Myofibroblasts and capsular tissue tension in breast capsular contracture.

BACKGROUND: This study aimed to observe the relationship between the number of myofibroblasts, the tensile strength of the breast implant capsule, and the degree of breast capsular contracture.
METHODS: The study enrolled 21 women with 31 capsular contractures after aesthetic breast augmentation. The capsular tissue specimens were obtained during capsulectomy, open capsulotomy, and other revisional procedures. The tensile strength of capsular tissues (1 × 3 cm) was measured by tensiometer. The capsular tissues were immunostained by alpha smooth muscle actin, and the immunostained myofibroblasts all were counted on a 2.5-mm length of the capsule.
RESULTS: Myofibroblasts were detected in 22 (71%) of 31 specimens. The myofibroblasts were on the outer layer of the capsule and made up 7.3% to 50% (average, 26.9% ± 12.7%) of the capsule thickness. The number of myofibroblasts varied according to the degree of capsular contracture, but grades 2, 3, and 4 contracture did not differ significantly (p = 0.102). The average tensile strength of the capsule was 44 ± 38 N. Tensile strength was the lowest for grade 2 (27.0 ± 22.2 N), increased for grade 3 (38.0 ± 22.6 N), and was highest for grade 4 (66.5 ± 55.4 N; p = 0.044) contracture. The tensile strength of the capsule correlated positively with the degree of capsular contracture (p = 0.029).
CONCLUSION: The tensile strength of breast capsules correlated with the degree of capsular contracture. The authors think myofibroblasts appear during an active phase of wound contraction and diminish when the wound has matured.