Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a continuation-in-part of co-pending application Ser. No. 09/558,044, filed Apr. 26, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to total hip arthroplasty, and, more particularly, to a method and apparatus for performing a minimally invasive total hip arthroplasty.  
           [0004]    2. Description of the Related Art  
           [0005]    Orthopaedic procedures for the replacement of all, or a portion of, a patient&#39;s joint have been developed over the last 30 years. Currently, the procedures used to prepare the bone and seat the implants are generally referred to as open procedures. For the purpose of this discussion, the term open procedure will refer to a procedure wherein an incision is made through the skin and underlying tissue to fully expose a large portion of the particular joint surface. In the case of a total hip arthroplasty, the typical incision required is approximately 25 centimeters (10 inches) long. After the initial incision in the skin, the internal wound may be enlarged in order to fully expose the areas to be prepared. While this approach provides surgeons with an excellent view of the bone surface, the underlying damage to the soft tissue, including the muscles, can lengthen a patient&#39;s rehabilitation time after surgery. While the implants may be well fixed at the time of surgery, it may be several weeks or perhaps months before the soft tissues violated during surgery can be fully healed.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention provides an improved method and apparatus for performing a minimally invasive total hip arthroplasty. A total hip arthroplasty can be performed in accordance with the teachings of the current invention utilizing two incisions with the size of each of the wounds developed on the surface being substantially constant throughout the depth of the wound. The first incision is an anterior incision approximately 3.75-5 centimeters (1.5-2 inches) in length made in line with the femoral neck and the central axis of the acetabulum. The second incision is a posterior incision approximately 2.5-3.75 centimeters (1-1.5 inches) positioned to be generally in axial alignment with the femoral shaft.  
           [0007]    The femoral head is severed from the femoral shaft and removed through the anterior incision. The acetabular cup is placed in the acetabulum through the anterior incision, while the posterior incision is used to prepare the femoral shaft to receive a femoral stem. A femoral stem is inserted through the posterior incision and positioned in the femoral shaft. Procedures performed through the posterior incision may be observed through the anterior incision and vice versa.  
           [0008]    For the purpose of the following discussion, a total hip arthroplasty is defined as a replacement of the femoral head with or without the use of a separate acetabular component. The specific designs which can be utilized in accordance with the present invention include a total hip replacement and a bipolar or monopolar endo prosthesis. The technique is suitable for cemented or cementless anchorage of the components.  
           [0009]    The invention, in one form thereof, comprises a method of performing a total hip arthroplasty. The method of this form of the current invention includes the steps of: making an anterior incision, making a posterior incision, preparing an acetabulum to receive an acetabular cup through the anterior incision, seating an acetabular cup in the acetabulum through the anterior incision, preparing a femur to receive a femoral stem, and seating the femoral stem in the femur.  
           [0010]    The invention, in another form thereof, comprises a method of performing a total hip arthroplasty. The method of this form of the current invention includes the steps of: preparing a femur to receive a femoral stem, placing a protective bag over the femoral stem, and seating the femoral stem in the femur.  
           [0011]    The invention, in another form thereof, comprises a method of performing a total hip arthroplasty. The method of this form of the current invention includes the steps of: placing the patient in supine position; palpating the femoral neck and making an anterior incision of about 3.75-5 centimeters (1.5-2 inches) in line with the femoral neck and the central axis of the acetabulum; performing a blunt dissection of the muscle exposed by the anterior incision to expose the capsule of the hip joint; incising the capsule of the hip joint; retracting a portion of the capsule to visually expose the femoral neck; utilizing an osteotomy guide to mark a cut path along which a cut will be made to remove the femoral head and a portion of the femoral neck; cutting along the cut path; incising the ligamentum teres femoris; in situ morselizing the cut away femoral head and neck as necessary for removal through the anterior incision; removing the morsels of the femoral neck and head through the anterior incision; reaming the acetabulum; seating the appropriate acetabular cup in the reamed acetabulum; inserting a curved awl having a substantially straight distal end into the anterior incision; aligning the distal end of the awl with the femoral axis; palpating the distal end of the awl and making a posterior incision having a length of about 2.5-3.75 centimeters (1-1.5 inches) at the location of the distal end of the awl; performing a blunt dissection to provide an access through the posterior incision to the femoral shaft; threading a retractor into the recess formed between the posterior incision and the femoral shaft; passing a guide wire through the retractor and into the cancellous bone of the femoral shaft; positioning the guide wire in the cannula of a femoral reamer; reaming the femoral shaft with the femoral reamer using the guide wire to locate the cancellous bone of the femur; observing the reaming activity through the anterior incision; removing the femoral reamer; utilizing the guide wire to guide a rasp to the femoral shaft; positioning the rasp in the femoral shaft while observing through the anterior incision; removing the guide wire; removing the retractor from the posterior incision; positioning a trial acetabular liner in the acetabular cup through the anterior incision; affixing a provisional neck to the rasp through the anterior incision; affixing a provisional head to the provisional neck through the anterior incision; performing a trial reduction with the trial acetabular liner, provisional neck and provisional head in place; dislocating the provisional head; removing the trial acetabular liner through the anterior incision; removing the provisional neck and head through the anterior incision; removing the rasp through the posterior incision; seating a final acetabular liner in the acetabular cup through the anterior incision; inserting a femoral implant through the posterior incision; inserting a final femoral head through the anterior incision; affixing the final femoral head to the femoral implant; reducing the hip; and closing the incisions.  
