Polydioxanone thread lifting
Professor Syed Haq discusses the popularity of thread-based technology to bring about skin rejuvenation, skin tightening and lifting of the face, as well as treating other body parts
Improved understanding of the use of Polydioxanone (PDO) threads as the principal underlying device in aesthetic/cosmetic non-surgical interventions, alongside correct patient selection and the increased experience of clinicians in the United Kingdom, has created a significant upsurge in their use in the past five years. Invariably this has led to improved patient outcome in general, though the application of this powerful technology has to be taken in the correct context.
PDO is a colourless, crystalline, biodegradable synthetic non-animal based polymer. Chemically it is based on a polymeric structure composed of multiple repeat ether-ester subunits. It is obtained by ring-opening polymerisation of the monomer p-dioxanone.
The medical device manufacturer Ethicon first used polydioxanone suture technology worldwide for over a decade as a means of wound closure. In South Korea polydioxanone has seen a revolution with PDO threads being used for the last seven years both for orthopaedic and cosmetic
Historically, the earliest reports of surgical facial rejuvenation go back as far as 1911 by Koll et al. The use of endoscopic malar and midface suspensions were reported by Anderson and Lo et al. in 1998, which paved the way for the future use of thread lifting suture technology as a means of facilitating facial augmentation non-surgically. It was not until four years later in 2002 when Sasaki and Cohen provided the first definitive report of malar fat pad elevation, using a variety of suture material from polypropylene, polyglactin 910, Gore-Tex and Vicryl. This work was further supported in 2002 when non-barbed suture suspensions were used with temporal fascia fixation in bringing about midface augmentation. The first description of barbed suture suspensions to be commercialised was presented in 186 patients by Sulamanidze et al. when the Aptos [anti-ptosis sub-dermal suspension] was described. In 2004, contour threads permanent non-absorbable sutures were introduced to anchor temporal fascia, derived once again using a polypropylene base. These barbed threads were configured in a helicoidal pattern, but failed to gain momentum owing to their “permanence”.
PDO has a long safety record in surgery. In South Korea, Polydioxanone has been used for over seven years in orthopaedics (to treat frozen shoulders, tennis elbow, golfer’s elbow, etc.) and in cosmetics (for skin rejuvenation, skin tightening and face ‘lifting’ indications). The popularity of PDO threads can be attributed to the safety of Polydioxanone, ease of insertion of the threads, excellent reproducible and sustainable results, minor side effects and the very low incidence of complications.
More recently, in 2011 the Korean FDA approved the use of non-barbed absorbable suture suspensions using polydioxanone as an indication in lipolysis, collagen regeneration, neo-vascularisation in the subcutis and dermis.
Why use polydioxanone?
The main advantage is that PDO is biodegradable. This synthetic polymer is highly versatile and was originally used as a mono- or multi-filament thread. Biodegradation of PDO occurs through a process of hydrolysis over a time period of between six to eight months. The main method of elimination is via the kidneys.
In contrast, the introduction of a poly-L lactic acid coated fine suture using bidirectional cones, was also introduced as means of addressing issues of facial rejuvenation a number of years ago. Silhouette Soft is inserted in the sub-dermal and adipose tissue. A number of issues using this type of technology have been identified from its underlying weak tensile strength, issues of repositioning of the cones, granuloma formation, an increased risk of skin puckering, cone visibility and a lack of lipolysis are limiting factors.
The principal mode of action of polydioxanone in the dermis was first thought to be wholly reliant on the creation of new collagen by a foreign body reaction, which promoted wound healing through tissue contraction. This traditional view of shortening of collagen failed to fully explain what was happening on a histological level. Howe and co-workers in 2006, identified that subcutaneous tissue fibroblasts exhibited greater pleomorphism than originally postulated being responsible for cytoskeletal remodeling, and this was evidenced by a process defined as mechano-transduction, where fibroblasts are able to self sense, process and respond to mechanical stimuli in their microenvironment and importantly regulate physiological function nearby. The overall effect of this sees actin polymerisation following matrix deformation by external mechanical stimuli. The polymerised actin facilitates cell contraction and activation of the mitogen activated protein kinases (extracellular signal regulated kinases 1 and 2 – ERK1/2) which in turn regulates gene expression, protein synthesis, extracellular matrix modification, cell differentiation, and potentially promotes tissue growth.
