Technique for Dorsal Augmentation Using Alloplastic Material

Man-Koon Suh

Nguyen Phan Tu Dung

DEFINITION

A low nasal dorsum is one of the main characteristics of Asian noses. Dorsal augmentation is one of the most frequently performed procedures in Asian rhinoplasty.
There is a distinctive difference in preferences of materials used for dorsal augmentation between surgeons from Asia and other countries.
- Autogenous tissues preferred by Western surgeons provide better safety but have several disadvantages:
  - Less satisfaction aesthetically
  - Scars on the donor site
  - Decreased height or irregularity of the nasal dorsum due to tissue resorption
  - More complex surgical procedure compared with implants
- Thus, use of an implant is still preferred for dorsal augmentation in Asia.
Owing to the thick and fibrotic soft tissue envelope of Asian noses, as opposed to that of Westerners’ noses, implant visibility or an operated looking appearance after dorsal augmentation with implant is considerably less likely. The appropriate surgical technique complemented by a highquality implant surely minimizes the frequency of adverse effects.¹^,²^,³

ANATOMY

The structure of an Asian nose is shown in FIG 1.
Use of an implant is limited to dorsal augmentation. Tip projection should be carried out by various tip-plasty techniques including suture techniques and cartilage grafting. It is safe to use an implant only from the radix to the supratip area (FIG 2).

FIG 1 • A-D. Asian nose with a low and short nasal dorsum. Nasal bone is flat and low, and alar cartilage is small and weak as well. (D. Copyright Man Koon Suh, MD.)
Application of an implant extending to the tip area should be avoided, since it may cause thinning and redness of the tip skin or a rupture of the tip skin with implant exposure.

PATIENT HISTORY AND PHYSICAL FINDINGS

The following must be checked during the preoperative evaluation:
- Presence of facial asymmetry
- Presence of nasal axis deviation
- Presence and underlying causes of tip and nostril asymmetry
- Dorsal skin characteristics, including the texture, color, and any skin problems such as visible veins or telangiectasias
The surgeon must decide the following during the preoperative consultation:
- How high the nasal dorsum should be raised
- Whether the profile should be straight or curved
- The type of prosthesis to be used for dorsal augmentation
- The type of cartilage to be used for tip projection

SURGICAL MANAGEMENT

Dorsal augmentation material for Asians is chosen from either autogenous tissues or implants.

In cases in which the dorsal skin is too thin, autogenous tissues are recommended.

Dermofat graft or diced cartilage wrapped with the temporal fascia is preferred.

FIG 2 • Four types of dorsal and tip augmentation strategies in Asian noses. A. L-shaped implant only for dorsal and tip augmentation. B. L-shaped implant combined with cartilage graft on the tip of the implant. C. Long I-shaped implant combined with cartilage graft on the tip of the implant. D. Short I-shaped implant with cartilage graft on the alar cartilage. This is the most recommended technique for the Asian rhinoplasty. (Copyright Man Koon Suh, MD.)

A rib cartilage block used for dorsal augmentation for a patient with thin skin may result in a visible contour of the rib cartilage graft, increasing the possibility for revision surgery.

The implant can be relatively safe and bring aesthetically beautiful results for Asians when the skin is not thin.