           [0012]    In one form of the current invention, the step of positioning a rasp in the femoral shaft comprises: locking the rasp to a rasp handle having a cannular insertion member with a distal rasp engagement guide and an elongate aperture sized to accommodate a flexible cable, an engagement slot for selectively engaging an end of the flexible cable, a selectively actuatable grip operable to tension the flexible cable, a lock for selectively locking the grip in a position to tension the flexible cable, and an impact surface for receiving blows to place or remove the rasp; positioning the guide wire in a cannula of the rasp and the cannula of the rasp handle; guiding the rasp and the cannular insertion member through the posterior retractor to a proximal end of the femoral shaft using the guide wire; striking the impact surface to position the rasp within the femoral shaft; unlocking the grip; releasing the flexible cable from the engagement slot; and removing the rasp handle.  
           [0013]    In one form of the current invention, the step of locking the rasp to a rasp handle comprises: engaging a distal end of the flexible cable in the rasp; inserting the flexible cable through the elongate aperture of the rasp handle; guiding the distal rasp engagement guide into a rasp engagement guide receiving portion on the rasp; engaging the proximal end of the flexible cable in the engagement slot; and tensioning the flexible cable.  
           [0014]    In one form of the current invention, the step of removing the rasp from the femoral shaft comprises: reinserting the flexible cable through the elongate aperture of the cannular insertion member (the flexible cable remains engaged with the rasp placed in the femur and protrudes from the posterior wound); reinserting the cannular insertion member through the posterior retractor; guiding the distal rasp engagement guide into the rasp engagement receiving portion on the rasp; engaging the proximal end of the flexible cable in the engagement slot; tensioning the flexible cable; and impacting the impact surface to remove the rasp from the femoral shaft.  
           [0015]    The invention, in another form thereof, comprises a method of removing a femoral neck and head. The method of this form of the current invention includes the steps of: making an anterior incision in line with the femoral neck; providing an osteotomy guide having a handle and with an alignment portion and a cut guide affixed to the handle; aligning the alignment portion with the femoral axis, marking a cut path defined by the cut guide, and cutting along the cut path to remove a cut portion comprising a portion of the femoral neck and the femoral head.  
           [0016]    The invention, in another form thereof, comprises a method of making a posterior incision aligned with a longitudinal axis of the femur. The method of this form of the current invention includes the steps of making an anterior incision aligned with the femoral neck, providing an awl having a handle and a curved awl shaft having a distal end, aligning the distal end with the longitudinal axis of the femur, palpating a location of the distal end of the awl, and making a posterior incision at the location of the distal end of the awl.  
           [0017]    The invention, in another form thereof, comprises a method of preparing a femur to receive a femoral implant. The method of this form of the current invention includes the steps of: removing the femoral head and neck as necessary, making a posterior incision of approximately 2.5-3.75 cm which is substantially aligned with the central axis of the femoral shaft, performing a blunt dissection to provide an access through the posterior incision to expose the femoral shaft, inserting a retractor comprising a tunnel sized for insertion through the access into the access, and preparing the femur to receive a femoral implant through the retractor.  
           [0018]    The invention, in another form thereof, comprises an osteotomy guide having a handle allowing use of the osteotomy guide a distance from a femur as well as an alignment portion and a cut guide affixed to the handle.  
           [0019]    The invention, in another form thereof, comprises an awl having a handle and an awl shaft with a distal end. The distal end of the awl shaft is adapted to be inserted into an anterior incision and aligned with the longitudinal axis of a femur to locate a posterior incision operable to expose a proximal end of the femur.  
           [0020]    The invention, in another form thereof, comprises a retractor formed of a tunnel sized for insertion through an access leading to the femoral shaft in a body.  
           [0021]    The invention, in another form thereof, comprises a rasp handle having an insertion member with engagement means for selectively engaging a cable which is affixable to a rasp. In one form of the current invention, the engagement means comprises an engagement slot for selectively engaging the cable.  
           [0022]    The invention, in another form thereof, comprises a provisional femoral neck apparatus including a provisional femoral neck having a hollow, substantially cylidrical body. A spring biased locking piston is provided and housed within said hollow cylindrical body. The locking piston includes a tapered body portion. Application of a radial force to the tapered body portion moves the locking piston against the biasing force of the spring. The blades of a forceps may be utilized to apply the radial force to the tapered portion of the locking piston.  
           [0023]    The invention, in another form thereof, comprises a provisional prosthetic femoral neck having a guide surface and a provisional femoral stem including a mate to the guide surface. The guide surface is piloted to the mate to join the femoral neck and the femoral stem. In one form of the current invention, the femoral neck is substantially cylindrical and is piloted to the femoral stem in a radial direction.  
