described herein are also provided.
As disclosed above, in one aspect of the invention, surgical instruments may be advantageously utilized in a procedure for treating pseudoarthorosis. Embodiments of these instruments will be described first in order to facilitate the discussion herein of the methods of treating spinal pseudoarthrosis. In one embodiment, a surgical instrument includes an elongated channel-forming and delivery member such as a drill 10 as seen in FIGS. 1 and 2. Drill 10 comprises an elongated member 20 having a proximal end 21, a distal end 22, an exterior surface 23 and an inner surface 24. Distal end 22 has at least one bone cutting edge 26, and preferably about two to about four cutting edges for cutting bone. Alternately, the drill may include any device capable of forming a passageway or channel in or adjacent to the site of pseudoarthrosis, such as a piercing device, milling device, etc. Inner surface 24 defines a lumen 25 extending along the length of elongated member 20, typically from proximal end 21 to distal end 22. Lumen 25 is illustrated as a cylindrical channel having a first opening 11 adjacent to proximal end 21, and a second opening 12 proximate to distal end 22 permitting access through the interior of drill 10. Moreover, lumen 25 of elongated member 20 is sized to receive an obturator (not shown). In another embodiment, lumen 25 is sized to receive a guide wire, such as, a K-wire. The guide wire can be selected to be any desired diameter and/or length. The guide wire can be inserted into a treatment site to facilitate desired placement of drill 10 during treatment. Proximal end 21 of elongated member 20 is advantageously configured for mating with a syringe. Proximal end 21 of elongated member 20 may
therefore include, or otherwise define, a connector 27 that matingly engages the distal end of a syringe to proximal end 21 of elongated member 20. The connector may be formed integral with the elongated member or may be separately connected thereto, such as by use of press-fit threaded connectors, adhesives and any other securing methods or combinations thereof. A wide variety of connectors may be utilized, including luer-lock connectors, Moorse taper connectors and snap-lock connectors.
Figure 3 illustrates an alternative embodiment of a drill 10' for use in the present invention. Drill 10' is formed similar to drill 10 and like reference numbers with a prime are used to denote like elements. Drill 10' includes a plurality of apertures 28 extending through exterior surface 23' to inner surface 24'. Preferably, apertures 28 are provided in a desired size, number and location along a length of the drill 10'. In one embodiment, the apertures are sized and located to effectively deposit an osteoinductive material across a pseudoarthrotic region of the spine with minimal or no repositioning of the drill. In the illustrated embodiment a plurality of apertures 28 are located proximate to distal end 22'.
Referring now to FIGS. 4 and 5, one embodiment of a lumen-blocking device such as obturator 30 comprises an elongated member 40 having a proximal end 41, a distal end 42, an outer surface 43 and an inner surface 44. Inner surface 44 defines a lumen 45 that extends along the length of elongated member 40, typically from proximal end 41 to distal end 42. Obturator 30 may be advantageously designed and configured to conform to inner surface 24 of elongated member 20 of drills 10 and/or 10' and/or be slidably received within lumen 25 and/or 25'. Although obturator 30 may be variously shaped, in one form of the invention obturator 30 is cylindrical. For example, obturator 30 is slidably disposed in lumen 20 of drill 10 to provide assembly 35 as best seen in FIG. 6A and FIG. 6B. Obturator 30 can be sized and configured to inhibit material from entering the lumen of the drill during the drilling process.
In other forms of the invention, yet other drills may be utilized. Referring to FIG. 7, a drill 10" is shown. Drill 10" is formed similar to drill 10 and like reference numbers with a double prime are used to denote like elements. Drill 10" advantageously may have a built-in depth gauge 29. Depth gauge 29 can be movably secured to a portion of surface 23" that limits the drilling depth of drill 10". Depth gauge 29 may be positionable during surgery. For example, the surgeon can determine a desired depth to bore into a bone or pseudoarthrotic site using x-ray, Computer Tomography (CT), fluoroscopy or other techniques. The surgeon can then measure a distance from distal end 26" toward proximal end 21 " equal to the desired bore depth.
The surgeon can then position depth gauge 29 at a position 36 from the distal end of drill 10" equal to the desired bore depth. Depth gauge 29 can be secured in the desired position using a set screw, or other locking mechanism.
The drills and obturators described herein may be formed of biocompatible materials. In preferred forms of the invention, the drill and obturator may be formed from metallic materials, including stainless steel, titanium, and alloys thereof. Other suitable materials include nitinol, or other shape memory materials.
In another aspect of the invention, embodiments of surgical instrument assemblies are provided. Referring now to FIG. 8A, in one form of the invention, a surgical instrument assembly 50 includes drill 10 and syringe 60. While drill 10 is illustrated it is understood that any of drills 10, 10' and/or 10" can be included in the assembly. Syringe 60 may be any device capable of delivering an osteoinductive composition. In one embodiment, syringe 60 includes a barrel, or housing, 61 having a proximal end 62 and a distal end 63. Housing 61 defines a cavity, or chamber, 64 for retaining a composition to be delivered. Plunger 66 having a plunger head 67 is disposed in cavity 64 of syringe 60. Distal end 63 defines a connector portion 68, such as a luer-lock connector provided to relesably engage connector 27 of drill 10.
1 1
Referring additionally to FIG. 8B, distal end 63 of syringe 60 is matingly engaged to proximal end 21 of drill 10. When so engaged, chamber 64 of syringe 60 is in fluid communication with lumen 25 of drill 10 to form surgical instrument assembly 50. Syringe 60 may be formed of a material that does not react with osteoinductive compositions, such as polymeric materials, including metal, glass, and synthetic polymers, such as polyalkenes, including polyethylene, polypropylene, poly(vinyl chloride), and polystryrene. Referring to FIG. 8C, an alternative surgical instrument assembly is shown that includes drill 10 and syringe 60'. As above noted while drill 10 is illustrated in assembly 50' any of drills 10, 10' and 10" can be combined with syringe 60'. Syringe 60' is formed similar to syringe 60, and thus like reference numbers denote similar components but are denoted with a prime. Plunger 66' includes one or more threads 68 extending along a length of plunger shaft 69. Threads 68 can facilitate incremental adjustment of plunger 66 in chamber 64, and, consequently, facilitate withdrawing or expulsion of material into or out of chamber 64.
As seen in FIG. 9, in another embodiment, an elongated delivery member 70 fluidly connectable with an osteoinductive material delivery device includes an elongated member 71 having a proximal end 72, a distal end 73, an outer surface 74 and an inner surface 75. Inner surface 75 defines a lumen 76 extending along the length of elongated member 71, typically from proximal end 72 to distal end 73. In one embodiment, distal end 73 can be closed. Alternatively, distal end 73 can include one or more openings extending therethrough providing communication with lumen 76. Furthermore, elongated member 71 may have a plurality of apertures, or other openings or perforations, 78 extending through outer surface 74 anywhere along a length of elongated member 71 , such as adjacent to distal end 73. Proximal end 72 may have a connector 77 for matingly engaging a syringe and may be similar to the connectors 27 described above for the drill 10. In another form, the invention provides methods for treating pseudoarthrosis. The methods may be minimally invasive. For example, an