Abstract: BACKGROUND: Gait dysfunction is one of the significant reasons for patient dissatisfaction following total knee arthroplasty. Clinical studies have identified a relationship between the preoperative strength of the quadriceps and hamstring muscles and postoperative gait dysfunction, but the exact nature of this correlation is not yet fully understood.
OBJECTIVE: To investigate the correlation between the preoperative strength of the quadriceps and hamstring muscles and postoperative gait dysfunction in total knee arthroplasty. 
METHODS: A retrospective analysis was conducted on longitudinal data from 70 patients who underwent unilateral primary total knee arthroplasty. Preoperative measurements included peak torque of the extensor and flexor muscles, peak torque/body weight, and total work. Six months postoperatively, the Timed Up and Go Test and gait speed were measured. Ridge regression analysis was used to identify factors influencing postoperative gait function. 
RESULTS AND CONCLUSION: (1) Preoperative peak torque, peak torque/body weight, and total work of the extensor muscles, as well as the peak torque and total work of the flexor muscles, showed a very strong positive correlation with postoperative gait speed (P < 0.001). The preoperative flexor muscle peak torque/body weight had a strong positive correlation with postoperative gait speed (P < 0.001). Preoperative extensor and flexor muscle peak torques, peak torque/body weight, and total work showed a very strong negative correlation with results from postoperative Timed Up and Go Test (P < 0.001). (2) Ridge regression analysis indicated a 94.2% likelihood that preoperative extensor muscle peak torque, peak torque/body weight, and total work, along with flexor muscle peak torque and total work, had a positive impact on gait speed after total knee arthroplasty (P < 0.001). The preoperative flexor muscle peak torque/body weight had a negative impact on postoperative gait speed (P < 0.001). There was an 87.7% likelihood that preoperative extensor and flexor muscle peak torques, peak torque/body weight, and total work, along with flexor muscle peak torque and total work, had a negative impact on postoperative Timed Up and Go Test (P < 0.05), while the flexor muscle peak torque/body weight had no impact on the Timed Up and Go Test (P > 0.05). (3) It is indicated that the strength of the quadriceps and hamstring muscles prior to total knee arthroplasty correlates with postoperative gait speed and Timed Up and Go Test, and can predict the outcomes of postoperative gait function. Enhancing preoperative knee muscle exercises may be a way to reduce the incidence of gait dysfunction following total knee arthroplasty.

Key words: total knee arthroplasty, peak torque, gait function, Timed Up and Go Test, gait speed