Patent Publication Number: US-2023157706-A1

Title: Surgical reamer and method of reaming a bone

Description:
BACKGROUND 
     The present specification relates to a surgical reamer and to a method of reaming a bone using a surgical reamer. 
     An Extended Trochanteric Osteotomy is used during hip revision surgery to allow removal of well-fixed stems, bone cement or fractured prostheses. Once the intra-medullary intramedullary canal has been cleared, the trochanter is may be re-attached using a circlage and, in the case of a Wagner-type prosthesis, the intramedullary canal is reamed to allow a new implant to be inserted. 
     Revision implants can be in the region of 300 mm long and 25 mm in diameter, so it can be challenging to prepare the intramedullary canal without sacrificing the medial wall of the greater trochanter, which is not desirable. 
     Similar considerations apply to shoulder surgery. 
     SUMMARY 
     Aspects of the present disclosure are set out in the accompanying independent and dependent claims. Combinations of features from the dependent claims may be combined with features of the independent claims as appropriate and not merely as explicitly set out in the claims. 
     According to an aspect of the present disclosure, there is provided a surgical reamer comprising:
     a distal part comprising: 
   a proximal end coupleable to a surgical rotational driver for applying torque to the distal part;   a distal end;   a rotational axis extending between the proximal end of the distal part and the distal end of the distal part; and   a cutting surface located between the proximal end of the distal part and the distal end of the distal part; and   
   a proximal part comprising: 
   a proximal end coupleable to a surgical rotational driver for applying torque to the proximal part;   a distal end;   a rotational axis extending between the proximal end of the proximal part and the distal end of the proximal part;   a cutting surface located between the proximal end of the proximal part and the distal end of the proximal part; and   a cavity extending proximally from the distal end of the proximal part for receiving the proximal end of the distal part, wherein an inner surface of the cavity is shaped to allow the rotational axis of the proximal part to be tilted with respect to the rotational axis of the distal part during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity.   
   

     A surgical reamer according to embodiments of this disclosure can facilitate a two stage reaming process in which the distal part may be used to ream an interior surface of a bone (e.g. in an intramedullary canal) and then the proximal part can be mounted on the proximal end of the distal part for reaming at or near to an opening into the bone, within which the distal part is received. The mounting of the proximal part on the distal part allows tilting of the proximal part with respect to the distal part, whereby the features of the bone (e.g. the great trochanter) can be reamed laterally. In some embodiments, this can allow the reamed surface to match the shape of an implant to be installed within the bone. 
     The cavity may be shaped to allow the rotational axis of the proximal part to be tilted in a plurality of directions with respect to the rotational axis of the distal part during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity. This can add extra flexibility for reaming the bone according to the requirements of the surgical procedure by providing multiple degrees of freedom for the movement of the proximal part. 
     The cavity may be shaped to allow the rotational axis of the proximal part to be tilted for precession of the rotational axis of the proximal part about the rotational axis of the distal part during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity. This can add further flexibility for reaming the bone according to the requirements of the surgical procedure. 
     The cavity may be shaped to allow the rotational axis of the proximal part to be tilted with respect to the rotational axis of the distal part during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity by an angle θ in the range 0° ≤ θ ≤ 25°. 
     The cavity may be frustum shaped. A narrow end of the frustum shaped cavity may be located at the distal end of the proximal part. A wide end of the frustum shaped cavity may be located proximally with respect to the distal end of the proximal part. A cross section of the frustum shaped cavity in a plane perpendicular to the rotational axis of the proximal part may be substantially circular. These features can provide multiple degrees of freedom for the tilting of the proximal part, while also not inhibiting rotation of the proximal part with the proximal end of the distal part received within the cavity. 
     The proximal end of the distal part may be slideably insertable and removable from the cavity. This can also allow proximal/distal movement of the proximal part during reaming and tilting. 
     The proximal end of the distal part may have a connection feature for coupling to the surgical rotational driver. The cavity may have a depth equal to or greater than a length of the connection feature. This can allow the connection feature to be completely received within the cavity. The size (length) of the proximal part and the depth of the cavity can be chosen according to the areas of the bone that need to be reached by the cutting surface of the proximal part. 
