Liposuction has evolved a great deal since surgeons originally used coarse curettage techniques to scrape away unwanted subcutaneous fat. Several sentinel modifications have occurred in recent decades to help produce better, safer surgical results. Included among the innovations are improved instrumentation, better patient selection and the incorporation of pre-aspiration wetting solutions.
It was Yves Ilouz, a French gynecologist who was largely credited with the popularity of the technique we now know as liposuction. American plastic surgeons, trained in Europe, adopted the technique and brought it into the mainstream. Three decades and millions of cases later, liposuction remains one of the most popular procedures in plastic surgery.
A Rough Start
The introduction of liposuction into the United States was met with mixed enthusiasm in the 1970s. Anecdotal reports soon surfaced of serious complications, even deaths associated with the new procedure. These tragic cases were especially significant because the whole concept of aesthetic, elective surgery was just evolving. The thought of a patient suffering serious complications from a medically unnecessary surgical procedure made these reports newsworthy. The negative media coverage cast a stigma upon the emerging procedure that has remained even to this day.
The reasons for the early catastrophic cases were complex. Among the problems were poor patient selection and varying degrees of practitioner skills. In addition, a lack of appreciation for significant losses of blood volume in the aspirate created hemodynamic instability. In an overzealous attempt to remove large volumes of fat, surgeons often created unacceptably low hematocrit levels.
A Safer Surgery
The mechanism of traditional liposuction, also termed suction assisted lipectomy (S.A.L.) is conceptually simple. A rigid, hollow cannula, connected to a suction machine, is inserted into the subcutaneous space. Rapid, coarse strokes by the surgeon create a series of tunnels, eventually becoming confluent, diminishing the fat panniculus. The underlying problem with the technique is that there is no tissue selectivity. The suction energy evacuates or destroys all elements of the subcutaneous tissue plane, including valuable structures such as blood vessels, nerves and fibrous tissue.
Critics of the procedure describe it as rough and traumatic, translating clinically into a painful, bloody process with a prolonged recovery. In addition, loss of essential connective tissue leads to rippling of the skin, the most common complaint following traditional liposuction. One study reported an 80 % incidence of skin irregularities following S.A.L.
The key to producing a safer result with liposuction needed to include the successful removal of fat tissue while at the same time sparing the other elements of the subcutaneous parenchyma. Several improvements were made towards this goal.
A leap forward occurred in the 1980s with the introduction of wetting solutions. Previously liposuction was a simple one-step “dry” procedure. Wetting solutions vary in their formula and quantity. However, the three fundamental elements to most infiltration solutions are saline, epinephrine and local anesthetic. The saline alters the tonicity of the adiposite, creating a more fragile cell, epinephrine is a potent vasoconstrictor, and the local anesthetic is used for pain relief. The solution is introduced into the subcutaneous tissue as a pre-aspiration step. The overwhelming benefit of wetting solutions is the significant reduction in blood loss associated with the lipoaspiration.
A New Idea
In the late 1980s and early 1990s several surgeons from Europe and South America began experimenting with a new concept. These surgeons began using ultrasound energy at a specific frequency to selectively destroy fat cells.
Ultrasonic energy was not new to medicine. Colleagues in other specialties have 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. In addition, ultrasonic energy has been harnessed in ophthalmology for phacoemulsification and by urologists performing lithotripsy for renal calculi. Neurosurgeons and general surgeons are familiar with the Cavitron 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 parenchymal architecture, including blood vessels, nerves and fibrous elements would be aspirated by the coarse cannula, along with the fat cells.
