Threads
5 min readMono, Cog and Screw PDO Threads: Which for What
Educational reading for licensed practitioners — not clinical or injection guidance.
Not all PDO threads do the same job. The material may be identical — polydioxanone, a long-established absorbable suture — but the geometry of the thread determines whether it lifts, tightens or simply improves skin quality. Choosing between mono, cog and screw threads is really a question of what the tissue needs: repositioning, support, or biostimulation.
The Three Thread Types
The three most commonly referenced PDO configurations behave quite differently.
Mono threads
Mono threads are smooth, single filaments with no barbs. They do not reposition tissue; instead, placed in a mesh or fanned pattern, they provide gentle support and are used chiefly for a biostimulatory, skin-tightening effect as the surrounding tissue responds to the material. Think skin quality and subtle firmness rather than lift. Fine mono options such as the Epline thin mono are typical of this category.
Cog (barbed) threads
Cog threads carry barbs — small projections cut into or moulded onto the filament — that grip the tissue and allow genuine repositioning. These are the lifting threads: they engage tissue along their length and hold it in a new position while the material is absorbed and a supportive response develops around it. Barbed designs vary in dimension and barb configuration, from bidirectional barbed threads to stronger multidirectional 3D cog designs, each suited to different loads and regions.
Screw (spiral) threads
Screw threads are wound in a spiral, sometimes as a single or intertwined filament around the needle. The spiral geometry is intended to add volumising support and a stronger biostimulatory effect in a localised area — sitting conceptually between the pure support of monos and the frank lift of cogs. Fine screw options such as the Epline thin screw are used where localised volume and firmness are the aim.
Matching Thread to Region
Because the three types do different things, region and goal should drive the choice rather than habit.
- Jawline and jowls — where the aim is repositioning and definition, cog threads do the structural work, often supported by monos to firm the overlying skin.
- Cheeks and mid-face — cogs can reposition descended tissue, while screw threads may add localised support; the plan depends on whether the problem is descent or deflation.
- Neck — commonly a skin-quality and mild-tightening target, where mono threads (and careful patient selection) suit the thin, mobile tissue better than aggressive lifting.
In practice these are frequently combined within one treatment: cogs to reposition, monos to improve the skin envelope, screws for localised firmness. Options such as the Croma Princess screw thread sit within broader ranges that let a practitioner mix types across a single plan.
A useful way to think about it is to separate the two jobs a thread can do. The first is mechanical — physically moving tissue and holding it, which only barbed cogs achieve reliably. The second is biological — provoking a supportive tissue response as the polydioxanone is absorbed, which every PDO thread does to some degree but which monos and screws are chosen for specifically. Deciding whether a region needs repositioning, stimulation, or both is the assessment that should precede any choice of thread.
Realistic Expectations and Safety
Thread lifting has been over-marketed in the past, and honest positioning protects both patient and practitioner:
- Results are visible but modest. Threads provide support and repositioning, not the degree of change a surgical lift achieves. Patient selection — appropriate, limited laxity — is everything.
- The effect is temporary. PDO is absorbed over months, so results are not permanent and maintenance is part of the conversation. Longevity figures should be given as typical ranges, not guarantees.
- It is a clinical procedure. Transient swelling, bruising, dimpling or discomfort can occur, and placement belongs in trained hands. This article is educational and does not describe an insertion technique.
Sourcing matters too: threads should arrive with clear specification and intact, sterile packaging, and the type should be matched both to the intended effect and to the practitioner's own training.
The Takeaway
Mono, cog and screw PDO threads are not interchangeable. Monos tighten and improve skin quality, cogs reposition and lift, and screws add localised support and stimulation. The best plans usually blend them — cogs for structure along the jawline, monos for the skin, screws where localised firmness is wanted — chosen around a careful assessment of what each region actually needs.
Review the options in the PDO threads range.