Soft Tissue Defects of Neck and Shoulder Managed by Pedicled Latissimus Dorsi Myocutaneous Flap Transthoracic Transposition

Background


Results
Seven cases obtained direct healed without signi cant complications. Four cases developed postoperative infections at the distal ends of the skin aps, and they were successfully treated by antiinfection treatment and repeated dressing changes. All patients were regularly followed up with an average of 17.3±3.8 months, satisfactory results with good ap blood supply and limb function were achieved in all patients, and no recurrence of infection was observed.

Conclusions
PLDMF is a practically alternative treatment for the reconstruction of soft tissue defects combined with infection in neck and shoulder, including advantages of high survival rate, satisfactory functional recovery, and clinical practicality. However, surgical indications should be taken into account due to the inferior aesthetic appearance, especially for young female.

Background
Latissimus dorsi myocutaneous ap has been widely used in the reconstruction of adjacent soft tissue defects, including advantages of large donate site with muscle attachments 1, 2 . However, with the development of microsurgery technology, the dorsal thoracic artery perforator ap without latissimus dorsi has achieved better effects due to its thinner cut and less damaged to the donor site 3,4 . Although the pedicled latissimus dorsi myocutaneous ap may lead to more iatrogenic trauma and inferior aesthetic, it still has a relatively reliable effect in the reconstruction of wounds with soft tissue infections in which the expanded debridement is needed 5,6 . The purpose of this study was to evaluate the effectiveness of latissimus dorsi myocutaneous ap in repairing neck and shoulder soft tissue defects combined with infection. This study reported 11 patients with large neck and shoulder soft tissue defects combined with infection. After extensive debridement, the latissimus dorsi myocutaneous ap was applied to cover the defect area to evaluate the clinical effectiveness of this ap in similar injuries.

Methods
A total of 11 patients with neck and shoulder soft tissue defects combined with infection, from July 2017 to December 2019, were treated by pedicled latissimus dorsi myocutaneous ap (PLDMF) in our department. There were 9 males and 2 females with an average age of 40.2±12.6 years. The mechanism of injuries was tra c accident injury in 8 cases, heavy object crush injury in 2 cases, and shoulder tumor resection in 1 case. After debridement of infected and necrotic tissue, the average defect area was (7.0±1.3) cm × (4.8±1.2) cm. According to the shape and size of the soft tissue defect, PLDMF was used to repair the soft tissue defect, and the average area of the ap was (34.4±3.8)cm × (6.0±1.0)cm. The donor site was sutured directly.
The inclusion criterion was the soft tissue defects of neck and shoulder caused by local debridement or tumor resection, which could not be sutured directly. The exclusion criteria were as follows: a. Patients with serious underlying diseases, such as severe heart failure, renal failure, severe hypertension, and diabetes, who could not tolerate long-term surgery; b. Patients with severe infection on the wound surface of the recipient site, without performing thorough debridement and good control of infection; c. Patients with severe extremities vascular sclerosis, which can lead to ap vascular crisis, and thereby seriously affecting the postoperative effect.

Surgical technique
Under general anesthesia, the patient took a left lateral decubitus position with the right upper limb exed on the front chest. Before ap design, ultrasound Doppler was used to explore the perforator branches of the dorsal thoracic artery at the intersection of 6-8cm below the axillary apex and the dorsal thoracic artery. When designing the ap, point A was marked at the apex of the posterior axillary wall, point B was marked at the right posterior superior iliac spine, and the line between point A and point B was the axis of the latissimus dorsi myocutaneous ap.
With the aid of a head-mounted magnifying glass, cut open the frontal edge skin, subcutaneous tissue, and fascia of the designed ap to fully expose the leading edge of the latissimus dorsi , along which the latissimus dorsi was freed and lifted up. Then cut open the posterior edge skin, subcutaneous tissue and fascia of the designed ap, the latissimus dorsi myocutaneous ap was cut off from the distal end of the designed ap, the free latissimus dorsi myocutaneous ap was dissected from the distal end to the proximal end, and then carefully stop bleeding in the wound (Figure 1). At 6-8cm in the axilla, thoracodorsal arteries and veins, and thoracodorsal nerves were seen into the designed myocutaneous ap. Free the myocutaneous ap to the axilla as the rotation point, where the fascia was loosened and the possible compression caused by the rotation of the myocutaneous ap was relieved, the myocutaneous ap was then protected after being wrapped with wet gauze. Full-thickness suture was performed in the donor site of the myocutaneous ap, a rubber tissue was used for drainage, and a sterile dressing was applied.
The patient's position was changed from side lying to supine, with the back of the affected side hand abducted. Firstly, the surface in ammatory granulation, inactivated and necrotic tissue were removed along the wound edge of neck, shoulder and back, and the branches of cephalic vein and external jugular vein were explored and ligated. Then the wound was rinsed repeatedly with hydrogen peroxide and normal saline to provide a good recipient site for the skin ap. Meanwhile, carefully observe the blood supply of the latissimus dorsi myocutaneous ap, cut open the skin and subcutaneous tissue of the axilla and chest, the ap was transferred to cover the wound through the open channel. Then the latissimus dorsi muscle tissue and the soft tissue inside the wound surface were sutured and xed, thereafter the skin around the ap was sutured. There should be no local tension after the ap was sutured and covered, and the wound surface should be well covered. Rubber tissue was placed around the ap for drainage.

