Changes in sagittal ground reaction forces after intra-articular hyaluronate injections for knee osteoarthritis

Tang SF, Chen CP, Chen MJ, Pei Y-C, Lau Y-C, Leong C-P. Changes in sagittal ground reaction forces after intra-articular hyaluronate injections for knee osteoarthritis. Arch Phys Med Rehabil 2004;85:951-5. Objectives To examine the gait patterns and the sagittal ground reaction forces (GRFs) in persons with knee osteoarthritis (OA) after intra-articular injection of hyaluronate and to investigate the duration of its treatment effectiveness. Design Case-comparison study. Setting Gait laboratory in a tertiary care center. Participants Fifteen subjects (30 knees) with symptomatic knee OA (stage I or II, according to the Ahlbäck grading system), and 15 age-, mass-, and gender-matched non-OA control subjects (30 knees). Intervention After initial gait analysis, the group with knee OA received 5 weekly intra-articular injections of hyaluronate to bilateral knees. Gait analysis was performed again for the group with knee OA after the completion of hyaluronate injections. Main outcome measures Forceplate sagittal GRFs and gait parameters of velocity, cadence, step length, and stride time. Results The distinctive 2-peak force vector GRF was lost in persons with knee OA. The first peak rise time was significantly delayed (P<.05). The group with knee OA also revealed slower walking velocity and cadence, as well as longer stride time, than the control group (P<.05). The distinctive 2-peak force vector GRF diagram could be recovered in patients with knee OA after the completion of hyaluronate injections. Conclusions Gait patterns and GRFs improved significantly after intra-articular knee injection of hyaluronate in persons with Ahlbäck stages I and II knee OA. The clinical treatment effect was immediate and may last for 6 months or more.