REGISTRO DOI: 10.69849/revistaft/ni10202412180716
Ana Moreira Marques1
ABSTRACT
This study focuses on both the individual understanding of how polydioxanone2 threads and hyaluronic acid fillers work, plus the combined used of both techniques to improve the anti-aging treatment and deliver the best possible results to our patients. The combination of treatments is, in most cases, the best approach to reduce signs of aging, improve skin quality and fix asymmetries and face proportions.
However, the combination of treatments should be well studied and planned so that the single procedures result in a balanced and efficient harmonization.
The aim is to get together information which reinforces the hypothesis that PDO threads are more easily degraded when applied together with hyaluronic acid fillers.
Methods: This study is a literature review. It is important to use planning skills, money resources and scientific knowledge to take maximal advantage of the options we have available in aesthetic medicine and get the best outcome. With that purpose, a detailed literature search about the topic was done in Pubmed. Several articles were used to elaborate this study, including case reports and laboratory in vitro experiments.
Results: Polydioxanone is a homopolymer of paradioxanone, biodegradable by hydrolysis, since in contact with watery substances, its ester chains are broken and low molecular weight chain segments diffuse, which leads to its heterogenous biodegradation by layers, from the periphery to the center. Hyaluronic acid is a biocompatible and widely available polysaccharide from the glycosaminoglycan family. It is a hydrophilic polymer and so, it improves water retention. In vitro experiments have shown that hyaluronic acid, induces rapid biodegradation of PDO threads by hydrolysis, starting already 24h after the contact with polydioxanone, leading to an increase in the fibers’ interlaminar and intrafibrillar space, with those empty spaces corresponding to zones of hydrolysis. At 48h, these spaces increase as the dissolution of the peripheral and central layers occurs. After 72h, empty spaces in the central layer and a frayed pattern on the periphery of the thread are seen, with disorganization of fibrils, breakage of molecules and loss of mass. The degradation happens from the periphery to the center, causing small cracks and allowing water to diffuse into the center. A case report of a woman with complications post PDO thread implantation, in which hyaluronic acid was injected in 3 occasions (0,5mL each time) as a way to try to speed up the process of polydioxanone degradation and accelerate the treatment of these complications, showed that after 21 days, the patient showed improvements, with reduction of oedema and at 45 days there were visibly less skin folds and irregularities caused by the thread.
Conclusions: The stipulated hypothesis that hyaluronic acid increases the speed of degradation of PDO threads is correct. As such, both products shouldn’t be used simultaneously, not because complications will develop, but because it is not an efficient, result friendly choice, since PDO threads’ durability will significatively decrease. Contrarily, in cases in which PDO thread implantation lead to complications, injecting of hyaluronic acid could be an option to accelerate the treatment of those complications, as an alternative to surgical intervention.
Keywords: PDO threads; biodegradation; hydrolysis; Hyaluronic Acid; Antiaging
1. Introduction
As we get old, several changes in our body start to physically reveal the aging process. Aging consists in the progressive slowing down of cutaneous metabolism, which starts around 25 years old and progresses throughout our lives. The decrease of skin elasticity and skin quality due to loss of collagen fibers, the loss of facial fat tissue, bone reabsorption and decrease in bone density leads to a loss of facial support. These are some of the changes that lead to the appearance of wrinkles, skin laxity, appearance of skin pigmentations, rough-like skin texture, loss of facial definition and change in facial shape to an inverted triangle figure. (1)
Several intrinsic and extrinsic factors influence how fast and how well we age. Intrinsic factors are, for example, genetics, and extrinsic factors are usually marked by life-style choices and living conditions, such as smoking, air pollution, solar exposition, free radicals. (2)
With the development of aesthetic medicine, there’s a wide offer of products, techniques and procedures available to help us fight aging signs and improve skin quality. In many cases, the best approach for a “better-aging”, is done by using a combination of procedures with the aim to obtain the best harmonic results for our patients. As aesthetic medicine offers non-chirurgical options, which have a short recovery time, less post-op complications and are less invasive, these services are increasingly being requested. (3) However, when we talk about combination of procedures and products, we must pay close attention to how they work together, how compatible they are and if they potentiate one another or not. The aim of this study is to review the literature about combination of procedures in facial harmonization, specifically, the combination of PDO threads and hyaluronic acid.
2. Methods
A classic review was conducted using Pubmed electronic database, using the query “hyaluronic acid OR polydioxanone threads OR biodegradation OR hydrolysis”. There was a selection of articles, in which in vitro and microscopic experiments were done, and a case report was also selected. During the process, topics such as polydioxanone threads and hyaluronic acid composition, their application techniques and indications for its use, were taken into account. Language criteria was not applied, since articles in English, Spanish and Portuguese were considered important for the matter. After thorough examination of the articles’ content and proper contribution to this study, 22 articles were finally chosen.
