Patent Application
20070276396
The present invention relates to surgical instruments and, in particular to acetabular reamers.
An acetabular reamer having a reamer head is used in hip replacement surgery for re-forming the hip socket, or acetabulum, in preparation for implanting a prosthetic component, such as an acetabular cup or socket. To insure a proper fit of the prosthetic device, the deteriorated or diseased bone and cartilage needs to be cut or shaved away to healthy bone tissue so that the reamed acetabulum matches the contours of the prosthetic to be fitted.
In a typical hip replacement procedure, including an acetabular implant, a surgeon makes an incision in the hip area, displaces the existing hip joint, shapes the acetabulum with the reamer to receive a metallic or plastic prosthetic socket, inserts the prosthetic socket, replaces the ball of the femur with a prosthetic ball, and inserts the prosthetic ball into the prosthetic socket to complete the operation.
Typically, a reamer head is comprised of a continuous exterior surface that requires a large incision in the skin of the patient in order to place the reamer head adjacent the socket to be reamed. Such a reamer is shown in U.S. Pat. Nos. 5,658,290, 6,106,536 and 6,702,819. Unfortunately, the size of the incision, effects the time that is required for recovery of the operation with a larger size incision increasing the recovery time. In addition, a larger incision also makes the patient more susceptible to infection and increases the time frame that disease may be introduced into the body via the incision.
The present invention is directed to surgical instruments and implants. In one aspect of the present invention, a rotary surgical reamer assembly for moving bone and tissue from a bone joint include a dome and a body. The dome may include an exterior and an interior as well as a plurality of cutting sites disposed on the exterior and a plurality of apertures adjacent to the cutting sites. The body preferably includes a base, a ridge and at least one column connecting the base to the ridge. In one aspect of the present invention, the dome is attached to the ridge.
The assembly also preferably includes a circumferential ridge having an exterior and interior, a first edge, a second edge and an opening extending from the first edge to the second edge. The circumferential ring includes a plurality of cutting sites disposed on the exterior and a plurality of apertures adjacent to the cutting sites. The first edge of the circumferential ring is adjacent to the dome and the second edge of the circumferential ring is adjacent to the base of the body. Preferably, the exterior of the dome and the exterior of the circumferential ring form a substantially continuous wall.
In one aspect of the present invention, the dome and the circumferential ring are part-spherical and in combination form a substantially hemispherical shape. The dome may include a pole further comprising a polar axis passing through the pole. The exterior of the dome and the exterior of the circumferential ring are preferably substantially curvilinear relative to the polar axis.
In one aspect, the interior of the circumferential ring may include a first portion rectilinear relative to the polar axis such that when the circumferential ring is disposed on the body, the first portion engages the at least one column to thereby prevent rotation of the circumferential ring relative to the body.
The dome may be remote from the base of the body at a sufficient distance to permit the dome and the body to be placed through an incision concurrently without causing the cutting sites of the dome to engage soft tissue surrounding the incision, as compared to when the circumferential ring and the body are passed through the incision concurrently where the cutting sites would contact the soft tissue surrounding the incision.
In one aspect of the present invention, a method of removing bone and soft tissue from a bone joint may include providing a first portion of a surgical reamer. The first portion having a first cutting surface for removing bone and soft tissue. The method also comprising providing a second portion of a surgical reamer that also includes cutting surfaces for removing bone and soft tissue. After making an incision at a portion of a body to allow access to a bone joint, the first portion is placed through the incision and subsequently the second portion is place through the incision and into the vicinity of the bone joint. Once the first portion and second portion are placed within the vicinity of the bone joint, they are assembled together such that the first cutting surface and the second cutting surface form a substantially single cutting surface.
In one aspect of the present invention, a method of removing bone and soft tissue from a bone joint includes making an incision into the skin of a patient to allow access to a desired location. The incision has dimensions that permit a first portion and a second portion of a reamer to pass through the incision and into the desired location, without a cutting surface of the first portion or second portion coming into contact with the skin surrounding the incision. The method also includes assembling the first portion of the reamer to the second portion of the reamer wherein the resulting assembly has overall dimensions larger than the dimensions of the incision such that if the resulting assembly was passed through the incision, the cutting surface of either the first portion or the second portion would come in contact with the skin surrounding the incision.
