Supplementary Data for Effects of Age and Knee Osteoarthritis on the Modular Control of Walking: A Pilot Study

Supplementary data for manuscript under review: Roelker SA, Koehn RR, Caruthers EJ, Schmitt LC, Chaudhari AMW, Siston RA. Effects of Age and Knee Osteoarthritis on the Modular Control of Walking: A Pilot Study.

Abstract: Older adults and individuals with knee osteoarthritis (KOA) often exhibit reduced locomotor function and altered muscle activity. Identifying age- and KOA-related changes to the modular control of gait may provide insight into the neurological mechanisms underlying reduced walking performance in these populations. The purpose of this pilot study was to determine if the modular control of walking differs between younger and older adults without KOA and adults with end-stage KOA. Kinematic, kinetic, and electromyography (EMG) data were collected from ten younger (23.9 ± 2.8 years) and ten older (62.4 ± 2.6 years) adults without KOA and ten KOA patients (63.5 ± 3.4 years) walking at their self-selected speed. Separate non-negative matrix factorizations determined the number of modules required to reconstruct each participant’s EMG. There was no significant difference (p = 0.056) in the number of required modules between younger adults (4.1 ± 1.0), older adults without KOA (3.4 ± 0.8), and KOA patients (3.1 ± 0.6). However, a significant association between module number and walking speed was observed (r = 0.401; p = 0.028) and the KOA patients walked significantly slower (1.01 ± 0.16 m/s) than the younger adults (1.24 ± 0.18 m/s; p = 0.026). In addition, KOA patients exhibited altered module activation timing profiles and composition (which muscles are associated with each module) characterized by increased muscle co-activity compared to unimpaired younger and older adults who required the same number of modules. Thus, disease-related changes in neuromuscular control strategy may be associated with functional deficits in KOA patients