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简体中文Ligation Clips — Polymer and Titanium
A ligation clip is a small implantable device applied across a vessel or duct to occlude it, placed with an applier rather than tied. Clips are made from titanium or from a polymer, and the two families differ in material, in how the clip closes, and in how they behave under imaging.
Why it matters
A clip and a tie do the same job by different means: a ligature is knotted and a clip is applied. Because the clip is a manufactured element rather than a knot formed at the point of use, its material and its closure mechanism are specifications rather than technique. Knowing which family a clip belongs to is what explains its behaviour on later imaging — a question that arises long after the operation.
Applied, not tied
A ligature is formed at the point of use: the surgeon passes a strand around the structure and ties it, and the knot is made in the moment. A clip is manufactured, arrives complete, and is positioned and closed by an applier.
That is the whole distinction, and most of what follows from it is a consequence of the clip being a made object. Its dimensions, its closure mechanism and its material are specifications, fixed before it reaches the field, in a way that a knot never is.
Two families, two mechanisms
Titanium clips close by deformation. The applier bends the clip around the structure, and the metal holds the shape it has been bent into. There is no latch; the closure is the deformation.
Polymer clips close by locking. The clip carries a latch that engages as the jaws come together, so closure is positively retained by a mechanism rather than by the material having been permanently bent. The polymer is typically a polyacetal, and it is non-absorbable.
These are genuinely different mechanisms, not two routes to the same one, and they are the reason the two families are discussed separately rather than as variants of a single device.
Imaging behaviour is a material property
Titanium is radiopaque: it attenuates X-rays strongly and is visible on radiographs and CT. Polymers generally are not, which is why many polymer clips carry a deliberate radiopaque marker so that the clip can be located.
This difference is a property of the materials, and it is worth stating plainly because it arises long after the operation, when someone is looking at a scan and needs to know what they are seeing.
What this article will not do is turn that into a safety statement. Whether a given device is MR conditional, and under what conditions, is regulated, product-specific information that belongs in the instructions for use supplied with the product. A reference page is not the controlled document for it, and treating a general material property as though it were a device-level safety assurance is exactly the error worth avoiding.
The applier is a separate product
The clips are the implants; the applier is the instrument that places them. Appliers are single-use or reusable depending on the product, and whether a given applier is intended for a given clip is a specification stated in the instructions for use. It is not something to infer from the two being sold by the same manufacturer.
Key terminology
- Ligation
- Occluding a vessel or duct. It may be done by tying a ligature or by applying a clip; the objective is the same and the means differ.
- Applier
- The instrument that positions and closes the clip. Single-use or reusable, and separate from the clips themselves.
- Locking clip
- A polymer clip with a latch that engages when the clip is closed, so closure is positively retained by the mechanism.
- Non-locking clip
- A clip, typically metal, held closed by deformation of the material rather than by a latch.
- Deformation closure
- Closure achieved by plastically bending the clip so it stays in the closed shape. The mechanism used by titanium clips.
- Radiopacity
- The degree to which a material attenuates X-rays. Metals are radiopaque; many polymers are substantially less so.
- Imaging artefact
- Distortion in a CT or MR image produced by an implanted material. A property of the material's interaction with the imaging modality.
Technical characteristics
- Titanium clip — material
- Titanium or a titanium alloy
- Titanium clip — closure
- Deformation; the clip is bent closed and holds that shape
- Polymer clip — material
- A non-absorbable polymer, commonly a polyacetal
- Polymer clip — closure
- A locking mechanism; the latch engages when the clip is closed
- Applier
- A separate device from the clips; single-use or reusable depending on the product
- Radiopacity
- Titanium is radiopaque. Polymer clips are typically much less so, though many carry a radiopaque marker.
- Imaging artefact
- A material property that differs between the two families. Not a safety statement — see the instructions for use.
- Indications
- Stated in the instructions for use. Approved indications, and vessel size ranges, vary by product and market.
How it compares
| Family | Material | Closure mechanism | Behaviour under X-ray |
|---|---|---|---|
| Titanium clip | Titanium or titanium alloy | Deformation | Radiopaque |
| Polymer clip | Non-absorbable polymer | Locking latch | Largely radiolucent; may carry a marker |
| Suture ligature | Suture material | Knot tied at the point of use | Depends on the suture material |
What clinicians weigh when selecting
Mechanism of closure
A titanium clip is held closed by having been deformed; a polymer clip by a latch that engages. Those are different mechanisms, and each is a property of the clip rather than of the technique.
What later imaging will show
Metal is radiopaque and interacts with CT and MR differently from a polymer. The relevant question is what imaging the patient is likely to undergo, and that is a clinical judgement informed by the instructions for use.
Clip and applier are separate products
The applier positions and closes the clip; the clip is the implant. Compatibility between a given applier and a given clip is specified, not assumed.
Sizing
Clips are supplied in sizes, and the range a size is intended for is a product specification stated in the instructions for use.
Clip against ligature
A clip is applied and a ligature is tied. Both occlude; which is used is a surgical judgement about the vessel, the access and the case.
The instructions for use govern
Indications, contraindications, sizing, imaging information, warnings and precautions are stated there and vary by product and market.
Frequently asked questions
What is the difference between a polymer and a titanium clip?
The material and the closure mechanism. A titanium clip is closed by deformation — it is bent shut and holds that shape. A polymer clip closes with a locking latch that engages. They also behave differently under imaging.
Do polymer clips show up on a scan?
Polymers are generally much less radiopaque than metals, which is why many polymer clips carry a radiopaque marker. What a specific product shows is stated in its instructions for use.
Are polymer clips MRI safe?
MR safety information is product-specific and regulated, and it is stated in the instructions for use supplied with the product. We do not publish MR safety statements here — the controlled document is the only correct source.
Are ligation clips absorbable?
The clips described here are non-absorbable — both the titanium and the polymer families. Whether a given product is absorbable is stated in its instructions for use.
Can any applier be used with any clip?
No. Compatibility between an applier and a clip is a product specification stated in the instructions for use, and it is not to be assumed.
Which is better, a clip or a tie?
We do not rank them. A clip is applied and a ligature is tied; both occlude. Which is used is a surgical judgement about the vessel, the access and the case.
Instructions for use
The instructions for use supplied with the product is the controlled document for indications, contraindications, sizing, applier compatibility, MR safety and imaging information, warnings and precautions. Where this article and the instructions for use differ, the instructions for use govern. Approved indications vary by market.
Medical & regulatory notice
This article is general reference information for healthcare professionals about how ligation clips are constructed. It is not medical advice, not surgical instruction, not a recommendation for any technique, procedure or patient, and not a substitute for the instructions for use supplied with the product or for clinical judgement. It contains no MR safety statement; that information is product-specific and is stated in the instructions for use. Product availability and approved indications vary by market. Dolphin Sutures manufactures ligation clips; nothing here should be read as a claim of clinical benefit or of superiority over another product or approach.