Background

The external rhinoplasty approach to the nose provides maximal exposure of the lower lateral cartilages, upper lateral cartilages (ULCs), middle nasal vault, and bony nasal vault. These supportive structures can be manipulated in a precise and symmetric fashion. The in-creased exposure facilitates accurate suture placement and fixation of cartilage grafts. The external rhinoplasty approach also facilitates diagnostic capability and is a tremendous aid in teaching rhinoplasty (3—10) (Appendix K).

The incisions used in this approach include a transcolumellar incision connected to bi­ lateral marginal incisions. The actual configuration of the transcolumellar incision is not as critical as the placement of the incision. The incision should be made at the level of the mid ­columella where the caudal margins of the medial crura lie close to the skin and can sup-port the incision to help prevent a depressed scar. An inverted-V incision, or sorne other broken-line incision, is used to break up the scar and lengthen it to minimize scar contrac­ture. The suroical dissection must be performed in the proper areolar tissue planes to min­imize tissue damage and scarring, maintain hemostasis, and maximize redraping of the skin/soft-tissue envelope. Dissection in proper tissue planes will help preserve vascular structures of the flap, ensure flap viability, and minimize bleeding, postoperative edema, and scarring ( 11).

NASAL DISSECTION: EXTERNAL (OPEN) RHINOPLASTY APPROACH Marking the Transcolumellar Incision

Begin the dissection by outlining the transcolumellar incision used in the external rhino­plasty approach with a marking pen. Mark an inverted-V transcolurnellar incision at the level of the midcolumella (Fig. 9). The midcolumellar incision should be marked midway between the top of the nostril and the base of the columella, where the caudal margin of the medial crura lie just beneath the skin, to provide support for the incision. The midcolumel­lar incision will be connected to bilateral marginal incisions, which are placed just caudal to the caudal margin of the lateral crura (Fig. 10). The marginal incision should not be made along the rim of the nostril (rim incision). The marginal incision may be marked with a marking pen as well.

Figure 9. A,B: Inverted-V incision on the midcolumella, at a level where the margin of the medial crura lies just beneath the skin.

Figure 10. A: Marginal incisions are placed just caudal to the caudal margin of the in­termediate and lateral crura.

Mideolumellar Incision

By using a no. I I blade with it "sawin g " motion, follow the midcolumellar markings to complete the midcolumellar incision (Fig. I I ). Proceed medial to lateral on one side of the colwnella and then the other. Take special care to keep the blade perpendicular to the skin edges, thereby preventing beveling of the skin edges. (Beveling of the skin edges may lead to a "trapdoor" deformity with eventual unacceptable scar). While incising laterally, be careful to stay superficial to avoid damage to the caudal margin of the medial crura. Use a no. 15 blade to make the columellar extension of the marginal incision on both sides of the columella, 1 to 2 mm behind the leading edge of the columella (Fig. 12). This incision is made along the caudal margin of the medial and intermediate crura. By minimizing the dis ­section over the medial crus, damage to this cartilage can be avoided.

Figure 11. A-C: Midcolumellar incision made by using a no. 11 blade with a sawing motion. Keep the blade perpendicular to the skin edges, and stay superficial to avoid damage to the caudal margin of the medial crura.

Figure 12. A: Columellar extension of marginal incision. B—D: Columellar extension of marginal incision in a patient. E, F: Marginal incision.

Marginal Incision

Beginning laterally, make a light incision through vestibular skin 1 to 2 mm caudal to the caudal margin of the lateral crura. Follow the caudal margin of the lateral crura as the inci­sion is extended medially. (The dissector has already made the marginal incision on one side, here simply make a marginal incision on the other side.)

Define the Columellar Flap

By using angled Converse scissors, or another suitable dissecting scissors, elevate the thin vestibular skin of the flap that covers the medial crura. Insert the scissors beneath the col­umellar extension of the marginal incision and dissect medially in the correct plane of dis­section, below the musculoaponeurotic layer (Fig. 13). The scissors should then pass super­ ficial to the caudal margin of the ipsilateral and then contralateral medial crus (Fig. 14). Guide the scissors through the opposing columellar extension of the marginal incision (Fig. 15). During this dissection, take special care to avoid damaging the flap or the caudal margin of the medial crura. Use the scissors to spread the tissues in the plane of dissection (Fig. 16). If not positioned properly, the dissector may cut through the caudal margin of the medial crura. To avoid this, the dissector must remain caudal to the medial crura and dissects very carefully.

Flap Elevation

Use the Converse scissors to complete the midcolumellar incision without beveling the incision or damaging the medial crura (Fig. 17). Take special care to avoid beveling this in ­cision. Use a narrow double-prong hook to retract the flap. The paired columellar arteries may be seen, and typically must be cauterized with bipolar cautery.

Figure 13. To elevate the thin vestibular skin of the flap that covers the medial crura, insert the scissors beneath the columellar extension of the marginal incision and dissect medially in the correct plane of dissection, below the musculoaponeurotic layer. If one meets resis­tance, they can alternate dissection to the contralateral side of the columella.

