[0001] Implanted prostheses need to be removed in revision surgeries. For example, there may be a need for a prosthesis to be revised due to its failure.

Removal of the prosthesis can be complicated by substantial ingrowth of surrounding bone tissue into the prosthesis during the time that the prosthesis is implanted. In some instances, the prosthesis may need to be cut out of the bone prior to removal in order to prevent extensive damage to the patient during removal. In the case of a hip prosthesis, it is often necessary to cut around the perimeter of the prosthesis sleeve in order to extract the implant. U.S. Patent No. 4,406,023, entitled "Stemmed Femoral Component for the Human Hip," describes an example of a proximal hip prosthesis and suggests using an osteotome (a chisel-like knife used to cut bone) for removal. The same concept can be applied to extracting a modular sleeve component where a flat or curved osteotome could be used to make multiple cuts all around the edge of the sleeve for extraction.

[0002] Extraction has also been accomplished by drilling into the fractured proximal end of an embedded prosthesis tip and locking into that drilled hole with some form of extractor device to enable withdrawing of the prosthesis tip as, for example, illustrated in U.S. Patent No. 4,399,813, entitled "Apparatus and Method For Removing a Prosthesis Embedded in Skeletal Bone." Such techniques have been used as an alternative to an osteotome to avoid cutting the bone while driving out the prosthesis.

[0003] U.S. Patent No. 4,686,971, entitled "Method and Apparatus for Extraction of Prostheses," provides another extraction technique. It describes an apparatus that has a housing, one end of which is provided with a bearing surface which is adapted to rest in a load-bearing relationship with the proximal end of a bone. A threaded nut axially shifts a threaded internal shaft. Rotation of the nut causes a force to be applied to the prosthesis generally along the direction of elongation thereof. This force is applied in a controlled, continuous manner to slowly break the bonds between the component and the bone.

[0004] Another method of extraction is outlined in U.S. Patent No. 6,565,575, entitled "Method and Apparatus for Removing an Acetabular Cup." It describes a device seated within an acetabular prosthesis and a blade positioned such that it moves along a path around the outer hemispherical surface of the acetabular cup component separating the prosthesis and surrounding bone.

[0005] Certain problems may arise when the foregoing technologies are used to remove implants. In some instances, particularly where tissue ingrowth is substantial, the cuts needed to free a femoral implant, for example, from the surrounding tissue can be imprecise. In such instances, the consequences can be detrimental to the patient. For example, when making a cut using one or more of the foregoing techniques, the blade may be prone to slip or extend beyond the perimeter of the implant being cut, thereby resulting in extraction of additional and more than desired bone from the patient. However, when attempting to avoid such unnecessary bone cutting, physicians often find it difficult to cut around the implant without shaving the implant itself. In that instance, metal or polymer shavings from the implant or from the device, arising from the contact between the device and the implant, can be lodged within the patient and lead to infection, inflammation and other ill effects. Improved methods and devices are needed, therefore, to extract orthopedic implants such as femoral sleeves and femoral stems from a patient's femur.

Summary

[0006] System, methods and devices are disclosed for removing a prosthesis by attaching a device to the prosthesis guiding a blade to cut the prosthesis away from bone in which the prosthesis is implanted. Certain methods involve attaching a device to a prosthesis within a surgical site. In this approach, the device has a first portion that attaches to the prosthesis, for example using threads, to anchor the device to the prosthesis and fix the orientation of a central axis of the device relative to the prosthesis. Anchoring the device helps stabilize the device to provide more accurate cuts around the prosthesis. In certain implementations, the device anchors to the prosthesis by a prosthesis anchor that has a central (e.g., longitudinal) axis, about which other components of the device can rotate to cut tissue away from the prosthesis. In certain embodiments, a longitudinal axis of the anchor is aligned substantially parallel with a longitudinal axis of the prosthesis.

[0007] In certain implementations, a device for extracting an implanted prosthesis includes a prosthesis anchor that has a first end configured to anchor to an implanted prosthesis, and a shaft. The device includes a housing operably engaged to a drive mechanism and configured to rotate about the shaft, and a blade is disposed at a distal end of the housing. In some embodiments, the housing is coupled to the shaft and configured to rotate about a longitudinal axis of the shaft, and the shaft and housing may be coupled either directly or via one or more intermediate components. The drive mechanism engaged to the housing actuates rotation of the housing.

[0008] One or more attachment mechanisms are used to couple the housing and the shaft of the device. In certain implementations, the housing includes a through hole that receives the shaft. In certain implementations, the housing includes a socket that receives a ball on the shaft. The housing may be attached by coupling to a coupling portion that mates with a tapered neck of a femoral prosthesis. The shaft may include a distal threaded portion for attachment to a prosthesis, and a proximal device head.

[0009] The blade disposed at the distal end of the housing is rotated to cut an arc through surrounding tissues. In certain implementations, the blade itself is arced. In some embodiments, the blade includes a distal tip having a blunt portion and a sharp portion. The blunt portion is disposed adjacent to the sharp portion and spaces the sharp portion away from direct contact with a prosthesis. In certain implementations, a proximal end of the blade is adjustably positionable within a component of the housing, and the proximal end may be adjustable positionable in a direction substantially perpendicular to a longitudinal axis of the shaft.

