REFERENCE TO PENDING PRIOR PATENT APPLICATION 
     This patent application claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 61/782,827, filed Mar. 14, 2013 by Julian Nikolchev et al. for METHOD AND APPARATUS FOR RECONSTRUCTING A HIP JOINT, INCLUDING THE PROVISION AND USE OF A NOVEL INTRAJOINT ARTHROSCOPIC DEBRIDEMENT TEMPLATE FOR ASSISTING IN THE TREATMENT OF CAM-TYPE FEMOROACETABULAR IMPINGEMENT (FAI), which patent application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to surgical methods and apparatus in general, and more particularly to surgical methods and apparatus for reconstructing a hip joint. 
     BACKGROUND OF THE INVENTION 
     The hip joint movably connects the leg to the torso. The hip joint is a ball-and-socket joint, and is capable of a wide range of different motions, e.g., flexion and extension, abduction and adduction, medial and lateral rotation, etc. See  FIG. 1 . With the possible exception of the shoulder joint, the hip joint is perhaps the most mobile joint in the body. Significantly, and unlike the shoulder joint, the hip joint carries substantial weight loads during most of the day, in both static (e.g., standing and sitting) and dynamic (e.g., walking and running) conditions. 
     The hip joint is susceptible to a number of different pathologies. These pathologies can have both congenital and injury-related origins. In some cases, the pathology can be substantial at the outset. In other cases, the pathology may be minor at the outset but, if left untreated, may worsen over time. More particularly, in many cases an existing pathology may be exacerbated by the dynamic nature of the hip joint and the substantial weight loads imposed on the hip joint. 
     The pathology may, either initially or thereafter, significantly interfere with patient comfort and lifestyle. In some cases the pathology can be so severe as to require partial or total hip replacement. A number of procedures have been developed for treating hip pathologies short of partial or total hip replacement, but these procedures are generally limited in scope due to the significant difficulties associated with treating the hip joint. 
     A better understanding of various hip joint pathologies, and also the current limitations associated with their treatment, can be gained from a more precise understanding of the anatomy of the hip joint. 
     Anatomy of the Hip Joint 
     The hip joint is formed at the junction of the femur and the hip. More particularly, and looking now at  FIG. 2 , the ball of the femur is received in the acetabular cup of the hip, with a plurality of ligaments and other soft tissue serving to hold the bones in articulating condition. 
     More particularly, and looking now at  FIG. 3 , the femur is generally characterized by an elongated body terminating, at its top end, in an angled neck which supports a hemispherical head (also sometimes referred to as the ball). As seen in  FIGS. 3 and 4 , a large projection known as the greater trochanter protrudes laterally and posteriorly from the elongated body adjacent to the neck. A second, somewhat smaller projection known as the lesser trochanter protrudes medially and posteriorly from the elongated body adjacent to the neck. An intertrochanteric crest ( FIGS. 3 and 4 ) extends along the periphery of the femur, between the greater trochanter and the lesser trochanter. 
     Looking next at  FIG. 5 , the hip is made up of three constituent bones: the ilium, the ischium and the  pubis . These three bones cooperate with one another (they typically ossify into a single “hip bone” structure by the age of 25) so as to form the acetabular cup. The acetabular cup receives the head of the femur. 
     Both the head of the femur and the acetabular cup are covered with a layer of articular cartilage which protects the underlying bone and facilitates motion. See  FIG. 6 . 
     Various ligaments and soft tissue serve to hold the ball of the femur in place within the acetabular cup. More particularly, and looking now at  FIGS. 7 and 8 , the ligamentum teres extends between the ball of the femur and the base of the acetabular cup. As seen in  FIG. 9 , a labrum is disposed about the perimeter of the acetabular cup. The labrum serves to increase the depth of the acetabular cup and effectively establishes a suction seal between the ball of the femur and the rim of the acetabular cup, thereby helping to hold the head of the femur in the acetabular cup. In addition, and looking now at  FIG. 10 , a fibrous capsule extends between the neck of the femur and the rim of the acetabular cup, effectively sealing off the ball-and-socket members of the hip joint from the remainder of the body. The foregoing structures are encompassed and reinforced by a set of three main ligaments (i.e., the iliofemoral ligament, the ischiofemoral ligament and the pubofemoral ligament) which extend between the femur and the hip. See  FIGS. 11 and 12 . 
     Pathologies of the Hip Joint 
     As noted above, the hip joint is susceptible to a number of different pathologies. These pathologies can have both congenital and injury-related origins. 
     By way of example but not limitation, one important type of congenital pathology of the hip joint involves impingement between the neck of the femur and the rim of the acetabular cup. In some cases, and looking now at  FIG. 13 , this impingement can occur due to irregularities in the geometry of the femur. This type of impingement is sometimes referred to as a cam-type femoroacetabular impingement (i.e., a cam-type FAI). In other cases, and looking now at  FIG. 14 , the impingement can occur due to irregularities in the geometry of the acetabular cup. This latter type of impingement is sometimes referred to as a pincer-type femoroacetabular impingement (i.e., a pincer-type FAI). Impingement can result in a reduced range of motion, substantial pain and, in some cases, significant deterioration of the hip joint. 
     By way of further example but not limitation, another important type of congenital pathology of the hip joint involves defects in the articular surface of the ball and/or the articular surface of the acetabular cup. Defects of this type sometimes start out fairly small but often increase in size over time, generally due to the dynamic nature of the hip joint and also due to the weight-bearing nature of the hip joint. Articular defects can result in substantial pain, induce or exacerbate arthritic conditions and, in some cases, cause significant deterioration of the hip joint. 
