Unveiling the history and myths of ultrasonic lipoplastyI
In the late 1980s and early 1990s, several surgeons from Europe and South America began experimenting with a new concept: using ultrasound energy at a specific frequency to selectively destroy fat cells. Ultrasonic energy was not new to medicine. Colleagues in other specialties had utilized ultrasound in a great number of both diagnostic and therapeutic capacities. Pregnant women certainly are familiar with the diagnostic uses and safety record of ultrasound. Ultrasonic energy has also been harnessed in ophthalmology for phacoemulsification and by urologists performing lithotripsy for renal calculi. Neurosurgeons and general surgeons are familiar with an ultrasonic dissection device. Applications for ultrasonic energy continue to grow.
The use of ultrasound for body contouring was innovative. Previously, with traditional liposuction, the aspiration cannula could not distinguish between desirable tissue and fat. Consequently, the coarse cannula would aspirate not only the fat cells, but also the parenchymal architecture, including blood vessels, nerves, and fibrous elements. With ultrasound, selective tissue aspiration could be achieved. The idea was simple: Remove only the elements of the subcutaneous tissue needed to achieve the desired effect, and preserve the rest. Like picking off the grapes, but leaving the vine intact.
The application of this energy to plastic surgery was appealing for three reasons. First, ultrasound has an established history of safety. Second, the vibratory frequency of the ultrasonic energy can be made specific to the adipocyte. It is this tissue specificity that underlies the mechanism and benefit of ultrasonic lipoplasty. And third, since the energy for tissue fragmentation does not come from rapid surgical strokes, the process is markedly less traumatic to both the patient and the surgeon.
How it Works
The procedure is performed using a device made up of three parts. Electrical energy is converted into ultrasonic energy using an ultrasonic generator attached to a handpiece containing a piezoelectric crystal.
The application of ultrasonic energy is an extension of the concept of the conversion of electrical energy into a mechanical wave. The wave is propagated down a titanium cannula shaft of the specific length that produces a nodal sine-wave pattern. The wave is calibrated to intersect at the tip of the titanium cannula, producing a specific vibratory frequency of approximately 20–27 kHz. It is this precise calibration that prohibits bending of the titanium ultrasonic cannulae.
The frequency of 20–27 kHz produced by the vibratory tip will affect primarily tissue with the lowest density, as defined by tissue impedence. Fat has the lowest tissue impedence, and wetting the adipose tissue with tumescent infiltration can even further lower the impedence value. The result is an energy absorption specific to adipocytes. Ultrasonic energy absorption by adipocytes at a frequency of 20–27 kHz creates internal cellular instability, leading to cell-wall fragmentation and implosion. The phenomenon known as cavitation produces cell destruction, leading to fat emulsification.
The end result is that ultrasonic energy can accomplish selective destruction of fat tissue, largely sparing other types of connective tissue. This tissue selectivity is fundamental to the principles of ultrasonic lipoplasty, and it is evident at both a gross and microscopic level. In addition, in vivo endoscopic videos1,2 have demonstrated successful fat removal with preservation of soft-tissue parenchymal architecture after application of ultrasonic energy.
Born in Europe, Raised in the United States
Several surgeons in Europe and South America began experimenting with ultrasonic lipoplasty in the early 1990s. Patrick Maxwell, MD, in Nashville, Tenn, and others in the United States were also engaged. Instruments were rudimentary; ultrasonic generators were cumbersome and required constant calibration.
Nevertheless, the early ultrasonic pioneers persisted. The International Society for Ultrasonic Surgery (ISUS) was formed to facilitate an active exchange of information. Michele Zocchi, MD, an Italian plastic surgeon and physicist, is largely credited with introducing and advancing ultrasonic lipoplasty in those early, formative years.
Zocchi brought together a small group of physicians from around the world for the first international symposium dedicated to ultrasonic lipoplasty in Algarve, Portugal, in 1995. Surgeons from Europe, the Middle East, and Latin America, and only a handful from the United States, attended the meeting. Those of us who were present were very impressed with the potential of the exciting new technology. Also present were American manufacturers eager to produce an ultrasonic device for the US and international markets.
The symposium included clinical presentations and original scientific research. In addition, innovative endoscopic video material prepared by Hassane Tazi, MD, from Casablanca gave us a unique internal view of ultrasonic activity at a cellular level. The first ISUS meeting generated great excitement among the participants.
Meanwhile, in the United States, the major plastic surgery societies, anticipating the popularity of the emerging technology, formed a task force to coordinate the safe introduction of ultrasonic-assisted lipoplasty (UAL). The UAL Task Force created a one-day training course combining didactic lectures and a hands-on cadaver lab. The largest malpractice insurer for plastic surgeons joined in the effort. The company required its insureds to attend the seminar to obtain coverage for UAL cases.
