Abstract:
An instrument for use in preparing a graft. The instrument includes at least one cutting portion configured to resect a graft section from the graft. The instrument also includes a drive portion operably coupled to the cutting portion and configured to receive a rotational force. At least one reaming portion is positioned proximally to the cutting portion, the reaming portion is configured to ream a surface of the graft. The reaming portion and the cutting portion are positioned with respect to each other such that when the instrument is positioned against the graft and the rotational force is applied to the drive portion, the cutting section rotationally forms the graft section from the graft and the reaming portion rotationally reams a proximal section of the graft.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the field of orthopedics, and, more particularly, to glenoid component apparatuses for shoulder arthroplasty and methods for using them. 
       BACKGROUND 
       [0002]    In the shoulder, a person&#39;s glenoid fossa may become worn, causing severe shoulder pain and limiting the range of motion of the patient&#39;s shoulder joint. Shoulder arthroplasty may be performed to alleviate such pain and increase the patient&#39;s range of motion. Arthroplasty is the surgical replacement of one or more bone structures of a joint with one or more prostheses. 
         [0003]    Shoulder arthroplasty often involves replacement of the glenoid fossa of the scapula with a prosthetic glenoid component. The conventional glenoid component typically provides a generally laterally or outwardly facing generally concave bearing surface against which a prosthetic humeral head (or, alternatively, the spared natural humeral head in the case of a glenoid hemi-arthroplasty) may bear during operation of the joint. The conventional glenoid component typically also includes a generally medially or inwardly projecting stem for fixing the glenoid component in a cavity constructed by suitably resecting the glenoid fossa and suitably resecting cancellous bone from the glenoid vault. 
         [0004]    However, in patients suffering from Cuff Tear Arthropathy (CTA), a standard shoulder replacement is not an option. In such cases, a reverse shoulder is often used. A reverse shoulder, as shown in  FIGS. 1 and 2 , includes inserting a metaglene  10  into the glenoid fossa  12 . A glenosphere  14  is coupled to the metaglene. The glenosphere  14  articulates against a cup  16  that is attached to a stem  18 , inserted into a humerus  20 . These types of procedures are generically referred to as reverse shoulder arthroplasty. 
         [0005]    In some forms of CTA, the glenoid vault may be severely eroded. In such instances, the metaglene  10  cannot properly fit on the glenoid fossa  12 . When dealing with those types of situations, surgeons may use bone graft to fill in the space in the glenoid vault. In some instances, the bone graft may be formed from the resected humeral head. Currently, surgeons may use allograft or bone resected from other parts of the body such as the resected humeral head or portions of the femur. In these types of resections, the surgeon must resect the bone graft (or allograft) from the humeral head using tools created for other uses. This results in poorly shaped bone grafts and requires a lot of extra time in the operating room. 
         [0006]    Therefore, there is a need for an instrument that can efficiently and accurately resect and shape a properly shaped bone graft or allograft. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one embodiment, the present invention is an instrument including at least one cutting portion configured to resect a graft section from the graft. The instrument also includes a drive portion operably coupled to the cutting portion and configured to receive a rotational force. At least one reaming portion is positioned proximally to the cutting portion, the reaming portion is configured to ream a surface of the graft. The reaming portion and the cutting portion are positioned with respect to each other such that when the instrument is positioned against the graft and the rotational force is applied to the drive portion, the cutting section rotationally forms the graft section from the graft and the reaming portion rotationally reams a proximal section of the graft. 
         [0008]    According to another embodiment of the present invention, a kit is provided and the kit includes a power extension adapted to couple to a power tool and having a power transfer portion at one end. The kit also includes an instrument having at least one cutting portion configured to resect a graft section from the graft. The instrument further includes a drive portion operably coupled to the cutting portion and configured to receive a rotational force. At least one reaming portion is positioned proximally to the cutting portion, the reaming portion configured to ream a surface of the graft. A drilling portion is also part of the instrument and is configured to rotationally create a bore in the graft. The drilling portion is positioned distally from the reaming portion and is operably coupled to the drive portion. The reaming portion and cutting portion are positioned with respect to each other such that when the instrument is positioned against the graft and the rotational force is applied, the cutting portion rotationally forms the graft section and the reaming portion rotationally reams a proximal section of the graft section. Also, the drive portion is adapted to be coupled to the power transfer portion of the power extension. 
