*Article* **Combined versus Single Perforator Propeller Flaps for Reconstruction of Large Soft Tissue Defects: A Retrospective Clinical Study**

**Amir K. Bigdeli 1,2,\* ,† , Oliver Didzun 1,2,†, Benjamin Thomas 1,2 , Leila Harhaus 1,2, Emre Gazyakan 1,2 , Raymund E. Horch <sup>3</sup> and Ulrich Kneser 1,2**


**Abstract:** Sufficient wound closure of large soft tissue defects remains a challenge for reconstructive surgeons. We aimed to investigate whether combined perforator propeller flaps (PPFs) are suitable to expand reconstructive options. Patients undergoing PPF reconstruction surgery between 2008 and 2021 were screened and evaluated retrospectively. Of 86 identified patients, 69 patients received one perforator propeller flap, while 17 patients underwent combined PPF reconstruction with multiple flaps. We chose major complications as our primary outcome and defined those as complications that required additional surgery. Postoperatively, 27 patients (31.4%) suffered major complications. The propeller flap size, the type of intervention as well as the operation time were not associated with a higher risk of major complications. A defect size larger than 100 cm<sup>2</sup> , however, was identified as a significant risk factor for major complications among single PPFs but not among combined PPFs (OR: 2.82, 95% CI: 1.01−8.36; *p* = 0.05 vs. OR: 0.30, 95% CI: 0.02−3.37; *p* = 0.32). In conclusion, combined PPFs proved to be a reliable technique and should be preferred over single PPFs in the reconstruction of large soft tissue defects at the trunk and proximal lower extremity.

**Keywords:** perforator propeller flap; combined perforator propeller flap; microsurgery; soft tissue reconstruction; propeller flap; perforator flap

## **1. Introduction**

Modern reconstructive surgery offers a vast variety of surgical techniques for the reconstruction of soft tissue defects [1,2]. Although free flaps have been established as the standard procedure in the reconstruction of soft tissue defects, regional flaps might be used depending on the size and characteristics of a defect [3]. However, large defects often require complex solutions with multiple flaps or tissue expansion to ensure sufficient wound closure [4,5]. Frequently used combinations consist of muscle flaps, sliding flaps as well as rotation flaps, which are either combined with one another or with a free flap [6,7]. Nevertheless, limitations of regional flaps are due to arc of flap rotation, flap size to defect size ratio, wound infections, and donor-site morbidity while free flaps are limited whenever vessels for anastomosis are insufficient [8]. Furthermore, prior surgeries often lead to significant scarring and, hence, may impede the use of conventional regional flaps.

Since the introduction of perforator propeller flaps (PPFs), they have gained increasing popularity [9,10]. By the definition of the "Tokyo consensus" on propeller flaps, propeller flaps are "island flaps that reach the recipient-site through an axial rotation" [11]. As a

**Citation:** Bigdeli, A.K.; Didzun, O.; Thomas, B.; Harhaus, L.; Gazyakan, E.; Horch, R.E.; Kneser, U. Combined versus Single Perforator Propeller Flaps for Reconstruction of Large Soft Tissue Defects: A Retrospective Clinical Study. *J. Pers. Med.* **2022**, *12*, 41. https://doi.org/10.3390/ jpm12010041

Academic Editors: Hisham Fansa and Jan Philipp Radtke

Received: 27 September 2021 Accepted: 23 December 2021 Published: 4 January 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

combination of a reliable pedicled flap along with low donor-site morbidity, PPFs offer high flexibility and, therefore, have led to versatile use. First employed in the reconstruction of the upper and lower extremity, PPFs have also become an established technique in the reconstruction of soft tissue defects of the trunk [12]. Even though PPFs have shown to be a reliable reconstructive option, there is a gap in the literature regarding the potential advantages associated with using combined PPFs instead of single PPFs (Table 1). This study aims to compare the outcome of single and combined PPFs, to determine the prevalence of complications among both techniques, and to assess the potential use of combined PPFs in the reconstruction of large soft tissue defects.


**Table 1.** Articles <sup>1</sup> reporting the use of combined perforator propeller flaps.

<sup>1</sup> Case reports as well as articles that did not include combined perforator propeller flaps were excluded.

#### **2. Materials and Methods**

#### *2.1. Patients*

Medical records of all patients who received a PPF reconstruction surgery between 2008 and 2021 at the University Clinic of Erlangen Nuremberg and the BG Trauma Center Ludwigshafen were identified and evaluated retrospectively. All surgeries were performed under the senior author's direct supervision. This study was approved by the ethics board of the Friedrich Alexander University of Erlangen Nuremberg (registration number: 21-433- Br) and the local ethic committee of Rhineland-Palatinate (registration number: 2021-16096). Patients who either received single or combined PPF reconstruction with a minimum rotation arc of 45 degrees were included in the study. Combined PPFs were defined as "double PPF" if two perforator propeller flaps were used whereas those combined with any kind of regional flap were assigned to the group of "PPF plus regional flap".

We utilized patients' digital charts to collect data on individual characteristics, flap surgery, risk factors as well as postoperative complications. Risk factors considered were diabetes, arterial hypertension, peripheral artery disease, coronary heart disease, coagulation disorders, prior thrombotic events, obesity (BMI > 30 kg/m<sup>2</sup> ), radiation therapy, chemotherapy, and smoking. All risk factors as well as postoperative complications were assessed separately before creating a dichotomous variable. Furthermore, postoperative complications requiring surgical treatment were considered as a "major complication" whereas those manageable by conservative therapy were considered as a "minor complication". Partial flap loss was defined as a flap necrosis of at least five percent, which did not result in a total flap removal, while "total flap loss" was defined as a flap loss of more than 50 percent leading to reconstructive failure and, thus, total removal of the flap. Additionally, we recorded the total time of hospitalization as well as the total amount of surgeries related to the specific type of PPF reconstruction surgery (single or combined PPF). We chose "major complication" as the primary outcome variable since, by definition, all kinds of major complications resulted in additional surgeries and, hence, a more complex course of disease.