     The distal end of the proximal part may have a chamfer to facilitate tilting of the proximal part with respect to the distal part. 
     A chamfer angle of the chamfer with respect to a plane perpendicular to the rotational axis of the proximal part may be substantially equal to or greater than a maximum value of tilt angle θ allowed by the shape of the cavity. 
     The cutting surface of the proximal part may extend between the distal end of the proximal part and a cutting shoulder located intermediate the distal end of the proximal part and the proximal end of the proximal part. The shoulder may aid in retrograde reaming of the greater trochanter. For instance, the shoulder may be shaped to match the profile of a part (e.g. shoulder) of an implant to be installed in the bone in accordance with a surgical procedure. 
     The proximal end of the proximal part may be narrower than the cutting surface at the cutting shoulder. 
     The cutting surface of the proximal part may be formed on a distal shaft portion of the proximal part. The distal shaft portion may be tapered to have a wider diameter at a distal end of the distal shaft portion than at a proximal end of the distal shaft portion. 
     A widest diameter of the cutting surface of the proximal part at the distal end of the proximal part may be substantially equal to a widest diameter of the cutting surface of the distal part. This can provide room for the coupling of the proximal end of the proximal part to a surgical rotational driver. 
     In some embodiments, the distal part may be elongate for reaming an inner surface of an intramedullary canal of a femur. The proximal part is elongate for reaming an inner surface of a greater trochanter of the femur. In some embodiments, the distal part may be elongate for reaming an inner surface of an intramedullary canal of a humerus. The proximal part is elongate for reaming an inner surface of a greater trochanter of the humerus. 
     According to another aspect of the present disclosure, there is provided a surgical kit comprising the surgical reamer of any of claims  1  to  14 . 
     According to another aspect of the present disclosure, there is provided a method of reaming a bone using a surgical reamer, the method comprising:
     reaming an inner surface of the bone using a distal part of the surgical reamer, wherein the distal part comprises: 
   a proximal end coupleable to a surgical rotational driver for applying torque to the distal part;   a distal end;   a rotational axis extending between the proximal end of the distal part and the distal end of the distal part; and   a cutting surface located between the proximal end of the distal part and the distal end of the distal part; and   
   reaming an inner surface of the bone using a proximal part of the surgical reamer, wherein the proximal part comprises: 
   a proximal end coupleable to a surgical rotational driver for applying torque to the proximal part;   a distal end;   a rotational axis extending between the proximal end of the proximal part and the distal end of the proximal part;   a cutting surface located between the proximal end of the proximal part and the distal end of the proximal part; and   a cavity extending proximally from the distal end of the proximal part for receiving the proximal end of the distal part, wherein an inner surface of the cavity is shaped to allow the rotational axis of the proximal part to be tilted with respect to the rotational axis of the distal part during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity,   
   wherein the reaming an inner surface of the bone using the proximal part of the surgical reamer includes tilting the rotational axis of the proximal part with respect to the rotational axis of the distal part during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity.   

     A method according to embodiments of this disclosure can provide a two stage reaming process in which the distal part may be used to ream an interior surface of a bone (e.g. in an intramedullary canal) and then the proximal part can be mounted on the proximal end of the distal part for reaming at or near to an opening into the bone, within which the distal part is received. The tilting of the proximal part with respect to the distal part can allow lateral reaming of features of the bone (e.g. the great trochanter). In some embodiments, this can allow the reamed surface to match the shape of an implant to be installed within the bone. 
     The distal part can remain substantially stationary within the bone during the reaming of the inner surface of the bone using the proximal part. 
     The method may include:
     coupling a surgical rotational driver to the proximal end of the distal part;   performing the reaming of the inner surface of the bone using a distal part;   decoupling the surgical rotational driver from the proximal end of the distal part;   coupling a surgical rotational driver to the proximal end of the proximal part;   receiving the proximal end of the distal part within the cavity while the distal part remains within the bone; and   performing the reaming of the inner surface of the bone using the proximal part.   

     The method may include tilting the rotational axis of the proximal part in a plurality of directions with respect to the rotational axis of the distal part during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity. 
     The method may include manually precessing the rotational axis of the proximal part about the rotational axis of the distal part during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity. 
