Surgery – Instruments – Orthopedic instrumentation
Patent
1996-07-09
1998-10-06
Buiz, Michael Powell
Surgery
Instruments
Orthopedic instrumentation
606 80, 606 89, 606205, A61B 1717
Patent
active
058170987
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The invention relates to the field of hip joint prostheses for permanent anchorage in the human hip joint. More specifically, the invention relates to a drill guide instrument for guiding a drill tool when drilling a longitudinal bore through the neck (collum femoris) of the human femur, subsequent to a resection of the head (caput) of the collum. The invention also relates to the use of such an instrument, as well as a method for drilling such a bore.
BACKGROUND ART
The invention being especially, but not exclusively, applicable to the anchorage of hip joint prostheses of the type disclosed in WO 93/16663, the technical background to the invention will be described with specific reference to this document and the problems encountered when mounting a hip joint prosthesis of the type disclosed therein. However, the invention is applicable also to other types of hip joint prostheses.
WO 93/16663 discloses a hip joint prosthesis comprising an attachment part for a ball unit designed to be anchored in the neck of the human femur (collum femoris). The attachment part comprises a part for carrying a ball or caput intended to be attached to the collum after a resection of the head of the collum has been performed. The attachment part also comprises a fixture member having two main parts, namely a first part which is to extend through a bore extending from the collum towards the outer side of the femur, and a plug-like second part intended to fit into a cylindrical recess cut in the cancellous bone of the collum. A hip joint prosthesis of this kind is illustrated in FIG. 1 of the accompanying drawings. Further examples of prior-art hip joint prostheses are disclosed in WO 93/01769 and WO 89/11837.
In order to obtain a strong anchorage of the prosthesis, the plug-like second fixture part may be brought into engagement with the inside of the cortical bone in the collum, as discussed in general terms in WO 93/16663, since a direct contact with the cortical bone will reduce the risk of mechanical loosening of the prosthesis. However, any perforation of the cortical bone of the collum must be avoided, as discussed in the same document. Especially, the cortical bone must not be perforated by the cylindrical recess or by the plug-like part received therein. Since the cylindrical recess is concentric with the drilled bore and actually is cut in the collum with the aid of the drilled bore as guide channel, the longitudinal bore must be drilled through the collum along an axis having a predetermined orientation and a predetermined position relative to the collum in order to obtain the aimed-at engagement between the plug-like fixture part and the cortical bone.
It is, therefore, an object of the invention to enable high-precision drilling of a longitudinal bore through the collum of the human femur along a drill axis having a predetermined orientation and a predetermined position relative to the collum.
It is also an object of the invention to enable expedient and reliable high-precision drilling of this type.
Especially, it is an object of the invention to orient and position the drill axis in such a way that a hip joint prosthesis subsequently anchored in the collum will firmly engage the cortical bone of the collum, while reducing the risk of any perforation of the cortical bone.
A particular object of the invention is to provide a drill guide instrument by means of which both the orientation and the position of the drill axis relative to the collum can be determined in a reliable and accurate manner, and which can be used for guiding a drill tool or the equivalent along the drill axis thus established.
DISCLOSURE OF THE INVENTION
These and other objects of the invention are achieved by a drill guide instrument and method, as well as the use of such an instrument, having the features set out in the appended claims.
Thus, a drill guide instrument according to the invention comprises a drill guide provided with a base member and arranged to guide the drill tool along a drill axis rel
REFERENCES:
patent: 5417695 (1995-05-01), Axelson, Jr.
Albrektsson Bjorn
Carlsson Lars
Jacobsson Magnus
Rostlund Tord
Wennberg Stig
Astra Aktiebolag
Buiz Michael Powell
Reip David O.
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