     By way of further example but not limitation, one important type of injury-related pathology of the hip joint involves trauma to the labrum. More particularly, in many cases, an accident or a sports-related injury can result in the labrum being torn away from the rim of the acetabular cup, typically with a tear running through the body of the labrum. See  FIG. 15 . These types of injuries can be very painful for the patient and, if left untreated, can lead to substantial deterioration of the hip joint. 
     The General Trend Toward Treating Joint Pathologies Using Minimally-Invasive, and Earlier, Interventions 
     The current trend in orthopedic surgery is to treat joint pathologies using minimally-invasive techniques. By way of example but not limitation, it is common to re-attach ligaments in the shoulder joint using minimally-invasive, “keyhole” techniques which do not require laying open the capsule of the shoulder joint. By way of further example but not limitation, it is common to repair torn meniscal cartilage in the knee joint, and/or to replace ruptured ACL ligaments in the knee joint, using minimally-invasive techniques. While such minimally-invasive approaches can require additional training on the part of the surgeon, such procedures generally offer substantial advantages for the patient and have now become the standard of care for many shoulder joint and knee joint pathologies. 
     In addition to the foregoing, due to the widespread availability of minimally-invasive approaches for treating pathologies of the shoulder joint and knee joint, the current trend is to provide such treatment much earlier in the lifecycle of the pathology, so as to address patient pain as soon as possible and so as to minimize any exacerbation of the pathology itself. This is in marked contrast to traditional surgical practices, which have generally dictated postponing surgical procedures as long as possible so as to spare the patient from the substantial trauma generally associated with invasive surgery. 
     Treatment for Pathologies of the Hip Joint 
     Unfortunately, minimally-invasive treatments for pathologies of the hip joint have lagged far behind minimally-invasive treatments for pathologies of the shoulder joint and knee joint. This is generally due to (i) the geometry of the hip joint itself, and (ii) the nature of the pathologies which must typically be addressed in the hip joint. 
     More particularly, the hip joint is generally considered to be a “tight” joint, in the sense that there is relatively little room to maneuver within the confines of the joint itself. This is in marked contrast to the knee joint, which is generally considered to be relatively spacious when compared to the hip joint. As a result, it is relatively difficult for surgeons to perform minimally-invasive procedures on the hip joint. 
     Furthermore, the natural pathways for entering the interior of the hip joint (i.e., the pathways which naturally exist between adjacent bones) are generally much more constraining for the hip joint than for the shoulder joint or the knee joint. This limited access further complicates effectively performing minimally-invasive procedures on the hip joint. 
     In addition to the foregoing, the nature and location of the pathologies of the hip joint also complicate performing minimally-invasive procedures. By way of example but not limitation, consider a typical detachment of the labrum in the hip joint. In this situation, instruments must generally be introduced into the joint space using an angle of approach which is set at approximately a right angle to the angle of re-attachment. This makes drilling into bone, for example, much more complex than where the angle of approach is effectively aligned with the angle of re-attachment, such as is frequently the case in the shoulder joint. Furthermore, the working space within the hip joint is typically extremely limited, further complicating repairs where the angle of approach is not aligned with the angle of re-attachment. 
     As a result of the foregoing, minimally-invasive hip joint procedures are still relatively difficult, and patients must frequently manage their hip joint pathologies for as long as possible, until a partial or total hip replacement can no longer be avoided, whereupon the procedure is generally done as a highly-invasive, open procedure, with all of the disadvantages associated with highly-invasive, open procedures. 
     As a result, there is a pressing need for improved methods and apparatus for reconstructing the hip joint. 
     Issues Relating to the Treatment of Cam-Type Femoroacetabular Impingement 
     As noted above, hip arthroscopy is becoming increasingly more common in the diagnosis and treatment of various hip pathologies. However, due to the anatomy of the hip joint and the pathologies associated with the same, hip arthroscopy is currently practical for only selected pathologies and, even then, hip arthroscopy has generally met with limited success. 
     One procedure which is sometimes attempted arthroscopically relates to femoral debridement for treatment of cam-type femoroacetabular impingement (i.e., cam-type FAI). More particularly, with cam-type femoroacetabular impingement, irregularities in the geometry of the femur can lead to impingement between the femur and the rim of the acetabular cup. Treatment for cam-type femoroacetabular impingement typically involves debriding the femoral neck and/or head, using tools such as burrs, to remove the bony deformities causing the impingement. In this respect it should be appreciated that it is important to debride the femur carefully, since only bone which does not conform to the desired geometry should be removed, in order to ensure positive results as well as to minimize the possibility of bone fracture after treatment. 
     For this reason, when debridement is performed as an open surgical procedure, surgeons generally use pre-shaped curvature templates to guide them in removing the appropriate amount of bone from the femur. 
     However, when the debridement procedure is attempted arthroscopically, conventional curvature templates cannot be passed through the narrow keyhole incision, and hence debridement templates are not available to the surgeon for reshaping the bone surface. As a result, the debridement must be effected freehand. In this setting, it is generally quite difficult for the surgeon to determine exactly how much bone should be removed, and whether the shape of the remaining bone has the desired geometry. 
