Hypothesis / aims of study
This original study aimed to evaluate the efficacy and safety of MatriDerm®, a bovine-derived acellular dermal matrix graft, for penile augmentation in a rabbit model, and to assess penile girth increases, potential complications, and histopathological alterations.
Study design, materials and methods
: Thirteen male New Zealand white rabbits were divided into two groups; seven underwent penile augmentation with MatriDerm®, and six served as sham group. One subject from each group died during follow-up and were excluded from the study. Rabbits were anesthetized and prepared under sterile conditions. After marking and baseline measurements of penile dimensions. A circumferential incision was made, the penis was degloved to Buck’s fascia, and a 1 mm thickness MatriDerm® graft was wrapped around the penile shaft (excluding the urethra) and secured. The skin was closed. The same procedure was performed in the sham group without graft placement. Artificial erection was induced to assess preoperative and postoperative chordee. After an 8-week follow-up period, penectomy was performed on all subjects. Penile measurements (incision circumference, penile root circumference, dorsal and ventral lengths) were recorded preoperatively, intraoperatively, and 8 weeks post-operatively. Histopathological analysis of penectomy specimens assessed skin-tunica albuginea distance, collagen layer thickness, vascular density (via CD31 staining), and fibroblast density (via α-SMA staining). The fibroblast density in the tissue was scored on the basis of the staining intensity and proportion of positively stained stromal cells [2]. CD31-positive vessels were counted, and vascular density was calculated as the number of vessels per high-power field [2].
Results
Compared to the sham group, the MatriDerm® group showed a significant increase (49.22%) in penile incision circumference at 8 weeks post-surgery (p=0.005). No differences were found in penile root circumference or length between groups. One penile deformity occurred in the MatriDerm® group, though not statistically significant (p=0.545) (Table 1). Histopathological findings showed greater skin-tunica albuginea distance (8.50±1.47 mm vs. 3.50±1.30 mm, p<0.001), collagen layer thickness (2.98±0.97 mm vs. 1.28±0.30 mm, p=0.005), vascular density (13.50±2.42 vs. 5.60±1.81, p<0.001), and fibroblast density (all scores 3 vs. 1, p=0.002) in the MatriDerm® group (Table 2). By the end of the 8th postoperative week, MatriDerm® had been completely absorbed, with no residual graft material identified in any of the penectomy specimens. Furthermore, none of the tissue samples demonstrated cellular changes suggestive of inflammation or a foreign body reaction.
Interpretation of results
In rabbits undergoing penile augmentation surgery with Matriderm®, a significant increase in penile girth was achieved, as demonstrated by histopathological measurements of the skin-tunica albuginea distance. Compared with the sham group, no significant difference was observed in terms of chordee development. Histopathological examination at the end of the 8th week revealed complete absorption of Matriderm®, with replacement by fibroblasts, and no findings suggestive of tissue reaction or inflammation were identified. Additionally, vascular density was found to be increased compared with the sham group.