Surgery – Instruments – Orthopedic instrumentation
Patent
1991-03-04
1993-05-18
Hafer, Robert A.
Surgery
Instruments
Orthopedic instrumentation
606 86, 606 79, A61B 1700
Patent
active
052116450
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for guiding an internal saw for long tubular bone osteotomy.
It is already known to cut through tubular bones from the outside, through the periosteum or from the inside, outwards from the medullary cavity, for example if the tubular bones have to be lengthened or shortened or if bone segment displacements are required.
As a rule, external osteotomy is carried out with an oscillating saw (DE-AS 1491219). Once the bone has been exposed, first the periosteum and then the substantia corticalis mentioned cortex in the following are cut through. This cutting through of the periosteum which supplies the bone's vital needs and which is rich in blood vessels, can result in vitality disorders during the recovery process.
With regard to the osteotomy outwards from the drilled out medullary cavity, in other words from the interior, the periosteal tube enclosing the tubular bone remains largely unharmed, so that vitality disorders in the region of the parting line through the bone are not anticipated.
Osteotomy from the medullary cavity is a particularly good idea if medullary nailing is involved. The access path for introduction of the medullary nail is in this case the same that is used for introduction of the internal saw, so that in the region of the osteotomy, not only the periosteal sheath but also the soft parts are intact.
In the case of osteotomy from within, a circular saw blade is used which is seated on a central arbor which is usually rotated by a compressed air drive. The arbor is guided by a guidance system which, with a slight bending action, presses the saw blade against the cortex from within (DE-AS 1288241). Since the axis of rotation of the saw blade and the axis of rotation of the guide system are inclined at an angle, there is a marked axial loading on the saw blade so that it assumes an umbrella shape. Consequently, it is no longer possible to make a clean saw cut. It has been found that the cuts made with the known guide systems are not closed but become helical and blurred.
The problem on which the invention is based therefore resides in so developing the device for guiding an internal saw for the osteotomy of long tubular bones that it is possible to achieve an exact and circular cut through the cortex from inside the medullary cavity at any desired location along a tubular bone without any substantial damage to the periosteum.
This problem is resolved by an elongate stem, by a mandrel which projects centrally from one end of the stem and in the peripheral surface of which there is recessed a longitudinal groove parallel with its axis and which continues in the stem and through the stem in a longitudinal recess which is orientated in alignment with the groove, and by a spacer sleeve adapted to be longitudinally displaced and fixed on the mandrel.
Ideally, the longitudinal groove is at least at the bottom provided with a circular cross-section, the radius of which corresponds to the longitudinal recess in the stem which is formed by an eccentric bore. So that the saw blade can saw into the cortex to its maximum depth, the depth of the longitudinal groove corresponds to the diameter of the bore or to the shaft which is guided in it.
The stem may be cylindrical in construction and may extend coaxially with the mandrel.
The saw blade with its central arbor is introduced into the drilled out medullary cavity as far as the intended osteotomy site. Then, the arbor is inserted into the longitudinal groove in the mandrel and through the bore in the stem, the saw being driven and in its position, sawing into the cortex, the final position of the device in relation to the tubular bone being determined by the previously corresponding displaced and fixed spacer sleeve. Then the device is rotated guaranteeing a perfect radial guidance of the saw blade. By means of the device according to the invention, therefore, the arbor of the internal saw which is initially displaced centrally in relation to the medullary cavity is displaced radially outwardly in the medullary cavity a
REFERENCES:
patent: 3214869 (1965-11-01), Stryker
patent: 3472229 (1969-10-01), Kuntscher
patent: 3867932 (1975-02-01), Huene
patent: 3892232 (1975-07-01), Neufeld
patent: 4273117 (1981-06-01), Neuhauser
patent: 4341206 (1982-07-01), Perret et al.
patent: 4381770 (1983-05-01), Neufeld
patent: 4697586 (1987-10-01), Gazale
New Instruments for the Operative Treatment of Fractures, 60Doy Moreira, KNY-Scheerer Corp., Apr. 1941.
International Search Report of application PCT/EP 90/01079 dated Nov. 16, 1990 (2 pages.).
Office Action relating to the German priority application P 39 21 973.9 dated Mar. 6, 1990 (2 pages.).
Baumgart Rainer
Betz Augustin
A. Earley John F.
A. Earley III John F.
Hafer Robert A.
Rimell Sam
LandOfFree
Device for guiding an internal saw for long tubular bone osteoto does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for guiding an internal saw for long tubular bone osteoto, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for guiding an internal saw for long tubular bone osteoto will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-801072