Abstract:
A frustum shaped body has an aperture in a top surface and a pair of first and second opposed apertures in a side surface, first and second horizontal internal channels connect both the first and second opposed apertures. A vertical channel from the top aperture connects with the first and second channels. After the body is inserted into a hole in a facet joint, compatible synthetic or biologic material is inserted into the vertical channel until the material exits from the first and second apertures in the side surface. At least one pair of flanges on a portion of an exterior side surface of the body acts as a detent to hold the body in place within the facet joint hole.

Description:
PRIOR APPLICATIONS 
       [0001]    This application is continuation of application Ser. No. 11/232,519, filed Sep. 22, 2005, which is a continuation-in-part from application Ser. No. 10/992,720, filed Nov. 22, 2004, now abandoned which is expressly incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to minimally invasive spine surgery and, more particularly, to using an arthroscopic type portal or open facet joint fusion surgical instrumentation for insertion of either pre-made, pre-shaped synthetic cortical bone or harvested and compacted iliac crest grafts, autologous or cadaveric allografts. The graft and fusion system is limited to the forty-eight facet joints located on the spine, C1-C2 through L5-S1. 
         [0004]    2. Description of the Prior Art 
         [0005]    In the United States alone, about 10% of the entire population will suffer from back pain sometime in the next twelve months. More people will contract back pain in the next year than any other injury or disease except the common cold and flu. About one-third will not recover and have to live with persistent, disabling symptoms. The number is cumulative year after year. 
         [0006]    One of the root causes of back pain, particularly the persistent and disabling kind, are facet joints, small joints located behind adjacent vertebrae in the spine that allow for spinal motion. 
         [0007]    Present surgical solutions available for the millions of people with facet joint dysfunctions are complex, invasive, pedicle screw based high-risk operations with prolonged recovery times, from 6 to 24 months, and uncertain outcomes. High risk equates to frequent litigation, which forces non-surgical symptomatic treatment while the disease or consequences of injury progressively worsen. Some of these efforts provide intervertebral fusion described in U.S. Pat. No. 6,485,518 and U.S. Patent Application Serial Number 2003/0032960. Numerous patents have been granted for general fusion of the spine that may or may not involve the facet joint by proximity or design. 
         [0008]    With the advent of new, safer and less invasive surgical techniques and technology, the growth of spine surgery now outpaces every other orthopedic surgery segment. Its growth is further fueled by an enormous demand. 
       SUMMARY OF THE INVENTION 
       [0009]    The use of pre-shaped, harvested or synthetic bone as a structural fixation for facet joint fusion offers three distinct advantages over pedicle or compression screws, which are presently used in facet fusion procedures; i.e., (1) using bone instead of metal allowing for natural bone ingrowth and a stronger, permanent fusion; and (2) the natural or synthetic graft cannot work its way loose over time, a concern with screw type fixation. 
         [0010]    The grafts and system are specifically designed for use in a minimum invasive or an arthroscopic type portal for stand-alone procedures and provide a stronger, unique and superior fusion when used as an adjunct to instrumented vertebral fusion by greatly reducing risk of facet joint pain resulting from persistent facet joint motion. 
         [0011]    The minimally invasive facet joint fusion for the treatment of a diseased or painful facet joint that is not appropriate for resurfacing or replacement, involves the use of instrumentation and autograft, cadaveric allograft or FDA approved pre-made, pre-shaped synthetic cortical bone graft for use in minimally invasive, outpatient, arthroscopic spine surgery or classic open surgery and, more specifically, to fuse spinal facet joints from C1-C2 through L5-S1. This system serves as a primary or a revision surgery. 
         [0012]    The present invention accomplishes a superior spinal facet joint fusion by providing a grafting alternative to facilitate fusion using arthroscopic portal or open surgical techniques of the C1-C2 through L5-S1 spinal facet joints. 
         [0013]    According to one broad aspect of the present invention, the arthroscopic facet joint fusion system comprises a punch or drill that creates a hole through both sides of the facet joint in a conical pattern. The hole is filled with either the patient&#39;s own harvested and compacted bone plug using iliac crest autograft, pre-made, pre-shaped cortical cadaveric allograft (the autograft or allograft formed by bone plug press or machining) or FDA approved pre-made, pre-shaped synthetic grafts. 
         [0014]    The punch or drill includes any number of components capable of performing the creation of a hole through both sides of the spinal facet joint using an arthroscope or similar portal to access the joint or during classic open surgery. By way of example only, the punch/drill includes a hand actuator that will create sufficient pressure to create a specific sized hole through both sides of the spinal facet joint using a mechanical arrangement similar to that of common pliers resized to work through an arthroscopic opening. Additionally, a drill guide can be placed and a specifically sized and shaped drill bit can be used to create the opening, either in a horizontal or vertical direction through the facet joint. 
