Abstract:
The invention discloses a surgical technique and apparatus for minimally invasive replacement of a fractured femoral head in hip arthroscopy. The fractured femoral head is first removed from the patient, and an incision made on the patient on a lateral aspect of the operative thigh. A hole is then drilled into the cortex of the operative femur of the patient through the incision. The femoral neck and femoral canal of the operative femur are reamed by inserting a reamer through the drilled hole. A hip prosthesis is then inserted into the wound and injected with molding. The hip prosthesis includes a femoral component having a distal end and a proximal end, the distal end inserted and anchored in the reamed femoral canal, and a femoral head component with smooth surface. The femoral head component contains a deflated balloon that, when inflated with molding, is similar to a neo-femoral head.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of and claims priority to U.S. Nonprovisional application Ser. No. 13/349,264, entitled “Injectable Hip Hemiarthroplasty”, filed Jan. 12, 2012 by the same inventor, which claims priority to U.S. Provisional Application No. 61/431,933, entitled “Injectable Hip Hemiarthroplasty”, filed on Jan. 12, 2011 by the same inventor, both of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates, generally, to hip surgery. More particularly, it relates to a surgical technique for hemiarthroplasty that is minimally invasive and has reduced post-operative pain. 
     2. Description of the Prior Art 
     Approximately 300,000 patients experience a fracture of the hip due to osteoporosis every year. These patients are generally elderly and often have multiple pre-existing medical conditions, making them poor candidates for a surgical procedure. 
     Current treatments for hip fracture include total hip arthroplasty (replacement of the femoral and acetabular sides of the hip joint), hip hemiarthroplasty (replacement of the fractured femoral side of the hip only, leaving the native acetabulum in place), and hip pinning with cannulated screws. Occasionally a hip fracture will warrant a hip disarticulation. 
     The type of treatment for hip fracture is decided by factors such as the patient&#39;s pre-fracture level of activity, the existence of pre-existing arthritis, and the patient&#39;s health and ability to tolerate surgery. Younger patients who are active are often candidates for hip pinning, so that their native femur may be saved. For patients who are ambulatory and have arthritis, total hip arthroplasty is typically performed. For patients who are ambulatory and do not have arthritis, hip hemiarthroplasty is typically performed. Though less common, hip pinning may be chosen for elderly patients who are not ambulatory if they are judged to be poor surgical candidates and require a less invasive procedure. 
     International Patent Application No. PCT/US99/08906 discloses a surgical technique of removing the fractured femoral head from a body and inserting a neo-femoral head joined to the native femoral neck. The neo-femoral head comprises a bio-absorbable expandable balloon that is filled with a molding material within the body and forms the shape of the neo-femoral head. 
     However, several issues arise in this conventional technology. First, the device is made of a bio-absorbable material that will disintegrate over time. The intent of the procedure is for the patient to undergo 6-8 weeks of post-operative crutch-walking, during which time bone will replace the inserted material. Based on known rates of creeping substitution, the process by which bone incorporates bone-line materials may take 10-20 years, prior to which the device would likely fail. Moreover, the neo-femoral head is supported only by a thin cylindrical stem through the femoral neck, thus being susceptible to cantilever bending forces. 
     Accordingly, what is needed is a rigid, minimally invasive, immediately weight-bearing surgical procedure and apparatus for performing hip hemiarthroplasty. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill how the art could be advanced. 
     While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention. Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein. 
     The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein. 
     In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned. 
     SUMMARY OF THE INVENTION 
     The long-standing but heretofore unfulfilled need for a minimally invasive, immediately weight-bearing method and apparatus for replacing the fractured femoral side of the hip is now met by a new, useful and nonobvious invention. 
     The disclosed invention is a novel surgical technique for minimally invasive replacement of a hip hemiarthroplasty which requires the use of commercially available instruments for hip arthroscopy and a new type of balloon hip hemiarthroplasty component that requires injection of bone cement. 
     People who may need this novel surgical technique include patients with hip fractures who are limited in their walking capacity or are not candidates for a more invasive procedure, such as hip hemiarthroplasty with a metallic prosthesis. The increasing number of elderly patients would benefit from a less invasive procedure that brings pain relief similar to a hip hemiarthroplasty. 
