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

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 Ahlb?ck 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 Ahlb?ck stages I and II knee OA. The clinical treatment effect was immediate and may last for 6 months or more.