[0010] The extracting device can be used to remove a full femoral stem, a stem with a modular sleeve attachment, or just an implanted sleeve. In certain embodiments, the device includes a stopper on the distal end of the shaft. In certain embodiments, the device includes a tapered plug disposed on the distal end of the shaft, and the tapered plug may engage an inner surface of a femoral sleeve.

[0011] In certain implementations, a method of separating an orthopedic implant from surrounding tissue includes anchoring a distal end of a shaft to a prosthesis femoral stem such that a longitudinal axis of the shaft is aligned substantially parallel to a longitudinal axis of the prosthesis stem, coupling a blade to the shaft, and rotating the blade in an arc about a perimeter of the stem to cut tissue located substantially along the arc. The shaft may be anchored to a tapered neck of the prosthesis femoral stem or may be anchored to a location on the stem distal to a tapered neck of the stem, and the shaft may be anchored to a location on the longitudinal axis of the femoral stem. In certain embodiments, the method includes extending a distal component of the shaft to fit below a sleeve of the implant. In certain embodiments, the method includes attaching the shaft to a location on the femoral stem that is parallel to but offset from the central axis of the femoral stem, and coupling a housing to the shaft.

[0012] In certain implementations, a method of operating an extraction device includes positioning a distal end of the device at a proximal end of a prosthesis stem, actuating an attachment mechanism that anchors the device to the prosthesis stem, and actuating a drive mechanism that rotates a blade in an arc about a perimeter of the stem. Actuating the attachment mechanism may include turning a knob at a proximal end of the device that causes a threaded shaft at the distal end of the device to rotate, and actuating the drive mechanism may include rotating a handle of the device that rotates a sleeve of the device coupled to the blade. The device may be positioned such that a longitudinal axis of a shaft of the device is aligned substantially parallel to a longitudinal axis of the prosthesis stem, or the device may be positioned such that a longitudinal axis of the shaft of the device is parallel to but offset from the central axis of the prosthesis stem. In certain embodiments, the method includes extending a distal component of the device to fit below a sleeve coupled with the prosthesis stem. In some embodiments, the device includes a shaft and the method includes coupling a housing to the shaft.

[0013] In certain embodiments, at least one or more interchangeable, adjustable and/or fixed cutting blade may be attached and/or adjusted with respect to an attaching portion. Such blades may be selected and/or adjusted based upon the size of the implant to be removed. In use, such an attachment portion can be seated in close proximity to the prosthesis such that the end of the cutting blade is disposed closely adjacent to the rim of the prosthesis. The cutting blade may rotate with respect to one or more axes around a central portion of the instrument to cut the implant away from the bone for extraction of the prosthesis.

Brief Description of the Drawings

[0014] The foregoing and other objects and advantages will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:

[0015] Figures 1 A-C illustrate a device for cutting a prosthesis away from one or more bones or other tissue;

[0016] Figure 2 illustrates the attachment of the device of Figures 1A-C to the prosthesis;

[0017] Figure 3 illustrates an embodiment in which a device is attached to a sleeve to remove the sleeve from its implanted location;

[0018] Figures 4 A-C illustrate attachments of a device to a prosthesis;

[0019] Figures 5A and 5B illustrate a cutting blade;

[0020] Figures 6A and 6B illustrate a cutting blade that includes shearing teeth;

[0021] Figures 7 A and 7B illustrate a cutting blade having a rectangular configuration;

[0022] Figures 8A-C illustrate a spout that can be cut away from an implanted position using a cutting device embodiment;

[0023] Figures 9A and 9B illustrate a process for removing a sleeve portion of an implant following removal of a stem portion of the implant;

[0024] Figures 10 illustrates a process for adjusting a blade;

[0025] Figure 11 illustrates a blade having a blunt tip; and

[0026] Figures 12 A-C illustrate a blade having a portion that contacts the outer surface of a prosthesis and an adjacent cutting portion. Detailed Description

[0027] To provide an overall understanding of the systems, devices, and methods described herein, certain illustrative embodiments will be described. Although the embodiments and features described herein are specifically described for use in connection with removal of implanted femoral stem and sleeve systems, it will be understood that the components, connection mechanisms, adjustable systems, removal methods, devices, and other features outlined below may be combined with one another in any suitable manner and may be adapted and applied to other medical devices and implants to be used in other removal or revision procedures.

[0028] In certain embodiments, a device has a portion for fixing the device's orientation with respect to a prosthesis and another portion that can be rotated and/or moved in relation to the first portion to cause a blade to cut the prosthesis away from one or more bones or other tissue to extract the prosthesis from an implanted location in a patient's body. In particular, the device includes a first portion configured to attach to a prosthesis to orient the device relative to the prosthesis and a second portion engaging the first portion in a fixed orientation relative to the prosthesis. The device is configured such that the second portion engages the first portion in a way that allows the second portion to rotate with respect to the first portion. Such rotation of the second portion moves a blade in a path adjacent to one or more surfaces of the prosthesis.

