There are a number of different methods to accomplish the primary goal of liposuction. The techniques used in the face and neck, as compared with those used in the body, although very similar in mechanics must differ because of differing anatomy and physiology. When considering liposuction of the face and neck, the surgeon must be cognizant of the thinness of the facial skin, the proximity of sensory and motor nerves (mainly the marginal mandibular branch of the facial nerve), the depth of fat to be aspirated, and the natural effects of aging on facial fat deposits.
Liposuction, as it was introduced in the 1970s, makes use of a rigid cannula and a suction device.1,2 The cannula is rapidly advanced and retracted through the fatty deposits via subcutaneous tunnels. Fat cells are sharply avulsed by being drawn into the perforated cannula by the negative pressure created by the suction device. If the suction pressure is high enough results were good and continue to be so with this technique.
The addition of tumescence-the infiltration of hypotonic saline combined with local anesthetic-to the liposuction reg-imen had great applicability for body contouring. It allowed larger body area liposuction to be performed under intravenous sedation, and physiologically the infiltrated saline served to disrupt fat cell membranes and facilitate high volume fat aspiration.26-28 Tumescence effectively allows infiltration of the vasoconstrictive fluid across the entire liposuction bed. Waiting the suggested 15 minutes prior to initiation of the procedure allows the epinephrine to work and markedly decreases bleeding. Some in facial plastics use tumescence in smaller volumes not only for fat aspiration but for tissue plane dissection as well. Tumescence may be detrimental in small areas, such as the face and neck, secondary to the distortion produced by the fluid.5,29 This distortion can make assessment of symmetrical fat removal difficult. For the body, anticipated large-volume procedures benefit from tumescence to ease fat removal and dissipate heat generated, especially when ultra-sonic energy is used.29 A recognized drawback with use of the tumescent solution is the problem of third-space volume shifts.
The demand for body liposuction and the continued quest for better results with low morbidity have led to the develop-ment of another relatively new technique. The technique makes use of ultrasonic energy either internal or external to the fatty deposit, for fat cell disruption and facilitated aspiration. Although the use of ultrasonography for tissue aspiration dates to the late 1960s, only recently has it been utilized for fatty liposuction purposes. Many of the more common areas of localized body adiposity have a high fibrous content 26 and advancement of the liposuction cannula with the internal or external ultrasound device is not only less strenuous for the surgeon but reportedly more efficient for fat aspiration.27,28,30 Some studies of body liposuction with ultrasonographic assistance also report less swelling and less bruising postoperatively.31
Physiologically, the ultrasonic energy is transformed into mechanical vibrations that create a "micromechanical effect, a cavitational effect (expansion and compression cycles form microcavities in adipose tissue) which then implode, resulting in cellular destruction, i.e., liquefaction of fat, and a thermal effect on fat cells."28 Numerous studies show potential prob-lems with use of subcutaneous ultrasonic energy, such as excess heat generated by the ultrasound device at the skin incision site, 8,28,32 and the potential heat-related complications generated at more distant subdermal sites. 1,33 Use of the external ultrasonic liposuction device is discussed less frequently in today's literature. When it is discussed, it is touted as having similar benefits as internal ultrasonography in terms of surgical facilitation and recovery period but is still considered an area warranting greater study.26,27,34 The most recent literature discussing this technique is unable to offer definitive guidelines for use of the external device but rather suggests ranges of safety.34
The facial plastic surgeon should be cautious when con-sidering use of internal ultrasonography-assisted liposuction in the cervicofacial area second to the close proximity of neural structures-both sensory and motor-and the thinness of the overlying dermal and epidermal cover. An animal-based study by Howard evaluated the effects of ultrasonic energy on neural tissue. The study results showed that low amplitude ultrasonic energy applied directly to the nerve induced visible injury to the nerve.29 No functional evidence of nerve injury was noted, however, until higher amplitude settings were reached. The majority of literature that discusses ultrasound-assisted liposuction recommends following manufacturers' guidelines for power settings and suggests a range of settings considered safe. Our Medline search has failed to show any controlled studies demonstrating the safety or added benefit of ultrasound-assisted liposuction in the face or neck as compared with the standard microcannula liposuction procedure.
The final newcomer to the liposuction forefront is the liposhaver, as advocated by Gross and Becker35,36 for direct lipectomy or for use in a closed technique in the cervicofacial area. A similar tool has made great strides in the endoscopic sinus arena37 and has also been advocated by some for use in nasal dorsal rhinoplasty.38 The liposhaver is a guarded, motorized blade that is reported to remove fat via sharp excision either under direct vision or under a subdermal flap. Trauma is reportedly less than with standard techniques because of the excision-versus-avulsion principle. However, it is interesting historically to recognize that liposuctioning, as originally proposed by Schudde,1 made use of sharp curet-type instruments that excised rather then avulsed fatty deposits. This technique fell from favor following reports of tissue death and even loss of an extremity secondary to vascular damage.
The shaver differs from the traditional, the tumescent, and the ultrasonographic liposuction techniques in that it does not require high suction pressures and actively excises rather than avulses the fatty deposit.35,36 This method, although based on a similar principle as the sharp curet technique, is different in that a tunnel network is created with the liposhaver cannula much like the network seen in traditional methods. The tunnel network preserves the neurovascular network. Multi-institutional comparison trials36 have shown successful use of the device and offer it simply as an alternative to conventional liposuction, with perhaps less postoperative bruising and in experienced hands precise lipolysis. Greater care must be exercised when using this device to ensure that only subcutaneous fat is excised and aspirated and that no dermal contact is made. When used in a closed procedure, the tent and superficial projection of the cannula tip-accomplished by the surgeon's nondominant hand- allow even fat extraction and prevent vessel or nerve injury. Concerns with seromas and hematomas may be slightly increased with use of the liposhaver as compared with the traditional liposuction method.