Results
Seven cases obtained direct healed without signi cant complications. Four cases developed postoperative infections at the distal ends of the skin aps, and they were successfully treated by antiinfection treatment and repeated dressing changes. All patients were regularly followed up with an average of 17.3±3.8 months, satisfactory results with good ap blood supply and limb function were achieved in all patients, and no recurrence of infection was observed.

Typical case
A 22-year-old male patient suffered an open fracture of the right clavicle combined with soft tissue defects from a car accident. Debridement treatment was performed rstly, and then skin ap transplantation was conducted after the wound infection was controlled and the granulation tissue was well formed. In the second stage, after the removal of excess in ammatory granulation and necrosis tissue, the defect size was measured to be 8cm × 6cm, and the fractured end of clavicle and subclavian vascular pulsation could be seen in the wound. The PLDMF was designed based on the defect size, and clavicle fracture reduction and internal xation were performed at the same time. After 8 months of follow-up, the aps healed well without recurrence of infection, and the fracture achieved union (Figure 2-3).

Discussion
The latissimus dorsi myocutaneous ap is one of the largest skin aps that can be cut in the human body, and can be designed to various types of skin aps, muscle aps, myocutaneous aps, lobed myocutaneous aps and composite myocutaneous aps 7  wound surface reconstruction 3 . Severe neck and shoulder trauma or tumor resection often result in large soft tissue defects, especially in the case of exposed joint. The application of simple free skin ap to cover soft tissue defects is often di cult to meet the requirements for joint function protection and wound healing 8,9 . In contrast, the latissimus dorsi myocutaneous ap can not only meet the needs of soft tissue lling in the neck and shoulders, but also close to the neck and shoulders include advantages of easy shaped, su cient blood supply, and high survival rate 10 .
Patients in this study suffered blood vessels, nerves and bones exposure with severe soft tissue infection.
The use of a pedicled skin ap with latissimus dorsi to cover the soft tissue defect after debridement combined with internal xation of clavicle fracture, exhibiting good anti-infection ability 11 . Compared with free skin ap, this skin ap can provide higher anti-infection ability and ap blood supply to prevent the occurrence of skin ap necrosis, recurrence of infection and exposure of steel plate, etc. Moreover, vascular anastomosis under the microscope is not needed for this skin ap, and the requirements of the surgeon's personal ability and local medical conditions are relatively low 12 .
However, there are still some limitations for PLDMF in the reconstruction of soft tissue defects in neck and shoulder. The main blood supply artery of the atissimus dorsi myocutaneous ap comes from the dorsal thoracic artery (the subscapular artery originates about 3.0cm below the axillary artery), and the dorsal thoracic artery usually gives off the medial and lateral branches. Based on the anatomical characteristics of the latissimus dorsi ap, the length of the vascular pedicle of this ap is about 5.0-8.0 cm, thus there is a certain range limit for pedicled transfer 13,14 . Furthermore, perforating cutaneous vessel branches of the dorsal thoracic artery are relatively small, resulting in di culties when designing the free skin ap for transplantation and the incidence of postoperative vascular crisis is high 15,16 .
Although the PLDMF can meet the requirements for the repair distance of the soft tissue defect in the shoulder, the scar is located on the shoulder and is easy to cause friction which has a certain in uence on dressing. Additionally, there is a poor aesthetic appearance.

Conclusion
PLDMF is a practically alternative treatment for the reconstruction of soft tissue defects combined with infection in neck and shoulder, including advantages of high survival rate, satisfactory functional recovery, and clinical practicality. However, surgical indications should be taken into account due to the inferior aesthetic appearance, especially for young female.
Abbreviations PLDMF pedicled latissimus dorsi myocutaneous ap Ethics approval and consent to participate All methods in this study were carried out in accordance with the Declaration of Helsinki. This study was approved by the Ethics Committee of The First A liated Hospital of Xinjiang Medical University. Written informed consent was obtained from all patients for their data to be recorded in our study.

Consent for publication
Informed consent was obtained from all patients for their data to be published in our study.

Availability of data and materials
The datasets generated and analysed during the current study are not publicly available due to limitations of ethical approval involving the patient data and anonymity but are available from the corresponding author on reasonable request. Figure 1 a Flap design and incision. b Latissimus dorsi ap inverted to cover the soft tissue defect of the shoulder. c Appearance after the skin ap transplantation.  Appearance of the skin ap after 8 months follow-up. a standing position. b shoulder abduction position. c local appearance.