Strategies of Total Auricular Reconstruction for Patients With Poor Skin Coverage at the Mastoid Area

Background

Ear reconstruction is the best method for the treatment of congenital microtia and acquired auricle defects. It is also one of the most complex procedures in plastic surgery. There are 2 main procedures for ear reconstruction. The first is to sculpt a vivid and exquisite ear scaffold that is similar to the normal ear. The second is to choose a suitable flap to cover the ear scaffold, such as the mastoid fascia flap. There are many methods for ear reconstruction, including Brent’s method, ¹ Nagata’s technique, ² and the expanded postauricular flap method. ³ Regardless of the kind of method we choose, sufficient and qualified mastoid tissue is needed.

Ear defects can be caused by trauma, burns, and other factors. If the fascia and skin coverage is poor in the mastoid area, it will be difficult to cover the ear framework during ear reconstruction. ⁴ Some scholars use expanded mastoid fascia flaps that contain scars, ⁵ but the elasticity of flaps with scars is too poor to be expanded, so it is difficult to obtain a good effect. Therefore, some surgeons choose a temporoparietal fascia flap to cover the ear scaffold. ⁶ There is no consensus on the treatment of such patients with ear deformity and poor skin coverage at the mastoid area, so it is difficult to obtain a good outcome. In this study, we discuss auricle reconstruction for patients without satisfactory mastoid tissues.

Methods

Clinical Data

From April 2020 to July 2021, 16 patients with acquired ear deformities were enrolled in this study, including 12 males and 4 females. All of them had massive damage and poor skin coverage at the mastoid area. Twelve deformities were caused by burns, 3 by car accidents, and 1 by an ear tumor. The average age of the patients was 34 years. In 10 patients, we covered the ear framework with a temporoparietal fascia flap. Six patients underwent ear reconstruction with an upper arm flap (Table 1). In addition, we used autologous costal cartilage as an ear scaffold. The mean follow-up time was 12 months.

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Table 1.

Demographic Features of the Patients.

Variable	Value
No.	16
Age, yr
Average	34.8
Mean	34.5
Sex
Male	12 (75%)
Female	4 (25%)
Side of the ear deformity
Left	7 (43.8%)
Right	7 (43.8%)
Bilateral	2 (12.5%)
Cause of injury
Flame burn	12 (75%)
Trauma	3 (18.7%)
Tumor	1 (6.3%)
Surgical strategy of auricle reconstruction
Temporal-parietal fascia flap	10 (62.5%)
Upper arm flap	6 (37.5%)
Patient satisfaction
Excellent	9 (56.3%)
Good	4 (25%)
Fair	3 (18.7%)
Poor	0 (0)
complications
No	13 (81.3%)
Yes	3 (18.7%)

Patients with an acquired auricle defect instead of congenital microtia, massive damage of the mastoid area, a deep second-degree or third-degree burn if he or she experienced a burn and who underwent total auricle reconstruction were included in the study. All patients provided written consent. This research was reviewed and approved by the Ethics Committee of the Plastic Surgery Hospital, Chinese Academy of Medical Sciences. The principles of the 1975 Declaration of Helsinki were followed.

Surgical Procedures

1. Preoperative evaluation

It is necessary to evaluate the quality of the patient’s superficial temporal artery before surgery. We used Doppler ultrasound (BC-520P+, Bestman, China) to detect the length of the superficial temporal artery (Figure 1). The patients were divided into 2 groups based on the length of the superficial temporal artery. If the length was more than 10 cm, the blood supply of the temporal-parietal fascia flap was rich, and we could use the flap for auricular reconstruction. If the length of the superficial temporal artery was less than 10 cm, we chose the upper arm flap.

2. Total auricle reconstruction with the temporal-parietal fascia flap

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Figure 1.

Outline of the superficial temporal artery (a).