     The invention discloses a surgical technique for minimally invasive replacement of a femoral head in hip arthroscopy. The steps comprise placing a patient with fractured hip, containing a fractured femoral head and a femoral neck, in a supine position suitable for the surgical technique. The fractured femoral head is then removed from the patient, and an incision is made on the patient on a lateral aspect of the operative thigh. A hole is then drilled into the cortex of the operative femur of the patient through the incision. The femoral canal of the operative femur can be reamed by inserting a reamer through the drilled hole. The reamer has a flexible shaft and is disposed within a lumen of a trajectory guidance tube. The surgical technique continues by inserting a hip prosthesis into the wound. The hip prosthesis contains a femoral component attached to a deflated balloon with smooth surface. The hip prosthesis can then be injected with a molding, such that the deflated balloon becomes inflated and similar to a neo-femoral head. 
     In an embodiment, when the patient is placed in the supine position, the operative leg of the patient can be internally rotated by about 15°, so the surgeon can orient surgical instruments parallel to a landmark to achieve correct orientation to the femoral neck. 
     In an embodiment, the step of removing the fractured femoral head from the patient can be performed using a camera, a grasper, or a bone burr. 
     In an embodiment, the drilled hole is about 15 mm in diameter to about 20 mm in diameter. 
     In an embodiment, the trajectory guidance tube contains a 90° elbow to direct the reamer down the length of the femoral canal. 
     In an embodiment, the molding is bone cement. 
     In an embodiment, the deflated balloon can be inflated with water or air prior to inflating the deflated balloon with the molding. 
     In an embodiment, the hip prosthesis includes an external sleeve containing a flexible rod to guide the hip prosthesis into correct position within the subject. The external sleeve is disposed adjacent to the femoral component. In a further embodiment, the external sleeve is collapsible. 
     In an embodiment, the hip prosthesis includes a insertion sleeve surrounding the deflated balloon. In a further embodiment, the hip prosthesis further includes a guiding string attached to the insertion sleeve. A force can be applied to the guiding string to guide the hip prosthesis into the correct position within the patient. In a further embodiment, the insertion sleeve includes a tab that is pulled to detach the insertion sleeve from the hip prosthesis, so the insertion sleeve can be removed from the patient. 
     In an embodiment, insertion of the hip prosthesis into the patient can be facilitated by rolling the hip prosthesis into a slimmer form prior to insertion into the patient. 
     In an embodiment, each component of the surgical technique can be monitored with fluoroscopy while the surgical technique is being performed. 
     In a separate embodiment, the invention discloses a surgical technique for minimally invasive replacement of a femoral head in hip arthroscopy. The steps comprise placing a patient with fractured hip, containing a fractured femoral head and a femoral neck, in a supine position. The patient is positioned with operative leg internally rotated by about 15°, so a surgeon can orient surgical instruments parallel to a landmark to achieve correct orientation to the femoral neck. The surgeon then removed the fractured femoral head from the patient by using a camera, a grasper, or a bone burr. The surgeon then makes an incision on a lateral aspect of an operative thigh of the subject, so the incision is coincident to a line drawing through a path of the femoral neck. The surgeon then drills a hole into the cortex of the operative femur of the patient through the incision. The hole is about 15 mm in diameter to about 20 mm in diameter. The surgeon then reams the femoral canal of the operative femur by inserting a reamer through the drilled hole. The reamer has a flexible shaft and is disposed within a lumen of a trajectory guidance tube containing a 90° elbow. The region of the fractured hip is then irrigated with a pulse-lavage device. A hip prosthesis is rolled into a slimmer form to facilitate insertion into the patient. The hip prosthesis contains a deflated balloon with smooth surface, a insertion sleeve surrounding the deflated balloon, a femoral component inserted into a femoral canal, a collapsible external sleeve containing a flexible rod to guide the hip prosthesis into correct position within the patient, wherein the external sleeve is adjacent to the femoral component, a guiding string attached to the insertion sleeve, and a tab that is pulled to detach the insertion sleeve from the hip prosthesis, so the insertion sleeve can be removed from the patient. The hip prosthesis can then be inserted into the wound through the incision by inserting the distal end of the femoral component first, followed by the remainder of the hip prosthesis. The deflated balloon is then inflated with water or air and finally then inflated with bone cement, so the deflated balloon becomes inflated and similar to a neo-femoral head. 
