Hybrid Thread Lifting: Comparing U vs. I Shaped Threads and Tailoring Techniques by Anatomy

Thread lifting has become a cornerstone in the field of aesthetic medicine, offering a minimally invasive alternative for facial rejuvenation without the need for traditional surgical procedures. Especially in Asian clinical practice, where patients often seek natural-looking enhancement with minimal downtime, thread lifting has evolved into a nuanced, anatomy-based procedure.

In their comprehensive review, Dr. Gi-Woong Hong and colleagues dissect key clinical insights into thread types, insertion techniques, age-specific strategies, and complication management. The study gives particular attention to the differences between U-shaped and I-shaped barbed threads, and how they can be tailored to suit varying facial zones and patient profiles.

Understanding Anatomy Behind the Lift

Thread lifting is most effective when it works in harmony with the face’s natural dynamics. During smiling, for example, the anterior cheek tissues elevate anterosuperiorly, while the lower face narrows due to lateral superior movement of the perioral tissues. These shifts suggest ideal vector directions for thread placement that mirror youthful facial structure.

This physiologic lifting pattern informs thread insertion design: by replicating these directional vectors with barbed threads, surgeons can achieve more natural and youthful outcomes. However, to do so safely, an in-depth understanding of the Superficial Musculo-Aponeurotic System (SMAS) is vital.

The SMAS layer varies in thickness across facial regions—thicker near the parotid and preauricular area, thinning drastically near the nasolabial folds. This anatomical variability mandates adjusted insertion depths to avoid damage to underlying muscles or mucosal perforation.

Navigating the SMAS and Retaining Ligaments

Beneath the skin, the Superficial Musculoaponeurotic System (SMAS) serves as a fibrous network connecting the facial muscles to the dermis. The thickness and depth of the SMAS vary depending on facial region—thicker laterally in the parotid area and thinner medially near the nasolabial fold. When threads are placed at inappropriate depths (either too superficial or too deep), complications such as visible thread outlines, dimpling, and inadequate lift may occur.

Another anatomical consideration is the retaining ligaments—such as the zygomatic and mandibular ligaments—which anchor soft tissue to the underlying skeleton. These ligaments resist movement and can obstruct the lifting effect of threads if not properly accounted for.

For optimal lift, the goal is to position the barbed threads in mobile areas between fixed ligaments, anchoring the sagging soft tissue without creating excessive tension or dimpling at the entry point. This balance is key to natural-looking outcomes.

Thread Types in Focus: U-Shaped vs. I-Shaped Threads

Hong et al. provide a detailed comparison of U-shaped and I-shaped barbed threads, both commonly used in clinical practice, yet differing significantly in function, technique, and application.

U-Shaped Vector: Structural Suspension and Deep Lifting

U-shaped Thread (often called "suspension threads") are long threads that enter from a fixed point—typically the temporal scalp—and extend downward in a V or U pattern. The barbs face both directions, creating strong anchorage within the soft tissue once they are pulled tight.

This thread design is ideal for areas of moderate to severe ptosis, such as the jawline, jowls, and nasolabial folds, where heavier tissue requires structural lifting. However, these threads are inserted via a sharp needle and usually exit the skin, increasing the risk of bleeding, nerve injury, or facial artery perforation.

These threads demand precision and detailed anatomical knowledge, especially in regions such as the perioral area where key vessels and nerves lie superficially.

I-Shaped Threads: Minimally Invasive Floating Threads

I-shaped threads (also called "floating threads") are generally shorter, inserted with a blunt cannula, and do not require an exit point. Because they cause less trauma, they are ideal for contour refinement, particularly in the cheekbones, periorbital area, or jawline of younger patients.

These threads do not provide the same level of structural lifting as U-shaped threads, but they can reposition soft tissue subtly and stimulate collagen production over time. They are especially useful in thin-skinned areas where sharp needle insertion might otherwise cause dimpling or hematoma.

In Summary:

• U Shaped threads: Greater lift, higher risk, more suited for structural repositioning.

• I Shaped threads: Safer, subtler, more appropriate for early signs of aging or fine-tuning.

Hybrid Techniques: Combining U-Shaped Threads & I-Shaped Threads

One of the most clinically relevant contributions of this study is the advocacy for hybrid thread lifting, a method combining the strength of U-threads with the subtlety of I-threads. For example, a practitioner might use U-threads to elevate the lower face and jawline, while placing I-threads around the nasolabial folds or lateral cheek for fine-tuning.

This multi-thread approach addresses both vertical lifting and volume redistribution, providing a more comprehensive rejuvenation—especially in middle-aged patients.

Personalizing Thread Lifting by Age

The study also presents a practical framework for selecting thread strategies based on the patient’s age and skin condition.

• Patients in their 20s–30s: Typically seek facial contour refinement without volume loss. I-threads are usually sufficient.

• Patients in their 40s–50s: Begin to show midface descent and deeper nasolabial folds. A hybrid approach using both thread types works best.

• Patients in their 60s and older: Require more conservative lifting focused on repositioning rather than reshaping. Threads may be used as part of a combined treatment plan with fillers or energy-based devices.

Conclusion

Thread lifting is no longer a one-size-fits-all treatment. As this paper demonstrates, successful outcomes depend on a deep understanding of anatomy, proper thread selection, and precise vector planning. The comparison of U-shaped and I-shaped threads, combined with hybrid lifting strategies, provides clinicians with the tools to deliver natural, long-lasting, and safer results.

For doctors and surgeons in the field of facial aesthetics, adopting these principles will elevate the quality of thread lifting practice, and most importantly, patient satisfaction.

Reference:

1. Hong, G.-W., Lee, H., Jang, Y. J., Hong, S.-H., & Lee, W.-J. (2025). Pre- and post-procedural considerations and thread types for thread lifting. Life, 15(1), 85. https://doi.org/10.3390/life15010085

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