The Use of Ultrasonic Shears for the Harvest of Perforator Free FlapsUltrasonic Shears to Harvest Perforator Free Flaps

The use of perforator free flaps is increasing in the field of microvascular reconstruction. These free flaps have been used to reconstruct defects in the head and neck, breast, and other areas of the body, including the extremities.¹ Harvest of the flaps involves isolation and meticulous dissection of the perforator vessels along musculocutaneous paths.² High-voltage, low-current bipolar electrocautery and hemoclips are often used during flap dissections.³ We propose an alternative, ultrasonic shears, whose use can be safe and efficacious in perforator flap dissection.

Ultrasonic shears, which were originally developed by Amaral⁴ in 1994, use high-frequency energy (55 500 Hz) to cut tissues and to ligate blood vessels simultaneously. They are powered by a generator that uses an acoustic transducer to convert electrical energy into high-frequency mechanical vibrations. Their tips vibrate in a longitudinal direction at a rate of 55 500 cycles per second. The mechanism of action is therefore fundamentally different from that of electrocautery, which causes tissue desiccation, resulting in a char formation that seals the blood vessel. In contrast, ultrasonic shears use mechanical vibrations to disrupt the hydrogen bonds that are found in proteins. As a result, a protein coagulum is established and hemostasis is achieved.⁵

The clinical use of ultrasonic shears can be seen in various surgical settings, including cardiovascular, laparoscopic, and gynecologic procedures. In an animal study, Inaba et al⁶ showed that the use of ultrasonic shears resulted in shorter operative time and less histologic damage when compared with electrocautery. However, studies involving the use of ultrasonic shears in reconstructive surgery are sparse. Deo et al⁷ demonstrated that the use of ultrasonic shears resulted in shorter flap dissection time, decreased blood loss, and lower total drainage volume in patients who were undergoing pectoralis major myocutaneous regional flaps to repair head and neck defects. Based on a review of the available literature, we believe that this is the first analysis of the use of ultrasonic shears for the harvest of perforator free flaps.

Using an institutional review board–approved protocol, a retrospective chart review was performed at the Ronald Reagan UCLA Medical Center, Los Angeles, California, over an 18-month period. The perforator free flap chosen for analysis was the anterolateral thigh (ALT) flap. A computer-based review of operative notes and a manual review of postoperative clinic notes were performed for patients undergoing head and neck reconstruction with ALT free flaps. The study included only ALT flaps that had a musculocutaneous perforator that required a perforator dissection through the vastus lateralis muscle. The site of origin and the number of perforator vessels that were dissected using ultrasonic shears were recorded. Perforators from the descending or transverse branches of the lateral circumflex femoral artery (LCFA) were noted and analyzed. The ALT flap viability and wound healing complications also were recorded within the 30-day postoperative period.

All flaps selected for inclusion in this study had musculocutaneous perforators that arose from either the descending branch (type I perforators) or the transverse branch (type II perforators) of the LCFA. Surgical dissection was performed following a previously defined method.⁸ We used commercially available ultrasonic shears (Harmonic Ace; Ethicon Endo-Surgery Inc, Cincinnati, Ohio), with standard settings of 3 for minimum and 5 for maximum, to divide the overlying vastus lateralis muscle and simultaneously to ligate small side branches of the cutaneous perforator (Figure 1). The perforators were followed proximally through the vastus lateralis muscle until their site of origin from the LCFA was identified and the course of the perforators was fully exposed (Figure 2).

A review of the medical records revealed that a total of 23 patients underwent ALT reconstruction. Of these 23 patients, 5 were excluded because the ultrasonic shears were not used, and 1 was excluded because the reconstruction did not involve any musculocutaneous perforators. The remaining 17 patients who underwent harvest and transfer of ALT perforator free flaps with the use of ultrasonic shears were therefore selected and analyzed for this study.

In this sample of patients, the average flap area was 289.2 cm². A total of 41 perforators were found: 37 were musculocutaneous and 4 were septocutaneous. Of the 37 musculocutaneous perforators, 28 took a short intramuscular course from the descending branch of the LCFA (type I perforator) and 9 took a long intramuscular course from the transverse branch of the LCFA (type II perforator). Successful dissection of intact and patent perforators was achieved in 96% (27 of 28) of the descending branch perforators and in 100% (9 of 9) of the transverse branch perforators, for an overall 97% incidence of successful perforator dissection (Table and Figure 3). After we reviewed the 30-day postoperative period, we found that 100% flap viability (17 of 17) was achieved with no incidence of partial or complete flap necrosis, and no device-related wound-healing complications were observed.

