Quantitative monitoring of capsular contraction around smooth and textured implants.

The purpose of this study was to assess the efficacy of textured silicone implants in reducing the incidence of capsular contracture. Each of 10 female New Zealand, albino rabbits received 2 saline-filled implants, 1 on either side of the lateral chest wall. The surface of 1 implant was smooth silicone, whereas the other implant's surface was textured silicone. Magnetic resonance imaging (MRI) scans of the implants were performed at 0, 9, 17, 26, 34, and 40 weeks after implantation. Data from the MRI scans were used to calculate the effective surface area of implants at each analysis interval. This technique provided a noninvasive method of monitoring implant contraction as a function of time. Eight rabbits completed the study. Four of 8 smooth implants developed contractures, whereas none of the textured implants developed contracture. For the 4 smooth implants that developed contractures, MRI scans calculated 72 +/- 12% contraction at 17 weeks, but the Baker palpation test detected only mild firmness. From 17 to 40 weeks, the mean percentage of contraction for these implants changed minimally, but their mean Baker score increased from mild to severe (II to IV). Quantitative data from MRI scans were much more predictive of final implant contraction than palpation (Baker test), applanation tonometry, or indentation tonometry. The latter two tests only detected the final stages of severe implant contraction.

Development of independent vessel security after ligation with absorbable sutures or clips.

The external jugular vein and the contralateral carotid artery in each of 59 rabbits were ligated with either sutures or absorbable clips and then divided. After 0, 1, 2, 4, 7, or 14 days following ligation, the suture or clip was removed, and the vessel's resistance to leakage was quantitated. When the absorbable clips were removed from arteries after 1 day, their mean resistance pressure prior to leakage was 171 +/- 46 mm Hg; in contrast, arteries ligated with a suture did not achieve independent security until after 4 days. At 4 days, the mean pressure prior to leakage of arteries with the suture removed was only 88 +/- 49 mm Hg. Similar results were obtained with veins. The difference in vessel security was attributed to the significant increase in the width of the vessel wall compressed when an absorbable clip was utilized compared with a strand of suture.

Early tissue reaction to textured breast implant surfaces.

Capsular contracture around breast implants with smooth surfaces continues to be an unpredictable complication. Some surgeons believe that silicone implants covered with porous polyurethane foam have a lowered potential to contract. These textured implants are not as biocompatible as silicone. Recently, silicone implants with textured surfaces have been introduced with the hope that the incidence of unacceptable implant contracture will be reduced. Using a rat implant model, the tissue reaction to textured implant surfaces was assessed. The implant surfaces evaluated were Silastic II, Siltex, MISTI, Biocell, Silastic MSI, and Même. Disks of each implant material were implanted under the dorsal skin of rats for a period of 28 days. Each implant with its surrounding tissue was excised, processed for histological analysis, and assessed for the tissue's response to the implant with particular emphasis on the formation of a continuous collagen capsule. The results indicated that the magnitude of surface texturing influenced the development of a complete capsule. Implant surfaces with a texture of less than 150 microns in height or depth (Silastic II, Siltex, and MISTI) resulted in the formation of complete capsules. An implant (Biocell) with irregular texturing (200-350 microns) produced an organized capsule over most of its surface with localized interruptions of the capsule at the sites of its deepest cavities. Implant surfaces with texturing that exceeded 350 microns in height or depth (Silastic MSI and Même) resulted in inhibition of the formation of a continuous capsule during this 28-day study.