1. Equipment for removing bone cement from bone cavities, comprising an elongated body, hollow inside, that can be inserted inside a cement-filled bone cavity, and at least one extraction rod for extracting said elongated body buried in the cement, that can be inserted inside said elongated body, wherein said elongated body comprises a plurality of rigid elements aligned with each other and associated to one another by the interposition of spacer elements, substantially tubular in shape and coaxial to said elongated body, said rigid elements each including removable means for connecting to said extraction rod which are arranged inside said elongated body, and said spacer elements are comprised of one of an acrylic resin and a bone cement,
wherein at least one of said rigid elements comprises at least one protrusion, protruding crossways to an axis of said elongated body, on which an edge of a distal end of one of said spacer elements at least partially rests, wherein said crossways protrusion comprises a discoidal body, substantially coaxial to said elongated body.
2. The equipment of claim 1, wherein said rigid elements are associated with said spacer elements by interposing a temporary fit-in type coupling.
3. The equipment of claim 2, wherein said temporary fit-in type coupling is suitable for connecting said rigid elements and said spacer elements as long as there is no axial separation force exerted between them of an established extent.
4. The equipment of claim 1, wherein at least one of said rigid elements comprises at least one connecting link, substantially tubular in shape, which can be fitted to said spacer elements.
5. The equipment of claim 4, wherein each connecting link can be fitted inside said spacer elements.
6. The equipment of claim 4, wherein at least one of said rigid elements features a pair of said at least one connecting link positioned at opposite axial ends.
7. The equipment of claim 4, wherein the rigid element arranged at a distal end of said elongated body features just one of said at least one connecting link.
8. The equipment of claim 1, wherein the rigid element arranged at a distal end of said elongated body features a closed bottom wall.
9. The equipment of claim 8, wherein an outer surface of said closed bottom wall is substantially pointed.
10. The equipment of claim 8, wherein an outer surface of said closed bottom wall is substantially conical in shape.
11. The equipment of claim 1, wherein said elongated body comprises attaching means to the cement.
12. The equipment of claim 11, wherein said attaching means is of the adhesive type.
13. The equipment of claim 11, wherein said attaching means comprises said spacer elements being made of a material that adheres to said cement.
14. The equipment of claim 13, wherein said material comprises polymethylacrylate.
15. The equipment of claim 1, wherein said means for connecting is of the threaded type.
16. The equipment of claim 15, wherein said means for connecting comprises an internal screw thread which is formed in said rigid elements and able to be engaged by a thread at least formed on at least a distal end of said extraction rod.
17. The equipment of claim 16, wherein said internal screw threads are substantially coaxial to said elongated body.
18. The equipment of claim 16, wherein a length of said thread is substantially less than a distance between at least two consecutive of said internal screw threads.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A failure resistant method of operating a plurality of computers each with their corresponding independent local memory, each substantially simultaneously operating a corresponding portion of an application program written to execute on only a single computer, and each being connected via a communications network to permit updating of corresponding memory locations, said method comprising the steps of:
(i) categorizing the memory locations of said local memories into a first reachability category in which the local memory locations are replicated in selected ones, or all, of said computers and therefore require updating via said communications network with changes to corresponding memory locations of the other computers to maintain substantial memory coherence, and into a second category in which the local memory locations are present only in the local computer and therefore no updating is required,
(ii) detecting failure of any one of said multiple computers, and
(iii) modifying said first category to remove therefrom, if present, any reference to the failed computer,
whereby no attempt is made to update any first category locations of said failed computer.
2. The method as claimed in claim 1 including the further step of,
(iv) maintaining data regarding said memory locations categorization in a reachability table.
3. The method as claimed in claim 2 including the further step of:
(v) maintaining a single said reachability table on a server computer not forming one of said multiple computers and connected thereto via said communications network.
4. The method as claimed in claim 2 including the further step of:
(vi) maintaining a multiplicity of reachability tables, each on a corresponding one of said multiple computers.
5. The method as claimed in claim 1 including the further step of,
(vii) detecting failure by at least one of the group of failure detection modes consisting of power supply failure, communication link failure, failure to respond to interrogation, and failure to regularly report as expected.
6. The method as claimed in claim 1 wherein said memory locations include an asset, structure or resource.
7. A computer program product comprising a set of program instructions stored in a storage medium and operable to permit a plurality of computers to carry out the method claimed in claim 1.
8. A multiplicity of computers interconnected via a communications network and operable to ensure carrying out of the method as claimed in claim 1.
9. A failure resistant multiple computer system in which a plurality of computers each has a corresponding independent local memory, each simultaneously operates a corresponding portion of an application program written to be executed only on a single computer, and each is connected via a communications network to permit updating of corresponding memory locations, said system including a reachability means to categorize memory locations of said local memories into a first category in which the local memory locations are replicated in selected ones, or all, of said computers and therefore require updating via said communications network with changes to corresponding memory locations of other computers, to maintain substantial memory coherence, and into a second category in which the local memory locations are present only in the local computer and therefore no updating is required, and wherein said system further includes a failure detection means connected to each said computer to detect failure of any one of said multiple computers, and a reachability modifier connected to said failure connection means and to said reachability means to modify said reachability means by modifying said first category to remove therefrom, if present, any reference by the failed computer whereby no attempt is made to update any first category memory locations of said failed computer.
10. The system as claimed in claim 9 wherein said reachability means comprises a reachability table in which is maintained data regarding said memory location classification.
11. The system as claimed in claim 10 and including a server computer connected to said communications network, said server computer including a single reachability table.
12. The system as claimed in claim 10 wherein each of said multiple computers includes a corresponding reachability table.
13. The system as claimed in claim 9 wherein said failure detection means is selected from the group consisting of power supply failure detectors, communication link failure detectors, interrogation response failure detectors, and regular reporting failure detectors.
14. The system as claimed in claim 9 wherein said memory locations include an asset, structure or resource.
15. A single computer adapted to co-operate with at least one other computer in order to carry out the method as claimed in claim 1 or form the computer system as claimed in claim 9.