〔Abstract〕 ObjectiveTo investigate the relationship between lower limb alignment and knee functional gait after total knee arthroplasty (TKA) for varus knee deformity. MethodsA total of 94 patients with knee osteoarthritis and varus deformity underwent mechanically aligned TKA. The knee society score (KSS), hip-knee-ankle angle (HKA), medial proximal tibial angle (mMPTA), and gait parameters (step length, gait speed, cadence, thigh jerk acceleration, and thigh swing work) were assessed preoperatively and one month postoperatively. The correlation between KSS scores and changes in lower limb alignment was also analyzed. ResultsThe KSS clinical score of the operated knee significantly improved from 39.19 ± 9.55 preoperatively to 73.01 ± 6.90 postoperatively ( P<0.001). The KSS functional score increased from 41.12±10.66 to 56.33±7.41( P<0.001). Postoperative gait analysis revealed significant improvements in step length, gait speed, cadence, and thigh swing work ( P<0.001), while thigh jerk acceleration showed no significant change ( P=0.525). The HKA angle of the affected limb increased from 170.61±4.39 preoperatively to 177.30±3.49 postoperatively ( P<0.001). Similarly, the mMPTA angle increased from 83.95±3.32 to 89.15±1.94 ( P<0.001). Correlation analysis indicated that The KSS clinical score was positively correlated with HKA ( P<0.001) and mMPTA ( P<0.05) of the lower limb force line. The KSS functional score was positively correlated with HKA ( P<0.05) but not with mMPTA ( P>0.05). ConclusionIn patients with severe knee osteoarthritis due to varus deformity, TKA significantly alleviates pain and improves both clinical and functional KSS scores within one month postoperatively. Restoring lower limb mechanical alignment is positively associated with joint functional recovery and enhances gait performance.