[0029] Figures 1A-C illustrate a device 1 for cutting a prosthesis 10 away from one or more bones or other tissue (not shown). The prosthesis 10 includes a stem 14, such as a femoral stem, and a sleeve 12 that houses the stem and is inserted into the patient's femur during hip reconstruction. For example, a stem and sleeve system known as the Modular Distal Fixation system, as manufactured by Smith & Nephew, Inc., may be used. The device 1 has an inner shaft 2, which anchors to the prosthesis. The inner shaft 2 is coupled with a housing that includes an outer sleeve 3, a handle 4, and a blade 5. Rotation of the handle 4 causes the outer sleeve 3 and attached blade 5 to rotate with respect to the central axis 6 of the device 1 (shown in Figure IB). The blade 5 extends from an outer circumferential surface at the distal end of the housing. In other embodiments, multiple blades are used.

[0030] When the housing rotates, the blade 5 moves along one or more paths adjacent to, although not necessarily touching, one or more exterior surfaces of the prosthesis 10. Such movement can be used to detach the prosthesis 10 from implanted bone or otherwise help free the prosthesis 10 from its implanted position, for example for removal during revision surgery.

[0031] Figure 2 depicts the attachment of the device 1 of Figures 1A-C to the prosthesis 10. As shown in Figure 2, the device 1 includes an impacting surface 7 for driving the device 1 and, therefore, blade 5 downward in the direction 8 parallel with the central axis 6 (shown in Figure IB). Driving the blade 5 in this manner can be used to detach the prosthesis 10 from implanted bone or otherwise help free the prosthesis 10 from its implanted position.

[0032] The inner shaft 2 of the device attaches to the prosthesis 10 to fix the orientation of the device 1 with respect to the prosthesis 10. More particularly, the shaft 2 has a distal end 13 anchored to the prosthesis to stabilize the device 1 with respect to the prosthesis. The inner shaft 2 is anchored to the prosthesis 10 by threads on the distal end 13, which engage a complementary threaded receptacle 11 bored into the prosthesis 10. The threaded receptacle 11 may be present in the prosthesis 10 when the prosthesis is implanted, for example as a driver hole used during implantation, or may be bored into a solid portion of the prosthesis 10 during a revision surgery. The threads and receptacle are engaged and tightened by rotating the knob 9 at the proximal end of device 1 , which rotates the inner shaft 2. When anchored to the device 1, the shaft 2 forms a stable axis about which the cutting blade 5 can rotate to more precisely sever the tissue abutting or adjacent to the prosthesis.

[0033] In certain implementations, the device 1 can be used in a hip revision surgery. In particular, the distal end 13 of the shaft 2 can be anchored to the prosthesis femoral stem, such that a longitudinal axis 6 of the shaft is substantially parallel to and aligned with a longitudinal axis of the prosthesis stem. By aligning the axes of the stem and the shaft in parallel, the blade 5 (and the housing with the outer sleeve 3) can be coupled to the shaft and rotated so that the blade moves in an arc about a perimeter of the implant to cut away tissue substantially along the arc. In certain implementations, the shaft 2 is anchored to a proximal head of a prosthesis femoral stem. In other implementations, the shaft is anchored to a location on a stem other than the proximal head, such as a neck of the prosthesis. When force is applied to the impacting surface 7, the blade 5 may also be driven down along a side of the prosthesis. In certain embodiments, a cylinder sleeve is used and one or more blades are restricted to only moving about the axis of the sleeve cylinder. Devices with these and other restricted blade movements may further improve the efficiency and the quality of a surgical procedure.

[0034] The inner shaft 2 of the device 1 anchors the device to the prosthesis 10. For example, it may have threads for screwing into a receptacle, such as the threaded receptacle 11 of the prosthesis 10. In such embodiments, anchoring the inner shaft 2 to the prosthesis 10 is done by rotating the inner shaft 2 and its threads during attachment. The rotation can be facilitated by a knob 9 that is part of or attached to the inner shaft 2 and is manipulated or otherwise turned to cause the rotation of the threads. The knob 9 coupled to the inner shaft 2 may have a knurled surface to facilitate manual rotation of the inner shaft to screw the threads of the first portion into the hole of the prosthesis.

[0035] The outer sleeve 3 of the housing is configured to rotate about the shaft 2. A drive mechanism including the handle 4 is provided to rotate the outer sleeve 3, thereby rotating it about the inner shaft. Rotating the housing in this manner also causes the blade 5 to rotate about the exterior circumference of the prosthesis 10 to position the cutting surfaces of the blade between the prosthesis 10 and the tissues and cut the tissues away from the prosthesis.

[0036] The outer sleeve 3 and inner shaft 2 are generally both capable of rotating independently. For example, knob 9 and handle 4 shown in Figures 1 A-C are independently rotatable. A user can turn knob 9, thus rotating the inner shaft 2, while keeping the handle 4 and outer sleeve 3 static. This rotation allows a surgeon to attach or detach device 1 and a prosthesis, for example by turning threads on the distal end of inner shaft 2, without turning the outer sleeve 3 and blade 5. Keeping blade 5 static while the device 1 is attached or detached can reduce unintended cuts through surrounding tissue that can result from rotating blade 5 before device 1 is fully anchored. Likewise, while device 1 is attached to a prosthesis, the handle 4 and outer sleeve 3, as well as the blade 5 coupled to the outer sleeve 3, can be rotated while the inner shaft 2 and knob 9 remain static. This maintains a solid connection to the prosthesis during coupling, as the threads of the inner shaft 2 that hold the device 1 to the prosthesis do not rotate while the blade 5 is rotated for cutting.