Preoperative Planning

Implant Selection

Each material has advantages and disadvantages. Silicone and e-PTFE (expanded polytetrafluoroethylene) are used most commonly for dorsal augmentation, but other products are available, such as Medpor.
- Characteristics of silicone implants
  - There is no change in the implant height as time progresses.
  - Capsular formation.
  - The frequency of calcification on the surface of the implant is higher than that of an e-PTFE implant over a long period.
- Characteristics of e-PTFE implants
  - Micropores are present within implant, allowing tissue ingrowth. As a result, there is less implant mobility and no capsular formation.
  - Calcification occurs less in e-PTFE implants than in silicone implants.
  - Delayed spontaneous hematoma also occurs less in e-PTFE implants.
  - The height of an e-PTFE implant decreases to about 5% to 20%.⁴ Accordingly, the height predictability decreases, and tissue ingrowth makes it difficult to remove an e-PTFE implant as opposed to a silicone implant.
The answer to which type of implant is better between silicone and e-PTFE implant depends largely on the experience and preference of the surgeon. Silicone implants are generally used because there is no morphologic change over time and height predictability is excellent. Nevertheless, an e-PTFE implant may be considered for the following cases:
- A contracted nose due to capsular contracture
- Wide dorsum due to hypertrophied capsule
- Weak periosteum (cases with fragile periosteum are prone to implant mobility; e-PTFE implants have higher adherence to the nasal bones or adjacent tissues, so that implants are less mobile)
- Calcification on the surface of a silicone implant
- Foreign body reaction to silicone
- Late spontaneous hematoma inside the capsule of a silicone implant
Thin dorsal skin is not an indication for an e-PTFE implant.
- An e-PTFE implant inserted into a patient’s nose with thin dorsal skin may force the thin skin to adhere closely to the implant without capsular formation. Thus, the implant edges may be more conspicuous.
There are I-shaped (boat shape) and L-shaped silicone implants (FIG 3).
- An I shape is mainly used for dorsal augmentation, whereas an L shape is used to simultaneously raise both the dorsum and the tip.
- An L shape is not recommended because it has a risk of the nasal tip becoming too hard, tip skin thinning, and implant exposure through the nasal tip skin.

Implant Design

The patient is asked to look straight ahead, and the starting and end points of an implant are marked on the nose (FIG 4A,B).

The starting point of an implant would coincide with the double eyelid line for Westerners. However, it looks natural to have the implant starting point coincide with the eyelash line for Asians.

FIG 3 • I- and L-shaped silicone implants.

FIG 4 • A. Start and end point of the implant. B. Markings. C. The implant tip should be shortened and adjusted to fit to its ending point, which is 3 to 5 mm above the tip defining point. The dorsal line should be slightly curved and have a higher nasal tip and supratip break in women (D) but be straight in men (E). (A,D,E. Copyright Man Koon Suh, MD.)

The starting point of an implant would be somewhat higher for patients with a protruding forehead. The more protruding the forehead, the higher the position of the implant starting point. The flatter the forehead of a patient, the lower the implant starting point.

The distal end of an implant should not extend to the nasal tip but to the area just above the nasal tip. Hence, the length of an implant would be approximately 35 to 45 mm.
- No part of an implant should enter into the nasal tip under any circumstance, and the nasal tip must be projected with cartilage graft (FIG 4C).
Raising the radix area high like that of the Westerner creates a fierce-looking face for Asians. It is pertinent for Asians to have the line extending from the forehead to the radix to be natural.
The nasal tip of a female should be slightly higher than the dorsal line so as to form the natural supratip break. Accordingly, the nasal tip should also be projected by a cartilage graft. The side view line from dorsum to the nasal tip should be a straight line in males (FIG 4D,E).

Approach

Dorsal augmentation can be done through an intranasal or an open approach.
An open approach is needed in cases requiring tip plasty, whereas the intranasal approach is adequate for dorsal augmentation using a simple implant. In these cases, an inframarginal incision is recommended.

TECHNIQUES

▪ Implant Carving

The operator must be equipped with implants of various shapes and heights provided by the manufacturer (TECH FIG 1A).
Until recently, an e-PTFE block was carved into nasal implant shape (TECH FIG 1B). Now, however, ready-made products that are precarved in various shapes facilitate ease of carving (TECH FIG 1C). The carving process for an e-PTFE prosthesis is similar to that for a silicone implant.

Carving Process

The operator selects the most appropriate implant in consideration of nasal profile and the desired nasal shape of a patient.

The proximal beginning part of the implant is placed on the starting point marked on the nose, and then distal ending point of the implant is marked (TECH FIG 2A,B).