Comparison of the Effects of Acellular Dermal Matrix and Montelukast on Radiation-Induced Peri-implant Capsular Formation in Rabbits.

[PURPOSE] Capsular contracture (CC) is a troublesome complication after breast surgery with breast implants, and the risk increases in breast cancer patients after radiotherapy. Studies investigating leukotriene antagonists (eg, montelukast, zafirlukast) found that the acellular dermal matrix (ADM) can help prevent CC. We aimed to compare the effects of ADM and montelukast on CC after irradiation.

[METHODS] Eighteen New Zealand white rabbits were randomly divided into 3 groups of 6 each. Miniature cohesive gel implants were inserted into the pocket under the latissimus dorsi muscle. The lateral part was uncovered by the latissimus dorsi muscle. Six animals were included in the control group. In experimental group A (EG-A) (n = 6), the site was partially wrapped with ADM but not covered with muscle. Montelukast (Singulair, 0.2 mg/kg) was administered in experimental group B (EG-B) (n = 6) daily. Groups were irradiated at postoperative day 21 with Co-60 γ rays (25 Gy, single fraction) at the peri-implant area. Rabbits were sacrificed 12 weeks after surgery; implants with peri-implant capsule were harvested. Capsule thickness, collagen pattern, myofibroblast, and transforming growth factor (TGF) β1/2 levels in the peri-implant capsule were evaluated.

[RESULTS] On histological evaluation, the capsule was thinner on the lateral aspect (covered with ADM) in EG-A (P = 0.004) and the entire capsule in EG-B (P = 0.004) than in the control group. However, there was no significant difference between EG-A and EG-B (P = 0.073). The collagen distribution pattern was more parallel with low density in the lateral capsular aspect in EG-A, but in the entire capsule in EG-B. The myofibroblast amount (EG-A, P = 0.031; EG-B, P = 0.016) and levels of TGF-β1 and TGF-β2 were reduced in the experimental groups (TGF-β1, EG-A, P = 0.019; TGF-β1, EG-B, P = 0.045; TGF-β2, EG-A, P = 0.018; TGF-β2, EG-B, P = 0.022). There was no significant difference between EG-A and EG-B (myofibroblast, P = 0.201; TGF-β1, P = 0.665; TGF-β2, P = 0.665).

[CONCLUSIONS] Acellular dermal matrix and montelukast have a prophylactic effect for CC even when the breast is irradiated. There was no significant difference between ADM and montelukast in preventing capsular formation. The difference is that ADM will only have the effect of covering the capsular formation with ADM and montelukast can cause systemic effects or complications.