For the first time the concept of 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. Secondly, 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 finally, 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 component 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 a conversion of electrical energy to a mechanical wave. The wave is propagated down a titanium cannula shaft with a specific length producing 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 specific frequency of 20-27 kHz produced by the vibratory tip will affect primarily tissue with the lowest density, defined as tissue impedence. Fat has the lowest tissue impedence. Wetting the adipose tissue with tumescent infiltration can even further lower the impedance 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 yields selective destruction of fat tissue, largely sparing other types of connective tissue. This tissue selectivity is fundamental to the principles of ultrasonic lipoplasty and is evident at both a gross and microscopic level. In addition, in vivo endoscopic videos have demonstrated successful fat removal with preservation of soft tissue parenchymal architecture after application of ultrasonic energy.
Born in Europe, Raised in the U.S.
Several surgeons in Europe and South America began experimenting with ultrasonic lipoplasty in the early 1990s.
Instruments were rudimentary and ultrasonic generators were cumbersome, requiring constant calibration.
Nevertheless the early ultrasonic pioneers persisted. The International Society for Ultrasonic Surgery was formed to facilitate an active exchange of information. Michele Zocchi, an Italian plastic surgeon and physicist, is largely credited for introducing and advancing ultrasonic lipoplasty in these 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. The meeting was attended by surgeons from Europe, the Middle East, and Latin America. Only a hand full of American surgeons attended. 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 U.S. and international markets.
The symposium included clinical presentations and original scientific research. In addition, innovative endoscopic video material prepared by Hassane Tazi from Casablanca gave us a unique internal view of ultrasonic activity at a cellular level. The first I.S.U.S. meeting generated a great degree of excitement among the participants.
Meanwhile in the U.S. the major plastic surgery societies, anticipating the popularity of the emerging technology, formed a task force ostensibly to coordinate the safe introduction of ultrasound. The U.A.L. 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 U.A.L. cases.
Ultrasonic assisted lipoplasty arrived in the U.S. mainstream in early 1997. The technology was greeted with great fanfare and hype. U.A.L. was touted as a cure for everything from cellulite to obesity. It was not long before the media began to feature the procedures on mainstream broadcasts such as Primetime and 20/20. Patients began to ask specifically for ultrasonic liposuction. In response, surgeons clamored to take the few available courses.
The Pendulum Swings
The U.A.L. pendulum had 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. Many surgeons began to question the value of an investment in U.A.L.
Confounding the issue of ultrasonic lipoplasty was the introduction of an external ultrasound used as a pre-treatment for traditional suction lipectomy. The device used transcutaneous ultrasound similar to machines used in physical therapy. Though markedly different from internal U.A.L. the procedures were often confused and regarded as equivalent.
Finally, and most significantly, a number of assertions were made regarding U.A.L. that were not supported by clinical experience. These myths caused surgeons to both fear, and rethink the value of, U.A.L.
The Myths of Ultrasonic Lipoplasty
1. U.A.L. causes severe burns.
Isolated anecdotal cases of burns associated with U.A.L. surfaced in the late 1990s. They soon self-multiplied much like Mussolini’s air force in World War II*. 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 U.A.L. described by Zocchi: keep the tissue wet and keep the cannula moving. However, strict adherence to these two basic rules minimizes any serious risk of burn injury. Data published by this author (1) demonstrated no burns in a series of 351 consecutive cases. The three potential mechanisms of thermal-ischemic injury were outlined in this study.
2. U.A.L. causes seromas.
Certainly seromas can occur with ultrasonic lipoplasty just as they do with traditional liposuction. However, there is no evidence that any inherent features of U.A.L. predispose to a greater frequency or severity of seromas. To the contrary, our study (1) data reported only 3 small abdominal seromas which all resolved with conservative management. Careful review of published data regarding U.A.L. seromas suggest 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 obtaining post-operative compression to the surgical dead space, not the particular technique utilized.
3. Ultrasonic energy time should be limited to 5 minutes per area because of the risk of burns and seromas.
Based upon myths 1 and 2 some have speculated that the cause of these supposed burns and seromas is related to ultrasonic energy time. Guidelines have been created to limit ultrasonic energy time per area. Some have suggested that energy time should not exceed 5 minutes because of the potential for burns and seromas. 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.
