TestLift Thread: What Changes Between U-Shaped and I-Shaped? How to Choose Shape and Material

Thread lift threads change their characteristics depending on shape (direction of barbs, U-shaped or I-shaped, thickness) and material (PDO, PLLA, PCL)[1][2]。Strong lifting is achieved with U-shaped threads fixed at the temples, while I-shaped threads are recommended to minimize pain and discomfort according to reviews, though U-shaped threads are reported to cause more bleeding and dimple-like indentations[1]。TestLift-type PDO threads with barbs also become easier to choose when positioned along this "shape and material" axis[1][2]。

What's the Difference Between U-Shaped and I-Shaped?

The difference lies in where the thread catches and provides support. U-shaped threads are suspension-lift types that fold back and are fixed at the temples, with reports showing an 85–90% rate of visible lifting when fixed at the temples[1]。However, complications are more frequent, including bleeding at 15–20%, dimple-like indentations at 12–18%, and tissue trauma at the thread exit at 5–10%[1]。

I-shaped threads place less burden on tissue and cause less discomfort, with complications reported at less than 5%, though the lifting effect is modest[1]。Reviews conclude that combining both approaches for each patient yields better results than relying on one method alone[1]。

What Changes with Barb Direction and Thickness?

Barb direction is classified as unidirectional, bidirectional, or multidirectional[3]。Multidirectional barbs are explained to increase grip on tissue, distribute tension evenly, and reduce thread migration[1]。

Thickness is also a selection factor. Thicker threads with larger barbs are suited for heavy lower-face sagging, while thinner threads with fine barbs are suited for delicate areas like around the eyes[1]。Barbed threads are noted to cause more redness, bruising, pain, and infection compared to smooth threads[4]。

PDO, PLLA, PCL: Does Material Affect How Long Results Last?

The duration threads remain in the body varies by material. In a Japanese compilation of 111,948 cases, the duration of effect is approximately 6–12 months depending on material and location, with PDO threads breaking down in 6–8 months and PCL threads lasting about 12 months[2]。Animal studies cited in literature show PDO lasting 6 months, PLLA 12 months, and PCL 2 years[5]。

Complications also differ by material. PCL causes more sensitivity and bruising, PDO has less inflammation but more infections, and PLLA falls in between[4]。However, the same review notes that safety and efficacy data specific to each type are limited[4]。

Absorbable Threads vs. Non-Absorbable Threads: What's the Current Standard?

The current standard is absorbable threads. Non-absorbable barbed threads have been replaced by absorbable threads, which are explained as safer, easier to correct, and carry significantly reduced risks of numbness and thread extrusion[6]。PDO breaks down gradually within the body over several months and has both lifting and collagen-building properties, according to reviews[1]。Textbooks define Thread lift as a minimally invasive method in which barbed threads are inserted through the skin to lift soft tissues of the face and neck, compared to surgical incision[7]。

How Long Do Results Last?

Regardless of thread type, results are not permanent. Systematic reviews citing reports show that lifting-only results begin to fade at 6 months, with all jawline effects and 80–100% of mid-face effects lost by 12 months[3]。Large-scale compilations also show effect duration of approximately 6–12 months[2]。

The compilation of 111,948 cases explicitly notes its limitation that complication and long-term outcomes could not be assessed due to anonymized aggregate data[2]。It's worth remembering when choosing that the duration threads remain in the body and the duration visible effects persist are not the same[3][2]。

What to Confirm at Consultation

Confirm which shape (U-shaped or I-shaped), thickness and barb type, and material thread should be used for your degree and location of Sagging (skin laxity), and where fixation should be placed[1][2]。Since strong lifting and fewer complications are difficult to achieve together, deciding which to prioritize first makes the consultation easier[1]。

Effect duration varies by material and location[2]。How many months to expect for your face and what to do when results fade should be decided with your doctor at consultation after they examine your face.