Persistence of polypropylene mesh anisotropy after implantation: an experimental study

Objective To determine whether anisotropy persisted after incorporation into the host, using a standardised rabbit model for abdominal wall reconstruction. Design Investigator-initiated prospective-controlled experimental study. Setting Centre for Surgical Technologies, Medical Faculty KU-Leuven. Sample Fifteen New Zealand White rabbits. Methods In each rabbit, four full thickness primarily repaired abdominal wall defects were covered by a 4 x 5-cm Prolift+M implant (Johnson & Johnson, Norderstedt, Germany), either with the stiffest (n = 6 rabbits) or most elastic (n = 6) direction parallel to the body axis. Prolift+M contains 32 g/m(2) polypropylene, reinforced with polyglecaprone fibres. Harvesting was performed after 30, 60 and 120 days (n = 2 each time-point). The abdominal wall of three unoperated rabbits was used as negative control. Main outcome measures Contraction, compliance and maximal strain and stress determined by uniaxial tensiometry. Results Anisotropy properties persist at lower, more physiological displacements, but not at higher displacements. The stiffness of a mesh-augmented repair in the lower strain range remains above that of native tissue. Eventual mesh contraction was limited to 4.3%. Conclusions Anisotropic properties of Prolift+M persist in vivo and shrinkage is minimal. Compliance of mesh-augmented repair remains less than that of native tissue. The functional consequences of this remain to be studied.