PURPOSE: To evaluate two bioprostheses derived from bovine pericardium, one cross-linked (Peri-Guard®) and the other non cross-linked (Veritas®), and to compare them with human dermal matrix (Alloderm®) and porcine dermal collagen (Permacol®) for abdominal wall repair in the rat.
Methods: The four bioprostheses were tested in acute and chronic hernia models. One involved acute repair of a 3x3 cm midline full-thickness defect and another, two similar defects per animal lateral to the midline. In another group the defect was left untreated for 21 days to achieve a mature status and was then repaired. The prosthetic materials were either sutured to the edge of the defect (inlay) or placed as an underlay with surgical tacks. Evaluation at 3 and 6 months included hernia size, prosthesis thickness, tensile strength (gram force, gf), abdominal wall-prosthesis breaking strength, histology, and adhesion formation, expressed as the percent area of mesh surface involved.
Results: All the prostheses had lesser adhesion coverage compared to previous findings with polypropylene mesh. Alloderm had the least. Permacol and Peri-Guard showed greater tensile strength than the other two prostheses. Significant defect contraction followed repair with Veritas (mean area - minus 3.29 cm2), while Alloderm stretched (mean area - plus 0.84 cm2). Permacol and Peri-Guard did not change. Marked bulging was observed at 6 months with Alloderm. The prosthesis thickness diminished significantly at 6 months for Veritas and Alloderm so much so that they were translucent. All prostheses had cellular ingrowth and neovascularization by 3 months. No significant differences were found in prosthesis-abdominal wall tensile strength nor did inlay versus underlay influence this parameter. Operative site infection occurred in 6 animals (5 Peri-Guard, 1 Veritas), and overlying skin ulceration in 6 (6 Peri-Guard).
Conclusions: Permacol provided a strong and durable repair in two different ventral hernia models for up to 6 months in the rat. Peri-Guard was equally strong but prone to infection and skin ulceration. Veritas and Alloderm had much reduced tensile strength associated with marked thinning, and with hernia bulging of Alloderm. All four prostheses were firmly incorporated into the abdominal wall.
Results.

	Adhesion Formation (%)		Tensile Strength(prosthesis, gf)		Tensile Strength(prosthesis-abdominal wall, gf)
	3m	6m	3m	6m	3m	6m
Permacol (n= 10)	56	47	1199	2596	702	542
Peri-Guard (n= 25)	43	25	2912	2025	688	770
Alloderm (n= 10)	11	25	1816	736	780	711
Veritas (n= 23)	14	39	1192	743	1126	615