In another aspect of the present invention, an orthopedic implant is provided having a core with an interior surface, an exterior surface, a first end and an apex. The core also includes an engagement element. The implant further includes a ring having an interior surface, an exterior surface, a first edge, a second edge and an opening extending from the first edge to the second edge. The ring also having an engagement element, which corresponds to the engagement element of the core. The opening of the ring being sized to receive the core such that the apex of the core may be passed through the opening until the first end of the core is adjacent to the first end of the ring. When the first end of the core is adjacent to the first end of the ring, the engagement element of the core may be mated with the engagement element of the ring to thereby lock the core to the ring. In one embodiment the orthopedic implant described above is an acetabular shell implant.
The present invention relates to a surgical reamer assembly in the form of an acetabular reamer assembly 10 as shown in
In one aspect of the present invention, the acetabular reamer assembly 10 preferably includes a first component having a body (not shown in
With reference to
The dome 12 preferably has an arcuate shape similar to a portion of a sphere that includes an apex of the sphere. Thus, as shown in
The dome 12 may be permanently or temporarily affixed to the main frame body 13. In one aspect of the present invention, the main frame body 13 includes a base 42, a ridge 44, remote from the base, and a plurality of connecting walls such as columns 46 extending from the base to the ridge. As shown in
Also as shown in
Another aspect of the present invention is ring 14, shown in
The ring 14 is situated about axis 30 and includes an opening 70 extending from the first edge 64 to the second circular edge 66. In one preferred embodiment, the opening 70 has a larger diameter adjacent to second circular edge 66 than its diameter adjacent to first circular edge 64.
As shown in
In a method of assembling the acetabular reamer assembly 10, the dome 12 is attached to the body 13, either integrally or modularly such as being held on by screws or a taper lock. The dome 12 may also be snap-fitted to the body 13 or each element may have a structure that corresponds to the other structure, which permits engagement between the two elements but does not permit rotation between the two. The ring 14 is placed over the dome 12 with the apex 21 of the dome being received within the opening 70 of the ring adjacent to second circular edge 66. The dome 12 and body 13 are continually translated through the opening 70 until the entire dome 12 extends outwardly past opening 70 adjacent first circular edge 64. With the dome 12 positioned atop of the first circular edge 64 of the ring 14, most of the body 13 is retained within opening 70 of ring 14. But the ridge 44 of the body 13 is adjacent the first circular edge 64 of the ring 14 and the second circular edge 66 of the ring 14 is adjacent base 42 of the body. Since the base 42 has a larger maximum diameter L′ than the length of the second diameter D′, the body 13 can not pass entirely though the opening 70. When assembled together, the dome 12 and ring 14 form a hemispherical body having a plurality of cutting sites 24 and 24A and a plurality of apertures 26 and 26A extending about their respective exterior surfaces, as shown in
In this configuration, the acetabular reamer assembly 10 is ready to be employed to ream out an acetabulum such that an acetabular shell may be positioned correctly during reconstructive surgery.
In order to prevent the ring 14 from being able to rotate about the body 13 when the acetabular reamer assembly is employed and more specifically when a force causes the ring 14 and the dome 12 to rotate about axis 30, an engaging mechanism may be provided as alluded to before. For instance, when assembling the ring 14 and the dome 12 together, the wall 71 of the ring 14 may be aligned with one of the columns 46 such that these two linear elements confront each other. Since the wall 71 and the column 46 are parallel or at least rectilinear to axis 30, and are proximate one another when the acetabular reamer assembly is assembled, once coupled together, they do not permit the ring 14 to rotate about the body 13 of the acetabular reamer assembly 10. Therefore, when the acetabular reamer assembly 10 is employed and a rotational force is applied to the body 13 via a surgical rotary hand piece, the ring 14, and dome 12 also rotate simultaneously. The engagement mechanism prevents unwanted motion of the ring 14 relative to the body 13.
In a method of use, the ring 14 and dome 12 are placed through an incision in the skin of a patient separately. After a surgeon determines an incision location on the patient, he next slices the skin to create the incision I, as shown in
Next, the dome 12 and body 13, which are already assembled together, are translated through the incision I. As with the ring 14, during introduction through the incision I the plane of the base of the dome/body are oriented sideways with a plane that is tangential to the apex 21 of the dome and the base 42 of the body being more parallel to the longitudinal direction of the incision I, than they are perpendicular. When translating the dome/body 12,13 through the incision the base 42 may be used to pry the walls of the incision I apart in order to enlarge the incision opening. Since the skin is generally flexible, this can be accomplished without any further tearing of the skin. Once again, because the dome/body 12, 13 only has cutting sites 24 along one portion of the combination component, i.e., dome 12 and body 13, and more specifically does not have cutting sites proximate the base 42 of the body, the size of the incision required to place the dome/body component in-situ is smaller than the size of an incision required to place a reamer having a continuous hemispherical cutting surface. This prevents the cutters from damaging the soft tissue.