           [0024]    The apparatus and method of the current invention advantageously allow a total hip arthroplasty to be performed in a minimally invasive way, which hastens patient recovery. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:  
         [0026]    [0026]FIG. 1 is a side elevational view of a patient illustrating a pair of incisions made according to the current invention as well as the incision utilized in prior art procedures;  
         [0027]    [0027]FIG. 2 is an anterior elevational view of a hip joint illustrating the femoral neck axis;  
         [0028]    [0028]FIG. 2A is an anterior elevational view illustrating the capsule of the hip joint;  
         [0029]    [0029]FIG. 3 is an anterior elevational view of the femoral neck exposed by incising the hip capsule;  
         [0030]    [0030]FIG. 4 is an anterior elevational view of the femoral neck with an osteotomy guide of one form of the current invention operably positioned to designate a cut line thereon;  
         [0031]    [0031]FIG. 5A is a side elevational view of an alternative embodiment of an osteotomy guide in accordance with the present invention;  
         [0032]    [0032]FIG. 5B is an elevational view thereof taken along the longitudinal axis of the handle;  
         [0033]    [0033]FIG. 6 is an anterior elevational view illustrating the femoral head and neck severed along the cut line indicated by the osteotomy guide;  
         [0034]    [0034]FIG. 7 is an anterior elevational view illustrating the removal of a portion of the femoral head and neck;  
         [0035]    [0035]FIGS. 8A and 8B illustrate preparation of the acetabulum to receive the acetabular cup;  
         [0036]    [0036]FIG. 9 is a side elevational view of an acetabular cup inserter relative to a patient lying in the supine position;  
         [0037]    [0037]FIG. 10 is an anterior elevational view of a portion of the cup inserter illustrated in FIG. 9 and a patient lying in the supine position;  
         [0038]    [0038]FIG. 11 is a side elevational view illustrating the use of a curved awl to locate a posterior incision;  
         [0039]    [0039]FIG. 12 is a side elevational, partial sectional view of an awl in accordance with the present invention;  
         [0040]    [0040]FIG. 13 is a perspective view illustrating the insertion of a posterior retractor in the posterior incision;  
         [0041]    [0041]FIG. 14 is a perspective, exploded view of one embodiment of a tubular retractor in accordance with the present invention;  
         [0042]    [0042]FIG. 14A is a side elevational view of an alternative embodiment of the tubular retractor;  
         [0043]    [0043]FIG. 15 is a perspective view illustrating the insertion of a guide wire into the tubular retractor;  
         [0044]    [0044]FIG. 16 is a perspective view illustrating reaming of the femoral shaft;  
         [0045]    [0045]FIG. 17A is a perspective view of an end cutter;  
         [0046]    [0046]FIG. 17B is a perspective view of a femoral reamer;  
         [0047]    [0047]FIG. 18 is a side elevational, partial sectional view of an end cutter inserted into a tubular retractor of the present invention;  
         [0048]    [0048]FIG. 19 is a perspective view of a rasp handle after inserting a rasp into the femoral shaft;  
         [0049]    [0049]FIG. 19A is a perspective view illustrating an inserted rasp, with the rasp handle removed, and with the cable used to affix the rasp to the rasp handle protruding from the posterior incision;  
         [0050]    [0050]FIGS. 20A and 20B are partial sectional views of the rasp handle;  
         [0051]    [0051]FIG. 21 is an exploded view of the rasp handle and a rasp to be connected thereto;  
         [0052]    [0052]FIG. 21A is a partial elevational view along line  21 A- 21 A of FIG. 21;  
         [0053]    [0053]FIG. 22 is a perspective view illustrating placement of a provisional neck of the present invention;  
         [0054]    [0054]FIG. 23 is a perspective view of the provisional neck and mating forceps of the present invention;  
         [0055]    [0055]FIG. 24A is a partial sectional, radial elevational view of the provisional neck;  
         [0056]    [0056]FIGS. 24B and 24C are radial elevational views thereof;  
         [0057]    [0057]FIG. 25 is a perspective view illustrating the insertion of a femoral stem with a protective bag through the posterior incision;  
         [0058]    [0058]FIG. 26 is a perspective view illustrating alignment of the femoral stem while observing through the anterior incision;  
         [0059]    [0059]FIG. 27 illustrates an incision into the femoral stem protective bag prior to insertion of the femoral stem into the femoral shaft;  
         [0060]    [0060]FIG. 28 is a perspective view illustrating removal of the femoral stem protective bag while inserting the femoral stem, with observation through the anterior incision;  
         [0061]    [0061]FIG. 29 is a perspective view of a femoral stem insertion tool in accordance with the teachings of the present invention; and  
         [0062]    [0062]FIG. 30 is a perspective view of a hip prosthesis which can be implanted according to the method of the current invention. 
     
    
       [0063]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0064]    A total hip arthroplasty can be performed, according to the teachings of the current invention through two incisions, each no more than 5 centimeters (2 inches) in length. An anterior incision is made along the axis of the femoral neck, while a posterior incision is made generally in axial alignment with the femoral shaft. Referring to FIG. 1, a partial illustration of a patient  40  including torso  52 , buttock  50 , and leg  48  illustrates prior art incision  42  as well as anterior incision  44  and posterior incision  46  of the current invention. Prior art incision  42  is approximately 25 centimeters (10 inches) long, while anterior incision  44  and posterior incision  46  are each no more than 5 centimeters (2 inches) in length.  
