Dynamic Margin of Stability During Walking Differs Between End-Stage Hip, Knee, and Ankle Arthritis

End-stage arthritis of the hip, knee, or ankle leads to differential gait adaptations, but the differences in gait stability remain poorly understood. This study examined whether dynamic gait stability differed between patients with end-stage hip arthritis (HA), knee arthritis (KA) and ankle arthritis (AA), and matched healthy controls (HC). Anteroposterior (AP) and mediolateral (ML) Margin of Stability (MoS) were determined at heel strike, contralateral toe-off, and midstance during overground walking in 30 HA, 20 KA, 30 AA, and 30 HC participants. Data was analyzed using linear mixed-effects models with gait speed included as a fixed effect and participant as a random effect. A significant interaction was found between group (HA, KA, AA, HC) and limb (arthritic, non-arthritic) for every MoS variable (p < 0.001). HA and AA exhibited greater arthritic limb ML MoS during single support (p < 0.001) and smaller non-arthritic limb AP MoS at heel-strike (p < 0.033) when compared to HC. HA exhibited the least conservative non-arthritic limb AP MoS at midstance (p = 0.044), suggesting reduced AP stability. KA showed the smallest non-arthritic limb ML MoS at heel-strike (p < 0.022), indicating greater lateral instability. Within all patient groups (HA, KA, AA), ML stability was more conservative in the arthritic limb compared to the non-arthritic limb (p < 0.001). These findings suggest isolated lower extremity joint arthritis differentially impacts gait stability depending on the affected joint and limb, highlighting the need for targeted rehabilitation strategies to address stability deficits based on the joint impacted by arthritis.