This method could complete total auricle reconstruction through a single-stage operation. We depicted the outline of the superficial temporal artery and made an “S”- or “C”-shaped incision. A 10 cm×10 cm fascial flap was separated and removed from the scalp and periosteum along with the superficial temporal artery so as to cover the whole ear framework. At the same time, the costal cartilage scaffold was sculptured. The 7th and part of the 6th costal cartilage (approximately 3–5 cm) were usually carved and spliced into a three-dimensional ear scaffold. The helix was usually formed by the outer edge of the seventh rib cartilage to avoid breaking the cartilage. The cartilage scaffold should have a fine morphology, such as a helix, crus, triangular fossa, and concha, to achieve a more realistic appearance. Cartilage strips were used to increase the thickness behind the framework to form the cranioauricular sulcus. Then, the scar and tissue of the residual ear were completely wiped off. The position of the reconstructed ear was according to the normal ear, and the ear framework was fixed to the periosteum. The framework was covered by the temporal-parietal fascia, and the fascia wound was covered by a split-thickness skin graft. The split-thickness skin was taken from the thigh, abdomen, or rib area. Finally, we placed a drainage tube that had negative pressure in the subcutaneous area and then bandaged the reconstructed ear (Figure 2).

3. Total auricle reconstruction with the upper arm flap

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Figure 2.

The temporal parietal fascia flap (b). Ear framework carved out of the 6th and 7th costal cartilage (c, d). The temporal parietal fascia flap is used to cover the ear scaffold (e). The split-thickness skin covers the ear framework and the temporal parietal fascia flap (f).

There are 5 stages in this method. In the first stage, we placed a 150 mL kidney-shaped silicon expander into the subcutaneous layer at the outside of the upper arm. Ten days later, saline injections were administered to the patients 2–3 times a week. Approximately 4–5 weeks later, approximately 450–500 mL of saline was injected into the expander. We removed the expander and carried out skin tube formation for skin flap delay. Three weeks later, in the stage III operation, the proximal end of the tube was transferred to the auricle (Figure 3). Later, the blood circulation of the flap was trained until the blood supply was stable after being clamped for more than 1 hour. The 4th-stage operation was to perform pedicle amputation four weeks later, and we implanted an 80 mL kidney-shaped expander in the mastoid area. We started injecting saline into the expander on the 7th day after surgery, and the expanding period lasted for 6–10 weeks to reach a volume of 130 mL–160 mL. This condition was maintained for another 6–8 weeks to avoid potential retraction of the expanded flap. In the 5th stage operation, the ear framework was carved and put into the mastoid area where the expander existed. The ear scaffold was carved as mentioned above. The method for constructing an ear framework was the same as auricle reconstruction with the temporal-parietal fascia flap.OPEN IN VIEWER

Figure 3.

A 150 ml expander in the subcutaneous layer at the upper arm (g, h). The expander was removed from the upper arm, and the skin tube in the left upper arm was formed as a delayed tube and transformed to ear (i).

Results

All patients were followed up, and the median follow-up period was 7.5 months (range 6-18 months). The shape, color, texture, relative position, and structure of the reconstructed ear were satisfactory. One patient had cartilage exposure at the earlobe after the operation, which was repaired by covering the exposed cartilage with posterior auricular fascia. Two patients had poor earlobe morphology, which was corrected by earlobe repair. No other complications were found in this study. Nine patients (56.3%) considered the outcomes to be excellent, 4 patients (25%) considered the outcomes to be good, and 3 patients (18.7%) considered the outcomes fair.

Typical Cases

Discussion

Adequate mastoid skin is crucial for successful total auricular reconstruction. In previous studies, researchers have reported that mastoid skin is needed regardless of the type of total auricle reconstruction.^7-9 However, some acquired auricle defects can lead to massive skin damage and poor skin coverage in the mastoid region. Such issues increase the difficulty of total ear reconstruction. ¹⁰ In conventional plastic surgery, skin insufficiency is usually resolved in 2 ways: skin grafting ¹¹ and skin expansion. ¹² The most important objective of skin transplantation is maintaining blood supply in the recipient area. ¹³ Therefore, according to the length of the superficial temporal artery, we classified the patients into 2 categories. A superficial temporal artery that is longer than 10 cm, and a temporoparietal fascial flap that can completely cover the ear scaffold. Therefore, we chose the temporal-parietal fascia flap to perform ear reconstruction. It is a single-stage reconstruction that is less time consuming and less complex. For patients with a superficial temporal artery that is less than 10 cm or a temporoparietal fascial flap is not enough to cover the ear framework, an expanded upper arm flap is chosen to cover the ear scaffold. It requires a five-stage operation, which is more time consuming and difficult than total auricular reconstruction with a temporal-parietal fascia flap.