Thus, since the acetabular reamer assembly 10 is positioned within the body in two stages, and specifically the cutting sites 24, 24A are separately inserted, the incision I may by smaller than required for conventional hemispherical reamers. This is because conventional hemispherical reamers include a continuous exterior surface with cutting sites. As the conventional reamer is inserted through an incision, the incision must be sufficiently wide to prevent the skin from being cut by the cutting sites. This is particularly problematic where a cross section of the reamer is at its largest diameter such as at a position nearest the base of the reamer. This is because as the reamer is inserted sideways, the incision must be long enough to receive the maximum diameter of the reamer but also wide enough to receive the width of the reamer. Thereby requiring a relatively large incision.
The present invention avoids this by dissecting the cutting sites 24, 24A into two distinct halves, the dome 12 and the ring 14. When oriented sideways, the ring 14 may have a maximum diameter that is equal to the diameter of a conventional hemispherical reamer also oriented sideways but the width of the ring is less. The combination of the dome 12 and body 13, when oriented sideways, has a width equal to the width of a conventional reamer but a maximum diameter that is less. And since the combination of the dome 12 and body 13 does not include cutting sites positioned proximate the end of the body that is remote from the dome, to insert the dome/body 12,13, the base 42 of the body maybe placed against the skin positioned adjacent a longitudinal side of the incision I. The body may then be used to pry open the flexible skin such that the dome/body 12,13 may be inserted therethrough. Because all of the cutting sites 24 are proximate only the ends of only one side of the incision, the likelihood that the cutting sites may contact the skin is reduced. Plus the requirement of greatly stretching the skin or having a larger incision is eliminated, as compared to an incision required for conventional hemispherical reamers. This configuration enables the dome/body 12, 13 to be received through an incision while minimizing the risk that a cutting site will tear the skin around an incision.
Once the dome/body 12, 13 are placed in-situ, they are rotated such that the apex 21 of the dome is aligned with the opening 70 of the ring 14. Also, if an engagement member is provided such as discussed above, it may be correctly aligned. For instance, a column 46 of the body may be aligned with the wall 71 of the ring 14. The dome/body 12, 13 is translated through the opening 70 until the entire dome 12 extends outwardly from the opening with the bottom ridge 23 of the dome positioned adjacent the first circular edge 64 of the ring. The wall 71 and column 46 may not only prevent unwanted movement between the ring 14 and body 12 but may also provide a key-way system, that only permits the components to be coupled together in a specific spatial relationship. In other words, the ring 14 and body 13 can not be coupled together unless the wall 71 and a column 46 are aligned.
Once the elements are assembled together and the handle 16 is coupled to the cross-bar system (the handle is preferably coupled to the body during insertion of the dome and the body), a rotary power device may be connected to the handle so as to provide rotational movement to the handle 16 and subsequently to the dome 12 and ring 14.
As the dome 12 and ring 14 rotate about axis 30, the cutting sites 24, 24A are brought into proximity of the bone and soft tissue to be reamed to thereby begin the process of creating a cavity in the bone.
In another aspect of the present invention, as already alluded to, the dome 12 may be coupled to the body 13 in a removable manner. Thus, as shown in
Although the present invention has been described in conjunction with an acetubular reamer assembly, the concept of the invention may also be adapted for other purposes. For instance, an acetabulum implant shell 110 may be dissected in half to form a core 112 and a ring 114, as shown in
In one method, after the acetabulum has been reamed, the ring 114 is inserted through an incision and placed adjacent the acetabulum. Next, the core 12 is inserted through the incision and subsequently through the opening 124 of the ring 114. The core 112 is translated entirely through the opening 124 until the circular edge 119 of the core 112 is adjacent the first circular edge 126 of the ring 114. In addition, the exterior surface 118 of the core 112 is positioned adjacent the acetabulum. Preferably, the interior surfaces, 116, 124 of the core 112 and ring 114 form a substantially smooth and continuous surface such that a prosthesis placed adjacent the interior surfaces can angulate and rotate smoothly against the surfaces.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