     Accordingly, a primary object of the present invention is to provide the surgeon with arthroscopic debridement templates which can be used during an arthroscopic debridement procedure to treat cam-type femoroacetabular impingement. 
     SUMMARY OF THE INVENTION 
     The present invention comprises the provision and use of a novel arthroscopic debridement template which can be used during an arthroscopic debridement procedure to treat cam-type femoroacetabular impingement. 
     In one preferred form of the invention, there is provided apparatus for use in debriding a bone, said apparatus comprising: 
     an arthroscopic debridement template comprising a body reconfigurable between (i) a first configuration having a first profile and comprising an arc matching the desired curvature of the bone after debridement, and (ii) a second configuration having a second profile, wherein said second profile is smaller than said first profile. 
     In another preferred form of the invention, there is provided apparatus for use in debriding a bone, said apparatus comprising: 
     an arthroscopic debridement template comprising a plurality of fingers reconfigurable between (i) a first configuration having a first profile and defining an arc matching the desired curvature of the bone after debridement, and (ii) a second configuration having a second profile, wherein said second profile is smaller than said first profile. 
     In another preferred form of the invention, there is provided apparatus for use in debriding a bone, said apparatus comprising: 
     an elongated body comprising at least one light-emitting element for projecting an optical arthroscopic debridement template onto the bone, wherein said optical arthroscopic debridement template comprises a first pattern when projected onto an area of the bone having a regular surface and a second pattern when projected onto an area of the bone having an irregular surface. 
     In another preferred form of the invention, there is provided apparatus for use in debriding a bone, said apparatus comprising: 
     an arthroscopic debridement template comprising at least one marker for disposition within the bone, wherein said at least one marker comprises a body discernable from bone. 
     In another preferred form of the invention, there is provided a method for debriding a bone, said method comprising: 
     providing apparatus comprising: 
     an arthroscopic debridement template comprising a body reconfigurable between (i) a first configuration having a first profile and comprising an arc matching the desired curvature of the bone after debridement, and (ii) a second configuration having a second profile, wherein said second profile is smaller than said first profile; 
     configuring said arthroscopic debridement template in said second configuration; 
     advancing said arthroscopic debridement template to a debridement site; 
     reconfiguring said arthroscopic debridement template from said second configuration to said first configuration; and 
     debriding the bone using said arthroscopic debridement template for guidance. 
     In another preferred form of the invention, there is provided a method for debriding a bone, said method comprising: 
     providing apparatus comprising: 
     an arthroscopic debridement template comprising a plurality of fingers reconfigurable between (i) a first configuration having a first profile and defining an arc matching the desired curvature of the bone after debridement, and (ii) a second configuration having a second profile, wherein said second profile is smaller than said first profile; 
     configuring said arthroscopic debridement template in said second configuration; 
     advancing said arthroscopic debridement template to a debridement site; 
     reconfiguring said arthroscopic debridement template from said second configuration to said first configuration; and 
     debriding the bone using said arthroscopic debridement template for guidance. 
     In another preferred form of the invention, there is provided a method for debriding a bone, said method comprising: 
     providing apparatus comprising: 
     an elongated body comprising at least one light-emitting element for projecting an optical arthroscopic debridement template onto the bone, wherein said optical arthroscopic debridement template comprises a first pattern when projected onto an area of the bone having a regular surface and a second pattern when projected onto an area of the bone having an irregular surface; 
     projecting said optical arthroscopic debridement template onto the bone; 
     debriding the bone using said arthroscopic debridement template for guidance. 
     In another preferred form of the invention, there is provided a method for debriding a bone, said method comprising: 
     providing apparatus comprising: 
     an arthroscopic debridement template comprising at least one marker for disposition within the bone, wherein said at least one marker comprises a body discernable from bone; 
     positioning said at least one marker within the bone that is to be debrided, said at least one marker being set so as to demarcate at least one of (i) the area of bone to be debrided, and (ii) the depth of bone to be debrided; and 
     debriding the bone using said arthroscopic debridement template for guidance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
         FIGS. 1A-1D  are schematic views showing various aspects of hip motion; 
         FIG. 2  is a schematic view showing bone structures in the region of the hip joint; 
         FIG. 3  is a schematic anterior view of the femur; 
         FIG. 4  is a schematic posterior view of the top end of the femur; 
         FIG. 5  is a schematic view of the pelvis; 
         FIGS. 6-12  are schematic views showing bone and soft tissue structures in the region of the hip joint; 
         FIG. 13  is a schematic view showing cam-type femoroacetabular impingement (i.e., cam-type FAI); 
         FIG. 14  is a schematic view showing pincer-type femoroacetabular impingement (i.e., pincer-type FAI); 
         FIG. 15  is a schematic view showing a labral tear; 
         FIG. 16  is a schematic view showing the head and neck of a femur and a cam-type femeroacetabular impingement site; 
         FIG. 17  is a schematic view of an arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 17A-17C  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 18A and 18B  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 19A and 19B  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIG. 20  is a schematic view of an arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 20A and 20B  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 21-24  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 25-28  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 29-32  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIG. 33  is a schematic view of an arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 34-36  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 37 and 38  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIG. 39  is a schematic view of an arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 39A and 39B  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; 
         FIGS. 40-43  are schematic views of another arthroscopic debridement template formed in accordance with the present invention; and 
         FIGS. 44-46  are schematic views of another arthroscopic debridement template formed in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention comprises the provision and use of a novel arthroscopic debridement template which can be used during an arthroscopic debridement procedure to treat cam-type femoroacetabular impingement. 
