The invention relates to surgical tools for aiding a surgeon installing an orthopedic prosthesis. More specifically, the invention relates to an orthopedic cup impactor for positioning an acetabular cup prosthesis within the body.
A total hip replacement is a reconstructive surgical procedure typically performed by an orthopedic surgeon. A total hip replacement involves placement of an acetabular cup within a patient's acetabular socket and replacement of the patient's femoral neck with a prosthesis which terminates in a ball specifically designed to be positioned in the acetabular cup. Other surgical procedures may require the application of an acetabular cup or other device applied to a patient.
For example, during such acetabular cup procedures, the patient's acetabular socket is reamed out by the surgeon so as to create an enlarged recess to receive the acetabular cup. After the acetabular socket has been reamed, the cup is inserted into the recess and adjusted as necessary to the proper angular orientation. Once deployed, the cup provides a new socket and lining for the patient's acetabulum.
Insertion and placement of the cup by the surgeon is effected either by hand or use of a hand tool that grips the cup. Once the cup is properly positioned in the acetabulum, the cup can be fixed in the desired location by various means such as bone screws, medically acceptable adhesives, or combinations thereof. In many instances, the fixation means include passing bone screws through the cup and into pre-drilled screw holes in the pelvic bone. The bone screws, which are optional, serve to hold the acetabular cup in the acetabulum until bone ingrowth provides permanent fixation.
In one acceptable medical method, the cup is properly positioned in the acetabulum by implantation. One conventional implantation method is, after obtaining proper alignment, to impact an acetabular cup into place. While impacting the acetabular cup, the surgeon listens for a change in pitch as the cup seats down. The surgeon then probes screw holes to determine if a gap between the cup and the bone is present. If a gap is present, the surgeon further impacts the cup into the acetabulum.
The tool thread section 24 threadingly interconnects to a surgical implant device (a.k.a., medical attachment) 26, for example, and not limited to, an acetabular cup, through a threaded aperture 28 (
The rotate handle 30 is positioned in the spacing between the tool thread section 24 and the impactor thread section 20. At its proximal end, the rotate handle device 30 has a rotating threaded section 32 and at its distal end, an implant support 34. The rotating threaded section 32 has threads that mate with the impactor thread section 20. When the rotating threaded section 32 is rotated clockwise (illustrated by arrow 36 at
However, when the surgeon impacts the strike plate 12 there is a possibility that the surgical implant 26 can disconnect from the impactor 10. This could occur when the threaded section 24 or the implant's 26 corresponding threaded section 28 is damaged from the impaction force. Accordingly, what is needed is a firm fixation of the surgical implant 26 during impaction that provides minimal damage to the implant's 26 threads 28. That desired product is achieved with the present invention.
The cup impactor of the present invention comprises an elongated body with respective distal and proximal ends. The elongated body is constructed with a strike plate residing at the body's proximal end, a handle portion, and an impactor cup engagement portion located at the body's opposing distal end. The elongated body is constructed of a one-piece design. The elongated body is designed such that the strike plate fluidly extends from the proximal end portion to the handle portion through a body length portion and to the impactor cup engagement portion at the distal end portion.
A connection rod, having respective proximal and distal rod ends, is positioned within an elongated through-bore of the body and housing portions. The distal end of the connection rod is constructed with a threaded end that is designed to threadably attach to a threaded aperture of a prosthetic orthopedic cup. The proximal end portion of the connection rod resides within the handle through-bore such that the rod's proximal end does not contact the inside wall surface residing at the proximal end of the impactor at the handle.
Therefore, because the proximal end of the connection rod is prevented from contacting the inner surface of the proximal end of the cavity of the handle, the possibility that impaction forces are transferred to the surgical implant through the connection rod, is reduced. As a result, the possibility of causing damage to the cup implant, particularly the prosthetic cup's connection mechanism, is reduced.
In an embodiment of the impactor of the present invention, the proximal end portion is pivotably connected to a lever arm subassembly comprising a lever arm and linkage member. This lever arm subassembly actuates movement of the connection rod and thus movement of the prosthetic cup. The lever arm subassembly is designed such that when the lever arm is moved in a pivotable manner in a downward direction, i.e., closer to the external surface of the handle's annular sidewall, the connection rod is retracted into the through-bore of the body. Since the distal end of the connection rod is preferably connected to the prosthetic cup, retraction of the rod within the body pulls the implant cup in a proximal direction, closer to the cup engaging portion of the impactor. Likewise, when the lever arm is pivoted away from the external surface of the annular sidewall of the handle, the connection rod and, therefore, the prosthetic cup, move distally away from the distal end of the impactor.