     The method may include reaming the bone using a cutting shoulder of the cutting surface of the proximal part to substantially match a shape of a shoulder part of an implant to be installed in the bone. 
     The method may include tilting the rotational axis of the proximal part with respect to the rotational axis of the distal part by during rotation of the proximal part about the rotational axis of the proximal part with the proximal end of the distal part received within said cavity an angle θ in the range 0° ≤ θ ≤ 25°. 
     The method may include slideably inserting/removing the proximal end of the distal part into/from the cavity. 
     In some embodiments, the bone may be a femur. Performing the reaming of the inner surface of the bone using the distal part may comprise reaming an inner surface of an intramedullary canal of the femur. Performing the reaming of the inner surface of the bone using the proximal part may comprise reaming an inner surface of a greater trochanter of the femur. 
     In some embodiments, the bone may be a humerus. Performing the reaming of the inner surface of the bone using the distal part may comprise reaming an inner surface of an intramedullary canal of the humerus. Performing the reaming of the inner surface of the bone using the proximal part may comprise reaming an inner surface of a greater trochanter of the humerus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of this disclosure will be described hereinafter, by way of example only, with reference to the accompanying drawings in which like reference signs relate to like elements and in which: 
         FIG.  1    shows an implant; 
         FIG.  2    shows a distal part of a surgical reamer according to an embodiment of this disclosure; 
         FIG.  3    shows a cross section of the distal part of the surgical reamer of  FIG.  2   ; 
         FIG.  4    shows a proximal part of a surgical reamer according to an embodiment of this disclosure; 
         FIG.  5    shows a cross section of the proximal part of the surgical reamer of  FIG.  2   ; 
         FIG.  6    shows a cross section of an assembled surgical reamer including the distal part of  FIGS.  2 - 3    and the proximal part of  FIGS.  4 - 5    according to an embodiment of this disclosure; and 
         FIG.  7    illustrates a method of reaming a bone using the surgical reamer of  FIGS.  2 - 6    according to an embodiment of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of this disclosure are described in the following with reference to the accompanying drawings. 
     The embodiments described below relate to a surgical reamer and method for use in hip surgery. It is envisaged however that a surgical reamer and method according to embodiments of this disclosure may be employed in shoulder surgery. 
       FIG.  1    shows an implant  20 . The implant  20  is for use in a hip replacement procedure. The implant  20  includes an elongate stem  26 , which may taper to a distal tip  28 . The stem  26  is shaped to be received within the intramedullary canal of a femur, for example as part of hip revision surgery. The length of the stem  26  is denoted in  FIG.  1    as “F”. The implant  20  also includes a neck portion  22 , which extends at an angle from a proximal end of the stem  26 . The implant  20  may also include a shoulder  24  located adjacent a base of the neck portion  22 . A proximal end of the neck portion  22  is configured for attachment to a head portion, for insertion in the acetabulum of the patient. The implant  20  may be a trial implant for use the hip revision surgery or may comprise the final implant to be installed in the patient. As noted above, it is envisaged that an embodiments of this disclosure may be employed in shoulder surgery involving an analogous kind of implant. 
     In order to prepare the femur of the patient for installation of the implant  20 , the intramedullary canal must be accessed, and then bone removed from the inside of the canal so that that a suitable cavity is available to receive the stem  26 . During hip revision surgery, in which a previous implant is to be replaced with a new stem, a procedure known as Extended Trochanteric Osteotomy may be employed. Extended Trochanteric Osteotomy involves removal of the stem of the previous implant from the intramedullary canal as well as any bone cement. Once the intra-medullary intramedullary canal has been cleared, the trochanter of the femur may be re-attached using a circlage and, in the case of a Wagner-type prosthesis, the intramedullary canal is reamed to remove any further bone that is required to make a suitable cavity for receiving the new implant. Similar considerations may apply in the case of shoulder surgery. Embodiments of this disclosure relate to a surgical reamer and method for performing this task. 