         [0015]    The bone plug press (graft forming or compression instrument) includes any number of components capable of using harvested autograft, cadaveric allograft cortical bone or a synthetic alternative to match the bone tunnel made by the punch or drill. By way of example only, the bone plug press includes a mechanism similar to common pliers or a more standard hand press that will transfer sufficient force to form bone plugs by squeezing the handles together to form the bone plug and compress the bone or synthetic alternative to the proper density and shape. 
         [0016]    The impactor or tamp includes any number of components capable of pushing and compressing the bone plug into the bone tunnels. A suture or metallic overlay also can be applied to provide additional structural stability to the joint during graft incorporation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Many advantages of the present invention will be apparent to those skilled in the art with a reading of this specification in conjunction with the attached drawings, wherein like reference numerals are applied to like elements and wherein: 
           [0018]      FIG. 1  shows a frustum shaped bone plug of this invention for employment in a facet joint fusion; 
           [0019]      FIG. 2  shows a tapered drill used to prepare for the bone plug; 
           [0020]      FIG. 3  shows a hole prepared for the bone plug; 
           [0021]      FIG. 4  shows a bone plug inserted in the hole of  FIG. 3  and with an application tube for inserting synthetic or biologic material; 
           [0022]      FIG. 5 , is a cross-section along line  5 - 5  of  FIG. 4 ; 
           [0023]      FIG. 6  is a cross-section along line  6 - 6  of  FIG. 4 ; 
           [0024]      FIG. 7  is a cross-section according to  FIG. 6  showing synthetic or biologic material cementing the bone plug in place; 
           [0025]      FIG. 8  shows a first alternative frustum shaped bone plug; 
           [0026]      FIG. 9  shows a cross-section of the frustum shaped bone plug of  FIG. 8  along lines  9 - 9 ; and 
           [0027]      FIG. 10  shows a second alternative frustum shaped bone plug. 
           [0028]      FIG. 11  shows an instrument and arthroscopic portal according to an embodiment of the invention. 
           [0029]      FIG. 12  shows an instrument and arthroscopic portal according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Referring to  FIG. 1 , the bone plug of this invention is an inverted frustum shaped device  10  having a vertical central channel  12  for insertion of a synthetic or biologic material to assist in fusing the bone plug  10  in place in a spinal joint  15 . The bone plug  10  has multiple side parts  14  and  16  for excretion of the synthetic or biologic material from the central channel  12 . A pair of opposed flanges  18  and  20  on the same plane partially circumvent the bone plug  10  near bottom end  22  having a smaller diameter than the top end  24 . 
         [0031]    In order to fuse a spinal facet joint, a tapered drill  26 , shown in  FIG. 2 , is employed to prepare a hole  28  shown in  FIG. 3  between two bones  30  and  32 . A drill guide  31  may be used to guide the tapered drill  26  to prepare the hole  28  in the correct location. Drill guide  31  may be secured to the facet joint by teeth  33  to prevent displacement during hole preparation. As seen in  FIG. 4 , an application tube  34  is inserted in channel  12  to permit insertion of a synthetic or biologic material  36  into bone plug  10 . The biologic material  36  flows down channel  12  as shown in  FIG. 5 , and excess biologic material flows out of side parts  14  and  16  through channels  42  and  44 , respectively, into a space  38  between the bones  30  and  32 , and an exterior side wall  40  of the bone plug  10 . The flanges  18  and  20  act as detents to hold the bone plug  10  in place within hole  28 . As seen further in  FIG. 7 , the biologic material  36  flows outwardly from openings  14  and  16  into a space  38  to cement the plug  10  in place. 
         [0032]    An alternative plug  10   a  is shown in  FIGS. 8 and 9 . A central channel  12   a  feeds biologic material to side channels  46 ,  42  and  44   a . In like manner, biologic material  36  flows out through openings  52 ,  14   a  and  16   a  and promotes bonding to the bone. A second parallel pair of flanges  48  and  50  are added to flanges  18   a  and  20  a to increase the strength of the plug  10   a  in the hole  28 . Side wall  40   a  in like manner to plug  10  is narrower in diameter at a bottom end  22   a  than its top end  24   a.    
         [0033]    If the joint is determined to be too badly damaged or diseased for present replacement methods or prospective methods such as facet joint hemi-arthroplasty, minimally invasive facet joint fusion is prospectively a superior alternative for three primary reasons: 
         [0034]    1. It is minimally invasive surgery that can be performed in an outpatient setting as opposed to major surgery performed in a hospital. This procedure can also be performed during open surgery if the facet joints need to be fused as determined by a physician particularly in conjunction with instrumented vertebral fusion; 
         [0035]    2. Recovery times are estimated to be a few weeks as opposed to 6 to 12 months; and 
         [0036]    3. It takes full advantage of advances in biomaterials and synthetic alternatives. 
