Application of chimerical ALT perforator flap with vastus lateralis muscle mass for the reconstruction of oral and submandibular defects after radical resection of tongue carcinoma: a retrospective cohort study

Oral squamous cell carcinoma (OSCC) is one of the most common malignant tumors in the body, with tongue cancer as the most frequently observed type of OSCC. It has been reported that the 5-year survival rate of tongue cancer is about 60%. The incidence rates of mortality and recurrence have increased in recent years due to local recurrence and submandibular cervical lymph node metastasis [1‐3]. Therefore, it is an important challenge for surgeons to develop reasonable surgical treatment strategies, including therapeutic resection, postoperative defect reconstruction, and functional restoration.

Treatment with surgical resection, adjuvant radiotherapy, and chemotherapy are the main therapeutic strategies for the tongue carcinoma. The purpose of surgical treatment is to excise the primary tumor with a wide margin. The tongue is a complex organ which is composed of striated muscles. The tumor cells often migrate from the primary site, infiltrate into the muscle, and develop into local recurrences in the mouth floor and submandibular region. Because of the special anatomical features of the tongue, patients with tongue carcinoma often experience early lymph node metastasis [4‐6]. Therefore, the thoroughness of the resection in the case of tongue cancer is of particularly importance. It has been recently suggested that the upper lingual muscle groups, such as the genioglossus muscle, geniohyoid muscle, mylohyoid muscle, and/or anterior belly of digastric muscle should also be resected in the radical resection to reduce the possibility of recurrence [5, 7, 8]. However, defects in the mouth floor and submandibular region post-operation result in the creation of a large unused space, leading to complications such as submandibular wound infection and oral fistula, thereby prolonging the recovery period of the patients and seriously affecting their prognosis [7, 9].

It is challenging to reconstruct the oral and submandibular defects simultaneously [10, 11]. In recent decades, free anterolateral thigh flap (ALT) has become one of the main choices for reconstruction due to its high reliability and versatility [11]. The traditional ALT carries redundant subcutaneous tissue, fascia lata, and muscle, with a high volume of tissue volume that is far beyond the needs of the surgery. As a result, the perforator ALT flap was developed. The vascular pedicle was skeletonized to obtain the ideal length and to avoid the use of redundant amounts of tissue, which allowed for the accurate repair of the primary oral defect [12‐15]. However, the defect of submandibular region is left unfilled, which may lead to the infection and depression of the submandibular region. To address these shortcomings, the perforator-based chimeric flap with a muscle component has been applied in the reconstruction of complex extremity defects [16]. However, it has not yet been used for the reconstruction of both the oral and submandibular defects after radical resection of tongue cancer.

In this retrospective cohort study, the flap survival rate, the duration of flap harvesting, the incidence of submandibular infection, and lateral appearance were compared between two groups treated with different reconstruction methods. The first group underwent reconstructive therapy with a classical perforator ALT flap, while the other group underwent reconstructive therapy with the chimeric perforator ALT flap, with the muscle mass at the end of the descending branch of the lateral circumflex femoral artery (LCFA).

In this retrospective cohort study, we compared the postoperative outcome and complications between the patients reconstructed with the classical ALT perforator flap and the patients reconstructed with a chimeric ALT perforator flap with vastus lateralis muscle mass. The results showed that the infection rate was reduced and the submandibular fullness was satisfactory in the chimeric group.

The process of lymphatic drainage of tongue tissue is rich and complex [1]. Lymphatic fluid first concentrates in the floor of the mouth and is then transferred into the upper cervical lymph nodes [2]. Tumor cells move downwards, along the path of least resistance [22]. The metastasis of the lymph nodes of the floor of the mouth is difficult to observe and diagnose [4]. As a result, it has been proposed that the radical dissection of tongue cancer should contain both the primary lesions and possible pathways of metastasis, including the partial suprahyoid muscle groups and the lymphatic, neurovascular, and glandular tissues [5, 7, 8]. In this study, we resected the primary lesions and partial suprahyoid muscle groups in all cases. However, as a result, an extensive empty space in the floor of the mouth and submandibular region was left.

The reconstruction of both the primary site and the floor of the mouth for tongue cancer patients is a challenge for surgeons. The anterolateral thigh flap (ALT) has been used for reconstruction in tongue cancer patients for several decades [8, 12, 13]. However, perforators are not dissected through vastus lateralis muscle in the traditional ALT flap and thus the muscle and overlying skin are generally harvested as a single, large section [12, 13]. Because of the poor flexibility of the traditional ALT flap, the shape of the reconstructed tongue is generally unsatisfactory. In this study, the perforator was dissected through the muscle, and the vastus lateralis muscle component was carried in the distal runoff of the descending branch of LCFA in the chimeric group [23]. We found that the chimeric perforator ALT flap with a muscle component was suitable for most cases of tongue cancer, with the following advantages: (1) The damage of donor site is reduced as much as possible because both the flap and muscle component are harvested precisely according to the size of oral and submandibular defects, which obeys the principle of “economy of donor site incisions” [16, 24]; (2) The distance between the perforator of the flap and the muscle component is about 3–5 cm, which provides a greater degree of freedom to inset the muscle mass [23, 25].

The perforator-based chimeric flap has been used in the reconstruction of extensive extremity defects with a deep and slender dead space [23]. Recently, it has also been used in complex or multiple defects in the head and neck region [26]. For example, Lai et al. [27] used the chimeric ALT flap to reconstruct the complete loss of upper and lower lips. Zeng et al. [28] used the chimeric ALT perforator flap to reconstruct the complex total parotidectomy defect. Jiang et al. [29] used multipaddled ALT flaps to reconstruct multiple oral defects. However, this study is the first to report on the application of the chimeric ALT perforator flap with a muscle component after the radical resection of tongue cancer. We found that the chimeric ALT perforator flap could be used to significantly reduce the incidence of wound infection, shorten the time of wound healing, and obtain a better submandibular appearance.

In this retrospective study, the factors of HBP and the types of flap used were found to have a significant effect on the rate of wound infection, using both univariate and multivariate analyses. However, other risk factors, including smoking, betel nut consumption, and diabetes, were only found to be significant in the univariate analysis, and not in the multivariate analysis, which may result from an insufficient sample size. Therefore, a prospective case-control study with a larger sample size will be needed to verify our findings.

The chimerical ALT perforator flap with vastus lateralis muscle mass can be used to accurately and safely reconstruct both oral and submandibular defects. This type of perforator flap maintains the profile and fullness of the submandibular region and may reduce the incidence of submandibular infection.