UAL arrived in the US mainstream in early 1997, and it was touted as a cure for everything from cellulite to obesity. It was not long before the media began to feature the procedure on mainstream television news programs such as “Primetime Live” and “20/20.” Patients began to ask specifically for UAL. In response, surgeons clamored to take the few available courses that taught the procedure.
The Pendulum Swings
The UAL pendulum reached an apex in late 1997. The momentum soon began to shift, however. Fueled by a series of independent events, enthusiasm for the technology began to diminish.
No doubt the cost associated with the procedure became a significant factor. The two dominant US devices were both excellent machines, but they carried price tags in excess of $35,000. Participants in the UAL Task Force course, an unprecedented effort by the combined societies, were charged almost $2,000 for the one-day event. Many surgeons began to question the value of an investment in UAL.
Confounding the issue of ultrasonic lipoplasty was the introduction of an external ultrasound used as a pretreatment for traditional suction lipectomy. The device, championed by Barry Silberg, MD, used transcutaneous ultrasound similar to machines used in physical therapy. In addition, the Silberg device was significantly less expensive. Though this new device was markedly different from internal UAL, the procedures were often confused and regarded as equivalent.
Finally, and most significantly, a number of assertions were made regarding UAL that were not supported by clinical experience. These myths caused surgeons to both fear and rethink the value of UAL.
The Myths of Ultrasonic Lipoplasty
1) UAL causes severe burns. Isolated, anecdotal cases of burns associated with UAL surfaced in the late 1990s. They soon self-multiplied, much like Mussolini’s air force during World War II. (Italy’s dictator had a meager air force in comparison to the German Luftwaffe, yet his generals dared not tell him. Instead, the generals would fly the same planes from city to city prior to Mussolini’s review.) It is true that ultrasonic lipoplasty differs from traditional liposuction in that there is an exchange of energy. It is possible that prolonged stationary exposure can cause a buildup of thermal energy in the tissues. It is, therefore, especially important to adhere to the two basic rules of UAL described by Zocchi: Keep the tissue wet, and keep the cannula moving. Data published by this author3 demonstrated no burns in a series of 351 consecutive cases. The three potential mechanisms of thermal-ischemic injury were outlined in this study.
2) UAL causes seromas. Certainly, seromas can occur with UAL, just as they do with traditional liposuction. However, there is no evidence that any inherent features of UAL lead to a greater frequency or severity of seromas. To the contrary, our study data reported only three small abdominal seromas, which all resolved with conservative management. Careful review of published data regarding UAL seromas4-8 suggests that these occur more frequently in the abdomen. However, abdominal seromas, which occur with traditional liposuction as well as abdominoplasty, are more accurately a reflection of the difficulty of obtaining postoperative compression of the surgical dead space—not the particular technique utilized.
3) Ultrasonic energy time should be limited to 5 minutes per area. Based upon myths 1 and 2, some have speculated that the cause of these supposed burns and seromas is related to ultrasonic energy time. Analysis of published data does not support these artificial limits. Our study data revealed no correlation between complications and energy time, and no such limits were imposed. Surgeons in Europe and Latin America routinely use energy in excess of 5 minutes.8,9
More importantly, if one believes that the true value of UAL is its less-traumatic tissue selectivity, then it is illogical to limit ultrasonic treatment to only a few minutes then complete the procedure—and traumatize the tissue—with traditional liposuction. In fact, this is the flaw of so-called “comparison” studies.10,11 In any analysis of the two techniques, it is important to compare true, complete UAL with traditional liposuction. To date, I am not aware of such a published comparison.
4) UAL is an extension of, but not a substitute for, traditional suction-assisted lipoplasty (SAL). I find this statement confusing, yet I have heard it often. Even opponents of the technology admit that the tissue selectivity of UAL makes it especially helpful in difficult areas. Tissue higher in fibrous density, such as the back, flanks, or male breast, responds well to ultrasonic treatment. If UAL is better for the difficult areas, why not use it everywhere? In fact, with few exceptions, UAL has become our procedure of choice everywhere. UAL is indeed an acceptable substitute for SAL
5) It is necessary to complete the UAL procedure with SAL. Many authors7,9,10,12 favor combining UAL and SAL, using the ultrasound to “soften” the tissue, followed by the speedier traditional liposuction to complete the procedure. The flaw in this approach is that any use of traditional SAL diminishes the benefit of the ultrasonic tissue selectivity. Our preferred technique has evolved to exclude even the so-called “mopping up” phase of UAL. The procedure in most cases is performed, through completion, with simultaneous and continuous suction and ultrasonic energy.