         [0009]    According to yet another embodiment of the present invention, a method for preparing a graft section from a sample is provided. An instrument is used, the instrument having at least one cutting portion configured to resect the graft section from the bone sample, at least one reaming portion positioned proximally to the cutting portion, the reaming portion configured to ream a surface of the graft section, and a drilling portion configured to rotationally create a bore in the graft, the drilling portion being positioned distally from the reaming portion. The sample is obtained and instrument is positioned adjacent the sample. The cutting portion cuts a section of the sample, while the proximal section of the sample is reamed and a bore is drilled in the sample. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a partial cut-away view of a reverse shoulder implant as known in the prior art. 
           [0011]      FIG. 2  is a perspective view of a metaglene as known in the prior art. 
           [0012]      FIG. 3  is a partial cut-away view of an instrument according to one embodiment of the present invention. 
           [0013]      FIG. 4  is a side view of the instrument of  FIG. 3 . 
           [0014]      FIG. 5  is a bottom view of the instrument of  FIG. 3 . 
           [0015]      FIG. 6  is a partial cut-away view of the instrument of  FIG. 3 . 
           [0016]      FIG. 7  is a side view of a power extension according to one embodiment of the present invention. 
           [0017]      FIG. 8  is a combination of the power extension of  FIG. 7  and the instrument of  FIG. 3 . 
           [0018]      FIG. 9  is another view of the combination of  FIG. 8 . 
           [0019]      FIG. 10  is a flow chart illustrating a method of using the instrument according to one embodiment of the present invention. 
           [0020]      FIG. 11  is a plan view of a resected humeral head. 
           [0021]      FIG. 12  is a plan view of an assembled instrument, power extension and guide pin according to one embodiment of the present invention. 
           [0022]      FIG. 13  is a plan view of the assembled instrument of  FIG. 12  adjacent a humeral head. 
           [0023]      FIG. 14  is a plan view of the assembled instrument of  FIG. 12  cutting through the humeral head. 
           [0024]      FIG. 15  is a plan view of the humeral head after the instrument according to one embodiment of the present invention has been used. 
           [0025]      FIG. 16  is a plan view of the resulting resected bone graft according to one embodiment of the present invention. 
           [0026]      FIG. 17  is a perspective view of the resulting resected bone graft attached to a metaglene according to one embodiment of the present invention. 
           [0027]      FIG. 18  is a perspective view of the resulting resected bone graft of  FIG. 17  attached to a metaglene and a head. 
           [0028]      FIG. 19  an instrument to aid in reaming the resected bone graft according to one embodiment of the present invention is shown. 
           [0029]      FIG. 20  is a perspective view of the instrument of  FIG. 19 . 
           [0030]      FIG. 21  is another perspective view of the instrument of  FIG. 20 . 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    Like reference numerals refer to like parts throughout the following description and the accompanying drawings. 
         [0032]    With reference to  FIGS. 3-6 , an instrument  40  is shown for preparing a bone graft from a bone sample. In this application the term “bone sample” is meant to include any type of resected bone or allograft. The instrument includes a drive portion  42 , a reaming portion  44 , a cutting portion  46 , and a drill or boring portion  48 . The drive portion  42  in this embodiment is a hexagonally shaped bore  43  defined in the reaming portion  44 . The instrument includes a body portion  49  that defines the hexagonally shaped bore  43 . The reaming portion  44 , cutting portion  46  and drill portion  48  all extend distally from the body portion  49 . 
         [0033]    A number of reaming fins  50  extend from the reaming portion  44  toward the drill portion  48 . The reaming fins  50  curve proximally and outwardly from the lower central portion of the reaming portion  44  to the outer periphery of the cutting portion  46 . The reaming fins  50  include an arcuate leading edge  52 . 
         [0034]    The cutting portion  46  includes a smooth cylindrical wall  54  surrounding the reaming portion  44 . In the embodiment illustrated in  FIGS. 3-6 , the cylindrical wall  54  is smooth and includes an edge  56  at the distal end of the device  40 . The edge  56  includes a plurality of cutting teeth  58 . In the illustrated embodiment, only the edge  56  includes cutting teeth  58 . In other embodiments, the cylindrical wall  54  may not be smooth, it may include cutting teeth  58  on the outside of the cylindrical wall  54 . In other embodiments, the cutting teeth  58  may be located on the interior of the cylindrical wall  54 . 
