Spinal needle abstract
A spinal needle assembly in which means are provided for bridging
the end cap of the obturator and the hub of the cannula to prevent
relative axial movement between the obturator and cannula.
Spinal needle claims
What is claimed is:
1. A spinal needle assembly in which an obturator having an end
cap extends into a cannula having a needle bevel at one end and
a hub at the opposite end for engagement with said end cap, and
means for aligning the obturator and the cannula, the improvement
comprising means for bridging said end cap and hub to prevent relative
axial movement between said obturator and cannula, said bridging
means being adapted for rapid manual removal by an operator and
comprising a molded overcap which overlies said end cap and extends
over protruding portions of said end cap and hub.
2. An assembly as described in claim 1 said end cap having a lower
rim and said hub having an upper rim with said cap overlying said
hub so that said rims are adjacent each other, said bridging means
comprising a unitary member having an upper portion and a spaced
lower portion, said upper portion being adapted for location on
said cap above said cap rim and said lower portion being adapted
for location on said hub below said hub rim and means coupling said
upper portion to said lower portion.
3. An assembly as described in claim 2 said bridging means being
formed as a molded, integral, one-piece member.
4. An assembly as described in claim 2 said bridging means further
comprising finger-engaging means for rapid removal of the unitary
member from the cap and hub.
5. An assembly as described in claim 2 said bridging means being
dimensioned so as to prevent its connection to the cap and hub unless
the obturator and cannula are properly aligned.
Spinal needle description
BACKGROUND OF THE INVENTION
This invention relates to a novel spinal needle assembly.
Typical spinal needle assemblies comprise an obturator having an
end cap, a cannula having a needle bevel at one end and a hub at
the opposite end, and a housing for the obturator and the cannula.
The obturator extends into the cannula so that the end of the obturator
opposite its end cap is substantially aligned with the bevel at
the one end of the cannula, so as to prevent coring during insertion
of the spinal needle.
Prior to or during insertion of the spinal needle, occasionally
the obturator will become disengaged from the cannula. This problem
is particularly serious with smaller diameter gauges, when the unit
is inverted by the operator. Such disengagement or backoff of the
obturator from the cannula is a serious problem and can create the
environment for potential tissue traps which can later be deposited
within the subarachnoid space, possibly resulting in the formation
of epidermoid tumors.
Typically, the spinal needle assembly utilizes a cap dink, which
serves to align the obturator cap with the cannula hub. However,
it has been found that this cap dink does not necessarily maintain
the cap and hub in proper aligned relationship, particularly when
the spinal needle assembly is inverted or tilted drastically prior
It is, therefore, an object of the present invention to provide
means for maintaining the obturator within the lumen of its mated
cannula. However, it is important that the operator have the ability
to remove the obturator quickly and smoothly. Thus, any means for
maintaining the obturator within the cannula must be easy to remove
and must enable simple, smooth and rapid removal of the obturator
with respect to the cannula.
Further, while the typical spinal needle assembly has utilized
a hub slot and cap dink for aligning the cap and hub, the slot/dink
relationship is designed as a bevel match locator, and is not intended
to be an obturator locking device.
We have discovered a system by which the obturator and the cannula
can be effectively locked in place and properly aligned during insertion,
yet the obturator can be pulled rapidly and smoothly from the cannula
once insertion has been effected.
It is, therefore, an object of the present invention to provide
a spinal needle assembly having obturator backoff prevention means.
Another object of the present invention is to provide a spinal
needle assembly in which the obturator can be removed quickly and
Other objects and advantages of the present invention will become
apparent as the description proceeds.
SUMMARY OF THE INVENTION
In accordance with the present invention, a spinal needle assembly
is provided in which an obturator having an end cap extends into
a cannula having a needle bevel at one end and a hub at the opposite
end for engagement with the cap. The assembly further has means
for aligning the obturator and the cannula.
The improvement comprises means for bridging the end cap and the
hub to prevent relative axial movement between the obturator and
the cannula. The bridging means is adapted for rapid manual removal
by an operator.
In the illustrative embodiment, the end cap has a lower rim and
the hub has an upper rim. The cap overlies the hub so that the rims
are adjacent each other. The bridging means comprises a unitary
member having an upper portion and a spaced lower portion. The upper
portion is adapted for location on the cap above the cap rim and
the lower portion is adapted for location on the hub below the hub
rim. Means couple the upper portion to the lower portion.
In the illustrative embodiment, the bridging means is formed as
a molded, integral, one-piece member and comprises a generally U-shaped
member carrying finger-engaging means for rapid removal.
