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Ciclamini et al. Plast Aesthet Res 2023;10:62 https://dx.doi.org/10.20517/2347-9264.2022.132 Page 7 of 10

surface. Furthermore, interaction with the surrounding environment needs highly coordinated actions of a
mobile and sensitive hand. Consequently, soft tissue injuries of the hand represent a more difficult
reconstructive challenge for the surgeon than similar injuries elsewhere [19-21] - one of the main reasons for
such a problematic condition is the need for thin tissue to wrap the superficial noble structures of the hand.
Knowledge of vascular anatomy is fundamental to achieving this goal. Its development has inevitably led to
innovations in flap design and clinical application, enabling improved aesthetic and functional results that
today go beyond simply filling the defective area. The evolution of the flaps has followed a linear
progression, primarily due to the pioneering studies of vascular anatomy [22-29] - flap thinning techniques rely
on a deep and accurate knowledge of the most superficial vasculature of flaps.

Several thin loco-regional and free flaps are suitable for covering the hand, such as the cross-finger flap, kite
flap, dorsal metacarpal artery flap, pedicled radial forearm flap, pedicled medial arm flap, pedicled and free
posterior interosseous flap, medial plantar flap, and lateral arm fascia flap with a skin graft [30-32] .
Unfortunately, other flaps with thick subcutaneous tissues are too bulky for upper-limb reconstruction.
Nevertheless, many large and bulky flaps sometimes represent an inevitable choice in case of significant size
defects. The flap-thinning technique was introduced in the 1960s to address this problem. Since then, this
technique has been the focus of much attention and is still undergoing continuous evolution. However,
secondary debulking procedures (fatty layer direct excision or liposuction some months after the first
surgery) are still widespread. Some drawbacks include additional costs, impaired vascularization of the
subdermal plexus, and multiple surgical stages.

A combination of improvements in surgical techniques and an appropriate description of the anatomy of
the vascularization of flaps led to the elevation of a thinner flap in one stage. The flap can be harvested
thinly from the beginning of the procedure by modifying the dissection plane or, once harvested, can be
thinned through the removal of fat located at the superficial or deep fascial level. However, this procedure
can be dangerous if performed without understanding the basic vasculature of the flap. Nakajima et al., in
1998 , performed a three-dimensional analysis of the integument to understand this anatomy better. They
[28]
divided the integument into three different layers: the deep and superficial adipofascial layer, below and
above the superficial fascia, respectively, and the dermis. Based on this division of the skin, they classified
the vascularisation of the skin and, consequently, the skin flaps into six types, providing basic knowledge
about the characteristics of each type of flap and the method of defatting. Flaps with type IV (thoracodorsal
artery, thoracoacromial artery, and deep inferior epigastric artery) and VI (perforators of the latissimus
[28]
dorsi and gluteus maximus muscles) vasculature are ideal for flap thinning, according to Nakajima and
Park . In this study, it appears that the DIEP flap can be thinned more effectively than, for example, the
[33]
most discussed ALT flap, categorized as type III. However, many studies describe the harvest of even ultra-
thin ALT flaps, but mainly from Asian countries . Following cadaveric studies, some Authors do not
[34]
suggest one-stage thinning of the ALT flap in the Western population, as this could lead to ischemia and
skin necrosis (CIT).
[35]
Since flap thinning began to be discussed, there has been confusion over the terminology used to talk about
thin and super-thin flaps. There is no consensus regarding the definition of these terms in the literature. In
2021, Rios et al. proposed a classification to provide a better understanding of the concepts [Table 3] . In
[36]
[36]
[36]
their literature review about supra-fascial free flaps, Rios et al. also underlined the critical importance of
preoperative imaging planning in flaps dissected above the deep or superficial fascia. Identifying a vascular
[38]
pattern by CT-angiography and ultra-high frequency ultrasound preoperatively and hand-held
[37]
acoustic Doppler or duplex ultrasound [37,38] allows us to recognize the perforating vessels in the supra-fascial
plane. This preoperative awareness helps flap harvest, improves flap survival, shortens the operating time,