Surgery – Instruments – Orthopedic instrumentation
Patent
1994-10-13
1997-01-14
Tucker, Guy V.
Surgery
Instruments
Orthopedic instrumentation
606 69, 606 73, A61B 1770
Patent
active
055934072
DESCRIPTION:
BRIEF SUMMARY
This is a 35 U.S.C. 371 application based on PCT/GB92/01957, filed Oct. 26, 1992.
FIELD OF THE INVENTION
This invention relates to internal ilio-lumbar fixation. Fixing of the ilium to the lower lumbar vertebrae may be required for (a) various diseases of the vertebral column; or (b) fractures and/or dislocations of the sacro-iliac joint region resulting in an unstable hemi-pelvis; this fixation being necessary to indirectly immobilise the lumbo-sacral segment whilst fusion is taking place after a bone graft, to stabilise an unstable lumbo-sacral spine due to fracture or disease, to reduce and correct a deformity of the spine, or to reduce and immobilise a sacro-iliac region fracture or dislocation until healing has taken place.
BACKGROUND OF THE INVENTION
In the past, ilio-lumbar fixation has been attempted by (a) the Magerl method in which external fixator pins are applied from behind to transfix the posterior mass of each ilium and other pins transfix the pedicles of a lumbar vertebrae, these fixators then being connected by an external frame, but this method has a very limited application and has not been generally adopted; (b) the Galveston method in which rods affixed to the spine by various means are passed through or into the posterior iliac mass from medial to lateral, being used mainly for very extensive corrections of spinal deformity when there is a need to fix the lumbo-sacral segment, affording limited stability to this segment in the saggital plane but only very poor stability in the coronal plane and rotation.
Many methods also exist that attempt to achieve direct lumbo-sacral fixation, i.e. between the lowest lumbar vertebrae and the sacrum, all of which use some form of screw fixation into the sacrum itself, but there is a danger of damaging nerves in or exiting from the sacrum, and the poor mechanical quality of sacral bone makes the strength of the screw fixation to the sacrum unpredictable.
SUMMARY OF THE INVENTION
The present invention achieves an indirect lumbo-sacral fixation making use of intact powerful ligaments joining the ilium to the sacrum.
According to one aspect of the present invention, for use when there is no structural disruption and the sacro-iliac ligaments are intact, an internal ilio-lumbar fixation comprises at least one pedicle screw of the tulip type, a pelvic plate (preferably curved to match an iliac crest formation), and a bent rod having a spinal portion for engagement in the bifurcated head of the pedicle screw and a pelvic portion for engagement with the pelvic plate; in which combination: spinal portion of the bent rod and to be pressed into firm engagement therewith by the usual grubscrew screwing into the bifurcated head, and at least one additional locking screw in a screwthreaded hole through one side of the head to engage the spinal portion of the bent rod; having a non-circular female cross-section, and a locking screw in a screwthreaded hole opening into at least one side of the female hole; its pelvic portion affording a close sliding fit in the female hole in the pelvic plate.
In use, the bifurcated tulip type pedicle screw is screwed into a hole in one pedicle of the lowest lumbar vertebra, the spinal portion of the bent rod is fitted into the bifurcated head of the pedicle screw with the pelvic portion projecting through a notch in the adjacent ilium and projecting up to or beyond the posterior face of that ilium, the pelvic plate is engaged with the pelvic portion of the bent rod by fitting of the female hole on to the part of the bent rod having a mating male cross-section and, with the pelvic plate extending over the posterior face of the ilium, the pelvic plate is secured to the ilium by bone screws. The washer is fitted into the bifurcated head of the pedicle screw and pressed into firm engagement with the spinal portion of the bent rod by screwing the usual grubscrew into the bifurcated head, and the locking screw in the pelvic plate and the additional locking screw in the pedicle screw are screwed in tight against the pelvic port
REFERENCES:
patent: 3242922 (1966-03-01), Thomas
patent: 4773402 (1988-09-01), Asher et al.
patent: 4887595 (1989-12-01), Heinig et al.
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