in the incidence of papule formation was observed with their
implementation (Figures 1 and 2).3,9,11,14,16,18,19,22,23,26-36
Two groups of investigators have reported on the impact of a
methodology modification on the incidence of subcutaneous
papules in their own practices.12,25 In the first report, which included
observations on approximately 300 patients across a
5-year period, PLLA was reconstituted in 3 mL sterile water and
hydrated for 2 to 12 hours prior to injection in the first 2 years
of observation.12 With this protocol, 10% of patients developed
subcutaneous papules, the majority of which resolved in 12 to 24
months without treatment. The protocol was modified about halfway
into the 5-year period, in which 3 key methodological factors
were altered: hydration time was increased to 36 to 48 hours, 2
mL lidocaine was added to the suspension immediately before
injection (for a total volume of 5 mL), and PLLA was injected into
the uppermost portion of the subcutaneous fat rather than the
lower dermis. With these protocol modifications in place, the incidence
of subcutaneous papules decreased to <1%.12
The second group of investigators injected approximately 3,000
patients with PLLA from 1999 to 2006, using a micropuncture
technique.25 From 1999 to 2002, about 1,500 patients received
injections in which PLLA was reconstituted in 3 mL sterile water,
with an incidence of late-onset inflammatory nodules of
1%. In the latter 4 years of this time period, the reconstitution
volume was increased to 5 mL (or even greater, on occasion),
with the other methodological factors held constant. In this second
cohort of approximately 1,500 patients, the incidence of
late-onset nodules was greatly reduced to 0.13%.25
Our understanding of how best clinically to use PLLA continues to
evolve based on clinical trials and real-world experience, as well
as through a deeper appreciation of the interplay between facial
structures throughout the aging process. These advancements
have enabled more subtle distinctions to be made regarding the
use of PLLA, such as injection techniques for specific facial areas,
and the correlations between treated surface area and per-session
product volume and between the volumetric correction and
number of sessions required.37 These and other more nuanced observations
will be more specifically described in the “Consensus
Recommendations on the Use of Injectable Poly-L-Lactic Acid for
Facial and Nonfacial Volumization†section of this supplement.38
