Progress in materials and the design of these implants continues.

More than 100,00 women each year have breast augmentation for reconstruction following mastectomy, for reconstruction following the atrophy of pregnancy, and to enlarge small breasts. The most difficult postoperative problem is the development of capsular contracture from scar formation around the slick implants. In recent years, the development of a urethane open cell foam-cover has led to a dramatic decrease in the incidence of painful capsular contracture. However, the urethane is known to undergo hydrolysis into unknown substances, so its benefits may be temporary at best. Our previous work in texturizing Teflon and silicone rubberfordialysis shunts and other prostheses has led us to the texturizing of the same safe simple silicone substance to allow tissue ingrowth for thinner capsules that cannot contract. Based on promising animal experiments, we have begun implanting these Molecular Impacted Surface Textured Implants (MISTI) prostheses in our patients. FDA registration was achieved in late 1987, and we now have eighty implants in forty patients followed for as long as one year. Although initially only used in patients who were failures of slick implants with recurrent contracture, we are now using them in our routine augmentation patients, and all remain soft.

In 1962, Cronin and Gcrow first published on the use of silicone gel-filled implants for breast reconstruction and augmentation. Initially, these devices were made with Dacron patches to hold them in place. The Dacron was found not only to allow tissue fixation, but to be a source for the incitation of violent scar formation. Many of these early implants became encapsulated promptly and were removed within a few years. Subsequently silicone gel-filled bag implants were used with no fixation patches, and then a saline inflatable prosthesis was popular for several years. The inflatable prosthesis, however, developed fold flaw failures with leaks and generally fell out of favor. A double lumen prosthesis was then developed with a gel filled inner bag surrounded by a second slightly larger silicone bag in which saline and/or some medications might be placed. These are currently used by approximately 20 percent of the plastic surgeons in the United States. The inflatables are still used by approximately 1O percent of the United States plastic surgeons. Most of the rest use the slick surface silicone. Increasing numbers are using textured implants.

We began implementation in patients of texturized silicone implants. These MISTI prostheses are the same simple safe silicone substance but with the outer surface temporarily impacted with a variety of "designer" molecules so that an irregular surface of caves is created to allow some tissue ingrowth. Contact guidance of the scar tissue anchors the host to the prosthesis at this interface. In this way, we decrease the motion between the host and the prosthesis, and decrease that stimulus for scar formation that occurs from repeated trauma to the inner surface of the capsule. Further, if bacteria are lodged on one portion of the textured surface, they can be engulfed and entrapped by the body, whereas a slick implant provides a safe haven for the bacteria and cannot be engulfed by the host defense mechanisms. Our animal experiments have shown that the irregular surface with multiple caves, causing an in and out, up and down path for the fibroblasts, develops a thinner capsule than the same substance with a slick surface. This work has been confirmed bv Taylor and Gibbons. Although the urethane-covered prostheses have been seen to decrease capsular contracture initially, they have been described as difficult to insert and impossible to remove completely. These silicone textured implants can be inserted through the usual incisions: around the nipple, under the breast crease, or in some cases, through the axilia. We have placed them beneath the breast or beneath the pectoralis muscle when indicated.

JU is a 35-year-old female who had a bilateral subcutaneous mastectomy elsewhere. The standard implants became hard, contracted, and painful within a few months. Since then shehas had multiple failures of slick implants, with ruptured implants. Attempts were made to place them under the muscle and over the muscle. When first seen by us eight years after her initial surgery, she had fin-n contracted breasts that consisted of scar, skin. and silicone with no intervening breast, muscle, or fatty tissue. She was in constant pain, was unable to raise her an-ns fully above her head, and could not find a comfortable position to sleep in at night since any pressure on these firm breasts caused her further discomfort.

In this difficult case, we removed as much of the scar tissue as safely could be excised from the posterior walls of the encapsulation. Free silicone was found in the wound from previously broken implants. Several radial slits were produced in the anterior surface to provide for relaxation of this scar capsule without actually removing it. Since the only blood supply to the outer surface of the breast was from the den-noplexus of the skin, no attempt was made to strip this scar capsule from this very thin breast. Double lumen, MISTI implants were placed, and at one-year follow-up the wounds have healed well and the breasts remain soft, pain free, and comfortable. Because of the thin skin and scar, there is an unnatural wrinkling to these breasts when the patient leans to one side or the other that is due to the lack of elasticity in the scar and skin. The patient remains comfortable and we feel that this less than perfect appearance is a reasonable tradeoff for comfortable, soft breasts. In reviewing our ten-year experience with breast augmentation, we have found that some contracture of the breast occurs in approximately 40 percent of the patients with slick implants. One-third of these contractions occur in the first year and one third in the second year; the remaining third is evenly distributed over the next five years. We have no patient who later developed contracture after more than seven years. Although the one-year follow-up reported here is quite early for long-ten-n results, since many of these initial patients were those who had been failures of slick implants in whom capsular contracture could be expected to form in the most rapid fashion, and since they are uniformly soft at this time, it does appear that the silicone textured prosthesis is a promising alternative for the future.