6) UAL should be avoided in certain body areas. Using UAL in areas of thinner skin, such as the arms, face, neck, inner thighs, knees, and even saddle bags, has been described as risky. The risks ascribed are primarily associated with burns or devascularization injury. However, clinical data does not support this assertion. In fact, several authors13 have reported successful results with few complications in these body areas. Our experience in these areas has been free of significant complications.
7) The UAL cannula should be kept less than 1 cm deep to the dermis. The concern again here is the risk of thermal or ischemic injury to the skin. It is appropriate that surgeons treating the underside of the dermis have skill and experience with this area. However, proponents of UAL feel that the greatest opportunity for skin contraction is via stimulation in this plane. It is advisable that suction not be applied simultaneously during this step to avoid tissue dessication. Otherwise, subdermal stimulation can be performed safely, as long as you adhere to the two rules of UAL.
8) UAL is a treatment for obesity. Reports in Europe, Latin America, and the United States of large-volume liposuction have led some to suggest that liposuction may be an effective adjunct in the treatment of obesity. The tissue selectivity and markedly diminished blood loss associated with UAL certainly make it an attractive option. However, many authors have very effectively outlined the potential problems, including significant hemodynamic issues, associated with large-volume lipoplasty. Moreover, obesity is regarded as a complex condition, requiring behavior modification in addition to loss of adipose tissue. Our experience is with moderate-volume cases (averaging about 2,000 cc, with the largest being 7,000 cc), primarily for localized body contouring. I advise that surgeons choosing to perform large-volume UAL do so only after significant experience with smaller cases.
9) UAL is a cure for cellulite. Early, optimistic reports included the hope that UAL would “cure” cellulite. This has not been the case. However, it is true that UAL is gentler and therefore smoother on the skin than the coarse gouging associated with traditional liposuction. The mechanism has been described as an airbrush effect, creating a smoother plane in the subcutaneous tissue. This, coupled with subdermal stimulation, produces a more even skin retraction. Skin irregularities and waves, the most common complaint following SAL, are much less common with UAL
10) UAL is hard to learn. Certainly, any new technology will require a learning curve, both for the specialty as well as for the individual practitioner. We all approach a new procedure from a different level of skill and experience. Complications can occur with any technology, including traditional liposuction. Disastrous complications have been reported with lasers. The assertion, however, that UAL is more dangerous or difficult to learn is not correct. In fact, it is my opinion that with careful adherence to the two basic rules described by Zocchi, UAL can be learned quickly, performed safely, and will produce satisfactory results.
11) Ultrasonic energy produces dangerous free radicals. It has been speculated that UAL creates free radicals as well as potential sonoluminescent or sonochemical by-products. These are theoretical considerations that lack any clinical support. In fact, in vivo studies14,15 have concluded that there is no evidence of free-radical generation. Moreover, the lengthy safety record of ultrasound in other specialties, including ophthalmology and neurosurgery, argues against such a risk.
Where Do We Go From Here?
We have seen the ultrasonic lipoplasty pendulum swing from one extreme to the other in the decade since the first international congress was held in Portugal. As with any emerging technology, UAL has been the focus of controversy, both scientific and nonscientific.
The introduction of phacoemulsification by Kelman more than 3 decades ago had a no-less-tumultuous beginning, yet the ultrasonic procedure is now largely regarded as the standard of care in cataract ophthalmology.
The vacillating interest among surgeons has prompted manufacturers to reconsider their level of commitment to UAL. Recent modifications have included changes in cannula design and pulsed energy mode generators. The theory behind pulsed energy devices is to limit ultrasonic energy delivery to the tissues to avoid burns. In my opinion, this is a solution in search of a problem, since burns can be largely avoided by simply adhering to the two basic rules proposed by Zocchi. More importantly, pulsed energy slows the procedure down, contributing to longer surgical times.
The next generation of UAL devices needs to be faster, less expensive, and portable. Existing patent protection will soon expire, and other manufacturers may enter the international UAL marketplace. UAL has great potential for the future. To ensure its continued success, it is necessary for those of us who use UAL to work to dispel the myths and to continue to fine-tune this safe and sophisticated technology. The final result will be improved patient and physician satisfaction. n
Jorge A. Perez, MD, FACS, is in private practice in Fort Lauderdale, Fla. He has lectured internationally on UAL and was program director for the fifth ISUS Congress in 2001. He can be reached at firstname.lastname@example.org.
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