     As will hereinafter be discussed, the present invention provides mechanical arthroscopic debridement templates, optical arthroscopic debridement templates and arthroscopic debridement templates incorporating a bone cutting tool. 
     Mechanical Arthroscopic Debridement Templates 
     In one preferred form of the invention, there is provided a mechanical arthroscopic debridement template. In this form of the invention, the arthroscopic debridement template is mounted on the distal end of an insertable tool and the arthroscopic debridement template is capable of being reconfigurable between (i) a reduced configuration so that the arthroscopic debridement template may be moved to, and withdrawn from, an arthroscopic surgical site, and (ii) an expanded configuration so that the arthroscopic debridement template may provide guidance to the surgeon during the bone reshaping process. 
     In one preferred form of the invention, the arthroscopic debridement template is mounted on the distal end of an insertable tool so that (i) the arthroscopic debridement template can be retracted into the insertable tool when the arthroscopic debridement template is to be moved to, and removed from, the surgical site, and (ii) the arthroscopic debridement template can be projected out of the distal end of the insertable tool when the arthroscopic debridement template is to be used at the surgical site (e.g., at the femoral neck, at the femoral head, at the transition between the femoral neck and the femoral head, etc.) so as to guide a surgeon in reshaping the bone surface. 
     The foregoing approach facilitates introducing the arthroscopic debridement template to the surgical site through a narrow keyhole incision, yet permits the arthroscopic debridement template to be expanded to its full working shape at the surgical site for use during the debridement procedure. Among other things, the apparatus is preferably configured so that the apparatus can be introduced through a standard arthroscopic access cannula (e.g., 4 mm to 8.5 mm in diameter), and the apparatus is preferably configured so that the apparatus can be articulated and manipulated as necessary so that the arthroscopic debridement template can be appropriately positioned adjacent to the bone which is to be debrided. 
     In one preferred form of the invention, the surgeon is provided with a kit comprising various arthroscopic debridement templates, with the various arthroscopic debridement templates being sized to address a variety of different patient anatomies. In one form of the invention, the various arthroscopic debridement templates are each provided with their own associated insertable tool. In another form of the invention, the various arthroscopic debridement templates can be selectively mated to a common insertable tool. 
     The arthroscopic debridement template of the present invention can be formed with a variety of constructions without departing from the scope of the present invention. A number of these exemplary constructions will now be discussed in greater detail. 
     More particularly,  FIG. 16  shows a schematic view of a femur  5  comprising a femoral head  7  and a femoral neck  8 , and illustrates a cam-type femoroacetabular impingement site  10  which needs to be debrided in order to treat the cam-type femoroacetabular impingement. 
       FIG. 17  shows a one-piece arthroscopic debridement template  15 . Arthroscopic debridement template  15  is mounted at the distal end of a shaft  20  and is advanced through an arthroscopic access cannula  25  to the impingement site  10  (e.g., at the femoral neck, at the femoral head, at the transition between the femoral neck and the femoral head, etc.). The one-piece arthroscopic debridement template  15  is formed with a pre-determined curved geometry which matches the desired bone geometry. Thus, during debridement, arthroscopic debridement template  15  can be placed directly against the bone. This allows the surgeon to compare the patient&#39;s current bone geometry with the desired bone geometry (which is reflected by the configuration of arthroscopic debridement template  15 ) and, in the process, to be guided with respect to the amount of bone which is to be removed. In order to permit arthroscopic debridement template  15  to be passed through the narrow arthroscopic access cannula  25 , arthroscopic debridement template  15  is preferably formed out of an elastic material (e.g., a superelastic material such as Nitinol). This permits arthroscopic debridement template  15  to assume one configuration (e.g., long and narrow) while passing through arthroscopic access cannula  25 , and then assume another configuration (e.g., broad and curved) when at the surgical site. 
     In another form of the present invention, and looking now at  FIGS. 17A-17C , the novel apparatus comprises a multi-component construction whereby arthroscopic debridement template  15  is secured to a shaft  20  and telescopically housed in an inserter tube  30  which fits through arthroscopic access cannula  25 . Arthroscopic debridement template  15  is retracted within inserter tube  30  during delivery into the joint space ( FIG. 17A ) in order to facilitate passage through arthroscopic access cannula  25  and patient anatomy, then extended from inserter tube  30  ( FIG. 17B ) for use in a bone debridement procedure at the arthroscopic site. 
     In one form of the invention, arthroscopic debridement template  15  may be aligned with the longitudinal axis of inserter tube  30  (see  FIGS. 17A and 17B ). Alternatively, in another form of the invention, arthroscopic debridement template  15  may be disposed out of alignment with the longitudinal axis of inserter tube  30  (see  FIG. 17C ). In such a construction, and looking now at  FIG. 17C , arthroscopic debridement template  15  may be biased so as to extend laterally away from the longitudinal axis of inserter tube  30  as arthroscopic debridement template  15  is extended out of inserter tube  30 . This construction can be particularly useful where the angle of approach to the surgical site (which is generally dictated by the disposition of arthroscopic cannula  25  within the anatomy) is different from the angle at which arthroscopic debridement template  15  must address the bone. 
