Surgery – Instruments – Orthopedic instrumentation
Patent
1990-02-08
1990-12-18
Hafer, Robert A.
Surgery
Instruments
Orthopedic instrumentation
606 59, 606105, A61F 504
Patent
active
049783483
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates generally to medical engineering applied in orthopedics and traumatology and more specifically to compression-distraction apparatus for osteosnnthesis.
PRIOR ART
Known in the present state of the art is an externally applied device for orthopedic axial fixation (FR, A, No. 2,559,380), comprising a metallic rod shaped as a parallelepiped carrying two pin clamps. The jaws of the pin clamp are held by a screw, and one of the jaws is longitudinally traversable by virtue of a threaded spindle.
The aforediscussed device enables one to fix tubular bones and carry out longitudinal motion of bone fragments. However, parallel-arranged cantilevered pins are liable to slip off the bone under the effect of a load applied thereto. Besides, the slots made in the clamps and adapted to receive the pins are spaced somewhat apart from one another which is far from being always admissible for a given bone segment.
One prior-art orthopedic apparatus is made use of for treatment of bone lesions, intended for external axial fixation of the injured bone or framents of bone fractures within a wide range of adjustment (GB,A, No. 2,168,255).
The apparatus features a central body made up of three or more components which are movable with respect to one another due to telescopic sliding over each other without a possibility of relative rotation. The body components are provided with an interlocking means which can be actuated independently for each pair of the components.
Moreover, there is provided a power cylinder having at least three elements adapted to be screwed into one another and to move lengthwise a common axis when one of the elements is set in rotation. The elements are situated at the cylinder end and have pins engageable with the eccentric spaces of the cylindrical body.
The apparatus described above is capable of controlline the arrangement of the elements provided with pins, both with respect to one another and to the central body. However, the pins are mounted in the holes of the elements at a definite distance from one another and are therefore inconvenient for use due to impossibility of free selection of the place of installation of the rods in the bone involved. Besides, no provision is made in the orthopedic apparatus for external axial fixation for a possibility of adjusting the angle at which the pins are arranged in the element; furthermore the pins are guided in the dorsipalmar direction which is causative of inujury to the wrist flexor muscles.
For treatment of injuries to the wrist joints use is made of a dynamometric external retainer (GB,A, No. 2,146,533) having two oblong supports, each carrying fixing pins. Both of the supports are interconnected through a universal joint which comprises a number of elements for adjusting the degree of displacement of the distal support with respect to the proximal support. The latter support has a number of holes for receiving the fixing pins and the respective threaded locking elements. The distal support has a plunger to adjust the length of the support. A setting screw adapted to reciprocate in the slot of the distal suppoty is for adjusting the degree of the plunger extension. The dynamometric external retainer discussed above makes it possible to fix the joint of two adjacent bones lengthwise the lateral carpal surface.
Provision is made in the aforesaid retainer for a possibility of adjusting the degree of displacement of the sital support with respect to the proximal one and measuring the displacement length. Apart from that, the pins of the distal support are movable with respect to those of the proximal support. However, the holes for the pins in the retainer supports are spaced a definite specified distance from one another. No provision is made for setting and locking the pins at different angles to the longitudinal axis of the retainer supports. The pins are arranged in the same plane parallel to the longitudinal bone axis. In additional there are greatly impeded the application of the dynamometric external r
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Klinik fur Orthopadische Chirurgie der Universitat Bern, Schweiz, Roland P. Jakob, "Der Kleine Fixateur Externe".
Brown Michael
Hafer Robert A.
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