Powered Instrumentation for Dorsal Reduction
Daniel G. Becker, M.D., 1 Dean M. Toriumi, M.D., 2 Charles W. Gross, M.D., 3 and M. Eugene Tardy, Jr., M.D.

ABSTRACT We describe in 1 use of powered instrumentation for precise modification of the bony nasal dorsum. Specific modifications were made to design a drill specifically for the bony nasal dorsum. This drill has a protective sheath that covers all but the active part of the drill, protecting the skin-soft tissue envelope, and it also has suction at the resection site. In some cases an osteotome is used to reduce the hump and the drill is used to achieve additional reduction and to smooth the exposed edges under direct vision. In other cases the entire bo/n/ hnmp is reduced using the drill.

The nasal dorsum drill offers a precise alternative to the rasp. The precision of Ihe drill is highlighted in cases in which limited reduction is needed, as in cases of a single or several spicnlcs requiring reduction and smoothing after osteotonn/, or a single 4 mm raised area requiring limited reduction. The design of rasps makes it difficult to work on these focal areas without unnecessarily rasping surrounding areas, whereas the drill may be useil to reduce the entire Inimp, to smooth the edges after osteotomy, or in a more precise and limited fashion when indicated. The drill may be less traumatic to the skin-soft tissue envelope because it does not reli/ on the potentially bruising back and forth motion It/pica! of rasping. The nasal dorsum drill may decrease the incidence of bony dorsal irregularities after rhinoplasly.

key words: powered instrumentation, protective sheath, suction-irrigation, bony nasal dorsum

Division of Rhinology & Facial Plastic anil Reconstructive Surgery, Uept of Otolaryngology-l lead & Neck Surgery, University of Pennsylvania , Philadelphia Pennsylvania ; -Dopl. of OtolaryngologyHead & Neck Surgery, University of Illinois at Chicago, Chicago , Illinois ; 'Depl. of OlolaryngologyHead & Neck Surgery, University of Virginia Medical Center , Charlottesvillc , Virginia ; 4 Dept. of Ololaryngology-1 lead & Nerk Surgery, University of Illinois at Chicago, and Tardy Facial Plastic Surgery Institute, Chicago , Illinois

Reprint requests: Dr. Becker, Dept. of Otolaryngology — Head and Neck Surgery, University of Pennsylvania , 5 Ravdin/3400 Spruce Street , Philadelphia , PA 191U-I.

FACIAL PLASTIC SURGERY Volume 13, Number 4 1997

the appearance of palpable or visible irregularities that may appear as late as 1 to 5 years postoperatively. 1

When performing profile alignment, the sur­geon must recognize that the skin-soft tissue envelope is thick over the nasofrontal angle, thin over the rhinion, and thick in the supratip region. To create a straight nasal profile, a small convexity should be left in the region of the rhinion to account for the thin skin in that region. After conservative hump excision is performed, final profile refinements are made with a sharp tungsten-carbide rasp (or a powered instrument). Visual inspection and careful palpation with a hydrogen peroxide-moistened gloved finger confirm the smoothness and adequacy of resection. Forceful depression of the skin over the nasal sidewalks (simulating the skin /subcutaneous tissue contracture that eventually occurs) is an additional maneuver that may be useful in this assessment. Palpation may be impeded by edema of overlying soft tissues. To minimize edema on the dorsum, no local anesthetic is injected directly along the dorsal profile, and an atraumatic technique is emphasized.

Powered instrumentation offers a precise alternative to the rasp. These instruments may be used to reduce the entire hump, to smooth the edges after osteotomy, or in a more precise and limited fashion when indicated. In our experience, the precision of the powered drills and powered reciprocating rasps is highlighted by cases in which limited reduction is needed, as in cases with a single or several spicules requiring reduction and smoothing after hump reduction with an osteotome or a single 4 mm raised area requiring limited reduction. The design of rasps makes it difficult to work on these focal areas without unnecessarily rasping surrounding areas. The powered instruments mav be less traumatic to the skin-soft tissue

envelope because they do not rely on the potentially bruising back and forth motion typical of manual rasping. The nasal dorsum drills may decrease the incidence of bony dorsal irregularities after rhinoplasty. 4

With a knowledge of various technical aspects affecting the function of bone cutting burrs, specific modifications were made to tailor a drill specifically for the nasal dorsum. 4 There are currently at least two companies (Linvatec Corporation, Largo , FL and Xomcd, Jacksonville , FL ) with drills designed specifically for the nasal dorsum. Guarded drills were available in the early 1980s, and were designed for use in deepening the nasofrontal junction. 5 Like these early designs, current drills have a protective sheath that covers all but the active part of the drill, protecting the skin-soft tissue envelope. Current drills also have suction at the resection site (Fig. I). Some of the drills also have built-in irriga­tion.

Modifying the nasal dorsum requires a bone cutting burr with relatively increased precision and decreased aggressiveness. The fewer the number of flutes, the more aggressive a drill will be if all other factors are held constant. Burrs with two to six flutes tend to be very aggressive but are sometimes difficult to control. Burrs with eight or more flutes are less aggressive but are usually easier to control. Nasal dorsum drills are currently designed with 10 flutes.

Increased speed of rotation tends to improve both rate of resection and controllability of the cut. However, irrigation is critical to avoid thermal necrosis, and the burr may resonate or chatter at certain speeds within their range.

