Effects of hyaluronan on the healing of rabbit meniscus injured in the peripheral region.

The effect of hyaluronan (hyaluronic acid; HA) on the healing of rabbit meniscus injured in the peripheral region was assessed. A longitudinal tear was created in the peripheral region of the medial meniscus in 20 mature New Zealand white rabbits. One week after surgery, HA was injected into the left knee joint once a week for 5 weeks (HA group), while saline was injected into the right knee (control group). Six and 12 weeks after surgery, gross morphology, histology, and biochemical evaluations were performed. On gross morphological examination, there was evidence of meniscal healing in both groups, but the healing rate of the HA group was significantly higher than that of the control group at 12 weeks. Histologically, meniscal healing started at the tibial portion of the meniscal injury at 6 weeks in both groups, then advanced in the direction of the femoral surface at 12 weeks in the HA group. Biochemically, water and glycosaminoglycan contents did not differ significantly between the two groups. Hyaluronan maintained the healing process of the injured menisci, especially in the femoral surface, up to 12 weeks after injury.