       FIGS.  2  to  6    show various views of a surgical reamer according to an embodiment of this disclosure. In particular,  FIG.  2    shows a distal part  10  of the surgical reamer,  FIG.  3    shows a cross section of the distal part  10 ,  FIG.  4    shows a proximal part  30  of a surgical reamer,  FIG.  5    shows a cross section of the proximal part  30  and  FIG.  6    shows a cross section of an assembled surgical reamer including the distal part  10  and the proximal part  30  coupled together.  FIG.  7    illustrates a method of reaming a femur using the surgical reamer of  FIGS.  2 - 6    according to an embodiment of this disclosure. 
     The distal part  10  has a proximal end  2 . The proximal end  2  is couplable to a surgical rotational driver for applying torque to the distal part  10 . The proximal end  2  in this embodiment comprises a substantially cylindrical shaft which may be inserted into the surgical rotational driver for coupling the distal part  10  to the driver. It is envisaged that the proximal end  2  of the distal part  10  may include any suitable connection features for implementing the coupling of the distal part  10  to the driver. As will be described in more detail below, the proximal end  2  may also be used to be couple the distal part  10  to a proximal part  30  of the surgical reamer. 
     In use, the application of torque to the distal part  10  by the surgical rotational driver may cause rotation of the distal part  10  to allow the distal part  10  to act a drill/reamer for removing bone cement and/or bone from the femur (or humerus in the case of shoulder surgery) as part of an Extended Trochanteric Osteotomy. 
     The distal part  10  also has a distal end  4 . In this embodiment, a tapered shaft  6  extends between the proximal end  2  (e.g. from a distal end of the substantially cylindrical shaft forming the proximal end  2 , as shown in  FIGS.  2  and  3   ) and the distal end  4 , along a rotational axis  14  of the distal part  10 . The tapered shaft  6  tapers inwards toward the distal end  4 , such that the distal end forms a tip of the distal part  10 . The tapered shaft  6  may have a substantially circular cross section in a plane perpendicular to the rotational axis  14  of the distal part  10 . 
     The distal part  10  further includes a cutting surface  12 , which is located between the proximal end  2  and the distal end  4  of the distal part  10 . In this embodiment, the cutting surface  12  comprises an outer surface of the tapered shaft  6 . The surface of the tapered shaft may include any suitable surface features for implementing the cutting surface  12 . In this embodiment, the cutting surface  12  comprises a plurality of substantially helical flutes  13 , which extend from a proximal shoulder  8  of the tapered shaft  6  toward the distal end  4 . 
       FIGS.  2  and  3    denote a number of dimensions associated with the distal part  10  in this embodiment. In particular:
     ϕB 1  denotes a diameter of the shoulder  8  located at the proximal end of the tapered shaft  6  (i.e. the diameter of the tapered shaft  6  at its widest part);   E denotes a length of the tapered shaft  6  between the shoulder  8  and the distal end  4 ; and   ϕB 2  denotes a diameter of the substantially cylindrical shaft forming the proximal end  2  of the distal part  10  in this embodiment.   

     Turning now to  FIGS.  4  and  5   , the proximal part  30  of the surgical reamer has a proximal end  32  and a distal end  34 . As with the proximal end  2  of the distal part, the proximal end  32  of the proximal part  30  is couplable to a surgical rotational driver for applying torque to the proximal part  30 . The proximal end  32  in this embodiment comprises a substantially cylindrical shaft which may be inserted into the surgical rotational driver for coupling the distal part  10  to the driver. It is envisaged that the proximal end  32  of the proximal part  30  may include any suitable connection features for implementing the coupling of the proximal part  30  to the driver. For instance, in this embodiment, a flange is located at a proximal end of the substantially cylindrical shaft forming the proximal end  32 . 
     In use, the application of torque to the proximal part  30  by the surgical rotational driver may cause rotation of the proximal part  30  to allow the proximal part  30  to act a reamer for removing bone cement and/or bone from the femur (or humerus in the case of shoulder surgery) as part of an Extended Trochanteric Osteotomy. This will be described in more detail below. 
