Clinical Validation of the Surface Volume Coefficient for Minimally Invasive Treatment of the Temple

June 2019 | Volume 18 | Issue 6 | Original Article | 533 | Copyright © June 2019

Sebastian Cotofana MD PhD,a,f Konstantin Koban,b Tatjana Pavicic MD,c Mariya Yankonva,c Konstantin Frank MD,b Jeremy B. Green MD,d Robert H. Gotkin MD,e Lukas Etzel,b Riccardo E. Giunta PhD MD,b Thilo L. Schenck MD PhDb

aDepartment of Medical Education, Albany Medical College, Albany, NY bDepartment for Hand, Plastic and Aesthetic Surgery, Ludwig – Maximilian University Munich, Germany cPrivate Practice, Munich, Germany dSkin Associates of South Florida, Coral Gables, FL ePrivate Practice, New York City, NY fDivision of Plastic Surgery, Department of Surgery, Albany Medical Center, Albany, NY

Abstract
Objective: The aim of the present study is to compare the temporal surface volume coefficient obtained in the cadaveric model from subdermal and supraperiosteal injections to the clinical setting when treating temporal hollowing.

Material and Methods: A total of 36 subjects were included in this investigation, 17 patients (16 females, 1 male; 46.3 ± 8.9 years; 25.5 ± 2.8 kg/m2) and 19 cadaveric specimens (11 females, 8 males; 76.4 ± 11.5 years; 24.0 ± 5.1 kg/m2). Subdermal and supraperiosteal injections were performed and live subjects were evaluated and followed for 12 months. The surface volume coefficients were calculated using 3D surface volume scanning and compared for validity.

Results: No statistically significant difference was detected between the clinical outcome scores of the subdermal vs supraperiosteal injection technique. The supraperiosteal injection technique utilized significantly more product 1.20 ± 0.5 cc [range: 0.50 – 2.6 cc] compared to the subdermal 0.71 ± 0.2 cc [range: 0.30 – 1.20 cc] vs with P< 0.001. This difference was consistent with the different values of the cadaveric surface volume coefficient (subdermal vs supraperiosteal): 1.00 ± 0.2 vs 0.70 ± 0.2. At 12-month follow-up, the product loss was 19% for the subdermal injection and 21% for patients treated with supraperiosteal injections.

Conclusion: The results of the study support the clinical validity of the surface volume coefficient. They demonstrate that the different injection volumes necessary to deliver aesthetically appealing results when utilizing the subdermal vs the supraperiosteal technique can be explained by the region-specific surface volume coefficient.

J Drugs Dermatol. 2019;18(6):533-540.

INTRODUCTION

Facial aging is a multi-factorial process resulting in a range of physiologic and morphologic changes in both the hard and soft tissues of the face – the bones, ligaments, muscles, fasciae, subcutaneous fat, and skin.1,6 The use of soft-tissue filler injections to address the signs of facial aging has increased according to a statistical survey by the American Society of Plastic Surgeons. Between the years 2000 and 2017, the number of soft tissue filler procedures increased by 312%.7

Soft tissue fillers are frequently utilized to restore the age-related loss of soft tissue volume of the face.8-10 Recent studies have indicated that depending on the targeted layer, various aesthetic outcomes can be expected.11 Injections into the subdermal plane ie, into the superficial facial fat compartments, can result in better surface projection when compared to placing the product in the supraperiosteal plane ie, into the deep facial fat compartments and vice versa, depending on the targeted facial region. A measure for estimating this region-specific effect wasrecently introduced and termed the surface volume coefficient (SVC).11 The SVC is calculated by dividing the absolute change in scanned 3D surface projection (cc) by the amount of injected volume (cc) and provides information on the surface effect of a certain amount of injected volume, which could thus be considered the clinical effectiveness of an injected material.

Temporal volume loss can be treated via the injection of soft tissue filler into the subdermal or supraperiosteal plane while respecting regional danger zones. These danger zones are located in Layer 3 (location of the anterior branch of the superficial temporal artery), Layer 4 (intra-fascial plane; location of the motor branches of the facial nerve), Layer 6 (location of the medial zygomatico-temporal (sentinel) vein), and Layer 10 (location of the anterior and posterior deep temporal arteries). Positioning of the product thus needs to be carefully evaluated and balanced weighing safety primarily while considering aesthetic outcome. Injecting the material into the subdermal