[0037] The length of the outer sleeve 3 and/or inner shaft 2 can be configured so that one or more controls, such as handle 4 and/or knob 9, are manipulated without interference by the patient's body. The particular configuration of these components will depend upon the particular surgical scenario or scenarios for which they are designed.

[0038] In certain embodiments, the device has an inner shaft configured to be threaded into a driver hole of a hip prosthesis and an outer sleeve at least partially surrounding the inner shaft and includes a T-handle used to apply torque to a blade. The blade can extend from an outer circumferential surface of the outer sleeve. The outer sleeve can be configured to rotate or move the blade to separate the hip prosthesis from a bone in which the hip prosthesis is implanted. In certain implementations, the device has a first portion and a second portion. The first portion has an inner shaft structured to thread into the driver hole of the hip prosthesis. An outer sleeve surrounds the inner shaft and has a T-handle used to leverage the blade. The second portion, which may or may not be detachable from the first portion, has a blade that matches the outer circumference of a modular sleeve and, when used in conjunction with the first portion, will separate the implant from the bone.

[0039] Certain embodiments facilitate rotation or other movement of a blade positioned in a surgical site. One or more T-handles or other features can be used to apply torque so that such rotation causes the blade to cut through bone or other tissue.

[0040] According to certain embodiments, a method of removing a prosthesis involves attaching a device to the prosthesis within a surgical site. A first portion of the device is attached to the prosthesis to fix an orientation of a central axis of the device relative to the prosthesis. The device also has a second portion engaging the first portion. The second portion rotates independently from the first portion about the central axis and can be translated in a direction along the central axis. The second portion includes a blade.

[0041] After the device is fixed to the prosthesis, the method involves rotating the second portion, and thus the blade, of the device about the central axis to cut the prosthesis away from a bone in which the prosthesis is implanted. Such rotation of the second portion creates the cut by moving the blade in a path adjacent to one or more surfaces of the prosthesis. The method may further involve a surgeon striking a surface of the device to drive the blade into surrounding bone to separate the prosthesis from the bone. After detaching the prosthesis from the bone, the method may involve using the device to remove the prosthesis from the surgical site. For example, after bone is cut away, a surgeon may need to pull and rotate the implant to dislodge it from a fixed location. The surgeon may use the device attached to the prosthesis to apply any needed torque or force to dislodge and remove the implant.

[0042] The system, methods and devices may be implemented in multiple configurations, uses, and embodiments. A device could be a disposable or reusable instrument. The aforementioned first and second portions of a device could be broken into multiple modular pieces. For example, a T-handle or leverage handle could be separable, a cutting blade could be separable or adjustable, and the height of an outer sleeve and an inner shaft could be adjustable.

[0043] In certain circumstances, removal of a prosthesis may leave a portion within the bone. For example, a sleeve used with a hip stem may be left within a bone upon removal of the hip stem component. In this removal device may be used to remove the remaining sleeve portion after removal of the stem. Figure 3 illustrates an embodiment in which a device 40 is attached to a sleeve 30 to remove the sleeve from its implanted location in a bone 32. The removal device 40 is attached to the sleeve 30 by inserting the device 40 into the sleeve 30 until stopper 50, which is made of a bendable material such as a rubber, pliable plastic, or other suitable material, is positioned below the sleeve 30. The stopper 50 depicted in

Figure 3 includes first and second flanges 48 and 49. One or both of the flanges 48 and 49 is bendable to allow the stopper to fit through the distal end 47 of the sleeve, yet strong enough to maintain the position of stopper 50 after passing through the distal end 47 of the sleeve, and thus stably position the shaft 33 within the sleeve. Expanding devices, such as molly bolts, could also be used to maintain the position and orientation of the device 40 within the sleeve 30.

[0044] Once the device is attached to the implant, handles 42 and 44 can be used to move blade 46 down and/or around the sleeve 30. In this example, the device 40 includes a threaded, ratcheting, or other mechanism 45 that allows the blade 46 to move incrementally down along the side of the sleeve 30. For example, in the case of threading, as the handle 44 and attached blade 46 are rotated around the device, the blade 46 rotates around the sleeve 30 and gradually moves lower as the rotation follows the threading. In other embodiments, the rotation and lateral movement of the blade are separately controlled. For example, a ratcheting mechanism can be used to allow the blade 46 to be incrementally lowered into the bone. Once a desired depth is reached, the ratchet is locked and the blade 46 rotates around the sleeve 30 at the desired depth, without moving proximally or distally while it rotates.

[0045] A connection to a prosthesis can be established by pockets, ball-head tapers, threaded holes, adapters, contoured faces, or other design features specific to a certain prosthesis. The removal device used can be designed or adjusted to complement the connection mechanisms available on a given prosthesis.