     In a separate embodiment, the invention discloses a hip hemiarthroplasty device, comprising a femoral component having a distal end and a proximal end, the distal end inserted and anchored in the operative reamed femoral canal in the patient, and a femoral head component with smooth surface attached to the proximal end of the femoral component. The femoral head component contains a deflated balloon. The hip hemiarthroplasty device has a first position and a second position. The first position occurs when the hip hemiarthroplasty device is rolled lengthwise into a slimmer form. The second position occurs when the deflated balloon has been inflated with a molding within the patient. 
     In an embodiment, the device includes an external sleeve containing a flexible rod to guide the hip hemiarthroplasty device into correct position within the patient. The external sleeve is adjacent to the femoral component 
     In an embodiment, the device includes a insertion sleeve surrounding the deflated balloon. The device further includes a guiding string attached to the insertion sleeve. A force can be applied to the guiding string to guide the hip hemiarthroplasty device into the correct position within the patient. The device further includes a tab that can be pulled to detach the insertion sleeve from the device, so the insertion sleeve can be removed from the patient. 
     In an embodiment, the device further comprises a trajectory guidance tube adjacent to the device to guide the femoral component down the reamed femoral canal. 
     In an embodiment, the femoral component and the femoral head component include radioopaque markers to indicate positioning within the patient. 
     These and other important Objects, advantages, and features of the invention will become clear as this disclosure proceeds. 
     The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the disclosure set forth hereinafter and the scope of the invention will be indicated in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed disclosure, taken in connection with the accompanying drawings, in which: 
         FIG. 1  depicts an illustration of a subject in a supine position with common portals (i.e., anterior, anterolateral, lateral) for hip arthroscopy; 
         FIG. 2  depicts common portals (i.e., anterior, anterolateral, lateral) for hip arthroscopy; 
         FIG. 3  depicts a hip fracture with removed femoral head and a lateral thigh incision; 
         FIG. 4  depicts a lateral thigh incision and a lateral trochanteric osteomy hole within the cortex of a femoral neck; 
         FIG. 5  depicts a lateral thigh incision, a lateral trochanteric osteomy, and a reamed femoral neck; 
         FIG. 6  depicts a flexible reamer inside of a trajectory guidance tube with 90° elbow to direct the reamer down the femoral shaft; 
         FIG. 7  depicts depicts a lateral thigh incision, a lateral trochanteric osteomy, a reamed femoral neck and a reamed femoral canal; 
         FIG. 8  depicts a femoral component after inflation with bone cement, the femoral component superficially resembling a typical hemiarthroplasty component; 
         FIG. 9  depicts a femoral component and femoral head component rolled lengthwise to facilitate insertion into a subject, the femoral component having an inlet for cement injection; 
         FIG. 10  depicts a femoral component and femoral head component rolled lengthwise to facilitate insertion into a subject, the femoral component having a collapsible external sleeve along the femoral shaft portion of the component to allow positioning within the intramedullary canal; 
         FIG. 11  depicts a femoral component and femoral head component rolled lengthwise to facilitate insertion into a subject, the femoral component having a collapsible external sleeve along the femoral shaft portion of the component and a flexible insertion rod placed in the external sleeve; 
         FIG. 12  depicts a femoral component having an insertion sleeve with narrow base and attached guiding string to allow positioning in the acetabulum of a subject; 
         FIG. 13  depicts an illustration of a femoral component inserted into a femoral canal of a subject, the femoral component having a flexible rod inserted into an external sleeve, a trajectory guidance tube with 90° elbow, and guiding string for positioning of femoral head component in the acetabulum of the subject; 
         FIG. 14  depicts a femoral head component located in the acetabulum of a subject after a guiding string has been pulled through an arthroscopic portal; and 
         FIG. 15  depicts a resultant femoral head component upon inflation with molding within a subject and relative to the acetabulum of the subject. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part thereof, and within which are shown by way of illustration specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention. 
     Certain embodiments of the current invention can be used in lieu of hip hemiarthroplasty and/or hip pinning in a sedentary or household-ambulating patient who has a hip fracture. The advantages of the device are immediate fixation of the fracture, immediate weight bearing after surgery, and reduced invasiveness compared to a hip hemiarthroplasty. Hip hemiarthroplasty is performed more commonly for hip fractures than hip pinning because pinning requires a stable fracture pattern. 
