Localized and generalized accumulations of lower extremity fat have tested the skills of plastic surgeons for decades. Patients with localized fat accumulations often desire removal for aesthetic reasons, whereas patients with large, especially circumferential, accumulations desire removal for functional as well as aesthetic reasons. Kelly was one of the first to recognize the possibility of direct excision of excess skin and fat of the abdomen.  This led to direct excision of localized fat on the lower extremities.
Lewis first described the circumferential excision of thigh skin and fat with a vertical closure.  Farina performed direct lateral excision that, while improving the contour of the lateral thigh, produced huge, highly visible scars.  Pitanguy was the first to describe a thigh lift incision that was hidden within the bathing suit line.  This resection also was the first to address inner and outer thigh skin and fat excess and to correct buttock ptosis.
Over the years, thigh plasty has evolved from variations on this theme. Major variations dealt with the location of the lateral scar. Baroudi kept his lateral incisions low.  Regnault et al brought the incision higher, onto the buttock. Finally, Grazer and Klingbeil raised the incisions to the level of the midbuttock to conceal the scar beneath normal clothing. 
Flankoplasty rarely is performed alone. It is most often combined with abdominoplasty and thigh plasty procedures (see the image below). Somalo first described the circumferential dermolipectomy.  Gonzalez-Ulloa first described the belt lipectomy in 1960, adding a vertical wedge resection.  Whereas belt lipectomy is usually indicated for obesity or excess skin from massive weight loss, partial belt lipectomies can produce dramatic results.
McCraw first described multiple procedures on a patient with massive weight loss, combining abdominoplasty, brachioplasty, mastopexy, and thigh lift.  Zook was able to standardize the procedure by describing the following individual procedures and their sequence: patient marking (in the standing position), long S-shaped incisions, and preservation of veins and lymphatic vessels.  As Regnault indicates, the problem is more a resection of redundant skin and subcutaneous fat rather than a resection to cure obesity.
Today, buttock and thigh lifting continue to be relatively rarely performed procedures, for a number of reasons.
Excisional thigh and buttock surgery is technically difficult, can result in significant blood loss, and produces significant scarring. Postoperative morbidity is significant. Suction-assisted lipectomy (SAL) has gained great acceptance because of the relative ease with which it may be performed. Some authors are extending the boundaries in its use for treating obesity.  Hunstad notes that “excision contouring in the obese patient is appropriate in virtually all areas previously discussed for nonexcisional (SAL) patients.” 
The future may rest in developing combinations of the 2 techniques. This is not without risk. In certain areas, performing aggressive superficial liposuction and combining it with wide undermining is not safe. However, with experience and small cannulas (< 3 mm), dramatic results may be obtained.
The future of flankoplasty depends on the surgeon’s ability to restore normal body contour with the least possible scarring. Certainly, SAL has provided a powerful tool to remove fat. SAL does not treat skin laxity and can worsen truncal deformity. The main goal should be to improve the quality of scars. This can be accomplished by relieving the tension on them. Addressing the superficial fascial system (SFS), as described by Lockwood, appears to be the best way to do this.
The following are indications for performing thigh and buttock plasty:
Localized excess of fat and skin
Generalized excess of fat and skin
Skin redundancy with or without excess subcutaneous fat
Many physicians prefer SAL for localized fat. SAL alone is usually not adequate in the presence of excess and/or redundant skin. However, for patients with fair-to-moderate skin tone, a surprising amount of skin contraction can be performed by using superficial liposuction. Patients with poor skin tone are best served by excision.
Flankoplasty (see the image below), combined with other procedures, is indicated for patients who are moderately obese with loose skin or who have lost massive amounts of weight. In patients who have undergone bariatric surgery, weight should remain stable for at least 18 months. Patients with massive weight loss frequently have large amounts of excess skin, leading to chronic hygiene problems, especially suppurative intertrigo. Excisional surgery often is the only way to correct these problems.
This surgical procedure is not for an unmotivated patient, because of the extensive nature of the recovery and the need for frequent follow-up. Large amounts of skin and subcutaneous fat are excised, leaving long, occasionally wide, and permanent scars. The physician must understand the patient’s motivation and aesthetic goals and assess the patient’s future commitment to avoiding weight gain. The patient must have realistic ideas of what can be accomplished, must be cognizant of the location of scars, and must be aware of the amount of postoperative care required.
