The classification, application and management of thread should comply with the relevant provisions of the Medical Device Classification Catalogue of PRC.

By April 1, 2022

Subdirectory 02, without origin of surgical instruments.

Thread material, usually composed of non-absorbable or absorbable polymers. Auxiliary tools, with or without a needle.

Abiding by supervision of Grade III medical device management.

The main body of thread is composed by polypropylene, the diameter is 3-0, the length is 400 mm, the cone diameter is controlled within 1.2–1.5 mm. The thread including 8 hollow polyl-lacto-glycolic acid (PLGA) cones in the same row, which are fixed by prefabricated thread junction clips with a spacing of 1 cm.

Non barbed thread is preferable, for example, smooth thread or spiral thread.

It is advisable to choose barbed thread, facial cone lift thread, suturing thread, etc.

It is advisable to choose non barbed thread.

It is advisable to choose non barbed thread, for example smooth thread and spiral thread.

Characteristic. The left angled design is used to lift the eyebrow. The double straight needle two-way barbed thread is selected. The overall design can be based on the specific lifting position to determine whether it needs to shift in the direction of the brow or the tail of the eyebrow. It can also adjust the shape of eyebrow. The middle part is designed to lift the head of eyebrow, improve the sagging and partially improve the sunken of mid-forehead. It is advisable to choose cannula bidirectional barbed thread (Figure 1).

Characteristic. Cannula bidirectional barbed thread was selected. The upper part was used to lift the ocular tail by anchoring the lateral orbital thickening, and the lower part was used to lift the superolateral part of the zygomatic fat pad to improve the mild malar-palpebral groove and sagging of inferior eyelid. knotting and reversely anchored to the deep temporal fascia (Figure 2).

Characteristic. The cannula bidirectional barbed thread or double straight needle two-way barbed thread was used to lift the zygomatic fat pad, while taking into account the fullness of the middle face and completing the aesthetic plane. Figure 3 adds an adducent fixation design on the basis of Figure 4, which is more suitable for those with mild zygomatic arch enlargement (Figures 3, 4).

Characteristic. Cannula bidirectional or unidirectional barbed thread is used to lift the zygomatic fat pad superolateral to improve the nasolabial groove, especially suitable for the patients with mild zygomatic arch enlargement. The proximal end of the threads placed in the nasolabial fat septum, and the distal end can be knoted or not, but all of them need to be reversely anchored to the deep temporal fascia (Figure 5).

Characteristic. Cannula bidirectional or unidirectional barbed thread or facial cone elevated thread is mainly used to improve the jowl and indirectly reshape the mandibular margin through indirect anchoring technique of platysma auricular ligament. The proximal thread should be precisely embedded in the Jowl fat (Figure 6).

Characteristic. Reversing design was made on the upper margin of zygomatic arch by using the cannula bidirectional barbed thread. The proximal of the thread could be knoted or not, and the distal end is anchored in the deep temporal fascia. It is mainly used to improve the lateral buccal sagging and assist in reshaping the morphology of mandibular margin (Figure 7).

Characteristic. The integrated design of mandibular margin and lateral buccal is carried out by burying the double straight needle two-way barbed thread in the platysma auricular ligament. It is mainly used to improve the lateral buccal sagging and reshaping the morphology of mandibular margin (Figure 8).

Characteristic. This group of designs used to improve mild to moderate sagging of middle lower face, deepening of nasolabial groove, jowl and morphology of mandibular margin. A variety of threads can be chosen to finish the designs respectively. For example, anchoring thread design of cone elevated thread (Figure 9), inverted U design of bidirectional barbed thread (Figure 10), folding and fixing forward and backward design of cannula unidirectional or bidirectional barbed thread, etc. (Figure 11). For patients with obvious external enlargement of zygomatic arch, cannula bidirectional barbed thread can be applied into forward and backward design of upper or lower edge of zygomatic arch respectively (Figure 12). The distal of threads should be anchored in the deep temporal fascia, and the proximal of threads should be precisely embedded in the nasolabial fat septum (Figures 9, 10).

Characteristic. This group of designs used to improve mild to moderate cervical sagging and morphology of mentocervical angle. A variety of threads can be chosen to finish the designs respectively. For example, anchoring thread design of cone elevated thread (Figure 13), burying design of bidirectional barbed thread (Figure 14), net design of double straight needle thread (Figure 15). Make full use of platysma auricular ligaments, both sides of threads are all indirectly anchored.