         [0065]    According to the method of total hip arthroplasty of the current invention, patient  40  is initially placed in a supine position on an operating table. Either a standard operating table or, alternatively, a radiolucent Jackson table is used. A radiolucent Jackson table is preferred if the surgical team intends to use intraoperative image intensification. In one exemplary embodiment, a Storz viewsite endoscopic system can be used. A Storz viewsite endoscopic system provides a sterile viewing screen for endoscopic images. The sterile viewing screen of a Storz viewsite endoscopic system can be positioned within the surgical field immediately adjacent to anterior incision  44 . Other known endoscopic systems may further be utilized during the total hip arthroplasty of the present invention. Referring now to FIG. 2, with ipsilateral leg  48  in a neutral position, two prominent bony landmarks are palpated, the anterior superior iliac spine (ASIS)  59  and the greater trochanter  58  of femur  62 . Ilium  64  and pubis  66  of hip  68  are shown to better illustrate the relevant area of the body. In one exemplary embodiment, the approximate anterior incision starting point  71  is identified two fingerbreadths inferior and two fingerbreadths anterior to the tubercle of the greater trochanter  58 . The approximate finish point for the anterior incision is identified three fingerbreadths inferior and two fingerbreadths lateral to the anterior superior iliac spine (ASIS)  59 . In another exemplary embodiment, the approximate anterior incision starting point  71  is identified 3-4 centimeters inferior and 2 centimeters lateral to ASIS  59 . Having identified starting point  71  3-4 centimeters inferior and 2 centimeters lateral to ASIS  59 , the path of anterior incision  44  is extended obliquely from starting point  71  toward the prominence of greater trochanter  58  along the axis of femoral neck  60 . With the use of a spinal needle, the appropriate starting point  71  and the path of the anterior incision are identified by impaling the skin down to bone to confirm the central axis  70  of femoral neck  60 .  
         [0066]    An oblique incision of approximately 3.75-5 centimeters (1.5-2 inches) is made from the starting site  71  toward the prominence of the greater trochanter along the axis  70  of the femoral neck  60  and the central axis of acetabulum  54 . The incision is extended along the same plane through subcutaneous tissues, exposing the underlying fascia lata. The internervous plane between the tensor fascia lata muscle and the sartorius is identified by palpation and developed by curved scissors and blunt dissection. The sartorius can be made more prominent by externally rotating the leg to apply tension on the muscle. Deep to the tensor fascia lata and the sartorius is an internervous interval between the rectus femoris and the gluteus medius. This plane is developed by blunt dissection. A lateral retraction of the tensor fascia lata permits a visualization of the capsule  74  of the hip joint as illustrated in FIG. 2A.  
         [0067]    Leg  48  is externally rotated to create tension on capsule  74 . Capsule  74  is incised along the axis  70  (FIG. 2) of femoral neck  60  from the equator of femoral head  56  to the intertrochanteric ridge on the femur  62 . The capsular incision takes the form of an “H-shaped” window formed by incisions  72 . The H-shaped window is formed by adding supplementary perpendicular limbs around the equator of the femoral head  56  and the base of the femoral neck  60  to the initial incision along the axis  70  of femoral neck  60 . As a form of retraction, heavy sutures are used to provisionally attach the capsular flaps  73  to the subcutaneous tissues. As illustrated in FIG. 3, retractors  76  are placed inside capsular flaps  73  and underneath the superior and inferior borders of femoral neck  60  to expose the entire length of femoral neck  60  from the inferior aspect of femoral head  56  to the intertrochanteric ridge. Retractors  76  can be, e.g., Cobra retractors. In one exemplary embodiment, each retractor houses a light source and can also serve to anchor an endoscope. Retractors  76  thereby provide continuous visualization and illumination of the wound. In one exemplary embodiment, JAKOSCOPE retractors having integral fiberoptic light sources are utilized in accordance with present inventions.  
         [0068]    Referring now to FIG. 4, a femoral cutting tool  86 , e.g., an oscillating saw or a power burr is used to excise femoral neck  60 . A custom osteotomy guide  78  is placed through anterior incision  44  (FIG. 1) and functions to guide the femoral neck cut. Alignment portion  82  of osteotomy guide  78  is aligned with the longitudinal axis of femur  62 , while cut guide  84  is positioned on femoral neck  60 . Handle  80  of osteotomy guide  78  facilitates positioning and repositioning of osteotomy guide  78  through anterior incision  44 . After placement of osteotomy guide  78 , cut line  85  is scored as is known in the art. Osteotomy guide  78  is thereafter removed through anterior incision  44  and femoral cutting tool  86  is inserted through anterior incision  44  and utilized to cut along cut line  85  and displace portion  88  (FIG. 6) from femur  62 .  
         [0069]    Retractors  76  are repositioned around the anterior and posterior rims of the acetabulum. A custom curved cutting tool. (i.e., the “ligamentum teres cutter”) is passed behind femoral head  56  to sharply incise the ligamentum teres, thus mobilizing cut portion  88  as illustrated in FIG. 6. Cut portion  88  includes femoral head  56  as well as a portion of femoral neck  60  (FIG. 4). Cut portion  88  is thereafter removed through anterior incision  44  with a custom femoral head bone grasper  94  (FIG. 7). If there is difficulty removing cut portion  88  in one piece, it may be in situ morselized using cutting tool  87  (FIG. 6), e.g., a power burr. Morsels  92  may then be removed through anterior incision  44 . Morselizing of cut portion  88  is accomplished making cuts which substantially mirror the cuts in hip capsule  74 . In one exemplary embodiment, a corkscrew and hip skid removes the entire femoral neck, as in hip fracture. Irrigation and suction devices can be used to cool the bone and facilitate the removal of bony debris in hip capsule  74 . In one exemplary embodiment, a fiberoptic endoscope is placed into the hip joint to confirm the complete removal of bony debris.  
