Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-07-27
2003-12-02
Robert, Eduardo C. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C623S017110
Reexamination Certificate
active
06656178
ABSTRACT:
The invention concerns improvements in and relating to vertebral-column fusion devices, surgical apparatus and surgical methods. In particular, but not exclusively, the invention relates to a vertebral-column fusion device that is suitable to be received in an intervertebral space between two dorsal vertebrae, said fusion device comprising a curved strip of biocompatible material, with the width of the strip being such that after placement said strip makes contact with the aforementioned vertebrae.
Fusion devices aim to promote fusion of the adjoining vertebrae together. As such they are distinct from disc replacements where the new disc aims to mirror the behaviour of and to be given the mobility of the natural disc it replaces.
Fusion devices, in the most general sense, are known and are employed in cases where, as a result of accident, overloading, old age or otherwise, an intervertebral disc of the dorsal vertebral column is no longer able to perform its normal supporting and stabilising function. In these cases there is fitted in the space of said intervertebral disc a device which entirely or partially takes over the load-bearing function of the intervertebral disc until bone fusion has taken place. Known fusion devices of this type are constituted by a so-called cage construction with a closed peripheral surface which, for example, may have a cylindrical shape, and two end faces which after placement make contact with the two vertebrae bounding the intervening space. This type of fusion device is introduced into the intervertebral space by means of a surgical intervention and is maneuvered into a precise position. Moreover, for good stability and satisfactory load-bearing capacity it is usually necessary to fit two of these devices in the intervertebral space, side by side, one on each side of the vertebral column.
One disadvantage of these known devices is that they are difficult to fit in the intervertebral space, fitment being effected by means of a labourious, time-consuming and therefore expensive surgical intervention, in the course of which a relatively large access opening has to be made, with destabilisation and local trauma as a consequence. In the case of a posterior approach this is effected, as a rule, on the left and/or right sides of the spinal cord and in either case results in a fairly serious intervention.
The invention has amongst its aims to provide a better device that is simpler to fit in the intervertebral space and that, while preserving the simplicity of fitting, can nevertheless have a larger and therefore more favourable bearing surface than the known devices. The invention has amongst its aims to provide advantageous surgical apparatus for introducing devices into an intervertebral space. The present invention has amongst its aims to provide an advantageous surgical method for introducing a fusion device into an intervertebral space and/or for using surgical apparatus.
According to a first aspect of the invention we provide an intervertebral fusion device, the device comprising an elongate element, the elongate element providing one or more upper load bearing surfaces and one or more lower load bearing surfaces, the upper and lower load bearing surfaces being vertically spaced from one another by the elongate element, the elongate element having a first state and a second state, the elongate element having a substantially linear configuration in the first state and a less linear configuration in the second state, the elongate element being capable of transition, at least once, from the second state to first state and being capable of transition, at least once, from the first state to the second state, the elongate element being of shape memory alloy.
Preferably the intervertebral fusion device promotes fusion of one vertebrae to an adjacent vertebrae with the device there between. Fusion may be promoted by the ingrowth of bone or other material. The fusion device may restrain movement of one vertebrae relative to the other vertebrae the fusion device contacts.
The elongate element may be a substantially planar element, for instance a strip or sheet.
The elongate element may have a non-rectilinear cross-section at one or more locations along its length. The non-rectilinear cross-section may be provided throughout the length. The non-rectilinear cross-section may be provided at a plurality of locations along the length, with a rectilinear cross-section being provided at a location between two or more of those locations, ideally between each of those non-rectilinear cross-sections. The non-rectilinear cross-section may provide an increased thickness portion at the upper edge/upper load bearing surface and/or at the lower edge/lower load bearing surface of the elongate element. The non-rectilinear cross-section may be of a linear C-shaped cross-section. The portions of the elongate element having a non-rectilinear cross-section may have the same profile in the first and second states. The portions of the elongate element between the non-rectilinear portions may flex and/or bend during the change from first to second state and/or vice-versa.
The elongate element may be a mesh. The elongate element may be continuous or may have one or more holes or apertures in it. The holes may be round and/or oval and/or triangular and/or diamond shaped.
The elongate element may have a linear upper load bearing surface or surfaces. The elongate element may have a discontinuous upper surface. One or more indentations may be provided in the upper load bearing surface. The elongate element may have a serrated upper load bearing surface or surfaces. The elongate element may have one or more protrusions or spikes provided on the upper load bearing surface or surfaces. The upper surface of the elongate element may be defined by one or more, preferably linear, load bearing surfaces interspaced by one or more indentations. The indentations may be triangular in shape. The upper load bearing surface or surfaces of the elongate element may be provided with one or more protrusions or teeth. The protrusions or teeth may have a triangular profile.
The elongate element may have a linear lower load bearing surface or surfaces. The elongate element may have a discontinuous lower surface. One or more indentations may be provided in the lower load bearing surface. The elongate element may have a serrated lower load bearing surface or surfaces. The elongate element may have one or more protrusions or spikes provided on the lower load bearing surface or surfaces. The lower surface of the elongate element may be defined by one or more, preferably linear, load bearing surfaces interspaced by one or more indentations. The indentations may be triangular in shape. The lower load bearing surface or surfaces of the elongate element may be provided with one or more protrusions or teeth. The protrusions or teeth may have a triangular profile.
The upper and lower load bearing surface and/or one or more of the upper and lower load bearing surfaces may be parallel to one another. The upper and lower load bearing surface and/or one or more of the upper and lower load bearing surfaces may be angled relative to one another. The angle between a projection of the upper load bearing surfaces and/or at least one of the upper load bearing surfaces and the lower load bearing surface and/or at least one of the lower load bearing surfaces may be 5° to 15°, more preferably 7° to 13°. More preferably the angle is 8° to 12°, still more preferably 9° to 11° and ideally is 10°. One or both of the upper or lower load bearing surfaces may be non-perpendicular to the height of the elongate element.
The upper and/or lower load bearing surface or surfaces may contact and/or enter the vertebrae in use.
The vertical spacing of the upper and lower load bearing surface or surfaces may be between 7 mm and 20 mm, preferably between 8 mm and 17 mm and ideally between 9 mm and 15 mm. The maximum vertical spacing is preferably less than 22 mm, more preferably less than 19 mm and ideally less than 17 mm. The maximum vertical
Birkbeck Alec Paul
Fenton Gary Stuart
Nijenbannin Gert
Pfleiderer Martin
Sanders Marc
Baat B.V. Engineering
Comstock David
Kunzler & Associates
Robert Eduardo C.
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