3. Results
3.1. General approach on Polydioxanone Threads
Polydioxanone is a homopolymer of paradioxanone (1,4-dioxanone-2-one), which is a strong, synthetic, biodegradable suture. It can be violet or colorless and it is absorbable and highly flexible. (4)
PDO threads can be of three different types: “smooth monofilament plain threads, monofilament spiral or screw, multiple monofilament threads, and barbed sutures” and they can be hold in a canula or a needle. (5)
Studies have shown that polydioxanone is degraded by hydrolysis, since in contact with watery substances, ester chains, present in its chemical formula, are broken and low molecular weight chain segments diffuse, which leads to its heterogenous biodegradation by layers. (6) The thread is completely reabsorbed by the body withing 4 to 6 months, depending on how fast the hydrolysis process occurs for that individual. This means that the longevity of the thread is higher if its biodegradation is slower. (4,5)
Already the insertion of the thread leads to a granulation process in the tissue and production of different types of collagen, as well as myofibroblasts and fibroblasts. (5) Then, a fibrotic reaction happens around the thread while it’s still not degraded, which, helps the lifting effect on flaccid tissues. (4) The hydrolysis of the thread also potentiates fibroblast production and neocollagenesis in that area. As a result of this tissue regeneration, skin is strengthened, tightened and becomes more elastic. (5) Therefore, PDO threads have been used for reverting sagging skin, fixing deep skin folds, lipomatosis and rhytidosis. (4)
The insertion of PDO threads it’s not usually a procedure with a lot of severe complications, but their implantation in the wrong skin plane or/and incorrect placement technique, inadequate asepsis and the suture too close to the entry point can lead to symptomatic complications. Some of those, registered in case reports, are “oedema, ecchymosis, thread surface palpation, skin dimpling or folding irregularities” and possibly skin infections.(5) When facing this situations, the patient might require the aesthetic medicine doctor to proceed with the removal of the thread, that can be done surgically, usually with minimal invasive surgery, also by heat based therapies such as radiofrequency, as well through its exposition to aqueous mediums. (4, 7, 8, 9)
3.2. General approach on Hyaluronic Acid
Hyaluronic acid is a widely available polysaccharide from the glycosaminoglycan family, with viscoelastic consistency. It is a biocompatible substance, since it is found naturally in the human body, as a “high molecular mass in the synovial fluid that surrounds the joints, in cartilage and in the tissues of eyes and skin”, thus being a substance with minimal immunogenicity with properties that allows it to be used in a variety of medical and aesthetic situations.(4,10,11) It is a biodegradable, hydrophilic polymer and so, it improves water retention. “It can hold water molecules up to 1000 times the molecular weight.” Being present in the epidermis, dermis and extracellular matrix of most connective tissues, it plays a major role in the dermis’ metabolism, in wound healing and reparation of tissues.(4,12,13,17)
In aesthetic medicine, hyaluronic acid fillers are a major tool for facial harmonization and rejuvenation. The product is safe and, with non-invasive techniques, it is possible to immediately and predictably see the results we aim for. The great majority of hyaluronic acid applications are meant to reshape, fix asymmetries and fight the loss of facial volume due to aging, allowing a good correction of changes that are a consequence of processes such as bone resorption, loss of fat tissue and loss of skin collagen fibers. Parallelly, as it retains water, it can also improve skin quality, hydrating it. This efficacy on showing results make it the treatment of choice for most patients who look for aesthetic medicine services to ease wrinkles, nasolabial folds, marionette lines, pre-jowls sulcus, temporal sinking, fine perioral lines, dark circles; potentiate cheek volume, lips, the chin, the mandibular line and even to do rhinomodulation. As so, there’s a variety of facial areas in which the hyaluronic acid fillers can be applied. However, this procedure needs to be done with caution, with proper and deep knowledge of facial anatomy and good planning to avoid complications such as Tyndall effect in the periocular region, inflammatory or infectious nodules and vascular compromise. (14,15,16)
Knowing how the aging process affects the different facial skin layers (epidermis, dermis, superficial fat layers, SMAS – superficial muscle aponeurotic system, deep fat layers and retaining ligaments belonging to connective areolar tissue, periosteum), defining which layer we must work on, which type of effect we want and the filler procedure, is essential to define a good strategy for filler application. In the same way, choosing the right product is also a key step (table 1). (17) There’s a high range of fillers available and, according to our goal, rheology helps us selecting the one with the most appropriate G’ – elasticity or capability to retain the original shape after a dynamic force is applied, G’’- viscosity or the resistance to dynamic forces, which determines extrusion force and the cohesivity is the strength between the hyaluronic acid chains which determines the capacity to remain intact and not dissociate. According to the density of the gel, the reticulation of the filler, which corresponds to its ability to retain water, changes. More reticulated products retain more water and cause more edema. (17, 18)
Combining the knowledge of the aging process, the skin layers, filler application techniques and the different types of products we have available in the market, will lead to a more efficient service and outcomes will be more promising.
3.3. The combination of PDO threads insertion and hyaluronic acid application
With the wide variety of option of procedures and products available nowadays in aesthetic medicine, the combination of techniques is many times necessary to obtain the best result possible. However, scientifically, it is necessary to access if a specific combination is indeed productive and efficient. When it comes to the combination of PDO threads and hyaluronic acid fillers, some clinicians have created a protocol which consists in this association of products.
