THE BURST PHENOMENON, AN ANIMAL-MODEL SIMULATING THE LONG-TERM TISSUE-RESPONSE ON PLLA INTERLOCKING NAILS

In this in vivo study, low-molecular-weight as-polymerized PLLA powder was placed in the medullary cavity of a porcine femur in order to stu dy the tissue reaction on predegradated PLLA. An attempt was made to s imulate the longterm degradation of a large PLLA implant. This phase c an be characterized by the release of PLLA particles and acid compound s from a heterogeneously degrading PLLA implant into the surrounding t issues. The clinical consequences and tissue response were studied. Th e clinical recovery of the experimental animals was favorable. No sign s of clinical inflammation could be detected during the eight-week fol low-up period. Histological analysis of the bone/PLLA interface showed signs of a mild inflammatory tissue response. (C) 1996 John Wiley & S ons, Inc.