Characteristic. Smooth thread and spiral thread can be applied to different designs according to different requirements. Application of crossroad net design can boost the volume. Combined application of spiral thread and barbed thread through vertical burying can assist the lifting effect of barbed thread. The spiral thread buries perpendicularly to the frontal muscle, platysma and other intramuscular burying can relax the muscle respectively. The operation above can also facilitate the improvement of frontal and neck lines as well as lifting of lower face. The intramuscular thread parallel to the orbicularis oculi muscle can enhance the muscular strength to improve the herniation of lower eyelid fat (Supplementary Figures S1, S2).

It is usually caused by local trauma and impairments derived from repeated puncture (36). Preventive approaches include add epinephrine into local anesthetics which can reduce hemorrhage, be familiar with local anatomic structure, make sure accurate puncture in operation to minimize trauma (37). Treatments mainly include hot compress, physiotherapy and application of specific medication (38).

It is usually caused by damaging of large and middle arteriovenous systems (39). Preventive approaches include familiarizing physicians with the atlas of blood vessels and taking care of operational level (40). Treatments include aspiration, compression, drainage, and hematoma removal if necessary (41).

Generally, it is caused by the tightening and enhancing effect after burying the thread immediately, and it is also related to the cross-zone treatment (42). The stinging pain is caused by slight displacement and slippage of the serration, irritation of the subcutaneous sensory nerve (43). Symptoms mentioned above are generally limited to one week after embedded (44). Preventive approaches include avoiding massages in the short term and reducing large facial movements (43). The symptoms can be recovered without treatment naturally (43).

It is usually caused by shallow burying of thread or superficial puncture of facial retaining ligament (44). It is most likely to occur in three regions, the region of middle buccal sulcus, the region of junction of zygomatic fat pad and masseteric cutaneous ligament as well as the region of the zygomatic arch ligament and parotid masseteric fascial ligament (45). Preventive approaches include fully evaluate the subcutaneous fat thickness of patients, clearly define and mark ligament-related anatomy, burying level of thread need to be accurate within operation (10). The symptoms can be treated according to specific situation, mild case can be treated by local massage or restored within a month automatically (46). For patients who cannot waiting or the depression is really severe, combined treatment with fillers or subcision near the depressed site to loosen the adhesion are applicable (47).

It is mainly caused by asymmetry of bilateral designing marks, uneven dosage of local anesthetics, inaccurate puncturing level and difference concerning amount and direction of buried thread (48). The consistency of facial symmetry and sagging should be evaluated correctly before treatment (48). Symmetrical concept and precise operation are consistent in whole process, comparison and adjustment will always stay in tuned. Mild asymmetry can recover naturally within 1 month (7). Sever asymmetry can be corrected by thread or filler.

The main reason is that the puncturing points at both ends of the thread are shallow and close to or touching the dermis (49). With the movement of face and the effect of gravity, the thread gradually pushes up the skin, causing pain or breaking the skin (50). In addition, another reason is due to excessive facial movement to break the thread (51). Preventive method is pay attention to burying depth of both ends of the thread (52). Cutting off the excess thread directly or indirectly if it happened (52).

Crossing of barbed threads is easy to noose and causes bumps, stinging, etc. (8). In principle, the barbed threads should not be buried intersectly (8). Or at least, the cross-designed threads need to be placed in different depth. Making a small incision at the puncturing point or cutting the thread residue as short as possible can also help to avoid the symptom (53).

Main reasons are as follows. a)

Infection related high risk factors such as immune system disease, history of hormone application and diabetes, or impaired glucose tolerance were not recorded before treatment.

The main reason is that the concentration of local anesthetic is too high, the quantity is too large and the waiting time is too long (56). It is also possible that the neural damage derived from improper depth of injection or burying (56). Damage is generally reversible and can recover naturally. Open surgical repair should be considered to treat permanent neural injury if the patient fails to recover after 2–3 months (57).

Due to improper puncture during treatment, it can enter the capsule of parotid gland or essence of parotid gland, which will lead to painful, local swelling (58). The symptoms will be aggravated when eating. Preventive methods include be familiar with the corresponding local anatomy and do not puncture too deeply (59). The therapy is mainly conservative treatment with local pressure, the symptoms can be relieved within a week. If further local intractable swelling occurs, it may cause by leakage of gland attributed to parotid duct injury, which requires emergent specialist treatment (60).