BACKGROUND

Many adults undergo a contralateral total knee arthroplasty (TKA) within 5-10 years following the primary surgery. It is possible that asymmetric knee joint loading after unilateral TKA plays a role in contralateral knee osteoarthritis progression.

RESEARCH QUESTION

The purpose of this study was to determine differences in peak, cumulative and rate of loading within the compartments of the surgical and non-surgical knees during walking in adults 6 months post-TKA.

METHODS

30 participants underwent gait analysis with marker trajectory and analog data integrated into a musculoskeletal lower body model constructed in OpenSim. Normalized quadriceps/hamstring strength and radiographic alignment of the limbs was integrated into individual musculoskeletal models to improve optimization. Paired t-tests were used to compare differences in knee joint loading between limbs.

RESULTS

For primary outcomes, significantly greater total (p = 0.01, d=0.48), medial (p = 0.02, d=0.43) and lateral (p = 0.03, d=0.40) compartment peak knee loading was observed in the non-surgical knee compared to the surgical knee during early stance. Significantly greater peak total (p = 0.033, d=0.41) and medial (p = 0.045, d=0.38) compartment knee loading was observed in the non-surgical knee compared to the surgical knee during late stance. For secondary outcomes, greater peak vGRF (p = 0.01, d=0.66), cumulative loading (p = 0.03, d=0.41) and instantaneous loading rate (p = 0.00, d=1.44) were observed in the medial compartment on the non-surgical knee compared to the surgical knee during early stance. Greater peak vGRF (p = 0.01, d=0.66) was noted in the non-surgical limb compared to the surgical limb during late stance.

CONCLUSION

Peak knee loading, instantaneous loading rate, cumulative loading, and peak vGRF metrics were all greater on the non-surgical knee compared to the surgical knee post-TKA. These loading asymmetries were greatest for the medial and total joint compartments during early stance phase of the gait cycle leading to potential contralateral knee osteoarthritis progression.