The underlying mechanisms that define the regenerative changes that take place in the dermis and subcutis from polydioxanone threads includes neo-collagenesis (Fig 1C/E) from a foreign body reaction (Fig 1B), microcirculation stimulation, increased metabolism, lipolysis, muscle relaxation and increased tissue adhesion.
In summary, a foreign body reaction is observed together with elastic fibrosis around the area where the thread is inserted. Importantly, studies have shown that increasing the density of threads, that is when placed either in multi-layers and or in close apposition, creates a more dense structural supporting framework.
Apart from the way in which threads are placed, the diversity amongst the different types of PDO threads currently available allows the experienced and well-informed clinician to tackle many of the aesthetic issues requiring augmentation.
The indications for PDO threads are as follows:
1. Face Contouring
2. Wrinkle attenuation
Crows feet and peri-orbital zone
3. Skin rejuvenation—general and of atrophic scars
4. Skin tightening
5. Pore size reduction
6. Volume reduction (lipolysis)
7. Hair rejuvenation
8. Neck lift
Double chin reduction
Platysmal relaxation—vertical and horizontal
9. Muscle relaxation
10. Body contouring
Upper arm and chest tightening
Abdominal tightening and reduction
11. Tissue healing and pain control
Currently, various knotless thread lifting devices using PDO are popular in aesthetic clinics. The thread forms a V-shape with portions residing outside the needle/cannula and the other half inside the caliber. After inserting the needle or cannula, one simply removes the needle or cannula resulting in the thread ﬁxation inside the skin without anchorage or knots.
An example of the use of multiple monofilament PDO threads provides an alternative approach to facial augmentation by not using cog PDO thread technology. This type of approach is most commonly used in S. Korea.
The advantage of using mono-filaments facilitates a quick and simple procedure. Mono-filament PDO threads are also being used for wound suturing that require prolonged tensile strength. In general Polydioxanone threads remain in situ, taking about six months to be fully absorbed, which is longer than both Vicryl and Dexon, providing an added advantage in aesthetic augmentation. The use of cog threads should be one of caution. Both uni- and bi-directional cogs have inherent issues with slippage and dimpling. This is less common than with multi-directional cogs. In my experience the most stable lifting cog is based on the three-dimensional projection. This for the uninformed should not be confused with the spiral thread. 3D cog threads provide excellent lift of the face or neck provided the anchor point is well chosen and the threads are placed at the level of the superficial muscular aponeurosis (Figures 5 and 6). Whether mono/screw or cog, if the PDO threads are placed correctly with respect to tissue depth and vector orientation, a patient should experience improved clinical changes over the first four months.
The most important limitation of this procedure is that it is only indicated for a modest degree of facial soft tissue laxity. Careful patient selection through experience in midface lifting using absorbable 3D cog sutures is more effective than using barbed bi- or multi-directional sutures. The reason for this is due to better techniques in fixation, combination thread use and better quality cogs being made available. The most favorable anatomic characteristics for absorbable thread lifting are low body mass index, minimal fullness to the soft tissues, strong underlying bony projections to support the elevated tissue, and good skin quality.
Many changes have taken place in PDO thread technology over the past three years. The clinical indications for use seem to be ever expanding. At present PDO thread lifting appears to be providing a viable solution for those patients who either choose not to undergo surgical intervention to resolve their clinical issues, or for those patients who are caught between the standard non-surgical and surgical approaches. I believe that this transition group of patients will continue to expand – provided that further studies are conducted using PDO thread therapy that explore and deliver long-term clinical results without compromising safety. To that end it is a fundamental requirement that standardisation in the method, techniques, training and product quality are at the heart of the PDO thread therapy movement. Strict regulatory control and the establishment of non-profit organisations like the Association of PDO Thread Therapy UK will be paramount to ensure that the highest levels of outcome with patient safety are adhered to.
I would like to take this opportunity in dedicating this article to my family and friends both past and present, with particular reference to Dr Sayyid Azizul Haq and Mrs Fazilatun N. Haq. I would also like to pay particular thanks to my mentor in this area Dr Jacque Otto, who with his wife Amanda and son Vernon have been outstanding throughout.
SH – 10 Harley Street London W1G 9PF Tel: 0207 467 8458