US5064426A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for removal of bone cement
Assignee: Individual
•
Filing: 1989-03-07
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Granted: 1991-11-12
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Expires: 2009-03-07
Abstract
Abstract Bone cement is removed from a bone cavity, such as the intramedullary canal, during a prosthetic revision. The bond 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 05:34
CPC Classifications
A; A61; A61B; A61B17/00; A61B17/16; A61B17/1613; A61B17/1628; A61B17/1604; A61B17/56; A61B17/58; A61B17/88; A61B17/8802; A61B17/8847; A61B18/00; A61B18/04; A61B18/08; A61B18/082; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/46; A61F2002/465
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
255 words
A surgical instrument for use in removing bone cement from a bone cavity, comprising: an elongated shaft of sufficient length to extend far enough into the bone cavity to mold bone cement forming a wall of the cavity, a bone cement removal tool on a working end of the shaft for use in removing bone cement form the wall of the bone cavity, a heating element carried by the shaft for transferring heat from the shaft to the bone cement removal tool for heating the tool to a temperature within a range of temperatures sufficient to plasticize the bone cement and thereby deform and weaken it upon direct contact with the heated bone cement removal tool, and at least one tangential point protection member affixed to and integral with the shaft and in heat transfer communication with the shaft, the tangential point protection member projecting laterally away from an exterior side wall of the shaft adjacent the bone cement removal tool, the tangential point protection member having an exterior wall surface that converges to an outermost peripheral edge that produces point contact when the member is moved into engagement with the wall of a surrounding bone cavity, so that lateral movement of the heated shaft toward the bone wall will cause the outermost peripheral edge of the tangential point protection member to preferentially contact the bone wall to prevent direct contact of the bone wall with the heated shaft sufficiently to prevent damaging heat transfer from the heated shaft to the wall of the bone.
Claim 2
Dependent Claim
255 words
A surgical instrument for use in removing bone cement from a bone cavity, comprising: an elongated shaft of sufficient length to extend far enough into the bone cavity to mold bone cement forming a wall of the cavity, a bone cement removal tool on a working end of the shaft for use in removing bone cement form the wall of the bone cavity, a heating element carried by the shaft for transferring heat from the shaft to the bone cement removal tool for heating the tool to a temperature within a range of temperatures sufficient to plasticize the bone cement and thereby deform and weaken it upon direct contact with the heated bone cement removal tool, and at least one tangential point protection member affixed to and integral with the shaft and in heat transfer communication with the shaft, the tangential point protection member projecting laterally away from an exterior side wall of the shaft adjacent the bone cement removal tool, the tangential point protection member having an exterior wall surface that converges to an outermost peripheral edge that produces point contact when the member is moved into engagement with the wall of a surrounding bone cavity, so that lateral movement of the heated shaft toward the bone wall will cause the outermost peripheral edge of the tangential point protection member to preferentially contact the bone wall to prevent direct contact of the bone wall with the heated shaft sufficiently to prevent damaging heat transfer from the heated shaft to the wall of the bone.
Claim 3
Dependent Claim
21 words
Apparatus according to claim 1 in which the shaft has a great insulating handle at an end opposite from the chisel.
Claim 4
Dependent Claim
23 words
Apparatus according to claim 1 including electrical conductors within the shaft extending remotely from the shaft for connection to an electrical power source.
Claim 5
Dependent Claim
36 words
Apparatus according to claim 3 in which the elongated shaft and electrical conductors form a common coaxial unit, the outer portion being the elongated shaft and one conductor inside the insulated portion being the other conductor.
Claim 6
Dependent Claim
23 words
Apparatus according to claim 1 in which the elongated shaft is bent into a shape conforming to the contour of the medullary canal.
Claim 7
Dependent Claim
22 words
Apparatus according to claim 1 in which the elongated shaft has a heat barrier to prevent heat from dissipating up the shaft.
Claim 8
Dependent Claim
30 words
Apparatus according to claim 1 in which the bone cement removal tool comprises a bone cement removal chisel having a base and an elongated narrow tip projecting from the base.
Claim 9
Dependent Claim
20 words
Apparatus according to claim 7 in which the tip of the chisel provides thermal point contact with the bone cement.
Claim 10
Dependent Claim
29 words
Apparatus according to claim 7 in which linear motion of the chisel end in direct contact with the bone cement deforms and furrows a groove in the bone cement.
Claim 11
Dependent Claim
26 words
Apparatus according to claim 1 in which the instrument comprises a plurality of said tangential point protection members encircling the shaft at axially spaced apart locations.
Claim 12
Dependent Claim
14 words
Apparatus according to claim 10 in which said members have pointed outer edge surfaces.
Claim 13
Dependent Claim
29 words
Apparatus according to claim 11 in which said members comprise separate axially spaced apart rings projecting from the shaft of the instrument adjacent the heated tip of the instrument.
Claim 14
Dependent Claim
17 words
Apparatus according to claim 1 in which the instrument includes internal and external battery powered heating elements.
Claim 15
Dependent Claim
16 words
Apparatus according to claim 1 in which the heating elements are of less than 24 volts.
Claim 16
Dependent Claim
32 words
Apparatus according to claim 1 in which the bone cement removal tool comprises a rotary drill and in which the tangential protection member rotates on the shaft with rotation of the drill.
Claim 17
Dependent Claim
23 words
Apparatus according to claim 1 in which the heating element heats the bone cement tool to a temperature above at least 400° C.
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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) | 1994-11-11 | 1995-05-13 | 1995-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-11 | 1999-05-13 | 1999-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-11 | 2003-05-13 | 2003-11-12 | $7700.00 | Window Closed / Lapsed |