       FIGS. 18A and 18B  show another configuration for the arthroscopic debridement template  15  of the present invention. More particularly, in this form of the invention, arthroscopic debridement template  15  is formed out of a plurality of fingers (and/or arms)  35  which, in their open configuration ( FIG. 18A ), collectively form a fan-like structure which is reflective of the desired bone geometry, but which, when in their closed configuration ( FIG. 18B ), form a narrow bundle-like structure which can be passed through arthroscopic access cannula  25 . To this end, fingers  35  are preferably formed out of an elastic material (e.g., a superelastic material such as Nitinol). If desired, the distal ends of two or more of the fingers  35  may be connected together by a filament  37  ( FIG. 18A ) so as to provide further definition to the fan-like structure collectively defined by fingers  35 . 
     In one preferred form of the invention, the plurality of fingers  35  are telescopically housed in an inserter tube  40  during delivery to the joint space (see  FIG. 19A ). Once inside the joint space, the plurality of fingers  35  are extended out of inserter tube  40  so as to form the fan-like structure ( FIG. 19B ) which is to be placed against the bone surface to serve as an arthroscopic debridement template (see  FIG. 18A ). In this form of the invention, the plurality of fingers  35  are extended out of inserter tube  40  so as to create a single collective structure which can be placed on the bone surface which is to be debrided, whereby to act as a template for the bone debridement procedure. 
     In one form of the present invention, each of the fingers  35  extends out of inserter tube  40  so as to form a structure of constant radius. In another form of the present invention, each of the fingers  35  extends out of inserter tube  40  so as to form a collective structure of varying radius and/or a compound curve. In yet another form of the present invention, each of the fingers  35  may be variably extended out of inserter tube  40  to various longitudinal positions, whereby to form a collective structure having a variety of radii and/or shapes according to the extent to which each finger  35  is extended out of inserter tube  40 . By way of example but not limitation, each of the fingers  35  may have 2 or more longitudinal positions relative to inserter tube  40 , wherein each longitudinal position has a different radius of curvature. 
     In another form of the present invention, and looking now at  FIG. 20 , arthroscopic debridement template  15  comprises an arc  45  of fixed curvature, wherein arthroscopic debridement template  15  is pivotally mounted to the distal end of a shaft  20 . In this form of the invention, arc  45  of arthroscopic debridement template  15  is formed with a pre-determined curved geometry which matches the desired bone geometry. Thus, during the debridement procedure (e.g., at the femoral neck, at the femoral head, at the transition between the femoral neck and the femoral head, etc.), arthroscopic debridement template  15  can be placed against the bone which is to be debrided so that arc  45  of the arthroscopic debridement template  15  sits adjacent to the bone. This allows the surgeon to compare the patient&#39;s current bone geometry with the desired bone geometry (which is reflected by arc  45  of arthroscopic debridement template  15 ), whereby to guide the surgeon in determining the appropriate amount of bone to be debrided. 
     During the debridement procedure, shaft  20  is used to advance arthroscopic debridement template  15  through an arthroscopic access cannula  25  to the impingement site, so that arc  45  of arthroscopic debridement template  15  approaches the bone (e.g., the femoral neck  8  as shown in  FIG. 20 ). Arc  45  of arthroscopic debridement template  15  may then be pressed up against the bone, such that the surgeon can compare the geometry of the native bone to the geometry desired for the bone (i.e., the curvature of arc  45 ). 
     In order to facilitate passage of arthroscopic debridement template  15  through the arthroscopic access cannula  25  and to assist advancing arthroscopic debridement template  15  to the surgical site, arthroscopic debridement template  15  is preferably pivotally connected to the distal end of shaft  20  (e.g., by a pivot pin  46 ), and the apparatus may further comprise control means  47  (e.g., control wires, push rods, etc. of the sort well known in the art) connecting arthroscopic debridement template  15  to the proximal end of shaft  20  (not shown), so that the surgeon can adjust the disposition of arthroscopic debridement template  15  (and hence adjust the disposition of its arc  45 ) relative to shaft  20  during the debridement procedure. 
     It should also be appreciated that, if desired, arthroscopic debridement template  15  can be formed out of a flexible material, and additional control means  48  (e.g., control wires, push rods, etc. of the sort well known in the art) provided, so as to permit the surgeon to alter the curvature of arc  45 , whereby to facilitate advancement of arthroscopic debridement template  15  to the surgical site and/or to allow the curvature of arc  45  to be modified in situ so as to better guide the surgeon in the desired debridement of the bone. In this form of the invention, the additional control means  48  (e.g., control wires, push rods, etc.) which are provided on the apparatus so as to permit the surgeon to alter the curvature of arc  45  are preferably connected to a handle or trigger (not shown) disposed at the proximal end of shaft  20  for appropriate actuation by the surgeon. 
     Additionally, arthroscopic debridement template  15  may be removable from shaft  20 , so that the surgeon can exchange one arthroscopic debridement template  15  having a given arc  45  for a different arthroscopic debridement template  15  having a different arc  45 . In this form of the invention, arthroscopic debridement template  15  may be reusable or disposable. Furthermore, if desired, arthroscopic debridement template  15  may incorporate a light source  49  for better visualization of the debridement site. 
     In another form of the present invention, and looking now at  FIGS. 20A and 20B , the arthroscopic debridement template  15  is generally similar to the arthroscopic debridement template  15  shown in  FIG. 20 , except that arthroscopic debridement template  15  is formed with a reduced profile so as to facilitate delivery to, and removal from, the arthroscopic site. In this form of the invention, when arthroscopic debridement template  15  is passed through an arthroscopic access cannula  25 , arthroscopic debridement template  15  is substantially longitudinally aligned with shaft  20  ( FIG. 20A ). Once arthroscopic debridement template  15  has been passed through the arthroscopic access cannula, the arthroscopic debridement template  15  may be pivoted so as to align its arc  45  with the target bone surface ( FIG. 20B ). 