[0046] A cutting blade may also have a variety of shapes to accommodate design features for specific prostheses or to improve the cutting function of the blade. For example, a spout or flange on an implanted prosthesis could prevent certain blades from fully separating the prosthesis from the bone. Accordingly, a blade may have a particular shape for use in cutting around a spout or other such prosthesis feature. Multiple blades may be used during prosthesis removal and can be interchanged to cut around different portions of an implant. As an example, one blade could be used to cut around a portion of the implant and another blade (e.g., a blade that is configured to cut at a different angle and/or distance from the device's perimeter) could be used to cut around some or all of a spout, a flange, or other portion of the implant. A blade can include shearing teeth. [0047] The methods and devices disclosed herein provide various advantages over prior devices and methods. Certain of the devices facilitate precise separation of a prosthesis and bone. Many prior removal techniques incorrectly rely on the assumption that an implanted prosthesis and host bone can be easily separated without any further damage to the patient. Methods and devices disclosed herein can be advantageous with respect to a potential situation in which bone and implantable prosthesis do not separate easily, and use of the methods and devices disclosed herein may reduce bone damage or other complications that may harm a patient, extend operating times, and/or introduce other risks. Certain embodiments further facilitate repeatable, accurate, and predictable cutting techniques useful in generally improving surgical cutting necessary for prosthesis removal and other surgical techniques. For example, certain embodiments help ensure that a sleeve can be explanted efficiently and accurately while reducing bone removal. The repeatability and accuracy of removal is advantageous in a hip revision. Freehand cutting and removal of implants may leave unpredictable and varied bone voids following removal of a femoral stem due to differences in surgeons' dexterity. The unpredictable void can make a subsequent revision implant difficult to place into the bone if the implant is not designed to fit the specific void. With the methods and devices disclosed herein, however, the repeatable cuts provide a more predictable void in the bone that can be anticipated in selecting a revision implant that closely matches the expected bone void.

[0048] Figures 4A-C illustrate mechanisms by which a device attaches to a prosthesis. Various coupling portions are shown attached to prostheses and coupled with cutting devices. Coupling portions to which cutting devices may be coupled include threaded shafts, ball-in-socket mechanisms, contoured surfaces, or any other suitable coupling mechanisms. Figure 4 A illustrates a cutting blade device 52 that attaches to and mechanically cooperates with a coupling portion 54. The coupling portion 54 may be part of the prosthesis when it is implanted into the bone, or may be coupled with the prosthesis during a revision procedure. For example, the coupling portion 54 may be connected to the prosthesis at an open receptacle on the prosthesis, such as a driver hole 51, during the revision surgery prior to attachment of a cutting device. The coupling portion 54 provides a coupling point, depicted in Figure 5 A as a ball-in-socket connection, for blade device 52 and acts as a pivot point about which blade device 52 rotates. The rotational axis created by coupling portion 54 is substantially aligned with and parallel to the center axis 57 of the implanted femoral stem 58 and sleeve 59. The dimensions of blade device 52, namely the length of arm 53, can be selected such that the blade is in close proximity to the implanted sleeve 59. As the blade device 52 is rotated to cut the bone, the blade remains in close contact with the sleeve 59 around substantially the full circumference of the sleeve 59, that close contact is maintained because the pivot point is substantially aligned with the center axis 57 of the stem 58 and the sleeve 59. By maintaining that close contact with the sleeve 59, a blade connected to the coupling portion 54 can cut away the stem 58 and the sleeve 59 while cutting less bone.

[0049] A cutting device could alternatively or additionally be used in cooperation with coupling portion 56, which is a ball and shaft coupling mechanism attached to the prosthesis by a plug. According to certain implementations, coupling portion 56 is used, for example, when an implanted prosthesis has a modular head and neck that can be removed, and the plug of the coupling portion 56 can be attached to the opening left by removing the neck from the prosthesis. A blade device, such as blade device 52, may have a second portion (not shown) that extends from arm 53 and attaches to coupling portion 56. The second portion is connected to arm 53 at a pivoting connection that allows the second portion to remain static and provide stability as the blade device 52 rotates and cuts through bone. Thus, when both coupling portions 54 and 56 are used, a connection at coupling portion 56 provides a stable anchoring point for a static portion of the blade device, while coupling portion 54 provides a pivot point for a rotating the blade of the blade device.

[0050] In certain implementations, an implanted prosthesis does not include the coupling portion 54 or a receptacle to receive the coupling portion 54. Rather, certain prostheses include only a modular neck and head that can be removed and replaced with coupling portion 56. A blade device for removing such a prosthesis includes a connection site for coupling to the coupling portion 56. The orientation of the coupling portion 56 is not substantially parallel to the center axis 57 of the implanted stem 58 and sleeve 59, and thus may not provide an adequate rotational axis for cutting around the sleeve 59. Thus, the blade device or mating component attached to the coupling portion 56 is modified to include a mechanism that creates a rotational axis substantially parallel to the center axis 57, as discussed below with respect to Figure 4B.

[0051] Figure 4B illustrates a cutting blade device 62 that attaches to and cooperates with a coupling portion 60. The coupling portion 60 is coupled with the implanted prosthesis 68 by a threaded connection at a driver hole 64 of the prosthesis 68. The blade device 62 is then placed over the coupling portion 60. The coupling portion 60 may be substantially similar to the inner shaft 2 discussed above with respect to Figures 1A-C and Figure 2, and the blade device 62 may be substantially similar to the blade 5 and outer sleeve 3 that rotate around the inner shaft 2. The coupling portion 60 is oriented substantially parallel to and aligned with the center axis 70 of the prosthesis 68 and thus provides a pivot point for the blade device 62 that reduces excess bone cuts during removal of the prosthesis 68. The blade device 62 may cut around the surface of the prosthesis 68 or around a surface of an implanted sleeve coupled to the prosthesis 68 (not shown), similar to the sleeve 59 of Figure 4 A.

