Gait analysis and evaluation of knee buckling risk following total knee arthroplasty

[Purpose] Total knee arthroplasty (TKA) can alleviate pain and improve daily functioning in patients with knee osteoarthritis. However, postoperative decreases in knee extensor strength and limitations in joint range of motion (ROM) may increase the risk of knee buckling. This study aimed to investigate gait characteristics and mechanical conditions potentially associated with knee buckling in patients following TKA. [Participants and Methods] This study was conducted on patients following TKA. Based on the inclusion criteria, this study included 21 patients (25 knees; postoperative day 22.0 ± 10.5) with data for knee joint position sense, knee-extension strength, tibial acceleration, knee flexion angle, and electromyography (EMG) of vastus medialis, vastus lateralis (VL), rectus femoris, tibialis anterior, and lateral head of the gastrocnemius during gait. EMG signals were normalized using the maximal voluntary contraction method. Participants walked six steps at a self-selected speed and the second gait cycle on the operated side was analyzed. [Results] Knee joint position sense and knee flexion angle at initial contact (IC) showed a moderate positive correlation. Moderate negative correlations were observed between postoperative days and VL activity and between maximum vertical direction tibial acceleration and VL activity. [Conclusion] Decreased position sense may affect knee joint control at IC, potentially manifesting as an increased knee flexion angle and suggesting the involvement of mechanical conditions associated with knee buckling. Furthermore, VL muscle activity during gait decreased with increasing postoperative days, and greater VL muscle activity was associated with gait patterns characterized by reduced vertical tibial acceleration.