Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-04-25
2001-09-04
Hirsch, Paul J. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C606S079000
Reexamination Certificate
active
06283971
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to reaming systems and, more particularly, to an expandable reaming system for reaming an acetabulum in preparation for implanting a prosthetic component, such as an acetabular cup or socket.
Acetabular hip surgery involves reforming the normal hip socket, or acetabulum, so that a proper bearing surface for the ball of the femur is established and which will support normal motion of the leg. The acetabulum needs to be shaped so that it can receive a metallic or plastic artificial socket. To ensure a proper fit of the artificial socket, deteriorated or diseased bone is cut away until healthy bone becomes visible. Typically, reamer heads of increasingly larger size are required as bone is cut away and the socket is enlarged. Each time a larger reamer head is needed, the reaming system must be removed from the patient's acetabulum, the reamer head is removed from the drive shaft of the surgical drill, and the next larger reamer head is attached thereto. This sequence may be repeated several times until the acetabulum is completely prepared to receive an acetabular prosthetic implant.
Several types of acetabular reamer heads are known in the art. Further, a surgical expansive reamer for hip sockets is taught in U.S. Pat. No. 3,702,611. Having to swap reamer heads multiple times during a hip surgery, as discussed above, is inconvenient, inefficient, and may even lead to surgical errors in that the angle of acetabular penetration cannot be accurately preserved during reamer head substitutions. Further, the '611 reamer is also inefficient in that it requires the acetabulum to be prepared with another instrument prior to its use and does not include a satisfactory mechanism for accurate incremental expansion of the reamer.
Therefore, it is desirable to have a reaming system which can be used to prepare an acetabulum to receive an artificial socket without having to substitute one reamer head for another. It is further desirable to have a reaming system having a reamer head which is manually expandable to a plurality of desired sizes.
SUMMARY OF THE INVENTION
An expansible acetabular reaming system according to a preferred embodiment of the invention includes a reamer head having a convex forward surface and a base plate which together form an interior space therebetween. The forward surface includes a plurality of spaced apart apertures extending therethrough. The base plate also includes a central aperture. A flexible bladder is mounted within the interior space of the reamer head and is sealed around the central base plate aperture. The bladder is concentric to the generally hemispherical shape of the forward surface and, even when inflated, is spaced apart therefrom. A plurality of cutter blades are fixedly attached to the bladder and extend outwardly therefrom. The blades are spaced apart from one another and are positioned to correspond to respective apertures in the convex surface.
An air cylinder depends from the base plate of the reamer head and includes an open top positioned immediately adjacent the central aperture of the base plate for communicating the bladder with the air cylinder. The air cylinder includes a bottom wall having a threaded bore through which a threaded shaft extends. The end of the threaded shaft which extends from the air cylinder is coupled to a thimble-type knob. A disc-like platform is attached to the opposing shaft end within the air cylinder. Therefore, as the knob is turned in a first direction by a user, the shaft is threadably rotated so as to force air within the cylinder into the bladder. As the bladder is inflated, the blades are projected through respective corresponding apertures in the convex forward surface. Conversely, as the knob is turned in an opposing direction thereby deflating the bladder, the blades are retracted through the apertures.
Scale indicia are provided on the exterior of the air cylinder housing such that the blades may be extended or retracted to particular positions during a hip replacement surgical operation. This expandability is significant in that traditional hip replacement surgeries require the use of multiple acetabular reaming heads of increasingly larger sizes. According to the present invention, the effective size of the reamer head may be adjusted as desired without needing to remove the head from the acetabulum; instead adjustment may be accomplished by turning the knob to the desired size as indicated by the scale. Even if the reamer head is removed from the acetabulum, adjustment can be made quickly as the reamer head need not be removed and replaced. The reaming system includes a socket adapted to be removably attached to the drive shaft of a surgical drill.
Therefore, a general object of this invention is to provide a reaming system which can completely prepare an acetabulum to receive an artificial socket without having to substitute one reamer head for another.
Another object of this invention is to provide a reaming system, as aforesaid, which reduces the amount of time required to conduct an acetabular hip replacement surgery.
Still another object of this invention is to provide a reaming system, as aforesaid, having a plurality of blades which project or retract through a reamer head according to a desired reamer head size.
Yet another object of this invention is to provide a reaming system, as aforesaid, in which the degree of projection or retraction of the reaming blades is manually controlled by user actuation of an air bladder.
A further object of this invention is to provide a reaming system, as aforesaid, having a reservoir within the reamer head which can collect bone and viscous fluids.
A still further object of this invention is to provide a reaming system, as aforesaid, having a reamer head which can be expanded in ½ mm increments.
Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, embodiments of this invention.
REFERENCES:
patent: 3702611 (1972-11-01), Fishbein
patent: 4782833 (1988-11-01), Einhorn et al.
patent: 5299893 (1994-04-01), Salyer et al.
patent: 5462548 (1995-10-01), Pappas et al.
patent: 5830215 (1998-11-01), Incavo et al.
patent: 5919195 (1999-07-01), Wilson et al.
patent: 5925056 (1999-07-01), Thomas et al.
Hirsch Paul J.
Priddy Michael B.
Ream Dale J.
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