Introduction

The shape and definition of the buttocks have long been a focal point in the historical depiction of the human form. ^{1 , 2} While traditionally emphasized in the female figure, the gluteal region is similarly a critical component of the male aesthetic ideal, responsible for accentuating the masculine torso and defining the lower limbs. Buttock augmentation was initially translated from breast enhancement when Bartels et al. ³ first reported using round silicone gel breast implants to correct gluteal asymmetry in 1969. As this surgery became adopted as a cosmetic procedure, ^{4 , 5} different techniques were developed with regard to implant placement and surgical approach. The shape and design of gluteal implants also evolved alongside these techniques to include a variety of anatomical silicone cohesive gel and solid elastomer options.

Initial reports of gluteal augmentation advocated placement of implants in the subcutaneous plane. In 1979, González-Ulloa6 described implant placement just over the gluteal aponeurosis. The submuscular approach was later introduced by Robles et al. ⁷ preventing distortion of the fasciocutaneous aponeurotic extensions, although limited to smaller implant sizes to avoid damaging deeper neurovascular structures. More recent alterations to this technique have included intramuscular implant placement, as described by Vergara et al. ^{8 , 9} as well as implant placement in the subfascial plane, introduced by de la Peña et al. ^{10 , 11} Alternate approaches, such as through paramedian incisions, ⁷ have also been popularized to decrease visible scarring. While each of these techniques has its own benefits and drawbacks (Table 39.1), these modifications have overall aimed to optimize cosmetic outcomes while avoiding damage to surrounding structures and minimizing prosthesis-related complications. ^{12 , 13} A variety of different implantation techniques continues to be used today, ¹⁴ most commonly involving intramuscular or subfascial implant placement. The intramuscular technique is discussed in this chapter as the authors preferred technique to maximize implant coverage, limit implant migration, circumvent restrictions caused by deeper neurovascular structures, and prevent overlying contour deformities.

Physical Evaluation

1. 
   

   While examining and marking the patient, the physician should be sitting down and the patient is standing.

   
   
2. 
   

   Assess gluteal volume, projection, ptosis, and skin and fascial laxity in relation to aesthetic landmarks including the sacral triangle, lateral depressions, and infragluteal folds.

   
   
3. 
   

   Evaluate the need for overall volume reduction or addition (or both).

   
   
4. 
   

   Use a template to mark out the proposed implant pocket and estimate potential implant shapes and sizes.

   
   
5. 
   

   Determine the appropriate incision placement with regard to implant shape, size, and individual gluteal contour or anatomy.

   
   
6. 
   

   Assess the patient’s goals and incorporate measurements and observations from examination to formulate a realistic and feasible plan with the patient.

   
   
7. 
   

   Any asymmetry should be carefully examined, discussed with the patient, and documented in writing and with photography preoperatively.

   
   
8. 
   

   Identify patients who will benefit from Body- Banking and MuscleShadowing and incorporate into preoperative markings.

   
   
9. 
   

   Examine the lower trunk, hips, and thighs to determine whether contouring of the surrounding structures will be needed to attain aesthetic goals.

Anatomy

A thorough understanding of the muscular anatomy, fascial planes, and neurovascular structures of the gluteal region is paramount for ensuring the proper placement of gluteal implants, achieving the optimal aesthetic result, and avoiding complications. The gluteal region is comprised of structures posterior to the pelvic girdle that are bound by the iliac crests superiorly, the greater trochanters of the femurs laterally, the gluteal folds inferiorly, and paired on either side of the intergluteal cleft in the midline. This region contains powerful pairs of muscles that can be divided into superficial and deep groups, primarily responsible for abduction or extension and lateral rotation of the lower limb, respectively.

External landmarks include the iliac crests, posterior superior iliac spines (PSIS), the sacral triangle, and the distal tip of the coccyx, which usually lies around 3 to 4 cm above the anus. The subcutaneous tissue in this region is relatively thick over each buttock and is enveloped by a superficial fascial system (SFS) containing sensory nerves. This layer, however, thins significantly toward the midline near the sacrum. The deep fascia is a critical structure during dissection that envelopes the gluteus maximus as well as the gluteus medius (superolaterally), extending from the iliac crest to the sacrum medially, and continuous with the deep fascia of the thigh inferiorly. This fascia is also contiguous with the gluteal aponeurosis superiorly, or the medial extension of the tensor fascia lata (TFL), which contains multiple musculofascial attachments near its posterior border.