     Preparing the Patient 
     A patient is positioned supine on an operating table. The operative leg can be internally rotated by about 15° to compensate for normal hip anteversion, such that the surgeon can orient instruments parallel to the operating room floor, ceiling, operating table, or other landmark to achieve correct orientation to the femoral neck. Using fluoroscopy, the hip landmarks can be established on the patient&#39;s skin. As depicted in  FIGS. 1 and 2 , common hip arthroscopic portals include anterior portal  2   a , anterolateral portal  2   b , and lateral portal  2   c . Once the desired portal  2   a ,  2   b ,  2   c  has been established within the patient, the hip capsule can be irrigated to remove hematoma from the capsule. 
     Fractured femoral head  4  is then removed. Femoral head  4  can be removed using common arthroscopic instruments, for example camera, grasper, and bone burr, to remove the femoral head fragments. Additional portals may be required to effectively immobilize femoral head  4  so that the burr may be used effectively. 
     Accessing the Operative Femur 
     Once femoral head  4  is removed and the fractured surface of the femoral neck has been irrigated and smoothed, incision  10  on the lateral aspect of the thigh is made as shown in  FIG. 3 . Incision  10  is positioned so that it is coincident to a line drawn through the path of the femoral neck. Dissection of the soft tissues is taken down to the lateral aspect of the greater trochanter. 
     As shown in  FIG. 4 , lateral trochanteric osteomy hole  12  is created in the cortex of the lateral femur by conventional instruments, for example a drill bit through incision  10 . The size of hole  12  varies with the size of the patient; however, hole  12  would typically range from about 15 mm to about 20 mm in diameter. 
     Reaming the Femoral Canal 
     As shown in  FIG. 5 , canal-finding reamer (not shown) of similar diameter to hole  12  is then used to extend hole  12  into the cortex through the femoral neck to create reamed femoral neck  14 . Canal-finding reamers are commercially available from many orthopedic companies. 
     As shown in  FIG. 6 , reaming of the femoral canal is undertaken using highly flexible-shaft reamers  16  and guide tube  18  with 90° elbow  20 . Guide tube  18  is used to direct flexible-shaft reamers  16  down femoral canal  22 . Flexible-shaft reamers are commercially available from many orthopedic companies. Reamers  16  may be marked to allow reaming to the proper depth. Reaming depth and trajectory can be checked with fluoroscopy, as depicted in  FIG. 7 . The use of reamer  16  in this manner may be enhanced in patients with low bone density (e.g., osteopenia or osteoporosis) with the use of flexible tube  34  that would traverse guide tube  18  with 90° elbow  20 . Flexible tube  34  can have an outer diameter slightly smaller than the inner diameter of guide tube  18 . Flexible tube  34  can have an inner diameter slightly larger than the outer diameter of reamer  116 . Flexible tube  34  would be advanced behind reamer  16  to prevent deviation of the course of reamer  16  outside of the bone. Flexible tube  34  could be made of any biocompatible, flexible synthetic materials, individually or in combination. 
     When reamer  16  has completed reaming femoral canal  22 , as depicted in  FIG. 7 , the entire wound can be irrigated with a commercially available pulse-lavage device (e.g., STRYKER ORTHOPAEDICS). 
     Inserting the Hip Prosthesis 
     Next, a hip prosthesis, denoted generally by the reference numeral  30 , is introduced into the wound. Hip prosthesis  30  includes femoral component  26  and femoral head component  28 . Femoral head component  28  includes deflated balloon  28   a , which, when inflated with a molding, for example bone cement (polymethylmethacrylate), would take the form of hip hemiarthroplasty component  28   b , as shown in  FIG. 8 . 
     Hip prosthesis  30  could take the form of several embodiments, all of which would be made with a liner that includes a flexible material that resists stretching. Many materials have this property; examples include fiberglass and carbon fiber. Femoral head component  28  is surfaced with a smooth material to allow low-friction articulation with acetabulum  8 . 
     Hip prosthesis  30  can be manufactured with radioopaque markers to indicate the most proximal and distal aspects of hip prosthesis  30  so that position of femoral component  26  and deflated femoral head component  28   a  may be checked prior to inflation with molding. Other radioopaque markers could be used as necessary to facilitate positioning of hip prosthesis  30 . A marker at the base of femoral neck  14  could be one such marker. 
