Changes in gait after bilateral meniscectomy in sheep: effect of two hyaluronan preparations

This study examined the effect of bilateral meniscectomy on ground reaction forces (GRFs) in sheep, and the therapeutic effect of two hyaluronan (HA) preparations. Eighteen sheep were subjected to bilateral lateral meniscectomy and were treated from 16 to 20 weeks postoperatively with intraarticular Hyalgan (Fidia Farmaceutici), HYADD4-G (a novel amide derivative; Fidia Farmaceutici), or saline placebo (n = 6 per group). GRFs were assessed at baseline and 6, 12, 16, 22, and 26 weeks postoperatively. Rheological parameters and HA content of synovial fluid samples were assessed using micro-Fourier rheometry. Meniscectomy significantly reduced GRF and abolished the normal two-peak vector. GRF deficits were partially ameliorated by both HA preparations: Hyalgan increased peak vertical forces at 6 weeks post-treatment (week 22), while HYADD4-G increased vertical impulse post-treatment. Both HA treatments, but not saline placebo, restored a twopeak composite force vector at 6 weeks post-treatment. Neither HA preparation significantly modulated osteoarthritis (OA) severity, or synovial fluid parameters. This study showed that GRF responses to bilateral meniscectomy in sheep mimic available data for human meniscectomy and OA patients. However, this time course suggests that gait deficits are temporally unrelated to observed cartilage or synovial fluid changes. The bilateral ovine meniscectomy model demonstrates modest but quantifiable changes in GRF that mimic human OA and are amenable to modification by known OA therapies such as HA.