Abstract
The objective was to describe the utility of the chimeric posterior tibial artery flap (CPTAF) in the restoration of compound defects in the oral and maxillofacial region. Patients who underwent head and neck reconstruction using a CPTAF between February 2018 and February 2019 were included. Special consideration was given to the distribution of septocutaneous perforators (SPs), indications, flap survival, and complications. Nine patients were included. All flaps survived. One patient developed a surgical site infection, which was managed conservatively. The CPTAF was raised as a bipaddle skin flap without muscle ( n = 1), with the gastrocnemius muscle ( n = 6), or with the soleus muscle ( n = 2). The number of SPs ranged from three to five (mean 4 ± 0.8). The SPs were mostly located between 4 cm and 20 cm proximal to the medial malleolus (mean 9.5 ± 3.8 cm). The skin paddle was used to reconstruct skin or mucosal defects, whereas the muscle part was used to fill the dead space ( n = 7) or to support the orbital contents ( n = 1). The donor site healed with no associated functional complications. The CPTAF is a good option for the restoration of composite tissue defects in the head and neck region. It offers flexibility during flap inset and provides the appropriate bulk to repair defects in multiple planes.
Microsurgical free flaps have become the gold standard for the restoration of head and Chimeric posterior tibial artery flap neck defects after tumour resection . Complex defects involve different structures in the head and neck region, and if not reconstructed appropriately, may result in significant functional and aesthetic morbidity. With the advent of the chimeric flap, a new era in the restoration of complex maxillofacial defects has opened. These flaps have many of the ideal prerequisites for soft and hard tissue replacement, the feasibility to create multiple skin, muscle, and bone paddles linked together to a single main vascular pedicle, offer flexibility during flap inset, and provide the appropriate bulk to repair defects in multiple planes.
Hallock classified chimeric flaps into two types based on the relationship between the supply vessels and the main trunk: perforator-based chimeric flaps and branch-based chimeric flaps .
The posterior tibial artery flap (PTAF) was described by Zhang et al. in 1983 as a medial leg skin flap . This flap gained extensive popularity, especially for reconstruction of the lower extremities . In 1990, Chen et al. were the first to use the PTAF in the head and neck region for the reconstruction of the entire oesophagus after a corrosive injury . Since then, few studies have been published on its use for head and neck reconstruction .
The PTAF shares many similarities with the radial forearm flap (RFF). It has a thin and pliable skin paddle, a long pedicle with large vascular calibre, a constant and reliable anatomy, and the feasibility of a simultaneous two-team approach. Additionally, the PTAF leaves a less conspicuous and well-hidden postoperative scar in the lower extremity. Although the thinness of the RFF and PTAF has been considered an advantage for the reconstruction of particular defects, it has also been regarded as a limitation when a thick flap is needed. Thus, it would be a significant improvement if the volume of the PTAF could be adjusted via the inclusion of other structures, in order to meet the requirements for the restoration of compound defects involving different structures in the oral and maxillofacial region. The aim of this study was to describe different types of chimeric flap deriving their blood supply from the posterior tibial artery, which were used for the repair of compound defects in the oral and maxillofacial region.
Patients and methods
Patients who underwent reconstruction in the oral and maxillofacial region using a chimeric posterior tibial artery flap (CPTAF) in the Department of Oral and Maxillofacial, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, from February 2018 to February 2019, were included. This study was approved by the Institutional Review Board of Sun Yat-sen Memorial Hospital, Sun Yat-sen University. An informed consent agreement was provided by all patients recruited.
Patients were excluded if they had any pre-existing vascular, neurological, or orthopaedic pathology in their lower extremities. All included patients were assessed preoperatively, intraoperatively, and postoperatively. The preoperative assessment included age, sex, and the leg to be used. The lower limb vessels were evaluated using computed tomography angiography (CTA). The pulses of the anterior tibial, posterior tibial, and dorsalis pedis arteries were confirmed by digital palpation. Intraoperative assessments included flap diameter and thickness, pedicle length, number and position of septocutaneous perforators (SPs), the calibre of the posterior tibial vessels, and operative difficulty. Postoperative data collected included the flap survival rate and donor site morbidity.