Figure 14. The scissors pass superficial to the caudal margin of the ipsilateral and then contralateral medial crus.

Figure 15. Guide the scissors through the opposing columellar extension of the marginal incision.

Figure 16. A, B: Spread the tissues in the plane of dissection.

Figure 17. A, B: Complete the midcolumellar inci­sion. Do not bevel the skin edges, or an unaccept­able scar (due to a trapdoor deformity) may result.

To elevate the skin/soft-tissue envelope over the nasal tip, (a) place a wide double-prong hook along the margin of the nostril rim caudal to the lateral crus, (b) place a small double – prong hook on the columellar flap, and (c) place a small double-prong hook on the vestibu ­lar skin side of the intermediate crus (Fig. 18). Then use Converse scissors to dissect the columellar flap from the caudal margin of the medial and intermediate crus, as the coun­tertraction acts to expose the areolar tissue plane. The scissors are used to expose the cau­ dal aspect of the lateral crus as well. Then the dissection advances cephalically over the sur ­ face of the lateral crus. As the dissection continues along the surface of the lateral crux, soft tissue is elevated, leaving only perichondrium on the cartilage. As dissection proceeds lat ­erally along the lateral crux, cut the vestibular skin along the caudal margin of the lateral crux, thereby completing the marginal incision. Make small, calibrated cuts under direct vi ­sion to avoid inadvertently cutting through the lateral crus. Limit dissection of the lateral crux to the areolar tissue plane deep to the muscle. A cotton-tip applicator can be used to complete the dissection of the lateral crus once the deep aerolar tissue plane has been iden ­ tified. A portion of the dissection on the opposite side was performed with the cartilage de -livery approach, nevertheless, repeat these maneuvers on the opposite side to complete el­evation of the skin/soft-tissue envelope over the nasal tip.

[An alternative approach to this dissection is to begin dissection through the marginal in ­ cisions (retrograde dissection) (12).1 In this approach, identify the proper tissue plane, and elevate the skin/soft-tissue envelope off the lateral crux. Then proceed medially with scis­ sor dissection toward the domes and intermediate crura. This maneuver is performed bilat ­erally to achieve elevation of the skin/soft-tissue envelope.

This retrograde dissection is helpful if the surgeon is having difficulty following the cau ­ dal margin of the intermediate and lateral crus. This is not unusual in cases in which there is buckling of the intermediate crus or domes. Retrograde dissection generally is not the ap ­proach of choice for secondary rhinoplasty, as the lateral crura may have been excised or previously dissected.

[Examine the lateral crura on the side of a transcartilaginous incision and cephalic trim. Evaluate the excision of cephalic cartilage. Was it stopped too short, leaving cephalic lat­eral crus at the dome region’? Did the incision go too far, was the dome inadvertently di­ vided’? Was too much cartilage taken’? Measure the amount of lateral crus remaining, there should be at least 7 mm to 9 mm.]

Figure 18. A, B: With three-point countertraction exposing the areolar tissue plane, use Converse scissors to dissect soft tissue from the caudal margin of the intermediate and lat­ eral crus. Dissection of the skin/soft-tissue envelope proceeds in the deep areolar plane be -low the muscle, leaving only perichondrium on the cartilage. C: As dissection proceeds lat­erally, follow the caudal edge of the lateral crus and cut the marginal incision. Make only a very small cut at a time, and take great care to avoid cutting the cartilage. D: As dissection continues laterally, the marginal incision is extended laterally as described above. E: When dissecting the proper tissue plane, a cotton-tip applicator can be used to sweep soft tissue off of the lateral crus. F: Completed exposure of the left lateral crus via the external ap­proach. G: Dissection has been completed of both the left and right lateral crus, and atten­tion will now be directed toward the midline.

Divide fibrous connections in the midline near the surface of the domes to release the flap and allow dissection cranially (Fig. 19). Do not dissect tissue from between the domes; otherwise a midline band of tissue may be left on the flap. Shift the dissection to the mid-line, where the anterior septal angle is identified with a spreading action of the Converse scissors or other suitable dissecting scissors. Once the blue hue of the cartilaginous middle third of the nose has been identified, create a midline tunnel over the cartilaginous middle vault. Then use a cotton-tip applicator to dissect bluntly the soft-tissue envelope cranially and laterally (Fig. 20). This maneuver will frequently expose sizable blood vessels that can be spared, as they are dissected laterally. Depending on the degree of exposure that is needed, some fibrous connections may need to be cut near their attachment to the carti­laginous nasal vault (Fig. 21). Muscle and vessels can be spared by dividing tissues close to the surface of the cartilages.

Figure 19. A—C: Shift the dissection to the midline, and divide fibrous connections in the midline near the surface of the domes to release the flap and allow dissection cranially. Do not dissect tissue from between the domes; otherwise, a midline band of tissue will be left on the flap. With a spreading action of the Converse scissors or other suitable dissecting scissors (D, E), identify the blue hue of the cartilaginous middle third of the nose, and cre­ate a midline tunnel over the cartilaginous middle vault (F).