In a further embodiment of the impactor of the present invention, a releasable ratchet locking mechanism is provided. The locking mechanism enables the prosthetic cup to be locked in a multitude of positions with respect to the impactor. The locking mechanism release lever further allows for quick release and removal of the prosthetic cup from the impactor.
In yet another embodiment of the impactor of the present invention, the one-piece construction of the impactor body portion of the impactor minimizes the possibility that the associated components of the impactor are misplaced. The impactor is constructed such that its components are either connected to or contained within the elongated body or handle portions, thereby preventing displacement of the components from the impactor.
Now turning to the figures,
More specifically as illustrated in
The elongated body portion 60 is constructed with a curved body sidewall 68. More preferably, the elongated body portion 60 is constructed with an annular body sidewall 68 with an outer diameter ranging from about 1 cm to about 5 cm. Although it is preferred that the elongated body is constructed with a sidewall 68 having a circular cross-section, the body 60 may be constructed of, a multitude of cross-sectional shapes that include, but are not limited to, a rectangle, a square, triangle, a hexagon, or an oval.
The elongated body portion 60 has a length that ranges from about 5 cm to about 50 cm and more preferably from about 10 cm to about 25 cm. The body portion 60 may be constructed of either a polymer, metallic, or composite material. Specifically, the body portion 60 may be constructed from polymers comprising polyether ether ketone (PEEK), acryloyl b-alanine (ABA), acryloyl b-alanine tri-block copolymers and the like. In addition, the body portion may be constructed from metals comprising aluminum, stainless steel, cobalt nickel alloys, highly alloyed ferritic stainless steel containing molybdenum and chromium, and nickel chromium- and molybdenum-containing alloys, and the like. Furthermore, the body portion 60 may be constructed from composite materials such as carbon fiber or combinations of polymeric and metallic materials.
As shown in
Extending proximally from the elongated body portion 60 is the handle portion 62 of the impactor 50. As shown in
The handle portion 62 preferably has an inner handle diameter ranging from about 1 cm to about 3 cm. A handle through-bore 80 extends longitudinally along axis A-A from a handle distal end 82 to a handle proximal end 84. The handle through-bore 80 is aligned with the elongated body through-bore 70 along longitudinal axis A-A.
The handle portion 62 has a length that ranges from about 5 cm to about 50 cm and more preferably from about 10 cm to about 25 cm. Like the elongated body portion 60, the handle portion 62 may be constructed of either a polymer or metallic material. The handle portion 62 may be constructed from polymers comprising polyether ether ketone (PEEK), acryloyl b-alanine (ABA), acryloyl b-alanine tri-block copolymers and the like. In addition, the handle portion may be constructed from metals comprising aluminum, stainless steel, cobalt nickel alloys, highly alloyed ferritic stainless steel containing molybdenum and chromium, and nickel chromium- and molybdenum-containing alloys, and the like.
In an embodiment, the proximal end 84 of the handle portion 62 comprises a cavity 86. The cavity 86 extends completely through the thickness of the annular sidewall 78 of the handle portion 62, but only for a portion of the annular extent of the sidewall 78. This structure provides the cavity 86 having a channel shape that extends from the proximal end 84 of the handle 62 to a point, distal of the handle portion's proximal end 84. In a preferred embodiment, the cavity 86 has a length ranging from about 5 cm to about 15 cm and a depth and width that spans the distance between opposed inner surfaces of the annular handle sidewall 78.
Positioned within the elongated body and handle portions 60, 62 is the connection rod 64. The rod 64 is constructed such that it is in a slidable relationship within the through-bores of the elongated body and handle portions 60, 62. The connection rod 64 has a rod proximal end portion 88 spaced apart from a rod distal end portion 90 with a rod length residing therebetween. The connection rod 64 is preferably positioned within the through-bore 70 of the body 60 such that its proximal end portion 88 extends past the proximal end 76 of the body 60 and resides within the handle portion 62. More specifically, the proximal end portion 88 of the connection rod 64 extends within the handle portion 62 to a point distal of the handle's proximal end. A gap resides between the proximal end of the connection rod 64 and the proximal end of the handle portion 62. When the connection rod 64 is positioned within the impactor 50, a portion of the proximal end of the connection rod 64 is viewable through the cavity 86 of the handle 62. At the opposite end of the impactor 50, the distal end portion 90 of the rod 64 protrudes through a distal end 92 of the elongated body 60.