     Arthroscopic debridement template  15  may also be telescopically housed in an inserter tube  50  such that when arthroscopic debridement template  15  is passed to and from the joint (e.g., through arthroscopic access cannula  25 ), arthroscopic debridement template  15  is housed within inserter tube  50 , and when arthroscopic debridement template  15  is in the joint, arthroscopic debridement template  15  is extended out of inserter tube  50 . 
     In another form of the present invention, and looking now at  FIGS. 21, 22A, 22B, 23A, 23B and 24 , arthroscopic debridement template  15  may comprise a flexible tip  52 , formed integral with, or attached to, the distal end of a substantially rigid shaft  55 . In this form of the invention, a handle  60  is disposed on the proximal end of shaft  55  so as to allow the surgeon to adjust the curvature of flexible tip  52  by pulling/pushing a trigger  65  mounted on handle  60  (e.g., which operates control wires, push rods, etc. of the sort well known in the art, not shown, which connect flexible tip  52  to trigger  65 ). In this way the curvature of flexible tip  52  can be adjusted so as to reflect the desired bone geometry. In one preferred form of the invention, handle  60  and trigger  65  incorporate a ratchet mechanism such that when the desired curvature is reached, the trigger can be released and the apparatus remains locked in position, with flexible tip  52  in the desired position. In this form of the invention, a release is provided so as to allow the apparatus to return to its starting configuration when desired. Such ratchet mechanisms and releases are well known in the art of handles and triggers. Handle  60  may further include markings  70  to indicate the degree of curvature of flexible tip  52  when trigger  65  is actuated. See  FIG. 21 . 
     During the debridement procedure, and looking now at  FIGS. 22A, 22B, 23A and 23B , the shaft  55  carrying flexible tip  52  is advanced through an arthroscopic access cannula to the impingement site  10  (e.g., at the femoral neck, at the femoral head, at the transition between the femoral neck and the femoral head, etc.), and then the surgeon adjusts the degree of curvature of flexible tip  52  (using trigger  65  on handle  60 ) so that flexible tip  52  forms an arc reflecting the desired bone geometry. The thus-configured flexible tip  52  may then be positioned adjacent to the impinging bone  10  and used by the surgeon to guide the desired bone debridement. 
     In one preferred form of the invention, flexible tip  52  is able to articulate in different directions ( FIG. 24 ) relative to the longitudinal axis of shaft  55  (e.g., up, down, left, right, etc.) so as to provide the surgeon with more options for approaching the impingement site—such a construction can be particularly desirable in a joint where the angle of approach is restricted and/or in a “tight” joint where workspace is limited (e.g., inside the hip joint). 
     Optical Arthroscopic Debridement Templates 
     In another form of the present invention, and looking now at  FIGS. 25-28 , arthroscopic debridement template  15  may comprise the flexible tip  52  construction shown in  FIGS. 21-24  and may further include one or more lights  75  disposed in and/or along the length of flexible tip  52  so as to aid the surgeon in determining where and how much bone is to be debrided. More particularly, in this form of the invention, and looking now at  FIG. 26 , one or more lights  75  are directed toward the surface of the bone from the inner surface  80  of the arc formed by flexible tip  52 . The light(s)  75  may be recessed within inner surface  80  of flexible tip  52  and/or light(s)  75  may be flush with inner surface  80  of flexible tip  52 . In one form of the invention, light(s)  75  may be active elements (e.g., LEDs) disposed at flexible tip  52 . In another form of the invention, light(s)  75  may be the distal end(s) of light fiber(s) extending through shaft  55  and flexible tip  52 , with the source of the light (not shown) disposed in handle  60  of the apparatus, such that the light generated at the light source is transmitted to the distal end of shaft  55  by the light fiber(s). 
     During the debridement procedure, and looking now at  FIGS. 27 and 28 , the shaft  55  carrying flexible tip  52  is advanced by the surgeon through an arthroscopic access cannula to the impingement site  10  (e.g., at the femoral neck, at the femoral head, at the transition between the femoral neck and the femoral head, etc.), and then the surgeon adjusts the curvature of flexible tip  52  (e.g., using trigger  65 ) so that the curvature of flexible tip  52  properly reflects the desired bone geometry. The surgeon then advances flexible tip  52  so that flexible tip  52  is disposed adjacent to the bone which is to be debrided, with the inner surface  80  of flexible tip  52  forming an arc which represents the desired geometry for the bone. When light(s)  75  are activated, light is emitted from light(s)  75  in the arc of flexible tip  52  and is directed toward the surface of the bone. Where flexible tip  52  is flush with the surface of the bone, no light will be seen, and where flexible tip  52  is spaced from the bone, light will be visible (i.e., due to the light reflecting off the bone and visible through the space formed between flexible tip  52  and the bone), thereby assisting the surgeon in identifying how the curvature of the native bone differs from the desired geometry and providing guidance as to how much bone is to be debrided. 