The temporoparietal fascia flap is thin, and the blood supply is rich.^14,15 It is the primary choice for patients with extensive mastoid region lesions. This method is relatively simple, less time consuming, and more acceptable for patients. However, this method depends on the blood supply of the temporoparietal fascia. ¹⁶ Therefore, it is essential to evaluate the length of the superficial temporal artery. ¹⁷ We can use Doppler ultrasound to measure its length and judge the blood supply during surgery. ¹⁸ We suggest that if the length of the superficial temporal artery is more than 10 cm and the blood supply is good, a temporal-parietal fascia flap should be used in total auricular reconstruction. To fully cover the auricle scaffold, the temporal fascia needs to reach a range of 10 cm×10 cm.

If the temporoparietal fascia is also damaged or the length of the superficial temporal artery is less than 10 cm, the temporal-parietal fascia flap cannot fully cover the auricle scaffold. An upper arm flap should be chosen for ear reconstruction. The upper arm flap also has a rich blood supply and is well anastomosed, concealed, soft, smooth, hairless, and has good elasticity. It has been widely applied for facial restoration. Therefore, it is also an ideal donor site for ear reconstruction. ¹⁹ We expanded it on the upper medial arm and transferred the flap from the medial arm to the mastoid region via a skin tube. At the same time, we suggest that the upper arm flap should be expanded to a suitable thickness. Compared with the temporoparietal fascial flap, the expanded upper arm flap is thinner and has better elasticity, so the shape of the ear scaffold can be better revealed. In addition, the donor site of the upper arm is hidden and has few scars. However, the disadvantage of this method is that the surgical procedure is time consuming and more complex than ear reconstruction using the temporal-parietal fascia flap. ²⁰

For patients who need to improve their hearing, we implanted bone conduction devices for them. This procedure should be performed after the ear reconstruction. And it provided a good solution for patients with hearing loss. This study also requires carving of the rib cartilage. Most of the patients with traumatic auricle defects were adults. The costal cartilage is more difficult to carve in adults because it is harder and less elastic. ²¹ If we use the eighth rib for carving the ear scaffold, it is prone to break or be too sharp at the edge of the scaffold, and the shape of the auricle will be poor. ²² Therefore, we chose the seventh rib and used its outer edge as the helix. This method could make full use of the natural curvature of the seventh rib and prevent the ear bracket from breaking. At the same time, we chose the widest part of the sixth rib cartilage together with the seventh rib to make the triangular fossa, which was the base of the auricle. The remaining rib cartilage was carved into a “C” shape and spliced under the base of the ear to form the cranioauricular angle. This method can obtain a stable scaffold and a better effect of ear reconstruction. In recent years, with the development of the porous polyethylene, the ear reconstruction can be performed with the Medpor framework. The medpor has tough texture, good memory, strong plasticity, and we can obtain good postoperative result. However, as ear scaffold, the medpor material has poor histocompatibility and sometimes cause the stent exposure or infection. So it has not been used widely.

Conclusion

Ear reconstruction is very challenging if the mastoid region is damaged or the mastoid area has poor tissue coverage. We evaluated the temporoparietal fascial blood supply by measuring the length of the superficial temporal artery of these patients before surgery. We used the temporoparietal fascial flap to cover the ear scaffold if the length of the superficial temporal artery was longer than 10 cm and the blood supply of the temporoparietal region was good. If not, we chose the upper arm flap. The latter needs a five-stage operation, which is more time consuming and more difficult than the former. Moreover, the expanded upper arm flap is thinner and has better elasticity than the temporoparietal fascia, so the shape of the reconstructed ear is better. In summary, we need adequate preoperative evaluation, an appropriate amount of time, and suitable surgical strategies for these patients without satisfactory mastoid tissue to obtain a good result.