Nuances of Profile Management- The Radix
Rhinoplasty Surgical Planning of the Nasal Profile
Planning surgical management of the nasal profile begins by determining the ideal configuration of the nasal bridge utilizing the aforementioned aesthetic nasal principles. Height and contour are evaluated at the radix, rhinion and nasal tip. Each component of the dorsal profile (nasion, rhinion and tip) is individually classified as over-projected, under-projected, or of appropriate height. To balance the dorsal line, both augmentation and reduction of portions of the osseocartilagenous dorsum are in the realm of corrective possibilities. Reduction, augmentation, or a combined reduction-augmentation may be required to align the nasal profile in a balanced fashion.
In the majority of primary rhinoplasties, the radix is appropriate in position and projection and does not require adjustment. However, in twenty percent of cases, radix modification is necessary to best align the nasal profile.2 Reductive techniques may be required to remove the over developed nasal and frontal bones of a high radix. Conversely, augmentation of a low radix is achieved utilizing a number of available graft materials in a myriad of configurations.
Anatomically, the nasion is composed of the nasal and frontal bones. The nasal bones become markedly thicker in the cephalad direction, as does the overlying nasal skin and soft tissue envelope. The procerus muscle and an increased quantity of subcutaneous fat account for the thickness of the soft tissue in this region. While helpful for camouflaging imperfect radix grafts, the combination of thick skin and soft tissue causes difficulty in precisely assessing reduction or augmentation of the radix. It is also difficult to adequately reduce the projection of the radix because of the dense bone in this area of the nasal bridge. Removal of nasofrontal bone at the radix only translates to approximately 25% of the effective reduction at the surface level (sellion). 6 The surgeon must account for this inefficient translation when planning and executing surgical reduction.
An over-projected radix is often found in the setting of a prominent dorsal hump. Depending on the desired degree of reduction, the radix may be lowered with a rasp, osteotome, or drill bur. When a prominent dorsal hump is present, access to the radix is best achieved by first reducing the osseocartilagenous dorsum. In an open rhinoplasty approach, an Aufricht retractor will assist in exposing the radix and allow for reduction under direct visualization. While minor reductions of the caudal portion of the radix may be achieved with a rasp, substantial reductions necessitate more aggressive techniques. A wedge resection of the nasofrontal bones with an osteotome is often effective in reducing the projection of the radix and deepening the nasofrontal angle. If the radix is overdeveloped from significant frontal bone contribution, drilling down the bone with a guarded burr is required to produce effective change. This is accomplished under direct visualization through an open rhinoplasty approach. As more extensive surgical dissection is performed, appreciable improvement in reduction and angulation of the radix will take several months to reveal itself as edema of the thick skin and soft tissue subsides.
An over-projected or convex dorsum is the most frequently encountered deformity in primary rhinoplasty. Evaluation of the radix in relation to the dorsum will reveal the best method for a balanced profile plasty. A deep radix may bestow the appearance of a pseudo hump to an otherwise appropriate dorsal height. A deep radix may also accentuate an existing dorsal convexity. In these situations, dorsal reduction instead of or without the addition of radix augmentation will result in an over resected nasal bridge and the stigmata of a “surgical” nose. In order to achieve balanced correction, the radix must first be set to the ideal position and projection. Once set, further reduction of the dorsum may or may not be required to align the nasal profile.
Augmentation of the radix may be achieved with grafts assembled from autogenous or alloplastic material. Septal cartilage is frequently used because of its durability, effectiveness, and availability within the surgical field. When septal cartilage is insufficient or unavailable, the surgeon may turn to other autografts such as auricular cartilage, costal cartilage, or native soft tissue. Graft visibility remains the most significant risk of using cartilage to augment the radix. Depending on personal preference and cartilage availability, alloplastic implants are viable alternatives for augmentation of the radix. Although the risks associated with alloplastic nasal implants remain a significant concern, high success rates with minimal complications have been reported with the use of ePTFE (Gore-Tex; W.L. Gore and Associates, Inc, Flagstaff, AZ) as a radix graft.7
The necessary degree of augmentation of the radix directly influences graft selection. Small, 1-millimeter deficiencies can be corrected with soft tissue grafts inserted within precise pockets beneath the periosteum of the radix. The malleable nature of soft tissue grafts negates the risk of long term graft visibility, and makes it an ideal graft in this situation. Greater degrees of augmentation may be achieved with cartilage or bone grafts. Although cartilage is more commonly used compared to bone, the senior author has often used the resected bony hump for a radix graft. In such cases, the bony convexity consisting of bone and cartilage at the rhinion is resected in one piece using an osteotome. The resected specimen is then moved cephalically into the area of the radix and beneath the periosteum. The composite graft often sits perfectly in the depths of the nasion having the correct shape and contour for augmenting it.
When using cartilage grafts to augment the radix, grafts are designed as a single layer or stacked to the appropriate size and shape depending on cartilage thickness and the desired degree of augmentation. Edges are morselized, bruised, or beveled in order to prevent graft show, especially in patients with thin skin. The graft is then placed within a dissected pocket beneath the periosteum, and reassessed for position, effect and stability. If the graft is found to be unstable, a transcutaneous suture will secure the graft and prevent postoperative migration. The suture is removed at the first postoperative visit.
Aside from Asian and African-American noses, a low dorsum is infrequently encountered in primary rhinoplasty. However, augmentation of a low dorsum is often necessary in revision cases. Depending on the etiology of the deficiency, the radix may be malpositioned as well. Augmentation of the radix and dorsum are required in these cases. These deformities may be treated individually with separate grafts, but more commonly are corrected simultaneously with a single graft. A single graft has the advantage of providing a smooth, gapless transition between augmented regions, reducing the risk of graft visibility. Single grafts may extend the complete length of the dorsum extending distally from the radix. An extended radix graft fashioned from a large portion of septal cartilage can augment a deep radix increasing its projection and cephalic position while at the same time, augmenting the width and height of the rhinion. The edges of the graft are bruised or tapered in order to prevent graft visibility, and the graft is placed into a precise pocket beneath the nasal periosteum (Fig. 6).
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