         [0070]    As illustrated in FIG. 8A, the fibro-fatty tissue within the cotyloid fossa of acetabulum  54  is removed with the use of, e.g., a high-speed acorn-tipped cutting tool  96 , Rongeur forceps, and a curette. Thereafter, the acetabular labrum is trimmed with a scalpel. As illustrated in FIG. 8B, acetabulum  54  is then progressively reamed with standard acetabular reamer  98 . Acetabular reamers within a predetermined size range are utilized until the optimal size of the acetabulum is reached. Sizing of the acetabulum is facilitated by the use of pre-operative templates and radiographs as is known in the art. Once again, an endoscope can be used to aid in visualization during the reaming process. Typically the acetabulum is under reamed by approximately 2 mm with respect to the diameter of the anticipated acetabular cup so as to create an interference fit. High speed acorn-shaped cutting tool  96 , and acetabular reamer  98  enter the body through anterior incision  44 .  
         [0071]    After a trial fitting, a press-fit acetabular cup of the appropriate size is firmly seated with a standard cup inserter  100  as illustrated in FIG. 9 and impacted into the acetabular recess as is known in the art. Acceptable press fit acetabular cups include the ZIMMER HGP II or TRILOGY cups. Proper positioning of the acetabular cup is achieved with a custom anteflexion and pelvic alignment guide. Patient  40  is placed in supine position on operating table  102 . Aligning rod  104  is aligned with the mid lateral axis of torso  52  while main shaft  105  is maintained approximately 30° from operating table  102  for proper seating of the acetabular cup. To augment fixation of the cup, a flexible drill can be used to guide the placement of one or more acetabular screws. In some cases, acetabular screws will not be necessary. The insertion of the acetabular liner is deferred until the proximal femur has been prepared for the insertion of a trial stem. As illustrated by the anterior elevational view of FIG. 10, patient  40  remains in the supine position on operating table  102  (FIG. 9) while cup inserter  100  is utilized to seat the acetabular cup.  
         [0072]    For preparation of the femur, the patient is repositioned with a pad placed under the ipsilateral hip. The hip is slightly flexed, adducted approximately 30°, and maximally externally rotated. Retractors  76  are repositioned around the medial and lateral aspects of femur  62 . Alternatively, a self-retaining retractor with a light source attachment and an endoscope holder can be positioned in anterior incision  44  to provide constant visualization and illumination of femur  62 .  
         [0073]    With a scalpel or curved osteotome, the soft tissues along the anterior surface of femur  62  just inferior to the intertrochanteric ridge are subperiosteally reflected to expose the bone for a width of approximately 1 cm. This sharp subperiosteal elevation continues superolaterally onto the anterior margin of the greater trochanter. Then with curved Mayo scissors a pathway is developed by blunt dissection that is directed superficially to the anterior fibers of the gluteus minimus towards buttock  50  (FIG. 11).  
         [0074]    As illustrated in FIG. 11, awl  106  is inserted through the anterior incision  44 , directed through the cleft between the gluteus medius and maximus in line with the shaft of the femur and piriformis fossae region, and advanced into the soft tissues of buttock  50  until its pointed distal end  108  can be palpated on the surface of the skin. Distal end  108  of awl  106  is generally aligned with the longitudinal axis of femur  62 . At the point where distal end  108  is palpated, posterior incision  46  of approximately 2-3 cm (0.8-1.2 inches) is made and extended through the subcutaneous tissues and fascia lata to expose the underlying gluteus maximus. A tract to femur  62  is developed along the path created by awl  106 . The gluteus maximus is split bluntly in line with its fibers with curved Mayo scissors. Finger dissection may be utilized to reach the posterior piriformis fossa region. Into this pathway, via posterior incision  46 , custom elliptical posterior retractor  122 , complete with its inner sleeves, is threaded (FIG. 13) down to the osteotomized femoral neck. In one exemplary embodiment, elliptical posterior retractor  122  includes posterior lip  128  (FIG. 14). In this embodiment, retractor  122  is threaded down to the osteotomized femoral neck until posterior lip  128  lies beneath the posterior intertrochanteric ridge. FIG. 14A illustrates an embodiment of rasp tunnel  130  without posterior lip  128 . In an alternative embodiment, each component of posterior retractor  122  (i.e., guide tube  124 , reamer tunnel  126 , and rasp tunnel  130 ) is individually inserted and removed as necessary. In an embodiment in which guide tube  124 , reamer tunnel  126 , and rasp tunnel  130  are individually inserted and removed into posterior incision  46 , each individual tunnel may be provided with a posterior lip similar to posterior lip  128  illustrated in FIG. 14. Rasping and reaming of the femur will now be described. The posterior capsule will be entered to facilitate rasping and reaming of the femur.  