A more detailed explanation of the invention is provided in the
following description and claims, and is illustrated in the accompanying
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of a spinal needle assembly constructed
in accordance with the principles of the present invention;
FIG. 2 is a front view, partially broken for clarity, of a spinal
needle constructed in accordance with the principles of the present
FIG. 2A is a fragmentary view showing the top portion thereof,
with the cap separated from the hub;
FIG. 3 is an enlarged view, taken partially in cross-section, of
the top portion of FIG. 2;
FIG. 4 is a top view, with a portion broken for clarity, of a bridging
member used in accordance with the invention;
FIG. 5 is an elevational view thereof;
FIG. 6 is an enlarged view of the top portion of a spinal needle,
illustrating a modified bridging means which could be used in accordance
with the principles of the present invention;
FIG. 7 is a cross-sectional view thereof, taken along the plane
of the line 7--7 of FIG. 6;
FIG. 8 is a view similar to the view of FIG. 6 but with the bridging
means twisted 90.degree.; and
FIG. 9 is a cross-sectional view thereof, taken along the plane
of the line 9--9 of FIG. 8.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT
Referring to the drawings, a spinal needle assembly 10 is shown
therein, in which a lower housing 12 and a cooperating upper housing
14 removably encase a spinal needle 16.
Spinal needle 16 includes a cannula 18 having a needle bevel 20
at one end and a hub 22 at its opposite end. Hub 22 has a main holding
portion 24 and an upper portion 26 carrying an upper rim 28 with
the hub defining an axial bore from its top to the needle bevel.
Inserted within the axial bore of cannula 18 and its hub 22 is
an obturator 30 comprising a stylet 32 having an obturator cap 34
connected to an end thereof. The obturator cap includes a lower
rim 36 which abuts upper rim 28 of upper hub portion 26.
The upper rim 28 defines a slot 37 which cooperates with a cap
dink 38 for aligning cap 36 properly with hub 22. When cap 34 and
hub 22 are properly aligned, the stylet 32 will be properly located
with respect to needle bevel 20. However, in certain prior art constructions
if the spinal needle assembly were tilted or tipped, the cap 34
and hub 22 would become improperly aligned, as illustrated in FIG.
2A, thereby moving stylet 32 axially with respect to the cannula.
To prevent this possible axial movement, a bridging member 40 is
provided for bridging end cap 34 and hub 22 to prevent relative
axial movement between the obturator and the cannula.
Bridging member 40 is shown in detail in FIGS. 3-5. The bridging
member has a generally U-shaped top configuration and includes an
upper portion 42 and a spaced lower portion 44 with portions 42
and 44 being coupled by wall 46. As shown most clearly in FIG. 3.
upper portion 42 has a lower surface 48 which engages the upper
surface 50 of lower rim 36 and lower portion 44 has an upper surface
50 which engages the underside of upper rim 28 thereby effectively
clamping lower rim 36 to upper rim 28. In effect, bridging member
40 acts as a clamp to maintain the cap and hub in proper alignment.
A flattened, front surface 52 of bridging member 40 is provided,
so as to enable an operator to manually remove bridging member 40
by simply placing the thumb or thumbnail against surface 52 and
pivoting the bridging member away from its connected position. Bridging
member 40 is preferably symmetrical so that the flattened, front
surface 52 can be provided on both sides to enable easy removal
by both right-handed and left handed operators.
Another manner of enabling removal of the bridging member 40 could
be gained through the use of a grooved wall section at the bight
53 of the U which would act as a hinge. In addition, a raised section
could be provided on the external surface of one or both of the
arms of the U to provide a pushing surface for removal.
It is preferred that bridging member 40 be formed of a thermoplastic
material which is molded in a unitary, one-piece, integral construction.
A modified bridging member 54 is illustrated in FIGS. 6-9. Referring
to these figures, bridging member 54 comprises a cap-like member
having a top portion 56 and circumferential downwardly depending
sidewall 58. In the position illustrated in FIG. 6 the bridging
member defines upper groove 60 and lower groove 62 which are formed
by inwardly extending members 64 and 66 and also by inwardly extending
members 68 and 70. Inwardly extending members 64 and 66 overlie
lower rim 36 of cap 34 and members 68 and 70 underlie upper rim
28 of hub 22 to thereby create a clamp with respect to lower rim
36 and upper rim 28. As shown most clearly in FIG. 7 members 64
and 66 (and likewise, members 68 and 70--not shown) are only segmental
so that when bridging member 54 is turned 90.degree., as illustrated
in FIGS. 8 and 9 these members will bypass the hub and cap which
have flattened sides 74 76. Thus removal of the bridging member
54 is simplified and merely requires a 90.degree. twist by the opertor.
It can be seen that simplified means have been provided for maintaining
the obturator within the lumen of its mated cannula. Further, the
operator has the ability to remove the obturator quickly and smoothly
once insertion of the spinal needle has been effected.
Although illustrative embodiments of the invention have been shown
and described, it is to be understood that various modifications
and substitutions may be made by those skilled in the art without
departing from the novel spirit and scope of the present invention.