Purpose: AlloDerm, an implantable dermal matrix, is gaining increasing acceptance in tissue expander/implant (TE/I) breast reconstruction. By using AlloDerm to create the inferior-lateral portion of an expander pocket, elevation of the serratus anterior muscle/fascia can be avoided, theoretically limiting postoperative musculoskeletal morbidity. Anecdotal evidence suggests that due to the pliability of the dermal matrix, AlloDerm also allows for the injection of greater initial fill volumes and facilitates more rapid post-operative expansion. The primary objective of this study was thus to evaluate the impact of AlloDerm on the rate of tissue expansion in the setting of immediate, TE/I reconstruction.
Methods: A matched, retrospective cohort study was performed. Medical records of consecutive patients who underwent immediate TE/I reconstruction from 2004 –2005 were reviewed. Two patient cohorts were identified: i) patients who underwent TE/I reconstruction with implantable AlloDerm; and ii) patients who underwent standard TE/I reconstruction. Individual patients were matched 1:1 on the basis of: expander size (+/- 100 cc); history of prior irradiation; and, indication for mastectomy (prophylactic/therapeutic). Matched cohorts were compared with respect to: intraoperative expander volume injected (cc), rate of post-operative expansion (cc/ injection); total number of expansions; and, time to completion of expansion (days). The incidence of complications was similarly evaluated in each cohort. Pairwise comparisons were performed using the Wilcoxon sign-rank test for continuous variables and McNemar's test for categorical variables.
Results: In total, 90 immediate TE/I reconstructions were evaluated. Forty-five TE/I reconstructions using implantable AlloDerm were matched to 45 standard TE/I reconstructions. Seven percent of the total cohort had a history of prior irradiation; 35.5% had a prophylactic mastectomy. Median expander size was 500 cc. Intraoperatively, expanders in the AlloDerm and non-AlloDerm cohorts were filled with a mean volume of 223.8 and 201.1 cc, respectively (p=0.180). Expanders were routinely overexpanded to 120% of the expander size. The median number of percutaneous expansions performed was 5 and 6 in the AlloDerm and non-AlloDerm cohorts (p=0.117). Median time to completion of expansion was 64 days in patients who received AlloDerm and 70 days in those who did not (p=0.257). There was no difference in the mean rate of post-operative tissue expansion between the AlloDerm cohort ( 97 cc/injection) and the non-AlloDerm cohorts ( 95 cc/injection; p=0.907). There was similarly no difference in the incidence of complications with or without the use of AlloDerm (p=0.2891). Minor complications occurred in 13.1% (6/45) of cases following AlloDerm implantation [cellulitis (n=3); seroma (n=3); hematoma (n=1)].
Conclusions: While the current study does not address the efficacy of AlloDerm in decreasing morbidity and/or improving aesthetic outcomes in the setting of TE/I reconstruction, these findings indicate that the use of AlloDerm does not increase the rate of tissue expansion following immediate, post-mastectomy expander placement. The use of AlloDerm does not, however, appear to increase the risk of post-operative complications. This suggests that, if an implantable dermal matrix is used at the time of expander placement, additional risks are not incurred.
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