More importantly, if one believes that the true value of U.A.L. is its less traumatic, tissue selectivity, then it is illogical to limit ultrasonic treatment to only a few minutes and complete the procedure, and traumatize the tissue, with traditional liposuction. In fact, this is the flaw of so-called “comparison” studies. In any analysis of the two techniques it is important to compare true, complete U.A.L. with traditional liposuction. To date, this author is not aware of such a published comparison. Moreover, this type of study would be limited by ethical considerations.
4. U.A.L. is an extension, but not a substitute, for traditional S.A.L.
I find this statement confusing yet I have heard it often. Even opponents of the technology admit that the tissue selectivity of U.A.L. make it especially helpful in difficult areas. Tissue higher in fibrous density such as the back, flanks or male breasts respond well to ultrasonic treatment. However, if U.A.L. is better for the difficult areas, why not use it everywhere? In fact, with few exceptions, ultrasonic lipoplasty has become our procedure of choice everywhere. U.A.L. is indeed an acceptable substitute for S.A.L.
5. It is necessary to complete the U.A.L. procedure with S.A.L.
Many authors favor the use of combined U.A.L. and S.A.L. The reasoning for this sequence is to use 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 S.A.L. diminishes the benefit of the ultrasonic tissue selectivity. Our preferred technique has evolved to even exclude the so-called “mopping up” phase of U.A.L. The procedure in most cases is performed, through completion, with simultaneous and continuous suction and ultrasonic energy.
6. U.A.L. should be avoided in certain body areas.
Some authors admonish the use of U.A.L. to certain body areas. Using U.A.L. 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 authors have reported successful results with few complications in these body areas. Our experience in these areas is also free of significant complications with very satisfactory results.
7. The U.A.L. cannula should be kept > 1cm. 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 a level of skill and experience with this area. However, proponents of U.A.L. 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 in order to avoid tissue dessication. Otherwise, subdermal stimulation can be performed safely with adherence to the two rules of U.A.L.
8. U.A.L. is a treatment for obesity.
Reports in Europe, Latin America and the U.S. 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 ultrasonic certainly make it an attractive option with this strategy. 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 (average ~2000cc, largest 7000cc) primarily used for localized body contouring.
It is advisable that surgeons choosing to perform large volume U.A.L. do so only after significant experience with smaller cases.
9. U.A.L. is a cure for cellulite.
Early optimistic reports included the hope that U.A.L. would “cure” cellulite. This has not been the case. However, it is true that U.A.L. is gentler and therefore smoother on the skin than the coarse gouging associated with traditional liposuction. The mechanism has been described as an air brush 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 S.A.L., are much less common with U.A.L.
10. U.A.L. 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 U.A.L. is more dangerous or difficult to learn is not correct. In fact, it is this author’s opinion that with careful adherence to the two basic rules described by Zocchi, U.A.L. can be learned quickly, performed safely and produce satisfactory results.
11. Ultrasonic energy produces dangerous free radicals.
It has been speculated that U.A.L. creates free radicals as well as potential sonoluminescent or sonochemical by-products. These are theoretical considerations lacking any clinical support. In fact in vivo studies have concluded that there is no evidence of free radical generation. Moreover, the lengthy safety record of ultrasound in ophthalmology and neurosurgery argue 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 held in Portugal. As with any emerging technology, U.A.L. has been the focus of controversy, both scientific and non-scientific. Politicians say that if something is repeated often enough it eventually becomes fact. Many assertions made about U.A.L. are based upon personal bias and not scientific evidence. These assertions have become myths.
The introduction of phacoemulsification over three decades ago had no less a 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 U.A.L. 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 this author’s 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 U.A.L. devices needs to be faster, less expensive and portable. Existing patent protection will soon expire and other manufacturers may enter the international U.A.L. marketplace. U.A.L. has great potential for the future. To insure its continued success, it is necessary for those of us who use U.A. L. 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.
* Italy’s dictator Benito Mussolini 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.