[0052] A cutting device could alternatively or additionally be used in cooperation with coupling portion 66 at the tapered neck 72 of the prosthesis 68. In certain implementations, for example, the blade device 62 includes a second static portion which is coupled with the coupling portion 66 and pivotably attached to the blade device 62, providing stability to the blade device 62 as it rotates to cut around the prosthesis 68.

[0053] In certain implementations, the prosthesis 68 does not include the driver hole 64 or any other means of coupling the coupling portion 60 to the prosthesis 68, and a blade device can only be coupled to the coupling portion 66. In that scenario, the tapered neck 72 may not provide a suitable cutting axis, as the axis 76 of the tapered neck 72 is not substantially parallel to the center axis 70 of the prosthesis 68. To provide a more suitable pivot point for cutting, the coupling portion 66 includes an anchoring shaft 78 for coupling the blade device to the coupling portion 66. The anchoring shaft 78 creates an axis 74 that is substantially parallel to, though offset from, center axis 70 of the prosthesis 68. A blade device coupled with coupling portion 66 would then pivot about anchoring shaft 78 to cut surrounding bone. Because the anchoring shaft 78 is offset from the center axis 70, the blade device may be unable to stay in close proximity to the prosthesis 68 during a full rotation and thus may cut away more bone than desired around the anterior and posterior sides of the prosthesis, or may cut along an arc that passes outside of the bone. In such circumstances, a segmented blade device may be used to couple to the anchoring shaft 78 and facilitate a more accurate cut around the anterior and posterior of the prosthesis. The segmented blade may include a static portion that extends laterally from the anchoring shaft 78 and is coupled with a pivoting blade portion, with the pivot point of the blade portion located

substantially in line with the center axis 70. By locating the pivot point of the segmented blade substantially in line with the center axis 70, the blade is maintained in close proximity to the prosthesis 68 when it is rotated, and thus reduces the amount of bone that is cut away along the anterior and posterior sides of the prosthesis 68. In certain embodiments, the coupling portion 66 includes a lateral extension that extends in the direction of center axis 70 and contains an anchoring point that is substantially parallel to and aligned with the center axis 70. A blade device that includes only a single rotating cutting portion, such as the blade device 62, can then be used to couple with the anchoring point and cut around the prosthesis 68 while staying in close proximity to the surface of the prosthesis 68.

[0054] While the prostheses shown in Figures 4A and 4B have features for receiving or coupling with coupling portions to align a cutting device, some prostheses may lack such features. Figure 4C illustrates coupling portion 80 to which a cutting device could be coupled when a prosthesis, such as prosthesis 82, lacks features required to couple to other coupling portions. In contrast to prostheses 58 and 68, prosthesis 82 does not provide an attachment site for a coupling portion to align a blade device cutting axis with the central axis 86 of the implanted prosthesis 82 and sleeve 84. Instead, the coupling portion 80 is contoured to couple with the surface of the proximal end of the prosthesis 82. In particular, coupling portion 80 includes a hooked end 88 that matches a point 90 on the prosthesis 82 and provides a point for anchoring and alignment between the coupling portion 80 and the prosthesis 82. The coupling portion 80 is designed such that the ball 92 of the coupling portion 80 is aligned substantially with the central axis 86 of the prosthesis 82 when the hooked end 88 is positioned flush with the point 90. A blade device can be coupled to the ball 92 and use the ball 92 as a pivot point for cutting. Since the ball 92 and center axis 86 are substantially aligned, a blade device rotating around the ball 92 can be maintained in close proximity to the prosthesis 82 and the sleeve 84 to reduce the amount of excess bone cut away.

[0055] While Figures 4A-C depict ball heads, anchored shafts, and tapered necks for coupling a blade device to a prosthesis, a connection between a cutting or other removal device to a stem or other prosthesis can be established by other suitable means. As examples, one or more of the devices of the aforementioned

embodiments could be used or modified to fix to a stem by means of pockets, ball- head tapers, threaded holes, adapters, contoured faces, or other design features specific to the particular prosthesis involved.

[0056] Figures 5 A and 5B illustrate a cutting device 100 for use in prosthesis removal. The cutting device includes a block 104 and a blade 106. A through-hole 108 in the block 104 provides a means to couple the cutting device 100 to an implanted prosthesis or to a coupling portion that is integral with or attached to the implanted prosthesis. While a through hole is shown in Figures 5A and 5B, a threaded hole, socket, contoured surface, or any other suitable coupling mechanism may be included on block 104 to cooperate with a complementary attachment mechanism on a prosthesis or coupling portion. The through hole 108 sets the pivot point and rotation axis for the cutting device 100. The position of the through hole 108 and the dimensions of the block 104 are selected such that the rotation axis and distance from the axis to the blade 106 are suitable for a particular application. For example, the position of the through hole 108 may be designed, or cutting device 100 may be selected from a variety of cutting devices, such that operating the blade at a distance A from the through hole 108 produces a desired cutting arc for a certain prosthesis.