     Deflated femoral head component  28   a  may be inflated with air or water prior to injection of molding in order to visualize femoral head component  28  in its inflated state to ascertain positioning. An additional embodiment of hip prosthesis  30  includes inflating deflated femoral head component  28   a  with water or air prior to cementation to incorporate small fenestrations (typically 2-3 mm diameter) along femoral component  26 . The small fenestrations would allow molding to escape the device and interdigitate with the patient&#39;s bone, which is the normal mode by which molding, such as bone cement, achieves fixation. 
     Insertion of the distal portion of femoral component  26  into femoral canal  22  of the patient can be performed in several ways. An embodiment, as depicted in  FIG. 9 , involves femoral component  26  and femoral head component  28   a  initially rolled lengthwise into a slimmer form to facilitate insertion into the patient. 
     External sleeve  32  on the outside of femoral component  26  allows for placement of flexible tube  34  to be inserted down femoral canal  22  adjacent to femoral component  26 , as shown in  FIGS. 10-12 . This positioning is aided by use of guide tube  18  previously used for trajectory guidance of flexible reamers  16  with 90° elbow  20 , as shown in  FIG. 12 . External sleeve  32  can be collapsible so that when molding is introduced into femoral canal  22 , external sleeve  32  will not prevent complete inflation of femoral component  26  with molding. 
     Femoral head portion  28  of hip prosthesis  30  includes insertion sleeve  33  over the top portion of deflated femoral head component  28   a  when in its rolled-up form, as shown in  FIGS. 12 and 13 . Insertion sleeve  33  has string  36  attached to the end of sleeve  33  at a proximal aspect of femoral head component  28 . Sleeve  33  can be manufactured so that its diameter about femoral neck  14  is smaller than the diameter of deflated femoral head component  28   a , thereby allowing sleeve  33  to be pulled with substantial force, in turn allowing sleeve  33  and femoral head component  28   a  to be introduced into acetabulum  8 . 
     After insertion of the distal portion of femoral component  26  into femoral canal  22 , string  36  can be passed through lateral thigh incision  10  into acetabulum  8  where string  36  can be visualized with an arthroscope. A grasper (not shown) inserted into one of the arthroscopic portals  2   a ,  2   b ,  2   c  can then be used to pull string  36  through the portal  2   a ,  2   b ,  2   c  and bring insertion sleeve  33  containing the femoral head component  28   a  into acetabulum  8 , as shown in  FIG. 14 . 
     Insertion sleeve  33  can be manufactured to include tab  38  on sleeve  33 . Tab  38  can be pulled by an arthroscopic grasper (not shown) through arthroscopic portal  2   a ,  2   b ,  2   c  after introduction of the deflated femoral head component  28   a  into acetabulum  8 , as shown in  FIG. 13 . This releases the narrow base of sleeve  33  over the femoral head component  28   a  and allows sleeve  33  to be pulled through arthroscopic portal  2   a ,  2   b ,  2   c  with attached string  36  and removed from the body. 
     Positioning of femoral component  26  and deflated femoral head component  28   a  can be confirmed with fluoroscopy. Deflated femoral head component  28   a  may then be injected with molding, resulting in inflated femoral head component  28   b , as depicted in  FIG. 15 . 
     The indications and candidates for this procedure include non-ambulatory patients with hip fracture or patients with limited ambulatory capacity and hip fracture. This procedure would be less invasive than hip hemiarthroplasty. This procedure provides better pain relief than hip pinning, which requires a significant amount of healing prior to pain relief. Better pain relief would allow patients to begin transfers in position sooner than with hip pinning. Early ambulation after hip fracture is known to decrease complications such as deep venous thrombosis and pulmonary emboli. 
     Benefits of this procedure when compared to hip pinning are that patients would have pain relief similar to that experienced with a hemiarthroplasty without the protracted healing period required with hip pinning. 
     Benefits of this procedure when compared to hip hemiarthroplasty are that it is less invasive, and there is no violation of hip capsule with significantly less risk of hip dislocation. This feature would be especially beneficial in patients with dementia and neuromuscular disorders that dispose to dislocation. 
     It will thus be seen that the objects set forth above, and those made apparent from the foregoing disclosure, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing disclosure or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween.