Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1998-02-19
2001-03-06
Buiz, Michael (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S100000
Reexamination Certificate
active
06197032
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a profile gauge for measuring and indicating the diametric profile of a bone opening and is particularly, although not exclusively, applicable for use with an acetabular cup loading tube which is provided with a skirt.
2. Description of the Prior Art
In certain surgical operations it is convenient to be able to measure the diametric profile of a bone opening, for example, if a plate of specific size is to be used or if an acetabular cup is to be implanted into an acetabular socket.
U.S. Pat. No. 5,527,317 shows an apparatus for implanting an acetabular cup employing a loading tube adapted for alignment with an acetabular socket. The bore of the tube being dimensioned to receive an acetabular cup as a sliding fit to guide it into the socket and the present invention can provide a profile gauge which can be used with such a loading tube.
If a rim cutter is used to produce a step inside the bony rim of a natural acetabulum, two problems can arise. Firstly it demands a very high level of surgeon patience, care, calmness, experience, determination and skill to position the cutter accurately and hold it on course. Otherwise, the cutter can cut eccentrically and find its own orientation. Secondly, many acetabulae are insufficiently circular to allow the rim cutter to prepare a ledge around much more than about 180° and this does not permit a loading tube to seat and seal.
Furthermore, where in revision surgery, bone chips are used to reform the acetabulum the rim cutter cannot cut the recess in a bed of loose morsels of bone. Sometimes a bone graft is contained in a surgeon formed metal mesh which in turn can be anchored by bone screws. With this arrangement a rim cutter must not be used to cut this metal mesh inside the patient.
In order to overcome the difficulties, the proposed solution for both non-circular and bone chip acetabular rims is to avoid the rim cutting operation and to trim the skirt of the loading tube so that it accurately fits the bony (or grafted) acetabular rim. Thus the skirt can be trimmed to fit either within the rim or around it.
SUMMARY OF THE INVENTION
According to one object of the present invention, a profile gauge for use with an acetabular cup loading tube provided with a skirt comprises adjustable elements for measuring and indicating the diametric profile of the mouth of the rim area adjacent thereto of an acetabular socket into which an acetabular cup is to be implanted. The gauge includes a device for removably locating the adjustable elements on a loading tube to indicate on the skirt thereof the measured diameter profile.
Thus the profile gauge is used to measure the socket and the measurement can be transferred accurately to the skirt of the loading tube. Preferably, the adjustable elements include a body portion and a number of peripherally projecting indicators which can be adjusted to define the shape of the mouth of the socket. The indicators can thus be provided by axially movable pins and these can be held in place by friction between each pin and the body portion.
The body portion can be substantially annular, the indicators projecting outwardly from the periphery thereof and also inwardly into the central opening. Preferably, the device for removably locating the adjustable elements includes a plug adapted to engage and fit within the bore of the loading tube with which the gauge is to be used and said plug can be removable from the adjustable elements. The gauge can be provided with a positioning rod for axially locating it in relation to the mouth of the socket to be measured.
Thus the positioning rod can include a trial cup and can include a cup plug which can be located on or in the trial cup and to which the adjustable elements are connected. The connection between the cup plug and the adjustable elements can be detachable. In a preferred construction, the projecting indicators have a dished configuration adapted to be substantially parallel to the projecting angle of the skirt on the loading tube with which they are to be used.
According to another object of the present invention a profile gauge for measuring and indicating the diametric profile of a bone opening or the rim area adjacent thereto comprises a body portion and a number of peripherally projecting indicators which can be adjusted to define the profile or the rim area adjacent thereto of the opening in the bone to be measured.
Thus, with this construction, the general arrangement can be similar to that set forth above with or without means for locating the adjustable means in the bone opening to be measured.
These and other objects and advantages of the present invention will become apparent from the following description of the accompanying drawings, which disclose several embodiments of the invention. It is to be understood that the drawings are to be used for the purposes of illustration only and not as a definition of the invention.
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Lawes Peter
Ling Robin S. M.
Buiz Michael
Howmedica International Inc.
Lerner David Littenberg Krumholz & Mentlik LLP
Ngo Lien
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