[0057] During a surgical procedure, the cutting device 100 is coupled to a prosthesis, coupling portion, or removal device, such as device 1 in Figures 1 A-C, and positioned such that blade 106 contacts bone into which the prosthesis is implanted. To position the cutting device 100 appropriately, a force may be required to push the blade 106 down into the bone. Such force is applied by contacting cutting device 100 on the impacting surface 102 of the block 104 to drive the blade 106 downward. Once positioned in the bone, cutting device 100 is engaged by a driving member that creates torque and causes cutting device 100 to rotate, cutting through surrounding bone as it moves.

[0058] Figures 6 A and 6B illustrate a cutting device 110 that includes block 114 and blade 116 with shearing teeth 112. The design and function of cutting device 110 may be substantially similar to cutting device 100 discussed above with respect to Figures 5A and 5B. The configuration or dimensions of block 114 and blade 116 may be different from block 104 and blade 106 to suit a particular application. For example, blade 116 has a wider profile, shown in Figure 6B, that may be desired in certain implementations. The shearing teeth 112 on blade 116 provide a cutting interface for cutting device 110 that may be preferred to the smooth, sharp cutting interface of blade 106 in cutting device 100. The shearing teeth 112 provide a rough edge that can easily cut through bone, both when the blade 116 is driven into the bone by hammering the impacting surface 118 and when rotating the cutting device 110 to cut an arc through the bone.

[0059] Figures 7 A and 7B illustrate a cutting device 120 having a rectangular configuration. Similar to cutting device 100 and 110, cutting device 120 includes a block 122 and blade 124. The blade 124 has a rectangular shape and is connected to the block 122 by the neck 126, which is narrower than the block 122 and blade 124.

[0060] The cutting device 120 configured for removing an implanted stem with a sleeve that has a spout shape, as is common in some femoral implants. Figure 8 A illustrates a front view of an implant 130 having a stem 132 and spout 134, and Figures 8B and 8C illustrate a side view and top view, respectively, of the implant 130. Since the spout 134 is not a cylindrical sleeve but rather has a teardrop shape around its top rim shown in Figure 8C, the center axis 140 of the stem 132 may not provide an adequate cutting axis for a blade, as the spout 134 is not symmetric about the stem 132. For example, a blade device, such as blade device 100, configured to rotate about axis 140 at a distance of B, shown in Figure 8C, would provide a cut in close proximity to the spout 134 along the circular portion of the spout, but would not be able to cut around the point of the spout due to interference from the rim 136 as the blade rotates around the spout 134 in a circular arc. In contrast, a blade device configured to rotate about axis 140 at a distance of C, shown in Figure 8C, would provide a cut from one side of the neck 142 of the implant 130 to the other side, but this cutting distance is larger than required to cut around the circular portions of the spout 134 and may result in the removal of excess bone.

[0061] Because of the configuration of cutting device 120 in Figures 7A and 7B, namely the size and position of the neck 126, the cutting device 120 can be used to avoid some of the complications of other blades when removing the spout 134. The neck 126 allows the cutting device 120 to cut further under the spout 134 than could be done by a straight blade and therefore allows the surgeon to cut into portions of the bone underneath the rim of the spout 134 that a straight blade is not able to reach. The spout 134 has a lower cylindrical portion 144 separated from the rim 136 of the spout 134 by a distance D, shown in Figure 8A. Accordingly, the cutting device 120 is configured such that the length of the neck, distance E shown in Figure 7B, is at least equal to the distance D and preferably slightly longer than the distance D. When the cutting device 120 is coupled to the implant 130 and rotated about axis 140 to create a cutting arc, the offset of blade 124 created by neck 126 maintains spacing between the sides 138 of the blade 124 and the rim 136 of the spout 134. The cutting device 120 can then be rotated around the device until the sides 146 of the neck 126 contact the rim 136, which positions the sides 138 of the blade 124 further underneath the spout 134 than a straight blade is able to reach, thus enabling a surgeon to make a more complete cut without removing excess bone.

[0062] In some implementations, the device is applied to only a portion of an implanted prosthesis, such as an implanted sleeve, and not the full implant.

Figures 9 A and 9B illustrate removal of a sleeve portion 200 of an implant 202 from bone 206 following the removal of a stem portion 204 of the implant 202. In certain implementations, the stem 204 more easily removed than the sleeve 200 and may be pulled out of the bone 206 while the sleeve 200 remains behind. For example, the sleeve 200 may have a textured surface that encourages bone ingrowth while the stem 204 has a smooth surface. Ingrowth of surrounding bone into sleeve 200 gives the bone 206 a tighter grip on sleeve 200 that may prevent sleeve 200 from moving when the stem 204 is pulled out of the bone.

[0063] A Cutting device 210 is used to remove the sleeve 200 after the stem 204 has been removed. A tapered plug 212, which is connected to a shaft 214, is placed into the sleeve and forced downward until interior sides 218 of the sleeve 200 compress the plug 212. The plug 212 is made of a pliable material, such as a rubber, plastic, or another suitable material, and is able to compress and exert an outward force on the sides 218 that maintains the position of the plug 212. When the plug 212 is in place, the shaft 214 is substantially parallel to and aligned with the center axis 216 of the sleeve 200 and thus provides a pivot point to which a cutting device, such as device 210, can be coupled.

