US4873969A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for removal of bone cement
Assignee: Individual
•
Filing: 1988-08-15
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Granted: 1989-10-17
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Expires: 2008-08-15
Abstract
Abstract Bone cement is removed from a bone cavity, such as the intramedullary canal, during a prosthetic revision. The bone cement is pre-molded by a thermal chisel which includes a shaft for extending into the bone cavity, a plasticizer chisel on a working end of the shaft, and a heat element carried by the shaft for heating the chisel to a temperature within a range of temperatures sufficient to plasticize the bone cement. This deforms and weakens the bone cement upon direct non-impact type contact between the heated tip of the chisel and the cement. The cement is removed by pre-molding it with the heated working end of the thermal chisel, preferably by molding a distally located circumferential furrow in the bone cement and then molding circumferentially spaced apart longitudinal furrows from the circumferential groove to the proximal end of the bone cement. Upon rehardening of the bone cement, these thermally molded furrows form weakened areas within the bone cement so that the regions of bone cement between the weakened areas can be removed by an impact type chisel. Preferably, each section of bone cement is removed intact by impact force applied to a molded step groove in a proximal end surface of the section. Removal of the bone cement in sections by these procedures avoids harmful heat transfer to the bone wall.
Inventors
- 👤 Donald L. Huebsch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:09
CPC Classifications
A; A61; A61B; A61B17/00; A61B17/56; A61B17/58; A61B17/88; A61B17/8802; A61B17/8847; A61B17/16; A61B17/1604; A61B18/00; A61B18/04; A61B18/08; A61B18/082; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/46; A61F2002/465
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
160 words
A process for removing bone cement from a bone cavity during a prosthetic revision, comprising: providing a surgical instrument having a heated tip at its working end and a heat element carried by the instrument for heating the tip; heating the tip by the heat element to a temperature sufficient to mold one or more grooves into the bone cement upon direct contact by the heated tip of the surgical intrument; insert the heated tip into the bone cement to mold one or more grooves into it, removing the heated tip and, allowing the bone cement to reharden which produces weakened areas in the bone cement in the vicinity of the molded grooves, placing a surgical impact type chisel against the sections of the bone cement between said weakened areas, and removing the sections of bone cement by direct impacting of the chisel; and repeating the molding and impacting steps until substantially all bone cement is removed from the cavity.
Claim 2
Dependent Claim
160 words
A process for removing bone cement from a bone cavity during a prosthetic revision, comprising: providing a surgical instrument having a heated tip at its working end and a heat element carried by the instrument for heating the tip; heating the tip by the heat element to a temperature sufficient to mold one or more grooves into the bone cement upon direct contact by the heated tip of the surgical intrument; insert the heated tip into the bone cement to mold one or more grooves into it, removing the heated tip and, allowing the bone cement to reharden which produces weakened areas in the bone cement in the vicinity of the molded grooves, placing a surgical impact type chisel against the sections of the bone cement between said weakened areas, and removing the sections of bone cement by direct impacting of the chisel; and repeating the molding and impacting steps until substantially all bone cement is removed from the cavity.
Claim 3
Dependent Claim
57 words
The process according to claim 1 in which a step groove is molded thermally in a proximal surface of the weakened sections of the bone cement, and the chisel tip of the impact chisel has a shape similar to the molded step groove for use in applying an impact force to each weakened section of bone cement.
Claim 4
Dependent Claim
18 words
The process according to claim 1 in which the instrument includes internal and external battery powered heating elements.
Claim 5
Dependent Claim
17 words
The process according to claim 3 in which the heating elements are of less than 24 volts.
Claim 6
Dependent Claim
73 words
The process according to claim 1 in which the tip of the heated instrument is pointed and mounted normal to the working end of the instrument; and the tip is used to make a circumferential furrow distally in the cement along with a plurality of longitudinal furrows spaced apart circumferentially around the region of bone cement, for forming the weakened sections of bone cement between the longitudinal furrows and above the circumferential furrow.
Claim 7
Dependent Claim
48 words
The process according to claim 5 in which a molded step groove is formed at the proximal surface end of each of the sections of bone cement between adjacent longitudinal furrows to provide a means for forming a bearing surface for the impact force of the impact chisel.
Claim 8
Dependent Claim
33 words
The process according to claim 6 in which each section of the bone cement is removed by placing the impact chisel in the proximal groove of a respective section and impacting the chisel.
Claim 9
Dependent Claim
25 words
The process according to claim 7 in which a plurality of circumferentially spaced apart longitudinal furrows are molded in the bone cement prior to impact.
Claim 10
Dependent Claim
19 words
The process according to claim 8 in which the furrows are molded approximately 25% distal in the bone cement.
Claim 11
Dependent Claim
144 words
A surgical instrument for removing bone cement from a bone cavity, comprising: an elongated shaft of sufficient length to extend far enough into the cavity to mold the bone cement therein; a plasticizer chisel mounted on a working end of the shaft; a heat element carried by the shaft for heating the chisel to a temperature within a range of temperatures sufficient to plasticize the bone cement and thereby deform and weaken it upon direct non-impact type contact between the heated chisel and the bone cement; and at least one tangential point protection member projecting from the shaft adjacent the working end of the instrument to provide point contact with the wall of the bone upon contact between the instrument and the bone wall so as to prevent damaging heat transfer from the working end of the instrument to the wall of the bone.
Claim 12
Dependent Claim
144 words
A surgical instrument for removing bone cement from a bone cavity, comprising: an elongated shaft of sufficient length to extend far enough into the cavity to mold the bone cement therein; a plasticizer chisel mounted on a working end of the shaft; a heat element carried by the shaft for heating the chisel to a temperature within a range of temperatures sufficient to plasticize the bone cement and thereby deform and weaken it upon direct non-impact type contact between the heated chisel and the bone cement; and at least one tangential point protection member projecting from the shaft adjacent the working end of the instrument to provide point contact with the wall of the bone upon contact between the instrument and the bone wall so as to prevent damaging heat transfer from the working end of the instrument to the wall of the bone.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-16 | 1993-04-17 | 1993-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-16 | 1997-04-17 | 1997-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-16 | 2001-04-17 | 2001-10-17 | $7700.00 | Window Closed / Lapsed |