Patients who seek thigh and buttock plasty most often report excess skin and fat as the reason that they desire the procedure. They may also notice a cottage cheese–like appearance over the lateral thigh region and ptosis of the lower buttock. Some comment that they can see the lower part of their buttocks between their thighs when looking in the mirror. Hoffman and Simon describe the problem as the following  :
Heavy thighs and/or general obesity
Medical skin and fat excess with redundancy
Buttock ptosis with redundancy
Regnault and Daniel classify lower extremity deformities by dividing them into regional and general.  Regional deformities are those of the medial thigh, buttock, and trochanter. They treat these areas with a “single crescent excision” or a “semicircular approach.” A vertical height of 20 cm is excised in some cases. Generalized deformities are treated with a circumferential resection with or without a vertical component.
Some types of cellulite can be improved by excisional or liposuction surgery. It has been demonstrated that one type of cellulite is the result of extrusion of subcutaneous fat into the reticular dermis. The pattern of connective tissue differs between males and females, with women having a diffuse pattern of a regular and discontinuous connective tissue immediately below the dermis and men having a smooth and continuous pattern.
Cellulite may be removed by direct excision of the involved area. Its tethering effect can be improved using a subcision technique. Other irregularities may be improved by adipose autografts.
Contraindications include unrealistic patient expectations, inability to deal with major unpredictable scarring, peripheral arterial or venous disease, and lymphatic disease. Note any previous surgery that may affect venous or lymphatic drainage of the lower extremity, such as pelvic exenteration and gynecologic procedures leading to inguinal lymph node dissections. Patients who have undergone varicose vein stripping or saphenous vein harvest probably are not good candidates. The author does not perform this procedure on people who smoke.
Major resections are contraindicated in patients who are massively obese, especially those with comorbid factors (eg, cardiovascular disease, diabetes mellitus, cancer, and decreased pulmonary function). They are also contraindicated in patients with massive weight loss and multiple metabolic derangements from previous surgery.
Pathophysiology and Etiology
The etiology of the problem may be obesity, weight loss, aging, congenital defect, or a posttraumatic defect.
Body fat distribution is determined by gender, age, degree of physical activity, nutritional habits, and, in some circumstances, drugs. In men, body fat percentage may increase from 20% in young people to 25% in older individuals. For women, the percentages are 30% and 35% for young and old persons, respectively. At all ages after puberty, women have a higher percentage of body fat than men do.
Distribution of fat also differs between genders. Whereas women tend to accumulate fat in the hips and thighs, men tend to accumulate fat in the abdomen and flanks.
As humans age, fat is redistributed. Muscle mass declines, tissues lose their elasticity, and the percentage of body fat increases. Sjöstrom notes that from infancy until approximately puberty, adipose tissue develops by multiplication of fat cells.  At approximately the onset of puberty, fat cell division ceases, and further increase in adipose tissue volume is caused by an increase in the size of individual fat cells.
Most flankoplasty procedures are performed on patients who are mildly to morbidly obese or who have lost a large amount of weight. However, about 15% of the author’s patients are of a normal weight but have very poor skin tone.
An estimated 30-50% of the variability in body fat is determined genetically. Environmental and nutritional factors also are important determinants of body fat stores. Drugs, including phenothiazines, antidepressants, antiepileptics, steroids, antiandrogens, and antihypertensives, have been associated with increased body weight.
The anatomy of the skin and subcutaneous tissue of the lower extremity varies greatly. The skin over the buttock is thick and covers a thick layer of subcutaneous fat (see the image below). Multiple diffuse fibrous septa traverse from the gluteal fascia to the skin. They are especially dense in the area of the gluteal fold. Cutting these during a buttock lift leads to effacement of the gluteal fold.
The skin overlying the greater trochanter is also thick, but there is less subcutaneous fat. This skin is densely adherent to the deep tissues and is recognized as an area that may need to be released during thigh lifts.
Medial thigh skin is thinner than lateral thigh skin and is attached more loosely to the underlying fascia. It also is more prone to rhytid formation, especially after weight loss or as the patient ages.
Knowledge of the cutaneous circulation is important, especially with regard to avoiding skin necrosis when large areas of skin are being undermined. 
The buttock skin is supplied from vertical perforators that originate in the gluteal muscles. The superior and inferior gluteal arteries supply the gluteal muscles. Fasciocutaneous perforators originating in the quadriceps supply the skin of the anterior thigh. Fasciocutaneous perforators from the quadriceps and tensor fascia lata muscles supply the skin of the lateral thigh. Finally, the skin of the medial thigh is supplied through fasciocutaneous perforators from the femoral artery and perforators from the adductor magnus and the gracilis muscles.