Assessing the Practical Application of Rheological Properties of Hyaluronic Acid Fillers: A 1-Year Follow-Up Photographic Analysis.

BACKGROUND: A hyaluronic acid filler is a viscoelastic substance that can be evaluated by rheology. Rheological properties are important for the longevity of the filler, which can be deformed due to the various forces that exist on the face. This study aimed to evaluate the maintenance of the lifting capacity of hyaluronic acid filler injection. METHODS: Rheological evaluation of five different products was performed on nine patients who had undergone hyaluronic acid filler injection from Jan 18, 2021 to Jan 27, 2022. Photographs from different time points up to 1 year after filler injection were used to determine the maintenance of the lifting effect of the filler injection. RESULTS: After 1 year of follow-up, the filler on the forehead, temple area, nose, chin, nasojugal fold, and mid-cheek groove areas showed good maintenance, while the nasolabial fold slightly improved. CONCLUSIONS: Appropriate rheological parameters of hyaluronic acid fillers should be considered before injection into different facial areas. A good choice of filler can result in a good aesthetic effect 1 year after injection. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors   www.springer.com/00266 .

Soft Tissue Filler Properties Can Be Altered by a Small-Diameter Needle.

BACKGROUND: Small-bore needles reduce the complications associated with soft tissue filler injection. Gel particles must be sized appropriately to pass through fine-bore needles with an acceptable extrusion force. However, most soft tissue filler particles are larger than the inner diameter of the needle. The authors hypothesized that the physical properties of these particles change as the gel passes through the needle. OBJECTIVE: The authors aimed to investigate whether the predesigned physical and rheological properties of the filler change after passage through the small-bore needle. METHODS AND MATERIALS: Particle sizes of 4 hyaluronic acid (HA) fillers were analyzed using a particle size analyzer. Five soft tissue fillers with different particle sizes were subjected to rheological characterization. All tests were performed using fillers with and without a 30-G needle. RESULTS: Monophasic HA fillers with smaller particle sizes exhibited small changes between particle sizes but no differences in rheological properties. Biphasic HA fillers with larger particle sizes exhibited remarkable changes in particle size and rheological properties. Calcium fillers exhibited changes in rheological properties. CONCLUSION: Injection through small-bore needles can alter the physical properties and rheological equilibrium of soft tissue fillers. The authors suggest avoiding small-bore needles as they may affect the rheological equilibrium and clinical performance of fillers.

Ocular complications of soft tissue filler injections: A review of literature.

BACKGROUND: Soft tissue filler is commonly used for facial contouring. However, incorrect use can lead to severe ocular complications. Even though filler injections are quite different from fat grafts, they are considered similar procedures. However, to date, there are no proven preventive measures or treatments for blindness secondary to soft tissue filler injections. OBJECTIVES: This literature review aimed to investigate visual compromise secondary to soft tissue filler injection and discuss the related vascular anatomy, pathophysiology, and prevention of ocular complications of soft tissue filler injections. METHODS: A literature search until July 2018 was performed for reports on visual compromise after filler injections. We evaluated the previous literature and eliminated cases using fat grafts and unknown fillers. RESULTS: A total of 50 reports of filler-induced visual compromise were identified. Analysis of these cases showed that the procedure with greatest risk was nasal augmentation, followed by glabellar wrinkle treatment. Within the last 3 years searched, 35% of reported cases involved treatment of the nose. There were no reports of blindness from injections into the temple or chin and relatively few case reports involving forehead injections. CONCLUSION: The most common injection site associated with blindness in a previous report was the glabella; however, the most common site currently associated with blindness due to filler injections was the nose. Extreme caution is necessary when performing nasal augmentation or glabellar wrinkle correction using soft tissue fillers to avoid the branches of the internal carotid artery.

Infraorbital groove correction by microfat injection after lower blepharoplasty.

BACKGROUND: Blepharoplasty alone cannot completely correct deep infraorbital grooves because of its limited ability to improve anatomical volume loss. As the concept of resolving periorbital fat atrophy to improve the infraorbital groove was introduced, several methods to properly fill the groove have been attempted. The purpose of this study was to present a new technique, involving the use of autologous fat from periorbital compartments, for infraorbital groove correction after lower blepharoplasty. MATERIALS AND METHODS: Fifty patients (mean age, 55.9 years; range, 41-75 years) underwent transcutaneous lower blepharoplasty between December 2016 and August 2018. Infraorbital septal fat was harvested during the operation; after lower blepharoplasty, transcutaneous microfat was injected into the infraorbital groove. RESULTS: One month after the procedure, 46 patients were satisfied or very satisfied with the results. One patient complained of an unsolved prominent infraorbital groove; additional microfat graft harvesting was performed from the abdomen after 6 months. Two patients complained of remnant septal bulging; additional transconjunctival fat was removed after 6 months. Five patients developed mild ectropion and recovered without any additional treatments. None of the patients developed infection, hematoma, lid retraction or any other complications. CONCLUSIONS: Microfat injection after lower blepharoplasty has become popular. The method described in this study has certain advantages: the amount of correction is accurate, there is no donor-site morbidity and both subcutaneous and submuscular layers can be corrected simultaneously.

Nasal dorsum augmentation using soft tissue filler injection.

BACKGROUND: Soft tissue filler injection is a common procedure for augmentation rhinoplasty. Various techniques for augmenting the nasal dorsum using a soft tissue filler have been attempted considering the size of the needle, the anatomical layer where the filler is injected, and the vascular distribution. The purpose of this paper was to evaluate the course of the dorsal nasal artery in patients scheduled for nasal augmentation using a soft tissue filler and to propose a method of nasal augmentation that minimizes vessel damage during soft tissue filler injection by confirming the distribution pattern of blood vessels through ultrasound. METHODS: Patients underwent augmentation rhinoplasty using a soft tissue filler. All patients underwent ultrasound examination before the filler injections. RESULTS: From July to September 2018, ultrasound studies were conducted before augmentation rhinoplasty in 50 consecutive patients. Forty patients (80%) had a well-known lateral arterial pathway, while in 10 patients (20%), the dorsal nasal artery was found at the midline of the nose. In four cases (8%), the artery travelled just beneath the preperiosteal layer, which is under the nasalis muscle. Additionally, in seven cases (14%), the dorsal nasal artery coursed superficially, just beneath the subdermal layer. CONCLUSION: Injecting the filler into the preperiosteal layer either via a needle or cannula is considered relatively safe but there remains the possibility of vascular compromise. Using a large diameter cannula and injecting the filler into the preperiosteal layer using a gentle approach may be the safest approach.