     In another form of the present invention, and looking now at  FIGS. 29-32 , flexible tip  52  is formed so that the light from light(s)  75  is emitted perpendicular to the radius of curvature of the arc formed by a bent flexible tip  52  (i.e., at a 90° angle to the inner surface  80  of the arc). In this form of the invention, when flexible tip  52  has been appropriately configured and its inner surface  80  is pressed up against the surface of the bone which is to be debrided, the light from light(s)  75  travels along the surface of the bone (i.e., sideways from flexible tip  52 ). Where there is a spur or “bump” in the bone, indicative of an impingement site, passage of the light from light(s)  75  is blocked, thereby indicating a portion of the bone to be debrided. See  FIGS. 31 and 32 . It should be appreciated that the light may be emitted from one or both sides of flexible tip  52 , as desired. 
     In another form of the present invention, and looking now at  FIG. 33 , arthroscopic debridement template  15  is a light pattern projected onto the surface of the bone. More particularly, in this form of the invention, the apparatus (e.g., flexible tip  52 ) is constructed so as to project a light pattern onto the surface of the bone so as to assist the surgeon in locating the impingement site(s)  10  to be debrided. More particularly, in this form of the invention, a light pattern  85  (e.g., a grid, parallel lines, dots, squiggles, concentric circles, etc.) is projected onto the surface of the bone. Where the topography of the surface of the bone varies (e.g., where the surface of the bone is raised at a point of impingement), the light pattern  85  is modified by the irregular topography of the bone. By way of example but not limitation, when the light pattern  85  is directed onto a portion of the bone including a bony protrusion (e.g., a bone “spur”) such as that which may cause impingement, the projected light pattern  85  is modified by the bump (e.g., such as by going from linear to non-linear, in the manner shown in  FIG. 33 ), indicating to the surgeon the location of the bony protrusion. 
     If desired, and looking now at  FIGS. 34-36 , arthroscopic debridgement template  15  may comprise a light pattern formed by two converging beams of light  90 ,  95  generated by light sources  97 ,  98  (e.g., light sources carried by flexible tip  52 ). In this form of the invention, the two converging beams of light  90 ,  95  are directed onto the surface of the bone, with the two beams of light set so that they are directed onto a common point  100  (i.e., the “focal point”) on the surface of the bone. The focal point  100  is selected so that it is set at a predetermined distance from the sources  97 ,  98  of the two converging beams of light  90 ,  95 . As a result, when the arthroscopic debridement template  15  is positioned next to the bone so that the two converging beams of light  90 ,  95  form a single point  100  ( FIGS. 34 and 35 ), and the arthroscopic debridement template  15  is thereafter moved laterally along the bone, the converging beams of light  90 ,  95  will remain “in focus” (i.e., forming a single point of light  100 ) as long as the surface of the bone is uniform, and the converging beams of light  90 ,  95  will move “out of focus” (e.g., into a pair of separated points  100 A,  100 B, in the manner shown in  FIG. 36 ) at those points where the surface of the bone varies in elevation (e.g., at bony protrusions or bumps which may cause impingement). In this way, arthroscopic debridement template  15  serves to identify impingement points  10  to the surgeon. 
     In another form of the present invention, and looking now at  FIGS. 37 and 38 , arthroscopic debridement template  15  may comprise a light pattern formed by two converging lines of light  105 ,  110  generated by light sources  112 ,  113  (e.g., light sources carried by flexible tip  52 ). In this form of the invention, the two converging lines of light  105 ,  110  are directed onto the surface of the bone, with the two lines of light  105 ,  110  set so that they are directed onto a common location  115  (i.e., the “focal point”) on the surface of the bone. The focal point  115  is selected so that it is set at a predetermined distance from the sources  112 ,  113  of the two converging lines of light  105 ,  110 . As a result, when arthroscopic debridement template  15  is positioned next to the bone so that the two converging lines of light  105 ,  110  form a single line  115  ( FIG. 37 ), and the arthroscopic debridement template  15  is thereafter moved laterally along the bone, the converging lines of light  105 ,  110  will remain “in focus” (i.e., forming a single line of light  115 ) as long as the surface of the bone is uniform, and the converging lines of light  105 ,  110  will move “out of focus” (e.g., into a pair of separated lines  115 A,  115 B, in the manner shown in  FIG. 38 ) at those points where the surface of the bone varies in elevation (e.g., at bony protrusions or bumps which may cause impingement). In other words, with this form of the present invention, arthroscopic debridement template  15  is configured so as to display a single line of light  115  ( FIG. 37 ) when arthroscopic debridement template  15  is positioned at the “focal distance” from the bone, and to display a pair of lines of light  115 A,  115 B ( FIG. 38 ) when arthroscopic debridement template  15  is not positioned at the “focal distance” from the bone, whereby to provide the surgeon with a means for detecting bone protrusions. 
     And in another form of the present invention, and looking now at  FIG. 39 , arthroscopic debridement template  15  may comprise light sources  117  (e.g., light sources carried by flexible tip  52 ) which generate a plurality of beams of light  118 , wherein the beams of light  118  are configured so as to create an interference pattern  120  when they encounter a variation in the elevation of the bone (e.g., a bony protrusion), thereby providing the surgeon with a visual cue for guiding the debridement process. 
     In another form of the present invention, and looking now at  FIGS. 39A and 39B , arthroscopic debridement template  15  may comprise light sources  122  (e.g., light sources carried by flexible tip  52 ) which generate a plurality of beams of light  123 , wherein the beams of light  123  are configured so as to form discrete patterns  125  (e.g., lines, points, etc.) on the impinging bone surface which is to be debrided and diffuse areas of light  130  on the bone surrounding the impinging bone surface ( FIG. 39A ), and diffuse areas of light  130  across the entire bone surface after appropriate bone debridement ( FIG. 39B ). 
