Surgery – Instruments – Orthopedic instrumentation
Patent
1999-04-29
2000-12-19
Buiz, Michael
Surgery
Instruments
Orthopedic instrumentation
606 85, 407 30, 408127, A61B 1716
Patent
active
061622273
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a bone milling tool for precise preparation of.
BACKGROUND OF THE INVENTION
From the DE-OS 27 48 452 is known a bone milling tool for round milling a hip joint head which is provided with a central hole into which a centering pin is inserted. The milling head is joined to a driveshaft which is,. at least near the area of the milling head, of tubular design.
Also known is a bone milling tool as illustrated in FIG. 4. A bone milling tool of this type is used for precisely fitting preparation of bones, in particular tubular bones. It is important, in particular with cementfree implantation of prosthesis, to create an extremely precisely fitting bone bed to accommodate the prosthesis, on the one hand to ensure the largest possible contact surface for fast grafting of the bone and on the other hand to eliminate micro movements. Rotary instruments are preferred as the precision of oscillating saws is insufficient.
Bone milling tool 10a illustrated in FIG. 4 is a front-end milling tool. It is composed of a cylindrical milling head 12a with cutting teeth configured at the front. A guide pin 30 is also arranged at this side. A driveshaft 14' is mounted to the rear of milling head 12a. When using this bone milling tool 10a, guide pin 30 is pushed into a guide bore which has been entered into the bone, thus ensuring guided and directionally stable processing. Exerting pressure (see arrows 26 in FIG. 4) onto driveshaft 14' in the direction of guide pin 30 establishes contact of front-end cutting teeth with the bone and mills a rotary-symmetrical surface into the depth.
The problem with both of the aforedescribed bone milling tools lies with the respective driveshaft, which protrudes from the field of operation and has to be connected to a drive unit. If the field of operation is small and access has to be of narrow design for anatomical or surgical reasons, then it can happen that, whilst milling downwards, the driveshaft is forced out of its direction by protrusions in the field of operation, which results in a directionally unstable or directionally incorrect milling surface. The result is an inaccurate bone bed, both relative to the contact surface and relative to positioning of a prosthesis.
SUMMARY OF THE INVENTION
It is an object of the invention to create a bore milling tool which makes it easily possible to establish a bone bed of maximum fitting accuracy even in the event of a small field of operation.
An aspect of the invention involves a bone milling tool for precise preparation of bones. The bone milling tool includes a milling head connected to a driveshaft. The driveshaft simultaneously serves as a guide element which is guided in a bone. The bone milling tool further includes a toothing which is arranged on the milling head facing the driveshaft.
According to the invention, the driveshaft simultaneously serves as guide element and is passed through a continuous guide bore which is established in the bone. As the toothing is arranged at the side of the driveshaft on the milling head, work is, in contrast to conventional bone milling tools, no longer carried out by pushing but by pulling.
When using the bone milling tool, the driveshaft extends from the milling head in the direction of the bone and through the guide bore which has been established in the latter. The driveshaft then no longer protrudes from the field of operation and can no longer be forced out of its direction by objects which protrude into the field of operation. This ensures production of a bone bed of high fitting accuracy.
The driveshaft is preferably of flexible design. The use of a flexible driveshaft is only made possible because work is no longer carried out by pushing but by pulling.
According to a further advantageous embodiment, a guide pipe is inserted into the guide bore which has been established in the bone. The driveshaft then no longer rubs against the bone or adjacent soft parts. The guide pipe can be pushed thereinto from the end of the bore located opposite the fie
REFERENCES:
patent: 2753618 (1956-07-01), Stanziale
patent: 4946461 (1990-08-01), Fischer
patent: 5601561 (1997-02-01), Terry et al.
Eckhardt Harald
Krause Gero
Buiz Michael
Plus Endoprothetik AG
Woo Julian W.
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