Selection of drill size is dependent upon ap­proach. External rhinoplasty approach allows 4.5 mm drill. Typically this drill is too large to allow direct visualization when using an endonasal approach. A smaller (typically 4.0 mm) drill is gener

ally more manageable in this setting. A powered, reciprocating rasp (United American Medical Co., McMinnville , TN ), with minimal (0.5 cm) back and forth excursion may provide another minimally traumatic alternative for modification of the bony dorsum (Fig. 2). 4

INDICATIONS

Indications for use of the powered instruments described here include the typical indications for the use of a rasp. Reduction of the bony nasal dor-sum and "smoothing" of the dorsal edges of the nasal bones comprising the "open roof" after hump reduction are amenable to powered instrumentation. Power instrumentation is also well-suited to reduction of a focal bony irregularity. The nature of the drills also allows their use for reduction of the nasofrontal angle. 5

Preoperative Considerations

Detailed preoperative anatomic analysis of the nose is an essential first step in achieving a successful outcome. Failure to recognize a particular anatomic point preoperatively will often lead to an unsatisfactory long-term result. As a general rule, the bony contribution to the profile is considerably less that that of the cartilaginous contribution. It is critical to note the general thickness of the nasal skin, as thinner skin leaves the patient at higher risk for visible or palpable profile irregularities after hump reduction. The varying thickness of the skin along the length of the nose (see above) should also be noted.

Regardless of the instrumentation used, modifi­cation of the dorsal profile is undertaken prior to lateral osteotomies.

A patient example illustrates a typical applica­tion of the powered instrumentation (Fig. 3). This female patient with medium-lo-lhin thickness skin has a twisted nose, a dorsal convexity, and a bulbous nasal lip. Her primary desires are a straight nose, improvement in the nasal profile, and refinement of the nasal tip.

Anesthesia included injection of 1% lidocaine with 1/100,000 epinephrine. By injecting along the lateral aspect of the nasal wall, the vascular supply to the dorsum, which travels from lateral to medial, is addressed. Injection along the nasal dorsum is thereby avoided. After completion of septoplasty via a hemitransfixion incision, exposure of the tip and dorsum was achieved via the external approach in this case. With exposure of the nasal dorsum, and after cartilaginous hump modification, a sharp Rubin osteotome was seated at the osseocartilaginous junction for conservative excision of bony hump. A 4.5 mm nasal drill was employed under direct visualization at 3000 rpm to achieve final profile refinements. Suction and irrigation were provided constantly as discussed above. Visual in­spection and careful palpation with a hydrogen peroxide-moistened gloved finger guided these maneuvers and confirmed the smoothness and adequacy of resection.

We have reported our experience with over 30 patients (American Academy of Facial Plastic and Reconstructive Surgery National Meeting, San Fran­cisco, September 3, 1997). The nasal dorsum drill was used in patients undergoing modification of the bony dorsum. In some patients with a small dorsal concavity the entire bony hump was reduced using the drill. In other cases an osteotome was used to reduce the hump and the drill was used to achieve additional reduction and to smooth the exposed edges under direct vision. Standardized preoperative and postoperative photography was obtained (Fig. 4).

The nasal dorsum drill was used successfully in all cases. There were no complications related to the use of the drill. There was no damage to the skin-soft tissue envelope by the drill in any case. There were no cases of drill malfunction. Postoperative ecchymosis and edema was subjectively improved compared to the prior experiences of the operating surgeons. There were no cases of dorsal irregularities with at least 6 month's follow-up.

Also, a cadaver study was undertaken in which the bony dorsum of one cadaver was rasped, while the bony dorsum of a second cadaver was reduced with the nasal dorsum drill. The nasal bones were then removed and submitted for scanning electron microscopy. Scanning electon microscopy of the cadaver specimens highlights the smoother bony surface created after use of the nasal dorsum drill (Fig. 5).

DISCUSSION

Powered instrumentation appears well-suited for precise reduction of the bony dorsal hump, an isolated bony irregularity, or to smooth the edges of the "open roof." Unlike the manual rasp, powered instrumentation allows direct visualixation of the operative site. Suction and irrigation are imperative when using these drills. The importance of careful pre-operative nasal analysis cannot be overemphasized.

The nasal dorsum drill appears to offer a precise alternative to the rasp. In our experience, the precision of the drill is highlighted by cases in which limited reduction is needed, as in cases of a single or several spicules requiring reduction and smoothing after osteotomy, or a single 4 mm raised area requiring limited reduction. The design of manual rasps makes it difficult to work on these focal areas without unnecessarily rasping surround­ing areas, whereas the drill may be used to reduce the entire hump, to smooth the edges after osteotomy, or in a more precise and limited fashion when indicated. The drill may be less traumatic to the skin-soft tissue envelope because it does not rely on the potentially bruising back and forth motion typical of rasping. The nasal dorsum drill may decrease the incidence of bony dorsal irregularities after rhinoplasty.

REFERENCES

1. Tardy ME Jr. Rhinoplasty: The Art and the Science. Philadelphia : WB Saundurs; 1997
2. Johnson CM, Toriumi DM. Open Structure Khinoplasly. Philadelphia : WB Sauriders; 1990
3. l.arrahee WF, Jr. Open rhinoplasty and the upper third of the nose. Facial Plastic Surg Clin North Am 1993; 1:23-38

Becker DG. Technical considerations in powered instrumentation. Otolaryngol Clin N America 1997;30:421-^t34 Guyuron R. Guarded burr for deepening of nasofronlal junction. I'ldst Reconstr Surg 1989;84:513-516

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