         [0075]    Referring now to FIG. 15, blunt tipped guide wire  146  is inserted through guide tube  124  of posterior retractor  122  and advanced into femoral canal  148 . While FIG. 15 illustrates guide tube  124  nested in reamer tunnel  126  and rasp tunnel  130 , guide tube  124  may be directly inserted through posterior incision  46 . If the cancellous bone of femur  62  is too dense to permit insertion of blunt tipped guide wire  146 , then a conical cannulated reamer or end mill is used to prepare the femoral metaphysis. If a nested posterior retractor configuration is utilized, guide tube  124  must be removed so that the reamer can be inserted through reamer tunnel  126  of posterior retractor  122 . Similarly, if a nested configuration is not utilized, reamer tunnel  126  must be inserted into posterior incision  46 . In any event, blunt tipped guide wire  146  is inserted about halfway down femoral canal  148 . The following detailed description of the invention makes reference to a nested posterior retractor configuration. It will be understood by those skilled in the art that if the nested configuration is not utilized, each individual component of posterior retractor  122  will be inserted and removed through posterior incision  46  as necessary.  
         [0076]    [0076]FIG. 16 illustrates preparation of femoral canal  148  to receive rasp  204  (FIG. 19). Guide tube  124  is removed from posterior retractor  122  and end cutter  150  (FIG. 17A) is inserted through reamer tunnel  126 . FIG. 18 illustrates end cutter  150  positioned within reamer tunnel  126 . End cutter  150  includes elongate aperture  160  through which guide wire  146  passes and guides end cutter  150 . End cutter  150  is actuated by any of the many actuating devices known in the art. After end cutting is complete, end cutter  150  is removed through reamer tunnel  126  and reamer  151  (FIG. 17B) is inserted therethrough. Reamer  151  includes reamer guide aperture  161  through which guide wire  146  passes and guides reamer  151  as it reams femoral canal  148 . Reamers of progressive increase in their outer diameter are sequentially placed over guide wire  146  and femoral canal  148  is reamed until cortical “chatter” is felt. As is known in the art, the optimal diameter of femoral canal  148  is provisionally determined by preoperative templating. Some surgeons may choose to avoid reaming of the femoral shaft and instead utilize a broach as is known in the art. A broach may be inserted in accordance with the current invention as described hereinbelow with respect to rasp insertion.  
         [0077]    After the correct diameter of femoral canal  148  is reamed out, reamer tunnel  126  (FIG. 14) is removed from posterior retractor  122  so that rasp  204  and rasp handle  212  (FIG. 19) can be inserted over guide wire  146  to complete preparation of femur  62 . Guide wire  146  is inserted into rasp guide aperture  214  and rasp handle guide aperture  202  to guide rasp  204  to prepared femur  62 . Impact surface  164  is struck, as is known in the art, to place rasp  204  in femur  62 . While rasp  204  is being impacted, the rotational alignment can be assessed by direct visual scrutiny of femur  62  through anterior incision  44 . Furthermore, assessment of the alignment of rasp handle  212  with respect to the patella, lower leg, and foot facilitates alignment. On the normal proximal femoral metaphysis, a flattened area of anterior bone provides a highly reproducable landmark for the rotational alignment. This may not be true if the patient has experienced prior surgery or trama.  
         [0078]    Progressively larger rasps are inserted to achieve the optimal fit and fill in femur  62 . Once the final rasp is fully seated, rasp handle  212  is removed along with guide wire  146  and posterior retractor  122 , leaving distal end  208  of flexible cable  192  (FIG. 19A) attached to the proximal end of rasp  204  and proximal end  194  of flexible cable  192  protruding from posterior incision  46 . The operation of rasp handle  212  will be further explained below.  
         [0079]    After the final rasp is seated in femoral canal  148 , a trial acetabular liner is placed through anterior incision  44  and into the seated acetabular cup with the use of a liner inserter as is known in the art. Provisional neck  222  is inserted through anterior incision  44  and locked to the top end of the seated rasp, as illustrated in FIG. 22. A trial femoral head is placed on the Morse taper of provisional neck  222  through anterior incision  44 . The hip joint is reduced for an assessment of stability of the hip joint and limb length. Where necessary, a second assessment is made. Once the trial reduction is satisfactorily completed, the hip is dislocated and the provisional head and provisional neck  222  are removed. Rasp handle  212  is reinserted through posterior incision  46  over the free end of flexible cable  192 . Rasp handle  212  is advanced until it can be locked with the seated rasp so that impact surface  164  can be impacted and the entire tool (i.e., rasp  204  and rasp handle  212 ) can be removed. The trial acetabular liner is removed through anterior incision  44 . In an alternative embodiment, a trial reduction can be performed utilizing the final femoral implant and a trial femoral head.  
         [0080]    Via anterior incision  44 , the final acetabular liner  252  (FIG. 30) is seated into acetabular cup  250  (FIG. 30) with a liner inserter that permits its impaction in place, as is known in the art. Femoral implant  238  (FIG. 30) is anchored to femoral stem insertion tool  240  (FIG. 29) and placed through posterior incision  46 . Femoral implant  238  can be, e.g., a VERSYS fiber metal taper, or a VERSYS fiber metal midcoat available from Zimmer, Inc. As illustrated in FIG. 25, femoral implant  238  is placed in protective, disposable bag  242  prior to its introduction into posterior incision  46 . Protective, disposable bag  242  keeps femoral implant  238  clean as it is inserted through posterior incision  46 . Note that FIG. 25 illustrates femoral implant  238  oriented as it will be when placed in femur  62 . To insert femoral implant  238  through posterior incision  46 , femoral implant  238  must be rotated 180° from this position to prevent impingement on the body. Femoral implant  238  is then rotated 180° after being completely inserted through posterior incision  46 .  
