Thread Types & Specifications FAQ
Q1. What types of threads are available?
The verified product range includes eight design families: mono (smooth), screw, cog (barbed), tornado, mesh, multi, fishbone and double-needle. These names describe the thread architecture or delivery configuration, not a universal clinical indication.
For practical identification:
- Mono: smooth, barb-free thread
- Screw / tornado: spiral or helically wound construction
- Cog: thread with barbs or projections for tissue anchoring
- Mesh / multi: multi-filament or mesh-style constructions listed in the catalog
- Fishbone: a barbed configuration with a fishbone-style profile
- Double-needle: a product configuration using two needles
The exact gauge, length, USP designation, needle/cannula and pack quantity depend on the SKU. Do not infer a product’s full specification from the family name alone; read the product label, catalog entry and IFU.
Q2. What is the practical difference between mono, screw and cog threads?
The practical difference is the thread architecture and its intended function:
- Mono (smooth): no barbs and no mechanical tissue repositioning; generally used for skin-quality and collagen-related work.
- Cog (barbed): angled barbs or projections anchor in tissue and provide mechanical lifting along the direction of pull.
- Screw / tornado: one or more filaments arranged in a spiral construction to increase local tissue contact and provide localized support.
A smooth mono thread and a barbed cog thread are therefore not interchangeable, even when they use the same base material. The previous PDO Threads FAQ explains the material-level behavior; this page explains how to identify the design and specification.
Q3. How do I read thread gauge, length and USP size?
A code such as 21G × 60 mm normally identifies a 21G needle or cannula with a 60 mm needle/cannula length. Gauge refers to the outer diameter of the delivery needle or cannula: the smaller the gauge number, the thicker the delivery component. For example, 30G is finer than 27G, and 27G is finer than 26G.
USP size is different. It is a suture-diameter classification printed on some thread labels. The G in 21G is the needle/cannula gauge; it is not the USP size, and the two systems should not be converted without the product’s own table.
Within the currently verified catalog range:
| Specification | Verified range or example |
|---|---|
| Needle/cannula gauge | 18G–30G |
| Needle length | Approximately 13–140 mm |
| Thread length | Approximately 13–400 mm |
| Mono example | 30G × 13 mm |
| Mono Screw example | 29G × 50 mm |
| Cog 4D example | 21G × 90 mm |
| Eye Thread example | 30G × 25/38 mm |
| Nose Thread example | 19G L cannula, USP 2 |
The catalog also maps USP designations by verified line, including USP 6-0/7-0 on mono and screw lines, USP 2 on cog and nose lines, and USP 3 on fishbone. These are verified catalog examples, not universal rules for every SKU.
Q4. What is the difference between a sharp needle and a blunt cannula?
A sharp needle pierces the skin directly. A blunt cannula requires a small entry point first and then passes through the tissue plane with a rounded tip. The appropriate delivery format is a procedural decision for the trained practitioner, based on the technique, treatment area and product design.
The verified catalog includes examples such as an Eye Thread with a 30G W cannula / USP 7-0 and a Nose Thread with a 19G L cannula / USP 2. W and L are catalog codes; their exact meanings should not be inferred unless the product documentation defines them. Always match the needle or cannula format to the exact SKU ordered.
Q5. How many threads are in a pack or box?
Pack counts vary by SKU — there is no single standard. Current product documentation shows options of 10, 20, 50 and 100 threads per pack across different lines [7], so check the product page for the exact count and verify the unit quantity on the label when you receive an order.
Q6. Are the threads supplied sterile and for single use?
Whether a specific product is supplied sterile and single-use is stated on its label, instructions for use (IFU) and certificates. Product documentation describes ethylene oxide (EO/EtO) sterilization, individually sealed pouches, and warnings such as "Do Not Resterilize or Reuse" and "Do Not Use If Pack Is Damaged" [4][5]. Treat sterilization claims as product-specific: confirm the sterilization method, certificate and labeling for the exact SKU you are ordering rather than assuming one policy applies to everything.
Q7. How should threads be stored and how long is the shelf life?
Store unopened pouches in a cool, dry place away from direct sunlight. The exact temperature range and shelf life are printed on each product's label and IFU — do not use a thread if it is past its expiry date or if the sterile barrier is opened, torn, punctured or wet, because sterility can no longer be guaranteed [4]. As published site guidance, a shelf life of 3–5 years and a storage range of 5–25°C have been referenced for this product family; treat these as general guidance and follow the label for the specific SKU.
References
- GLPbase — PDO Threads: The Complete Guide — https://glpbase.com/pdo-threads/
- StatPearls (NCBI Bookshelf) — Sutures and Needles — https://www.ncbi.nlm.nih.gov/books/NBK539891/
- eCFR — 21 CFR 878.4840, Absorbable polydioxanone surgical suture — https://www.ecfr.gov/current/title-21/chapter-I/subchapter-H/part-878/subpart-E/section-878.4840
- ISO 11135:2014 — Sterilization of health-care products — Ethylene oxide — https://www.iso.org/standard/56137.html
- ISO 6009:2016 — Hypodermic needles for single use — Colour coding for identification — https://www.iso.org/standard/63277.html
- pdosupplies — PDO thread product documentation (catalog and product pages) — https://pdosupplies.com/collections/pdo-all-protects