The superficial compartment musculature consists of three glutei muscles and the TFL. The most superficial and posterior of these is the gluteus maximus, a large, broad, rectangular muscle originating from the posterior surface of the ilium, sacrum, and coccyx and running inferolaterally to insert on the iliotibial (IT) tract and greater tuberosity of the femur.

The fibers of gluteus maximus are identified running transversely and cover the inferior aspect of the gluteus medius, a smaller fan-shaped muscle and abductor of the hip that runs from gluteal surface of the ilium to the greater trochanter. The fibers of the gluteus medius, on the other hand, run vertically, and can be easily differentiated in a distinct plane from gluteus maximus superiorly, but blend together with fibers of the gluteus maximus inferiorly. Immediately deep to the gluteus medius is the gluteus minimus, whose fibers similarly run in a superior–inferior direction from the gluteal surface of the ileum to the greater trochanter. Laterally, the TFL extends from the iliac crest, just posterior to the anterior superior iliac spine to insert onto the IT band.

The deep group of muscles consists of smaller, lateral rotators of the hip, including the piriformis most superiorly, followed by the obturator internus flanked by the paired gemelli, and the pronator quadratus proceeding inferiorly. These muscles are not routinely encountered but can serve as important landmarks for neurovascular structures exiting the pelvis.

Critical structures in the gluteal region include the gluteal vessels and nerves as well as the sciatic nerve, which should be deep to the plane of dissection for intramuscular implant insertion. The superior gluteal nerve innervates the gluteus medius, gluteus maximus, and TFL and is accompanied by the superior gluteal artery, exiting superior to the piriformis to run between the gluteus medius and minimus. The course of the superior gluteal artery can be found along a line between the PSIS and the greater trochanter. The inferior gluteal nerve emerges inferior to the piriformis, similarly running with the inferior gluteal artery along the deep aspect of the gluteus maximus. The sciatic nerve exits the greater sciatic foramen, deep to the piriformis, and courses inferolaterally over the deep lateral rotators of the hip. The nerve usually runs lateral to the pelvic acetabulum, which can be palpated intraoperatively for orientation ( Fig. 39.1 , Fig. 39.2 ).

Technical Steps for Gluteal Augmentation with Implants

With the patient standing, mark the important anatomical landmarks of the gluteal region including the midline, sacral triangle, iliac crests, and infragluteal creases bilaterally. The midline incision is then marked in the gluteal cleft at the level of the coccyx or slightly lower and extending 5 to 7 cm superiorly. With the gluteus muscles flexed as well as in repose, the muscle implant groups are marked, and the proposed dimensions of the implant pockets are subsequently drawn out using a cookie cutter. Last, any areas for augmentation with BodyBanking or lateral MuscleShadowing are marked ( Fig. 39.3 ; Table 39.2, Table 39.3 ).

In the operating room, the patient is prepped over the buttocks, back, and thighs while standing, and sterile stockinettes are placed over bilateral lower extremity Venodynes. The patient subsequently lies supine on the operating table over sterile drapes with a transversely oriented sterile Mayo stand cover to function as a draw sheet. General anesthesia with endotracheal intubation is preferred, as it allows for paralysis, which greatly aids the intramuscular dissection of the gluteus maximus. After intubation, the patient is rotated into the prone position using the sterile draw sheet. A Betadine-soaked anal pack is then placed and secured with a 4–0 nylon suture. An Ioban antimicrobial drape is then placed over the anus to seal off the perianal area for the rest of the case, and the remainder of the patient is draped appropriately (a 10 × 10 cm piece of Ioban should be saved for “no-touch” implant insertion). A single dose of preoperative antibiotics is given prior to incision ( Fig. 39.4 ).

The incision is injected with 2% lidocaine with 1:100,000 epinephrine, and around 75 to 100 cc of tumescent fluid is injected into the gluteus maximus with a blunt tumescent cannula, which is allowed to dwell for at least 10 minutes prior to dissection ( Fig. 39.5 ). It is important to allow epinephrine adequate time to take effect, as significant bleeding can make the intramuscular dissection cumbersome. Furthermore, one should always bear in mind the course of the inferior and superior gluteal neurovasculature in this step as well as not to tumesce too deep to avoid injury to the sciatic nerve.

Note: These are routine preoperative measurements that should be included in every patient assessment.

Note: These are routine postoperative measurements and notes that should be charted.

