CLIPSThe present invention relates to clips.
Ligature clips have been used to clamp blood and other vessels. Such clips can be either of the temporary variety, allowing their removal after surgical procedures or the permanent variety where they are left in place after the operation.
The problem with the permanent variety of clips is that they are subjected to a certain amount of buffeting within the patient and become loose or unfastened. Also in cases where the clip is used to clamp the end portion of a severed vessel, pressures within the vessel may drive the clip along the vessel until the clip becomes detached from the vessel. In either case the result for the patient is often fatal.
It is an object of this invention to provide an improved clip.
According to the invention there is provided a clip comprising a pair of rigid arms linked end to end by a flexible strip forming a hinge, and the opposite end portions of the arms supporting a locking mechanism in the form of an opening in one arm having an inwardly projecting flange and a cooperating pin projecting from the other arm, the interaction between the pin and flange being such that movement of the pin into opening encounters substantially less resistance than movement of the pin out of the opening.
A ligature clip embodying the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which:Figure 1 is a side elevation of the clip with the clip open and receiving a blood vessel;Figure 2 is a front elevation of the clip ofFigure 1;Figure 3 is a side elevation of the clip of Figure 1 closed and clamping a blood vessel;Figure 4 is a front elevation of the clip ofFigure 3; andFigure 5 is a fragmentary plan view to an enlarged scale of the end portion of the lower arm of the clip.
The clip to be described is arranged to permanently clamp a blood vessel 11.
The clip shown in Figure 1 comprises two arms 2 and 4 each of generally rectangular cross section interconnected at one end by a thin strip 6 of the same material. The arms and strip may be produced by stamping a rectangular blank of titanium. This will be described in more detail hereinafter.
The upper arm 2 carries on an internal face, adjacent its free end, a locking pin 8. The lower arm 4 has a free end portion 10 of reduced thickness, and has a central aperture 12 (see Figure 5). Projecting inwardly of the aperture 12 is an interrupted annular flange 14.
The pin 8 is arranged to engage the aperture 12 when the two arms 8 and 10 are made to close on one another. The internal diameter of the flange 14 is substantially smaller than the external diameter of the pin 8 so that when the pin 8 engages the flange 14 the interrupted portions of the flange are deflected away from the pin 8 (see Figure 4). Any attempt to withdraw the pin 8 from the aperture 12 subjects the interrupted portions to compression and so it becomes difficult if not impossible to withdraw the pin. Advantageously the ratio of the internal diameter of the flange (when undistorted) to the external diameter of the pin lies in the range of from 3:6 to 5:6 but is preferably 4:6.
It will be appreciated that the hinge 6 constrains the movement of the two arms towards one another so that the pin 8 will always be aligned with the aperture 12 at the instant of engagement to ensure engagement with the aperture upon closure. The longitudinal axis of the pin 8 is curved so that it is coincident with a circle centred on the pivotal axis formed by the strip 6 and having a radius equal to the distance of the pin 8 from the strip 6.
The length of the strip 6 is such as to ensure a minimum spacing between the two arms 2 and 4 adjacent the strip. The spacing is preferably equal to the thickness of the blood vessel when clamped to a degree sufficient to inhibit the passage of fluid through the vessel but not so great as to damage the vessel. Assuming the width of the vessel to be slightly less than the length of the arms 2 and 4 (see Figure 3) in practice this means that the ratio of the length of the strip 6 to the length of the arm 4 is in the range of from 1:4 to 1:6 but is preferably in the ratio of 1:5.
Ideally when a vessel is clamped the facing surfaces of the two arms 2 and 4 should be parallel. The cooperating surfaces of the arms 2 and 4 are planar.
Extending flush with the inner face of the arm 2 is a flange 2A and 2B projecting from each lateral side of the arm. Each flange is profiled to form a row of sharp teeth projecting away from the lateral side of the arm 2.
Extending flush with the inner face of the arm 4 is a flange 4A and 4B projecting from each lateral side of the arm. Each flange is profiled to form a row of sharp teeth projecting away from the lateral side of the arm 4.
The teeth act to prevent the clip from sliding along the blood vessel 11. As shown in Figure 4 when the blood vessel 11 is clamped by the clip the sections of the blood vessel on opposite sides of the clip diverge either because of pressure in that section of the vessel or because of the natural resilience of the vessel. Any displacement of the clip relative to the vessel will cause the teeth to engage or penetrate the adjoining blood vessel wall and this will then inhibit further displacement of the vessel.
With the clip described it will be appreciated that under normal clamping conditions the clamping action is sufficient to inhibit blood flow but not severe enough to damage the vessel, unless and until severe conditions prevail which might otherwise cause slippage of the clip along the vessel.
The clip can be fabricated of plastics but the preferred material is titanium or a titanium alloy.
Because titanium is relatively malleable the clip can be readily manufactured by the following method.
A blank is cut from a sheet of titanium. The blank is then stamped to produce the profile of the two arms and the thinned area of the strip 6. The profile of the stamping machine is such that the two halves of the stamping die allow excess metal to escape in the area of the aperture 12 and from opposite sides of the arms as flashing. This flashing is then subjected to a further stamping operation to form the interrupted flange 14 and the toothed flanges 2A, 2B, 4A and 4B.
The pin 8 is secured to the arm 2 either by force fitting it into an opening (not shown) provided, or by diffusion bonding. Instead, the pin may be partly cut out of the material of the blank and then bent into the required altitude. The arm and the pin are then clamped in a jig and the pin 8 bent to the correct curvature.
In a modification the toothed flanges 2A, 2B, 4A & 4B are curved slightly inwardly to ensure a more positive engagement with the blood vessel 11 when the clip starts to be displaced with respect to the vessel.
The arms 2 and 4 are relatively thick so that any risk of them being bent or bending in use is inhibited.
The clip can be closed on the vessel by hand or by a pair of surgical pliers.
While the clip is intended as a permanent fixture once in place it is possible to remove the clip by cutting through the strip 6 and levering the two arms apart. However this destroys the clip.
In a modification instead of the locking mechanism being in the form of an interrupted flange and a smooth pin it can take the form of a plain flange and a barbed pin. Other permanent locking mechanisms can be used. The clip can be used in applications other than in surgery for example for clamping engineering hose pipes.