         [0081]    [0081]FIG. 26 illustrates femoral stem  238  and bag  242  inserted through posterior incision  46 . When the tip of femoral stem  238  approaches the osteotomized femoral neck, the distal end of bag  242  is incised as illustrated in FIG. 27. Scalpel  246  is inserted into anterior incision  44  to incise bag  242 . As femoral stem  238  is driven into femoral canal  148 , bag  242  is progressively removed through posterior incision  46  as illustrated in FIG. 28. After femoral stem  238  is fully seated, femoral stem insertion tool  240  (FIG. 29) is removed through posterior incision  46 . Through anterior incision  44 , the final femoral head is positioned on the femoral neck Morse taper using a standard holding device and secured with a standard impaction tool and mallet. The hip is then reduced and assessed for stability.  
         [0082]    After appropriate antibiotic irrigation and pulsatile lavage, the hip capsule and the soft tissues are repaired with heavy sutures or staples. A suitable local anesthetic solution is injected into the closed hip joint as well as the capsular layer and the subcutaneous tissues, allowing superior postoperative pain relief. The fascial layers, subcutaneous tissues, and skin of both anterior and posterior wounds are closed in a conventional method and dressings are applied. A suction drain may be used at the discretion of the surgeon.  
         [0083]    Osteotomy guide  78 , illustrated in use in FIG. 4, includes handle  80 , alignment portion  82 , and cut guide  84 . In one exemplary embodiment, cut guide  84  and alignment portion  82  form a 60° angle. In one exemplary embodiment, alignment portion  82  includes a tapered distal end as illustrated in FIGS. 5A and 5B. Osteotomy guide  78  is inserted through anterior incision  44  and is positioned with alignment portion  82  being placed on femur  62  so that alignment portion  82  generally aligns with the longitudinal axis of femur  62 . Handle  80  protrudes through anterior incision  44  and may be utilized to position osteotomy guide  78 . After osteotomy guide  78  is properly positioned, cut guide  84  is utilized to mark cut line  85  on femoral neck  60  as illustrated in FIG. 4. Osteotomy guide  78  can be formed to function on either side of the body. FIG. 4 illustrates an osteotomy guide designed to function on the right femur, while FIG. 5B illustrates an osteotomy guide operable to function on the left femur.  
         [0084]    As discussed supra, awl  106  (FIG. 12) is designed for insertion through anterior incision  44  to locate posterior incision  46  (FIG. 11). Awl shaft  116  includes proximal end  110  designed for insertion into handle  112 . Handle  112  includes a longitudinal channel  120  into which proximal end  110  of awl shaft  116  may be inserted. Locking screw  118  is operably positioned in handle  112  and may be actuated by locking knob  114 . Locking knob  114  is utilized to place locking screw  118  in locking engagement with proximal end  110  of awl  106 . In one exemplary embodiment, proximal end  110  of awl  106  includes a flat portion to engage locking screw  118  and facilitate the locking engagement of awl shaft  116  to handle  112 . Awl shaft  116  further includes distal end  108 . Distal end  108  is generally straight and is utilized to generally align with a longitudinal axis of femur  62  (FIG. 1). As illustrated in FIG. 12, distal end  108  of awl shaft  116  includes a tapered end to facilitate insertion of awl  106  through anterior incision  44  to locate posterior incision  46 . Additionally, distal end  108  of awl  106  may be of smaller diameter than the body of awl shaft  116  as illustrated in FIG. 12. In an alternative embodiment, awl  106  is formed in one piece and is disposable.  
         [0085]    Referring now to FIG. 14, posterior retractor  122  comprises three nested parts. Guide tube  124  is nested in reamer tunnel  126  while reamer tunnel  126  is nested in rasp tunnel  130 . When posterior retractor  122  is threaded into posterior incision  46 , guide tube  124 , reamer tunnel  126 , and rasp tunnel  130  can be nested together to form a single unit. Rasp tunnel  130  includes exterior threads  132  to facilitate threading of posterior retractor  122  through posterior incision  46 . Rasp tunnel  130  includes rasp aperture  134  through which reamer tunnel  126  may be inserted and, in one alternative embodiment, posterior lip  128  for positioning posterior retractor  122 , as discussed above. Reamer tunnel  126  includes flange  136  which is operable to retain the position of reamer tunnel  126  within rasp tunnel  130 . Reamer tunnel  126  includes reamer aperture  138  through which guide tube  124  may be inserted. Guide tube  124  includes a tapered distal end  140  to facilitate its insertion into reamer aperture  138 . Guide tube  124  includes guide wire aperture  144  through which guide wire  146  (FIG. 15) may be inserted. Reamer aperture  138  is sized to allow insertion of end cutter  150  (FIG. 18), or femoral reamer  151  as discussed above. As illustrated in FIG. 18, guide tube  124  is removed from reamer tunnel  126  and end cutter  150  is inserted through reamer aperture  138 . Longitudinal reamer aperture  138  is sized to accommodate guide cylinders  156  and to thereby provide guidance and stability to end cutter  150 . After end cutting (and reaming, if desired) is complete, reamer tunnel  126  is removed from rasp tunnel  130 . Rasp aperture  134  is sized to accommodate insertion of rasp  204  as well as cannular insertion member  168  of rasp handle  212 . For surgeries which do not utilize reaming, the posterior retractor can comprise a rasp tunnel with a guide tube nested therein and not include a reamer tunnel as described above. As described above, posterior retractor  122  is not always utilized in its nested configuration. In one exemplary embodiment, guide tube  124 , reamer tunnel  126 , and rasp tunnel  130  are each inserted into and removed from posterior incision  46  as necessary.  