Surgical technique
All flaps were harvested by the first author (M.A.M.). The flaps were raised under tourniquet control. After appropriate evaluation of the tumour size, the required diameter of the skin island of the flap was outlined on the medial leg approximately 3–4 cm proximal to the most prominent bony area of the medial malleolus. The flap harvesting was initiated at the tibial aspect and in a subcutaneous plane above the tibial bone. The long saphenous vein was sometimes encountered; this was ligated and incorporated with the flap or it was preserved. The harvesting continued until it reached over the flexor digitorum longus muscle, then the crural fascia was incised and retracted posteriorly to expose the cutaneous perforators ( Fig. 1 ).
Once the cutaneous perforators had been identified, the CPTAF was adjusted by the inclusion of different structures to meet the requirements for the restoration of a compound defect. Flap raising was then continued proximally until it reached over the medial gastrocnemius muscle. Once harvesting had reached over the gastrocnemius muscle, the perforator from the posterior tibial artery to the gastrocnemius muscle was identified and preserved ( Fig. 2 ). However, in cases where there was no sizeable perforator supplying the gastrocnemius muscle, the soleus muscle was raised with the flap. In the case of a through-and-through defect, a bipaddle chimeric skin flap was raised. The posterior tibial vascular pedicle was then carefully separated from the posterior tibial nerve and divided distally. Afterwards, harvesting was continued along the vascular pedicle, and any vascular branches other than the perforators of the skin or muscular parts of the CPTAF were dissected and ligated or cauterized depending on the size. Once the required length of the vascular pedicle was achieved, the pedicle was divided.
Next, a full thickness triangular skin graft was harvested just proximal to the skin island and used to close the donor site defect ( Fig. 3 ). The triangular full thickness skin graft was used to repair the distal defect side, whereas the defect proximal to the narrow vertex of the triangular full thickness skin graft was closed primarily ( Fig. 3 ). Finally, a bolster dressing was applied for 2 weeks.
Statistical analysis
Descriptive data are reported as the mean ± standard deviation (SD) or as the frequency and percentage, as appropriate. All statistical analyses were conducted using GraphPad Prism version 6.0 for Windows (GraphPad Inc., San Diego, CA, USA).
Results
Nine patients were included in this study. All patients were male and their average age was 54.5 years ( Table 1 ). Two patients had undergone prior surgeries in the head and neck area.
| Patient number | Age (years), sex | Tumour location | TNM staging | Number of SP | Type of chimeric flap | Complications | Follow-up, months |
|---|---|---|---|---|---|---|---|
| 1 | 64, M | L oronasofacial | T3N0M0 melanoma | 5 | Gastrocnemius muscle | No | 15 |
| 2 | 60, M | L tongue | T3N1M0 SCC | 4 | Gastrocnemius muscle | No | 15 |
| 3 | 69, M | R tongue | T4N1M0 SCC | 5 | Gastrocnemius muscle | No | 12 |
| 4 | 39, M | L maxilla and soft palate | T3N1M0,SCC | 3 | Gastrocnemius muscle | No | 12 |
| 5 | 46, M | Bilateral FOM | T4N0M0 ACC | 5 | Gastrocnemius muscle | SSI | 3 |
| 6 | 52, M | L tongue | T3N1M0 SCC | 4 | Soleus muscle | No | 3 |
| 7 | 42, M | Bilateral FOM and tongue | T4N0M0 ACC | 3 | Soleus muscle | No | 6 |
| 8 | 64, M | R tongue | T4N1M0 SCC | 4 | Gastrocnemius muscle | No | 6 |
| 9 | 62, M | R buccal mucosa | T3N1M0 SCC | 3 | Bipaddle skin | No | 2 |
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