The skin is incised, and dissection is tunneled subcutaneously toward the medial (flexor) and lateral (extensor) muscle groups while concomitantly achieving meticulous hemostasis. The deep fascia overlying the gluteus maximus is significantly more superficial near the midline, so superficial dissection should proceed slowly and carefully as to ensure that the fascia and muscle are not inadvertently entered in the wrong area. The gluteal fascia is then incised longitudinally around 2 cm from the intergluteal cleft.

Intramuscular dissection is carried to an intermediate depth within the gluteus maximus using electrocautery to leave around 1.5 cm of muscle coverage superficial to the implant pocket ( Fig. 39.6 ). On the other hand, dissection must not be carried too deep as to avoid injuring or even exposing the sciatic nerve. Communication of the implant pocket with the underlying nerve can lead to significant irritation postoperatively. Intramuscular dissection then proceeds bluntly in a lateral direction oriented along the transverse fibers of the gluteus maximus and is similarly carried superiorly and inferiorly. A suction tip or malleable instrument is utilized to provide countertension and facilitate dissection. The surgeon’s assistant is crucial for fluid and efficient dissection by providing retraction with incrementally larger retractors to optimize visualization and maintain countertension. A headlight can additionally be helpful as the dissection proceeds further. Again, the location of the inferior gluteal artery and its perforators should be kept in mind to minimize any potential source of bleeding, and hemostasis should be checked after dissection to ensure a completely dry field.

Further pocket adjustments can be made at this time depending on the patient’s body habitus and desired implant size. Trimming the muscle medially and laterally can maximize midgluteal projection to allow for a more elongated and athletic contour in men. The dissection is then repeated on the contralateral side in a similar fashion using the same central access incision. For those not yet comfortable with the procedure, utilizing two incisions on either side of the central gluteal cleft allows for less restricted access and dissection. The senior author prefers not to use any drains whatsoever. However, a single Jackson–Pratt drain may be placed in each implant pocket and brought out superomedially in the central gluteal fold through a separate stab incision ( Fig. 39.7 ).

With regard to the implant choice, the senior author prefers to use MuscleGel gluteal implants. While multiple types of implants may be appropriate, we recommend using gel implants that are not firm, but rather can mimic the quality of relaxed muscle without too much difficulty. In addition, larger implants are more difficult to handle and implicitly require more extensive dissection. Shaped implants are also more difficult to insert and position properly to avoid rotation. It is therefore recommended that smaller (<300cc), round implants are utilized while initially becoming familiar with this procedure to minimize complications.

Prior to implant insertion, the incision is cleaned with triple antibiotic solution, and the remaining Ioban drape is placed over the incision. All gloves are then changed, and the implant is washed in triple antibiotic solution. The Ioban is incised, and a Keller Funnel may be used, though not required, to insert the implant into the pocket using a “no-touch” technique ( Fig. 39.8 ). After bilateral implants are inserted, the buttocks are examined for shape, size, and symmetry. If any further pocket modifications are needed, gloves are changed, washed in triple antibiotic solution, and the “no-touch” technique is used again for insertion after modifications are complete.

The muscle pockets are first closed using 8 to 10 interrupted 0 or 2–0 Vicryl sutures with large bites of gluteal fascia to ensure a “watertight” closure ( Fig. 39.9 ).

It is imperative that the pocket is closed under absolutely no tension to minimize the risk of postoperative dehiscence. If a tensionless closure is not possible, the implant should be removed, and dissection should be carried further laterally until the muscle edges can be approximated with ease ( Fig. 39.10 ). The SFS is then reapproximated to the deep gluteal fascia centrally, and the bilateral superficial fascial elements are approximated to each other under the incision.

The incision is subsequently closed with a running subcuticular 3–0 Monocryl suture with bipolar buried knots ( Fig. 39.11 ).

Additional sculpting of the soft tissue can be performed at this time as needed. BodyBanking fat grafting to the superior and inferior poles of each buttock narrows the buttock and allows for increased midgluteal projection. MuscleShadowing concavity can also be utilized laterally to further accentuate an athletic contour. After completion of the procedure, 20 cc of 0.5% Marcaine may be injected retrograde into the drains (if they are used) and allowed to sit for 20 minutes prior to applying closed suction devices to improve postoperative analgesia.

Dermabond and Mastisol are applied around the incision, and 1-inch vertical and transverse Steri- Strips are applied across the incision followed by gauze and paper tape. If lateral MuscleShadowing was performed, lateral gluteal concavity recovery supports (BodyBanking buttresses) are placed. The anal pack is removed, and a snug, but not tight, postoperative black garment is placed over the dressings.