         [0086]    Referring now to FIG. 21, rasp handle  212  includes cannular insertion member  168 , impact surface  164 , grip  166 , elongate guide aperture  202 , elongate aperture  200 , and engagement channel  190 . Rasp  204  includes an aperture  216  sized to receive and retain retainer  210  on distal end  208  of flexible cable  192 . Retainer  210  is placed in aperture  216  and flexible cable  192  follows cable channel  217  to exit rasp  204 . Proximal end  194  of flexible cable  192  is inserted through elongate aperture  200  of cannular insertion member  168  and distal rasp engagement guide  206  is piloted to guide channel  215  of rasp  204 . After exiting the proximal end of elongate aperture  200 , proximal end  194  of flexible cable  192  may be received in engagement channel  190 . Engagement channel  190  is sized to accommodate and retain retainer  196 . After retainer  196  is operably positioned in engagement channel  190 , grip  166  may be actuated to tension flexible cable  192 .  
         [0087]    Referring now to FIG. 20B, retainer  196  is operably positioned in engagement channel  190 . Attaching means  184 , such as, e.g., rivets, belts, etc. are utilized to affix biasing elements  172  to grip  166  and internal handle surface  182 . Grip  166  is outwardly biased by handle biasing elements  172  and pivots about pivot point  198 . Grip  166  includes tensioning member  188  and ratchet  174 . Ratchet  174  is designed for engagement with tapered end  186  of pawl  176 . Pawl  176  includes pawl flange  178 . Spring  180  engages internal handle surface  82  and pawl flange  178  to bias pawl  176  toward cannular insertion member  168 . Actuation of grip  166  against the biasing force of biasing elements  172  rotates grip  166  about pivot point  198 , causes ratchet  174  to come into operative engagement with tapered end  186  of pawl  176 , and causes tensioning member  188  to contact flexible cable  192 . FIG. 20A illustrates grip  166  retained by pawl  176  in the closed position. As illustrated, tensioning member  188  contacts and tensions flexible cable  192 , thus locking rasp  204  to rasp handle  212 . Lock disengagement knob  170  can be pulled against the biasing force of spring  180  to unlock grip  166 .  
         [0088]    Referring now to FIG. 23, provisional neck  222  can be locked to rasp  204  utilizing forceps  220 . Forceps  220  include blade ends  230 ,  232 . Blade ends  230 ,  232  are sized for insertion into provisional head apertures  234 ,  236 , respectively (FIGS. 24B and 24C). As illustrated in FIG. 24A, provisional neck  222  includes locking cylinder  224  and spring  228 . Spring  228  upwardly biases locking cylinder  224 . Upon insertion into apertures  234 ,  236 , blade ends  230 ,  232  can contact tapered portion  226  of locking cylinder  224 . Actuation of blade ends  230 ,  232  against tapered portion  226  causes locking piston  224  to move in a direction opposite to the biasing force of spring  228 . Provisional neck  222  is clamped to forceps  220  and slid in a radial direction into provisional neck engagement area  218  (FIGS. 21 and 21A) on rasp  204 . After provisional neck  222  is fully slid onto rasp  204 , forceps  220  may be released, thereby allowing locking piston  224  to return to its locked position under the biasing force of spring  228 . Rasp  204  includes circular cut outs  217  which can be engaged by locking cylinder  224  to lock provisional neck  222  in place.  
         [0089]    Channels  225  (FIG. 24A) on provisional neck  222  accommodate protrusions  219  (FIG. 21) on rasp  204 . Provisional neck  222  is slid onto rasp  204  with protrusions  219  occupying channels  225  of provisional neck  222 . Stop  223  of provisional neck  222  abuts protrusions  219  when provisional neck  222  is completely slid onto rasp  204 . When stop  223  abuts protrusions  219 , locking cylinder  224  may be locked (i.e., forcep blades  230 ,  232  released) so that locking cylinder  224  engages circular cut outs  217 , locking provisional neck  222  to rasp  204 .  
         [0090]    While the method of the current invention has been described with reference to a particular hip prosthesis, this is not meant to be limiting in any way and it will be understood that the method of the current invention could be used with many prosthetics, including, e.g., a cementless prosthesis, a hybrid prosthesis having a cemented stem and a cementless acetabular cup, a cemented prosthesis having both a cemented stem and a cemented acetabular cup, or an Endo prosthesis for replacing only the femoral head. In a procedure in which a cemented femoral stem is utilized, the bone cement will generally be inserted through the anterior incision. It should also be understood by those skilled in the art that in a smaller patient the method of the current invention could be performed entirely through the anterior incision with no need to make a posterior incision as described above.  
         [0091]    While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Technology Category: 1