[0064] The cutting device 210 is coupled to the shaft 214 by outer sleeve 220, which passes over the shaft 214 and sets the rotation axis of the device 210. A blade 222 is attached to outer sleeve 220 by arm 224, which is sized such that blade 222 is positioned in close proximity to the outer surface of the implanted sleeve 200. To drive the blade 222 into the bone and drive the outer sleeve 220 down onto the shaft 214, a force is applied at the impaction surface 226 on the arm 224. Once the blade 222 is in position, handle 228 of the device 210 is used to apply torque and rotate the device 210, creating an arced cut as the blade 222 passes around at least a portion of the perimeter of the sleeve 200 between the sleeve and the surrounding bone, to loosen the bone's grip on the sleeve and prepare for removal. After the device 210 is removed from the bone 206, the remaining shaft 214 and plug 212 are pulled upward, pulling shaft 214, plug 212, and sleeve 200 out of the bone. If the plug 212 pulls out of the sleeve 200, an auxiliary tool may be used to remove the loosened sleeve.

[0065] Figure 10 illustrates an adjustable blade according to certain

embodiments. In this implementation, a device 230 includes a shaft 232 attached to a tapered plug 234 that couples the device to an implanted sleeve 240, similar to the plug 212 and shaft 214 discussed above with respect to Figure 9B. An outer sleeve 236 fits over the shaft 232 and uses the shaft 232 as the pivot point for rotation of the device 230. The outer sleeve 236 is coupled with a blade 238 by a ratchet mechanism 242. The ratchet mechanism 242 allows for adjustment of the blade 238 to increase or decrease the distance from the blade 238 to the center of the shaft 232. Such adjustment allows a surgeon to change the size of an arc over which the blade 238 cuts. Accordingly, the device 230 can be adapted to different sleeves having different sizes and circumferences while still maintaining a close proximity between the blade 238 and the implanted sleeve during cutting.

[0066] Many prosthesis are made of metal or have polymer or other coatings that, if chipped during revision, can cause inflammation or other harmful effects. Figure 11 illustrates an embodiment of a blade 250 having a blunt tip portion 260 that separates the sharp cutting surface of the blade from the prosthesis thereby reducing the production of metal or other undesired shavings while cutting around an implant. In the depicted embodiment, the implant 352 has a porous coating 358, designed to encourage surrounding bone to grow into the implant 352, the blade 250 is coupled with implant 252 by a coupling portion 256 that is attached to the implant 252 at a threaded hole 254 in the implant. As the blade 250 is lowered into place, the blade contacts the stem of the implant 252. Contact between the blade 250 and the porous coating 258 can produce scratches and create metal shavings from the porous coating 258 that can cause infection or other undesired

complications if left in the bone from which the implant 252 is removed. To reduce the amount of rough contact between the blade 250 and porous coating 258, and thus the amount of metal shavings produced, the blunt portion 260, shown in the inset in Figure 11 , spaces the sharp tip portion 262 away from the implant, thereby creating a softer contact with the implant 252. As shown in the inset, the blunt portion 260 is positioned on the side of the blade 250 that faces and contacts the implant.

[0067] Figures 12A-C illustrate embodiments of blades each having a portion that contacts the outer surface of a prosthesis and an adjacent cutting portion.

Figure 12A depicts a blade 270 that has a blunted portion 272 and a sharp cutting portion 274 at its tip. Similar to the blade 250 in Figure 11, the blunted portion 272 contacts an implanted component and reduces scratching and production of metal shavings while cutting portion 274 provides an adequate interface to cut through surrounding bone.

[0068] Figures 12B and 12C show side and front views, respectively, of a blade 280 that includes a blunted portion 282 and sharp cutting portion 284. Similar to blade 270, blunted portion 282 creates a soft contact with a prosthesis while cutting portion 284 provides a sharp interface to cut through bone. In contrast to blade 270, blade 280 is angled to provide closed contact with an angled surface of an implanted component. To further reduce metal shavings that might be caused by the close contact, the blunted portion 282 may extend up the entire interior length of the blade 280 that contacts the prosthesis.

[0069] The foregoing is merely illustrative of the principles of the disclosure, and the systems, devices, and methods can be practiced by other than the described embodiments, which are presented for purposes of illustration and not of limitation. It is to be understood that the systems, devices, and methods disclosed herein, while shown for use in acetabular systems, may be applied to medical devices to be used in other surgical procedures including, but not limited to, spine arthroplasty, cranio-maxillofacial surgical procedures, knee arthroplasty, shoulder arthroplasty, as well as foot, ankle, hand, and extremities procedures.

[0070] Variations and modifications will occur to those of skill in the art after reviewing this disclosure. The disclosed features may be implemented, in any combination and subcombinations (including multiple dependent combinations and subcombinations), with one or more other features described herein. The various features described or illustrated above, including any components thereof, may be combined or integrated in other systems. Moreover, certain features may be omitted or not implemented.

[0071] Examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the scope of the information disclosed herein. All references cited herein are incorporated by reference in their entirety and made part of this application.