     The proximal part  30  has a rotational axis  44 , which extends between the proximal end  32  and the distal end  34  of the proximal part  30 . In this embodiment, a shaft  36 / 46  extends between the proximal end  32  (e.g. from a distal end of the substantially cylindrical shaft forming the proximal end  32 , as shown in  FIGS.  4  and  5   ) and the distal end  34 , along the rotational axis  44 . The shaft  36 / 46  may have a substantially circular cross section in a plane perpendicular to the rotational axis  44  of the proximal part  30 . The shaft  36 / 46  in this embodiment includes a distal shaft portion  36  and a proximal shaft portion  46 . In some embodiments, the proximal shaft portion  46  may be omitted. The proximal shaft portion  46  may have a substantially smooth outer surface and may be used to provide a working distance between the proximal end  32 , which is attached to the driver, and the cutting surface  42  to be described below. 
     The proximal part  30  further includes a cutting surface  42 , which is located between the proximal end  32  and the distal end  34  of the proximal part  30 . In this embodiment, the cutting surface  12  is located on an outer surface of the distal shaft portion  36 . The surface of the distal shaft portion  36  may include any suitable surface features for implementing the cutting surface  42 . In this embodiment, the cutting surface  42  comprises a plurality of substantially helical flutes  33 , which extend form a proximal cutting shoulder  38  of the distal shaft portion  36  toward the distal end  34 . The proximal shoulder  38  in this embodiment is located at the interface between the proximal shaft portion  46  and the distal shaft portion  36 , but may be located adjacent the proximal end  32  in embodiments in which the proximal shaft portion  46  is omitted. The features of the proximal part  30  located proximally with respect to the proximal cutting shoulder  38 , including the proximal end and the proximal shaft portion  46  (if any) may all be narrower than the cutting surface  42  at the proximal cutting shoulder  38 , so that they do not interfere with the use of the proximal cutting shoulder  38 . 
     The proximal part  30  further includes a cavity  50 . The cavity  50  extends proximally from the distal end  34  of the proximal part  30 . The cavity is shaped and sized to receive the proximal end  2  of the distal part  10 . In particular, an inner surface of the cavity  50  is shaped to allow the rotational axis  44  of the proximal part  30  to be tilted with respect to the rotational axis  14  of the distal part  10  during rotation of the proximal part  30  about the rotational axis  44  of the proximal part  30  with the proximal end  2  of the distal part  10  received within the cavity  50 . The depth of the cavity  50  may be chosen such that the proximal end  2  of the distal part  10  may be completely received within the cavity  50 . 
     In this embodiment, the cavity  50  is frustum shaped, although it will be appreciated that this is not essential and that other shapes may allow the aforementioned tilting of the proximal part  30  relative to the distal part  10 . A narrow end of the frustum shaped cavity  50  is located at the distal end  34  of the proximal part  30 , and a wide end of the frustum shaped cavity  50  is located proximally with respect to the distal end  34  of the proximal part  30 . The frustum shaped cavity  50  in this embodiment has a substantially circular cross section in the plane perpendicular to the rotational axis  44 . As will be described in more detail below, a cavity  50  having this internal shape can allow the proximal part  30  to be tilted and then processed around the rotational axis  14  of the distal part  10  while the proximal end  2  of the distal part  10  is received within the cavity  50 . The taper angle of the frustum shaped cavity  50  may be chosen to determine a maximum tilt angle of the proximal part  30 . 
       FIGS.  4  and  5    denote a number of dimensions and angles associated with the dis proximal part  30  in this embodiment. In particular:
     ϕB 3  denotes a diameter of the distal shaft portion  36 ; 
   In some embodiments, the diameter of the distal shaft portion  36  of the proximal part  30  may be chosen to approximate or match the diameter of the tapered shaft  6  at its widest part (i.e. ϕB 3  ≈ ϕB 1 );   
   C denotes a length of the distal shaft portion  36  between the proximal shoulder  38  of the distal shaft portion  36  and the distal end  34 ;   ϕB 4  denotes a diameter of the opening of the cavity  50 , which is located at the distal end  34  of the proximal part  30  - in some embodiments this diameter may be chosen to match the diameter of the substantially cylindrical shaft forming the proximal end  2  of the distal part  10 , plus a tolerance, i.e. ϕB 4  ≈ ϕB 2 ; and   G denotes the taper angle between the internal wall  52  of the cavity  50  and the rotational axis  44  - note that in this embodiment, the tilt angle θ of the proximal part  30 , at which the proximal end  2  abuts the side wall  52  of the cavity  50 , is equal to G at maximum tilt (see  FIG.  6   ); in some embodiments, 0° ≤ G ≤ 25° (and hence the maximum value of tilt angle θ is also in the range 0° ≤ θ ≤ 25°).   

