Intraarterial Degradation of Calcium Hydroxylapatite Using Sodium Thiosulfate - An In Vitro and Cadaveric Study.

BACKGROUND: The most severe complications following soft tissue filler injections result from the intraarterial administration of the filler product. Although hyaluronic acid-based filler can be trans-arterially dissolved with hyaluronidase, no information is available on calcium hydroxylapatite (CaHA)-based fillers. OBJECTIVE: The authors sought to test whether CaHA-based fillers can be trans-arterially dissolved by sodium thiosulfate (STS) when evaluated in cadaveric and in vitro models. METHODS: Human cadaveric facial arterial segments were each filled with 0.2 cc of commercially available CaHA product and submerged for 24 hours in 4 different STS-containing solutions: 10 cc STS (300 mg/cc) (pure, 1:1 dilution, 1:2 dilution), 0.9% saline and 10 cc STS (300 mg/cc), and 300 IU (bovine) hyaluronidase in a 1:1 ratio. RESULTS: Intraarterial CaHA was detected in human facial artery segments after 24 hours independent of the STS concentration employed. Submerging the arterial segments in STS (300 mg/cc) and 300 IU (bovine) hyaluronidase (1:1 ratio) also did not dissolve the intraarterial CaHA product. Gray scale analyses did show, however, that increasing concentrations of STS resulted in increased disintegration of CaHA in an in vitro experimental setting. CONCLUSIONS: The results of this study indicate that STS is limited in its potential to dissolve intraarterial CaHA of cadaveric human facial arteries, despite the fact that it appears effective when in direct contact with the CaHA. Adverse events caused by intraarterial administration of CaHA-based fillers still lack a suitable antidote.

Subperiosteal injections during facial soft tissue filler injections-Is it possible?

BACKGROUND: It can be hypothesized that safety during soft tissue filler injection could be enhanced if the product could be positioned between the periosteum and the bone surface i.e. subperiosteal. AIM: This study investigated the feasibilityof subperiosteal injections. PATIENTS/METHODS: We analysed 126 injection procedures performed in seven Caucasian body donors (4 males, 3 females) with a mean age of 75.29 ± 4.95 years [range: 70 - 87] and a mean body mass index of 23.53 ± 3.96 kg/m2 [range: 16.46 - 32.23]. The injection procedures were performed in the forehead, scalp, zygomatic arch and the mandible bilaterally. Injection procedures were conducted using 25G, 27G and 30G sharp-tip needles (TSK Laboratory, Tochigi, Japan) and at various angles from the bone surface measured with a goniometer: 90 degrees (perpendicular), 45 degrees and 10 degrees (as tangential as possible to bone surface). RESULTS: Cadaveric dissections of the injection sites showed that no product was located deep to the periosteum in any of the investigated regions. This indicates that all performed injection procedures positioned the product superficial to the periosteum (100%) with a zero-success rate of subperiosteal injections. CONCLUSION: In the setting of this cadaveric investigation, despite varying needle size and injection angle, subperiosteal injection could not be achieved. This indicates that the product can spread uncontrolled into more superficial layers yielding an increased risk for adverse aesthetic and vascular events.

Influence of needle size and injection angle on the distribution pattern of facial soft tissue fillers.

BACKGROUND: Soft tissue filler injections are performed using either sharp-tip needles or blunt-tip cannulas. Product can change planes in an uncontrolled manner during needle injections, potentially leading to unintentional intra-arterial placement. There is a paucity of data on the influence of injection angle on the dispersion patterns of soft tissue fillers. MATERIALS AND METHODS: A total of 126 injection procedures were conducted in seven Caucasian body donors (four males, three females) with a mean age of 75.29 ± 4.95 years and a mean body mass index of 23.53 ± 3.96 kg/m2 . Injection procedures were performed in various facial regions (forehead, scalp, zygomatic arch, mandibular angle), utilizing different needle sizes (25G, 27G, 30G) and different angles (90°, 45°, 10°). Layer-by-layer dissections were performed to verify the location of the injected product. Dissections were facilitated by the colored material. RESULTS: Utilizing a 30G needle (compared to a 25G needle) reduces the superficial spread with OR 0.70 (95% CI, 0.48-0.99) and P = 0.049, whereas injecting at 90° (vs 10° with the bevel down) increases the odds for superficial spread with OR 10.0 (95% CI, 7.11-14.09) and P < 0.001. CONCLUSION: Precision during soft tissue filler injections, defined as the product remaining in the plane of intended implantation, can be enhanced by changing the needle size and the injection angle. Utilizing a 30G needle and injecting at a 10° angle with bevel facing down reduces the uncontrolled product distribution into superficial fascial layers.