Plates for internal fixation fabricated from biodegradable polymers degrade
via an autocatalytic route. When they are used in bone implants of signifi
cant size and thickness, hollowing of the implant may occur while the overa
ll dimensions appear unchanged. We hypothesized that incorporation of a cro
ss-linked polypropylene fumarate matrix into polylactide-co-glycolide bone
plates may provide an internal molecular network which prevents implant col
lapse. Cross-linking reagents of varying hydrophilicity including N-vinylpy
rrolidone (VP), hydroxyethylmethacrylate (HEMA), and ethyleneglycol dimetha
crylate (EGDMA) were employed. With the objective of determining the most b
iocompatible and structurally sound composition for molecular reinforcement
, we investigated tissue responses in both subcutaneous and orthotopic rode
nt implantation models in relation to maintenance of implant integrity by h
istologic, histomorphometric, and stereomicroscopic analysis. Results showe
d that tissue responses were correlated with dimensional stability of the i
mplants. The most favorable results were seen with the hydrophobic cross-li
nker EGDMA; this may have been related to the initial reduction of the wate
r uptake by the implant. Cross-linking of polypropylene fumarate with EGDMA
within a polylactide-co-glycolide bone plate may offer a means to maintain
excellent biocompatibility while improving dimensional stability of biodeg
radable bone plates.