     It is envisaged that in some embodiments, the distal shaft portion  36  may be tapered. In particular, the distal shaft portion  36  may tapered such that it is narrower proximally and wider distally, forming a reverse cone configuration. The combination of the taper angle of the distal shaft portion  36  and the value of G in such embodiments would allow a tapered cavity to be reamed while providing substantial clearance with the trochanter. By way of example only, a 2.5 degree tapered cavity could be reamed by using angle G of 22.5° and a “reverse” taper angle of the distal shaft portion  36  of 20°, giving substantial clearance with the trochanter at the same time. 
     Turning now to  FIG.  6   , the coupling between the distal part  10  and the proximal part  30  of the surgical reamer will be described in more detail. 
     As can be seen in  FIG.  6   , the proximal part  30  may be coupled to the distal part  10  by inserting the proximal end  2  of the distal part  10  into the cavity  50  of the proximal part  30 . The proximal end  2  may be slideably inserted into the cavity  50 . With the proximal end  2  received within the cavity  50 , the surgeon may manipulate the proximal part to change the tilt angle θ between the proximal part  30  and the distal part  10  ( FIG.  6    shows the proximal part  30  tilted by the maximum tilt angle θ =G, such that the proximal end  2  abuts the internal side wall  52  of the cavity  50 ) and to change the distance D between the distal end  34  of the proximal part  30  and the proximal shoulder  8  of the distal part  10 . Note that the vertical “height” of the cutting surface  42  of the distal shaft portion  36  along the rotational axis  14  is given by C.cos(θ) ≈ C for small tilt angle θ. 
     These manipulations may be performed while torque is being applied to the proximal part  30  to rotate the proximal part relative to the distal part  10 . This can allow the surgeon to use the cutting surface  42  of the proximal part  30  to perform lateral reaming of the femur (or humerus in the case of shoulder surgery) while using the coupling between the proximal end  2  of the distal part  10  and the cavity  50  of the proximal part  30  as a guide. Note that in use there is substantially no torque transfer between the proximal part  30  and the distal  10  and the distal part  10  generally remains stationary during rotation of the proximal part  30  in accordance with embodiments of this disclosure. The provision of a substantially cylindrical proximal end  2  and a frustum shaped cavity  50  can provide a smooth coupling between the distal part  10  and the proximal part  30  to aid against inadvertent torque transfer in practice. 
     Returning briefly to  FIG.  1   , in some embodiments, the combined lengths of the distal shaft portion  36  and the tapered shaft  6 , plus a typical value for the distance D during the procedure may be chosen to approximate or match the length F of the stem  26  (i.e. E+C+D≈ F). 
     Turning to  FIG.  7   , a method of reaming a femur  60  using the surgical reamer of  FIGS.  2 - 6    according to an embodiment of this disclosure will now be described. As noted above, it is envisaged that the method may also apply to shoulder surgery in which the humerus is to be reamed. 
     In an initial step, the distal part  10  may be attached to a surgical rotational driver and then used to perform initial reaming of the femur  60  (or humerus in the case of shoulder surgery). This reaming may include the removal of bone inside the intramedullary canal  70  of the femur  60  (or humerus in the case of shoulder surgery), which generally involves inserting the distal part  10  into the intramedullary canal  60  as shown in  FIG.  7   , and manipulating the distal part  10  while torque is applied to the distal part  10 . In some embodiments, the taper angle of the tapered shaft  6  may approximate or match the taper angle of the elongate stem  26  of an implant  20  of the kind shown in  FIG.  1   , to aid in shaping an internal taper of the intramedullary canal  70  to receive the implant  20 . Once this reaming step has been performed, the surgical rotational driver may be disconnected from the distal part  10 , while leaving the distal part inside the intramedullary canal  60 . 