         [0037]    The present invention is directed at overcoming, or at least improving upon, the disadvantages of the prior art by achieving the following: 
         [0038]    Reversal of the cost/benefit ratio of present procedures versus the invention; 
         [0039]    A minimally invasive procedure versus major open surgery; 
         [0040]    Outpatient versus inpatient surgery (about 20 minutes per joint versus hours). Note: this procedure may also be performed during open surgery at the discretion of the physician; 
         [0041]    Can be used to augment present open fusion techniques to lessen the need for bone stimulation especially in high risk groups such as smokers and multi-level cases; 
         [0042]    Reduced morbidity; 
         [0043]    Reduced blood loss; 
         [0044]    Reduced time under anesthesia; 
         [0045]    Reduced risk; 
         [0046]    Recovery time dramatically reduced; 
         [0047]    Minimal scarring that decreases the risk of failed back syndrome and improves revision surgery outcome; 
         [0048]    Reduced risk of post operative infection by significantly reducing operating room time and soft tissue destruction; 
         [0049]    No preclusion of other surgical or non-invasive treatment options; and, 
         [0050]    Projected high success rate by utilizing accepted arthroscopic procedures employing a new technique and taking advantage of either existing cortical bone harvesting procedures in combination with unique instrumentation to shape and prepare the bone or new pre-shaped, pre-made synthetic cortical bone alternatives as they are made generally available by FDA approval. 
         [0051]    It is anticipated that the availability of this system and graft alternatives will dramatically increase the number of surgeries performed because they offer the first safe outpatient surgical solution to the predominant cause of spinal joint pain. It is expected that virtually all patients receiving this procedure will be able to walk out the same day and be fully functional within a few weeks. Present surgical solutions require hospitalization of about three days and six to twenty-four months recovery. 
         [0052]    Aside from the obvious positive clinical outcome, the significant favorable financial impact on disability, worker&#39;s compensation and health care insurers is considerable. 
         [0053]    Spinal facet implant units are calculated per joint. Each patient has two joints per spinal segment and twenty-four segments, C1-C2 through L5-S1 for a total of forty-eight facet joints. Each surgery is likely to involve multiple joints. 
         [0054]    The present invention is directed at overcoming, or at least improving upon, the disadvantages of the prior art. 
         [0055]    In inserting the plug  10 , the tapered drill is specifically used through an arthroscopic type portal allowing access to the joint through a small incision and progressive dilation of the intervening soft tissue. The instrument design does not preclude its use in a classic open surgery or by access to the facet joint through an otherwise limited incision. The opening  28  is marginally smaller than the bone plug  10  to create proper fixation of the plug  10  and the joint. 
         [0056]    Referring again to  FIGS. 1 and 8 , a fused facet joint plug  10 ,  10   a  or  10   b  is shown with one shaped autograft, cadaveric allograft or FDA approved synthetic pre-made, pre-shaped cortical bone plug. The anterior end  22  or  22   a  of the plug  10  or  10   a  is 3-8 mm and the posterior end  24  or  24   a  of the plug  10 ,  10   a  or  10   b  is 4-12 mm in diameter in a frustum shape with the wider portion located in the posterior portion to facilitate fixation during bone graft incorporation. The procedure is envisioned to require only one bone plug per facet joint and two per level. Permanent fixation occurs when bone in-growth occurs into the joint itself and into the plug over time. 
         [0057]    The frustum shaped bone graft  10   b , as shown in  FIG. 10 , can be employed when no additional biologic material is required. 
         [0058]      FIG. 11  illustrates a bone punch instrument as an embodiment of the invention shown without representation of a press accessory, which can be attached to the punch tips  4  and used to press a bone plug into place. The instrument is specifically invented to be used through an arthroscopic type portal  1  allowing access to the joint through a small incision and progressive dilation of the intervening soft tissue. In this embodiment, arthroscopic type portal  1  comprises a cylindrical tube configured to provide access to a facet joint during surgery. The arthroscopic type portal  1  has an outer surface that prevents the encroachment of surrounding biological material into the surgical site at the facet joint and has an inner surface that forms a substantially cylindrical space that provides access to the facet joint for the surgical tools. The instrument design does not preclude its use in a classic open surgery or by access to the facet joint through an otherwise limited incision. A separating handle  2  is specifically designed to provide sufficient mechanical advantage to the punch tips  4 . Punch tips of different sizes to create an appropriate opening to receive the sized bone plug selected by a physician. The opening is marginally smaller than the bone plug to create proper fixation of the plug and the joint. Mechanical advantage created by pressure on the handle is transferred to the punch tips using an “X” type joint  3 . 
         [0059]      FIG. 12  illustrates a specially designed osteotome as an embodiment of the invention, which accesses the facet joint through an arthroscopic type portal  5  and is used to make a thin slice into the bone on each of the inner surfaces of the joint to prepare the surface to heal together in a permanent fusion. The osteotome is equipped with a specifically sized single use blade  6  shown in situ in the correct aspect into a facet joint  7 . The osteotome is impacted with a slap-hammer  8  to make the cuts and is properly positioned using a loop  9  on the osteotome shaft. A protective stop  10  is provided to ensure that the osteotome blade does not penetrate to an unsafe depth. 
         [0060]    Other equivalent elements can be substituted for the elements disclosed herein to produce substantially the same results in substantially the same way.