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Background: Immediate single-stage direct-to-implant breast reconstruction with acellular dermal matrix(ADM) is a popular method for breast reconstruction. Subpectoral placement of the implant is often favored and usually results in a desirable cosmetic outcome. However, drawbacks of subpectoral placement include greater postoperative pain and animation deformities. The authors report their experience with single-stage direct-to-implant breast reconstruction with prosthetic placement in both the prepectoral plane and the subpectoral plane.
Methods: A retrospective review of a single surgeons experience was performed for immediate single-stage implant reconstruction with ADM between 2011 and 2015. Statistical analysis was performed to evaluate differences between the subpectoral versus prepectoral group and the association between pre-operative characteristics and post-operative complications. All tests were two-tailed with a significance level of p< 0.05.
Results: The study sample consisted of 38 subjects representing reconstruction of 61 breasts(41 subpectoral and 20 prepectoral). With the exception of body mass index(24.8±4.9 subpectoral vs. 35.9±8.6 prepectoral, p<0.01), pre-operative characteristics were statistically similar between the subpectoral and prepectoral group including age, smoking, diabetes, prior breast surgery, and radiation and/or chemotherapy(Table 1). The prepectoral group tended to receive larger implants(p<0.01), but the type of mastectomy, type of nodal exploration, and blood loss did not differ significantly between the two groups(Table 2). At the median follow-up of 283 days, the overall rate of complications between the subpectoral and prepectoral group were similar. Specific complications including 30-day readmission, dehiscence, infection, mastectomy skin flap necrosis, and seroma were statistically comparable between the two groups(Table 3), while the incidence of capsular contracture was significantly higher in the subpectoral group (17.1% vs. 0%; p=0.049). In this cohort, prior breast surgery was associated with a higher rate of dehiscence and necrosis, while capsular contracture was associated with adjuvant chemotherapy (Table 4).
Conclusion: The present study demonstrates that immediate prepectoral reconstruction can be performed with results that are non-inferior to the traditional subpectoral approach in terms of post-operative complications and may offer the cosmetic benefits of prepectoral placement. The rate of capsular contracture was in fact lower in the prepectoral group. A larger cohort is needed to corroborate the present conclusions.

Table 1: Pre-operative Characteristics
	All Patients	Prepectoral Implant	Subpectoral Implant	p-value
Number of cases	38	25	13
Number of breasts	61	41	20
Age (y, )	51.9±14.1	51.3±10.9	53.1±19.2	0.771
BMI (kg/m^2, )	28.6±8.2	24.8±4.9	35.9±8.6	<0.01
Smoking (%)	14 (36.8)	7 (28.0)	7 (53.9)	0.117
Diabetes mellitus (%)	4 (10.5)	3 (12.0)	1 (7.7)	0.681
Prior breast surgery (%)	7 (18.4)	4 (16.0)	3 (23.1)	0.593
Radiation (%)
Neoadjuvant	1 (2.6)	1 (4.0)	0 (0)	0.465
Adjuvant	6 (15.8)	4 (16.0)	2 (15.4)	0.961
Chemotherapy (%)
Neoadjuvant	10 (26.3)	6 (24.0)	4 (30.8)	0.653
Adjuvant	6 (15.8)	5 (20.0)	1 (7.7)	0.324

Table 2: Operative Characteristics
	All Patients	Subpectoral Implant	Prepectoral Implant	p-value
Indication (%)
Prophylactic	7 (18.4)	5 (20.0)	2 (15.4)
Breast cancer	31 (81.6)	20 (80.0)	11 (84.6)	0.728
Type of mastectomy (%)
Nipple sparing	8 (21.1)	6 (24.0)	2 (15.4)
Simple	27 (71.0)	16 (64.0)	11 (84.6)
Modified	3 (7.9)	3 (12.0)	0 (0)	0.305
Side (%)
Unilateral	15 (39.5)	9 (36.0)	6 (46.2)
Bilateral	23 (60.5)	16 (64.0)	7 (53.8)	0.545
Node (%)
Sentinal node biopsy	25 (65.8)	16 (64.0)	9 (69.2)
Sentinal node dissection	4 (10.5)	4 (16.0)	0 (0)	0.282
Estimated blood loss (ml, )	100.3±73.5	94.8±70.2	110.8±81.3	0.532
Implant size (ml, )	423.9±141.4	380.4±122.9	507.7±141.0	<0.01
Soft tissue support (%)
Alloderm	35 (92.1)	25 (100)	10 (76.9)
Autoderm	3 (7.1)	0 (0)	3 (23.1)	0.012

Table 3: Postoperative Outcome Data
	All Patients	Subpectoral Implant	Prepectoral Implant	p-value
Days of follow-up (median(Q1,Q3))	283 (140, 589)	397 (193, 644)	161 (208, 229)	0.031
Readmission within 30 days (%)	6 (15.8)	4 (16.0)	2 (15.4)	0.961
Incidence of complications (% per breast)	13 (21.3)	10 (24.4)	3 (15.0)	0.401
Dehiscence	2 (3.3)	1 (2.4)	1 (5.0)	0.598
Infection	4 (6.6)	3 (7.3)	1 (5.0)	0.731
Necrosis	3 (4.9)	2 (4.9)	1 (5.0)	0.984
Seroma	4 (6.6)	2 (4.9)	2 (10.0)	0.448
Capsular contracture	7 (11.5)	7 (17.1)	0 (0)	0.049
Complication requiring explantation or exchange (%)	12 (19.7)	9 (21.9)	3 (15.0)	0.521

Table 4: Association of Pre-operative Characteristics and Postoperative Complication by p-values
	All-cause Complications	Dehiscence	Infection	Necrosis	Seroma	Capsular Contracture
Age	0.822	0.523	0.924	0.837	0.954	0.648
BMI	0.691	0.560	0.431	0.245	0.058	0.604
Smoking	0.391	0.267	0.546	0.265	0.094	0.615
Diabetes	0.127	0.618	0.468	0.536	0.468	0.315
Prior breast surgery	0.157	0.030	0.315	0.025	0.085	0.443
Radiation
Neoadjuvant	0.160	0.811	0.728	0.767	0.728	0.184
Adjuvant	0.324	0.529	0.360	0.435	0.360	0.904
Chemotherapy
Neoadjuvant	0.060	0.385	0.950	0.774	0.950	0.080
Adjuvant	0.068	0.529	0.593	0.385	0.593	0.030