The connection rod 64 has a length ranging from about 5 cm to about 50 cm and more preferably from about 10 cm to about 20 cm. The connection rod 64 has a curved cross-section and more preferably, a circular cross-section. In a preferred embodiment, the rod 64 has a cross-sectional diameter ranging from about 0.5 cm to about 4 cm. Similarly to the body portion 60, as previously described, the rod 64 may be constructed of a multitude of cross-sectional shapes that include but are not limited to, a rectangle, a square, a triangle, a hexagon, or an oval. In a preferred embodiment, the connection rod 64 may be constructed from metals comprising aluminum, stainless steel, cobalt nickel alloys, highly alloyed ferritic stainless steel containing molybdenum and chromium, and nickel-, chromium- and molybdenum-containing alloys, and the like. Alternatively, the connection rod 64 may be constructed from polymers comprising polyether ether ketone (PEEK), acryloyl b-alanine (ABA), acryloyl b-alanine tri-block copolymers and the like. In addition, the connection rod 64 may be constructed from composite materials such as carbon fiber or combinations of polymeric and metallic materials.
In a preferred embodiment, a distal end 94 of the rod 64 has a threaded end that is designed to engage with a threaded receiving end of the prosthetic cup 56. As shown in
As illustrated in
The strike plate 58 resides at the opposite, proximal end of the handle portion 62. The strike plate 58 is designed with a strike plate diameter that is wider than the outer diameter of the handle 62. In a preferred embodiment, the diameter of the strike plate 58 ranges from about 2 cm to about 10 cm. As illustrated, the strike plate 58 is fluidly attached to the proximal end of the handle 62.
As shown in
As illustrated in
The lever arm connection pin 122 extends perpendicularly through the lever arm through-bore 124 and connects with a corresponding lever arm support portion 128 (
The lever arm subassembly 100 is designed such that when the lever arm 104 is moved in a pivotable manner in a downward direction, towards the exterior surface of the handle portion 62, the distal end 118 of the lever arm pulls the proximal end of the connection rod 64 towards the proximal end of the handle portion 130. More specifically, when the lever arm 104 is moved in a pivotable manner in a downward direction, the distal end handle protrusion 130, which is connected to the proximal end of the connection rod 64, is moved in a proximal direction to the proximal end of the handle portion 62, thereby pulling the proximal end of the connection rod 64 towards the proximal end of the handle portion 62. As a result, the distal end 94 of the rod 64 is retracted within the body portion 60 of the impactor 50.
Therefore, when a prosthetic cup 56 is attached to the distal end 94 of the connection rod 64, proximal movement of the rod 64 pulls the cup 56 closer to the distal end of the elongated body 60 as shown in
As shown in
As shown, a rocker pivot pin 148 resides through a rocker arm through-bore 150 and through the sidewall 146 of the ratchet housing 140 such that the rocker arm 136 is capable of pivoting about the pin 148. Therefore, when the proximal end 152 of the rocker arm 136 is moved in a downward direction, toward the outer surface of the housing 62, the opposite distal end 142 of the rocker arm 136 moves in an opposite upward direction, thereby disengaging the rocker teeth 154 from the connection teeth 158 (
As shown in
The bias member 138 is positioned within the rocker mechanism housing 140. As shown in
Although a threaded screw fitting is the preferred means of attachment of the prosthetic cup 56 to the impactor 50 of the present invention, other cup attachment means could also be used. For example, as illustrated in
Once the prosthetic cup 56 has been securely connected to the distal end of the impactor 50, the impactor and prosthetic cup assembly is inserted within the target area of the acetabulum. Once correctly positioned, a series of impaction forces are delivered to the strike plate 58 to thusly seat the cup 56 in the acetabulum. After the cup 56 is secured within the acetabulum, the impactor 50 is removed from the seated cup. This separation is accomplished by depressing the rocker lever 152 of the ratchet locking mechanism 134. This action raises the distal end portion 142 of the rocker arm 136, disengaging the rocker arm teeth 154 from the teeth 158 of the connection rod 64, thereby enabling the connection rod 64 to move freely within the body and handle portions 60, 62. This rocker arm 136 movement enables the connector rod 64 to extend distally. The strike plate 58 is then rotated in a counter clockwise direction to disengage the prosthetic cup 56 from the connection rod 64 and the body of the impactor is removed from the patient.
Accordingly, the invention is not limited, except by the appended claims.
This application claims priority from U.S. Provisional Patent Application Ser. No. 61/527,684, filed Aug. 26, 2011.
Number | Date | Country | |
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61527684 | Aug 2011 | US |