Nonetheless, in vitro experiments have shown that hyaluronic acid, which is hydrophilic, induces rapid biodegradation of PDO threads by hydrolysis, starting already 24h after the contact between both materials. (4) In this study, three segments of a monofilament were submerged in 1mL of hyaluronic acid. After 24h, 48h and 72h, the threads were removed and dried and, afterwards, observed under an ultramicroscope. As results, it was found that after 24h, there was an increase in the fibers’ interlaminar and intrafibrillar space, with those empty spaces corresponding to zones of hydrolysis. After repeating the analysis at 48h, these spaces increase as the dissolution of the peripheral and central layers occurs and retention of aqueous content between the thread core and the peripheric layer is noticeable. At this point it was possible to realize that degradation by a hydrolytic attack was happening by layers and in a linear pattern. Further on, after 72h, a visible release of pigment, as well as empty spaces in the central layer and a frayed pattern on the periphery of the thread are seen, with disorganization of fibrils, breakage of molecules and loss of mass. (4) The degradation seems to happen from the periphery to the center, causing small cracks and allowing water to diffuse into the center. (4, 19) As this process goes on, the heart of the thread is more and more exposed to the extracellular water, and it reaches an acute phase of degradation. It is then mentioned that the total loss of resistance was achieved at day 63. (4, 20) This study shows that, from the biochemical point of view, hyaluronic acid, being highly hydrophilic is a powerful catalyst of PDO threads, degradable by hydrolysis. (4, 21)
In addition, a case report of a patient with complications after insertion of spiculated PDO threads, showing symptoms such as “oedematous erythema, intraepidermal oedema, and ecchymosis at the ends of the thread”. The thread was palpable and originating skin folds. There was increased skin temperature, sore on palpation and an “exanthematous or diffuse erythematous macular basic lesion”. Patient was diagnosed with dermatosis with no signs of infection. It was decided to infiltrate the area with 0,5mL of hyaluronic acid using a canula as an alternative to surgically remove the thread. The goal was to quickly degrade the thread y hydrolysis and fix the aesthetic and inflammatory complication of the initial procedure. The patient was already taking non-steroidal anti-inflammatory drugs and she was advised to continue them for 3 days longer. The procedure was done 24h after the complications of the spiculated threads’ implantation occurred and it was repeated after 21 and 45 days. The patient follow-up at 21 days positively showed improvements, with reduction of oedema and at 45 days with visibly less skin folds and irregularities. The case report shows that this strategy was adequate and successful at solving this complication, with a double win of accelerating the biodegradation of threads and helping to regenerate the tissue around the threads. (5)
4. Conclusion
As the demand for aesthetic medicine procedure increase, the information and research about techniques and materials used also increase. This allows us to be wiser when evaluating the needs of a patient and to plan an efficient strategy of treatment.
The possibilities available are numerous and, in many cases, satisfying a patient and correspond to their expectations is demanding. For a good outcome, it is often needed, not to perform a single procedure, but to opt for a combination of methods to make sure the best result possible is obtained.
PDO threads, as well as hyaluronic acid fillers are widely known in the aesthetic medicine field and are likely to be used in several situations to fight aging consequences. In this study, the goal was to prove the hypothesis that PDO threads and hyaluronic acid fillers shouldn’t be used together in the same facial areas, as simultaneous procedures for treatment approach. This is because, as it was proven by case reports and experiments, hyaluronic acid is a highly hydrophilic substance, inducting the captivity of water to the areas where it was injected and so, becoming, a potent catalyst for biodegradation of the PDO threads’ polymers, which are disrupted through hydrolysis. When inserted in the same areas, and especially in the case where they are inserted in the same skin layers, hyaluronic acid will speed up the degradation of the threads and the more reticulated it is, the higher the water retention. This means that both treatments, when done at the same time, will be counterproductive. As it is known, the procedures in aesthetic medicine are expensive and so, it is necessary that scientific knowledge is used in our favor, to provide good results and potentiate at a maximum level what these products can offer. No complication comes necessarily out of this combination, the problem is that we would be diminishing the potential of a product, using another one.
On the other hand, as shown in the analyzed case study, this information can be used productively, as we’re also facing a solution for complications of PDO threads implantation, since it will accelerate its degradation and allow the caused problems (aesthetic or symptomatic) to be fixed quicker.
This is a literal case in which one information can be used in a positive and in a negative way. Positive to help fixing complication when we need PDO threads to dissolve faster and negative when we combine two products which don’t add up together.
It is up to us to always find the best strategy for our patients, so that products and techniques are combined through a smart, efficient and scientifically based approach.
Tables
Table 1: Filler Procedure, Target Facial Layer Injected, and Type of HA Filler Used retrieved from “Kapoor KM, Saputra DI, Porter CE, et al. Treating Aging Changes of Facial Anatomical Layers with Hyaluronic Acid Fillers. Clin Cosmet Investig Dermatol. 2021;14:1105-1118. Published 2021 Aug 26. doi:10.2147/CCID.S294812”
2From now on stated as PDO
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1Master of Aesthetic Medicine in AMIR, UDIMA (Universidad a Distancia de Madrid)