Dissection of musculocutaneous perforators often requires meticulous subcentimeter soft-tissue and submillimeter vascular dissection. Historically, this type of dissection is performed with scissors, bipolar electrocautery, and hemoclips. However, newer tools are available to perform this task. One such tool is the ultrasonic shears, which are associated with less thermal injury when compared with electrocautery.⁶ The ALT flap was selected because its vascular anatomy can exemplify the complex challenges that are unique to perforator flap dissection. The anatomical variations in the ALT highlight the importance of a safe dissection. The use of ultrasonic shears in dissecting this type of flap was demonstrated in this study.

According to a review of current literature, this is the first known study that analyzes the use of ultrasonic shears in harvesting perforator free flaps. Seventeen patients, with a total of 37 musculocutaneous perforators, were examined. The ultrasonic shears were used to successfully dissect 97% of all the musculocutaneous perforators (Figure 3). A single submillimeter perforator was dissected unsuccessfully. While it arose from the descending branch of the LCFA, this small-caliber blood vessel was inadvertently lacerated during an attempt to divide the overlying vastus lateralis muscle. The other 27 musculocutaneous perforators were dissected intact from the descending branch. The perforators from the transverse branch of the LCFA are generally regarded as more difficult to dissect because of their long intramuscular route (usually 10 cm).⁸ The ultrasonic shears proved to be 100% successful in dissecting all 9 perforators from the transverse branch. During each dissection, the ultrasonic shears were placed and activated within a few millimeters of the perforators, with the insulated portion of the ultrasonic shears facing the perforator. Therefore, the instrument was effective for dividing muscle, sealing small blood vessels, and minimizing collateral damage caused by the lateral spread of thermal energy. Also, the use of the ultrasonic shears was associated with 100% flap viability and no device-related wound-healing complications within the 30-day postoperative review period.

Despite the promising results of our data, conclusions must be drawn cautiously as this study has clearly identifiable shortcomings. First, our data set of 17 patients and 37 perforators is small and serves only as an introduction in surgical technique. Second, our study does not compare the outcomes achieved using ultrasonic shears with those achieved with bipolar electrocautery or hemoclips. Deo et al⁷ have shown certain benefits of using ultrasonic shears over electrocautery in myocutaneous regional flaps (eg, decreased operative time). However, based on our data and study design, we are unable to claim that ultrasonic shears are more efficacious and/or safer than electrocautery or hemoclips for the harvest of perforator free flaps. Another disadvantage of ultrasonic shears that must be considered is the cost of this 1-time-use, disposable instrument. At our institution, the per-unit cost of a disposable ultrasonic shears hand piece is approximately $500.

Ultrasonic shears can provide an alternative method for the harvest of perforator free flaps. This study introduces the ultrasonic shears as a device for the surgeon to use in close proximity to perforator blood vessels, while causing minimal to no collateral damage. As the popularity of perforator free flaps remains high, ultrasonic shears may find increasing utility in this surgical harvest technique. Based on our positive experience, we recommend the use of ultrasonic shears for harvesting perforator free flaps.

In conclusion, the use of ultrasonic shears allows the transection of muscle and the ligation of adjacent microvessels simultaneously without causing significant injury to the perforator. While it is still in its infancy, the use of ultrasonic shears in perforator free flaps appears promising and can be applied to a variety of reconstructive surgical procedures. Further analysis with prospective studies comparing ultrasonic shears with bipolar electrocautery and hemoclips is necessary to determine which surgical tools provide the greatest advantage in harvesting perforator free flaps.

Correspondence: Vishad Nabili, MD, Division of Head and Neck Surgery, Center for Health Sciences, 10833 LeConte Ave, Room 62-132, Los Angeles, CA 90095 (vnabili@mednet.ucla.edu).

Accepted for Publication: March 20, 2009.

Author Contributions: Dr Nabili had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Blackwell, Sercarz, Abemayor, and Nabili. Acquisition of data: Ahmed and Nabili. Analysis and interpretation of data: Ahmed, Sidell, Blackwell, and Nabili. Drafting of the manuscript: Ahmed, Sidell, and Nabili. Critical revision of the manuscript for important intellectual content: Ahmed, Sidell, Blackwell, Sercarz, Abemayor, and Nabili. Statistical analysis: Ahmed, Sidell, and Nabili. Obtained funding: Nabili. Administrative, technical, and material support: Ahmed, Sidell, Blackwell, Abemayor, and Nabili. Study supervision: Sidell, Blackwell, Sercarz, Abemayor, and Nabili.

Financial Disclosure: None reported.