     In a next step, the proximal part  30  may be coupled to a surgical rotational driver (which may or may not be same driver as that used to rotate the distal part  10  in the initial reaming step described above) and coupled to the distal part  10  by feeding the proximal part into the intramedullary canal so that the proximal end  2  is received within the cavity  50 . Torque may then be applied to the proximal part  30  to ream bone from the femur  60  (or humerus in the case of shoulder surgery) while the surgeon manipulates the proximal part  30 . These manipulations may include or more of:
     moving the proximal part along a direction parallel to the rotational axis  14  of the distal part  10 , to change the vertical position of the proximal part  30  within the femur  60  (or humerus in the case of shoulder surgery) as represented in  FIG.  7    by the arrow labelled H;   tilting the proximal part  30  in one or more directions, so that the rotational axis  44  of the proximal part  30  tilts with respect to the rotational axis  14  of the distal part  10 ; and   processing the proximal part  30  around the rotational axis  14  of the distal part  10  as indicated by the arrow labelled K in  FIG.  7    (the arrow labelled J in  FIG.  7    represents the rotation of the proximal part  30  around its own rotational axis  44 )   

     In some embodiments, the parts of the cutting surface  36  located near the shoulder  38  of the proximal part of the proximal part  30  may be used for reaming away a surface  66  of the greater trochanter  62  of the femur  60  (or humerus in the case of shoulder surgery) as illustrated in  FIG.  7   . The shoulder  38  may aid in retrograde reaming of the greater trochanter. For instance, the shoulder  36  may have a profile which approximates or matches a profile of the shoulder  24  of an implant  20  of the kind shown in  FIG.  1   , to aid in preparing the surface of the bone to receive the implant  20 . The inner surface (e.g. sidewall  52  of the cavity  50  may be shaped so that the maximum tilt angle of the proximal part  30  relative to the distal part  10  prohibits over-reaming of, for instance, the greater trochanter  62  while performing this step. 
     Once the reaming has been completed, the proximal part  30  may be decoupled from the distal part  10  by withdrawing the proximal part from the femur  60  (or humerus in the case of shoulder surgery). The distal part  10  may then also be removed from the femur  60  (or humerus in the case of shoulder surgery) and the procedure may proceed to the insertion of the implant within the femur  60  (or humerus in the case of shoulder surgery). 
     Returning to  FIG.  5   , in some embodiments, the distal end  34  of the proximal part  30  may be provided with a chamfered portion  35 . This chamfered portion  35  may taper outwardly such that the diameter of the distal shaft portion  36  increases from the opening of the cavity to the diameter ϕB 3  as one moves proximally along the distal shaft portion  36  from the distal end  34 . The chamfered portion  35  can aid in the tilting of the proximal part  30  with respect to the distal part  10 . The taper angle of the chamfered portion  35  (measured between the surface of the chamfered portion  35  and the plane perpendicular to the rotational axis  44 ) may, for instance, be substantially equal to, or greater than, the angle G, to allow the maximum tilt of the proximal part  30  to be reached, without the surface of the chamfered portion  35  of the distal end  34  contacting the proximal shoulder  8  of the distal part  10 . This can prevent inadvertent movement of the proximal part  30  along the rotational axis  14  of the distal part  10  owing to the riding of the distal end  34  of the proximal part  30  on the proximal shoulder  8  of the distal part  10  while the proximal part  30  is being tilted. 
     A surgical reamer of the kind described herein may be included in a surgical kit. 
     Accordingly, there has been described a surgical reamer and a method of reaming a bone using a surgical reamer. The reamer has a distal part comprising a proximal end coupleable to a surgical rotational driver; a distal end; a rotational axis extending between the proximal end and the distal end; and a cutting surface located between the proximal end and the distal end. The reamer also has a proximal part comprising a proximal end coupleable to a surgical rotational driver; a distal end; a rotational axis extending between the proximal end and the distal end; a cutting surface located between the proximal end and the distal end; and a cavity extending proximally from the distal end for receiving the proximal end of the distal part. An inner surface of the cavity is shaped to allow the proximal part to be tilted with respect to the distal part during rotation of the proximal part. 
     Although particular embodiments of this disclosure have been described, it will be appreciated that many modifications/additions and/or substitutions may be made within the scope of the claims.