     In another embodiment of the present invention, and looking now at  FIGS. 40-43 , arthroscopic debridement template  15  may comprise markers  135  which are used to delineate the perimeter of a bony protrusion  10  which is to be debrided and/or to mark the depth to which the bony protrusion needs to be debrided. Markers  135  may be formed out of a biocompatible material such as metal (e.g., stainless steel), plastic, etc. Markers  135  may comprise a color, surface texture, shape and/or reflectivity which makes them easily identifiable under endoscopic visualization. Markers  135  may be made out of a material that is visible under X-ray imaging, such as a material having a higher radiodensity than bone (e.g., metal, plastic filled with BaSO 4 , etc.) or a material having a lower radiodensity than bone (e.g., plastic). Markers  135  may be made out of a material which is visible under other imaging means (e.g., MRI, ultrasound, etc.). By way of example but not limitation, and looking now at  FIG. 40 , a bony protrusion  10  is first identified by the surgeon (e.g., by way of one of the foregoing approaches, such as by using a mechanical arthroscopic debridement template  15  or another light-based arthroscopic debridement template  15 , etc.) and targeted for debridement. Next, one or more markers  135  are implanted into the bone (see, for example,  FIGS. 41 and 42 ), with the distal end of the marker  135  preferably being set at the depth desired for the bone surface after debridement in that region of the bony protrusion. Debridement can then proceed (see, for example,  FIG. 43 ) so as to remove the bony protrusion  10 , with the surgeon using the one or more markers  135  as a guide for indicating the location and/or depth of the bone which is to be removed. The surgeon may consult imaging means (e.g., X-ray, MRI, ultrasound, etc.) or visualization means (e.g., an endoscopic camera, etc.) as necessary during the procedure so as to confirm how much bone needs to be debrided in order to achieve the desired bone geometry. Marker(s)  135  are removed from the bone at or near the completion of the bone debridement procedure. 
     In another form of the present invention, one or more markers  135  are placed within the bone which is to be removed (i.e., within the bone protrusion). Markers  135  extend to a depth which is reflective of the amount of bone which is to be removed. The surgeon then uses the markers  135  as a guide for indicating the location and/or depth of the bone which is to be removed. In this form of the invention, the one or more markers  135  are removed from the patient prior to completion of the bone debridement procedure, such that the bone in which they resided can be fully debrided. 
     In one form of the present invention, a hole is first drilled into the bone and then the marker  135  is placed within the hole. In another form of the present invention, the marker  135  is driven directly into the bone (e.g., with a mallet) without forming a hole first. If desired, marker  135  may comprise surface features (e.g., screw threads, barbs, etc.) for enhancing engagement with the bone. 
     Of course, it should be appreciated that, if desired, marker(s)  135  may be utilized only for marking the perimeter of the bony protrusion which is to be removed, and the depth of bone debridement may be determined by other means (e.g., by use of one of the foregoing approaches). It should also be appreciated that marker(s)  135  may be utilized only for showing the depth of the bone debridement and the perimeter of the bone debridement may be indicated by other means. 
     Arthroscopic Debridement Templates Incorporating a Bone Cutting Element 
     In another form of the present invention, and looking now at  FIGS. 44-46 , arthroscopic debridement template  15  incorporates a bone cutting element  145 . More particularly, in this form of the invention, a bone cutting element  145  (e.g., a burr  146  turned by a torque coil  147 ) is housed within a sheath  150  which forms an arc  155  ( FIG. 44 ). Arc  155  of sheath  150  has a configuration which matches the desired bone geometry. Sheath  150  comprises a slot  160  through which a portion of bone cutting element  145  extends ( FIG. 45 ). To debride the bone, sheath  150  is placed on the target bone surface, then bone cutting element  145  (e.g., the burr) is moved along the arced sheath  150 , removing bone in the process ( FIG. 46 ). After bone cutting element  145  has completed its sweep along arced sheath  150 , thereby forming a complete cut in the bone, sheath  150  is repositioned on the target bone and the bone removal process is repeated. 
     Use of the Novel Arthroscopic Debridement Template for Applications Other than the Treatment of Cam-Type Femoroacetabular Impingement 
     It should be appreciated that the novel arthroscopic debridement template of the present invention may be used for applications other than the treatment of cam-type femoroacetabular impingement. 
     By way of example but not limitation, the novel arthroscopic debridement template of the present invention may be used to guide debridement of the acetabulum during treatment of pincer-type femoroacetabular impingement. 
     By way of further example but not limitation, the novel arthroscopic debridement template of the present invention may be used to guide debridement in joints other than the hip joint (e.g., to guide debridement of a surface of a humerus in order to prepare that surface for reattachment of a torn rotator cuff). 
     And by way of additional example but not limitation, the novel arthroscopic debridement template of the present invention may be used in non-arthroscopic procedures. 
     Modifications of the Preferred Embodiments 
     It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.
Apparatus for use in debriding a bone, said apparatus comprising: an arthroscopic debridement template comprising a body reconfigurable between (i) a first configuration having a first profile and comprising an arc matching the desired curvature of the bone after debridement, and (ii) a second configuration having a second profile, wherein said second profile is smaller than said first profile.