Figure 20. A: If dissection proceeds in the proper tissue plane, a cotton-tip applicator can assist in the exposure. B: Divide the decussating fibers (apply bipolar cautery first) to con­nect the dissected spaces over the middle vault and lateral crura.

Figure 21. A, B: Exposure of the middle nasal vault.

Exposure of Cartilaginous and Bony Dorsum Exposure of the Cartilaginous Vault

The cartilaginous vault, typically corresponding to the middle third of the nose, can be exposed as described earlier. Alternatively, as with a cartilage-splitting, retrograde, or de- livery approach, the skin/soft-tissue envelope can be exposed either by using sharp scalpel dissection or by scissor dissection in the supraperichondrial plane.

Use a scalpel (no. 15 blade) or long, slightly curved dissecting scissors to elevate the soft tissues in the midline, working up toward and just beyond the rhinion, inserting and open­ing, but not cutting, with the blades under the skin.

Lay bare the perichondrium of the ULC in the midline but do not extend too far laterally at this stage. "Take special care not to follow the ULC below the caudal margin of the nasal bones. Such a maneuver may result in disarticulation of the ULCs from the nasal bones.

Elevation of Periosteum/Exposure of Bony Vault

Under direct vision by using an Aufricht or Converse retractor, use a Joseph periosteal elevator or other appropriate instrument to cut through the periosteum 2 mm cephalad and parallel to the caudal margin of the nasal bones (Fig. 22).

Alternatively, palpate the junction between the nasal bone and ULCs with the Joseph el­ evator beneath the skin/soft-tissue e n v elope by gently allowing the Joseph to "fall" off the nasal bone onto the ULCs as it is withdrawn. The Joseph elevator can then be seated 2 mm above this junction with certainty, and the periosteum incised. Elevate the periosteum off the bony nasal vault up to the nasion. Then elevate in the subperiosteal plane over the bony dorsum toward the midline and laterally (Fig. 23). Execute these maneuvers bilaterally (Fig. 24). Do not extensively undermine over the side walls of the bony nasal pyramid at

Figure 22. Subperiosteal dissection over bony nasal vault up to the nasion.

Figure 23. Cross section at level of nasal bones, illustrating dissection in subperiosteal plane. Lateral and medial motion of the elevator achieves this elevation in the subperiosteal plane.

Figure 24. After bilateral elevation, the midline decussating fibers remain undivided. These generally are severed with scissors.

this stage. Next, sever the midline internasal suture attachments; this can be accomplished with scissors or sharp elevator. Make sure that the nasal skeleton is completely freed from the overlying skin. Pass an elevator or similar instrument from side to side over the bony-cartilaginous dorsum. This completes the execution of the external rhinoplasty approach.

[The dissector now has exposure via the external rhinoplasty approach. When achieving exposure via an endonasal approach, the intercartilaginous or transcartilaginous incisions are typically connected caudally in the midline and continue over the caudal septum as a high partial-transfixion incision, as described previously (see Fig. 41) and E). Direct visu­alization of the nasal dorsum is thus achieved with the aid of an Aufricht or Con v erse re-tractor inserted through the intercartilaginous or transcartilaginous incision.

l Note: If the dissector wishes to place spreader grafts via a precise pocket endonasal ap ­ proach, it should be undertaken now. The technical steps are described in Chapter 8. Later, after hump removal (Chapter 6) and osteotomies (Chapter 7), the dissector will place spreader grafts via the external rhinoplasty approach.

PEARLS

• If the surgeon plans to place a dorsal graft or radix graft, a precise pocket can be made over the upper dorsum and/or radix. This will allow the surgeon to place the graft into a precise pocket and minimize the chance of graft migration.

• If the surgeon plans to place an alar batten graft, the lateral extent of the dissection should be minimized.

• During the external rhinoplasty approach, elevation of the skin/soft-tissue enve­lope from the underlying supportive structures of the nose results in disruption of the minor tip-support mechanism provided by the attachment of the skin/soft-tis­ sue envelope to the lower lateral cartilages. To help offset this loss of tip support, a columellar strut cartilage graft can be sutured in a pocket between the medial crura. Such a strut is used to support the medial crura to preserve tip projection and not necessarily to increase tip projection (Appendix F).

• The columellar extension of the marginal incision should be placed only 1 to 2 nun behind the face of the columella to minimize dissection of vestibular skin and to avoid damage to the caudal margin of the medial crura.

• When advancing the converse scissors across the columella to the opposite marginal incision, special care should be taken to remain caudal to the medial crura.

• Dissect in the tissue plane just above the perichondrium. Avoid violating the mus­cle layer.

• During dissection, follow the caudal margin of the lower lateral cartilages. If the caudal margin is lost sight of, move laterally to pick up the lateral crux, and dissect retrocyrade to avoid cutting across a buckled intermediate crus or deformed dome.

• Precise closure of the midcolumellar incision, with meticulous alignment of the skin edges, is critical to prevent an unsightly scar. Principles of skin-edge eversion and tension-free closure will also help prevent a visible scar. Vertical mattress-suture closure aids in skin-edge eversion.

REFERENCES

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