         [0035]    The drilling portion  48 , which may include a drill bit, extends away from the reaming portion  44  to a distal tip  62 . Two flutes  64  and  66  extend helically about the drilling portion  48  between the reaming portion  44  and the distal tip  62 . A guide bore  68  extends from the distal tip  62  to the drive portion  42 . In the illustrated embodiment, the distal tip  62  does not extend past the edge  56  of the cutting portion  46 . In other embodiments, the distal tip  62  may extend past the edge  56  of the cutting portion  46 . 
         [0036]    As discussed in further detail below, a kit may include one or more instruments  40  along with various instrumentation to facilitate use of the instrument  40 . By way of example,  FIG. 7  depicts a power extension  70  that may be included in the kit. The power extension  70  includes a power receiving portion  72  and a power transfer portion  74 . The power receiving portion  72  is sized and configured to couple with a power tool and includes a pair of opposing power receiving flats  76  and a pair of coupling grooves  78  and  80  which extend about the power receiving portion  72  between the power receiving flats  76 . 
         [0037]    The power transfer portion  74  is shaped to be complimentary to the drive portion  42 . In the embodiment of  FIGS. 7 and 8 , the power transfer portion  74  is thus a hexagonally shaped protrusion sized to fit within the drive portion  42 . A guide bore  82  extends from the distal tip of the power transfer portion  74  to the proximal end of the power receiving portion  72 . 
         [0038]    To couple the instrument  40  with the power extension  70 , the power transfer portion  74  is aligned with the drive portion  42  as shown in  FIG. 8 . The instrument  40  with the power extension  70  are then moved toward each other such that the power transfer portion  74  enters into the drive portion  42  resulting in the configuration of  FIG. 9 . In  FIG. 9 , the guide bore  68  of the instrument  40  is aligned with the guide bore  82  of the power extension  70 . 
         [0039]    A kit including the instrument  40  and the power extension  70  may be used in preparing a bone graft from a resected humeral shoulder  100  ( FIG. 11 ) in accordance with the procedure illustrated in  FIG. 10 . Initially, at step s 200 , the surgeon or other hospital staff begins the procedure by preparing the bone sample, which may be allograft or bone graft. In the illustrated embodiment, a humeral head will be used. However, in other embodiments, allograft or bone grafts from other sites of the body may be used. In this embodiment, since a humeral head  100  ( FIG. 11 ) is used, at step s 200  the humeral head is resected from the humerus. A guide wire  102  ( FIG. 13 ), which may be provided in a kit along with other instrumentation used in the procedure, may be positioned on the humeral head  100  at step s 202 . In some embodiments, a guide wire may not be used and this step may be skipped. In embodiments using a guide wire, the positioning of the guide wire may be computer aided. The guide wire  102  is put into place such that the instrument  40  will be able to get a complete wedge of bone material. 
         [0040]    At step s 204 , the assembled power extension  70  and instrument  40  are slid over the guide wire. The guide wire  102  extends through the guide bore  68  of the instrument  40  and the guide bore  82  of the power extension  70  as shown in  FIG. 13 . The guide wire  102  thus guides the power extension  70  and the instrument  40 . In some embodiments, the instrument  40  may be inserted onto the guide wire  102  prior to the power extension  70  being assembled to the instrument  40 . In that instance, the instrument  40  is first inserted over the guide wire  102  and then the power extension  70  is inserted over the guide wire  102 . Some rotation of the power extension  70  may be required to align the power transfer portion  74  with the drive portion  42  of the instrument  40  to allow coupling of the power extension to the instrument. 
         [0041]    A rotary tool (not shown) is then coupled to the instrument  40  at step s 206 . In some embodiments, a rotary tool may be directly coupled to the instrument  40 . In this example, the power extension  70  is coupled to the instrument  40  as described above. Thus, the rotary tool is coupled to the power receiving portion  72  of the power extension  70  so as to be indirectly coupled to the instrument  40 . 
