Objective: Long-term assessment of the effect of hyaluronan (HA) on th
e articular cartilage and synovium in an animal knee joint during the
development of osteoarthritis (OA). Design: Sixty mature New Zealand w
hite rabbits underwent unilateral anterior cruciate ligament transecti
on (ACLT) and were divided into two groups. Group 1 (SA) received intr
a-articular injections of 0.3 ml hyaluronan (HA) (i.e., ARTZ, MW: 8x10
(5)) beginning 4 weeks after ACLT, once a week for 5 weeks. Group 2 (S
V) received injections of the vehicle (phosphate buffered saline) in t
he same fashion as with the SA group. The contralateral nonoperated kn
ee served as control. All animals were killed 21 weeks after surgery a
nd their knee joints evaluated by gross morphologic, histologic, histo
morphometric and biochemical analyses. Results: Gross morphological in
spection indicated that the femoral condyles from the knees injected w
ith vehicle suffered more severe cartilage damage than cartilage from
the knees injected with HA. Furthermore, two out of three histomorphom
etric parameters measured in the HA-treated cartilage (i.e., cartilage
thickness and cartilage area which were not statistically different t
han control) provided evidence showing a protective effect of HA on th
e femoral condyles following ACLT. Biochemical analysis showed articul
ar cartilage remaining on the femoral condyles following ACLT to have
similar characteristics to contralateral controls. However, DNA concen
tration in the synovium from the ACLT knees of the vehicle-treated ani
mals was greater than contralateral control, while this parameter was
not statistically different than contralateral control in the HA treat
ed animals. Conclusions: These results demonstrate a protective effect
of HA on preservation of the articulating surface of the femoral cond
yle following ACLT up to 21 weeks post-surgery.