**1. Introduction**

Deep sternal wound infection (DSWI) after cardiac surgery is a severe complication that can result in devastating mortality rates between 10 and 47% [1,2]. Among these

**Citation:** Bigdeli, A.K.; Falkner, F.; Thomas, B.; Hundeshagen, G.; Mayer, S.A.; Risse, E.-M.; Harhaus, L.; Gazyakan, E.; Kneser, U.; Radu, C.A. The Free Myocutaneous Tensor Fasciae Latae Flap—A Workhorse Flap for Sternal Defect Reconstruction: A Single-Center Experience. *J. Pers. Med.* **2022**, *12*, 427. https://doi.org/10.3390/ jpm12030427

Academic Editors: Andreas Arkudas and Raymund E. Horch

Received: 1 February 2022 Accepted: 7 March 2022 Published: 9 March 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/).

multimorbid patients, who often not only bear the burden of pre-existing coronary artery disease (CAD), but also chronic obstructive pulmonary disease (COPD) and diabetes mellitus (DM), reconstructive procedures are highly challenging [2]. The treatment of DSWIs requires radical surgical debridement of soft and bony tissue and, eventually, tension-free defect closure with well-perfused tissue [3]. For sternal defect reconstruction, microsurgeons have a vast armamentarium of pedicled and free flaps at their disposal: Common reconstructive options for sternal defect reconstruction are local flaps from the chest, abdomen, or the back, such as the vertical rectus abdominis musculocutaneous (VRAM) flap, the pectoralis major, and the latissimus dorsi (LD) flap [4,5]. When both internal mammary arteries (IMAs) have been harvested for coronary-artery bypass grafts (CABG) or after previous local flap failure, reconstruction can be difficult. This is partially due to the fact that the arc of rotation of pedicled flaps is limited [5,6] and closure of defects, which include the entirety of the sternum, can be critical, putting the most distal part of the pedicled flap at risk of impaired perfusion [7,8]. To offer these multimorbid patients the best possible care and optimal long-term outcomes, we are increasingly using the free myocutaneous tensor fasciae latae (TFL) flap for extended deep sternal defect reconstruction. With its voluminous muscle bulk and large skin paddle, it can be adapted to large and multilayered wounds, making it ideal for complex sternal reconstruction [9,10]. Here, we report our one-decade single-center experience of 46 free TFL flaps for deep sternal defect reconstruction following cardiac surgery. The study aimed at evaluating the feasibility of this free flap for sternal reconstruction by analyzing operative data, surgical complication rates, reconstructive outcomes, and donor-site morbidity.

#### **2. Patients and Methods**

The study has been performed in accordance with the guidelines and regulations of the Declaration of Helsinki and has been approved by the local ethics committee (Mainz, Germany, IRB approval reference number: 2021–15577). Retrospective clinical data were collected from our institutional database of patients undergoing free flap reconstruction from January 2010 until March 2021. A retrospective chart review for intraoperative details, surgical and medical complications, length of hospitalization, as well as outcome and mortality rates, was performed. The severity of DSWI was rated according to the El Oakley and Wright classification from I to V [11]. The ASA (American Society of Anesthesiologists) classification system was used to assess the perioperative risk for each patient. Postoperative surgical complications, which required additional surgical intervention, were considered as major. The primary outcomes studied were "re-explorations" because of acute vascular complications, such as pedicle thromboses, as well as flap necrosis, wound dehiscence, hematoma, and infection. Partial flap necrosis was considered as necrosis affecting >5% (maximum of 20%) of the flap surface area. In addition, any medical complications, such as respiratory failure or death throughout the postoperative hospital stay, were evaluated.

#### *2.1. Pre-, Intra-, and Postoperative Treatment*

All free TFL flap operations were performed in a two-team approach for the donor- and recipient-sites. Intraoperatively, 500 IU to 1500 IU (international units) of unfractionated heparin were applied prior to releasing the flap anastomosis or 2000 IU to 3000 IU in case of an arteriovenous loop (AVL). Intraoperative flap perfusion measurements were not performed regularly. However, since January 2017, indocyanine green angiography (ICG) has been performed occasionally, depending on the individual intraoperative decision of the senior surgeon. Primary closure of the TFL donor-site was performed in two layers. Closed suction drains were left in situ in all cases. No additional reconstruction of the fascia was performed. Postoperatively, all patients received 30 mg enoxaparin twice a day over a five-day period, followed by daily 40 mg doses for at least two weeks. Subsequently, the therapy was continued until adequate mobilization of the patient was achieved All free flaps were examined hourly by analyzing the capillary refill, skin temperature, and skin color for five days in order to detect any perfusion alterations.

#### *2.2. Follow-Up*

Follow-up was established from the date of surgery to the last outpatient visit at our department at least 3 months after discharge. Follow-up examinations included donor-site range of motion (ROM), with measurements in hip and knee joints, as well as strength measurements of the thigh muscles. Results were analyzed and compared to the contralateral healthy side. Muscle strength was assessed manually and scaled in six grades (0 = complete paralysis, 1 = contraction palpable, 2 = active movement with gravity eliminated, 3 = active movement against gravity, 4 = active movement against resistance, 5 = normal power) [12]. Additionally, each patient completed the Quality of Life 36-item Short Form Health Survey (SF-36) and the Lower Extremity Functional Scale (LEFS) questionnaire [13,14]. The subjective donor-site morbidity and satisfaction with the overall aesthetic and functional results were analyzed using a self-reported non-standardized 6 point Likert-questionnaire. Results were rated on a scale from 1 to 6 (1 = excellent, 6 = poor). The Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scales (POSAS) were used to analyze scarring at the donor- and recipient-sites [15,16].
