To assess the effect of hyaluronan on meniscus injury and repair, we had 35
mature New Zealand White rabbits undergo bilateral meniscus injury and rep
air (19 in the peripheral region, and 16 in the inner region). A longitudin
al tear was created in the medial meniscus and repaired with horizontally p
laced nylon sutures. The left knee joint received intraarticular injections
of hyaluronan 1 week after surgery and once a week for 5 weeks. The right
knees were injected with phosphate-buffered saline (the carrier vehicle of
the hyaluronan). Twelve weeks after repair, tears in the peripheral region
showed gross and histologic evidence of healing, with no difference between
the vehicle- and hyaluronan-treated menisci. Biochemically, the ratio of r
educible collagen cross-links in the hyaluronan-treated menisci was signifi
cantly higher than in the vehicle-treated menisci, indicating greater level
of collagen remodeling. Biomechanically the vehicle- and hyaluronan-treate
d menisci demonstrated similarly high tearing load and fracture toughness.
In the inner region, poor healing response was observed grossly and histolo
gically in both treatment groups. Water content in the hyaluronan-treated m
enisci was significantly lower than in the vehicle-treated menisci, indicat
ing a lower level of swelling. Hyaluronan treatment stimulated collagen rem
odeling in the peripheral region and inhibited swelling of the meniscus rep
aired in the inner region.