         [0042]    Power is then applied to the rotary tool causing the rotary tool to rotate the power extension  70 . Rotary force is transferred to the drive portion  42  of the instrument  40  through the power transfer portion  74 . As the instrument  40  initially rotates about the guide wire  102 , the reaming portion  44 , the cutting portion  46 , and the drilling portion  48  all contact the resected humeral head  100  and begins to cut a bone graft  104  from the head at step s 208 . The cutting, drilling and reaming all occur as a single step, reducing time in the operating room. As the cutting portion  46  cuts the bone graft  104 , the drilling portion  48  then engages the bone graft  104  and begins boring a hole over the guide wire  102 . As the bone graft  104  is created and a hole is formed in the bone graft  104  by the drilling portion  48 , the instrument  40  is guided by the guide wire  102  such that the reaming fins  50  come into contact with a proximal portion of the bone graft  104  as depicted in  FIG. 14 . Continued rotation of the instrument  40  with the rotary tool thus causes simultaneous reaming of the bone graft  104  with the reaming fins  50  and boring of the bone graft  104  with the drilling portion  48 . 
         [0043]    The power tool is de-energized and disconnected at step s 210 . At step s 208 , a cutting guide or other tool may be used to disengage the bone graft  104  from the humeral head  100 , leaving the humeral head  100  as shown in  FIG. 15 . The completely removed bone graft  104  is illustrated in  FIG. 16 . 
         [0044]    The size of the drilling portion  48 , both in length and diameter, is selected to be complimentary to the size of a center peg  152  of a metaglene component  154  (FIG.  17 ). Thus, upon completion of the reaming, the bore formed by the drilling section is sized to receive the center peg  152 . 
         [0045]    The bone graft  104 , as shown in  FIG. 16 , is completely cut from the humeral head.  FIG. 17  illustrates the bone graft  104  as it is coupled to the metaglene component  154 . A head  155  is then placed on the metaglene  154  as shown in  FIG. 18  and the combination of the bone graft  104 , the metaglene component  154 , and head  155  are then fit into the glenoid. The rest of the reverse shoulder may then be assembled as is known in the art. 
         [0046]    The above method describes using the instrument  40  to prepare a portion of bone graft (or allograft) such that the reaming portion  44  is configured to prepare a surface that will mate with the back side of the metaglene component  154 . In other embodiments, the reaming portion  44  may be used to prepare a surface that will mate with the glenoid. In other words, the bone graft  104  will have two opposing sides  156 ,  158  as shown in  FIG. 16 . One of the opposing sides  156  is configured to abut the metaglene component  154  and the other of the opposing sides  158  is configured to abut the glenoid. The reaming portion  44  of the instrument  40  may be configured to prepare either of the two opposing sides  156 ,  158 . The other side must be prepared using a different instrument, such as a cutting guide or reamer. 
         [0047]    Turning now to  FIG. 19 , one instrument  160  for aiding in the reaming is shown. In this embodiment, the instrument  160  is a holder. As stated above, the instrument  40  is used to prepare one side (in this embodiment, the side  158  that will abut the glenoid, although it may be either side). After the bone graft  104  is removed from the original head  100 , the bone graft  104  is inserted into the holder  160 . The holder  160  includes a cylinder  162  sized and shaped to hold the prepared bone graft  104 . The cylinder  162  may include slits  164 , which will be described in more detail below. 
         [0048]    As shown in  FIG. 20 , the holder  160  includes flanges  166  that extend from the inside of the cylindrical wall  162 . The flanges  166  include spikes  168 . The spikes  168  extend out from the flanges  166  and are used to grip the bone graft  104  into place. The flanges  166  will define openings  170  between them. The holder  160  also includes a punch  172 , having a sliding portion  174  and an extending portion  176  extending distally from the sliding portion. In this embodiment, the extending portion  176  includes a plurality of extending walls  178  that fit within the openings  170  of the cylinder  162 . 
         [0049]    Once the bone graft  104  is securely in place, a reamer (not shown) may be used to ream the other side  156  of the bone graft  104 . The reamer is used to prepare the other side  156  of the bone graft  104  to abut the metaglene component  154  ( FIG. 17 ). The slits  164  may be used as a visual aid in the reaming process. In other words, the user could view the reamer through the slits  164  and ensure that the reamer is reaming to the correct depth. After the other side  156  of the bone graft  104  is prepared, the punch  172  is slid down the holder  160 , such that the extending walls  178  slide through the openings  170  (shown in  FIG. 21 ) and push the bone graft  104  out of the holder  160 . A completely formed bone graft  104  is now ready for use. 
         [0050]    The foregoing description of the invention is illustrative only, and is not intended to limit the scope of the invention to the precise terms set forth. Further, although the invention has been described in detail with reference to certain illustrative embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.