Are Medial and Lateral Tibiofemoral Compressive Forces Different in Uphill Compared to Level Walking for Patients Following Total Knee Arthroplasty

The purpose of this study was to determine how tibiofemoral joint compressive forces and knee joint-spanning muscle forces during uphill walking change compared to level walking in patients with total knee arthroplasty (TKA). A musculoskeletal model capable of resolving total (TCF), medial (MCF), and lateral (LCF) tibiofemoral compressive forces was used to determine compressive forces and muscle forces during level and uphill walking on a 10° incline for twenty-five post TKA patients. A 2?2 (slope: level and 10° ? limb: replaced and non-replaced) repeated measures ANOVA was used to detect differences in knee contact forces between slope and limb conditions and their interaction. Peak loading-response TCF, MCF, and LCF were greater during uphill walking than level walking for non-replaced limbs. During uphill walking, peak loading-response TCF was smaller in the replaced limb compared to non-replaced limbs with no change in MCF or LCF. Peak knee extension moment and knee extensor muscle force were smaller in replaced limbs compared to non-replaced limbs during uphill walking. During level walking, replaced and non-replaced limbs experienced rather equal joint loading, however replaced limb experienced reduced joint loading during uphill walking. Differences in joint loading between replaced and non-replaced limbs were not present during level walking, suggesting compensation from the replaced limb during the more difficult task. Uphill walking following TKA promotes more balanced loading of replaced limbs during stance, however these benefits may come at the expense of increased loading on non-replaced limbs.