Thinning: The Difference between Free and Propeller Perforator Flaps

Dear Sir,

We read with great interest the manuscript by Prasetyono et al. [1] titled "Practical considerations for perforator flap thinning procedures revisited". We want to discuss some points related to this article and highlight some differences between thinning a free perforator flap versus a propeller perforator flap.

We absolutely agree with the authors regarding the possibility of thinning (or defatting) a flap in which the perforators are generally central, but when the perforators are lateralized we believe that the problem is completely different. Indeed, free perforator flaps are most frequently harvested with centralized perforating vessels on the skin paddle, unlike propeller perforator flaps, in which the perforators are lateralized, because of the necessity of rotation.

We often achieve significant thinning of our free perforator flaps without necrosis or any skin suffering. However, thinning our propellers flaps is often more hazardous and sometimes results in extensive unexplained skin problems.

Therefore, we prospectively compared five tibial posterior perforator flaps harvested with suprafascial dissection including distal 2/3 thinning (in the subcutaneous plane) of the flap and five harvested with subfascial dissection without thinning. The size and rotation were similar; i.e., 4×12±2 cm with a twist between 120° and 180°. We noted almost no distal suffering in the subfascial group versus distal problems of 10%-20% for three flaps in the suprafascial group. Moreover, all of the flaps harvested in the suprafascial plane and thinned had an initial venous congestion phase greater and more worrying than did the flaps harvested with subfascial dissection.

We believe that the problem of thinning is more venous than arterial. Thinning alters the arterial vasculature little as the dermal plexus is respected, as explained by Hong et al. [2], but it could reduce venous back flow.

We selected the posterior tibial perforating flap because it is clear that venous problems are much more common in the limbs, and especially the leg, than in the trunk.

Regarding the article by Prasetyono et al., we note some signs of venous suffering at the edge of anterolateral thigh perforator in Fig. 5C and D; these are almost never seen in practice with this flap, which remains very reliable and reproducible. Therefore, the extensive thinning was probably involved in this phenomenon.

In conclusion, perhaps the main problem with thinning is not an impaired arterial supply, but venous back flow, as the subdermal plexus is preserved. If it appears less risky for free perforator flaps or when the perforators are centered on the skin paddle, thinning can be harmful when the perforators are lateralized. For the lower limb, it seems best to avoid thinning propeller perforator flaps unless absolutely necessary.