title: Effect of variable-stiffness walking shoes on knee adduction moment, pain, and function in subjects with medial compartment knee osteoarthritis after 1 year.
abstract: This study investigated the load-modifying and clinical efficacy of variable-stiffness shoes after 12 months in subjects with medial compartment knee osteoarthritis. Subjects who completed a prior 6-month study were asked to wear their assigned constant-stiffness control or variable-stiffness intervention shoes during the remainder of the study. Changes in peak knee adduction moment, total Western Ontario and McMaster Universities (WOMAC), and WOMAC pain scores were assessed. Seventy-nine subjects were enrolled, and 55 completed the trial. Using an intention-to-treat analysis, the variable-stiffness shoes reduced the within-day peak knee adduction moment (-5.5%, p < 0.001) in the intervention subjects, while the constant-stiffness shoes increased the peak knee adduction moment in the control subjects (+3.1%, p = 0.015) at the 12-month visit. WOMAC pain and total scores for the intervention group were significantly reduced from baseline to 12 months (-32%, p = 0.002 and -35%, p = 0.007, respectively). The control group had a reduction of 27% in WOMAC pain score (p = 0.04) and no significant reduction in total WOMAC score. Reductions in WOMAC pain and total scores were similar between groups (p = 0.8 and p = 0.47, respectively). In the intervention group, reductions in adduction moment were related to improvements in pain and function (R(2)  = 0.11, p = 0.04). Analysis by disease severity revealed greater efficacy in adduction moment reduction in the less severe intervention group. While the long-term effects of the intervention shoes on pain and function did not differ from control, the data suggest wearing the intervention shoe reduces the within-day adduction moment after long-term wear, and thus should reduce loading on the affected medial compartment of the knee.
authors.affiliation: Bone and Joint Center, Palo Alto VA, Palo Alto, California, USA. jerhart@stanford.edu
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Erhart-Hledik
authors.forename: Barbara
authors.initials: B
authors.lastname: Elspas
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Giori
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Andriacchi
mesh_terms: D000368:Aged; D018771:Arthralgia / Q000503:physiopathology / Q000534:rehabilitation; D005260:Female; D005500:Follow-Up Studies; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009989:Orthotic Devices / Q000592:standards*; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000534:rehabilitation*; D012720:Severity of Illness Index; D012775:Shoes / Q000592:standards*; D016138:Walking / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology