Bovine versus Porcine Acellular Dermal Matrix: A Comparison of Mechanical Properties

Abstract

Background: Porcine and bovine acellular dermal matrices (PADM and BADM, respectively) are the most commonly used biologic meshes for ventral hernia repair. A previous study suggests a higher rate of intraoperative device failures using PADM than BADM. We hypothesize that this difference is, in part, related to intrinsic mechanical properties of the matrix substrate and source material. The following study directly compares these 2 matrices to identify any potential differences in mechanical properties that may relate to clinical outcomes.

Methods: Sections of PADM (Strattice; Lifecell, Branchburg, N.J.) and BADM (SurgiMend; TEI Biosciences, Boston, Mass.) were subjected to a series of biomechanical tests, including suture retention, tear strength, and uniaxial tensile strength. Results were collected and compared statistically.

Results: In all parameters, BADM exhibited a superior mechanical strength profile compared with PADM of similar thickness. Increased BADM thickness correlated with increased mechanical strength. In suture tear-through testing with steel wire, failure of the steel wire occurred in the 4-mm-thick BADM, whereas the matrix material failed in all other thicknesses of BADM and PADM.

Conclusions: Before implantation, BADM is inherently stronger than PADM at equivalent thicknesses and considerably stronger at increased thicknesses. These results corroborate clinical data from a previous study in which PADM was associated with a higher intraoperative device failure rate. Although numerous properties of acellular dermal matrix contribute to clinical outcomes, surgeons should consider initial mechanical strength properties when choosing acellular dermal matrices for load-bearing applications such as hernia repair.

Fig. 2.

Tensile stress and stiffness of PADM and BADM by thickness. The average tensile stress and modulus were similar between all materials tested and not statistically different.

Fig. 1.

Ultimate tensile strength and suture retention strength followed similar trends. BADM was statistically significantly (P < 0.05) greater for BADM than PADM in both parameters and increased with thickness. *Indicates P < 0.05 significant differences of BADM compared with PADM. †Excludes 33% of test samples where steel wire broke first. ‡The steel wire broke in every BADM 4.0 sample, and therefore, suture retention strength could not be calculated.

Fig. 3.

Images of suture retention testing failure mechanism for BADM and PADM. The stainless steel wire cut through BADM (~2.0 mm) at a high enough force. However, PADM at a much lower force consistently and repeatedly tore obliquely as imaged above. The direction of the pull through was not parallel to that of the suture force applied and seemed as more of a tearing mechanism than a cut. For thicker BADM, the stainless steel suture broke before pulling from the material.

Fig. 4.

The tear resistance of BADM was significantly higher (P < 0.05) than PADM of equal thickness and the tear resistance increased linearly with increasing BADM thickness.